linux-kernel - Re: [RFC] c/r: prctl: Add ability to set new mm_struct::exe

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Date:	Thu, 8 Mar 2012 12:02:50 -0800
From:	Andy Lutomirski <luto@...capital.net>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>
Cc:	Kees Cook <keescook@...omium.org>, Oleg Nesterov <oleg@...hat.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Pavel Emelyanov <xemul@...allels.com>,
	Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Will Drewry <wad@...omium.org>
Subject: Re: [RFC] c/r: prctl: Add ability to set new mm_struct::exe_file v3

On Thu, Mar 8, 2012 at 11:40 AM, Cyrill Gorcunov <gorcunov@...nvz.org> wrote:
> On Thu, Mar 08, 2012 at 11:31:58AM -0800, Kees Cook wrote:
> ...
>> > +       err = -EACCES;
>> > +       if (!S_ISREG(dentry->d_inode->i_mode)   ||
>> > +           exe_file->f_path.mnt->mnt_flags & MNT_NOEXEC)
>> > +               goto exit;
>>
>> I'm starting to notice that this pattern (testing ISREG and
>> MNT_NOEXEC) is getting repeated a few times in the kernel, and at
>> least the no-new-privs patch (not yet in -mm but hopefully soon given
>> the seccomp_filter work) updates this pattern everywhere. Perhaps this
>> should be extracted into a helper first, and then this patch can call
>> that helper here? (And then nnp can just update the single helper.)
>>
>
> I can do that if Andrew agree.

I'm a bit lost.  nnp updates the MNT_NOSUID checks, not the MNT_NOEXEC
checks.  (And the effects of the two flags is different in selinux for
historical reasons.)  I'm sure I'm missing something.

--Andy

>
>        Cyrill
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