From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: segoon@openwall.com
Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
gregkh@suse.de, akpm@linux-foundation.org, davem@davemloft.net,
kernel-hardening@lists.openwall.com, jslaby@suse.cz,
jmorris@namei.org, neilb@suse.de, viro@zeniv.linux.org.uk,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] move RLIMIT_NPROC check from set_user() to do_execve_common()
Date: Wed, 13 Jul 2011 14:36:57 +0900 [thread overview]
Message-ID: <4E1D2EF9.3090201@jp.fujitsu.com> (raw)
In-Reply-To: <20110712132723.GA3193@albatros>
(2011/07/12 22:27), Vasiliy Kulikov wrote:
> The patch http://lkml.org/lkml/2003/7/13/226 introduced a RLIMIT_NPROC
> check in set_user() to check for NPROC exceeding via setuid() and
> similar functions. Before the check there was a possibility to greatly
> exceed the allowed number of processes by an unprivileged user if the
> program relied on rlimit only. But the check created new security
> threat: many poorly written programs simply don't check setuid() return
> code and believe it cannot fail if executed with root privileges. So,
> the check is removed in this patch because of too often privilege
> escalations related to buggy programs.
>
> The NPROC can still be enforced in the common code flow of daemons
> spawning user processes. Most of daemons do fork()+setuid()+execve().
> The check introduced in execve() enforces the same limit as in setuid()
> and doesn't create similar security issues.
>
> Similar check was introduced in -ow patches.
>
> Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
BSD folks tell me NetBSD has the exactly same hack (ie check at exec instead
setuid) since 2008. Then, I think this is enough proved safer way.
http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/kern/kern_exec.c?rev=1.316&content-type=text/x-cvsweb-markup&only_with_tag=MAIN
Thx.
prev parent reply other threads:[~2011-07-13 5:37 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-12 13:09 RLIMIT_NPROC check in set_user() Vasiliy Kulikov
2011-07-06 17:36 ` Vasiliy Kulikov
2011-07-06 18:01 ` Linus Torvalds
2011-07-06 18:59 ` [kernel-hardening] " Vasiliy Kulikov
2011-07-07 7:56 ` Vasiliy Kulikov
2011-07-07 8:19 ` Vasiliy Kulikov
2011-07-12 13:27 ` [PATCH] move RLIMIT_NPROC check from set_user() to do_execve_common() Vasiliy Kulikov
2011-07-12 21:16 ` Linus Torvalds
2011-07-12 23:14 ` NeilBrown
2011-07-13 6:31 ` Solar Designer
2011-07-13 7:06 ` NeilBrown
2011-07-13 20:46 ` Linus Torvalds
2011-07-14 0:11 ` James Morris
2011-07-14 1:27 ` NeilBrown
2011-07-14 15:06 ` Solar Designer
2011-07-15 3:30 ` NeilBrown
2011-07-15 5:35 ` Willy Tarreau
2011-07-15 6:31 ` [kernel-hardening] " Vasiliy Kulikov
2011-07-15 7:06 ` NeilBrown
2011-07-15 7:38 ` Vasiliy Kulikov
2011-07-15 13:04 ` Solar Designer
2011-07-15 13:58 ` [kernel-hardening] " Stephen Smalley
2011-07-15 15:26 ` Vasiliy Kulikov
2011-07-15 19:54 ` Stephen Smalley
2011-07-21 4:09 ` NeilBrown
2011-07-21 12:48 ` Solar Designer
2011-07-21 18:21 ` Linus Torvalds
2011-07-21 19:39 ` [kernel-hardening] " Solar Designer
2011-07-25 17:14 ` Vasiliy Kulikov
2011-07-25 23:40 ` [kernel-hardening] " Solar Designer
2011-07-26 0:47 ` NeilBrown
2011-07-26 1:16 ` Solar Designer
2011-07-26 4:11 ` NeilBrown
2011-07-26 14:48 ` [patch v2] " Vasiliy Kulikov
2011-07-27 2:15 ` NeilBrown
2011-07-29 7:07 ` [kernel-hardening] " Vasiliy Kulikov
2011-07-29 8:06 ` Vasiliy Kulikov
2011-07-29 8:11 ` [patch v3] " Vasiliy Kulikov
2011-07-29 8:17 ` James Morris
2011-07-14 1:30 ` [PATCH] " KOSAKI Motohiro
2011-07-13 5:36 ` KOSAKI Motohiro [this message]
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