[PATCH 3.10 160/319] btrfs: ensure that file descriptor used with subvol ioctls is a dir

Willy Tarreau
2017-02-05T20:19:04Z

From: Jeff Mahoney <jeffm@suse.com>

commit 325c50e3cebb9208009083e841550f98a863bfa0 upstream.

If the subvol/snapshot create/destroy ioctls are passed a regular file
with execute permissions set, we'll eventually Oops while trying to do
inode->i_op->lookup via lookup_one_len.

This patch ensures that the file descriptor refers to a directory.

Fixes: cb8e70901d (Btrfs: Fix subvolume creation locking rules)
Fixes: 76dda93c6a (Btrfs: add snapshot/subvolume destroy ioctl)
Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Chris Mason <clm@fb.com>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
fs/btrfs/ioctl.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index dbefa6c..296cc1b 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1496,6 +1496,9 @@ static noinline int btrfs_ioctl_snap_create_transid(struct file *file,
int namelen;
int ret = 0;

+ if (!S_ISDIR(file_inode(file)->i_mode))
+ return -ENOTDIR;
+
ret = mnt_want_write_file(file);
if (ret)
goto out;
@@ -1553,6 +1556,9 @@ static noinline int btrfs_ioctl_snap_create(struct file *file,
struct btrfs_ioctl_vol_args *vol_args;
int ret;

+ if (!S_ISDIR(file_inode(file)->i_mode))
+ return -ENOTDIR;
+
vol_args = memdup_user(arg, sizeof(*vol_args));
if (IS_ERR(vol_args))
return PTR_ERR(vol_args);
@@ -1576,6 +1582,9 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file,
bool readonly = false;
struct btrfs_qgroup_inherit *inherit = NULL;

+ if (!S_ISDIR(file_inode(file)->i_mode))
+ return -ENOTDIR;
+
vol_args = memdup_user(arg, sizeof(*vol_args));
if (IS_ERR(vol_args))
return PTR_ERR(vol_args);
@@ -2081,6 +2090,9 @@ static noinline int btrfs_ioctl_snap_destroy(struct file *file,
int ret;
int err = 0;

+ if (!S_ISDIR(dir->i_mode))
+ return -ENOTDIR;
+
vol_args = memdup_user(arg, sizeof(*vol_args));
if (IS_ERR(vol_args))
return PTR_ERR(vol_args);
--
2.8.0.rc2.1.gbe9624a