adjust_jmp_off() incorrectly used the insn->imm field for all overflow check,
which is incorrect as that should only be done or the BPF_JMP32 | BPF_JA case,
not the general jump instruction case. Fix it by using insn->off for overflow
check in the general case.
Fixes: 5337ac4c9b ("bpf: Fix the corner case with may_goto and jump to the 1st insn.")
Signed-off-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240712080127.136608-2-shung-hsi.yu@suse.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, BPF kfuncs which accept trusted pointer arguments
i.e. those flagged as KF_TRUSTED_ARGS, KF_RCU, or KF_RELEASE, all
require an original/unmodified trusted pointer argument to be supplied
to them. By original/unmodified, it means that the backing register
holding the trusted pointer argument that is to be supplied to the BPF
kfunc must have its fixed offset set to zero, or else the BPF verifier
will outright reject the BPF program load. However, this zero fixed
offset constraint that is currently enforced by the BPF verifier onto
BPF kfuncs specifically flagged to accept KF_TRUSTED_ARGS or KF_RCU
trusted pointer arguments is rather unnecessary, and can limit their
usability in practice. Specifically, it completely eliminates the
possibility of constructing a derived trusted pointer from an original
trusted pointer. To put it simply, a derived pointer is a pointer
which points to one of the nested member fields of the object being
pointed to by the original trusted pointer.
This patch relaxes the zero fixed offset constraint that is enforced
upon BPF kfuncs which specifically accept KF_TRUSTED_ARGS, or KF_RCU
arguments. Although, the zero fixed offset constraint technically also
applies to BPF kfuncs accepting KF_RELEASE arguments, relaxing this
constraint for such BPF kfuncs has subtle and unwanted
side-effects. This was discovered by experimenting a little further
with an initial version of this patch series [0]. The primary issue
with relaxing the zero fixed offset constraint on BPF kfuncs accepting
KF_RELEASE arguments is that it'd would open up the opportunity for
BPF programs to supply both trusted pointers and derived trusted
pointers to them. For KF_RELEASE BPF kfuncs specifically, this could
be problematic as resources associated with the backing pointer could
be released by the backing BPF kfunc and cause instabilities for the
rest of the kernel.
With this new fixed offset semantic in-place for BPF kfuncs accepting
KF_TRUSTED_ARGS and KF_RCU arguments, we now have more flexibility
when it comes to the BPF kfuncs that we're able to introduce moving
forward.
Early discussions covering the possibility of relaxing the zero fixed
offset constraint can be found using the link below. This will provide
more context on where all this has stemmed from [1].
Notably, pre-existing tests have been updated such that they provide
coverage for the updated zero fixed offset
functionality. Specifically, the nested offset test was converted from
a negative to positive test as it was already designed to assert zero
fixed offset semantics of a KF_TRUSTED_ARGS BPF kfunc.
[0] https://lore.kernel.org/bpf/ZnA9ndnXKtHOuYMe@google.com/
[1] https://lore.kernel.org/bpf/ZhkbrM55MKQ0KeIV@google.com/
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20240709210939.1544011-1-mattbobrowski@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2024-07-08
The following pull-request contains BPF updates for your *net-next* tree.
We've added 102 non-merge commits during the last 28 day(s) which contain
a total of 127 files changed, 4606 insertions(+), 980 deletions(-).
The main changes are:
1) Support resilient split BTF which cuts down on duplication and makes BTF
as compact as possible wrt BTF from modules, from Alan Maguire & Eduard Zingerman.
2) Add support for dumping kfunc prototypes from BTF which enables both detecting
as well as dumping compilable prototypes for kfuncs, from Daniel Xu.
3) Batch of s390x BPF JIT improvements to add support for BPF arena and to implement
support for BPF exceptions, from Ilya Leoshkevich.
4) Batch of riscv64 BPF JIT improvements in particular to add 12-argument support
for BPF trampolines and to utilize bpf_prog_pack for the latter, from Pu Lehui.
5) Extend BPF test infrastructure to add a CHECKSUM_COMPLETE validation option
for skbs and add coverage along with it, from Vadim Fedorenko.
6) Inline bpf_get_current_task/_btf() helpers in the arm64 BPF JIT which gives
a small 1% performance improvement in micro-benchmarks, from Puranjay Mohan.
7) Extend the BPF verifier to track the delta between linked registers in order
to better deal with recent LLVM code optimizations, from Alexei Starovoitov.
8) Fix bpf_wq_set_callback_impl() kfunc signature where the third argument should
have been a pointer to the map value, from Benjamin Tissoires.
9) Extend BPF selftests to add regular expression support for test output matching
and adjust some of the selftest when compiled under gcc, from Cupertino Miranda.
10) Simplify task_file_seq_get_next() and remove an unnecessary loop which always
iterates exactly once anyway, from Dan Carpenter.
11) Add the capability to offload the netfilter flowtable in XDP layer through
kfuncs, from Florian Westphal & Lorenzo Bianconi.
12) Various cleanups in networking helpers in BPF selftests to shave off a few
lines of open-coded functions on client/server handling, from Geliang Tang.
13) Properly propagate prog->aux->tail_call_reachable out of BPF verifier, so
that x86 JIT does not need to implement detection, from Leon Hwang.
14) Fix BPF verifier to add a missing check_func_arg_reg_off() to prevent an
out-of-bounds memory access for dynpointers, from Matt Bobrowski.
15) Fix bpf_session_cookie() kfunc to return __u64 instead of long pointer as
it might lead to problems on 32-bit archs, from Jiri Olsa.
16) Enhance traffic validation and dynamic batch size support in xsk selftests,
from Tushar Vyavahare.
bpf-next-for-netdev
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (102 commits)
selftests/bpf: DENYLIST.aarch64: Remove fexit_sleep
selftests/bpf: amend for wrong bpf_wq_set_callback_impl signature
bpf: helpers: fix bpf_wq_set_callback_impl signature
libbpf: Add NULL checks to bpf_object__{prev_map,next_map}
selftests/bpf: Remove exceptions tests from DENYLIST.s390x
s390/bpf: Implement exceptions
s390/bpf: Change seen_reg to a mask
bpf: Remove unnecessary loop in task_file_seq_get_next()
riscv, bpf: Optimize stack usage of trampoline
bpf, devmap: Add .map_alloc_check
selftests/bpf: Remove arena tests from DENYLIST.s390x
selftests/bpf: Add UAF tests for arena atomics
selftests/bpf: Introduce __arena_global
s390/bpf: Support arena atomics
s390/bpf: Enable arena
s390/bpf: Support address space cast instruction
s390/bpf: Support BPF_PROBE_MEM32
s390/bpf: Land on the next JITed instruction after exception
s390/bpf: Introduce pre- and post- probe functions
s390/bpf: Get rid of get_probe_mem_regno()
...
====================
Link: https://patch.msgid.link/20240708221438.10974-1-daniel@iogearbox.net
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Zero-extending results of atomic probe operations fails with:
verifier bug. zext_dst is set, but no reg is defined
The problem is that insn_def_regno() handles BPF_ATOMICs, but not
BPF_PROBE_ATOMICs. Fix by adding the missing condition.
Fixes: d503a04f8b ("bpf: Add support for certain atomics in bpf_arena to x86 JIT")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240701234304.14336-2-iii@linux.ibm.com
Cross-merge networking fixes after downstream PR.
No conflicts.
Adjacent changes:
e3f02f32a0 ("ionic: fix kernel panic due to multi-buffer handling")
d9c0420999 ("ionic: Mark error paths in the data path as unlikely")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Currently, it's possible to pass in a modified CONST_PTR_TO_DYNPTR to
a global function as an argument. The adverse effects of this is that
BPF helpers can continue to make use of this modified
CONST_PTR_TO_DYNPTR from within the context of the global function,
which can unintentionally result in out-of-bounds memory accesses and
therefore compromise overall system stability i.e.
[ 244.157771] BUG: KASAN: slab-out-of-bounds in bpf_dynptr_data+0x137/0x140
[ 244.161345] Read of size 8 at addr ffff88810914be68 by task test_progs/302
[ 244.167151] CPU: 0 PID: 302 Comm: test_progs Tainted: G O E 6.10.0-rc3-00131-g66b586715063 #533
[ 244.174318] Call Trace:
[ 244.175787] <TASK>
[ 244.177356] dump_stack_lvl+0x66/0xa0
[ 244.179531] print_report+0xce/0x670
[ 244.182314] ? __virt_addr_valid+0x200/0x3e0
[ 244.184908] kasan_report+0xd7/0x110
[ 244.187408] ? bpf_dynptr_data+0x137/0x140
[ 244.189714] ? bpf_dynptr_data+0x137/0x140
[ 244.192020] bpf_dynptr_data+0x137/0x140
[ 244.194264] bpf_prog_b02a02fdd2bdc5fa_global_call_bpf_dynptr_data+0x22/0x26
[ 244.198044] bpf_prog_b0fe7b9d7dc3abde_callback_adjust_bpf_dynptr_reg_off+0x1f/0x23
[ 244.202136] bpf_user_ringbuf_drain+0x2c7/0x570
[ 244.204744] ? 0xffffffffc0009e58
[ 244.206593] ? __pfx_bpf_user_ringbuf_drain+0x10/0x10
[ 244.209795] bpf_prog_33ab33f6a804ba2d_user_ringbuf_callback_const_ptr_to_dynptr_reg_off+0x47/0x4b
[ 244.215922] bpf_trampoline_6442502480+0x43/0xe3
[ 244.218691] __x64_sys_prlimit64+0x9/0xf0
[ 244.220912] do_syscall_64+0xc1/0x1d0
[ 244.223043] entry_SYSCALL_64_after_hwframe+0x77/0x7f
[ 244.226458] RIP: 0033:0x7ffa3eb8f059
[ 244.228582] Code: 08 89 e8 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 8f 1d 0d 00 f7 d8 64 89 01 48
[ 244.241307] RSP: 002b:00007ffa3e9c6eb8 EFLAGS: 00000206 ORIG_RAX: 000000000000012e
[ 244.246474] RAX: ffffffffffffffda RBX: 00007ffa3e9c7cdc RCX: 00007ffa3eb8f059
[ 244.250478] RDX: 00007ffa3eb162b4 RSI: 0000000000000000 RDI: 00007ffa3e9c7fb0
[ 244.255396] RBP: 00007ffa3e9c6ed0 R08: 00007ffa3e9c76c0 R09: 0000000000000000
[ 244.260195] R10: 0000000000000000 R11: 0000000000000206 R12: ffffffffffffff80
[ 244.264201] R13: 000000000000001c R14: 00007ffc5d6b4260 R15: 00007ffa3e1c7000
[ 244.268303] </TASK>
Add a check_func_arg_reg_off() to the path in which the BPF verifier
verifies the arguments of global function arguments, specifically
those which take an argument of type ARG_PTR_TO_DYNPTR |
MEM_RDONLY. Also, process_dynptr_func() doesn't appear to perform any
explicit and strict type matching on the supplied register type, so
let's also enforce that a register either type PTR_TO_STACK or
CONST_PTR_TO_DYNPTR is by the caller.
Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Matt Bobrowski <mattbobrowski@google.com>
Link: https://lore.kernel.org/r/20240625062857.92760-1-mattbobrowski@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Zac's syzbot crafted a bpf prog that exposed two bugs in may_goto.
The 1st bug is the way may_goto is patched. When offset is negative
it should be patched differently.
The 2nd bug is in the verifier:
when current state may_goto_depth is equal to visited state may_goto_depth
it means there is an actual infinite loop. It's not correct to prune
exploration of the program at this point.
Note, that this check doesn't limit the program to only one may_goto insn,
since 2nd and any further may_goto will increment may_goto_depth only
in the queued state pushed for future exploration. The current state
will have may_goto_depth == 0 regardless of number of may_goto insns
and the verifier has to explore the program until bpf_exit.
Fixes: 011832b97b ("bpf: Introduce may_goto instruction")
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Closes: https://lore.kernel.org/bpf/CAADnVQL-15aNp04-cyHRn47Yv61NXfYyhopyZtUyxNojUZUXpA@mail.gmail.com/
Link: https://lore.kernel.org/bpf/20240619235355.85031-1-alexei.starovoitov@gmail.com
When the following program is processed by the verifier:
L1: may_goto L2
goto L1
L2: w0 = 0
exit
the may_goto insn is first converted to:
L1: r11 = *(u64 *)(r10 -8)
if r11 == 0x0 goto L2
r11 -= 1
*(u64 *)(r10 -8) = r11
goto L1
L2: w0 = 0
exit
then later as the last step the verifier inserts:
*(u64 *)(r10 -8) = BPF_MAX_LOOPS
as the first insn of the program to initialize loop count.
When the first insn happens to be a branch target of some jmp the
bpf_patch_insn_data() logic will produce:
L1: *(u64 *)(r10 -8) = BPF_MAX_LOOPS
r11 = *(u64 *)(r10 -8)
if r11 == 0x0 goto L2
r11 -= 1
*(u64 *)(r10 -8) = r11
goto L1
L2: w0 = 0
exit
because instruction patching adjusts all jmps and calls, but for this
particular corner case it's incorrect and the L1 label should be one
instruction down, like:
*(u64 *)(r10 -8) = BPF_MAX_LOOPS
L1: r11 = *(u64 *)(r10 -8)
if r11 == 0x0 goto L2
r11 -= 1
*(u64 *)(r10 -8) = r11
goto L1
L2: w0 = 0
exit
and that's what this patch is fixing.
After bpf_patch_insn_data() call adjust_jmp_off() to adjust all jmps
that point to newly insert BPF_ST insn to point to insn after.
Note that bpf_patch_insn_data() cannot easily be changed to accommodate
this logic, since jumps that point before or after a sequence of patched
instructions have to be adjusted with the full length of the patch.
Conceptually it's somewhat similar to "insert" of instructions between other
instructions with weird semantics. Like "insert" before 1st insn would require
adjustment of CALL insns to point to newly inserted 1st insn, but not an
adjustment JMP insns that point to 1st, yet still adjusting JMP insns that
cross over 1st insn (point to insn before or insn after), hence use simple
adjust_jmp_off() logic to fix this corner case. Ideally bpf_patch_insn_data()
would have an auxiliary info to say where 'the start of newly inserted patch
is', but it would be too complex for backport.
Fixes: 011832b97b ("bpf: Introduce may_goto instruction")
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Closes: https://lore.kernel.org/bpf/CAADnVQJ_WWx8w4b=6Gc2EpzAjgv+6A0ridnMz2TvS2egj4r3Gw@mail.gmail.com/
Link: https://lore.kernel.org/bpf/20240619011859.79334-1-alexei.starovoitov@gmail.com
Fixes a compiler warning. The __bpf_free_used_btfs function
was taking an extra unused struct bpf_prog_aux *aux param
Signed-off-by: Rafael Passos <rafael@rcpassos.me>
Link: https://lore.kernel.org/r/20240615022641.210320-3-rafael@rcpassos.me
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It's confusing to inspect 'prog->aux->tail_call_reachable' with drgn[0],
when bpf prog has tail call but 'tail_call_reachable' is false.
This patch corrects 'tail_call_reachable' when bpf prog has tail call.
Signed-off-by: Leon Hwang <hffilwlqm@gmail.com>
Link: https://lore.kernel.org/r/20240610124224.34673-2-hffilwlqm@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cross-merge networking fixes after downstream PR.
Conflicts:
drivers/net/ethernet/broadcom/bnxt/bnxt.c
1e7962114c ("bnxt_en: Restore PTP tx_avail count in case of skb_pad() error")
165f87691a ("bnxt_en: add timestamping statistics support")
No adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In coerce_subreg_to_size_sx(), for the case where upper
sign extension bits are the same for smax32 and smin32
values, we missed to setup properly. This is especially
problematic if both smax32 and smin32's sign extension
bits are 1.
The following is a simple example illustrating the inconsistent
verifier states due to missed var_off:
0: (85) call bpf_get_prandom_u32#7 ; R0_w=scalar()
1: (bf) r3 = r0 ; R0_w=scalar(id=1) R3_w=scalar(id=1)
2: (57) r3 &= 15 ; R3_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=15,var_off=(0x0; 0xf))
3: (47) r3 |= 128 ; R3_w=scalar(smin=umin=smin32=umin32=128,smax=umax=smax32=umax32=143,var_off=(0x80; 0xf))
4: (bc) w7 = (s8)w3
REG INVARIANTS VIOLATION (alu): range bounds violation u64=[0xffffff80, 0x8f] s64=[0xffffff80, 0x8f]
u32=[0xffffff80, 0x8f] s32=[0x80, 0xffffff8f] var_off=(0x80, 0xf)
The var_off=(0x80, 0xf) is not correct, and the correct one should
be var_off=(0xffffff80; 0xf) since from insn 3, we know that at
insn 4, the sign extension bits will be 1. This patch fixed this
issue by setting var_off properly.
Fixes: 8100928c88 ("bpf: Support new sign-extension mov insns")
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240615174632.3995278-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Zac reported a verification failure and Alexei reproduced the issue
with a simple reproducer ([1]). The verification failure is due to missed
setting for var_off.
