drivers/misc/lkdtm/core.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Linux Kernel Dump Test Module for testing kernel crashes conditions:
   4  * induces system failures at predefined crashpoints and under predefined
   5  * operational conditions in order to evaluate the reliability of kernel
   6  * sanity checking and crash dumps obtained using different dumping
   7  * solutions.
   8  *
   9  * Copyright (C) IBM Corporation, 2006
  10  *
  11  * Author: Ankita Garg <ankita@in.ibm.com>
  12  *
  13  * It is adapted from the Linux Kernel Dump Test Tool by
  14  * 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 instructions
  19  */
  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
  30 #define DEFAULT_COUNT 10
  31
  32 static int lkdtm_debugfs_open(struct inode *inode, struct file *file);
  33 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
  34                 size_t count, loff_t *off);
  35 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
  36                             size_t count, loff_t *off);
  37
  38 #ifdef CONFIG_KPROBES
  39 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
  40 static ssize_t lkdtm_debugfs_entry(struct file *f,
  41                                    const char __user *user_buf,
  42                                    size_t count, loff_t *off);
  43 # define CRASHPOINT_KPROBE(_symbol)                             \
  44                 .kprobe = {                                     \
  45                         .symbol_name = (_symbol),               \
  46                         .pre_handler = lkdtm_kprobe_handler,    \
  47                 },
  48 # define CRASHPOINT_WRITE(_symbol)                              \
  49                 (_symbol) ? lkdtm_debugfs_entry : direct_entry
  50 #else
  51 # define CRASHPOINT_KPROBE(_symbol)
  52 # define CRASHPOINT_WRITE(_symbol)              direct_entry
  53 #endif
  54
  55 /* Crash points */
  56 struct crashpoint {
  57         const char *name;
  58         const struct file_operations fops;
  59         struct kprobe kprobe;
  60 };
  61
  62 #define CRASHPOINT(_name, _symbol)                              \
  63         {                                                       \
  64                 .name = _name,                                  \
  65                 .fops = {                                       \
  66                         .read   = lkdtm_debugfs_read,           \
  67                         .llseek = generic_file_llseek,          \
  68                         .open   = lkdtm_debugfs_open,           \
  69                         .write  = CRASHPOINT_WRITE(_symbol)     \
  70                 },                                              \
  71                 CRASHPOINT_KPROBE(_symbol)                      \
  72         }
  73
  74 /* Define the possible places where we can trigger a crash point. */
  75 static struct crashpoint crashpoints[] = {
  76         CRASHPOINT("DIRECT",             NULL),
  77 #ifdef CONFIG_KPROBES
  78         CRASHPOINT("INT_HARDWARE_ENTRY", "do_IRQ"),
  79         CRASHPOINT("INT_HW_IRQ_EN",      "handle_irq_event"),
  80         CRASHPOINT("INT_TASKLET_ENTRY",  "tasklet_action"),
  81         CRASHPOINT("FS_DEVRW",           "ll_rw_block"),
  82         CRASHPOINT("MEM_SWAPOUT",        "shrink_inactive_list"),
  83         CRASHPOINT("TIMERADD",           "hrtimer_start"),
  84         CRASHPOINT("SCSI_QUEUE_RQ",      "scsi_queue_rq"),
  85 #endif
  86 };
  87
  88
  89 /* Crash types. */
  90 struct crashtype {
  91         const char *name;
  92         void (*func)(void);
  93 };
  94
  95 #define CRASHTYPE(_name)                        \
  96         {                                       \
