Since task->comm is guaranteed to be NUL-terminated, we can print it
directly without the need to copy it into a separate buffer. This
simplifies the code and avoids unnecessary operations.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
---
 security/yama/yama_lsm.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
index e1a5e13ea269..4bdfa51ea6fd 100644
--- a/security/yama/yama_lsm.c
+++ b/security/yama/yama_lsm.c
@@ -76,7 +76,6 @@ static void report_access(const char *access, struct task_struct *target,
 				struct task_struct *agent)
 {
 	struct access_report_info *info;
-	char agent_comm[sizeof(agent->comm)];
 
 	assert_spin_locked(&target->alloc_lock); /* for target->comm */
 
@@ -85,9 +84,8 @@ static void report_access(const char *access, struct task_struct *target,
 		 * Imagine angry ranting about procfs here.
 		 */
 		pr_notice_ratelimited(
-		    "ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n",
-		    access, target->comm, target->pid,
-		    get_task_comm(agent_comm, agent), agent->pid);
+		    "ptrace %s of \"%pTN\"[%d] was attempted by \"%pTN\"[%d]\n",
+		    access, target, target->pid, agent, agent->pid);
 		return;
 	}
 
-- 
2.43.5

On Thu, 12 Dec 2024 at 21:47, Yafang Shao <laoar.shao@gmail.com> wrote:
>
> Since task->comm is guaranteed to be NUL-terminated, we can print it
> directly without the need to copy it into a separate buffer.

So i think we should do the "without copying into a separate buffer"
part of this series, but I do think we should just accept "%s" and
"task->comm".

IOW - getting rid of get_task_comm() is good.

But the "%pTN" pointer format ends up being unnecessary.

          Linus

On Fri, Dec 13, 2024 at 01:46:08PM +0800, Yafang Shao wrote:
> Since task->comm is guaranteed to be NUL-terminated, we can print it
> directly without the need to copy it into a separate buffer. This
> simplifies the code and avoids unnecessary operations.
> 
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>

Looks good to me; thanks!

Acked-by: Kees Cook <kees@kernel.org>

-- 
Kees Cook

On Fri, Dec 13, 2024 at 12:47 AM Yafang Shao <laoar.shao@gmail.com> wrote:
>
> Since task->comm is guaranteed to be NUL-terminated, we can print it
> directly without the need to copy it into a separate buffer. This
> simplifies the code and avoids unnecessary operations.
>
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> Cc: Kees Cook <kees@kernel.org>
> Cc: Paul Moore <paul@paul-moore.com>
> Cc: James Morris <jmorris@namei.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> ---
>  security/yama/yama_lsm.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)

You need to wait for Kees' ACK, but this looks okay to me.

Reviewed-by: Paul Moore <paul@paul-moore.com>

> diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c
> index e1a5e13ea269..4bdfa51ea6fd 100644
> --- a/security/yama/yama_lsm.c
> +++ b/security/yama/yama_lsm.c
> @@ -76,7 +76,6 @@ static void report_access(const char *access, struct task_struct *target,
>                                 struct task_struct *agent)
>  {
>         struct access_report_info *info;
> -       char agent_comm[sizeof(agent->comm)];
>
>         assert_spin_locked(&target->alloc_lock); /* for target->comm */
>
> @@ -85,9 +84,8 @@ static void report_access(const char *access, struct task_struct *target,
>                  * Imagine angry ranting about procfs here.
>                  */
>                 pr_notice_ratelimited(
> -                   "ptrace %s of \"%s\"[%d] was attempted by \"%s\"[%d]\n",
> -                   access, target->comm, target->pid,
> -                   get_task_comm(agent_comm, agent), agent->pid);
> +                   "ptrace %s of \"%pTN\"[%d] was attempted by \"%pTN\"[%d]\n",
> +                   access, target, target->pid, agent, agent->pid);
>                 return;
>         }
>
> --
> 2.43.5

-- 
paul-moore.com