On Thu, 2011-04-28 at 10:03 -0700, Casey Schaufler wrote: > On 4/28/2011 6:30 AM, Stephen Smalley wrote: > > On Tue, 2011-04-26 at 20:15 -0700, Casey Schaufler wrote: > >> I have been tracking down an problem that we've been seeing > >> with Smack on top of btrfs and have narrowed it down to a check > >> in smack_d_instantiate() that checks to see if the underlying > >> filesystem supports extended attributes by looking at > >> > >> inode->i_op->getxattr > >> > >> If the filesystem has no entry for getxattr it is assumed that > >> it does not support extended attributes. The Smack code clearly > >> finds this value to be NULL for btrfs and uses a fallback value. > >> Clearly something is amiss, as other code paths clearly find the > >> i_op->getxattr function and use it to effect. The btrfs code > >> quite obviously includes getxattr functions. > >> > >> So, what is btrfs up to such that the inode ops does not include > >> getxattr when security_d_instantiate is called? I am led to > >> understand that SELinux has worked around this, but looking at > >> the SELinux code I expect that there is a problem there as well. > >> > >> Thank you. > > kernel version(s)? > > 2.6.37 > 2.6.39rc4 > > > reproducer? > > The MeeGo team saw the behavior first. I have been instrumenting > the Smack code to track down what is happening. I am in the process > of developing a Smack workaround for the btrfs behavior.
If this is for newly created files, then we initialize the in-core security label for the inode as part of the inode_init_security hook in SELinux and thus don't even try to call ->getxattr at d_instantiate time. Not sure though why it wouldn't already be set. -- Stephen Smalley National Security Agency -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
