linux-kernel - [PATCH] lockdown: Only log restrictions once

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Message-ID: <3641397.L58v44csPz@daniel-desktop3>
Date: Wed, 19 Nov 2025 08:22:40 -0500
From: Daniel Tang <danielzgtg.opensource@...il.com>
To: linux-security-module@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, Nathan Lynch <nathanl@...ux.ibm.com>,
 Paul Moore <paul@...l-moore.com>, Matthew Garrett <mjg59@...gle.com>,
 Kees Cook <keescook@...omium.org>, David Howells <dhowells@...hat.com>,
 James Morris <jmorris@...ei.org>
Subject: [PATCH] lockdown: Only log restrictions once

KDE's lockscreen causes systemd-logind to spam dmesg about hibernation.
systemd declined to cache /sys/power/state due to runtime changeability.

Link: https://github.com/systemd/systemd/pull/39802
Signed-off-by: Daniel Tang <danielzgtg.opensource@...il.com>
---
 security/lockdown/lockdown.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index cf83afa1d879..4ced8c76dc6b 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -62,9 +62,11 @@ static int lockdown_is_locked_down(enum lockdown_reason what)
 		 "Invalid lockdown reason"))
 		return -EPERM;
 
+	static volatile unsigned long lockdown_reasons_seen;
+	static_assert(ARRAY_SIZE(lockdown_reasons) < sizeof(lockdown_reasons_seen) * 8);
 	if (kernel_locked_down >= what) {
-		if (lockdown_reasons[what])
-			pr_notice_ratelimited("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n",
+		if (lockdown_reasons[what] && !test_and_set_bit(what, &lockdown_reasons_seen))
+			pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n",
 				  current->comm, lockdown_reasons[what]);
 		return -EPERM;
 	}
-- 
2.51.0