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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Linux Kernel Dump Test Module for testing kernel crashes conditions:4 * induces system failures at predefined crashpoints and under predefined5 * operational conditions in order to evaluate the reliability of kernel6 * sanity checking and crash dumps obtained using different dumping7 * solutions.8 *9 * Copyright (C) IBM Corporation, 200610 *11 * Author: Ankita Garg <ankita@in.ibm.com>12 *13 * It is adapted from the Linux Kernel Dump Test Tool by14 * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>15 *16 * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>17 *18 * See Documentation/fault-injection/provoke-crashes.rst for instructions19 */20#include "lkdtm.h"21#include <linux/fs.h>22#include <linux/module.h>23#include <linux/buffer_head.h>24#include <linux/kprobes.h>25#include <linux/list.h>26#include <linux/init.h>27#include <linux/slab.h>28#include <linux/debugfs.h>29#include <linux/utsname.h>30 31#define DEFAULT_COUNT 1032 33static int lkdtm_debugfs_open(struct inode *inode, struct file *file);34static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,35 size_t count, loff_t *off);36static ssize_t direct_entry(struct file *f, const char __user *user_buf,37 size_t count, loff_t *off);38 39#ifdef CONFIG_KPROBES40static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);41static ssize_t lkdtm_debugfs_entry(struct file *f,42 const char __user *user_buf,43 size_t count, loff_t *off);44# define CRASHPOINT_KPROBE(_symbol) \45 .kprobe = { \46 .symbol_name = (_symbol), \47 .pre_handler = lkdtm_kprobe_handler, \48 },49# define CRASHPOINT_WRITE(_symbol) \50 (_symbol) ? lkdtm_debugfs_entry : direct_entry51#else52# define CRASHPOINT_KPROBE(_symbol)53# define CRASHPOINT_WRITE(_symbol) direct_entry54#endif55 56/* Crash points */57struct crashpoint {58 const char *name;59 const struct file_operations fops;60 struct kprobe kprobe;61};62 63#define CRASHPOINT(_name, _symbol) \64 { \65 .name = _name, \66 .fops = { \67 .read = lkdtm_debugfs_read, \68 .llseek = generic_file_llseek, \69 .open = lkdtm_debugfs_open, \70 .write = CRASHPOINT_WRITE(_symbol) \71 }, \72 CRASHPOINT_KPROBE(_symbol) \73 }74 75/* Define the possible places where we can trigger a crash point. */76static struct crashpoint crashpoints[] = {77 CRASHPOINT("DIRECT", NULL),78#ifdef CONFIG_KPROBES79 CRASHPOINT("INT_HARDWARE_ENTRY", "do_IRQ"),80 CRASHPOINT("INT_HW_IRQ_EN", "handle_irq_event"),81 CRASHPOINT("INT_TASKLET_ENTRY", "tasklet_action"),82 CRASHPOINT("FS_SUBMIT_BH", "submit_bh"),83 CRASHPOINT("MEM_SWAPOUT", "shrink_inactive_list"),84 CRASHPOINT("TIMERADD", "hrtimer_start"),85 CRASHPOINT("SCSI_QUEUE_RQ", "scsi_queue_rq"),86#endif87};88 89/* List of possible types for crashes that can be triggered. */90static const struct crashtype_category *crashtype_categories[] = {91 &bugs_crashtypes,92 &heap_crashtypes,93 &perms_crashtypes,94 &refcount_crashtypes,95 &usercopy_crashtypes,96 &stackleak_crashtypes,97 &cfi_crashtypes,98 &fortify_crashtypes,99#ifdef CONFIG_PPC_64S_HASH_MMU100 &powerpc_crashtypes,101#endif102};103 104/* Global kprobe entry and crashtype. */105static struct kprobe *lkdtm_kprobe;106static struct crashpoint *lkdtm_crashpoint;107static const struct crashtype *lkdtm_crashtype;108 109/* Module parameters */110static int recur_count = -1;111module_param(recur_count, int, 0644);112MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");113 114static char* cpoint_name;115module_param(cpoint_name, charp, 0444);116MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");117 118static char* cpoint_type;119module_param(cpoint_type, charp, 0444);120MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\121 "hitting the crash point");122 123static int cpoint_count = DEFAULT_COUNT;124module_param(cpoint_count, int, 0644);125MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\126 "crash point is to be hit to trigger action");127 128/*129 * For test debug reporting when CI systems provide terse summaries.130 * TODO: Remove this once reasonable reporting exists in most CI systems:131 * https://lore.kernel.org/lkml/CAHk-=wiFvfkoFixTapvvyPMN9pq5G-+Dys2eSyBa1vzDGAO5+A@mail.gmail.com132 */133char *lkdtm_kernel_info;134 135/* Return the crashtype number or NULL if the name is invalid */136static const struct crashtype *find_crashtype(const