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 <[email protected]> > > 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. > Signed-off-by: Josef Bacik <[email protected]> > Signed-off-by: Al Viro <[email protected]> > Cc: Chuck Ebbert <[email protected]> > Signed-off-by: Greg Kroah-Hartman <[email protected]> > > --- > fs/dcache.c | 3 +++ > 1 file changed, 3 insertions(+) > > --- a/fs/dcache.c > +++ b/fs/dcache.c > @@ -1176,9 +1176,12 @@ struct dentry *d_obtain_alias(struct ino > spin_unlock(&tmp->d_lock); > > spin_unlock(&dcache_lock); > + security_d_instantiate(tmp, inode); > return tmp; > > out_iput: > + if (res && !IS_ERR(res)) > + security_d_instantiate(res, inode); > iput(inode); > return res; > } > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > > _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
