# \[PATCH v4 02/12\] integrity: Do not allow mok keyring updates following init

- From: Eric Snowberg \<eric.snowberg@oracle.com\>
- Date: 2021-08-19 00:22:47 
- List: linux-integrity
- Page: https://ratatoskr.run/linux-integrity/2021/08/1482273
- Thread: https://ratatoskr.run/keyrings/2021/08/1482265/t.md

```text
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@oracle.com>
---
v2: Initial version
v4: 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 e07334504ef1..5cad38e6f56a 100644
--- a/security/integrity/digsig.c
+++ b/security/integrity/digsig.c
@@ -140,7 +140,8 @@ int __init integrity_init_keyring(const unsigned int id)
 		return -ENOMEM;
 
 	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

```