linux-kernel - [PATCH 4.4 20/22] module: Issue warnings when tainting kernel

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Message-Id: <20180108125926.460779719@linuxfoundation.org>
Date:   Mon,  8 Jan 2018 13:59:47 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Libor Pechacek <lpechacek@...e.com>,
        Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH 4.4 20/22] module: Issue warnings when tainting kernel

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Libor Pechacek <lpechacek@...e.com>

commit 3205c36cf7d96024626f92d65f560035df1abcb2 upstream.

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>
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 kernel/module.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2888,8 +2888,12 @@ static int check_modinfo(struct module *
 		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);
@@ -3054,6 +3058,8 @@ static int move_module(struct module *mo
 
 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
@@ -3072,6 +3078,9 @@ static int check_module_license_and_vers
 		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)