[PATCH 3.18 10/69] KEYS: Dont permit request_key() to construct a new keyring

[Greg Kroah-Hartman]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@xxxxxxxxxx>

commit 911b79cde95c7da0ec02f48105358a36636b7a71 upstream.

If request_key() is used to find a keyring, only do the search part - don't
do the construction part if the keyring was not found by the search.  We
don't really want keyrings in the negative instantiated state since the
rejected/negative instantiation error value in the payload is unioned with
keyring metadata.

Now the kernel gives an error:

	request_key("keyring", "#selinux,bdekeyring", "keyring", KEY_SPEC_USER_SESSION_KEYRING) = -1 EPERM (Operation not permitted)

Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 security/keys/request_key.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -467,6 +467,9 @@ static struct key *construct_key_and_lin
 	if (ret)
 		goto error;
 
+	if (ctx->index_key.type == &key_type_keyring)
+		return ERR_PTR(-EPERM);
+
 	user = key_user_lookup(current_fsuid());
 	if (!user) {
 		ret = -ENOMEM;