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. 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; } _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
