linux-kernel - [PATCH] [88/223] eCryptfs: Clear LOOKUP

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Message-Id: <20101212234627.CC56EB27BF@basil.firstfloor.org>
Date:	Mon, 13 Dec 2010 00:46:27 +0100 (CET)
From:	Andi Kleen <andi@...stfloor.org>
To:	tyhicks@...ux.vnet.ibm.com, gregkh@...e.de, ak@...ux.intel.com,
	linux-kernel@...r.kernel.org, stable@...nel.org
Subject: [PATCH] [88/223] eCryptfs: Clear LOOKUP_OPEN flag when creating lower file

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Tyler Hicks <tyhicks@...ux.vnet.ibm.com>

commit 2e21b3f124eceb6ab5a07c8a061adce14ac94e14 upstream.

eCryptfs was passing the LOOKUP_OPEN flag through to the lower file
system, even though ecryptfs_create() doesn't support the flag. A valid
filp for the lower filesystem could be returned in the nameidata if the
lower file system's create() function supported LOOKUP_OPEN, possibly
resulting in unencrypted writes to the lower file.

However, this is only a potential problem in filesystems (FUSE, NFS,
CIFS, CEPH, 9p) that eCryptfs isn't known to support today.

https://bugs.launchpad.net/ecryptfs/+bug/641703

Reported-by: Kevin Buhr
Signed-off-by: Tyler Hicks <tyhicks@...ux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

---
 fs/ecryptfs/inode.c |    4 ++++
 1 file changed, 4 insertions(+)

Index: linux/fs/ecryptfs/inode.c
===================================================================
--- linux.orig/fs/ecryptfs/inode.c
+++ linux/fs/ecryptfs/inode.c
@@ -70,15 +70,19 @@ ecryptfs_create_underlying_file(struct i
 	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
 	struct dentry *dentry_save;
 	struct vfsmount *vfsmount_save;
+	unsigned int flags_save;
 	int rc;
 
 	dentry_save = nd->path.dentry;
 	vfsmount_save = nd->path.mnt;
+	flags_save = nd->flags;
 	nd->path.dentry = lower_dentry;
 	nd->path.mnt = lower_mnt;
+	nd->flags &= ~LOOKUP_OPEN;
 	rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
 	nd->path.dentry = dentry_save;
 	nd->path.mnt = vfsmount_save;
+	nd->flags = flags_save;
 	return rc;
 }
 
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