The following is the reproducer in [1]:
0: R1=ctx() R10=fp0
0: (71) r3 = *(u8 *)(r10 -387) ;
R3_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) R10=fp0
1: (bc) w7 = (s8)w3 ;
R3_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff))
R7_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=127,var_off=(0x0; 0x7f))
2: (36) if w7 >= 0x2533823b goto pc-3
mark_precise: frame0: last_idx 2 first_idx 0 subseq_idx -1
mark_precise: frame0: regs=r7 stack= before 1: (bc) w7 = (s8)w3
mark_precise: frame0: regs=r3 stack= before 0: (71) r3 = *(u8 *)(r10 -387)
2: R7_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=127,var_off=(0x0; 0x7f))
3: (b4) w0 = 0 ; R0_w=0
4: (95) exit
Note that after insn 1, the var_off for R7 is (0x0; 0x7f). This is not correct
since upper 24 bits of w7 could be 0 or 1. So correct var_off should be
(0x0; 0xffffffff). Missing var_off setting in set_sext32_default_val() caused later
incorrect analysis in zext_32_to_64(dst_reg) and reg_bounds_sync(dst_reg).
To fix the issue, set var_off correctly in set_sext32_default_val(). The correct
reg state after insn 1 becomes:
1: (bc) w7 = (s8)w3 ;
R3_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff))
R7_w=scalar(smin=0,smax=umax=0xffffffff,smin32=-128,smax32=127,var_off=(0x0; 0xffffffff))
and at insn 2, the verifier correctly determines either branch is possible.
[1] https://lore.kernel.org/bpf/CAADnVQLPU0Shz7dWV4bn2BgtGdxN3uFHPeobGBA72tpg5Xoykw@mail.gmail.com/
Fixes: 8100928c88 ("bpf: Support new sign-extension mov insns")
Reported-by: Zac Ecob <zacecob@protonmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240615174626.3994813-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Compilers can generate the code
r1 = r2
r1 += 0x1
if r2 < 1000 goto ...
use knowledge of r2 range in subsequent r1 operations
So remember constant delta between r2 and r1 and update r1 after 'if' condition.
Unfortunately LLVM still uses this pattern for loops with 'can_loop' construct:
for (i = 0; i < 1000 && can_loop; i++)
The "undo" pass was introduced in LLVM
https://reviews.llvm.org/D121937
to prevent this optimization, but it cannot cover all cases.
Instead of fighting middle end optimizer in BPF backend teach the verifier
about this pattern.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240613013815.953-3-alexei.starovoitov@gmail.com
Some arguments to kfuncs might be NULL in some cases. But currently it's
not possible to pass NULL to any BTF structures because the check for
the suffix is located after all type checks. Move it to earlier place
to allow nullable args.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
Link: https://lore.kernel.org/r/20240613211817.1551967-2-vadfed@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
pcpu_hot (defined in arch/x86) is not available on user mode linux (ARCH=um)
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Fixes: 1ae6921009 ("bpf: inline bpf_get_smp_processor_id() helper")
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Link: https://lore.kernel.org/r/20240613173146.2524647-1-maze@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The fake_reg moved into env->fake_reg given it consumes a lot of stack
space (120 bytes). Migrate the fake_reg in check_stack_write_fixed_off()
as well now that we have it.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240613115310.25383-2-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Juan reported that after doing some changes to buzzer [0] and implementing
a new fuzzing strategy guided by coverage, they noticed the following in
one of the probes:
[...]
13: (79) r6 = *(u64 *)(r0 +0) ; R0=map_value(ks=4,vs=8) R6_w=scalar()
14: (b7) r0 = 0 ; R0_w=0
15: (b4) w0 = -1 ; R0_w=0xffffffff
16: (74) w0 >>= 1 ; R0_w=0x7fffffff
17: (5c) w6 &= w0 ; R0_w=0x7fffffff R6_w=scalar(smin=smin32=0,smax=umax=umax32=0x7fffffff,var_off=(0x0; 0x7fffffff))
18: (44) w6 |= 2 ; R6_w=scalar(smin=umin=smin32=umin32=2,smax=umax=umax32=0x7fffffff,var_off=(0x2; 0x7ffffffd))
19: (56) if w6 != 0x7ffffffd goto pc+1
REG INVARIANTS VIOLATION (true_reg2): range bounds violation u64=[0x7fffffff, 0x7ffffffd] s64=[0x7fffffff, 0x7ffffffd] u32=[0x7fffffff, 0x7ffffffd] s32=[0x7fffffff, 0x7ffffffd] var_off=(0x7fffffff, 0x0)
REG INVARIANTS VIOLATION (false_reg1): range bounds violation u64=[0x7fffffff, 0x7ffffffd] s64=[0x7fffffff, 0x7ffffffd] u32=[0x7fffffff, 0x7ffffffd] s32=[0x7fffffff, 0x7ffffffd] var_off=(0x7fffffff, 0x0)
REG INVARIANTS VIOLATION (false_reg2): const tnum out of sync with range bounds u64=[0x0, 0xffffffffffffffff] s64=[0x8000000000000000, 0x7fffffffffffffff] u32=[0x0, 0xffffffff] s32=[0x80000000, 0x7fffffff] var_off=(0x7fffffff, 0x0)
19: R6_w=0x7fffffff
20: (95) exit
from 19 to 21: R0=0x7fffffff R6=scalar(smin=umin=smin32=umin32=2,smax=umax=smax32=umax32=0x7ffffffe,var_off=(0x2; 0x7ffffffd)) R7=map_ptr(ks=4,vs=8) R9=ctx() R10=fp0 fp-24=map_ptr(ks=4,vs=8) fp-40=mmmmmmmm
21: R0=0x7fffffff R6=scalar(smin=umin=smin32=umin32=2,smax=umax=smax32=umax32=0x7ffffffe,var_off=(0x2; 0x7ffffffd)) R7=map_ptr(ks=4,vs=8) R9=ctx() R10=fp0 fp-24=map_ptr(ks=4,vs=8) fp-40=mmmmmmmm
21: (14) w6 -= 2147483632 ; R6_w=scalar(smin=umin=umin32=2,smax=umax=0xffffffff,smin32=0x80000012,smax32=14,var_off=(0x2; 0xfffffffd))
22: (76) if w6 s>= 0xe goto pc+1 ; R6_w=scalar(smin=umin=umin32=2,smax=umax=0xffffffff,smin32=0x80000012,smax32=13,var_off=(0x2; 0xfffffffd))
23: (95) exit
from 22 to 24: R0=0x7fffffff R6_w=14 R7=map_ptr(ks=4,vs=8) R9=ctx() R10=fp0 fp-24=map_ptr(ks=4,vs=8) fp-40=mmmmmmmm
24: R0=0x7fffffff R6_w=14 R7=map_ptr(ks=4,vs=8) R9=ctx() R10=fp0 fp-24=map_ptr(ks=4,vs=8) fp-40=mmmmmmmm
24: (14) w6 -= 14 ; R6_w=0
[...]
What can be seen here is a register invariant violation on line 19. After
the binary-or in line 18, the verifier knows that bit 2 is set but knows
nothing about the rest of the content which was loaded from a map value,
meaning, range is [2,0x7fffffff] with var_off=(0x2; 0x7ffffffd). When in
line 19 the verifier analyzes the branch, it splits the register states
in reg_set_min_max() into the registers of the true branch (true_reg1,
true_reg2) and the registers of the false branch (false_reg1, false_reg2).
Since the test is w6 != 0x7ffffffd, the src_reg is a known constant.
Internally, the verifier creates a "fake" register initialized as scalar
to the value of 0x7ffffffd, and then passes it onto reg_set_min_max(). Now,
for line 19, it is mathematically impossible to take the false branch of
this program, yet the verifier analyzes it. It is impossible because the
second bit of r6 will be set due to the prior or operation and the
constant in the condition has that bit unset (hex(fd) == binary(1111 1101).
When the verifier first analyzes the false / fall-through branch, it will
compute an intersection between the var_off of r6 and of the constant. This
is because the verifier creates a "fake" register initialized to the value
of the constant. The intersection result later refines both registers in
regs_refine_cond_op():
[...]
t = tnum_intersect(tnum_subreg(reg1->var_off), tnum_subreg(reg2->var_off));
reg1->var_off = tnum_with_subreg(reg1->var_off, t);
reg2->var_off = tnum_with_subreg(reg2->var_off, t);
[...]
Since the verifier is analyzing the false branch of the conditional jump,
reg1 is equal to false_reg1 and reg2 is equal to false_reg2, i.e. the reg2
is the "fake" register that was meant to hold a constant value. The resulting
var_off of the intersection says that both registers now hold a known value
of var_off=(0x7fffffff, 0x0) or in other words: this operation manages to
make the verifier think that the "constant" value that was passed in the
jump operation now holds a different value.
Normally this would not be an issue since it should not influence the true
branch, however, false_reg2 and true_reg2 are pointers to the same "fake"
register. Meaning, the false branch can influence the results of the true
branch. In line 24, the verifier assumes R6_w=0, but the actual runtime
value in this case is 1. The fix is simply not passing in the same "fake"
register location as inputs to reg_set_min_max(), but instead making a
copy. Moving the fake_reg into the env also reduces stack consumption by
120 bytes. With this, the verifier successfully rejects invalid accesses
from the test program.
[0] https://github.com/google/buzzer
Fixes: 67420501e8 ("bpf: generalize reg_set_min_max() to handle non-const register comparisons")
Reported-by: Juan José López Jaimez <jjlopezjaimez@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/20240613115310.25383-1-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Previously, kfunc declarations in bpf_kfuncs.h (and others) used "user
facing" types for kfuncs prototypes while the actual kfunc definitions
used "kernel facing" types. More specifically: bpf_dynptr vs
bpf_dynptr_kern, __sk_buff vs sk_buff, and xdp_md vs xdp_buff.
It wasn't an issue before, as the verifier allows aliased types.
However, since we are now generating kfunc prototypes in vmlinux.h (in
addition to keeping bpf_kfuncs.h around), this conflict creates
compilation errors.
Fix this conflict by using "user facing" types in kfunc definitions.
This results in more casts, but otherwise has no additional runtime
cost.
Note, similar to 5b268d1ebc ("bpf: Have bpf_rdonly_cast() take a const
pointer"), we also make kfuncs take const arguments where appropriate in
order to make the kfunc more permissive.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/b58346a63a0e66bc9b7504da751b526b0b189a67.1718207789.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, if a kfunc accepts a projection type as an argument (eg
struct __sk_buff *), the caller must exactly provide exactly the same
type with provable provenance.
However in practice, kfuncs that accept projection types _must_ cast to
the underlying type before use b/c projection type layouts are
completely made up. Thus, it is ok to relax the verifier rules around
implicit conversions.
We will use this functionality in the next commit when we align kfuncs
to user-facing types.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/e2c025cb09ccfd4af1ec9e18284dc3cecff7514d.1718207789.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2024-06-06
We've added 54 non-merge commits during the last 10 day(s) which contain
a total of 50 files changed, 1887 insertions(+), 527 deletions(-).
The main changes are:
1) Add a user space notification mechanism via epoll when a struct_ops
object is getting detached/unregistered, from Kui-Feng Lee.
2) Big batch of BPF selftest refactoring for sockmap and BPF congctl
tests, from Geliang Tang.
3) Add BTF field (type and string fields, right now) iterator support
to libbpf instead of using existing callback-based approaches,
from Andrii Nakryiko.
4) Extend BPF selftests for the latter with a new btf_field_iter
selftest, from Alan Maguire.
5) Add new kfuncs for a generic, open-coded bits iterator,
from Yafang Shao.
6) Fix BPF selftests' kallsyms_find() helper under kernels configured
with CONFIG_LTO_CLANG_THIN, from Yonghong Song.
7) Remove a bunch of unused structs in BPF selftests,
from David Alan Gilbert.
8) Convert test_sockmap section names into names understood by libbpf
so it can deduce program type and attach type, from Jakub Sitnicki.
9) Extend libbpf with the ability to configure log verbosity
via LIBBPF_LOG_LEVEL environment variable, from Mykyta Yatsenko.
10) Fix BPF selftests with regards to bpf_cookie and find_vma flakiness
in nested VMs, from Song Liu.
11) Extend riscv32/64 JITs to introduce shift/add helpers to generate Zba
optimization, from Xiao Wang.
12) Enable BPF programs to declare arrays and struct fields with kptr,
bpf_rb_root, and bpf_list_head, from Kui-Feng Lee.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (54 commits)
selftests/bpf: Drop useless arguments of do_test in bpf_tcp_ca
selftests/bpf: Use start_test in test_dctcp in bpf_tcp_ca
selftests/bpf: Use start_test in test_dctcp_fallback in bpf_tcp_ca
selftests/bpf: Add start_test helper in bpf_tcp_ca
selftests/bpf: Use connect_to_fd_opts in do_test in bpf_tcp_ca
libbpf: Auto-attach struct_ops BPF maps in BPF skeleton
selftests/bpf: Add btf_field_iter selftests
selftests/bpf: Fix send_signal test with nested CONFIG_PARAVIRT
libbpf: Remove callback-based type/string BTF field visitor helpers
bpftool: Use BTF field iterator in btfgen
libbpf: Make use of BTF field iterator in BTF handling code
libbpf: Make use of BTF field iterator in BPF linker code
libbpf: Add BTF field iterator
selftests/bpf: Ignore .llvm.<hash> suffix in kallsyms_find()
selftests/bpf: Fix bpf_cookie and find_vma in nested VM
selftests/bpf: Test global bpf_list_head arrays.
selftests/bpf: Test global bpf_rb_root arrays and fields in nested struct types.
selftests/bpf: Test kptr arrays and kptrs in nested struct fields.
bpf: limit the number of levels of a nested struct type.
bpf: look into the types of the fields of a struct type recursively.
...
====================
Link: https://lore.kernel.org/r/20240606223146.23020-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
field->size has been initialized by bpf_parse_fields() with the value
returned by btf_field_type_size(). Use it instead of calling
btf_field_type_size() again.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240523174202.461236-3-thinker.li@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
reg_find_field_offset() always return a btf_field with a matching offset
value. Checking the offset of the returned btf_field is unnecessary.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240523174202.461236-2-thinker.li@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The bpf_session_cookie is unavailable for !CONFIG_FPROBE as reported
by Sebastian [1].
To fix that we remove CONFIG_FPROBE ifdef for session kfuncs, which
is fine, because there's filter for session programs.
Then based on bpf_trace.o dependency:
obj-$(CONFIG_BPF_EVENTS) += bpf_trace.o
we add bpf_session_cookie BTF_ID in special_kfunc_set list dependency
on CONFIG_BPF_EVENTS.
[1] https://lore.kernel.org/bpf/20240531071557.MvfIqkn7@linutronix.de/T/#m71c6d5ec71db2967288cb79acedc15cc5dbfeec5
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Fixes: 5c919acef8 ("bpf: Add support for kprobe session cookie")
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20240531194500.2967187-1-jolsa@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We have seen an influx of syzkaller reports where a BPF program attached to
a tracepoint triggers a locking rule violation by performing a map_delete
on a sockmap/sockhash.
We don't intend to support this artificial use scenario. Extend the
existing verifier allowed-program-type check for updating sockmap/sockhash
to also cover deleting from a map.
From now on only BPF programs which were previously allowed to update
sockmap/sockhash can delete from these map types.
Fixes: ff91059932 ("bpf, sockmap: Prevent lock inversion deadlock in map delete elem")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: syzbot+ec941d6e24f633a59172@syzkaller.appspotmail.com
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+ec941d6e24f633a59172@syzkaller.appspotmail.com
Acked-by: John Fastabend <john.fastabend@gmail.com>
Closes: https://syzkaller.appspot.com/bug?extid=ec941d6e24f633a59172
Link: https://lore.kernel.org/bpf/20240527-sockmap-verify-deletes-v1-1-944b372f2101@cloudflare.com
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2024-05-13
We've added 119 non-merge commits during the last 14 day(s) which contain
a total of 134 files changed, 9462 insertions(+), 4742 deletions(-).
The main changes are:
1) Add BPF JIT support for 32-bit ARCv2 processors, from Shahab Vahedi.
2) Add BPF range computation improvements to the verifier in particular
around XOR and OR operators, refactoring of checks for range computation
and relaxing MUL range computation so that src_reg can also be an unknown
scalar, from Cupertino Miranda.
3) Add support to attach kprobe BPF programs through kprobe_multi link in
a session mode, meaning, a BPF program is attached to both function entry
and return, the entry program can decide if the return program gets
executed and the entry program can share u64 cookie value with return
program. Session mode is a common use-case for tetragon and bpftrace,
from Jiri Olsa.
4) Fix a potential overflow in libbpf's ring__consume_n() and improve libbpf
as well as BPF selftest's struct_ops handling, from Andrii Nakryiko.
5) Improvements to BPF selftests in context of BPF gcc backend,
from Jose E. Marchesi & David Faust.
6) Migrate remaining BPF selftest tests from test_sock_addr.c to prog_test-
-style in order to retire the old test, run it in BPF CI and additionally
expand test coverage, from Jordan Rife.
7) Big batch for BPF selftest refactoring in order to remove duplicate code
around common network helpers, from Geliang Tang.
