BugLink: http://bugs.launchpad.net/bugs/1729107
commit
ba63f23d69a3a10e7e527a02702023da68ef8a6d upstream.
[Please apply to 4.4-stable. Note: this was already backported, but
only to ext4; it was missed that it should go to f2fs as well. This is
needed to make xfstest generic/395 pass on f2fs.]
Since setting an encryption policy requires writing metadata to the
filesystem, it should be guarded by mnt_want_write/mnt_drop_write.
Otherwise, a user could cause a write to a frozen or readonly
filesystem. This was handled correctly by f2fs but not by ext4. Make
fscrypt_process_policy() handle it rather than relying on the filesystem
to get it right.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Acked-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
sizeof(policy)))
return -EFAULT;
+ err = mnt_want_write_file(filp);
+ if (err)
+ return err;
+
mutex_lock(&inode->i_mutex);
err = f2fs_process_policy(&policy, inode);
mutex_unlock(&inode->i_mutex);
+ mnt_drop_write_file(filp);
+
return err;
#else
return -EOPNOTSUPP;