char *name)137{138 int cat, idx;139 140 for (cat = 0; cat < ARRAY_SIZE(crashtype_categories); cat++) {141 for (idx = 0; idx < crashtype_categories[cat]->len; idx++) {142 struct crashtype *crashtype;143 144 crashtype = &crashtype_categories[cat]->crashtypes[idx];145 if (!strcmp(name, crashtype->name))146 return crashtype;147 }148 }149 150 return NULL;151}152 153/*154 * This is forced noinline just so it distinctly shows up in the stackdump155 * which makes validation of expected lkdtm crashes easier.156 *157 * NOTE: having a valid return value helps prevent the compiler from doing158 * tail call optimizations and taking this out of the stack trace.159 */160static noinline int lkdtm_do_action(const struct crashtype *crashtype)161{162 if (WARN_ON(!crashtype || !crashtype->func))163 return -EINVAL;164 crashtype->func();165 166 return 0;167}168 169static int lkdtm_register_cpoint(struct crashpoint *crashpoint,170 const struct crashtype *crashtype)171{172 int ret;173 174 /* If this doesn't have a symbol, just call immediately. */175 if (!crashpoint->kprobe.symbol_name)176 return lkdtm_do_action(crashtype);177 178 if (lkdtm_kprobe != NULL)179 unregister_kprobe(lkdtm_kprobe);180 181 lkdtm_crashpoint = crashpoint;182 lkdtm_crashtype = crashtype;183 lkdtm_kprobe = &crashpoint->kprobe;184 ret = register_kprobe(lkdtm_kprobe);185 if (ret < 0) {186 pr_info("Couldn't register kprobe %s\n",187 crashpoint->kprobe.symbol_name);188 lkdtm_kprobe = NULL;189 lkdtm_crashpoint = NULL;190 lkdtm_crashtype = NULL;191 }192 193 return ret;194}195 196#ifdef CONFIG_KPROBES197/* Global crash counter and spinlock. */198static int crash_count = DEFAULT_COUNT;199static DEFINE_SPINLOCK(crash_count_lock);200 201/* Called by kprobe entry points. */202static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)203{204 unsigned long flags;205 bool do_it = false;206 207 if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))208 return 0;209 210 spin_lock_irqsave(&crash_count_lock, flags);211 crash_count--;212 pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",213 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);214 215 if (crash_count == 0) {216 do_it = true;217 crash_count = cpoint_count;218 }219 spin_unlock_irqrestore(&crash_count_lock, flags);220 221 if (do_it)222 return lkdtm_do_action(lkdtm_crashtype);223 224 return 0;225}226 227static ssize_t lkdtm_debugfs_entry(struct file *f,228 const char __user *user_buf,229 size_t count, loff_t *off)230{231 struct crashpoint *crashpoint = file_inode(f)->i_private;232 const struct crashtype *crashtype = NULL;233 char *buf;234 int err;235 236 if (count >= PAGE_SIZE)237 return -EINVAL;238 239 buf = (char *)__get_free_page(GFP_KERNEL);240 if (!buf)241 return -ENOMEM;242 if (copy_from_user(buf, user_buf, count)) {243 free_page((unsigned long) buf);244 return -EFAULT;245 }246 /* NULL-terminate and remove enter */247 buf[count] = '\0';248 strim(buf);249 250 crashtype = find_crashtype(buf);251 free_page((unsigned long)buf);252 253 if (!crashtype)254 return -EINVAL;255 256 err = lkdtm_register_cpoint(crashpoint, crashtype);257 if (err < 0)258 return err;259 260 *off += count;261 262 return count;263}264#endif265 266/* Generic read callback that just prints out the available crash types */267static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,268 size_t count, loff_t *off)269{270 int n, cat, idx;271 ssize_t out;272 char *buf;273 274 buf = (char *)__get_free_page(GFP_KERNEL);275 if (buf == NULL)276 return -ENOMEM;277 278 n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");279 280 for (cat = 0; cat < ARRAY_SIZE(crashtype_categories); cat++) {281 for (idx = 0; idx < crashtype_categories[cat]->len; idx++) {282 struct crashtype *crashtype;283 284 crashtype = &crashtype_categories[cat]->crashtypes[idx];285 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",286 crashtype->name);287 }288 }289 buf[n] = '\0';290 291 out = simple_read_from_buffer(user_buf, count, off,292 buf, n);293 free_page((unsigned long) buf);294 295 return out;296}297 298static int lkdtm_debugfs_open(struct inode *inode, struct file *file)299{300 return 0;301}302 303/* Special entry to just crash directly. Available without KPROBEs */304static ssize_t direct_entry(struct file *f, const char __user *user_buf,305 size_t count, loff_t *off)306{307 const struct crashtype *crashtype;308 char *buf;309 int