linux-kernel - [PATCH] fs: call security_d_instantiate in d_obtain

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Date:	Wed, 17 Nov 2010 12:51:03 -0500
From:	Josef Bacik <josef@...hat.com>
To:	linux-fsdevel@...r.kernel.org, eparis@...hat.com,
	linux-kernel@...r.kernel.org
Subject: [PATCH] fs: call security_d_instantiate in d_obtain_alias

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.  With this patch I'm no longer seeing these errant
-EACCESS return values.  Thanks,

Signed-off-by: Josef Bacik <josef@...hat.com>
---
 fs/dcache.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 23702a9..890a59e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1201,6 +1201,7 @@ 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:
-- 
1.6.6.1

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