Re: Stuff I found in my log?

[Paul Howarth <paul city-fan org>]

Daniel J Walsh wrote:
> Paul Howarth wrote:
> > On Tue, 2006-05-23 at 17:12 -0700, Knute Johnson wrote:
> >  
> > > I found some interesting things in my 'messages' log today.  I'm not 
> > > sure what they mean and would appreciate any information.
> > >
> > > This one is the most bothersome.  It appears that 'useradd' was 
> > > prevented from running this morning only I didn't run it.  Would any 
> > > other programs run 'useradd' and what would cause it to be denied?
> > >
> > > May 23 05:11:49 rabbitbrush kernel: audit(1148386309.877:556): avc:  
> > > denied  { write } for  pid=13906 comm="useradd" name="[1708464]" 
> > > dev=pipefs ino=1708464 scontext=user_u:system_r:useradd_t:s0 
> > > tcontext=user_u:system_r:unconfined_t:s0 tclass=fifo_file
> > >     
> >
> > useradd is often run in the pre-install scripts of rpm packages when the
> > package provides something that runs as a service. You probably updated
> > such a package (or yum did it automatically in the overnight run). For
> > instance, I got one of these when avahi was updated recently. The
> > pre-install script for the avahi package is:
> >
> > # Add the "avahi" user
> > /usr/sbin/useradd -c 'Avahi daemon' -u 70 \
> >         -s /sbin/nologin -r -d '/' avahi 2> /dev/null || :
> >
> > The denial is coming because useradd is trying to write its output to a
> > pipe, which is not allowed by policy. Perhaps it should be?
> >
> > Anyway, I think this one's harmless.
> >
> >   
> The problem with that theory is you would expect it to be talking to 
> rpm_script_t or rpm_t.  Probably a leaked
> descriptor that useradd does not need to talk to, but applications that 
> are handed open descriptors some times check their
> access, which could cause an AVC.

Are you sure? rpm.te has:

usermanage_domtrans_useradd(rpm_script_t)

at least in serefpolicy-2.2.23 (don't have an up to date one to hand)

> > > There are a boatload of these messages.  I know that 'webalizer' is a 
> > > statistics formatter for the web server but why would it be run 
> > > dozens of times and be denied?
> > >
> > > May 23 04:02:02 rabbitbrush kernel: audit(1148382121.861:514): avc:  
> > > denied  { create } for  pid=12313 comm="webalizer" 
> > > scontext=user_u:system_r:webalizer_t:s0 
> > > tcontext=user_u:system_r:webalizer_t:s0 tclass=netlink_route_socket
> > >     
> >
> > I get these too. I asked about it yesterday but no response yet. Looking
> > at the policy for other packages, and bearing in mind that webalizer
> > still seems to work despite the denials, I suspect that these can be
> > dontaudit-ed, but I'd like to know what they are first.
> >   
> This means webalizer is trying to look at the routing table.  Not sure 
> whether it matters whether it can or can not.  Not that
> valuable of information so I will probably allow.

OK, I'll add it locally for now too, to make my audit logs a lot smaller :-)

Paul.