From: Al Viro <viro@ZenIV.linux.org.uk>
To: Kees Cook <kees.cook@canonical.com>
Cc: Eric Paris <eparis@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
James Morris <jmorris@namei.org>,
linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org,
Randy Dunlap <rdunlap@xenotime.net>,
Andrew Morton <akpm@linux-foundation.org>,
Jiri Kosina <jkosina@suse.cz>,
Dave Young <hidave.darkstar@gmail.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
David Howells <dhowells@redhat.com>, Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Tim Gardner <tim.gardner@canonical.com>,
"Serge E. Hallyn" <serue@us.ibm.com>
Subject: Re: [PATCH v3] fs: allow protected cross-uid sticky symlinks
Date: Tue, 1 Jun 2010 22:45:27 +0100 [thread overview]
Message-ID: <20100601214527.GU31073@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20100601210734.GD4098@outflux.net>
On Tue, Jun 01, 2010 at 02:07:34PM -0700, Kees Cook wrote:
> > I don't buy it. If we are concerned about the symlinks in the middle of
> > pathname, your checks are useless (mkdir /tmp/a, ln -s whatever /tmp/a/b,
> > have victim open /tmp/a/b/something). If we are not, then your checks are
> > in the wrong place.
>
> Well, that's not traditionally where the problems happen, but I have no
> problem strengthening the protection to include a full examination of the
> entire path looking for sticky/world-writable directories.
>
> If not, what is the right place for the checks?
Handling of trailing symlink on open(). At most. And I wouldn't be
surprised if the real answer turns out to include "... if we have
O_CREAT in flags", but that needs to be determined.
next prev parent reply other threads:[~2010-06-01 21:45 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-01 18:52 [PATCH v3] fs: allow protected cross-uid sticky symlinks Kees Cook
2010-06-01 19:01 ` Al Viro
2010-06-01 21:07 ` Kees Cook
2010-06-01 21:45 ` Al Viro [this message]
2010-06-01 22:20 ` Kees Cook
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