KEYS: Add a 'trusted' flag and a 'trusted only' flag
Add KEY_FLAG_TRUSTED to indicate that a key either comes from a trusted source
or had a cryptographic signature chain that led back to a trusted key the
kernel already possessed.
Add KEY_FLAGS_TRUSTED_ONLY to indicate that a keyring will only accept links to
keys marked with KEY_FLAGS_TRUSTED.
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index f7cdea2..9b6f6e0 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -1183,6 +1183,10 @@
key_check(keyring);
key_check(key);
+ if (test_bit(KEY_FLAG_TRUSTED_ONLY, &keyring->flags) &&
+ !test_bit(KEY_FLAG_TRUSTED, &key->flags))
+ return -EPERM;
+
ret = __key_link_begin(keyring, &key->index_key, &edit);
if (ret == 0) {
kdebug("begun {%d,%d}", keyring->serial, atomic_read(&keyring->usage));