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>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 2e6eefda4f50f4cbcecd35a0de37cb01d120a0b0..3ca46e5e43dc5eee6e72146a8db72480381bb0af 100644 (file)
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -467,6 +467,9 @@ static struct key *construct_key_and_link(struct keyring_search_context *ctx,
        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;