  97                 .name = __stringify(_name),     \
  98                 .func = lkdtm_ ## _name,        \
  99         }
 100
 101 /* Define the possible types of crashes that can be triggered. */
 102 static const struct crashtype crashtypes[] = {
 103         CRASHTYPE(PANIC),
 104         CRASHTYPE(BUG),
 105         CRASHTYPE(WARNING),
 106         CRASHTYPE(WARNING_MESSAGE),
 107         CRASHTYPE(EXCEPTION),
 108         CRASHTYPE(LOOP),
 109         CRASHTYPE(EXHAUST_STACK),
 110         CRASHTYPE(CORRUPT_STACK),
 111         CRASHTYPE(CORRUPT_STACK_STRONG),
 112         CRASHTYPE(REPORT_STACK),
 113         CRASHTYPE(CORRUPT_LIST_ADD),
 114         CRASHTYPE(CORRUPT_LIST_DEL),
 115         CRASHTYPE(STACK_GUARD_PAGE_LEADING),
 116         CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
 117         CRASHTYPE(UNSET_SMEP),
 118         CRASHTYPE(CORRUPT_PAC),
 119         CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
 120         CRASHTYPE(SLAB_LINEAR_OVERFLOW),
 121         CRASHTYPE(VMALLOC_LINEAR_OVERFLOW),
 122         CRASHTYPE(WRITE_AFTER_FREE),
 123         CRASHTYPE(READ_AFTER_FREE),
 124         CRASHTYPE(WRITE_BUDDY_AFTER_FREE),
 125         CRASHTYPE(READ_BUDDY_AFTER_FREE),
 126         CRASHTYPE(SLAB_INIT_ON_ALLOC),
 127         CRASHTYPE(BUDDY_INIT_ON_ALLOC),
 128         CRASHTYPE(SLAB_FREE_DOUBLE),
 129         CRASHTYPE(SLAB_FREE_CROSS),
 130         CRASHTYPE(SLAB_FREE_PAGE),
 131         CRASHTYPE(SOFTLOCKUP),
 132         CRASHTYPE(HARDLOCKUP),
 133         CRASHTYPE(SPINLOCKUP),
 134         CRASHTYPE(HUNG_TASK),
 135         CRASHTYPE(OVERFLOW_SIGNED),
 136         CRASHTYPE(OVERFLOW_UNSIGNED),
 137         CRASHTYPE(ARRAY_BOUNDS),
 138         CRASHTYPE(EXEC_DATA),
 139         CRASHTYPE(EXEC_STACK),
 140         CRASHTYPE(EXEC_KMALLOC),
 141         CRASHTYPE(EXEC_VMALLOC),
 142         CRASHTYPE(EXEC_RODATA),
 143         CRASHTYPE(EXEC_USERSPACE),
 144         CRASHTYPE(EXEC_NULL),
 145         CRASHTYPE(ACCESS_USERSPACE),
 146         CRASHTYPE(ACCESS_NULL),
 147         CRASHTYPE(WRITE_RO),
 148         CRASHTYPE(WRITE_RO_AFTER_INIT),
 149         CRASHTYPE(WRITE_KERN),
 150         CRASHTYPE(REFCOUNT_INC_OVERFLOW),
 151         CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
 152         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_OVERFLOW),
 153         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_OVERFLOW),
 154         CRASHTYPE(REFCOUNT_DEC_ZERO),
 155         CRASHTYPE(REFCOUNT_DEC_NEGATIVE),
 156         CRASHTYPE(REFCOUNT_DEC_AND_TEST_NEGATIVE),
 157         CRASHTYPE(REFCOUNT_SUB_AND_TEST_NEGATIVE),
 158         CRASHTYPE(REFCOUNT_INC_ZERO),
 159         CRASHTYPE(REFCOUNT_ADD_ZERO),
 160         CRASHTYPE(REFCOUNT_INC_SATURATED),
 161         CRASHTYPE(REFCOUNT_DEC_SATURATED),
 162         CRASHTYPE(REFCOUNT_ADD_SATURATED),
 163         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_SATURATED),
 164         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_SATURATED),
 165         CRASHTYPE(REFCOUNT_DEC_AND_TEST_SATURATED),
 166         CRASHTYPE(REFCOUNT_SUB_AND_TEST_SATURATED),
 167         CRASHTYPE(REFCOUNT_TIMING),
 168         CRASHTYPE(ATOMIC_TIMING),
 169         CRASHTYPE(USERCOPY_HEAP_SIZE_TO),
 170         CRASHTYPE(USERCOPY_HEAP_SIZE_FROM),
 171         CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO),
 172         CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM),
 173         CRASHTYPE(USERCOPY_STACK_FRAME_TO),
 174         CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
 175         CRASHTYPE(USERCOPY_STACK_BEYOND),
 176         CRASHTYPE(USERCOPY_KERNEL),
 177         CRASHTYPE(STACKLEAK_ERASING),
 178         CRASHTYPE(CFI_FORWARD_PROTO),
 179         CRASHTYPE(FORTIFIED_OBJECT),
