netdev - [PATCH bpf-next v4 11/20] bpf, lsm: Add disabled BPF LSM hook list

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Message-Id: <20240711111908.3817636-12-xukuohai@huaweicloud.com>
Date: Thu, 11 Jul 2024 19:18:59 +0800
From: Xu Kuohai <xukuohai@...weicloud.com>
To: bpf@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	linux-kselftest@...r.kernel.org,
	linux-integrity@...r.kernel.org,
	apparmor@...ts.ubuntu.com,
	selinux@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>,
	Andrii Nakryiko <andrii@...nel.org>,
	Daniel Borkmann <daniel@...earbox.net>,
	Martin KaFai Lau <martin.lau@...ux.dev>,
	Eduard Zingerman <eddyz87@...il.com>,
	Song Liu <song@...nel.org>,
	Yonghong Song <yonghong.song@...ux.dev>,
	John Fastabend <john.fastabend@...il.com>,
	KP Singh <kpsingh@...nel.org>,
	Stanislav Fomichev <sdf@...gle.com>,
	Hao Luo <haoluo@...gle.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Matt Bobrowski <mattbobrowski@...gle.com>,
	Brendan Jackman <jackmanb@...omium.org>,
	Paul Moore <paul@...l-moore.com>,
	James Morris <jmorris@...ei.org>,
	"Serge E . Hallyn" <serge@...lyn.com>,
	Khadija Kamran <kamrankhadijadj@...il.com>,
	Casey Schaufler <casey@...aufler-ca.com>,
	Ondrej Mosnacek <omosnace@...hat.com>,
	Kees Cook <keescook@...omium.org>,
	John Johansen <john.johansen@...onical.com>,
	Lukas Bulwahn <lukas.bulwahn@...il.com>,
	Roberto Sassu <roberto.sassu@...wei.com>,
	Shung-Hsi Yu <shung-hsi.yu@...e.com>,
	Edward Cree <ecree.xilinx@...il.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Trond Myklebust <trond.myklebust@...merspace.com>,
	Anna Schumaker <anna@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Stephen Smalley <stephen.smalley.work@...il.com>
Subject: [PATCH bpf-next v4 11/20] bpf, lsm: Add disabled BPF LSM hook list

From: Xu Kuohai <xukuohai@...wei.com>

Add a disabled hooks list for BPF LSM. progs being attached to the
listed hooks will be rejected by the verifier.

Suggested-by: KP Singh <kpsingh@...nel.org>
Signed-off-by: Xu Kuohai <xukuohai@...wei.com>
---
 kernel/bpf/bpf_lsm.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c
index 08a338e1f231..e5feb6560fe6 100644
--- a/kernel/bpf/bpf_lsm.c
+++ b/kernel/bpf/bpf_lsm.c
@@ -36,6 +36,12 @@ BTF_SET_START(bpf_lsm_hooks)
 #undef LSM_HOOK
 BTF_SET_END(bpf_lsm_hooks)
 
+BTF_SET_START(bpf_lsm_disabled_hooks)
+BTF_ID(func, bpf_lsm_getprocattr)
+BTF_ID(func, bpf_lsm_setprocattr)
+BTF_ID(func, bpf_lsm_ismaclabel)
+BTF_SET_END(bpf_lsm_disabled_hooks)
+
 /* List of LSM hooks that should operate on 'current' cgroup regardless
  * of function signature.
  */
@@ -97,15 +103,24 @@ void bpf_lsm_find_cgroup_shim(const struct bpf_prog *prog,
 int bpf_lsm_verify_prog(struct bpf_verifier_log *vlog,
 			const struct bpf_prog *prog)
 {
+	u32 btf_id = prog->aux->attach_btf_id;
+	const char *func_name = prog->aux->attach_func_name;
+
 	if (!prog->gpl_compatible) {
 		bpf_log(vlog,
 			"LSM programs must have a GPL compatible license\n");
 		return -EINVAL;
 	}
 
-	if (!btf_id_set_contains(&bpf_lsm_hooks, prog->aux->attach_btf_id)) {
+	if (btf_id_set_contains(&bpf_lsm_disabled_hooks, btf_id)) {
+		bpf_log(vlog, "attach_btf_id %u points to disabled hook %s\n",
+			btf_id, func_name);
+		return -EINVAL;
+	}
+
+	if (!btf_id_set_contains(&bpf_lsm_hooks, btf_id)) {
 		bpf_log(vlog, "attach_btf_id %u points to wrong type name %s\n",
-			prog->aux->attach_btf_id, prog->aux->attach_func_name);
+			btf_id, func_name);
 		return -EINVAL;
 	}
 
-- 
2.30.2