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From: pageexec@freemail.hu
To: Roland McGrath <roland@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
	Brad Spengler <spender@grsecurity.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, oss-security@lists.openwall.com,
	Solar Designer <solar@openwall.com>,
	Kees Cook <kees.cook@canonical.com>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Oleg Nesterov <oleg@redhat.com>,
	Neil Horman <nhorman@tuxdriver.com>,
	linux-fsdevel@vger.kernel.org, Eugene Teo <eugene@redhat.com>
Subject: Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size
Date: Tue, 14 Sep 2010 22:28:31 +0200	[thread overview]
Message-ID: <4C8FDAEF.17347.14CA1791@pageexec.freemail.hu> (raw)
In-Reply-To: <20100914185135.03DD6403E8@magilla.sf.frob.com>

On 14 Sep 2010 at 11:51, Roland McGrath wrote:

> > no it doesn't have to, similarly to how it doesn't have to hardcode
> > _SC_PAGESIZE either, AT_PAGESZ tells userland what it needs to know
> > and i think AT_ARGMAX could exist just as well.
> 
> I was referring to the ways available to userland heretofore.  Certainly,
> the kernel could add new ways and then userland could do different things
> (with new kernels).  
> 
> auxv in particular is not a mechanism that could fit for this.  The actual
> limit depends on rlimits of the calling process, and rlimits can change
> during the life of the program.

obviously an AT_ARGMAX computed at execve time would be based on the rlimits
as well and if later userland changed the rlimits, it'd be userland's problem,
not that of the kernel (or the kernel could refuse a change that would violate
its earlier promise).

>  auxv is only appropriate for things that
> are known at the time of the exec and won't change thereafter.

you mean stuff like AT_EUID et al.? ;)


WARNING: multiple messages have this Message-ID (diff)
From: pageexec-Y8qEzhMunLyT9ig0jae3mg@public.gmane.org
To: Roland McGrath <roland-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: KOSAKI Motohiro
	<kosaki.motohiro-+CUm20s59erQFUHtdCDX3A@public.gmane.org>,
	Brad Spengler <spender-JNS0hek0TMl4qEwOxq4T+Q@public.gmane.org>,
	Linus Torvalds
	<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	oss-security-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org,
	Solar Designer <solar-cxoSlKxDwOJWk0Htik3J/w@public.gmane.org>,
	Kees Cook <kees.cook-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>,
	Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>,
	Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Neil Horman <nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org>,
	linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Eugene Teo <eugene-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH 1/3] setup_arg_pages: diagnose excessive argument size
Date: Tue, 14 Sep 2010 22:28:31 +0200	[thread overview]
Message-ID: <4C8FDAEF.17347.14CA1791@pageexec.freemail.hu> (raw)
In-Reply-To: <20100914185135.03DD6403E8-nL1rrgvulkc2UH6IwYuUx0EOCMrvLtNR@public.gmane.org>

On 14 Sep 2010 at 11:51, Roland McGrath wrote:

> > no it doesn't have to, similarly to how it doesn't have to hardcode
> > _SC_PAGESIZE either, AT_PAGESZ tells userland what it needs to know
> > and i think AT_ARGMAX could exist just as well.
> 
> I was referring to the ways available to userland heretofore.  Certainly,
> the kernel could add new ways and then userland could do different things
> (with new kernels).  
> 
> auxv in particular is not a mechanism that could fit for this.  The actual
> limit depends on rlimits of the calling process, and rlimits can change
> during the life of the program.

obviously an AT_ARGMAX computed at execve time would be based on the rlimits
as well and if later userland changed the rlimits, it'd be userland's problem,
not that of the kernel (or the kernel could refuse a change that would violate
its earlier promise).

>  auxv is only appropriate for things that
> are known at the time of the exec and won't change thereafter.

you mean stuff like AT_EUID et al.? ;)

  reply	other threads:[~2010-09-14 20:30 UTC|newest]

