[refpolicy] Debian: ldd /sbin/udevd, need to use interactive fds

Václav Ovsík vaclav.ovsik at i.cz
Wed Sep 3 08:52:37 CDT 2008


On Wed, Sep 03, 2008 at 12:22:25PM +0100, Martin Orr wrote:
> On 02/09/08 14:19, Christopher J. PeBenito wrote:
> > On Mon, 2008-09-01 at 19:12 +0200, Václav Ovsík wrote:
> >> I am running Debian unstable (Sid) with latest refpolicy packaged by
> >> Russel Coker (2:0.0.20080702-6) with unconfined module (permissive
> >> mode). I have caught problem with running update-initramfs under
> >> unconfined user (system initrd image generation). The hook script udev
> >> is trying to discover libraries used by udev running command "ldd
> >> /sbin/udev", which emits:
> >>
> >> [  180.506850] type=1400 audit(1219673765.136:5): avc:  denied  { use } for  pid=1944 comm="udevd" path="/dev/tty1" dev=tmpfs ino=998 scontext=unconfined_u:system_r:udev_t:s0-s0:c0.c1023 tcontext=system_u:system_r:getty_t:s0 tclass=fd
> >> [  180.534524] type=1300 audit(1219673765.136:5): arch=40000003 syscall=11 success=yes exit=0 a0=8f93ee8 a1=8f93e68 a2=8f7d008 a3=0 items=0 ppid=1936 pid=1944 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=tty1 ses=4294967295 comm="udevd" exe="/sbin/udevd" subj=unconfined_u:system_r:udev_t:s0-s0:c0.c1023 key=(null)
> >>
> >> One wants to see output from udevd --help e.g. also...
> >> So attached is a patch.
> > 
> > The denials aren't consistent with 'ldd /sbin/udev', otherwise comm=
> > would be ldd.  I also can't reproduce this type of denial while using
> > ldd.  As for 'ldd --help', there shouldn't really be a transition.  In
> > fact I think Dan may have suggested removing the domain transition from
> > DIRECT_INITRC and just leave a role transition.
> 
> ldd is just a shell script, which does "LD_TRACE_LOADED_OBJECTS=1 $cmd" (you
> can run that on the command line if you want).  Setting
> LD_TRACE_LOADED_OBJECTS causes the dynamic linker to link the program and
> output the objects it has linked but then exit without calling main().
> 
> Since $cmd is never properly executed, it doesn't make sense to be
> transitioning to its domain.  So I think ldd should have a domain of its
> own, which has no privileges except to write to the terminal and to
> execute_no_trans everything.
> -- 
> Martin Orr

Hmm, it sounds like the right way to solve this.
Maybe this could solve the problem with the transition to rsync_t from user
domains while rsync is running over ssh. Great.
Thanks for suggestion.
-- 
Zito


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