mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-09-04 20:19:47 +08:00
03b77e17ae
__kptr meant to store PTR_UNTRUSTED kernel pointers inside bpf maps. The concept felt useful, but didn't get much traction, since bpf_rdonly_cast() was added soon after and bpf programs received a simpler way to access PTR_UNTRUSTED kernel pointers without going through restrictive __kptr usage. Rename __kptr_ref -> __kptr and __kptr -> __kptr_untrusted to indicate its intended usage. The main goal of __kptr_untrusted was to read/write such pointers directly while bpf_kptr_xchg was a mechanism to access refcnted kernel pointers. The next patch will allow RCU protected __kptr access with direct read. At that point __kptr_untrusted will be deprecated. Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: David Vernet <void@manifault.com> Link: https://lore.kernel.org/bpf/20230303041446.3630-2-alexei.starovoitov@gmail.com
62 lines
1.2 KiB
C
62 lines
1.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/* Copyright (c) 2022 Meta Platforms, Inc. and affiliates. */
|
|
#include <vmlinux.h>
|
|
#include <bpf/bpf_tracing.h>
|
|
#include <bpf/bpf_helpers.h>
|
|
|
|
static struct prog_test_ref_kfunc __kptr *v;
|
|
long total_sum = -1;
|
|
|
|
extern struct prog_test_ref_kfunc *bpf_kfunc_call_test_acquire(unsigned long *sp) __ksym;
|
|
extern void bpf_kfunc_call_test_release(struct prog_test_ref_kfunc *p) __ksym;
|
|
|
|
SEC("tc")
|
|
int test_jit_probe_mem(struct __sk_buff *ctx)
|
|
{
|
|
struct prog_test_ref_kfunc *p;
|
|
unsigned long zero = 0, sum;
|
|
|
|
p = bpf_kfunc_call_test_acquire(&zero);
|
|
if (!p)
|
|
return 1;
|
|
|
|
p = bpf_kptr_xchg(&v, p);
|
|
if (p)
|
|
goto release_out;
|
|
|
|
/* Direct map value access of kptr, should be PTR_UNTRUSTED */
|
|
p = v;
|
|
if (!p)
|
|
return 1;
|
|
|
|
asm volatile (
|
|
"r9 = %[p];"
|
|
"%[sum] = 0;"
|
|
|
|
/* r8 = p->a */
|
|
"r8 = *(u32 *)(r9 + 0);"
|
|
"%[sum] += r8;"
|
|
|
|
/* r8 = p->b */
|
|
"r8 = *(u32 *)(r9 + 4);"
|
|
"%[sum] += r8;"
|
|
|
|
"r9 += 8;"
|
|
/* r9 = p->a */
|
|
"r9 = *(u32 *)(r9 - 8);"
|
|
"%[sum] += r9;"
|
|
|
|
: [sum] "=r"(sum)
|
|
: [p] "r"(p)
|
|
: "r8", "r9"
|
|
);
|
|
|
|
total_sum = sum;
|
|
return 0;
|
|
release_out:
|
|
bpf_kfunc_call_test_release(p);
|
|
return 1;
|
|
}
|
|
|
|
char _license[] SEC("license") = "GPL";
|