Messages in this thread | | | Date | Sat, 26 Mar 2011 12:11:31 -0400 | From | Josef Bacik <> | Subject | Re: [34/35] fs: call security_d_instantiate in d_obtain_alias V2 |
| |
On Fri, Mar 25, 2011 at 05:24:56PM -0700, Casey Schaufler wrote: > On 3/25/2011 5:04 PM, Greg KH wrote: > > 2.6.33-longterm review patch. If anyone has any objections, please let us know. > > > > ------------------ > > > > From: Josef Bacik <josef@redhat.com> > > > > commit 24ff6663ccfdaf088dfa7acae489cb11ed4f43c4 upstream. > > > > While trying to track down some NFS problems with BTRFS, I kept noticing I was > > getting -EACCESS for no apparent reason. Eric Paris and printk() helped me > > figure out that it was SELinux that was giving me grief, with the following > > denial > > > > type=AVC msg=audit(1290013638.413:95): avc: denied { 0x800000 } for pid=1772 > > comm="nfsd" name="" dev=sda1 ino=256 scontext=system_u:system_r:kernel_t:s0 > > tcontext=system_u:object_r:unlabeled_t:s0 tclass=file > > > > Turns out this is because in d_obtain_alias if we can't find an alias we create > > one and do all the normal instantiation stuff, but we don't do the > > security_d_instantiate. > > > > Usually we are protected from getting a hashed dentry that hasn't yet run > > security_d_instantiate() by the parent's i_mutex, but obviously this isn't an > > option there, so in order to deal with the case that a second thread comes in > > and finds our new dentry before we get to run security_d_instantiate(), we go > > ahead and call it if we find a dentry already. Eric assures me that this is ok > > as the code checks to see if the dentry has been initialized already so calling > > security_d_instantiate() against the same dentry multiple times is ok. With > > this patch I'm no longer getting errant -EACCESS values. > > Not to be a bother, but did you try this with Smack as well as SELinux? > Smack should be fine with the change, but if you're not going to try > Smack I need to know. >
I only tested SELinux since it's on by default in fedora. Thanks,
Josef
| |