mirror of
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2025-09-04 20:19:47 +08:00
082f1db02c
Certain bpf syscall subcommands are available for usage from both userspace and the kernel. LSM modules or eBPF gatekeeper programs may need to take a different course of action depending on whether or not a BPF syscall originated from the kernel or userspace. Additionally, some of the bpf_attr struct fields contain pointers to arbitrary memory. Currently the functionality to determine whether or not a pointer refers to kernel memory or userspace memory is exposed to the bpf verifier, but that information is missing from various LSM hooks. Here we augment the LSM hooks to provide this data, by simply passing a boolean flag indicating whether or not the call originated in the kernel, in any hook that contains a bpf_attr struct that corresponds to a subcommand that may be called from the kernel. Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com> Acked-by: Song Liu <song@kernel.org> Acked-by: Paul Moore <paul@paul-moore.com> Link: https://lore.kernel.org/r/20250310221737.821889-2-bboscaccy@linux.microsoft.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
47 lines
956 B
C
47 lines
956 B
C
// SPDX-License-Identifier: GPL-2.0
|
|
|
|
/*
|
|
* Copyright (C) 2022 Huawei Technologies Duesseldorf GmbH
|
|
*
|
|
* Author: Roberto Sassu <roberto.sassu@huawei.com>
|
|
*/
|
|
|
|
#include "vmlinux.h"
|
|
#include <errno.h>
|
|
#include <bpf/bpf_helpers.h>
|
|
#include <bpf/bpf_tracing.h>
|
|
|
|
char _license[] SEC("license") = "GPL";
|
|
|
|
__u32 monitored_pid;
|
|
__u32 key_serial;
|
|
__u32 key_id;
|
|
__u64 flags;
|
|
|
|
extern struct bpf_key *bpf_lookup_user_key(__u32 serial, __u64 flags) __ksym;
|
|
extern struct bpf_key *bpf_lookup_system_key(__u64 id) __ksym;
|
|
extern void bpf_key_put(struct bpf_key *key) __ksym;
|
|
|
|
SEC("lsm.s/bpf")
|
|
int BPF_PROG(bpf, int cmd, union bpf_attr *attr, unsigned int size, bool kernel)
|
|
{
|
|
struct bpf_key *bkey;
|
|
__u32 pid;
|
|
|
|
pid = bpf_get_current_pid_tgid() >> 32;
|
|
if (pid != monitored_pid)
|
|
return 0;
|
|
|
|
if (key_serial)
|
|
bkey = bpf_lookup_user_key(key_serial, flags);
|
|
else
|
|
bkey = bpf_lookup_system_key(key_id);
|
|
|
|
if (!bkey)
|
|
return -ENOENT;
|
|
|
|
bpf_key_put(bkey);
|
|
|
|
return 0;
|
|
}
|