8) Another batch of improvements to BPF selftests to retire obsolete
bpf_tcp_helpers.h as everything is available vmlinux.h,
from Martin KaFai Lau.
9) Fix BPF map tear-down to not walk the map twice on free when both timer
and wq is used, from Benjamin Tissoires.
10) Fix BPF verifier assumptions about socket->sk that it can be non-NULL,
from Alexei Starovoitov.
11) Change BTF build scripts to using --btf_features for pahole v1.26+,
from Alan Maguire.
12) Small improvements to BPF reusing struct_size() and krealloc_array(),
from Andy Shevchenko.
13) Fix s390 JIT to emit a barrier for BPF_FETCH instructions,
from Ilya Leoshkevich.
14) Extend TCP ->cong_control() callback in order to feed in ack and
flag parameters and allow write-access to tp->snd_cwnd_stamp
from BPF program, from Miao Xu.
15) Add support for internal-only per-CPU instructions to inline
bpf_get_smp_processor_id() helper call for arm64 and riscv64 BPF JITs,
from Puranjay Mohan.
16) Follow-up to remove the redundant ethtool.h from tooling infrastructure,
from Tushar Vyavahare.
17) Extend libbpf to support "module:<function>" syntax for tracing
programs, from Viktor Malik.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (119 commits)
bpf: make list_for_each_entry portable
bpf: ignore expected GCC warning in test_global_func10.c
bpf: disable strict aliasing in test_global_func9.c
selftests/bpf: Free strdup memory in xdp_hw_metadata
selftests/bpf: Fix a few tests for GCC related warnings.
bpf: avoid gcc overflow warning in test_xdp_vlan.c
tools: remove redundant ethtool.h from tooling infra
selftests/bpf: Expand ATTACH_REJECT tests
selftests/bpf: Expand getsockname and getpeername tests
sefltests/bpf: Expand sockaddr hook deny tests
selftests/bpf: Expand sockaddr program return value tests
selftests/bpf: Retire test_sock_addr.(c|sh)
selftests/bpf: Remove redundant sendmsg test cases
selftests/bpf: Migrate ATTACH_REJECT test cases
selftests/bpf: Migrate expected_attach_type tests
selftests/bpf: Migrate wildcard destination rewrite test
selftests/bpf: Migrate sendmsg6 v4 mapped address tests
selftests/bpf: Migrate sendmsg deny test cases
selftests/bpf: Migrate WILDCARD_IP test
selftests/bpf: Handle SYSCALL_EPERM and SYSCALL_ENOTSUPP test cases
...
====================
Link: https://lore.kernel.org/r/20240513134114.17575-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Inline the calls to bpf_get_smp_processor_id() in the riscv bpf jit.
RISCV saves the pointer to the CPU's task_struct in the TP (thread
pointer) register. This makes it trivial to get the CPU's processor id.
As thread_info is the first member of task_struct, we can read the
processor id from TP + offsetof(struct thread_info, cpu).
RISCV64 JIT output for `call bpf_get_smp_processor_id`
======================================================
Before After
-------- -------
auipc t1,0x848c ld a5,32(tp)
jalr 604(t1)
mv a5,a0
Benchmark using [1] on Qemu.
./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc
+---------------+------------------+------------------+--------------+
| Name | Before | After | % change |
|---------------+------------------+------------------+--------------|
| glob-arr-inc | 1.077 ± 0.006M/s | 1.336 ± 0.010M/s | + 24.04% |
| arr-inc | 1.078 ± 0.002M/s | 1.332 ± 0.015M/s | + 23.56% |
| hash-inc | 0.494 ± 0.004M/s | 0.653 ± 0.001M/s | + 32.18% |
+---------------+------------------+------------------+--------------+
NOTE: This benchmark includes changes from this patch and the previous
patch that implemented the per-cpu insn.
[1] https://github.com/anakryiko/linux/commit/8dec900975ef
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Björn Töpel <bjorn@kernel.org>
Link: https://lore.kernel.org/r/20240502151854.9810-3-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
MUL instruction required that src_reg would be a known value (i.e.
src_reg would be a const value). The condition in this case can be
relaxed, since the range computation algorithm used in current code
already supports a proper range computation for any valid range value on
its operands.
Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: David Faust <david.faust@oracle.com>
Cc: Jose Marchesi <jose.marchesi@oracle.com>
Cc: Elena Zannoni <elena.zannoni@oracle.com>
Link: https://lore.kernel.org/r/20240506141849.185293-6-cupertino.miranda@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Range for XOR and OR operators would not be attempted unless src_reg
would resolve to a single value, i.e. a known constant value.
This condition is unnecessary, and the following XOR/OR operator
handling could compute a possible better range.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: David Faust <david.faust@oracle.com>
Cc: Jose Marchesi <jose.marchesi@oracle.com>
Cc: Elena Zannoni <elena.zannoni@oracle.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Link: https://lore.kernel.org/r/20240506141849.185293-4-cupertino.miranda@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Split range computation checks in its own function, isolating pessimitic
range set for dst_reg and failing return to a single point.
Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: David Faust <david.faust@oracle.com>
Cc: Jose Marchesi <jose.marchesi@oracle.com>
Cc: Elena Zannoni <elena.zannoni@oracle.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
bpf/verifier: improve code after range computation recent changes.
Link: https://lore.kernel.org/r/20240506141849.185293-3-cupertino.miranda@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In order to further simplify the code in adjust_scalar_min_max_vals all
the calls to mark_reg_unknown are replaced by __mark_reg_unknown.
static void mark_reg_unknown(struct bpf_verifier_env *env,
struct bpf_reg_state *regs, u32 regno)
{
if (WARN_ON(regno >= MAX_BPF_REG)) {
... mark all regs not init ...
return;
}
__mark_reg_unknown(env, regs + regno);
}
The 'regno >= MAX_BPF_REG' does not apply to
adjust_scalar_min_max_vals(), because it is only called from the
following stack:
- check_alu_op
- adjust_reg_min_max_vals
- adjust_scalar_min_max_vals
The check_alu_op() does check_reg_arg() which verifies that both src and
dst register numbers are within bounds.
Signed-off-by: Cupertino Miranda <cupertino.miranda@oracle.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Cc: Yonghong Song <yonghong.song@linux.dev>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: David Faust <david.faust@oracle.com>
Cc: Jose Marchesi <jose.marchesi@oracle.com>
Cc: Elena Zannoni <elena.zannoni@oracle.com>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Link: https://lore.kernel.org/r/20240506141849.185293-2-cupertino.miranda@oracle.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cross-merge networking fixes after downstream PR.
Conflicts:
include/linux/filter.h
kernel/bpf/core.c
66e13b615a ("bpf: verifier: prevent userspace memory access")
d503a04f8b ("bpf: Add support for certain atomics in bpf_arena to x86 JIT")
https://lore.kernel.org/all/20240429114939.210328b0@canb.auug.org.au/
No adjacent changes.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Adding support for cookie within the session of kprobe multi
entry and return program.
The session cookie is u64 value and can be retrieved be new
kfunc bpf_session_cookie, which returns pointer to the cookie
value. The bpf program can use the pointer to store (on entry)
and load (on return) the value.
The cookie value is implemented via fprobe feature that allows
to share values between entry and return ftrace fprobe callbacks.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240430112830.1184228-4-jolsa@kernel.org
The verifier assumes that 'sk' field in 'struct socket' is valid
and non-NULL when 'socket' pointer itself is trusted and non-NULL.
That may not be the case when socket was just created and
passed to LSM socket_accept hook.
Fix this verifier assumption and adjust tests.
Reported-by: Liam Wisehart <liamwisehart@meta.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fixes: 6fcd486b3a ("bpf: Refactor RCU enforcement in the verifier.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20240427002544.68803-1-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2024-04-29
We've added 147 non-merge commits during the last 32 day(s) which contain
a total of 158 files changed, 9400 insertions(+), 2213 deletions(-).
The main changes are:
1) Add an internal-only BPF per-CPU instruction for resolving per-CPU
memory addresses and implement support in x86 BPF JIT. This allows
inlining per-CPU array and hashmap lookups
and the bpf_get_smp_processor_id() helper, from Andrii Nakryiko.
2) Add BPF link support for sk_msg and sk_skb programs, from Yonghong Song.
3) Optimize x86 BPF JIT's emit_mov_imm64, and add support for various
atomics in bpf_arena which can be JITed as a single x86 instruction,
from Alexei Starovoitov.
4) Add support for passing mark with bpf_fib_lookup helper,
from Anton Protopopov.
5) Add a new bpf_wq API for deferring events and refactor sleepable
bpf_timer code to keep common code where possible,
from Benjamin Tissoires.
6) Fix BPF_PROG_TEST_RUN infra with regards to bpf_dummy_struct_ops programs
to check when NULL is passed for non-NULLable parameters,
from Eduard Zingerman.
7) Harden the BPF verifier's and/or/xor value tracking,
from Harishankar Vishwanathan.
8) Introduce crypto kfuncs to make BPF programs able to utilize the kernel
crypto subsystem, from Vadim Fedorenko.
9) Various improvements to the BPF instruction set standardization doc,
from Dave Thaler.
10) Extend libbpf APIs to partially consume items from the BPF ringbuffer,
from Andrea Righi.
11) Bigger batch of BPF selftests refactoring to use common network helpers
and to drop duplicate code, from Geliang Tang.
12) Support bpf_tail_call_static() helper for BPF programs with GCC 13,
from Jose E. Marchesi.
13) Add bpf_preempt_{disable,enable}() kfuncs in order to allow a BPF
program to have code sections where preemption is disabled,
from Kumar Kartikeya Dwivedi.
14) Allow invoking BPF kfuncs from BPF_PROG_TYPE_SYSCALL programs,
from David Vernet.
15) Extend the BPF verifier to allow different input maps for a given
bpf_for_each_map_elem() helper call in a BPF program, from Philo Lu.
16) Add support for PROBE_MEM32 and bpf_addr_space_cast instructions
for riscv64 and arm64 JITs to enable BPF Arena, from Puranjay Mohan.
17) Shut up a false-positive KMSAN splat in interpreter mode by unpoison
the stack memory, from Martin KaFai Lau.
18) Improve xsk selftest coverage with new tests on maximum and minimum
hardware ring size configurations, from Tushar Vyavahare.
19) Various ReST man pages fixes as well as documentation and bash completion
improvements for bpftool, from Rameez Rehman & Quentin Monnet.
20) Fix libbpf with regards to dumping subsequent char arrays,
from Quentin Deslandes.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (147 commits)
bpf, docs: Clarify PC use in instruction-set.rst
bpf_helpers.h: Define bpf_tail_call_static when building with GCC
bpf, docs: Add introduction for use in the ISA Internet Draft
selftests/bpf: extend BPF_SOCK_OPS_RTT_CB test for srtt and mrtt_us
bpf: add mrtt and srtt as BPF_SOCK_OPS_RTT_CB args
selftests/bpf: dummy_st_ops should reject 0 for non-nullable params
bpf: check bpf_dummy_struct_ops program params for test runs
selftests/bpf: do not pass NULL for non-nullable params in dummy_st_ops
selftests/bpf: adjust dummy_st_ops_success to detect additional error
bpf: mark bpf_dummy_struct_ops.test_1 parameter as nullable
selftests/bpf: Add ring_buffer__consume_n test.
bpf: Add bpf_guard_preempt() convenience macro
selftests: bpf: crypto: add benchmark for crypto functions
selftests: bpf: crypto skcipher algo selftests
bpf: crypto: add skcipher to bpf crypto
bpf: make common crypto API for TC/XDP programs
bpf: update the comment for BTF_FIELDS_MAX
selftests/bpf: Fix wq test.
selftests/bpf: Use make_sockaddr in test_sock_addr
selftests/bpf: Use connect_to_addr in test_sock_addr
...
====================
Link: https://lore.kernel.org/r/20240429131657.19423-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add crypto API support to BPF to be able to decrypt or encrypt packets
in TC/XDP BPF programs. Special care should be taken for initialization
part of crypto algo because crypto alloc) doesn't work with preemtion
disabled, it can be run only in sleepable BPF program. Also async crypto
is not supported because of the very same issue - TC/XDP BPF programs
are not sleepable.
Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
Link: https://lore.kernel.org/r/20240422225024.2847039-2-vadfed@meta.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Introduce two new BPF kfuncs, bpf_preempt_disable and
bpf_preempt_enable. These kfuncs allow disabling preemption in BPF
programs. Nesting is allowed, since the intended use cases includes
building native BPF spin locks without kernel helper involvement. Apart
from that, this can be used to per-CPU data structures for cases where
programs (or userspace) may preempt one or the other. Currently, while
per-CPU access is stable, whether it will be consistent is not
guaranteed, as only migration is disabled for BPF programs.
Global functions are disallowed from being called, but support for them
will be added as a follow up not just preempt kfuncs, but rcu_read_lock
kfuncs as well. Static subprog calls are permitted. Sleepable helpers
and kfuncs are disallowed in non-preemptible regions.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20240424031315.2757363-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
To support sleepable async callbacks, we need to tell push_async_cb()
whether the cb is sleepable or not.
The verifier now detects that we are in bpf_wq_set_callback_impl and
can allow a sleepable callback to happen.
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-13-6c986a5a741f@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Introduce support for KF_ARG_PTR_TO_WORKQUEUE. The kfuncs will use bpf_wq
as argument and that will be recognized as workqueue argument by verifier.
bpf_wq_kern casting can happen inside kfunc, but using bpf_wq in
argument makes life easier for users who work with non-kern type in BPF
progs.
Duplicate process_timer_func into process_wq_func.
meta argument is only needed to ensure bpf_wq_init's workqueue and map
arguments are coming from the same map (map_uid logic is necessary for
correct inner-map handling), so also amend check_kfunc_args() to
match what helpers functions check is doing.
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-8-6c986a5a741f@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When a kfunc is declared with a KF_ARG_PTR_TO_MAP, we should have
reg->map_ptr set to a non NULL value, otherwise, that means that the
underlying type is not a map.
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-7-6c986a5a741f@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Mostly a copy/paste from the bpf_timer API, without the initialization
and free, as they will be done in a separate patch.
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/20240420-bpf_wq-v2-5-6c986a5a741f@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Found the following typos in comments, and fixed them:
s/unpriviledged/unprivileged/
s/reponsible/responsible/
s/possiblities/possibilities/
s/Divison/Division/
s/precsion/precision/
s/havea/have a/
s/reponsible/responsible/
s/responsibile/responsible/
s/tigher/tighter/
s/respecitve/respective/
Signed-off-by: Rafael Passos <rafael@rcpassos.me>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/6af7deb4-bb24-49e8-b3f1-8dd410597337@smtp-relay.sendinblue.com
This patch addresses a latent unsoundness issue in the
scalar(32)_min_max_and/or/xor functions. While it is not a bugfix,
it ensures that the functions produce sound outputs for all inputs.
The issue occurs in these functions when setting signed bounds. The
following example illustrates the issue for scalar_min_max_and(),
but it applies to the other functions.
In scalar_min_max_and() the following clause is executed when ANDing
positive numbers:
/* ANDing two positives gives a positive, so safe to
* cast result into s64.
*/
dst_reg->smin_value = dst_reg->umin_value;
dst_reg->smax_value = dst_reg->umax_value;
However, if umin_value and umax_value of dst_reg cross the sign boundary
(i.e., if (s64)dst_reg->umin_value > (s64)dst_reg->umax_value), then we
will end up with smin_value > smax_value, which is unsound.
Previous works [1, 2] have discovered and reported this issue. Our tool
Agni [2, 3] consideres it a false positive. This is because, during the
verification of the abstract operator scalar_min_max_and(), Agni restricts
its inputs to those passing through reg_bounds_sync(). This mimics
real-world verifier behavior, as reg_bounds_sync() is invariably executed
at the tail of every abstract operator. Therefore, such behavior is
unlikely in an actual verifier execution.
However, it is still unsound for an abstract operator to set signed bounds
such that smin_value > smax_value. This patch fixes it, making the abstract
operator sound for all (well-formed) inputs.
It is worth noting that while the previous code updated the signed bounds
(using the output unsigned bounds) only when the *input signed* bounds
were positive, the new code updates them whenever the *output unsigned*
bounds do not cross the sign boundary.
An alternative approach to fix this latent unsoundness would be to
unconditionally set the signed bounds to unbounded [S64_MIN, S64_MAX], and
let reg_bounds_sync() refine the signed bounds using the unsigned bounds
and the tnum. We found that our approach produces more precise (tighter)
bounds.
For example, consider these inputs to BPF_AND:
/* dst_reg */
var_off.value: 8608032320201083347
var_off.mask: 615339716653692460
smin_value: 8070450532247928832
smax_value: 8070450532247928832
umin_value: 13206380674380886586
umax_value: 13206380674380886586
s32_min_value: -2110561598
s32_max_value: -133438816
u32_min_value: 4135055354
u32_max_value: 4135055354
/* src_reg */
var_off.value: 8584102546103074815
var_off.mask: 9862641527606476800
smin_value: 2920655011908158522
smax_value: 7495731535348625717
umin_value: 7001104867969363969
umax_value: 8584102543730304042
s32_min_value: -2097116671
s32_max_value: 71704632
u32_min_value: 1047457619
u32_max_value: 4268683090
After going through tnum_and() -> scalar32_min_max_and() ->
scalar_min_max_and() -> reg_bounds_sync(), our patch produces the following
bounds for s32:
s32_min_value: -1263875629
s32_max_value: -159911942
Whereas, setting the signed bounds to unbounded in scalar_min_max_and()
produces:
s32_min_value: -1263875629
s32_max_value: -1
As observed, our patch produces a tighter s32 bound. We also confirmed
using Agni and SMT verification that our patch always produces signed
bounds that are equal to or more precise than setting the signed bounds to
unbounded in scalar_min_max_and().
