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>

diff --git a/fs/ecryptfs/kthread.c b/fs/ecryptfs/kthread.c
index e818f5a..866bb18 100644 (file)
--- 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;
 }