[PATCH] landlock: Annotate struct landlock_rule with __counted_by

From: Kees Cook <keescook@chromium.org>
To: "Mickaël Salaün" <mic@digikod.net>
Cc: Kees Cook <keescook@chromium.org>,
	Paul Moore <paul@paul-moore.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	linux-security-module@vger.kernel.org,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Tom Rix <trix@redhat.com>,
	linux-kernel@vger.kernel.org, llvm@lists.linux.dev,
	linux-hardening@vger.kernel.org
Subject: [PATCH] landlock: Annotate struct landlock_rule with __counted_by
Date: Thu, 17 Aug 2023 14:03:01 -0700	[thread overview]
Message-ID: <20230817210257.never.920-kees@kernel.org> (raw)

Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct landlock_rule.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: "Mickaël Salaün" <mic@digikod.net>
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 security/landlock/ruleset.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
index d43231b783e4..55b1df8f66a8 100644
--- a/security/landlock/ruleset.h
+++ b/security/landlock/ruleset.h
@@ -67,7 +67,7 @@ struct landlock_rule {
 	 * @layers: Stack of layers, from the latest to the newest, implemented
 	 * as a flexible array member (FAM).
 	 */
-	struct landlock_layer layers[];
+	struct landlock_layer layers[] __counted_by(num_layers);
 };
 
 /**
-- 
2.34.1

