certs: Explain the rationale to call panic()

The blacklist_init() function calls panic() for memory allocation errors. This change documents the reason why we don't return -ENODEV. Link: https://lore.kernel.org/r/[email protected] Link: https://lore.kernel.org/r/[email protected] Suggested-by: Paul Moore <[email protected]> Reviewed-by: Paul Moore <[email protected]> Reviewed-by: Jarkko Sakkinen <[email protected]> Signed-off-by: Mickaël Salaün <[email protected]> Signed-off-by: Jarkko Sakkinen <[email protected]>
cilium · May 23, 2022 · 4d99750 · 4d99750
1 parent 6364d10
commit 4d99750
Showing 1 changed file with 9 additions and 0 deletions.
diff --git a/certs/blacklist.c b/certs/blacklist.c
@@ -307,6 +307,15 @@ static int restrict_link_for_blacklist(struct key *dest_keyring,
 
 /*
  * Initialise the blacklist
+ *
+ * The blacklist_init() function is registered as an initcall via
+ * device_initcall().  As a result if the blacklist_init() function fails for
+ * any reason the kernel continues to execute.  While cleanly returning -ENODEV
+ * could be acceptable for some non-critical kernel parts, if the blacklist
+ * keyring fails to load it defeats the certificate/key based deny list for
+ * signed modules.  If a critical piece of security functionality that users
+ * expect to be present fails to initialize, panic()ing is likely the right
+ * thing to do.
  */
 static int __init blacklist_init(void)
 {