From 4d99750106adbaecee587232f2589f65170d5ce4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?= <mic@linux.microsoft.com>
Date: Tue, 22 Mar 2022 12:13:23 +0100
Subject: [PATCH] certs: Explain the rationale to call panic()
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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/20220322111323.542184-2-mic@digikod.net
Link: https://lore.kernel.org/r/YjeW2r6Wv55Du0bJ@iki.fi
Suggested-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
certs/blacklist.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/certs/blacklist.c b/certs/blacklist.c
index 486ce0dd8e9cb..25094ea736007 100644
--- 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)
{
--
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