[1] https://sanjit-bhat.github.io/assets/pdf/ebpf-verifier-range-analysis22.pdf
[2] https://link.springer.com/chapter/10.1007/978-3-031-37709-9_12
[3] https://github.com/bpfverif/agni
Co-developed-by: Matan Shachnai <m.shachnai@rutgers.edu>
Signed-off-by: Matan Shachnai <m.shachnai@rutgers.edu>
Co-developed-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Signed-off-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Co-developed-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240402212039.51815-1-harishankar.vishwanathan@gmail.com
Link: https://lore.kernel.org/bpf/20240416115303.331688-1-harishankar.vishwanathan@gmail.com
Long ago a map file descriptor in a pseudo ldimm64 instruction could
only be present as an immediate value insn[0].imm, and thus this value
was used in a verbose verifier message printed when the file descriptor
wasn't valid. Since addition of BPF_PSEUDO_MAP_IDX_VALUE/BPF_PSEUDO_MAP_IDX
the insn[0].imm field can also contain an index pointing to the file
descriptor in the attr.fd_array array. However, if the file descriptor
is invalid, the verifier still prints the verbose message containing
value of insn[0].imm. Patch the verifier message to always print the
actual file descriptor value.
Fixes: 387544bfa2 ("bpf: Introduce fd_idx")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20240412141100.3562942-1-aspsk@isovalent.com
Support atomics in bpf_arena that can be JITed as a single x86 instruction.
Instructions that are JITed as loops are not supported at the moment,
since they require more complex extable and loop logic.
JITs can choose to do smarter things with bpf_jit_supports_insn().
Like arm64 may decide to support all bpf atomics instructions
when emit_lse_atomic is available and none in ll_sc mode.
bpf_jit_supports_percpu_insn(), bpf_jit_supports_ptr_xchg() and
other such callbacks can be replaced with bpf_jit_supports_insn()
in the future.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240405231134.17274-1-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Taking different maps within a single bpf_for_each_map_elem call is not
allowed before, because from the second map,
bpf_insn_aux_data->map_ptr_state will be marked as *poison*. In fact
both map_ptr and state are needed to support this use case: map_ptr is
used by set_map_elem_callback_state() while poison state is needed to
determine whether to use direct call.
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240405025536.18113-3-lulie@linux.alibaba.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, bpf_insn_aux_data->map_ptr_state is used to store either
map_ptr or its poison state (i.e., BPF_MAP_PTR_POISON). Thus
BPF_MAP_PTR_POISON must be checked before reading map_ptr. In certain
cases, we may need valid map_ptr even in case of poison state.
This will be explained in next patch with bpf_for_each_map_elem()
helper.
This patch changes map_ptr_state into a new struct including both map
pointer and its state (poison/unpriv). It's in the same union with
struct bpf_loop_inline_state, so there is no extra memory overhead.
Besides, macros BPF_MAP_PTR_UNPRIV/BPF_MAP_PTR_POISON/BPF_MAP_PTR are no
longer needed.
This patch does not change any existing functionality.
Signed-off-by: Philo Lu <lulie@linux.alibaba.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240405025536.18113-2-lulie@linux.alibaba.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The newly added code to handle bpf_get_branch_snapshot fails to link when
CONFIG_PERF_EVENTS is disabled:
aarch64-linux-ld: kernel/bpf/verifier.o: in function `do_misc_fixups':
verifier.c:(.text+0x1090c): undefined reference to `__SCK__perf_snapshot_branch_stack'
Add a build-time check for that Kconfig symbol around the code to
remove the link time dependency.
Fixes: 314a53623c ("bpf: inline bpf_get_branch_snapshot() helper")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20240405142637.577046-1-arnd@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
r10 is a special register that is not under BPF program's control and is
always effectively precise. The rest of precision logic assumes that
only r0-r9 SCALAR registers are marked as precise, so prevent r10 from
being marked precise.
This can happen due to signed cast instruction allowing to do something
like `r0 = (s8)r10;`, which later, if r0 needs to be precise, would lead
to an attempt to mark r10 as precise.
Prevent this with an extra check during instruction backtracking.
Fixes: 8100928c88 ("bpf: Support new sign-extension mov insns")
Reported-by: syzbot+148110ee7cf72f39f33e@syzkaller.appspotmail.com
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240404214536.3551295-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Inline bpf_get_branch_snapshot() helper using architecture-agnostic
inline BPF code which calls directly into underlying callback of
perf_snapshot_branch_stack static call. This callback is set early
during kernel initialization and is never updated or reset, so it's ok
to fetch actual implementation using static_call_query() and call
directly into it.
This change eliminates a full function call and saves one LBR entry
in PERF_SAMPLE_BRANCH_ANY LBR mode.
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240404002640.1774210-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When more than 64 maps are used by a program and its subprograms the
verifier returns -E2BIG. Add a verbose message which highlights the
source of the error and also print the actual limit.
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240402073347.195920-1-aspsk@isovalent.com
The resolve_pseudo_ldimm64() function might have leaked file
descriptors when BPF_MAP_TYPE_ARENA was used in a program (some
error paths missed a corresponding fdput). Add missing fdputs.
v2:
remove unrelated changes from the fix
Fixes: 6082b6c328 ("bpf: Recognize addr_space_cast instruction in the verifier.")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20240329071106.67968-1-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
BPF verifier emits "unknown func" message when given BPF program type
does not support BPF helper. This message may be confusing for users, as
important context that helper is unknown only to current program type is
not provided.
This patch changes message to "program of this type cannot use helper "
and aligns dependent code in libbpf and tests. Any suggestions on
improving/changing this message are welcome.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/r/20240325152210.377548-1-yatsenko@meta.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch re-introduces protection against the size of access to stack
memory being negative; the access size can appear negative as a result
of overflowing its signed int representation. This should not actually
happen, as there are other protections along the way, but we should
protect against it anyway. One code path was missing such protections
(fixed in the previous patch in the series), causing out-of-bounds array
accesses in check_stack_range_initialized(). This patch causes the
verification of a program with such a non-sensical access size to fail.
This check used to exist in a more indirect way, but was inadvertendly
removed in a833a17aea.
Fixes: a833a17aea ("bpf: Fix verification of indirect var-off stack access")
Reported-by: syzbot+33f4297b5f927648741a@syzkaller.appspotmail.com
Reported-by: syzbot+aafd0513053a1cbf52ef@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/CAADnVQLORV5PT0iTAhRER+iLBTkByCYNBYyvBSgjN1T31K+gOw@mail.gmail.com/
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Link: https://lore.kernel.org/r/20240327024245.318299-3-andreimatei1@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The verifier allows using the addr_space_cast instruction in a program
that doesn't have an associated arena. This was caught in the form an
invalid memory access in do_misc_fixups() when while converting
addr_space_cast to a normal 32-bit mov, env->prog->aux->arena was
dereferenced to check for BPF_F_NO_USER_CONV flag.
Reject programs that include the addr_space_cast instruction but don't
have an associated arena.
root@rv-tester:~# ./reproducer
Unable to handle kernel access to user memory without uaccess routines at virtual address 0000000000000030
Oops [#1]
[<ffffffff8017eeaa>] do_misc_fixups+0x43c/0x1168
[<ffffffff801936d6>] bpf_check+0xda8/0x22b6
[<ffffffff80174b32>] bpf_prog_load+0x486/0x8dc
[<ffffffff80176566>] __sys_bpf+0xbd8/0x214e
[<ffffffff80177d14>] __riscv_sys_bpf+0x22/0x2a
[<ffffffff80d2493a>] do_trap_ecall_u+0x102/0x17c
[<ffffffff80d3048c>] ret_from_exception+0x0/0x64
Fixes: 6082b6c328 ("bpf: Recognize addr_space_cast instruction in the verifier.")
Reported-by: xingwei lee <xrivendell7@gmail.com>
Reported-by: yue sun <samsun1006219@gmail.com>
Closes: https://lore.kernel.org/bpf/CABOYnLz09O1+2gGVJuCxd_24a-7UueXzV-Ff+Fr+h5EKFDiYCQ@mail.gmail.com/
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20240322153518.11555-1-puranjay12@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The verifier currently converts addr_space_cast from as(1) to as(0) that
is: BPF_ALU64 | BPF_MOV | BPF_X with off=1 and imm=1
to
BPF_ALU | BPF_MOV | BPF_X with imm=1 (32-bit mov)
Because of this imm=1, the JITs that have bpf_jit_needs_zext() == true,
interpret the converted instruction as BPF_ZEXT_REG(DST) which is a
special form of mov32, used for doing explicit zero extension on dst.
These JITs will just zero extend the dst reg and will not move the src to
dst before the zext.
Fix do_misc_fixups() to set imm=0 when converting addr_space_cast to a
normal mov32.
The JITs that have bpf_jit_needs_zext() == true rely on the verifier to
emit zext instructions. Mark dst_reg as subreg when doing cast from
as(1) to as(0) so the verifier emits a zext instruction after the mov.
Fixes: 6082b6c328 ("bpf: Recognize addr_space_cast instruction in the verifier.")
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20240321153939.113996-1-puranjay12@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In case of GE/GT/SGE/JST instructions, regs_refine_cond_op()
reuses the logic that does analysis of LE/LT/SLE/SLT instructions.
This commit avoids the use of a goto to perform the reuse.
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240321002955.808604-1-harishankar.vishwanathan@gmail.com
set_memory_ro() can fail, leaving memory unprotected.
Check its return and take it into account as an error.
Link: https://github.com/KSPP/linux/issues/7
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: linux-hardening@vger.kernel.org <linux-hardening@vger.kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Message-ID: <286def78955e04382b227cb3e4b6ba272a7442e3.1709850515.git.christophe.leroy@csgroup.eu>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Copy over main program's sleepable bit into subprog's info. This might
be important for, e.g., freplace cases.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Message-ID: <20240314000127.3881569-1-andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, the x86 JIT handling PROBE_MEM32 tagged accesses is not
equipped to handle atomic accesses into PTR_TO_ARENA, as no PROBE_MEM32
tagging is performed and no handling is enabled for them.
This will lead to unsafety as the offset into arena will dereferenced
directly without turning it into a base + offset access into the arena
region.
Since the changes to the x86 JIT will be fairly involved, for now,
temporarily disallow use of PTR_TO_ARENA as the destination operand for
atomics until support is added to the JIT backend.
Fixes: 2fe99eb0cc ("bpf: Add x86-64 JIT support for PROBE_MEM32 pseudo instructions.")
Reported-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Message-ID: <20240314174931.98702-1-puranjay12@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Alexei Starovoitov says:
====================
pull-request: bpf-next 2024-03-11
We've added 59 non-merge commits during the last 9 day(s) which contain
a total of 88 files changed, 4181 insertions(+), 590 deletions(-).
The main changes are:
1) Enforce VM_IOREMAP flag and range in ioremap_page_range and introduce
VM_SPARSE kind and vm_area_[un]map_pages to be used in bpf_arena,
from Alexei.
2) Introduce bpf_arena which is sparse shared memory region between bpf
program and user space where structures inside the arena can have
pointers to other areas of the arena, and pointers work seamlessly for
both user-space programs and bpf programs, from Alexei and Andrii.
3) Introduce may_goto instruction that is a contract between the verifier
and the program. The verifier allows the program to loop assuming it's
behaving well, but reserves the right to terminate it, from Alexei.
4) Use IETF format for field definitions in the BPF standard
document, from Dave.
5) Extend struct_ops libbpf APIs to allow specify version suffixes for
stuct_ops map types, share the same BPF program between several map
definitions, and other improvements, from Eduard.
6) Enable struct_ops support for more than one page in trampolines,
from Kui-Feng.
7) Support kCFI + BPF on riscv64, from Puranjay.
8) Use bpf_prog_pack for arm64 bpf trampoline, from Puranjay.
9) Fix roundup_pow_of_two undefined behavior on 32-bit archs, from Toke.
====================
Link: https://lore.kernel.org/r/20240312003646.8692-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
prog->aux->sleepable is checked very frequently as part of (some) BPF
program run hot paths. So this extra aux indirection seems wasteful and
on busy systems might cause unnecessary memory cache misses.
Let's move sleepable flag into prog itself to eliminate unnecessary
pointer dereference.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Message-ID: <20240309004739.2961431-1-andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In global bpf functions recognize btf_decl_tag("arg:arena") as PTR_TO_ARENA.
Note, when the verifier sees:
__weak void foo(struct bar *p)
it recognizes 'p' as PTR_TO_MEM and 'struct bar' has to be a struct with scalars.
Hence the only way to use arena pointers in global functions is to tag them with "arg:arena".
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20240308010812.89848-7-alexei.starovoitov@gmail.com
rY = addr_space_cast(rX, 0, 1) tells the verifier that rY->type = PTR_TO_ARENA.
Any further operations on PTR_TO_ARENA register have to be in 32-bit domain.
The verifier will mark load/store through PTR_TO_ARENA with PROBE_MEM32.
JIT will generate them as kern_vm_start + 32bit_addr memory accesses.
rY = addr_space_cast(rX, 1, 0) tells the verifier that rY->type = unknown scalar.
If arena->map_flags has BPF_F_NO_USER_CONV set then convert cast_user to mov32 as well.
Otherwise JIT will convert it to:
rY = (u32)rX;
if (rY)
rY |= arena->user_vm_start & ~(u64)~0U;
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240308010812.89848-6-alexei.starovoitov@gmail.com
Introduce bpf_arena, which is a sparse shared memory region between the bpf
program and user space.
Use cases:
1. User space mmap-s bpf_arena and uses it as a traditional mmap-ed
anonymous region, like memcached or any key/value storage. The bpf
program implements an in-kernel accelerator. XDP prog can search for
a key in bpf_arena and return a value without going to user space.
2. The bpf program builds arbitrary data structures in bpf_arena (hash
tables, rb-trees, sparse arrays), while user space consumes it.
3. bpf_arena is a "heap" of memory from the bpf program's point of view.
The user space may mmap it, but bpf program will not convert pointers
to user base at run-time to improve bpf program speed.
Initially, the kernel vm_area and user vma are not populated. User space
can fault in pages within the range. While servicing a page fault,
bpf_arena logic will insert a new page into the kernel and user vmas. The
bpf program can allocate pages from that region via
bpf_arena_alloc_pages(). This kernel function will insert pages into the
kernel vm_area. The subsequent fault-in from user space will populate that
page into the user vma. The BPF_F_SEGV_ON_FAULT flag at arena creation time
can be used to prevent fault-in from user space. In such a case, if a page
is not allocated by the bpf program and not present in the kernel vm_area,
the user process will segfault. This is useful for use cases 2 and 3 above.
bpf_arena_alloc_pages() is similar to user space mmap(). It allocates pages
either at a specific address within the arena or allocates a range with the
maple tree. bpf_arena_free_pages() is analogous to munmap(), which frees
pages and removes the range from the kernel vm_area and from user process
vmas.
bpf_arena can be used as a bpf program "heap" of up to 4GB. The speed of
bpf program is more important than ease of sharing with user space. This is
use case 3. In such a case, the BPF_F_NO_USER_CONV flag is recommended.
It will tell the verifier to treat the rX = bpf_arena_cast_user(rY)
instruction as a 32-bit move wX = wY, which will improve bpf prog
performance. Otherwise, bpf_arena_cast_user is translated by JIT to
conditionally add the upper 32 bits of user vm_start (if the pointer is not
NULL) to arena pointers before they are stored into memory. This way, user
space sees them as valid 64-bit pointers.
Diff https://github.com/llvm/llvm-project/pull/84410 enables LLVM BPF
backend generate the bpf_addr_space_cast() instruction to cast pointers
between address_space(1) which is reserved for bpf_arena pointers and
default address space zero. All arena pointers in a bpf program written in
C language are tagged as __attribute__((address_space(1))). Hence, clang
provides helpful diagnostics when pointers cross address space. Libbpf and
the kernel support only address_space == 1. All other address space
identifiers are reserved.
rX = bpf_addr_space_cast(rY, /* dst_as */ 1, /* src_as */ 0) tells the
verifier that rX->type = PTR_TO_ARENA. Any further operations on
PTR_TO_ARENA register have to be in the 32-bit domain. The verifier will
mark load/store through PTR_TO_ARENA with PROBE_MEM32. JIT will generate
them as kern_vm_start + 32bit_addr memory accesses. The behavior is similar
to copy_from_kernel_nofault() except that no address checks are necessary.
