linux-kernel - Re: [PATCH AUTOSEL 5.10 7/8] exec: Distinguish in_execve from in

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Date: Sun, 18 Feb 2024 20:12:56 +0100
From: Pavel Machek <pavel@...x.de>
To: Sasha Levin <sashal@...nel.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Kees Cook <keescook@...omium.org>,
	Kentaro Takeda <takedakn@...data.co.jp>,
	Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	Eric Biederman <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, mingo@...hat.com,
	peterz@...radead.org, juri.lelli@...hat.com,
	vincent.guittot@...aro.org, surenb@...gle.com,
	michael.christie@...cle.com, mst@...hat.com, mjguzik@...il.com,
	npiggin@...il.com, zhangpeng.00@...edance.com, hca@...ux.ibm.com
Subject: Re: [PATCH AUTOSEL 5.10 7/8] exec: Distinguish in_execve from in_exec

Hi!

> From: Kees Cook <keescook@...omium.org>
> 
> [ Upstream commit 90383cc07895183c75a0db2460301c2ffd912359 ]
> 
> Just to help distinguish the fs->in_exec flag from the current->in_execve
> flag, add comments in check_unsafe_exec() and copy_fs() for more
> context. Also note that in_execve is only used by TOMOYO now.

These are just a whitespace changes, we should not need them.

Best regards,
								Pavel

> +++ b/fs/exec.c
> @@ -1565,6 +1565,7 @@ static void check_unsafe_exec(struct linux_binprm *bprm)
>  	}
>  	rcu_read_unlock();
>  
> +	/* "users" and "in_exec" locked for copy_fs() */
>  	if (p->fs->users > n_fs)
>  		bprm->unsafe |= LSM_UNSAFE_SHARE;
>  	else
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index aa015416c569..65cfe85de8d5 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -806,7 +806,7 @@ struct task_struct {
>  	 */
>  	unsigned			sched_remote_wakeup:1;
>  
> -	/* Bit to tell LSMs we're in execve(): */
> +	/* Bit to tell TOMOYO we're in execve(): */
>  	unsigned			in_execve:1;
>  	unsigned			in_iowait:1;
>  #ifndef TIF_RESTORE_SIGMASK
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 633b0af1d1a7..906dbaf25058 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1452,6 +1452,7 @@ static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
>  	if (clone_flags & CLONE_FS) {
>  		/* tsk->fs is already what we want */
>  		spin_lock(&fs->lock);
> +		/* "users" and "in_exec" locked for check_unsafe_exec() */
>  		if (fs->in_exec) {
>  			spin_unlock(&fs->lock);
>  			return -EAGAIN;

-- 
DENX Software Engineering GmbH,        Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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