1 files changed, 437 insertions, 0 deletions
diff --git a/lib/fault-inject.c b/lib/fault-inject.c
new file mode 100644
index 0000000000..d608f9b48c
--- /dev/null
+++ b/lib/fault-inject.c
@@ -0,0 +1,437 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/random.h>
+#include <linux/sched.h>
+#include <linux/stat.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/export.h>
+#include <linux/interrupt.h>
+#include <linux/stacktrace.h>
+#include <linux/fault-inject.h>
+
+/*
+ * setup_fault_attr() is a helper function for various __setup handlers, so it
+ * returns 0 on error, because that is what __setup handlers do.
+ */
+int setup_fault_attr(struct fault_attr *attr, char *str)
+{
+	unsigned long probability;
+	unsigned long interval;
+	int times;
+	int space;
+
+	/* "<interval>,<probability>,<space>,<times>" */
+	if (sscanf(str, "%lu,%lu,%d,%d",
+			&interval, &probability, &space, &times) < 4) {
+		printk(KERN_WARNING
+			"FAULT_INJECTION: failed to parse arguments\n");
+		return 0;
+	}
+
+	attr->probability = probability;
+	attr->interval = interval;
+	atomic_set(&attr->times, times);
+	atomic_set(&attr->space, space);
+
+	return 1;
+}
+EXPORT_SYMBOL_GPL(setup_fault_attr);
+
+static void fail_dump(struct fault_attr *attr)
+{
+	if (attr->verbose > 0 && __ratelimit(&attr->ratelimit_state)) {
+		printk(KERN_NOTICE "FAULT_INJECTION: forcing a failure.\n"
+		       "name %pd, interval %lu, probability %lu, "
+		       "space %d, times %d\n", attr->dname,
+		       attr->interval, attr->probability,
+		       atomic_read(&attr->space),
+		       atomic_read(&attr->times));
+		if (attr->verbose > 1)
+			dump_stack();
+	}
+}
+
+#define atomic_dec_not_zero(v)		atomic_add_unless((v), -1, 0)
+
+static bool fail_task(struct fault_attr *attr, struct task_struct *task)
+{
+	return in_task() && task->make_it_fail;
+}
+
+#define MAX_STACK_TRACE_DEPTH 32
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+
+static bool fail_stacktrace(struct fault_attr *attr)
+{
+	int depth = attr->stacktrace_depth;
+	unsigned long entries[MAX_STACK_TRACE_DEPTH];
+	int n, nr_entries;
+	bool found = (attr->require_start == 0 && attr->require_end == ULONG_MAX);
+
+	if (depth == 0 || (found && !attr->reject_start && !attr->reject_end))
+		return found;
+
+	nr_entries = stack_trace_save(entries, depth, 1);
+	for (n = 0; n < nr_entries; n++) {
+		if (attr->reject_start <= entries[n] &&
+			       entries[n] < attr->reject_end)
+			return false;
+		if (attr->require_start <= entries[n] &&
+			       entries[n] < attr->require_end)
+			found = true;
+	}
+	return found;
+}
+
+#else
+
+static inline bool fail_stacktrace(struct fault_attr *attr)
+{
+	return true;
+}
+
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
+/*
+ * This code is stolen from failmalloc-1.0
+ * http://www.nongnu.org/failmalloc/
+ */
+
+bool should_fail_ex(struct fault_attr *attr, ssize_t size, int flags)
+{
+	bool stack_checked = false;
+
+	if (in_task()) {
+		unsigned int fail_nth = READ_ONCE(current->fail_nth);
+
+		if (fail_nth) {
+			if (!fail_stacktrace(attr))
+				return false;
+
+			stack_checked = true;
+			fail_nth--;
+			WRITE_ONCE(current->fail_nth, fail_nth);
+			if (!fail_nth)
+				goto fail;
+
+			return false;
+		}
+	}
+
+	/* No need to check any other properties if the probability is 0 */
+	if (attr->probability == 0)
+		return false;
+
+	if (attr->task_filter && !fail_task(attr, current))
+		return false;
+
+	if (atomic_read(&attr->times) == 0)
+		return false;
+
+	if (!stack_checked && !fail_stacktrace(attr))
+		return false;
+
+	if (atomic_read(&attr->space) > size) {
+		atomic_sub(size, &attr->space);
+		return false;
+	}
+
+	if (attr->interval > 1) {
+		attr->count++;
+		if (attr->count % attr->interval)
+			return false;
+	}
+
+	if (attr->probability <= get_random_u32_below(100))
+		return false;
+
+fail:
+	if (!(flags & FAULT_NOWARN))
+		fail_dump(attr);
+
+	if (atomic_read(&attr->times) != -1)
+		atomic_dec_not_zero(&attr->times);
+
+	return true;
+}
+
+bool should_fail(struct fault_attr *attr, ssize_t size)
+{
+	return should_fail_ex(attr, size, 0);
+}
+EXPORT_SYMBOL_GPL(should_fail);
+
+#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
+
+static int debugfs_ul_set(void *data, u64 val)
+{
+	*(unsigned long *)data = val;
+	return 0;
+}
+
+static int debugfs_ul_get(void *data, u64 *val)
+{
+	*val = *(unsigned long *)data;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_ul, debugfs_ul_get, debugfs_ul_set, "%llu\n");
+
+static void debugfs_create_ul(const char *name, umode_t mode,
+			      struct dentry *parent, unsigned long *value)
+{
+	debugfs_create_file(name, mode, parent, value, &fops_ul);
+}
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+
+static int debugfs_stacktrace_depth_set(void *data, u64 val)
+{
+	*(unsigned long *)data =
+		min_t(unsigned long, val, MAX_STACK_TRACE_DEPTH);
+
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fops_stacktrace_depth, debugfs_ul_get,
+			debugfs_stacktrace_depth_set, "%llu\n");
+
+static void debugfs_create_stacktrace_depth(const char *name, umode_t mode,
+					    struct dentry *parent,
+					    unsigned long *value)
+{
+	debugfs_create_file(name, mode, parent, value, &fops_stacktrace_depth);
+}
+
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
+struct dentry *fault_create_debugfs_attr(const char *name,
+			struct dentry *parent, struct fault_attr *attr)
+{
+	umode_t mode = S_IFREG | S_IRUSR | S_IWUSR;
+	struct dentry *dir;
+
+	dir = debugfs_create_dir(name, parent);
+	if (IS_ERR(dir))
+		return dir;
+
+	debugfs_create_ul("probability", mode, dir, &attr->probability);
+	debugfs_create_ul("interval", mode, dir, &attr->interval);
+	debugfs_create_atomic_t("times", mode, dir, &attr->times);
+	debugfs_create_atomic_t("space", mode, dir, &attr->space);
+	debugfs_create_ul("verbose", mode, dir, &attr->verbose);
+	debugfs_create_u32("verbose_ratelimit_interval_ms", mode, dir,
+			   &attr->ratelimit_state.interval);
+	debugfs_create_u32("verbose_ratelimit_burst", mode, dir,
+			   &attr->ratelimit_state.burst);
+	debugfs_create_bool("task-filter", mode, dir, &attr->task_filter);
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+	debugfs_create_stacktrace_depth("stacktrace-depth", mode, dir,
+					&attr->stacktrace_depth);
+	debugfs_create_xul("require-start", mode, dir, &attr->require_start);
+	debugfs_create_xul("require-end", mode, dir, &attr->require_end);
+	debugfs_create_xul("reject-start", mode, dir, &attr->reject_start);
+	debugfs_create_xul("reject-end", mode, dir, &attr->reject_end);
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
+	attr->dname = dget(dir);
+	return dir;
+}
+EXPORT_SYMBOL_GPL(fault_create_debugfs_attr);
+
+#endif /* CONFIG_FAULT_INJECTION_DEBUG_FS */
+
+#ifdef CONFIG_FAULT_INJECTION_CONFIGFS
+
+/* These configfs attribute utilities are copied from drivers/block/null_blk/main.c */
+
+static ssize_t fault_uint_attr_show(unsigned int val, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%u\n", val);
+}
+
+static ssize_t fault_ulong_attr_show(unsigned long val, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%lu\n", val);
+}
+
+static ssize_t fault_bool_attr_show(bool val, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%u\n", val);
+}
+
+static ssize_t fault_atomic_t_attr_show(atomic_t val, char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%d\n", atomic_read(&val));
+}
+
+static ssize_t fault_uint_attr_store(unsigned int *val, const char *page, size_t count)
+{
+	unsigned int tmp;
+	int result;
+
+	result = kstrtouint(page, 0, &tmp);
+	if (result < 0)
+		return result;
+
+	*val = tmp;
+	return count;
+}
+
+static ssize_t fault_ulong_attr_store(unsigned long *val, const char *page, size_t count)
+{
+	int result;
+	unsigned long tmp;
+
+	result = kstrtoul(page, 0, &tmp);
+	if (result < 0)
+		return result;
+
+	*val = tmp;
+	return count;
+}
+
+static ssize_t fault_bool_attr_store(bool *val, const char *page, size_t count)
+{
+	bool tmp;
+	int result;
+
+	result = kstrtobool(page, &tmp);
+	if (result < 0)
+		return result;
+
+	*val = tmp;
+	return count;
+}
+
