diff options
| author | Josef Bacik <josef@redhat.com> | 2010-11-18 20:52:55 -0500 |
|---|---|---|
| committer | AK <andi@firstfloor.org> | 2011-03-31 11:58:48 -0700 |
| commit | 0fce96e0a736b60c49c4a1f8a37be56fe02d02b7 (patch) | |
| tree | 1e5c68c8e9b0dc502ef1ea0982294aab6e86d094 /fs | |
| parent | 4214a0da0bdd0a7d11a7b560dfed69617d2a6dab (diff) | |
fs: call security_d_instantiate in d_obtain_alias V2
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 <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Chuck Ebbert <cebbert@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/dcache.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 86d4db15473e..c1f86c734540 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -1186,9 +1186,12 @@ struct dentry *d_obtain_alias(struct inode *inode) 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; } |