The address is guaranteed to be in the 4GB range. If the page is not
present, the destination register is zeroed on read, and the operation is
ignored on write.
rX = bpf_addr_space_cast(rY, 0, 1) tells the verifier that rX->type =
unknown scalar. If arena->map_flags has BPF_F_NO_USER_CONV set, then the
verifier converts such cast instructions to mov32. Otherwise, JIT will emit
native code equivalent to:
rX = (u32)rY;
if (rY)
rX |= clear_lo32_bits(arena->user_vm_start); /* replace hi32 bits in rX */
After such conversion, the pointer becomes a valid user pointer within
bpf_arena range. The user process can access data structures created in
bpf_arena without any additional computations. For example, a linked list
built by a bpf program can be walked natively by user space.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Barret Rhoden <brho@google.com>
Link: https://lore.kernel.org/bpf/20240308010812.89848-2-alexei.starovoitov@gmail.com
Recognize 'void *p__map' kfunc argument as 'struct bpf_map *p__map'.
It allows kfunc to have 'void *' argument for maps, since bpf progs
will call them as:
struct {
__uint(type, BPF_MAP_TYPE_ARENA);
...
} arena SEC(".maps");
bpf_kfunc_with_map(... &arena ...);
Underneath libbpf will load CONST_PTR_TO_MAP into the register via ld_imm64
insn. If kfunc was defined with 'struct bpf_map *' it would pass the
verifier as well, but bpf prog would need to type cast the argument
(void *)&arena, which is not clean.
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20240307031228.42896-3-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
When open code iterators, bpf_loop or may_goto are used the following two
states are equivalent and safe to prune the search:
cur state: fp-8_w=scalar(id=3,smin=umin=smin32=umin32=2,smax=umax=smax32=umax32=11,var_off=(0x0; 0xf))
old state: fp-8_rw=scalar(id=2,smin=umin=smin32=umin32=1,smax=umax=smax32=umax32=11,var_off=(0x0; 0xf))
In other words "exact" state match should ignore liveness and precision
marks, since open coded iterator logic didn't complete their propagation,
reg_old->type == NOT_INIT && reg_cur->type != NOT_INIT is also not safe to
prune while looping, but range_within logic that applies to scalars,
ptr_to_mem, map_value, pkt_ptr is safe to rely on.
Avoid doing such comparison when regular infinite loop detection logic is
used, otherwise bounded loop logic will declare such "infinite loop" as
false positive. Such example is in progs/verifier_loops1.c
not_an_inifinite_loop().
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240306031929.42666-3-alexei.starovoitov@gmail.com
Introduce may_goto instruction that from the verifier pov is similar to
open coded iterators bpf_for()/bpf_repeat() and bpf_loop() helper, but it
doesn't iterate any objects.
In assembly 'may_goto' is a nop most of the time until bpf runtime has to
terminate the program for whatever reason. In the current implementation
may_goto has a hidden counter, but other mechanisms can be used.
For programs written in C the later patch introduces 'cond_break' macro
that combines 'may_goto' with 'break' statement and has similar semantics:
cond_break is a nop until bpf runtime has to break out of this loop.
It can be used in any normal "for" or "while" loop, like
for (i = zero; i < cnt; cond_break, i++) {
The verifier recognizes that may_goto is used in the program, reserves
additional 8 bytes of stack, initializes them in subprog prologue, and
replaces may_goto instruction with:
aux_reg = *(u64 *)(fp - 40)
if aux_reg == 0 goto pc+off
aux_reg -= 1
*(u64 *)(fp - 40) = aux_reg
may_goto instruction can be used by LLVM to implement __builtin_memcpy,
__builtin_strcmp.
may_goto is not a full substitute for bpf_for() macro.
bpf_for() doesn't have induction variable that verifiers sees,
so 'i' in bpf_for(i, 0, 100) is seen as imprecise and bounded.
But when the code is written as:
for (i = 0; i < 100; cond_break, i++)
the verifier see 'i' as precise constant zero,
hence cond_break (aka may_goto) doesn't help to converge the loop.
A static or global variable can be used as a workaround:
static int zero = 0;
for (i = zero; i < 100; cond_break, i++) // works!
may_goto works well with arena pointers that don't need to be bounds
checked on access. Load/store from arena returns imprecise unbounded
scalar and loops with may_goto pass the verifier.
Reserve new opcode BPF_JMP | BPF_JCOND for may_goto insn.
JCOND stands for conditional pseudo jump.
Since goto_or_nop insn was proposed, it may use the same opcode.
may_goto vs goto_or_nop can be distinguished by src_reg:
code = BPF_JMP | BPF_JCOND
src_reg = 0 - may_goto
src_reg = 1 - goto_or_nop
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240306031929.42666-2-alexei.starovoitov@gmail.com
When comparing current and cached states verifier should consider
bpf_func_state->callback_depth. Current state cannot be pruned against
cached state, when current states has more iterations left compared to
cached state. Current state has more iterations left when it's
callback_depth is smaller.
Below is an example illustrating this bug, minimized from mailing list
discussion [0] (assume that BPF_F_TEST_STATE_FREQ is set).
The example is not a safe program: if loop_cb point (1) is followed by
loop_cb point (2), then division by zero is possible at point (4).
struct ctx {
__u64 a;
__u64 b;
__u64 c;
};
static void loop_cb(int i, struct ctx *ctx)
{
/* assume that generated code is "fallthrough-first":
* if ... == 1 goto
* if ... == 2 goto
* <default>
*/
switch (bpf_get_prandom_u32()) {
case 1: /* 1 */ ctx->a = 42; return 0; break;
case 2: /* 2 */ ctx->b = 42; return 0; break;
default: /* 3 */ ctx->c = 42; return 0; break;
}
}
SEC("tc")
__failure
__flag(BPF_F_TEST_STATE_FREQ)
int test(struct __sk_buff *skb)
{
struct ctx ctx = { 7, 7, 7 };
bpf_loop(2, loop_cb, &ctx, 0); /* 0 */
/* assume generated checks are in-order: .a first */
if (ctx.a == 42 && ctx.b == 42 && ctx.c == 7)
asm volatile("r0 /= 0;":::"r0"); /* 4 */
return 0;
}
Prior to this commit verifier built the following checkpoint tree for
this example:
.------------------------------------- Checkpoint / State name
| .-------------------------------- Code point number
| | .---------------------------- Stack state {ctx.a,ctx.b,ctx.c}
| | | .------------------- Callback depth in frame #0
v v v v
- (0) {7P,7P,7},depth=0
- (3) {7P,7P,7},depth=1
- (0) {7P,7P,42},depth=1
- (3) {7P,7,42},depth=2
- (0) {7P,7,42},depth=2 loop terminates because of depth limit
- (4) {7P,7,42},depth=0 predicted false, ctx.a marked precise
- (6) exit
(a) - (2) {7P,7,42},depth=2
- (0) {7P,42,42},depth=2 loop terminates because of depth limit
- (4) {7P,42,42},depth=0 predicted false, ctx.a marked precise
- (6) exit
(b) - (1) {7P,7P,42},depth=2
- (0) {42P,7P,42},depth=2 loop terminates because of depth limit
- (4) {42P,7P,42},depth=0 predicted false, ctx.{a,b} marked precise
- (6) exit
- (2) {7P,7,7},depth=1 considered safe, pruned using checkpoint (a)
(c) - (1) {7P,7P,7},depth=1 considered safe, pruned using checkpoint (b)
Here checkpoint (b) has callback_depth of 2, meaning that it would
never reach state {42,42,7}.
While checkpoint (c) has callback_depth of 1, and thus
could yet explore the state {42,42,7} if not pruned prematurely.
This commit makes forbids such premature pruning,
allowing verifier to explore states sub-tree starting at (c):
(c) - (1) {7,7,7P},depth=1
- (0) {42P,7,7P},depth=1
...
- (2) {42,7,7},depth=2
- (0) {42,42,7},depth=2 loop terminates because of depth limit
- (4) {42,42,7},depth=0 predicted true, ctx.{a,b,c} marked precise
- (5) division by zero
[0] https://lore.kernel.org/bpf/9b251840-7cb8-4d17-bd23-1fc8071d8eef@linux.dev/
Fixes: bb124da69c ("bpf: keep track of max number of bpf_loop callback iterations")
Suggested-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240222154121.6991-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2024-02-29
We've added 119 non-merge commits during the last 32 day(s) which contain
a total of 150 files changed, 3589 insertions(+), 995 deletions(-).
The main changes are:
1) Extend the BPF verifier to enable static subprog calls in spin lock
critical sections, from Kumar Kartikeya Dwivedi.
2) Fix confusing and incorrect inference of PTR_TO_CTX argument type
in BPF global subprogs, from Andrii Nakryiko.
3) Larger batch of riscv BPF JIT improvements and enabling inlining
of the bpf_kptr_xchg() for RV64, from Pu Lehui.
4) Allow skeleton users to change the values of the fields in struct_ops
maps at runtime, from Kui-Feng Lee.
5) Extend the verifier's capabilities of tracking scalars when they
are spilled to stack, especially when the spill or fill is narrowing,
from Maxim Mikityanskiy & Eduard Zingerman.
6) Various BPF selftest improvements to fix errors under gcc BPF backend,
from Jose E. Marchesi.
7) Avoid module loading failure when the module trying to register
a struct_ops has its BTF section stripped, from Geliang Tang.
8) Annotate all kfuncs in .BTF_ids section which eventually allows
for automatic kfunc prototype generation from bpftool, from Daniel Xu.
9) Several updates to the instruction-set.rst IETF standardization
document, from Dave Thaler.
10) Shrink the size of struct bpf_map resp. bpf_array,
from Alexei Starovoitov.
11) Initial small subset of BPF verifier prepwork for sleepable bpf_timer,
from Benjamin Tissoires.
12) Fix bpftool to be more portable to musl libc by using POSIX's
basename(), from Arnaldo Carvalho de Melo.
13) Add libbpf support to gcc in CORE macro definitions,
from Cupertino Miranda.
14) Remove a duplicate type check in perf_event_bpf_event,
from Florian Lehner.
15) Fix bpf_spin_{un,}lock BPF helpers to actually annotate them
with notrace correctly, from Yonghong Song.
16) Replace the deprecated bpf_lpm_trie_key 0-length array with flexible
array to fix build warnings, from Kees Cook.
17) Fix resolve_btfids cross-compilation to non host-native endianness,
from Viktor Malik.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (119 commits)
selftests/bpf: Test if shadow types work correctly.
bpftool: Add an example for struct_ops map and shadow type.
bpftool: Generated shadow variables for struct_ops maps.
libbpf: Convert st_ops->data to shadow type.
libbpf: Set btf_value_type_id of struct bpf_map for struct_ops.
bpf: Replace bpf_lpm_trie_key 0-length array with flexible array
bpf, arm64: use bpf_prog_pack for memory management
arm64: patching: implement text_poke API
bpf, arm64: support exceptions
arm64: stacktrace: Implement arch_bpf_stack_walk() for the BPF JIT
bpf: add is_async_callback_calling_insn() helper
bpf: introduce in_sleepable() helper
bpf: allow more maps in sleepable bpf programs
selftests/bpf: Test case for lacking CFI stub functions.
bpf: Check cfi_stubs before registering a struct_ops type.
bpf: Clarify batch lookup/lookup_and_delete semantics
bpf, docs: specify which BPF_ABS and BPF_IND fields were zero
bpf, docs: Fix typos in instruction-set.rst
selftests/bpf: update tcp_custom_syncookie to use scalar packet offset
bpf: Shrink size of struct bpf_map/bpf_array.
...
====================
Link: https://lore.kernel.org/r/20240301001625.8800-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Currently we have a special case for BPF_FUNC_timer_set_callback,
let's introduce a helper we can extend for the kfunc that will come in
a later patch
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/20240221-hid-bpf-sleepable-v3-3-1fb378ca6301@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
These 2 maps types are required for HID-BPF when a user wants to do
IO with a device from a sleepable tracing point.
Allowing BPF_MAP_TYPE_QUEUE (and therefore BPF_MAP_TYPE_STACK) allows
for a BPF program to prepare from an IRQ the list of HID commands to send
back to the device and then these commands can be retrieved from the
sleepable trace point.
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Link: https://lore.kernel.org/r/20240221-hid-bpf-sleepable-v3-1-1fb378ca6301@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
With latest llvm19, I hit the following selftest failures with
$ ./test_progs -j
libbpf: prog 'on_event': BPF program load failed: Permission denied
libbpf: prog 'on_event': -- BEGIN PROG LOAD LOG --
combined stack size of 4 calls is 544. Too large
verification time 1344153 usec
stack depth 24+440+0+32
processed 51008 insns (limit 1000000) max_states_per_insn 19 total_states 1467 peak_states 303 mark_read 146
-- END PROG LOAD LOG --
libbpf: prog 'on_event': failed to load: -13
libbpf: failed to load object 'strobemeta_subprogs.bpf.o'
scale_test:FAIL:expect_success unexpected error: -13 (errno 13)
#498 verif_scale_strobemeta_subprogs:FAIL
The verifier complains too big of the combined stack size (544 bytes) which
exceeds the maximum stack limit 512. This is a regression from llvm19 ([1]).
In the above error log, the original stack depth is 24+440+0+32.
To satisfy interpreter's need, in verifier the stack depth is adjusted to
32+448+32+32=544 which exceeds 512, hence the error. The same adjusted
stack size is also used for jit case.
But the jitted codes could use smaller stack size.
$ egrep -r stack_depth | grep round_up
arm64/net/bpf_jit_comp.c: ctx->stack_size = round_up(prog->aux->stack_depth, 16);
loongarch/net/bpf_jit.c: bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
powerpc/net/bpf_jit_comp.c: cgctx.stack_size = round_up(fp->aux->stack_depth, 16);
riscv/net/bpf_jit_comp32.c: round_up(ctx->prog->aux->stack_depth, STACK_ALIGN);
riscv/net/bpf_jit_comp64.c: bpf_stack_adjust = round_up(ctx->prog->aux->stack_depth, 16);
s390/net/bpf_jit_comp.c: u32 stack_depth = round_up(fp->aux->stack_depth, 8);
sparc/net/bpf_jit_comp_64.c: stack_needed += round_up(stack_depth, 16);
x86/net/bpf_jit_comp.c: EMIT3_off32(0x48, 0x81, 0xEC, round_up(stack_depth, 8));
x86/net/bpf_jit_comp.c: int tcc_off = -4 - round_up(stack_depth, 8);
x86/net/bpf_jit_comp.c: round_up(stack_depth, 8));
x86/net/bpf_jit_comp.c: int tcc_off = -4 - round_up(stack_depth, 8);
x86/net/bpf_jit_comp.c: EMIT3_off32(0x48, 0x81, 0xC4, round_up(stack_depth, 8));
In the above, STACK_ALIGN in riscv/net/bpf_jit_comp32.c is defined as 16.
So stack is aligned in either 8 or 16, x86/s390 having 8-byte stack alignment and
the rest having 16-byte alignment.
This patch calculates total stack depth based on 16-byte alignment if jit is requested.
For the above failing case, the new stack size will be 32+448+0+32=512 and no verification
failure. llvm19 regression will be discussed separately in llvm upstream.
The verifier change caused three test failures as these tests compared messages
with stack size. More specifically,
- test_global_funcs/global_func1: fail with interpreter mode and success with jit mode.
Adjusted stack sizes so both jit and interpreter modes will fail.
- async_stack_depth/{pseudo_call_check, async_call_root_check}: since jit and interpreter
will calculate different stack sizes, the failure msg is adjusted to omit those
specific stack size numbers.
[1] https://lore.kernel.org/bpf/32bde0f0-1881-46c9-931a-673be566c61d@linux.dev/
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20240214232951.4113094-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Return result of btf_get_prog_ctx_type() is never used and callers only
check NULL vs non-NULL case to determine if given type matches expected
PTR_TO_CTX type. So rename function to `btf_is_prog_ctx_type()` and
return a simple true/false. We'll use this simpler interface to handle
kprobe program type's special typedef case in the next patch.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240212233221.2575350-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Collect argument information from the type information of stub functions to
mark arguments of BPF struct_ops programs with PTR_MAYBE_NULL if they are
nullable. A nullable argument is annotated by suffixing "__nullable" at
the argument name of stub function.
For nullable arguments, this patch sets a struct bpf_ctx_arg_aux to label
their reg_type with PTR_TO_BTF_ID | PTR_TRUSTED | PTR_MAYBE_NULL. This
makes the verifier to check programs and ensure that they properly check
the pointer. The programs should check if the pointer is null before
accessing the pointed memory.
The implementer of a struct_ops type should annotate the arguments that can
be null. The implementer should define a stub function (empty) as a
placeholder for each defined operator. The name of a stub function should
be in the pattern "<st_op_type>__<operator name>". For example, for
test_maybe_null of struct bpf_testmod_ops, it's stub function name should
be "bpf_testmod_ops__test_maybe_null". You mark an argument nullable by
suffixing the argument name with "__nullable" at the stub function.
Since we already has stub functions for kCFI, we just reuse these stub
functions with the naming convention mentioned earlier. These stub
functions with the naming convention is only required if there are nullable
arguments to annotate. For functions having not nullable arguments, stub
functions are not necessary for the purpose of this patch.