+static ssize_t fault_atomic_t_attr_store(atomic_t *val, const char *page, size_t count)
+{
+	int tmp;
+	int result;
+
+	result = kstrtoint(page, 0, &tmp);
+	if (result < 0)
+		return result;
+
+	atomic_set(val, tmp);
+	return count;
+}
+
+#define CONFIGFS_ATTR_NAMED(_pfx, _name, _attr_name)	\
+static struct configfs_attribute _pfx##attr_##_name = {	\
+	.ca_name	= _attr_name,			\
+	.ca_mode	= 0644,				\
+	.ca_owner	= THIS_MODULE,			\
+	.show		= _pfx##_name##_show,		\
+	.store		= _pfx##_name##_store,		\
+}
+
+static struct fault_config *to_fault_config(struct config_item *item)
+{
+	return container_of(to_config_group(item), struct fault_config, group);
+}
+
+#define FAULT_CONFIGFS_ATTR_NAMED(NAME, ATTR_NAME, MEMBER, TYPE)				\
+static ssize_t fault_##NAME##_show(struct config_item *item, char *page)			\
+{												\
+	return fault_##TYPE##_attr_show(to_fault_config(item)->attr.MEMBER, page);		\
+}												\
+static ssize_t fault_##NAME##_store(struct config_item *item, const char *page, size_t count)	\
+{												\
+	struct fault_config *config = to_fault_config(item);					\
+	return fault_##TYPE##_attr_store(&config->attr.MEMBER, page, count);			\
+}												\
+CONFIGFS_ATTR_NAMED(fault_, NAME, ATTR_NAME)
+
+#define FAULT_CONFIGFS_ATTR(NAME, TYPE)	\
+	FAULT_CONFIGFS_ATTR_NAMED(NAME, __stringify(NAME), NAME, TYPE)
+
+FAULT_CONFIGFS_ATTR(probability, ulong);
+FAULT_CONFIGFS_ATTR(interval, ulong);
+FAULT_CONFIGFS_ATTR(times, atomic_t);
+FAULT_CONFIGFS_ATTR(space, atomic_t);
+FAULT_CONFIGFS_ATTR(verbose, ulong);
+FAULT_CONFIGFS_ATTR_NAMED(ratelimit_interval, "verbose_ratelimit_interval_ms",
+		ratelimit_state.interval, uint);
+FAULT_CONFIGFS_ATTR_NAMED(ratelimit_burst, "verbose_ratelimit_burst",
+		ratelimit_state.burst, uint);
+FAULT_CONFIGFS_ATTR_NAMED(task_filter, "task-filter", task_filter, bool);
+
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+
+static ssize_t fault_stacktrace_depth_show(struct config_item *item, char *page)
+{
+	return fault_ulong_attr_show(to_fault_config(item)->attr.stacktrace_depth, page);
+}
+
+static ssize_t fault_stacktrace_depth_store(struct config_item *item, const char *page,
+		size_t count)
+{
+	int result;
+	unsigned long tmp;
+
+	result = kstrtoul(page, 0, &tmp);
+	if (result < 0)
+		return result;
+
+	to_fault_config(item)->attr.stacktrace_depth =
+		min_t(unsigned long, tmp, MAX_STACK_TRACE_DEPTH);
+
+	return count;
+}
+
+CONFIGFS_ATTR_NAMED(fault_, stacktrace_depth, "stacktrace-depth");
+
+static ssize_t fault_xul_attr_show(unsigned long val, char *page)
+{
+	return snprintf(page, PAGE_SIZE,
+			sizeof(val) == sizeof(u32) ? "0x%08lx\n" : "0x%016lx\n", val);
+}
+
+static ssize_t fault_xul_attr_store(unsigned long *val, const char *page, size_t count)
+{
+	return fault_ulong_attr_store(val, page, count);
+}
+
+FAULT_CONFIGFS_ATTR_NAMED(require_start, "require-start", require_start, xul);
+FAULT_CONFIGFS_ATTR_NAMED(require_end, "require-end", require_end, xul);
+FAULT_CONFIGFS_ATTR_NAMED(reject_start, "reject-start", reject_start, xul);
+FAULT_CONFIGFS_ATTR_NAMED(reject_end, "reject-end", reject_end, xul);
+
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+
+static struct configfs_attribute *fault_config_attrs[] = {
+	&fault_attr_probability,
+	&fault_attr_interval,
+	&fault_attr_times,
+	&fault_attr_space,
+	&fault_attr_verbose,
+	&fault_attr_ratelimit_interval,
+	&fault_attr_ratelimit_burst,
+	&fault_attr_task_filter,
+#ifdef CONFIG_FAULT_INJECTION_STACKTRACE_FILTER
+	&fault_attr_stacktrace_depth,
+	&fault_attr_require_start,
+	&fault_attr_require_end,
+	&fault_attr_reject_start,
+	&fault_attr_reject_end,
+#endif /* CONFIG_FAULT_INJECTION_STACKTRACE_FILTER */
+	NULL,
+};
+
+static const struct config_item_type fault_config_type = {
+	.ct_attrs	= fault_config_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+void fault_config_init(struct fault_config *config, const char *name)
+{
+	config_group_init_type_name(&config->group, name, &fault_config_type);
+}
+EXPORT_SYMBOL_GPL(fault_config_init);
+
+#endif /* CONFIG_FAULT_INJECTION_CONFIGFS */