Thread overview: 81+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-27 22:02 [PATCH] exec argument expansion can inappropriately trigger OOM-killer Kees Cook
2010-08-30  0:19 ` KOSAKI Motohiro
2010-08-30  0:56 ` Roland McGrath
2010-08-30  3:23   ` Solar Designer
2010-08-30  3:23     ` Solar Designer
2010-08-30 10:06     ` Roland McGrath
2010-08-30 19:48       ` Solar Designer
2010-08-31  0:40         ` Roland McGrath
2010-09-08  2:34       ` [PATCH 0/3] execve argument-copying fixes Roland McGrath
2010-09-08  2:34         ` Roland McGrath
2010-09-08  2:35         ` [PATCH 1/3] setup_arg_pages: diagnose excessive argument size Roland McGrath
2010-09-08  2:35           ` Roland McGrath
2010-09-08  8:29           ` pageexec
2010-09-08  8:29             ` pageexec
2010-09-10  8:59             ` Roland McGrath
2010-09-10  8:59               ` Roland McGrath
2010-09-11 13:30               ` pageexec
2010-09-11 13:30                 ` pageexec-Y8qEzhMunLyT9ig0jae3mg
2010-09-14 19:33                 ` Roland McGrath
2010-09-14 22:35                   ` pageexec
2010-09-14 22:35                     ` pageexec-Y8qEzhMunLyT9ig0jae3mg
2010-09-08 11:57           ` Brad Spengler
2010-09-08 11:57             ` Brad Spengler
2010-09-09  5:31             ` KOSAKI Motohiro
2010-09-09  5:31               ` KOSAKI Motohiro
2010-09-10  9:25               ` Roland McGrath
2010-09-10  9:25                 ` Roland McGrath
2010-09-10  9:43                 ` KOSAKI Motohiro
2010-09-11 13:39                 ` pageexec
2010-09-11 13:39                   ` pageexec-Y8qEzhMunLyT9ig0jae3mg
2010-09-14 18:51                   ` Roland McGrath
2010-09-14 18:51                     ` Roland McGrath
2010-09-14 20:28                     ` pageexec [this message]
2010-09-14 20:28                       ` pageexec-Y8qEzhMunLyT9ig0jae3mg
2010-09-14 21:16                       ` Roland McGrath
2010-09-14 21:16                         ` Roland McGrath
2010-09-14 22:27                         ` pageexec
2010-09-14 22:27                           ` pageexec-Y8qEzhMunLyT9ig0jae3mg
2010-09-14 23:04                           ` Roland McGrath
2010-09-14 23:04                             ` Roland McGrath
2010-09-15  9:27                             ` pageexec
2010-09-15  9:27                               ` pageexec-Y8qEzhMunLyT9ig0jae3mg
2010-09-10  9:18             ` Roland McGrath
2010-09-10  9:18               ` Roland McGrath
2010-09-08  2:36         ` [PATCH 2/3] execve: improve interactivity with large arguments Roland McGrath
2010-09-08  2:36           ` Roland McGrath
2010-09-08  2:37         ` [PATCH 3/3] execve: make responsive to SIGKILL " Roland McGrath
2010-09-08  2:37           ` Roland McGrath
2010-09-08  3:00         ` [PATCH 0/3] execve argument-copying fixes KOSAKI Motohiro
2010-09-08  3:00           ` KOSAKI Motohiro
2010-09-09  5:01         ` [PATCH 0/2] execve memory exhaust of " KOSAKI Motohiro
2010-09-09  5:01           ` KOSAKI Motohiro
2010-09-09  5:03           ` [PATCH 1/2] oom: don't ignore rss in nascent mm KOSAKI Motohiro
2010-09-09  5:03             ` KOSAKI Motohiro
2010-09-09 22:05             ` Oleg Nesterov
2010-09-09 22:05               ` Oleg Nesterov
2010-09-10  9:39               ` Roland McGrath
2010-09-10  9:39                 ` Roland McGrath
2010-09-10  9:57               ` [PATCH] move cred_guard_mutex from task_struct to signal_struct KOSAKI Motohiro
2010-09-10  9:57                 ` KOSAKI Motohiro
2010-09-10 17:24                 ` Oleg Nesterov
2010-09-10 17:24                   ` Oleg Nesterov
2010-09-16  5:51                   ` KOSAKI Motohiro
2010-09-16  5:51                     ` KOSAKI Motohiro
2010-09-09  5:04           ` [PATCH 2/2] execve: check the VM has enough memory at first KOSAKI Motohiro
2010-09-09  5:04             ` KOSAKI Motohiro
2010-09-10 15:06             ` Linus Torvalds
2010-09-10 15:06               ` Linus Torvalds
2010-09-14  1:52               ` KOSAKI Motohiro
2010-09-14  1:52                 ` KOSAKI Motohiro
2010-09-16  5:51                 ` KOSAKI Motohiro
2010-09-16  5:51                   ` KOSAKI Motohiro
2010-09-16 15:01                   ` Linus Torvalds
2010-09-16 15:01                     ` Linus Torvalds
2010-08-30 17:49     ` [PATCH] exec argument expansion can inappropriately trigger OOM-killer Solar Designer
2010-08-30 17:49       ` Solar Designer
2010-08-30 22:08       ` Brad Spengler
2010-08-30 22:08         ` Brad Spengler
2010-08-31 11:53         ` Solar Designer
2010-08-31 11:53           ` Solar Designer
2010-08-31 11:56         ` [PATCH] exec argument expansion can inappropriately triggerOOM-killer Tetsuo Handa

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