From: bot+bpf-ci@kernel.org
To: utilityemal77@gmail.com,ast@kernel.org,daniel@iogearbox.net,andrii@kernel.org,kpsingh@kernel.org,matt@bobrowski.net,paul@paul-moore.com,mic@digikod.net,viro@zeniv.linux.org.uk,brauner@kernel.org,kees@kernel.org
Cc: casey@schaufler-ca.com,gnoack@google.com,jack@suse.cz,song@kernel.org,yonghong.song@linux.dev,martin.lau@linux.dev,eddyz87@gmail.com,memxor@gmail.com,jolsa@kernel.org,m@maowtm.org,bpf@vger.kernel.org,linux-security-module@vger.kernel.org,linux-kernel@vger.kernel.org,utilityemal77@gmail.com,ast@kernel.org,andrii@kernel.org,daniel@iogearbox.net,martin.lau@kernel.org,eddyz87@gmail.com,yonghong.song@linux.dev,mason@kernel.org,ihor.solodrai@linux.dev
Subject: Re: [PATCH bpf-next v3 06/15] lsm: Add the bpf_lsm_policy_acquire kfunc
Date: Wed, 9 Sep 2026 20:30:00 +0000 (UTC) [thread overview]
Message-ID: <023aac007780af00c0060b296fe83c373e580c42836e08807ca1f61ce82ca009@mail.kernel.org> (raw)
In-Reply-To: <20260909193719.518517-7-utilityemal77@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2066 bytes --]
> diff --git a/security/bpf_lsm_kfuncs.c b/security/bpf_lsm_kfuncs.c
> index 988dcd6f4dd9..43a4bf57fd31 100644
> --- a/security/bpf_lsm_kfuncs.c
> +++ b/security/bpf_lsm_kfuncs.c
> @@ -14,6 +14,36 @@
>
> __bpf_kfunc_start_defs();
>
> +/**
> + * bpf_lsm_policy_acquire - Acquire a reference on a shared policy object
> + * @object: RCU-protected pointer to a policy object, e.g. loaded from
> + * a map kptr field under bpf_rcu_read_lock()
> + *
> + * Acquire a reference of its own on a policy object the program does
> + * not own, so that any number of concurrent program executions can
> + * use the object shared through one map kptr field, without emptying
> + * it as bpf_kptr_xchg() would. The returned reference stays valid
> + * after bpf_rcu_read_unlock() and must be released with
> + * bpf_lsm_policy_release().
> + *
> + * Return: A referenced policy object, or NULL if the object's
> + * reference count concurrently dropped to zero.
> + */
This isn't a bug, but would it be worth spelling out the other NULL
cases here -- no enabled LSM owning @object->lsmid, or the owning LSM's
get hook failing -- the way bpf_lsm_policy_from_fd()'s Return: section
does just below?
The current text names one of the three ways the kfunc yields NULL. The
body also returns NULL when no enabled LSM's policy_object_get static
call matches @object->lsmid, and when the owning LSM's hook fails for a
reason other than a dead refcount.
> +__bpf_kfunc struct lsm_policy_object *
> +bpf_lsm_policy_acquire(struct lsm_policy_object *object)
> +{
> + struct lsm_static_call *scall;
> +
> + lsm_for_each_hook(scall, policy_object_get) {
> + if (scall->hl->lsmid->id != object->lsmid)
> + continue;
> + if (scall->hl->hook.policy_object_get(object))
> + return NULL;
> + return object;
> + }
> + return NULL;
> +}
---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
CI run summary: https://github.com/kernel-patches/bpf/actions/runs/34398515657
next prev parent reply other threads:[~2026-09-09 20:30 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-09 19:37 [PATCH bpf-next v3 00/15] BPF interface for applying Landlock rulesets Justin Suess
2026-09-09 19:37 ` [PATCH bpf-next v3 01/15] lsm: Add the LSM policy object lifetime hooks Justin Suess
2026-09-09 19:37 ` [PATCH bpf-next v3 02/15] lsm: Add the bprm_apply_policy_object LSM hook Justin Suess
2026-09-09 19:37 ` [PATCH bpf-next v3 03/15] lsm: Move the lsm_for_each_hook() macro to security/lsm.h Justin Suess
2026-09-09 19:37 ` [PATCH bpf-next v3 04/15] lsm: Add the bpf_lsm_policy_release kfunc and policy object destructor Justin Suess
2026-09-09 20:29 ` bot+bpf-ci
2026-09-09 21:34 ` Paul Moore
2026-09-09 22:20 ` Justin Suess
2026-09-09 23:08 ` Paul Moore
2026-09-12 3:37 ` Alexei Starovoitov
2026-09-12 5:26 ` Justin Suess
2026-09-12 19:33 ` Alexei Starovoitov
2026-09-13 19:41 ` Paul Moore
2026-09-09 19:37 ` [PATCH bpf-next v3 05/15] lsm: Add the bpf_lsm_policy_from_fd kfunc Justin Suess
2026-09-09 20:46 ` bot+bpf-ci
2026-09-09 19:37 ` [PATCH bpf-next v3 06/15] lsm: Add the bpf_lsm_policy_acquire kfunc Justin Suess
2026-09-09 20:30 ` bot+bpf-ci [this message]
2026-09-09 19:37 ` [PATCH bpf-next v3 07/15] lsm: Add the bpf_lsm_policy_apply_bprm kfunc Justin Suess
[not found] ` <20260909195500.DA3E31F000FF@smtp.kernel.org>
2026-09-09 20:20 ` Justin Suess
2026-09-12 3:38 ` Alexei Starovoitov
2026-09-12 5:39 ` Justin Suess
2026-09-09 19:37 ` [PATCH bpf-next v3 08/15] lsm: Document the LSM policy object interface Justin Suess
2026-09-09 19:37 ` [PATCH bpf-next v3 09/15] selftests/bpf: Add tests for the LSM policy object kfuncs Justin Suess
2026-09-09 20:30 ` bot+bpf-ci
2026-09-09 19:37 ` [PATCH bpf-next v3 10/15] landlock: Expose the ruleset fd lookup to the rest of Landlock Justin Suess
2026-09-09 19:37 ` [PATCH bpf-next v3 11/15] landlock: Factor the credential restriction out of landlock_restrict_self() Justin Suess
2026-09-09 20:29 ` bot+bpf-ci
2026-09-09 19:37 ` [PATCH bpf-next v3 12/15] landlock: Free rulesets after an RCU grace period Justin Suess
2026-09-09 20:46 ` bot+bpf-ci
2026-09-09 19:37 ` [PATCH bpf-next v3 13/15] landlock: Implement the LSM policy object hooks Justin Suess
2026-09-09 20:46 ` bot+bpf-ci
2026-09-09 19:37 ` [PATCH bpf-next v3 14/15] selftests/bpf: Test the LSM policy object kfuncs with Landlock Justin Suess
2026-09-09 20:46 ` bot+bpf-ci
2026-09-09 19:37 ` [PATCH bpf-next v3 15/15] landlock: Document the BPF policy interface Justin Suess
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