[PATCH 01/15] taint: add module firmware crash taint support

Luis Chamberlain
2020-05-09T04:36:08Z

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