Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 23 Jul 2014 08:43:25 +0200
From: Sebastian Krahmer <>
Subject: Re: Re: Linux peer_cred Mischmasch

On Tue, Jul 22, 2014 at 12:22:30PM -0700, Andy Lutomirski wrote:
> On 07/22/2014 04:17 AM, Florian Weimer wrote:
> > On 07/22/2014 12:15 PM, Sebastian Krahmer wrote:
> >> While maybe_add_creds() (via SOCK_PASSCRED) and scm_send()
> >> (via unix_{stream,dgram}_sendmsg()) use the real UID,
> >>
> >> cred_to_ucred() (via SO_PEERCRED) passes the EUID (this time
> >> also kuid_munged()).
> > 
> > There should also be a discrepancy regarding when the credentials are
> > captured (time of send for SOCK_PASSCRED, time of socket creation for
> > SO_PEERCRED).  The latter is required because privileged processes
> > assume that they can safely write to stderr, so picking the current
> > process credentials may well introduce vulnerabilities.

It does, and that should be ok.

> > 
> Indeed.  IMO both of these interfaces are flawed, but PASSCRED is
> terminally broken and should never be used.  See, for example,
> CVE-2013-1979, which is the immediate cause of the ruid thing.

Thats what I was wondering whether CVE-2013-1979 only fixed SCM_CREDENTIALS
case and missed to fix SO_PEERCRED.
I am not fully convinced thats OK to get one time the euid and another time
the uid (even though I liked the spy example:)



~ perl
~ $_='print"\$_=\47$_\47;eval"';eval
~ - SuSE Security Team

Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.