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

Thanks! Applied to my next tree. Feel free to carry it yourself if you
prefer.

On Thu, Aug 17, 2023 at 02:03:01PM -0700, Kees Cook wrote:
> 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
> 

On 8/17/23 15:03, Kees Cook wrote:
> 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>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

> ---
>   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);
>   };
>   
>   /**

On Thu, Aug 17, 2023 at 2:03 PM Kees Cook <keescook@chromium.org> wrote:
>
> 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>
Reviewed-by: Justin Stitt <justinstitt@google.com>

> ---
>  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
>