Revert "ecryptfs: forbid opening files without mmap handler"

This reverts commit 2f36db71009304b3f0b95afacd8eba1f9f046b87.

It fixed a local root exploit but also introduced a dependency on
the lower file system implementing an mmap operation just to open a file,
which is a bit of a heavy hammer.  The right fix is to have mmap depend
on the existence of the mmap handler instead.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>

1 files changed, 2 insertions, 11 deletions

diff --git a/fs/ecryptfs/kthread.c b/fs/ecryptfs/kthread.c
index e818f5ac7a26..866bb18efefe 100644
--- a/fs/ecryptfs/kthread.c
+++ b/fs/ecryptfs/kthread.c
@@ -25,7 +25,6 @@
 #include <linux/slab.h>
 #include <linux/wait.h>
 #include <linux/mount.h>
-#include <linux/file.h>
 #include "ecryptfs_kernel.h"
 
 struct ecryptfs_open_req {
@@ -148,7 +147,7 @@ int ecryptfs_privileged_open(struct file **lower_file,
         flags |= IS_RDONLY(d_inode(lower_dentry)) ? O_RDONLY : O_RDWR;
         (*lower_file) = dentry_open(&req.path, flags, cred);
         if (!IS_ERR(*lower_file))
-                goto have_file;
+                goto out;
         if ((flags & O_ACCMODE) == O_RDONLY) {
                 rc = PTR_ERR((*lower_file));
                 goto out;
@@ -166,16 +165,8 @@ int ecryptfs_privileged_open(struct file **lower_file,
         mutex_unlock(&ecryptfs_kthread_ctl.mux);
         wake_up(&ecryptfs_kthread_ctl.wait);
         wait_for_completion(&req.done);
-        if (IS_ERR(*lower_file)) {
+        if (IS_ERR(*lower_file))
                 rc = PTR_ERR(*lower_file);
-                goto out;
-        }
-have_file:
-        if ((*lower_file)->f_op->mmap == NULL) {
-                fput(*lower_file);
-                *lower_file = NULL;
-                rc = -EMEDIUMTYPE;
-        }
 out:
         return rc;
 }