This patch will prepare a list of struct bpf_ctx_arg_aux, aka arg_info, for
each member field of a struct_ops type. "arg_info" will be assigned to
"prog->aux->ctx_arg_info" of BPF struct_ops programs in
check_struct_ops_btf_id() so that it can be used by btf_ctx_access() later
to set reg_type properly for the verifier.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240209023750.1153905-4-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Move __kfunc_param_match_suffix() to btf.c and rename it as
btf_param_match_suffix(). It can be reused by bpf_struct_ops later.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240209023750.1153905-3-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Compiling with CONFIG_BPF_SYSCALL & !CONFIG_BPF_JIT throws the below
warning:
"WARN: resolve_btfids: unresolved symbol bpf_cpumask"
Fix it by adding the appropriate #ifdef.
Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Stanislav Fomichev <sdf@google.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/bpf/20240208100115.602172-1-hbathini@linux.ibm.com
Allow transferring an imbalanced RCU lock state between subprog calls
during verification. This allows patterns where a subprog call returns
with an RCU lock held, or a subprog call releases an RCU lock held by
the caller. Currently, the verifier would end up complaining if the RCU
lock is not released when processing an exit from a subprog, which is
non-ideal if its execution is supposed to be enclosed in an RCU read
section of the caller.
Instead, simply only check whether we are processing exit for frame#0
and do not complain on an active RCU lock otherwise. We only need to
update the check when processing BPF_EXIT insn, as copy_verifier_state
is already set up to do the right thing.
Suggested-by: David Vernet <void@manifault.com>
Tested-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: David Vernet <void@manifault.com>
Link: https://lore.kernel.org/r/20240205055646.1112186-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, calling any helpers, kfuncs, or subprogs except the graph
data structure (lists, rbtrees) API kfuncs while holding a bpf_spin_lock
is not allowed. One of the original motivations of this decision was to
force the BPF programmer's hand into keeping the bpf_spin_lock critical
section small, and to ensure the execution time of the program does not
increase due to lock waiting times. In addition to this, some of the
helpers and kfuncs may be unsafe to call while holding a bpf_spin_lock.
However, when it comes to subprog calls, atleast for static subprogs,
the verifier is able to explore their instructions during verification.
Therefore, it is similar in effect to having the same code inlined into
the critical section. Hence, not allowing static subprog calls in the
bpf_spin_lock critical section is mostly an annoyance that needs to be
worked around, without providing any tangible benefit.
Unlike static subprog calls, global subprog calls are not safe to permit
within the critical section, as the verifier does not explore them
during verification, therefore whether the same lock will be taken
again, or unlocked, cannot be ascertained.
Therefore, allow calling static subprogs within a bpf_spin_lock critical
section, and only reject it in case the subprog linkage is global.
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: David Vernet <void@manifault.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20240204222349.938118-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add PTR_TRUSTED | PTR_MAYBE_NULL modifiers for PTR_TO_BTF_ID to
check_reg_type() to support passing trusted nullable PTR_TO_BTF_ID
registers into global functions accepting `__arg_trusted __arg_nullable`
arguments. This hasn't been caught earlier because tests were either
passing known non-NULL PTR_TO_BTF_ID registers or known NULL (SCALAR)
registers.
When utilizing this functionality in complicated real-world BPF
application that passes around PTR_TO_BTF_ID_OR_NULL, it became apparent
that verifier rejects valid case because check_reg_type() doesn't handle
this case explicitly. Existing check_reg_type() logic is already
anticipating this combination, so we just need to explicitly list this
combo in the switch statement.
Fixes: e2b3c4ff5d ("bpf: add __arg_trusted global func arg tag")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240202190529.2374377-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When check_stack_read_fixed_off() reads value from an spi
all stack slots of which are set to STACK_{MISC,INVALID},
the destination register is set to unbound SCALAR_VALUE.
Exploit this fact by allowing stacksafe() to use a fake
unbound scalar register to compare 'mmmm mmmm' stack value
in old state vs spilled 64-bit scalar in current state
and vice versa.
Veristat results after this patch show some gains:
./veristat -C -e file,prog,states -f 'states_pct>10' not-opt after
File Program States (DIFF)
----------------------- --------------------- ---------------
bpf_overlay.o tail_rev_nodeport_lb4 -45 (-15.85%)
bpf_xdp.o tail_lb_ipv4 -541 (-19.57%)
pyperf100.bpf.o on_event -680 (-10.42%)
pyperf180.bpf.o on_event -2164 (-19.62%)
pyperf600.bpf.o on_event -9799 (-24.84%)
strobemeta.bpf.o on_event -9157 (-65.28%)
xdp_synproxy_kern.bpf.o syncookie_tc -54 (-19.29%)
xdp_synproxy_kern.bpf.o syncookie_xdp -74 (-24.50%)
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240127175237.526726-6-maxtram95@gmail.com
When the width of a fill is smaller than the width of the preceding
spill, the information about scalar boundaries can still be preserved,
as long as it's coerced to the right width (done by coerce_reg_to_size).
Even further, if the actual value fits into the fill width, the ID can
be preserved as well for further tracking of equal scalars.
Implement the above improvements, which makes narrowing fills behave the
same as narrowing spills and MOVs between registers.
Two tests are adjusted to accommodate for endianness differences and to
take into account that it's now allowed to do a narrowing fill from the
least significant bits.
reg_bounds_sync is added to coerce_reg_to_size to correctly adjust
umin/umax boundaries after the var_off truncation, for example, a 64-bit
value 0xXXXXXXXX00000000, when read as a 32-bit, gets umin = 0, umax =
0xFFFFFFFF, var_off = (0x0; 0xffffffff00000000), which needs to be
synced down to umax = 0, otherwise reg_bounds_sanity_check doesn't pass.
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240127175237.526726-4-maxtram95@gmail.com
Support the pattern where an unbounded scalar is spilled to the stack,
then boundary checks are performed on the src register, after which the
stack frame slot is refilled into a register.
Before this commit, the verifier didn't treat the src register and the
stack slot as related if the src register was an unbounded scalar. The
register state wasn't copied, the id wasn't preserved, and the stack
slot was marked as STACK_MISC. Subsequent boundary checks on the src
register wouldn't result in updating the boundaries of the spilled
variable on the stack.
After this commit, the verifier will preserve the bond between src and
dst even if src is unbounded, which permits to do boundary checks on src
and refill dst later, still remembering its boundaries. Such a pattern
is sometimes generated by clang when compiling complex long functions.
One test is adjusted to reflect that now unbounded scalars are tracked.
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20240127175237.526726-2-maxtram95@gmail.com
Add support for passing PTR_TO_BTF_ID registers to global subprogs.
Currently only PTR_TRUSTED flavor of PTR_TO_BTF_ID is supported.
Non-NULL semantics is assumed, so caller will be forced to prove
PTR_TO_BTF_ID can't be NULL.
Note, we disallow global subprogs to destroy passed in PTR_TO_BTF_ID
arguments, even the trusted one. We achieve that by not setting
ref_obj_id when validating subprog code. This basically enforces (in
Rust terms) borrowing semantics vs move semantics. Borrowing semantics
seems to be a better fit for isolated global subprog validation
approach.
Implementation-wise, we utilize existing logic for matching
user-provided BTF type to kernel-side BTF type, used by BPF CO-RE logic
and following same matching rules. We enforce a unique match for types.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240130000648.2144827-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
In bpf_struct_ops_map_alloc, it needs to check for NULL in the returned
pointer of bpf_get_btf_vmlinux() when CONFIG_DEBUG_INFO_BTF is not set.
ENOTSUPP is used to preserve the same behavior before the
struct_ops kmod support.
In the function check_struct_ops_btf_id(), instead of redoing the
bpf_get_btf_vmlinux() that has already been done in syscall.c, the fix
here is to check for prog->aux->attach_btf_id.
BPF_PROG_TYPE_STRUCT_OPS must require attach_btf_id and syscall.c
guarantees a valid attach_btf as long as attach_btf_id is set.
When attach_btf_id is not set, this patch returns -ENOTSUPP
because it is what the selftest in test_libbpf_probe_prog_types()
and libbpf_probes.c are expecting for feature probing purpose.
Changes from v1:
- Remove an unnecessary NULL check in check_struct_ops_btf_id()
Reported-by: syzbot+88f0aafe5f950d7489d7@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/00000000000040d68a060fc8db8c@google.com/
Reported-by: syzbot+1336f3d4b10bcda75b89@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/bpf/00000000000026353b060fc21c07@google.com/
Fixes: fcc2c1fb06 ("bpf: pass attached BTF to the bpf_struct_ops subsystem")
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240126023113.1379504-1-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Remove remaining direct queries to perfmon_capable() and bpf_capable()
in BPF verifier logic and instead use BPF token (if available) to make
decisions about privileges.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20240124022127.2379740-9-andrii@kernel.org
To ensure that a module remains accessible whenever a struct_ops object of
a struct_ops type provided by the module is still in use.
struct bpf_struct_ops_map doesn't hold a refcnt to btf anymore since a
module will hold a refcnt to it's btf already. But, struct_ops programs are
different. They hold their associated btf, not the module since they need
only btf to assure their types (signatures).
However, verifier holds the refcnt of the associated module of a struct_ops
type temporarily when verify a struct_ops prog. Verifier needs the help
from the verifier operators (struct bpf_verifier_ops) provided by the owner
module to verify data access of a prog, provide information, and generate
code.
This patch also add a count of links (links_cnt) to bpf_struct_ops_map. It
avoids bpf_struct_ops_map_put_progs() from accessing btf after calling
module_put() in bpf_struct_ops_map_free().
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-10-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Pass the fd of a btf from the userspace to the bpf() syscall, and then
convert the fd into a btf. The btf is generated from the module that
defines the target BPF struct_ops type.
In order to inform the kernel about the module that defines the target
struct_ops type, the userspace program needs to provide a btf fd for the
respective module's btf. This btf contains essential information on the
types defined within the module, including the target struct_ops type.
A btf fd must be provided to the kernel for struct_ops maps and for the bpf
programs attached to those maps.
In the case of the bpf programs, the attach_btf_obj_fd parameter is passed
as part of the bpf_attr and is converted into a btf. This btf is then
stored in the prog->aux->attach_btf field. Here, it just let the verifier
access attach_btf directly.
In the case of struct_ops maps, a btf fd is passed as value_type_btf_obj_fd
of bpf_attr. The bpf_struct_ops_map_alloc() function converts the fd to a
btf and stores it as st_map->btf. A flag BPF_F_VTYPE_BTF_OBJ_FD is added
for map_flags to indicate that the value of value_type_btf_obj_fd is set.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-9-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
This is a preparation for searching for struct_ops types from a specified
module. BTF is always btf_vmlinux now. This patch passes a pointer of BTF
to bpf_struct_ops_find_value() and bpf_struct_ops_find(). Once the new
registration API of struct_ops types is used, other BTFs besides
btf_vmlinux can also be passed to them.
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-8-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Move some of members of bpf_struct_ops to bpf_struct_ops_desc. type_id is
unavailabe in bpf_struct_ops anymore. Modules should get it from the btf
received by kmod's init function.
Cc: netdev@vger.kernel.org
Signed-off-by: Kui-Feng Lee <thinker.li@gmail.com>
Link: https://lore.kernel.org/r/20240119225005.668602-4-thinker.li@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Current checking rules are structured to disallow alu on particular ptr
types explicitly, so default cases are allowed implicitly. This may lead
to newly added ptr types being allowed unexpectedly. So restruture it to
allow alu explicitly. The tradeoff is mainly a bit more cases added in
the switch. The following table from Eduard summarizes the rules:
| Pointer type | Arithmetics allowed |
|---------------------+---------------------|
| PTR_TO_CTX | yes |
| CONST_PTR_TO_MAP | conditionally |
| PTR_TO_MAP_VALUE | yes |
| PTR_TO_MAP_KEY | yes |
| PTR_TO_STACK | yes |
| PTR_TO_PACKET_META | yes |
| PTR_TO_PACKET | yes |
| PTR_TO_PACKET_END | no |
| PTR_TO_FLOW_KEYS | conditionally |
| PTR_TO_SOCKET | no |
| PTR_TO_SOCK_COMMON | no |
| PTR_TO_TCP_SOCK | no |
| PTR_TO_TP_BUFFER | yes |
| PTR_TO_XDP_SOCK | no |
| PTR_TO_BTF_ID | yes |
| PTR_TO_MEM | yes |
| PTR_TO_BUF | yes |
| PTR_TO_FUNC | yes |
| CONST_PTR_TO_DYNPTR | yes |
The refactored rules are equivalent to the original one. Note that
PTR_TO_FUNC and CONST_PTR_TO_DYNPTR are not reject here because: (1)
check_mem_access() rejects load/store on those ptrs, and those ptrs
with offset passing to calls are rejected check_func_arg_reg_off();
(2) someone may rely on the verifier not rejecting programs earily.
Signed-off-by: Hao Sun <sunhao.th@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240117094012.36798-1-sunhao.th@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
With patch set [1], precision backtracing supports register spill/fill
to/from the stack. The patch [2] allows initial imprecise register spill
with content 0. This is a common case for cpuv3 and lower for
initializing the stack variables with pattern
r1 = 0
*(u64 *)(r10 - 8) = r1
and the [2] has demonstrated good verification improvement.
For cpuv4, the initialization could be
*(u64 *)(r10 - 8) = 0
The current verifier marks the r10-8 contents with STACK_ZERO.
Similar to [2], let us permit the above insn to behave like
imprecise register spill which can reduce number of verified states.
The change is in function check_stack_write_fixed_off().
Before this patch, spilled zero will be marked as STACK_ZERO
which can provide precise values. In check_stack_write_var_off(),
STACK_ZERO will be maintained if writing a const zero
so later it can provide precise values if needed.
The above handling of '*(u64 *)(r10 - 8) = 0' as a spill
will have issues in check_stack_write_var_off() as the spill
will be converted to STACK_MISC and the precise value 0
is lost. To fix this issue, if the spill slots with const
zero and the BPF_ST write also with const zero, the spill slots
are preserved, which can later provide precise values
if needed. Without the change in check_stack_write_var_off(),
the test_verifier subtest 'BPF_ST_MEM stack imm zero, variable offset'
will fail.
I checked cpuv3 and cpuv4 with and without this patch with veristat.
There is no state change for cpuv3 since '*(u64 *)(r10 - 8) = 0'
is only generated with cpuv4.
For cpuv4:
$ ../veristat -C old.cpuv4.csv new.cpuv4.csv -e file,prog,insns,states -f 'insns_diff!=0'
File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF)
------------------------------------------ ------------------- --------- --------- --------------- ---------- ---------- -------------
local_storage_bench.bpf.linked3.o get_local 228 168 -60 (-26.32%) 17 14 -3 (-17.65%)
pyperf600_bpf_loop.bpf.linked3.o on_event 6066 4889 -1177 (-19.40%) 403 321 -82 (-20.35%)
test_cls_redirect.bpf.linked3.o cls_redirect 35483 35387 -96 (-0.27%) 2179 2177 -2 (-0.09%)
test_l4lb_noinline.bpf.linked3.o balancer_ingress 4494 4522 +28 (+0.62%) 217 219 +2 (+0.92%)
test_l4lb_noinline_dynptr.bpf.linked3.o balancer_ingress 1432 1455 +23 (+1.61%) 92 94 +2 (+2.17%)
test_xdp_noinline.bpf.linked3.o balancer_ingress_v6 3462 3458 -4 (-0.12%) 216 216 +0 (+0.00%)
verifier_iterating_callbacks.bpf.linked3.o widening 52 41 -11 (-21.15%) 4 3 -1 (-25.00%)
xdp_synproxy_kern.bpf.linked3.o syncookie_tc 12412 11719 -693 (-5.58%) 345 330 -15 (-4.35%)
xdp_synproxy_kern.bpf.linked3.o syncookie_xdp 12478 11794 -684 (-5.48%) 346 331 -15 (-4.34%)
test_l4lb_noinline and test_l4lb_noinline_dynptr has minor regression, but
pyperf600_bpf_loop and local_storage_bench gets pretty good improvement.
[1] https://lore.kernel.org/all/20231205184248.1502704-1-andrii@kernel.org/
[2] https://lore.kernel.org/all/20231205184248.1502704-9-andrii@kernel.org/
Cc: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Tested-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20240110051348.2737007-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, when a scalar bounded register is spilled to the stack, its
ID is preserved, but only if was already assigned, i.e. if this register
was MOVed before.
Assign an ID on spill if none is set, so that equal scalars could be
tracked if a register is spilled to the stack and filled into another
register.
One test is adjusted to reflect the change in register IDs.
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240108205209.838365-9-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Put calculation of the register value width into a dedicated function.
This function will also be used in a following commit.
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Link: https://lore.kernel.org/r/20240108205209.838365-8-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Extract the common code that generates a register ID for src_reg before
MOV if needed into a new function. This function will also be used in
a following commit.
Signed-off-by: Maxim Mikityanskiy <maxim@isovalent.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240108205209.838365-7-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Current infinite loops detection mechanism is speculative:
- first, states_maybe_looping() check is done which simply does memcmp
for R1-R10 in current frame;
- second, states_equal(..., exact=false) is called. With exact=false
states_equal() would compare scalars for equality only if in old
state scalar has precision mark.
