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From: "H. Peter Anvin" <hpa@zytor.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: akpm@linux-foundation.org, serue@us.ibm.com,
	viro@ftp.linux.org.uk, linuxram@us.ibm.com,
	ebiederm@xmission.com, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, containers@lists.osdl.org
Subject: Re: [patch] unprivileged mounts update
Date: Wed, 25 Apr 2007 09:55:06 -0700	[thread overview]
Message-ID: <462F87EA.1000002@zytor.com> (raw)
In-Reply-To: <E1HgjG0-0005CN-00@dorka.pomaz.szeredi.hu>

Miklos Szeredi wrote:
> 
> Andrew, please skip this patch, for now.
> 
> Serge found a problem with the fsuid approach: setfsuid(nonzero) will
> remove filesystem related capabilities.  So even if root is trying to
> set the "user=UID" flag on a mount, access to the target (and in case
> of bind, the source) is checked with user privileges.
> 
> Root should be able to set this flag on any mountpoint, _regardless_
> of permissions.
> 

Right, if you're using fsuid != 0, you're not running as root (fsuid is
the equivalent to euid for the filesystem.)

I fail to see how ruid should have *any* impact on mount(2).  That seems
to be a design flaw.

	-hpa

  reply	other threads:[~2007-04-25 16:58 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-04-25  7:45 Miklos Szeredi
2007-04-25 15:18 ` Miklos Szeredi
2007-04-25 16:55   ` H. Peter Anvin [this message]
2007-04-25 17:20     ` Serge E. Hallyn
2007-04-25 17:46       ` Eric W. Biederman
2007-04-25 17:56         ` Serge E. Hallyn
2007-04-25 18:41           ` Eric W. Biederman
2007-04-25 18:52             ` Serge E. Hallyn
2007-04-25 19:33               ` Miklos Szeredi
2007-04-26 14:57                 ` Serge E. Hallyn
2007-04-26 15:23                   ` Miklos Szeredi
2007-04-26 16:19                     ` Serge E. Hallyn
2007-04-26 16:29                       ` Miklos Szeredi
2007-04-26 19:42                         ` Serge E. Hallyn
2007-04-26 19:56                           ` Miklos Szeredi
2007-04-27  2:10                             ` Serge E. Hallyn
2007-04-25 17:21   ` Eric W. Biederman
2007-04-25 17:30     ` Serge E. Hallyn
2007-04-26 19:10     ` Jan Engelhardt
2007-04-26 20:27       ` Miklos Szeredi
2007-04-27  4:10         ` Eric W. Biederman
2007-04-27  7:01         ` Jan Engelhardt
2007-04-25 19:33   ` Andrew Morton
2007-04-25 19:45     ` Miklos Szeredi

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