From e1f556835f4fdc766bbd0d4a44f3bbeb64671d1a Mon Sep 17 00:00:00 2001
From: Mimi Zohar <zohar@linux.ibm.com>
Date: Mon, 12 Jul 2021 17:24:03 +0800
Subject: [PATCH] module: limit enabling module.sig_enforce
stable inclusion
from linux-4.19.196
commit ff660863628fb144badcb3395cde7821c82c13a6
CVE: CVE-2021-35039
--------------------------------
[ 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@linux.ibm.com>
Tested-by: Mimi Zohar <zohar@linux.ibm.com>
Tested-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Jessica Yu <jeyu@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
kernel/module.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/kernel/module.c b/kernel/module.c
index ad4c1d7b7a95..82c83cbf6ce6 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -268,9 +268,18 @@ 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.
--
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