Such logic might be problematic if compiler makes some unlucky stack
spill/fill decisions. An artificial example of a false positive looks
as follows:
r0 = ... unknown scalar ...
r0 &= 0xff;
*(u64 *)(r10 - 8) = r0;
r0 = 0;
loop:
r0 = *(u64 *)(r10 - 8);
if r0 > 10 goto exit_;
r0 += 1;
*(u64 *)(r10 - 8) = r0;
r0 = 0;
goto loop;
This commit updates call to states_equal to use exact=true, forcing
all scalar comparisons to be exact.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240108205209.838365-3-maxtram95@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add btf_arg_tag flags enum to be able to record multiple tags per
argument. Also streamline pointer argument processing some more.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20240105000909.2818934-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The motivation of inlining bpf_kptr_xchg() comes from the performance
profiling of bpf memory allocator benchmark. The benchmark uses
bpf_kptr_xchg() to stash the allocated objects and to pop the stashed
objects for free. After inling bpf_kptr_xchg(), the performance for
object free on 8-CPUs VM increases about 2%~10%. The inline also has
downside: both the kasan and kcsan checks on the pointer will be
unavailable.
bpf_kptr_xchg() can be inlined by converting the calling of
bpf_kptr_xchg() into an atomic_xchg() instruction. But the conversion
depends on two conditions:
1) JIT backend supports atomic_xchg() on pointer-sized word
2) For the specific arch, the implementation of xchg is the same as
atomic_xchg() on pointer-sized words.
It seems most 64-bit JIT backends satisfies these two conditions. But
as a precaution, defining a weak function bpf_jit_supports_ptr_xchg()
to state whether such conversion is safe and only supporting inline for
64-bit host.
For x86-64, it supports BPF_XCHG atomic operation and both xchg() and
atomic_xchg() use arch_xchg() to implement the exchange, so enabling the
inline of bpf_kptr_xchg() on x86-64 first.
Reviewed-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20240105104819.3916743-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, it's not allowed to attach an fentry/fexit prog to another
one fentry/fexit. At the same time it's not uncommon to see a tracing
program with lots of logic in use, and the attachment limitation
prevents usage of fentry/fexit for performance analysis (e.g. with
"bpftool prog profile" command) in this case. An example could be
falcosecurity libs project that uses tp_btf tracing programs.
Following the corresponding discussion [1], the reason for that is to
avoid tracing progs call cycles without introducing more complex
solutions. But currently it seems impossible to load and attach tracing
programs in a way that will form such a cycle. The limitation is coming
from the fact that attach_prog_fd is specified at the prog load (thus
making it impossible to attach to a program loaded after it in this
way), as well as tracing progs not implementing link_detach.
Replace "no same type" requirement with verification that no more than
one level of attachment nesting is allowed. In this way only one
fentry/fexit program could be attached to another fentry/fexit to cover
profiling use case, and still no cycle could be formed. To implement,
add a new field into bpf_prog_aux to track nested attachment for tracing
programs.
[1]: https://lore.kernel.org/bpf/20191108064039.2041889-16-ast@kernel.org/
Acked-by: Jiri Olsa <olsajiri@gmail.com>
Acked-by: Song Liu <song@kernel.org>
Signed-off-by: Dmitrii Dolgov <9erthalion6@gmail.com>
Link: https://lore.kernel.org/r/20240103190559.14750-2-9erthalion6@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
For percpu data structure allocation with bpf_global_percpu_ma,
the maximum data size is 4K. But for a system with large
number of cpus, bigger data size (e.g., 2K, 4K) might consume
a lot of memory. For example, the percpu memory consumption
with unit size 2K and 1024 cpus will be 2K * 1K * 1k = 2GB
memory.
We should discourage such usage. Let us limit the maximum data
size to be 512 for bpf_global_percpu_ma allocation.
Acked-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231222031801.1290841-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit 41a5db8d81 ("Add support for non-fix-size percpu mem allocation")
added support for non-fix-size percpu memory allocation.
Such allocation will allocate percpu memory for all buckets on all
cpus and the memory consumption is in the order to quadratic.
For example, let us say, 4 cpus, unit size 16 bytes, so each
cpu has 16 * 4 = 64 bytes, with 4 cpus, total will be 64 * 4 = 256 bytes.
Then let us say, 8 cpus with the same unit size, each cpu
has 16 * 8 = 128 bytes, with 8 cpus, total will be 128 * 8 = 1024 bytes.
So if the number of cpus doubles, the number of memory consumption
will be 4 times. So for a system with large number of cpus, the
memory consumption goes up quickly with quadratic order.
For example, for 4KB percpu allocation, 128 cpus. The total memory
consumption will 4KB * 128 * 128 = 64MB. Things will become
worse if the number of cpus is bigger (e.g., 512, 1024, etc.)
In Commit 41a5db8d81, the non-fix-size percpu memory allocation is
done in boot time, so for system with large number of cpus, the initial
percpu memory consumption is very visible. For example, for 128 cpu
system, the total percpu memory allocation will be at least
(16 + 32 + 64 + 96 + 128 + 196 + 256 + 512 + 1024 + 2048 + 4096)
* 128 * 128 = ~138MB.
which is pretty big. It will be even bigger for larger number of cpus.
Note that the current prefill also allocates 4 entries if the unit size
is less than 256. So on top of 138MB memory consumption, this will
add more consumption with
3 * (16 + 32 + 64 + 96 + 128 + 196 + 256) * 128 * 128 = ~38MB.
Next patch will try to reduce this memory consumption.
Later on, Commit 1fda5bb66a ("bpf: Do not allocate percpu memory
at init stage") moved the non-fix-size percpu memory allocation
to bpf verificaiton stage. Once a particular bpf_percpu_obj_new()
is called by bpf program, the memory allocator will try to fill in
the cache with all sizes, causing the same amount of percpu memory
consumption as in the boot stage.
To reduce the initial percpu memory consumption for non-fix-size
percpu memory allocation, instead of filling the cache with all
supported allocation sizes, this patch intends to fill the cache
only for the requested size. As typically users will not use large
percpu data structure, this can save memory significantly.
For example, the allocation size is 64 bytes with 128 cpus.
Then total percpu memory amount will be 64 * 128 * 128 = 1MB,
much less than previous 138MB.
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231222031745.1289082-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch simplifies the verification of size arguments associated to
pointer arguments to helpers and kfuncs. Many helpers take a pointer
argument followed by the size of the memory access performed to be
performed through that pointer. Before this patch, the handling of the
size argument in check_mem_size_reg() was confusing and wasteful: if the
size register's lower bound was 0, then the verification was done twice:
once considering the size of the access to be the lower-bound of the
respective argument, and once considering the upper bound (even if the
two are the same). The upper bound checking is a super-set of the
lower-bound checking(*), except: the only point of the lower-bound check
is to handle the case where zero-sized-accesses are explicitly not
allowed and the lower-bound is zero. This static condition is now
checked explicitly, replacing a much more complex, expensive and
confusing verification call to check_helper_mem_access().
Error messages change in this patch. Before, messages about illegal
zero-size accesses depended on the type of the pointer and on other
conditions, and sometimes the message was plain wrong: in some tests
that changed you'll see that the old message was something like "R1 min
value is outside of the allowed memory range", where R1 is the pointer
register; the error was wrongly claiming that the pointer was bad
instead of the size being bad. Other times the information that the size
came for a register with a possible range of values was wrong, and the
error presented the size as a fixed zero. Now the errors refer to the
right register. However, the old error messages did contain useful
information about the pointer register which is now lost; recovering
this information was deemed not important enough.
(*) Besides standing to reason that the checks for a bigger size access
are a super-set of the checks for a smaller size access, I have also
mechanically verified this by reading the code for all types of
pointers. I could convince myself that it's true for all but
PTR_TO_BTF_ID (check_ptr_to_btf_access). There, simply looking
line-by-line does not immediately prove what we want. If anyone has any
qualms, let me know.
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231221232225.568730-2-andreimatei1@gmail.com
Although it does not seem to have any untoward side-effects, the use
of ';' to separate to assignments seems more appropriate than ','.
Flagged by clang-17 -Wcomma
No functional change intended. Compile tested only.
Signed-off-by: Simon Horman <horms@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/bpf/20231221-bpf-verifier-comma-v1-1-cde2530912e9@kernel.org
Add ability to pass a pointer to dynptr into global functions.
This allows to have global subprogs that accept and work with generic
dynptrs that are created by caller. Dynptr argument is detected based on
the name of a struct type, if it's "bpf_dynptr", it's assumed to be
a proper dynptr pointer. Both actual struct and forward struct
declaration types are supported.
This is conceptually exactly the same semantics as
bpf_user_ringbuf_drain()'s use of dynptr to pass a variable-sized
pointer to ringbuf record. So we heavily rely on CONST_PTR_TO_DYNPTR
bits of already existing logic in the verifier.
During global subprog validation, we mark such CONST_PTR_TO_DYNPTR as
having LOCAL type, as that's the most unassuming type of dynptr and it
doesn't have any special helpers that can try to free or acquire extra
references (unlike skb, xdp, or ringbuf dynptr). So that seems like a safe
"choice" to make from correctness standpoint. It's still possible to
pass any type of dynptr to such subprog, though, because generic dynptr
helpers, like getting data/slice pointers, read/write memory copying
routines, dynptr adjustment and getter routines all work correctly with
any type of dynptr.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Add support for annotating global BPF subprog arguments to provide more
information about expected semantics of the argument. Currently,
verifier relies purely on argument's BTF type information, and supports
three general use cases: scalar, pointer-to-context, and
pointer-to-fixed-size-memory.
Scalar and pointer-to-fixed-mem work well in practice and are quite
natural to use. But pointer-to-context is a bit problematic, as typical
BPF users don't realize that they need to use a special type name to
signal to verifier that argument is not just some pointer, but actually
a PTR_TO_CTX. Further, even if users do know which type to use, it is
limiting in situations where the same BPF program logic is used across
few different program types. Common case is kprobes, tracepoints, and
perf_event programs having a helper to send some data over BPF perf
buffer. bpf_perf_event_output() requires `ctx` argument, and so it's
quite cumbersome to share such global subprog across few BPF programs of
different types, necessitating extra static subprog that is context
type-agnostic.
Long story short, there is a need to go beyond types and allow users to
add hints to global subprog arguments to define expectations.
This patch adds such support for two initial special tags:
- pointer to context;
- non-null qualifier for generic pointer arguments.
All of the above came up in practice already and seem generally useful
additions. Non-null qualifier is an often requested feature, which
currently has to be worked around by having unnecessary NULL checks
inside subprogs even if we know that arguments are never NULL. Pointer
to context was discussed earlier.
As for implementation, we utilize btf_decl_tag attribute and set up an
"arg:xxx" convention to specify argument hint. As such:
- btf_decl_tag("arg:ctx") is a PTR_TO_CTX hint;
- btf_decl_tag("arg:nonnull") marks pointer argument as not allowed to
be NULL, making NULL check inside global subprog unnecessary.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Remove duplicated BTF parsing logic when it comes to subprog call check.
Instead, use (potentially cached) results of btf_prepare_func_args() to
abstract away expectations of each subprog argument in generic terms
(e.g., "this is pointer to context", or "this is a pointer to memory of
size X"), and then use those simple high-level argument type
expectations to validate actual register states to check if they match
expectations.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-6-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Subprog call logic in btf_check_subprog_call() currently has both a lot
of BTF parsing logic (which is, presumably, what justified putting it
into btf.c), but also a bunch of register state checks, some of each
utilize deep verifier logic helpers, necessarily exported from
verifier.c: check_ptr_off_reg(), check_func_arg_reg_off(),
and check_mem_reg().
Going forward, btf_check_subprog_call() will have a minimum of
BTF-related logic, but will get more internal verifier logic related to
register state manipulation. So move it into verifier.c to minimize
amount of verifier-specific logic exposed to btf.c.
We do this move before refactoring btf_check_func_arg_match() to
preserve as much history post-refactoring as possible.
No functional changes.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Generalize btf_prepare_func_args() to support both global and static
subprogs. We are going to utilize this property in the next patch,
reusing btf_prepare_func_args() for subprog call logic instead of
reparsing BTF information in a completely separate implementation.
btf_prepare_func_args() now detects whether subprog is global or static
makes slight logic adjustments for static func cases, like not failing
fatally (-EFAULT) for conditions that are allowable for static subprogs.
Somewhat subtle (but major!) difference is the handling of pointer arguments.
Both global and static functions need to handle special context
arguments (which are pointers to predefined type names), but static
subprogs give up on any other pointers, falling back to marking subprog
as "unreliable", disabling the use of BTF type information altogether.
For global functions, though, we are assuming that such pointers to
unrecognized types are just pointers to fixed-sized memory region (or
error out if size cannot be established, like for `void *` pointers).
This patch accommodates these small differences and sets up a stage for
refactoring in the next patch, eliminating a separate BTF-based parsing
logic in btf_check_func_arg_match().
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of btf_check_subprog_arg_match(), use btf_prepare_func_args()
logic to validate "trustworthiness" of main BPF program's BTF information,
if it is present.
We ignored results of original BTF check anyway, often times producing
confusing and ominously-sounding "reg type unsupported for arg#0
function" message, which has no apparent effect on program correctness
and verification process.
All the -EFAULT returning sanity checks are already performed in
check_btf_info_early(), so there is zero reason to have this duplication
of logic between btf_check_subprog_call() and btf_check_subprog_arg_match().
Dropping btf_check_subprog_arg_match() simplifies
btf_check_func_arg_match() further removing `bool processing_call` flag.
One subtle bit that was done by btf_check_subprog_arg_match() was
potentially marking main program's BTF as unreliable. We do this
explicitly now with a dedicated simple check, preserving the original
behavior, but now based on well factored btf_prepare_func_args() logic.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
btf_prepare_func_args() is used to understand expectations and
restrictions on global subprog arguments. But current implementation is
hard to extend, as it intermixes BTF-based func prototype parsing and
interpretation logic with setting up register state at subprog entry.
Worse still, those registers are not completely set up inside
btf_prepare_func_args(), requiring some more logic later in
do_check_common(). Like calling mark_reg_unknown() and similar
initialization operations.
This intermixing of BTF interpretation and register state setup is
problematic. First, it causes duplication of BTF parsing logic for global
subprog verification (to set up initial state of global subprog) and
global subprog call sites analysis (when we need to check that whatever
is being passed into global subprog matches expectations), performed in
btf_check_subprog_call().
Given we want to extend global func argument with tags later, this
duplication is problematic. So refactor btf_prepare_func_args() to do
only BTF-based func proto and args parsing, returning high-level
argument "expectations" only, with no regard to specifics of register
state. I.e., if it's a context argument, instead of setting register
state to PTR_TO_CTX, we return ARG_PTR_TO_CTX enum for that argument as
"an argument specification" for further processing inside
do_check_common(). Similarly for SCALAR arguments, PTR_TO_MEM, etc.
This allows to reuse btf_prepare_func_args() in following patches at
global subprog call site analysis time. It also keeps register setup
code consistently in one place, do_check_common().
Besides all this, we cache this argument specs information inside
env->subprog_info, eliminating the need to redo these potentially
expensive BTF traversals, especially if BPF program's BTF is big and/or
there are lots of global subprog calls.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231215011334.2307144-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
We can derive some new information for BPF_JNE in regs_refine_cond_op().
Take following code for example:
/* The type of "a" is u32 */
if (a > 0 && a < 100) {
/* the range of the register for a is [0, 99], not [1, 99],
* and will cause the following error:
*
* invalid zero-sized read
*
* as a can be 0.
*/
bpf_skb_store_bytes(skb, xx, xx, a, 0);
}
In the code above, "a > 0" will be compiled to "jmp xxx if a == 0". In the
TRUE branch, the dst_reg will be marked as known to 0. However, in the
fallthrough(FALSE) branch, the dst_reg will not be handled, which makes
the [min, max] for a is [0, 99], not [1, 99].
For BPF_JNE, we can reduce the range of the dst reg if the src reg is a
const and is exactly the edge of the dst reg.
Signed-off-by: Menglong Dong <menglong8.dong@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Link: https://lore.kernel.org/r/20231219134800.1550388-2-menglong8.dong@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
It is safe to always start with imprecise SCALAR_VALUE register.
Previously __mark_reg_const_zero() relied on caller to reset precise
mark, but it's very error prone and we already missed it in a few
places. So instead make __mark_reg_const_zero() reset precision always,
as it's a safe default for SCALAR_VALUE. Explanation is basically the
same as for why we are resetting (or rather not setting) precision in
current state. If necessary, precision propagation will set it to
precise correctly.
As such, also remove a big comment about forward precision propagation
in mark_reg_stack_read() and avoid unnecessarily setting precision to
true after reading from STACK_ZERO stack. Again, precision propagation
will correctly handle this, if that SCALAR_VALUE register will ever be
needed to be precise.
Reported-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Acked-by: Maxim Mikityanskiy <maxtram95@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231218173601.53047-1-andrii@kernel.org
This patch adds a comment to check_mem_size_reg -- a function whose
meaning is not very transparent. The function implicitly deals with two
registers connected by convention, which is not obvious.
