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authorTyler Hicks <tyhicks@linux.vnet.ibm.com>2009-08-12 01:06:54 -0500
committerTyler Hicks <tyhicks@linux.vnet.ibm.com>2009-09-23 09:10:32 -0500
commitac22ba23b659e34a5961aec8c945608e471b0d5b (patch)
tree6629c15380fe2db238fa078e912f4cf393708161 /fs/ecryptfs/kthread.c
parentb0105eaefa7cce8f4a941d0fc6354b250d30e745 (diff)
downloadlinux-ac22ba23b659e34a5961aec8c945608e471b0d5b.tar.gz
eCryptfs: Check for O_RDONLY lower inodes when opening lower files
If the lower inode is read-only, don't attempt to open the lower file read/write and don't hand off the open request to the privileged eCryptfs kthread for opening it read/write. Instead, only try an unprivileged, read-only open of the file and give up if that fails. This patch fixes an oops when eCryptfs is mounted on top of a read-only mount. Acked-by: Serge Hallyn <serue@us.ibm.com> Cc: Eric Sandeen <esandeen@redhat.com> Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com> Cc: ecryptfs-devel@lists.launchpad.net Cc: stable <stable@kernel.org> Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>
Diffstat (limited to 'fs/ecryptfs/kthread.c')
-rw-r--r--fs/ecryptfs/kthread.c24
1 files changed, 8 insertions, 16 deletions
diff --git a/fs/ecryptfs/kthread.c b/fs/ecryptfs/kthread.c
index c6d7a4d748a0..e14cf7e588db 100644
--- a/fs/ecryptfs/kthread.c
+++ b/fs/ecryptfs/kthread.c
@@ -136,6 +136,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
const struct cred *cred)
{
struct ecryptfs_open_req *req;
+ int flags = O_LARGEFILE;
int rc = 0;
/* Corresponding dput() and mntput() are done when the
@@ -143,10 +144,14 @@ int ecryptfs_privileged_open(struct file **lower_file,
* destroyed. */
dget(lower_dentry);
mntget(lower_mnt);
- (*lower_file) = dentry_open(lower_dentry, lower_mnt,
- (O_RDWR | O_LARGEFILE), cred);
+ flags |= IS_RDONLY(lower_dentry->d_inode) ? O_RDONLY : O_RDWR;
+ (*lower_file) = dentry_open(lower_dentry, lower_mnt, flags, cred);
if (!IS_ERR(*lower_file))
goto out;
+ if (flags & O_RDONLY) {
+ rc = PTR_ERR((*lower_file));
+ goto out;
+ }
req = kmem_cache_alloc(ecryptfs_open_req_cache, GFP_KERNEL);
if (!req) {
rc = -ENOMEM;
@@ -180,21 +185,8 @@ int ecryptfs_privileged_open(struct file **lower_file,
__func__);
goto out_unlock;
}
- if (IS_ERR(*req->lower_file)) {
+ if (IS_ERR(*req->lower_file))
rc = PTR_ERR(*req->lower_file);
- dget(lower_dentry);
- mntget(lower_mnt);
- (*lower_file) = dentry_open(lower_dentry, lower_mnt,
- (O_RDONLY | O_LARGEFILE), cred);
- if (IS_ERR(*lower_file)) {
- rc = PTR_ERR(*req->lower_file);
- (*lower_file) = NULL;
- printk(KERN_WARNING "%s: Error attempting privileged "
- "open of lower file with either RW or RO "
- "perms; rc = [%d]. Giving up.\n",
- __func__, rc);
- }
- }
out_unlock:
mutex_unlock(&req->mux);
out_free: