What makes contexts different for audit.log and ls -Z?

[Stephen Smalley]

On Wed, 2006-02-08 at 14:32 +0100, Göran Uddeborg wrote:
> What could cause the context shown with "ls" and the context reported
> for an denied AVC check to differ?
> 
> After a recent upgrade, Samba stopped working for us.  Trying
> smbclient user adb is not allowed to access it's home directory.  From
> an strace of smbd I see that a stat() call fails:
> 
>     8307  stat64("/home/adb", 0xbff08334)   = -1 EACCES (Permission denied)
> 
> I believe I found the reason in audit.log:
> 
>     type=AVC msg=audit(1139403413.095:1782): avc:  denied  { search } for  pid=8647 comm="smbd" name="home" dev=hda2 ino=966657 scontext=root:system_r:smbd_t tcontext=system_u:object_r:home_root_t tclass=dir
>     type=SYSCALL msg=audit(1139403413.095:1782): arch=40000003 syscall=195 success=no exit=-13 a0=90f7110 a1=bff08334 a2=5baff4 a3=bff08334 items=1 pid=8647 auid=504 uid=734 gid=0 euid=734 suid=0 fsuid=734 egid=734 sgid=734 fsgid=734 comm="smbd" exe="/usr/sbin/smbd"
>     type=CWD msg=audit(1139403413.095:1782):  cwd="/"
>     type=PATH msg=audit(1139403413.095:1782): item=0 name="/home/adb" flags=1  inode=966657 dev=03:02 mode=040755 ouid=0 ogid=0 rdev=00:00

If you look closely at the AVC audit message (which admittedly is
inscrutable ;), you'll see that the component on which search failed was
for "home", not "/home/adb".  You have to be able to search /home to
reach /home/adb.  Try 'man samba_selinux' and following the instructions
there for modifying the relevant boolean.

-- 
Stephen Smalley
National Security Agency