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Subject[34-longterm 049/209] eCryptfs: Clear LOOKUP_OPEN flag when creating lower file
Date
From: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

=====================================================================
| This is a commit scheduled for the next v2.6.34 longterm release. |
| If you see a problem with using this for longterm, please comment.|
=====================================================================

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@linux.vnet.ibm.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
fs/ecryptfs/inode.c | 4 ++++
1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index 21801ee..31c8b2f 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -70,15 +70,19 @@ ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
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;
}

--
1.7.4.4


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