// SPDX-License-Identifier: GPL-2.0-only#include <linux/kernel.h>#include <linux/init.h>#include <linux/prandom.h>#include <linux/debugfs.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> /* * The should_fail() functions use prandom instead of the normal Linux RNG * since they don't need cryptographically secure random numbers. */static DEFINE_PER_CPU(struct rnd_state, fault_rnd_state); static u32 fault_prandom_u32_below_100(void){	struct rnd_state *state;	u32 res; 	state = &get_cpu_var(fault_rnd_state);	res = prandom_u32_state(state);	put_cpu_var(fault_rnd_state); 	return res % 100;} /* * 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;	} 	prandom_init_once(&fault_rnd_state); 	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 <= fault_prandom_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; 	prandom_init_once(&fault_rnd_state); 	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){	prandom_init_once(&fault_rnd_state); 	config_group_init_type_name(&config->group, name, &fault_config_type);}EXPORT_SYMBOL_GPL(fault_config_init); #endif /* CONFIG_FAULT_INJECTION_CONFIGFS */