KEYS: Don't permit request_key() to construct a new keyring

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@redhat.com>
Cc: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 381411941cc1abbc48a699b1c2c38042f1a05711..9ea60a7bac780e32c47d1ca5f073d5d4d7204d75 100644 (file)
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -457,6 +457,9 @@ static struct key *construct_key_and_link(struct keyring_search_context *ctx,
 
        kenter("");
 
+       if (ctx->index_key.type == &key_type_keyring)
+               return ERR_PTR(-EPERM);
+       
        user = key_user_lookup(current_fsuid());
        if (!user)
                return ERR_PTR(-ENOMEM);