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231210225149.67639-1-andreimatei1@gmail.com
The function are defined in the verifier.c file, but not called
elsewhere, so delete the unused function.
kernel/bpf/verifier.c:3448:20: warning: unused function 'bt_set_slot'
kernel/bpf/verifier.c:3453:20: warning: unused function 'bt_clear_slot'
kernel/bpf/verifier.c:3488:20: warning: unused function 'bt_is_slot_set'
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20231212005436.103829-1-yang.lee@linux.alibaba.com
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7714
Use the fact that we are passing subprog index around and have
a corresponding struct bpf_subprog_info in bpf_verifier_env for each
subprogram. We don't need to separately pass around a flag whether
subprog is exception callback or not, each relevant verifier function
can determine this using provided subprog index if we maintain
bpf_subprog_info properly.
Also move out exception callback-specific logic from
btf_prepare_func_args(), keeping it generic. We can enforce all these
restriction right before exception callback verification pass. We add
out parameter, arg_cnt, for now, but this will be unnecessary with
subsequent refactoring and will be removed.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231204233931.49758-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When verifier validates BPF_ST_MEM instruction that stores known
constant to stack (e.g., *(u64 *)(r10 - 8) = 123), it effectively spills
a fake register with a constant (but initially imprecise) value to
a stack slot. Because read-side logic treats it as a proper register
fill from stack slot, we need to mark such stack slot initialization as
INSN_F_STACK_ACCESS instruction to stop precision backtracking from
missing it.
Fixes: 41f6f64e69 ("bpf: support non-r10 register spill/fill to/from stack in precision tracking")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20231209010958.66758-1-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Push the rounding up of stack offsets into the function responsible for
growing the stack, rather than relying on all the callers to do it.
Uncertainty about whether the callers did it or not tripped up people in
a previous review.
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/bpf/20231208032519.260451-4-andreimatei1@gmail.com
Privileged programs are supposed to be able to read uninitialized stack
memory (ever since 6715df8d5) but, before this patch, these accesses
were permitted inconsistently. In particular, accesses were permitted
above state->allocated_stack, but not below it. In other words, if the
stack was already "large enough", the access was permitted, but
otherwise the access was rejected instead of being allowed to "grow the
stack". This undesired rejection was happening in two places:
- in check_stack_slot_within_bounds()
- in check_stack_range_initialized()
This patch arranges for these accesses to be permitted. A bunch of tests
that were relying on the old rejection had to change; all of them were
changed to add also run unprivileged, in which case the old behavior
persists. One tests couldn't be updated - global_func16 - because it
can't run unprivileged for other reasons.
This patch also fixes the tracking of the stack size for variable-offset
reads. This second fix is bundled in the same commit as the first one
because they're inter-related. Before this patch, writes to the stack
using registers containing a variable offset (as opposed to registers
with fixed, known values) were not properly contributing to the
function's needed stack size. As a result, it was possible for a program
to verify, but then to attempt to read out-of-bounds data at runtime
because a too small stack had been allocated for it.
Each function tracks the size of the stack it needs in
bpf_subprog_info.stack_depth, which is maintained by
update_stack_depth(). For regular memory accesses, check_mem_access()
was calling update_state_depth() but it was passing in only the fixed
part of the offset register, ignoring the variable offset. This was
incorrect; the minimum possible value of that register should be used
instead.
This tracking is now fixed by centralizing the tracking of stack size in
grow_stack_state(), and by lifting the calls to grow_stack_state() to
check_stack_access_within_bounds() as suggested by Andrii. The code is
now simpler and more convincingly tracks the correct maximum stack size.
check_stack_range_initialized() can now rely on enough stack having been
allocated for the access; this helps with the fix for the first issue.
A few tests were changed to also check the stack depth computation. The
one that fails without this patch is verifier_var_off:stack_write_priv_vs_unpriv.
Fixes: 01f810ace9 ("bpf: Allow variable-offset stack access")
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231208032519.260451-3-andreimatei1@gmail.com
Closes: https://lore.kernel.org/bpf/CABWLsev9g8UP_c3a=1qbuZUi20tGoUXoU07FPf-5FLvhOKOY+Q@mail.gmail.com/
This patch promotes the arithmetic around checking stack bounds to be
done in the 64-bit domain, instead of the current 32bit. The arithmetic
implies adding together a 64-bit register with a int offset. The
register was checked to be below 1<<29 when it was variable, but not
when it was fixed. The offset either comes from an instruction (in which
case it is 16 bit), from another register (in which case the caller
checked it to be below 1<<29 [1]), or from the size of an argument to a
kfunc (in which case it can be a u32 [2]). Between the register being
inconsistently checked to be below 1<<29, and the offset being up to an
u32, it appears that we were open to overflowing the `int`s which were
currently used for arithmetic.
[1] 815fb87b75/kernel/bpf/verifier.c (L7494-L7498)
[2] 815fb87b75/kernel/bpf/verifier.c (L11904)
Reported-by: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231207041150.229139-4-andreimatei1@gmail.com
This patch fixes a bug around the verification of possibly-zero-sized
stack accesses. When the access was done through a var-offset stack
pointer, check_stack_access_within_bounds was incorrectly computing the
maximum-offset of a zero-sized read to be the same as the register's min
offset. Instead, we have to take in account the register's maximum
possible value. The patch also simplifies how the max offset is checked;
the check is now simpler than for min offset.
The bug was allowing accesses to erroneously pass the
check_stack_access_within_bounds() checks, only to later crash in
check_stack_range_initialized() when all the possibly-affected stack
slots are iterated (this time with a correct max offset).
check_stack_range_initialized() is relying on
check_stack_access_within_bounds() for its accesses to the
stack-tracking vector to be within bounds; in the case of zero-sized
accesses, we were essentially only verifying that the lowest possible
slot was within bounds. We would crash when the max-offset of the stack
pointer was >= 0 (which shouldn't pass verification, and hopefully is
not something anyone's code attempts to do in practice).
Thanks Hao for reporting!
Fixes: 01f810ace9 ("bpf: Allow variable-offset stack access")
Reported-by: Hao Sun <sunhao.th@gmail.com>
Signed-off-by: Andrei Matei <andreimatei1@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20231207041150.229139-2-andreimatei1@gmail.com
Closes: https://lore.kernel.org/bpf/CACkBjsZGEUaRCHsmaX=h-efVogsRfK1FPxmkgb0Os_frnHiNdw@mail.gmail.com/
Remove remaining direct queries to perfmon_capable() and bpf_capable()
in BPF verifier logic and instead use BPF token (if available) to make
decisions about privileges.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231130185229.2688956-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Similar to special handling of STACK_ZERO, when reading 1/2/4 bytes from
stack from slot that has register spilled into it and that register has
a constant value zero, preserve that zero and mark spilled register as
precise for that. This makes spilled const zero register and STACK_ZERO
cases equivalent in their behavior.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of always forcing STACK_ZERO slots to STACK_MISC, preserve it in
situations where this is possible. E.g., when spilling register as
1/2/4-byte subslots on the stack, all the remaining bytes in the stack
slot do not automatically become unknown. If we knew they contained
zeroes, we can preserve those STACK_ZERO markers.
Add a helper mark_stack_slot_misc(), similar to scrub_spilled_slot(),
but that doesn't overwrite either STACK_INVALID nor STACK_ZERO. Note
that we need to take into account possibility of being in unprivileged
mode, in which case STACK_INVALID is forced to STACK_MISC for correctness,
as treating STACK_INVALID as equivalent STACK_MISC is only enabled in
privileged mode.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When register is spilled onto a stack as a 1/2/4-byte register, we set
slot_type[BPF_REG_SIZE - 1] (plus potentially few more below it,
depending on actual spill size). So to check if some stack slot has
spilled register we need to consult slot_type[7], not slot_type[0].
To avoid the need to remember and double-check this in the future, just
use is_spilled_reg() helper.
Fixes: 27113c59b6 ("bpf: Check the other end of slot_type for STACK_SPILL")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use instruction (jump) history to record instructions that performed
register spill/fill to/from stack, regardless if this was done through
read-only r10 register, or any other register after copying r10 into it
*and* potentially adjusting offset.
To make this work reliably, we push extra per-instruction flags into
instruction history, encoding stack slot index (spi) and stack frame
number in extra 10 bit flags we take away from prev_idx in instruction
history. We don't touch idx field for maximum performance, as it's
checked most frequently during backtracking.
This change removes basically the last remaining practical limitation of
precision backtracking logic in BPF verifier. It fixes known
deficiencies, but also opens up new opportunities to reduce number of
verified states, explored in the subsequent patches.
There are only three differences in selftests' BPF object files
according to veristat, all in the positive direction (less states).
File Program Insns (A) Insns (B) Insns (DIFF) States (A) States (B) States (DIFF)
-------------------------------------- ------------- --------- --------- ------------- ---------- ---------- -------------
test_cls_redirect_dynptr.bpf.linked3.o cls_redirect 2987 2864 -123 (-4.12%) 240 231 -9 (-3.75%)
xdp_synproxy_kern.bpf.linked3.o syncookie_tc 82848 82661 -187 (-0.23%) 5107 5073 -34 (-0.67%)
xdp_synproxy_kern.bpf.linked3.o syncookie_xdp 85116 84964 -152 (-0.18%) 5162 5130 -32 (-0.62%)
Note, I avoided renaming jmp_history to more generic insn_hist to
minimize number of lines changed and potential merge conflicts between
bpf and bpf-next trees.
Notice also cur_hist_entry pointer reset to NULL at the beginning of
instruction verification loop. This pointer avoids the problem of
relying on last jump history entry's insn_idx to determine whether we
already have entry for current instruction or not. It can happen that we
added jump history entry because current instruction is_jmp_point(), but
also we need to add instruction flags for stack access. In this case, we
don't want to entries, so we need to reuse last added entry, if it is
present.
Relying on insn_idx comparison has the same ambiguity problem as the one
that was fixed recently in [0], so we avoid that.
[0] https://patchwork.kernel.org/project/netdevbpf/patch/20231110002638.4168352-3-andrii@kernel.org/
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Reported-by: Tao Lyu <tao.lyu@epfl.ch>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231205184248.1502704-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
When removing the inner map from the outer map, the inner map will be
freed after one RCU grace period and one RCU tasks trace grace
period, so it is certain that the bpf program, which may access the
inner map, has exited before the inner map is freed.
However there is no need to wait for one RCU tasks trace grace period if
the outer map is only accessed by non-sleepable program. So adding
sleepable_refcnt in bpf_map and increasing sleepable_refcnt when adding
the outer map into env->used_maps for sleepable program. Although the
max number of bpf program is INT_MAX - 1, the number of bpf programs
which are being loaded may be greater than INT_MAX, so using atomic64_t
instead of atomic_t for sleepable_refcnt. When removing the inner map
from the outer map, using sleepable_refcnt to decide whether or not a
RCU tasks trace grace period is needed before freeing the inner map.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231204140425.1480317-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Given we enforce a valid range for program and async callback return
value, we must mark R0 as precise to avoid incorrect state pruning.
Fixes: b5dc0163d8 ("bpf: precise scalar_value tracking")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-9-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Use common logic to verify program return values and async callback
return values. This allows to avoid duplication of any extra steps
necessary, like precision marking, which will be added in the next
patch.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-8-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Similarly to subprog/callback logic, enforce return value of BPF program
using more precise smin/smax range.
We need to adjust a bunch of tests due to a changed format of an error
message.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-7-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Instead of relying on potentially imprecise tnum representation of
expected return value range for callbacks and subprogs, validate that
smin/smax range satisfy exact expected range of return values.
E.g., if callback would need to return [0, 2] range, tnum can't
represent this precisely and instead will allow [0, 3] range. By
checking smin/smax range, we can make sure that subprog/callback indeed
returns only valid [0, 2] range.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Given verifier checks actual value, r0 has to be precise, so we need to
propagate precision properly. r0 also has to be marked as read,
otherwise subsequent state comparisons will ignore such register as
unimportant and precision won't really help here.
Fixes: 69c087ba62 ("bpf: Add bpf_for_each_map_elem() helper")
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20231202175705.885270-4-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Slightly change BPF verifier logic around eagerness and order of global
subprog validation. Instead of going over every global subprog eagerly
and validating it before main (entry) BPF program is verified, turn it
around. Validate main program first, mark subprogs that were called from
main program for later verification, but otherwise assume it is valid.
Afterwards, go over marked global subprogs and validate those,
potentially marking some more global functions as being called. Continue
this process until all (transitively) callable global subprogs are
validated. It's a BFS traversal at its heart and will always converge.
This is an important change because it allows to feature-gate some
subprograms that might not be verifiable on some older kernel, depending
on supported set of features.
E.g., at some point, global functions were allowed to accept a pointer
to memory, which size is identified by user-provided type.
Unfortunately, older kernels don't support this feature. With BPF CO-RE
approach, the natural way would be to still compile BPF object file once
and guard calls to this global subprog with some CO-RE check or using
.rodata variables. That's what people do to guard usage of new helpers
or kfuncs, and any other new BPF-side feature that might be missing on
old kernels.
That's currently impossible to do with global subprogs, unfortunately,
because they are eagerly and unconditionally validated. This patch set
aims to change this, so that in the future when global funcs gain new
features, those can be guarded using BPF CO-RE techniques in the same
fashion as any other new kernel feature.
Two selftests had to be adjusted in sync with these changes.
test_global_func12 relied on eager global subprog validation failing
before main program failure is detected (unknown return value). Fix by
making sure that main program is always valid.
verifier_subprog_precision's parent_stack_slot_precise subtest relied on
verifier checkpointing heuristic to do a checkpoint at instruction #5,
but that's no longer true because we don't have enough jumps validated
before reaching insn #5 due to global subprogs being validated later.
Other than that, no changes, as one would expect.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231124035937.403208-3-andrii@kernel.org
We have the name, instead of emitting just func#N to identify global
subprog, augment verifier log messages with actual function name to make
it more user-friendly.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20231124035937.403208-2-andrii@kernel.org
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Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Daniel Borkmann says:
====================
pull-request: bpf-next 2023-11-21
We've added 85 non-merge commits during the last 12 day(s) which contain
a total of 63 files changed, 4464 insertions(+), 1484 deletions(-).
The main changes are:
1) Huge batch of verifier changes to improve BPF register bounds logic
and range support along with a large test suite, and verifier log
improvements, all from Andrii Nakryiko.
2) Add a new kfunc which acquires the associated cgroup of a task within
a specific cgroup v1 hierarchy where the latter is identified by its id,
from Yafang Shao.
3) Extend verifier to allow bpf_refcount_acquire() of a map value field
obtained via direct load which is a use-case needed in sched_ext,
from Dave Marchevsky.
4) Fix bpf_get_task_stack() helper to add the correct crosstask check
for the get_perf_callchain(), from Jordan Rome.
5) Fix BPF task_iter internals where lockless usage of next_thread()
was wrong. The rework also simplifies the code, from Oleg Nesterov.
6) Fix uninitialized tail padding via LIBBPF_OPTS_RESET, and another
fix for certain BPF UAPI structs to fix verifier failures seen
in bpf_dynptr usage, from Yonghong Song.
7) Add BPF selftest fixes for map_percpu_stats flakes due to per-CPU BPF
memory allocator not being able to allocate per-CPU pointer successfully,
from Hou Tao.
8) Add prep work around dynptr and string handling for kfuncs which
is later going to be used by file verification via BPF LSM and fsverity,
from Song Liu.
9) Improve BPF selftests to update multiple prog_tests to use ASSERT_*
macros, from Yuran Pereira.
10) Optimize LPM trie lookup to check prefixlen before walking the trie,
from Florian Lehner.
11) Consolidate virtio/9p configs from BPF selftests in config.vm file
given they are needed consistently across archs, from Manu Bretelle.
12) Small BPF verifier refactor to remove register_is_const(),
from Shung-Hsi Yu.
* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (85 commits)
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in vmlinux
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bpf_obj_id
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bind_perm
selftests/bpf: Replaces the usage of CHECK calls for ASSERTs in bpf_tcp_ca
selftests/bpf: reduce verboseness of reg_bounds selftest logs
bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos)
bpf: bpf_iter_task_next: use __next_thread() rather than next_thread()
bpf: task_group_seq_get_next: use __next_thread() rather than next_thread()
bpf: emit frameno for PTR_TO_STACK regs if it differs from current one
bpf: smarter verifier log number printing logic
bpf: omit default off=0 and imm=0 in register state log
bpf: emit map name in register state if applicable and available
bpf: print spilled register state in stack slot
bpf: extract register state printing
bpf: move verifier state printing code to kernel/bpf/log.c
bpf: move verbose_linfo() into kernel/bpf/log.c
bpf: rename BPF_F_TEST_SANITY_STRICT to BPF_F_TEST_REG_INVARIANTS
bpf: Remove test for MOVSX32 with offset=32
selftests/bpf: add iter test requiring range x range logic
veristat: add ability to set BPF_F_TEST_SANITY_STRICT flag with -r flag
...
====================
Link: https://lore.kernel.org/r/20231122000500.28126-1-daniel@iogearbox.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
