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bpf: Remove unnecessary CAP_MAC_ADMIN check 

While well intentioned, checking CAP_MAC_ADMIN for attaching
BPF_MODIFY_RETURN tracing programs to "security_" functions is not
necessary as tracing BPF programs already require CAP_SYS_ADMIN.

Fixes: 6ba43b761c ("bpf: Attachment verification for BPF_MODIFY_RETURN")
Signed-off-by: KP Singh <kpsingh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200305204955.31123-1-kpsingh@chromium.org
This commit is contained in:
KP Singh 2020-03-05 21:49:55 +01:00 committed by Alexei Starovoitov
parent dad737c926
commit 69191754ff
1 changed files with 3 additions and 10 deletions
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13
kernel/bpf/verifier.c
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@ -9808,20 +9808,13 @@ static int check_attach_modify_return(struct bpf_verifier_env *env)
struct bpf_prog *prog = env->prog;
unsigned long addr = (unsigned long) prog->aux->trampoline->func.addr;
if (within_error_injection_list(addr))
return 0;
/* This is expected to be cleaned up in the future with the KRSI effort
* introducing the LSM_HOOK macro for cleaning up lsm_hooks.h.
*/
if (!strncmp(SECURITY_PREFIX, prog->aux->attach_func_name,
sizeof(SECURITY_PREFIX) - 1)) {
if (!capable(CAP_MAC_ADMIN))
return -EPERM;
if (within_error_injection_list(addr) ||
!strncmp(SECURITY_PREFIX, prog->aux->attach_func_name,
sizeof(SECURITY_PREFIX) - 1))
return 0;
}
verbose(env, "fmod_ret attach_btf_id %u (%s) is not modifiable\n",
prog->aux->attach_btf_id, prog->aux->attach_func_name);