Re: [E1000-devel] networking probs in next-20081203

[Stephen Smalley <sds@tycho.nsa.gov>]

On Fri, 2008-12-12 at 20:26 +1100, James Morris wrote:
> On Fri, 12 Dec 2008, Alexey Dobriyan wrote:
> 
> > Yes, please, someone test it.
> 
> Still getting avc denials:
> 
> avc:  denied  { mount } for  pid=2308 comm="dhclient" name="/" 
> dev=proc/net ino=4026531842 scontext=unconfined_u:system_r:dhcpc_t:s0-s0:c0.c1023 
> tcontext=system_u:object_r:proc_t:s0 tclass=filesystem
> type=SYSCALL msg=audit(1229073699.174:53): arch=c000003e syscall=2 
> success=no exit=-2 a0=45bef7 a1=80000 a2=1b6 a3=7f296
> e71c6f0 items=0 ppid=2259 pid=2308 auid=0 uid=0 gid=0 euid=0 suid=0 
> fsuid=0 egid=0 sgid=0 fsgid=0 tty=ttyS0 ses=1 comm="
> dhclient" exe="/sbin/dhclient" 
> subj=unconfined_u:system_r:dhcpc_t:s0-s0:c0.c1023 key=(null)
> 
> It seems the problem is that the /proc/net mountpoint is now labeled as 
> proc_t.

No, that's a check against the filesystem (superblock) label, not the
mountpoint directory.

proc_net_follow_link() creates a new mount, so we end up hitting
security_sb_kern_mount() => selinux_sb_kern_mount() and triggering this
permission check in the context of the current process on what is
supposed to be a kernel-internal mount of /proc/net.

Maybe pass flags down to security_sb_kern_mount() and skip the check in
the MS_KERNMOUNT case?

-- 
Stephen Smalley
National Security Agency