err;310 311 if (count >= PAGE_SIZE)312 return -EINVAL;313 if (count < 1)314 return -EINVAL;315 316 buf = (char *)__get_free_page(GFP_KERNEL);317 if (!buf)318 return -ENOMEM;319 if (copy_from_user(buf, user_buf, count)) {320 free_page((unsigned long) buf);321 return -EFAULT;322 }323 /* NULL-terminate and remove enter */324 buf[count] = '\0';325 strim(buf);326 327 crashtype = find_crashtype(buf);328 free_page((unsigned long) buf);329 if (!crashtype)330 return -EINVAL;331 332 pr_info("Performing direct entry %s\n", crashtype->name);333 err = lkdtm_do_action(crashtype);334 *off += count;335 336 if (err)337 return err;338 return count;339}340 341#ifndef MODULE342/*343 * To avoid needing to export parse_args(), just don't use this code344 * when LKDTM is built as a module.345 */346struct check_cmdline_args {347 const char *param;348 int value;349};350 351static int lkdtm_parse_one(char *param, char *val,352 const char *unused, void *arg)353{354 struct check_cmdline_args *args = arg;355 356 /* short circuit if we already found a value. */357 if (args->value != -ESRCH)358 return 0;359 if (strncmp(param, args->param, strlen(args->param)) == 0) {360 bool bool_result;361 int ret;362 363 ret = kstrtobool(val, &bool_result);364 if (ret == 0)365 args->value = bool_result;366 }367 return 0;368}369 370int lkdtm_check_bool_cmdline(const char *param)371{372 char *command_line;373 struct check_cmdline_args args = {374 .param = param,375 .value = -ESRCH,376 };377 378 command_line = kstrdup(saved_command_line, GFP_KERNEL);379 if (!command_line)380 return -ENOMEM;381 382 parse_args("Setting sysctl args", command_line,383 NULL, 0, -1, -1, &args, lkdtm_parse_one);384 385 kfree(command_line);386 387 return args.value;388}389#endif390 391static struct dentry *lkdtm_debugfs_root;392 393static int __init lkdtm_module_init(void)394{395 struct crashpoint *crashpoint = NULL;396 const struct crashtype *crashtype = NULL;397 int ret;398 int i;399 400 /* Neither or both of these need to be set */401 if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {402 pr_err("Need both cpoint_type and cpoint_name or neither\n");403 return -EINVAL;404 }405 406 if (cpoint_type) {407 crashtype = find_crashtype(cpoint_type);408 if (!crashtype) {409 pr_err("Unknown crashtype '%s'\n", cpoint_type);410 return -EINVAL;411 }412 }413 414 if (cpoint_name) {415 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {416 if (!strcmp(cpoint_name, crashpoints[i].name))417 crashpoint = &crashpoints[i];418 }419 420 /* Refuse unknown crashpoints. */421 if (!crashpoint) {422 pr_err("Invalid crashpoint %s\n", cpoint_name);423 return -EINVAL;424 }425 }426 427#ifdef CONFIG_KPROBES428 /* Set crash count. */429 crash_count = cpoint_count;430#endif431 432 /* Common initialization. */433 lkdtm_kernel_info = kasprintf(GFP_KERNEL, "kernel (%s %s)",434 init_uts_ns.name.release,435 init_uts_ns.name.machine);436 437 /* Handle test-specific initialization. */438 lkdtm_bugs_init(&recur_count);439 lkdtm_perms_init();440 lkdtm_usercopy_init();441 lkdtm_heap_init();442 443 /* Register debugfs interface */444 lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);445 446 /* Install debugfs trigger files. */447 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {448 struct crashpoint *cur = &crashpoints[i];449 450 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,451 &cur->fops);452 }453 454 /* Install crashpoint if one was selected. */455 if (crashpoint) {456 ret = lkdtm_register_cpoint(crashpoint, crashtype);457 if (ret < 0) {458 pr_info("Invalid crashpoint %s\n", crashpoint->name);459 goto out_err;460 }461 pr_info("Crash point %s of type %s registered\n",462 crashpoint->name, cpoint_type);463 } else {464 pr_info("No crash points registered, enable through debugfs\n");465 }466 467 return 0;468 469out_err:470 debugfs_remove_recursive(lkdtm_debugfs_root);471 return ret;472}473 474static void __exit lkdtm_module_exit(void)475{476 debugfs_remove_recursive(lkdtm_debugfs_root);477 478 /* Handle test-specific clean-up. */479 lkdtm_heap_exit();480 lkdtm_usercopy_exit();481 482 if (lkdtm_kprobe != NULL)483 unregister_kprobe(lkdtm_kprobe);484 485 kfree(lkdtm_kernel_info);486 487 pr_info("Crash point unregistered\n");488}489 490module_init(lkdtm_module_init);491module_exit(lkdtm_module_exit);492 493MODULE_LICENSE("GPL");494MODULE_DESCRIPTION("Kernel crash testing module");495