This is a note to let you know that I've just added the patch titled
fs: call security_d_instantiate in d_obtain_alias V2
to the 2.6.33-longterm tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/longterm/longterm-queue-2.6.33.git;a=summary
The filename of the patch is:
fs-call-security_d_instantiate-in-d_obtain_alias-v2.patch
and it can be found in the queue-2.6.33 subdirectory.
If you, or anyone else, feels it should not be added to the 2.6.33 longterm
tree,
please let <[email protected]> know about it.
>From 24ff6663ccfdaf088dfa7acae489cb11ed4f43c4 Mon Sep 17 00:00:00 2001
From: Josef Bacik <[email protected]>
Date: Thu, 18 Nov 2010 20:52:55 -0500
Subject: fs: call security_d_instantiate in d_obtain_alias V2
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;
}
Patches currently in longterm-queue-2.6.33 which might be from [email protected]
are
/home/gregkh/linux/longterm/longterm-queue-2.6.33/queue-2.6.33/fs-call-security_d_instantiate-in-d_obtain_alias-v2.patch
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