diff --git a/crypto/asymmetric_keys/Kconfig b/crypto/asymmetric_keys/Kconfig
index ca41be5..4870f28 100644
--- a/crypto/asymmetric_keys/Kconfig
+++ b/crypto/asymmetric_keys/Kconfig
@@ -22,7 +22,6 @@
 
 config PUBLIC_KEY_ALGO_RSA
 	tristate "RSA public-key algorithm"
-	select MPILIB_EXTRA
 	select MPILIB
 	help
 	  This option enables support for the RSA algorithm (PKCS#1, RFC3447).
diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index 59b217a..7dd55b7 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -284,6 +284,8 @@
 						desc, "", 0, idmap);
 		mutex_unlock(&idmap->idmap_mutex);
 	}
+	if (!IS_ERR(rkey))
+		set_bit(KEY_FLAG_ROOT_CAN_INVAL, &rkey->flags);
 
 	kfree(desc);
 	return rkey;
diff --git a/include/linux/key.h b/include/linux/key.h
index 65316f7..e1d4715 100644
--- a/include/linux/key.h
+++ b/include/linux/key.h
@@ -171,6 +171,7 @@
 #define KEY_FLAG_TRUSTED	8	/* set if key is trusted */
 #define KEY_FLAG_TRUSTED_ONLY	9	/* set if keyring only accepts links to trusted keys */
 #define KEY_FLAG_BUILTIN	10	/* set if key is builtin */
+#define KEY_FLAG_ROOT_CAN_INVAL	11	/* set if key can be invalidated by root without permission */
 
 	/* the key type and key description string
 	 * - the desc is used to match a key against search criteria
diff --git a/lib/Kconfig b/lib/Kconfig
index 334f772..a8a775730 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -451,7 +451,8 @@
 
 config SIGNATURE
 	tristate
-	depends on KEYS && CRYPTO
+	depends on KEYS
+	select CRYPTO
 	select CRYPTO_SHA1
 	select MPILIB
 	help
diff --git a/net/dns_resolver/dns_query.c b/net/dns_resolver/dns_query.c
index 9acec61f..9a32f55 100644
--- a/net/dns_resolver/dns_query.c
+++ b/net/dns_resolver/dns_query.c
@@ -129,6 +129,7 @@
 	}
 
 	down_read(&rkey->sem);
+	set_bit(KEY_FLAG_ROOT_CAN_INVAL, &rkey->flags);
 	rkey->perm |= KEY_USR_VIEW;
 
 	ret = key_validate(rkey);
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 8a8c233..e26f860 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -406,12 +406,25 @@
 	key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
 	if (IS_ERR(key_ref)) {
 		ret = PTR_ERR(key_ref);
+
+		/* Root is permitted to invalidate certain special keys */
+		if (capable(CAP_SYS_ADMIN)) {
+			key_ref = lookup_user_key(id, 0, 0);
+			if (IS_ERR(key_ref))
+				goto error;
+			if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
+				     &key_ref_to_ptr(key_ref)->flags))
+				goto invalidate;
+			goto error_put;
+		}
+
 		goto error;
 	}
 
+invalidate:
 	key_invalidate(key_ref_to_ptr(key_ref));
 	ret = 0;
-
+error_put:
 	key_ref_put(key_ref);
 error:
 	kleave(" = %ld", ret);