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From:   Luis Chamberlain <mcgrof@kernel.org>
To:     jeyu@kernel.org
Cc:     akpm@linux-foundation.org, arnd@arndb.de, rostedt@goodmis.org,
        mingo@redhat.com, aquini@redhat.com, cai@lca.pw, dyoung@redhat.com,
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        schlad@suse.de, andriy.shevchenko@linux.intel.com,
        keescook@chromium.org, daniel.vetter@ffwll.ch, will@kernel.org,
        mchehab+samsung@kernel.org, kvalo@codeaurora.org,
        davem@davemloft.net, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Luis Chamberlain <mcgrof@kernel.org>
Subject: [PATCH 01/15] taint: add module firmware crash taint support
Date:   Sat,  9 May 2020 04:35:38 +0000
Message-Id: <20200509043552.8745-2-mcgrof@kernel.org>
In-Reply-To: <20200509043552.8745-1-mcgrof@kernel.org>
References: <20200509043552.8745-1-mcgrof@kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Device driver firmware can crash, and sometimes, this can leave your
system in a state which makes the device or subsystem completely
useless. Detecting this by inspecting /proc/sys/kernel/tainted instead
of scraping some magical words from the kernel log, which is driver
specific, is much easier. So instead provide a helper which lets drivers
annotate this.

Once this happens, scrapers can easily look for modules taint flags
for a firmware crash. This will taint both the kernel and respective
calling module.

The new helper module_firmware_crashed() uses LOCKDEP_STILL_OK as this
fact should in no way shape or form affect lockdep. This taint is device
driver specific.

Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
---
 include/linux/kernel.h        |  3 ++-
 include/linux/module.h        | 13 +++++++++++++
 include/trace/events/module.h |  3 ++-
 kernel/module.c               |  5 +++--
 kernel/panic.c                |  1 +
 5 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/include/linux/kernel.h b/include/linux/kernel.h
index 04a5885cec1b..19e1541c82c7 100644
--- a/include/linux/kernel.h
+++ b/include/linux/kernel.h
@@ -601,7 +601,8 @@ extern enum system_states {
 #define TAINT_LIVEPATCH			15
 #define TAINT_AUX			16
 #define TAINT_RANDSTRUCT		17
-#define TAINT_FLAGS_COUNT		18
+#define TAINT_FIRMWARE_CRASH		18
+#define TAINT_FLAGS_COUNT		19
 
 struct taint_flag {
 	char c_true;	/* character printed when tainted */
diff --git a/include/linux/module.h b/include/linux/module.h
index 2c2e988bcf10..221200078180 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -697,6 +697,14 @@ static inline bool is_livepatch_module(struct module *mod)
 bool is_module_sig_enforced(void);
 void set_module_sig_enforced(void);
 
+void add_taint_module(struct module *mod, unsigned flag,
+		      enum lockdep_ok lockdep_ok);
+
+static inline void module_firmware_crashed(void)
+{
+	add_taint_module(THIS_MODULE, TAINT_FIRMWARE_CRASH, LOCKDEP_STILL_OK);
+}
+
 #else /* !CONFIG_MODULES... */
 
 static inline struct module *__module_address(unsigned long addr)
@@ -844,6 +852,11 @@ void *dereference_module_function_descriptor(struct module *mod, void *ptr)
 	return ptr;
 }
 
+static inline void module_firmware_crashed(void)
+{
+	add_taint(TAINT_FIRMWARE_CRASH, LOCKDEP_STILL_OK);
+}
+
 #endif /* CONFIG_MODULES */
 
 #ifdef CONFIG_SYSFS
diff --git a/include/trace/events/module.h b/include/trace/events/module.h
index 097485c73c01..b749ea25affd 100644
--- a/include/trace/events/module.h
+++ b/include/trace/events/module.h
@@ -26,7 +26,8 @@ struct module;
 	{ (1UL << TAINT_OOT_MODULE),		"O" },		\
 	{ (1UL << TAINT_FORCED_MODULE),		"F" },		\
 	{ (1UL << TAINT_CRAP),			"C" },		\
-	{ (1UL << TAINT_UNSIGNED_MODULE),	"E" })
+	{ (1UL << TAINT_UNSIGNED_MODULE),	"E" },		\
+	{ (1UL << TAINT_FIRMWARE_CRASH),	"Q" })
 
 TRACE_EVENT(module_load,
 
diff --git a/kernel/module.c b/kernel/module.c
index 80faaf2116dd..f98e8c25c6b4 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -325,12 +325,13 @@ static inline int strong_try_module_get(struct module *mod)
 		return -ENOENT;
 }
 
-static inline void add_taint_module(struct module *mod, unsigned flag,
-				    enum lockdep_ok lockdep_ok)
+void add_taint_module(struct module *mod, unsigned flag,
+		      enum lockdep_ok lockdep_ok)
 {
 	add_taint(flag, lockdep_ok);
 	set_bit(flag, &mod->taints);
 }
+EXPORT_SYMBOL_GPL(add_taint_module);
 
 /*
  * A thread that wants to hold a reference to a module only while it
diff --git a/kernel/panic.c b/kernel/panic.c
index ec6d7d788ce7..504fb926947e 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -384,6 +384,7 @@ const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
 	[ TAINT_LIVEPATCH ]		= { 'K', ' ', true },
 	[ TAINT_AUX ]			= { 'X', ' ', true },
 	[ TAINT_RANDSTRUCT ]		= { 'T', ' ', true },
+	[ TAINT_FIRMWARE_CRASH ]	= { 'Q', ' ', true },
 };
 
 /**
-- 
2.25.1