// 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, ×) < 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) 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(struct fault_attr *attr, ssize_t size) { if (in_task()) { unsigned int fail_nth = READ_ONCE(current->fail_nth); if (fail_nth) { 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 (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 <= prandom_u32() % 100) return false; if (!fail_stacktrace(attr)) return false; fail: fail_dump(attr); if (atomic_read(&attr->times) != -1) atomic_dec_not_zero(&attr->times); return true; } 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_ul("require-start", mode, dir, &attr->require_start); debugfs_create_ul("require-end", mode, dir, &attr->require_end); debugfs_create_ul("reject-start", mode, dir, &attr->reject_start); debugfs_create_ul("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 */