[PATCH v3 12/14] integrity: Do not allow mok keyring updates following init

[Eric Snowberg]

The mok keyring is setup during init.  No additional keys should be allowed
to be added afterwards.  Leave the permission as read only.

Signed-off-by: Eric Snowberg <eric.snowberg@xxxxxxxxxx>
---
v2: Initial version
v3: Unmodified from v2
---
 security/integrity/digsig.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
index ec94d564c68a..0601ef458e03 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -145,7 +145,8 @@ int __init integrity_init_keyring(const unsigned int id)
 	else
 		restriction->check = restrict_link_to_ima;
 
-	perm |= KEY_USR_WRITE;
+	if (id != INTEGRITY_KEYRING_MOK)
+		perm |= KEY_USR_WRITE;
 
 out:
 	return __integrity_init_keyring(id, perm, restriction);
-- 
2.18.4