linux-kernel - [PATCH] module: Issue warnings when tainting kernel

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Message-ID: <20160412064737.GA5549@fm.suse.cz>
Date:	Tue, 12 Apr 2016 08:50:25 +0200
From:	Libor Pechacek <lpechacek@...e.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] module: Issue warnings when tainting kernel

While most of the locations where a kernel taint bit is set are accompanied
with a warning message, there are two which set their bits silently.  If
the tainting module gets unloaded later on, it is almost impossible to tell
what was the reason for setting the flag.

Signed-off-by: Libor Pechacek <lpechacek@...e.com>
---
 kernel/module.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/module.c b/kernel/module.c
index 041200ca4a2d..e2d83d77a0e9 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2812,8 +2812,12 @@ static int check_modinfo(struct module *mod, struct load_info *info, int flags)
 		return -ENOEXEC;
 	}
 
-	if (!get_modinfo(info, "intree"))
+	if (!get_modinfo(info, "intree")) {
+		if (!test_taint(TAINT_OOT_MODULE))
+			pr_warn("%s: loading out-of-tree module taints kernel.\n",
+				mod->name);
 		add_taint_module(mod, TAINT_OOT_MODULE, LOCKDEP_STILL_OK);
+	}
 
 	if (get_modinfo(info, "staging")) {
 		add_taint_module(mod, TAINT_CRAP, LOCKDEP_STILL_OK);
@@ -2978,6 +2982,8 @@ static int move_module(struct module *mod, struct load_info *info)
 
 static int check_module_license_and_versions(struct module *mod)
 {
+	int prev_taint = test_taint(TAINT_PROPRIETARY_MODULE);
+
 	/*
 	 * ndiswrapper is under GPL by itself, but loads proprietary modules.
 	 * Don't use add_taint_module(), as it would prevent ndiswrapper from
@@ -2996,6 +3002,9 @@ static int check_module_license_and_versions(struct module *mod)
 		add_taint_module(mod, TAINT_PROPRIETARY_MODULE,
 				 LOCKDEP_NOW_UNRELIABLE);
 
+	if (!prev_taint && test_taint(TAINT_PROPRIETARY_MODULE))
+		pr_warn("%s: module license taints kernel.\n", mod->name);
+
 #ifdef CONFIG_MODVERSIONS
 	if ((mod->num_syms && !mod->crcs)
 	    || (mod->num_gpl_syms && !mod->gpl_crcs)
-- 
1.7.12.4