From: dwalsh@redhat.com (Daniel J Walsh)
To: refpolicy@oss.tresys.com
Subject: [refpolicy] chsh (chfn_t) to access /etc/.pwd.lock (shadow_t) ?
Date: Tue, 27 Mar 2012 16:31:31 -0400 [thread overview]
Message-ID: <4F7223A3.9090409@redhat.com> (raw)
In-Reply-To: <20120327192447.GA2101@siphos.be>
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
On 03/27/2012 03:24 PM, Sven Vermeulen wrote:
> In Gentoo, we notice that recent shadow package (version 4.1.5) has a change in behavior for changing account information through chsh. Although the application only edits /etc/passwd entries, it now uses the /etc/.pwd.lock file to prevent concurrent changes to the /etc/passwd (and other account-related files).
>
> In the current policy however, /etc/.pwd.lock is marked as shadow_t, so the chsh application (running in chfn_t) does not have the proper privileges to work on this. As a result, it fails to update /etc/passwd entries.
>
> As I'm not going to give it read/write access to shadow_t files, one other possibility would be to mark /etc/.pwd.lock as etc_t. But I can imagine that it was given shadow_t on purpose previously, probably to prevent a malicious program (that has write access to etc_t) to update the lock file so concurrent write operations on /etc/shadow could result in corruption...
>
> Another solution would be to patch chsh itself to use a different lock file, but unless it's accepted upstream, it's only a "local" remedy.
>
> A third solution would be to create and use a different type for it, like etc_auth_lock_t or whatever imagination can bring to life, and update the policies of all domains that need access to it towards it.
>
> Any thoughts on this?
>
> Wkr, Sven Vermeulen
>
> _______________________________________________ refpolicy mailing list refpolicy at oss.tresys.com http://oss.tresys.com/mailman/listinfo/refpolicy
Being able to write to etc_t is basically the same as being able to write to shadow_t, if /etc/passwd is labeled as etc_t.
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.12 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/
iEYEARECAAYFAk9yI6MACgkQrlYvE4MpobPOegCg6i+NN+phGriaJl5W4/5N9xB5
16EAn27LFy9tO/aO+UEw5HXIjjrmqNHX
=oEnZ
-----END PGP SIGNATURE-----
next prev parent reply other threads:[~2012-03-27 20:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-27 19:24 [refpolicy] chsh (chfn_t) to access /etc/.pwd.lock (shadow_t) ? Sven Vermeulen
2012-03-27 20:31 ` Daniel J Walsh [this message]
2012-03-28 16:52 ` Sven Vermeulen
2012-03-28 17:15 ` Daniel J Walsh
2012-03-27 23:47 ` Russell Coker
2012-03-27 23:51 ` Russell Coker
2012-03-28 16:53 ` Sven Vermeulen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4F7223A3.9090409@redhat.com \
--to=dwalsh@redhat.com \
--cc=refpolicy@oss.tresys.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.