linux-kernel - Re: [PATCH 2/2] KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 01 Aug 2013 13:54:20 -0400
From:	Daniel Kahn Gillmor <dkg@...thhorseman.net>
To:	David Howells <dhowells@...hat.com>
CC:	keyrings@...ux-nfs.org, linux-nfs@...r.kernel.org, krbdev@....edu,
	"Serge E. Hallyn" <serge.hallyn@...ntu.com>,
	linux-kernel@...r.kernel.org, simo@...hat.com,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [PATCH 2/2] KEYS: Add per-user_namespace registers for persistent
 per-UID kerberos caches

On 08/01/2013 01:39 PM, David Howells wrote:
> The uid is -1 or the user's own UID for the user's own cache or the uid of some
> other user's cache (requires CAP_SETUID).  This permits rpc.gssd or whatever to
> mess with the cache.

Is the goal here eventually to be able to avoid the upcall to rpc.gssd
entirely?  It seems a little bit roundabout to have the kernel call up
into userspace for the credentials, only to talk to a process which then
calls back into the kernel for something that the kernel has already
well-defined internally.

It seems like a non-privileged user could use this to store arbitrary
data in this keyring as a way of hiding what would otherwise be
filesystem activity or using it for some sort of odd/sneaky IPC
mechanism.  Is this an intentional side effect?

Sorry if these are obvious questions.  feel free to point me to
already-documented answers if they exist.

Thanks for all your work on this!

Regards,

	--dkg

Download attachment "signature.asc" of type "application/pgp-signature" (1028 bytes)