linux-kernel - Re: [PATCH 1/2] CRED: Rename cred_exec_mutex to reflect that it's a guard against ptrace

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Date:	Sat, 9 May 2009 20:59:06 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	David Howells <dhowells@...hat.com>
Cc:	roland@...hat.com, jmorris@...ei.org, chrisw@...s-sol.org,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, eparis@...hat.com,
	sds@...ho.nsa.gov, Ingo Molnar <mingo@...e.hu>
Subject: Re: [PATCH 1/2] CRED: Rename cred_exec_mutex to reflect that it's
	a guard against ptrace

Sorry for delay,

On 05/08, David Howells wrote:
>
> @@ -185,10 +185,11 @@ int ptrace_attach(struct task_struct *task)
>  	if (same_thread_group(task, current))
>  		goto out;
>
> -	/* Protect exec's credential calculations against our interference;
> -	 * SUID, SGID and LSM creds get determined differently under ptrace.
> +	/* Protect the target's credential calculations against our
> +	 * interference; SUID, SGID and LSM creds get determined differently
> +	 * under ptrace.
>  	 */
> -	retval = mutex_lock_interruptible(&task->cred_exec_mutex);
> +	retval = mutex_lock_interruptible(&task->cred_guard_mutex);
>  	if (retval  < 0)
>  		goto out;
>
> @@ -232,7 +233,7 @@ repeat:
>  bad:
>  	write_unlock_irqrestore(&tasklist_lock, flags);
>  	task_unlock(task);
> -	mutex_unlock(&task->cred_exec_mutex);
> +	mutex_unlock(&task->cred_guard_mutex);

This rename is obviously fine, but conflicts with
ptrace-do-not-use-task_lock-for-attach.patch in -mm tree:

-bad:
-       write_unlock_irqrestore(&tasklist_lock, flags);
-       task_unlock(task);
+unlock_tasklist:
+       write_unlock_irq(&tasklist_lock);
+unlock_creds:
        mutex_unlock(&task->cred_exec_mutex);
 out:
        return retval;


Hmm. Ingo's "rename ptrace_may_access => ptrace_access_check" conflicts
with my patch too.


Andrew, Roland, I guess I should re-send
	
	ptrace-ptrace_attach-check-pf_kthread-exit_state-instead-of-mm.patch
	ptrace-cleanup-check-set-of-pt_ptraced-during-attach.patch
	ptrace-do-not-use-task_lock-for-attach.patch

patches?

Oleg.

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