linux-kernel - [PATCH] module: Allow to disable modsign in kernel cmdline

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Date:   Tue, 28 Apr 2020 11:43:10 +0800
From:   Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
To:     jeyu@...nel.org
Cc:     linux-kernel@...r.kernel.org, tianjia.zhang@...ux.alibaba.com
Subject: [PATCH] module: Allow to disable modsign in kernel cmdline

This change allows to disable modsign completely at the beginning,
and turn off by set the kernel cmdline `no_modsig_enforce` when
CONFIG_MODULE_SIG_FORCE is enabled.

Yet another change allows to always show the current status of
modsign through `/sys/module/module/parameters/sig_enforce`.

Signed-off-by: Jia Zhang <zhang.jia@...ux.alibaba.com>
Signed-off-by: Tianjia Zhang <tianjia.zhang@...ux.alibaba.com>
---
 kernel/module.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index 646f1e2330d2..0e68e1286377 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -269,6 +269,14 @@ static void module_assert_mutex_or_preempt(void)
 
 static bool sig_enforce = IS_ENABLED(CONFIG_MODULE_SIG_FORCE);
 module_param(sig_enforce, bool_enable_only, 0644);
+#ifdef CONFIG_MODULE_SIG_FORCE
+static int __init set_no_modsig_enforce(char *str)
+{
+	sig_enforce = false;
+	return 1;
+}
+__setup("no_modsig_enforce", set_no_modsig_enforce);
+#endif /* !CONFIG_MODULE_SIG_FORCE */
 
 /*
  * Export sig_enforce kernel cmdline parameter to allow other subsystems rely
-- 
2.17.1