bpf: Remove unnecessary CAP_MAC_ADMIN check (69191754) · Commits · 戴 / test

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: ("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

kernel/bpf/verifier.c

+3 −10

Original line number	Diff line number	Diff line
		@@ -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);

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