From: Josef Bacik Date: Fri, 19 Nov 2010 01:52:55 +0000 (-0500) Subject: fs: call security_d_instantiate in d_obtain_alias V2 X-Git-Tag: v2.6.37.6~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6b0b6741726daad876d5443aae2ffe4efa328f01;p=pandora-kernel.git 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 Signed-off-by: Al Viro Cc: Chuck Ebbert Signed-off-by: Greg Kroah-Hartman --- Reading git-diff-tree failed