linux-kernel - [PATCH 5.10 001/101] module: limit enabling module.sig

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Message-Id: <20210628142607.32218-2-sashal@kernel.org>
Date:   Mon, 28 Jun 2021 10:24:27 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Mimi Zohar <zohar@...ux.ibm.com>, Nayna Jain <nayna@...ux.ibm.com>,
        Jessica Yu <jeyu@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 001/101] module: limit enabling module.sig_enforce

From: Mimi Zohar <zohar@...ux.ibm.com>

[ Upstream commit 0c18f29aae7ce3dadd26d8ee3505d07cc982df75 ]

Irrespective as to whether CONFIG_MODULE_SIG is configured, specifying
"module.sig_enforce=1" on the boot command line sets "sig_enforce".
Only allow "sig_enforce" to be set when CONFIG_MODULE_SIG is configured.

This patch makes the presence of /sys/module/module/parameters/sig_enforce
dependent on CONFIG_MODULE_SIG=y.

Fixes: fda784e50aac ("module: export module signature enforcement status")
Reported-by: Nayna Jain <nayna@...ux.ibm.com>
Tested-by: Mimi Zohar <zohar@...ux.ibm.com>
Tested-by: Jessica Yu <jeyu@...nel.org>
Signed-off-by: Mimi Zohar <zohar@...ux.ibm.com>
Signed-off-by: Jessica Yu <jeyu@...nel.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/module.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 908d46abe165..185b2655bc20 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -272,9 +272,18 @@ static void module_assert_mutex_or_preempt(void)
 #endif
 }
 
+#ifdef CONFIG_MODULE_SIG
 static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
 module_param(sig_enforce, bool_enable_only, 0644);
 
+void set_module_sig_enforced(void)
+{
+	sig_enforce = true;
+}
+#else
+#define sig_enforce false
+#endif
+
 /*
  * Export sig_enforce kernel cmdline parameter to allow other subsystems rely
  * on that instead of directly to CONFIG_MODULE_SIG_FORCE config.
@@ -285,11 +294,6 @@ bool is_module_sig_enforced(void)
 }
 EXPORT_SYMBOL(is_module_sig_enforced);
 
-void set_module_sig_enforced(void)
-{
-	sig_enforce = true;
-}
-
 /* Block module loading/unloading? */
 int modules_disabled = 0;
 core_param(nomodule, modules_disabled, bint, 0);
-- 
2.30.2