fscrypto: lock inode while setting encryption policy

i_rwsem needs to be acquired while setting an encryption policy so that
concurrent calls to FS_IOC_SET_ENCRYPTION_POLICY are correctly
serialized (especially the ->get_context() + ->set_context() pair), and
so that new files cannot be created in the directory during or after the
->empty_dir() check.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: Richard Weinberger <richard@nod.at>
Cc: stable@vger.kernel.org
This commit is contained in:
Eric Biggers 2016-10-15 09:48:50 -04:00 committed by Theodore Ts'o
parent 199625098a
commit 8906a8223a

View File

@ -109,6 +109,8 @@ int fscrypt_process_policy(struct file *filp,
if (ret)
return ret;
inode_lock(inode);
if (!inode_has_encryption_context(inode)) {
if (!S_ISDIR(inode->i_mode))
ret = -EINVAL;
@ -127,6 +129,8 @@ int fscrypt_process_policy(struct file *filp,
ret = -EINVAL;
}
inode_unlock(inode);
mnt_drop_write_file(filp);
return ret;
}