[GIT PULL] Keys: Set 4 - Key ACLs for 5.3

[Mimi Zohar]

Hi Linus,

On Wed, 2019-07-10 at 18:59 -0700, Linus Torvalds wrote:
> Anyway, since it does seem like David is offline, I've just reverted
> this from my tree, and will be continuing my normal merge window pull
> requests (the other issues I have seen have fixes in their respective
> trees).

Sorry for the delay.  An exception is needed for loading builtin keys
"KEY_ALLOC_BUILT_IN" onto a keyring that is not writable by userspace.
 The following works, but probably is not how David would handle the
exception.

diff --git a/security/keys/key.c b/security/keys/key.c
index 519211a996e7..a99332c1e014 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -896,7 +896,7 @@ key_ref_t key_create_or_update(key_ref_t keyring_ref,
        /* if we're going to allocate a new key, we're going to have
         * to modify the keyring */
        ret = key_permission(keyring_ref, KEY_NEED_WRITE);
-       if (ret < 0) {
+       if (ret < 0 && !(flags & KEY_ALLOC_BUILT_IN)) {
                key_ref = ERR_PTR(ret);
                goto error_link_end;
        }

Mimi