 180         CRASHTYPE(FORTIFIED_SUBOBJECT),
 181         CRASHTYPE(FORTIFIED_STRSCPY),
 182         CRASHTYPE(DOUBLE_FAULT),
 183 #ifdef CONFIG_PPC_BOOK3S_64
 184         CRASHTYPE(PPC_SLB_MULTIHIT),
 185 #endif
 186 };
 187
 188
 189 /* Global kprobe entry and crashtype. */
 190 static struct kprobe *lkdtm_kprobe;
 191 static struct crashpoint *lkdtm_crashpoint;
 192 static const struct crashtype *lkdtm_crashtype;
 193
 194 /* Module parameters */
 195 static int recur_count = -1;
 196 module_param(recur_count, int, 0644);
 197 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 198
 199 static char* cpoint_name;
 200 module_param(cpoint_name, charp, 0444);
 201 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 202
 203 static char* cpoint_type;
 204 module_param(cpoint_type, charp, 0444);
 205 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 206                                 "hitting the crash point");
 207
 208 static int cpoint_count = DEFAULT_COUNT;
 209 module_param(cpoint_count, int, 0644);
 210 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 211                                 "crash point is to be hit to trigger action");
 212
 213
 214 /* Return the crashtype number or NULL if the name is invalid */
 215 static const struct crashtype *find_crashtype(const char *name)
 216 {
 217         int i;
 218
 219         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 220                 if (!strcmp(name, crashtypes[i].name))
 221                         return &crashtypes[i];
 222         }
 223
 224         return NULL;
 225 }
 226
 227 /*
 228  * This is forced noinline just so it distinctly shows up in the stackdump
 229  * which makes validation of expected lkdtm crashes easier.
 230  */
 231 static noinline void lkdtm_do_action(const struct crashtype *crashtype)
 232 {
 233         if (WARN_ON(!crashtype || !crashtype->func))
 234                 return;
 235         crashtype->func();
 236 }
 237
 238 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 239                                  const struct crashtype *crashtype)
 240 {
 241         int ret;
 242
 243         /* If this doesn't have a symbol, just call immediately. */
 244         if (!crashpoint->kprobe.symbol_name) {
 245                 lkdtm_do_action(crashtype);
 246                 return 0;
 247         }
 248
 249         if (lkdtm_kprobe != NULL)
 250                 unregister_kprobe(lkdtm_kprobe);
 251
 252         lkdtm_crashpoint = crashpoint;
 253         lkdtm_crashtype = crashtype;
 254         lkdtm_kprobe = &crashpoint->kprobe;
 255         ret = register_kprobe(lkdtm_kprobe);
 256         if (ret < 0) {
 257                 pr_info("Couldn't register kprobe %s\n",
 258                         crashpoint->kprobe.symbol_name);
 259                 lkdtm_kprobe = NULL;
 260                 lkdtm_crashpoint = NULL;
 261                 lkdtm_crashtype = NULL;
 262         }
 263
 264         return ret;
 265 }
 266
 267 #ifdef CONFIG_KPROBES
 268 /* Global crash counter and spinlock. */
 269 static int crash_count = DEFAULT_COUNT;
 270 static DEFINE_SPINLOCK(crash_count_lock);
 271
 272 /* Called by kprobe entry points. */
 273 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 274 {
 275         unsigned long flags;
 276         bool do_it = false;
 277
 278         if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
 279                 return 0;
 280
 281         spin_lock_irqsave(&crash_count_lock, flags);
 282         crash_count--;
 283         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 284                 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
 285
 286         if (crash_count == 0) {
 287                 do_it = true;
 288                 crash_count = cpoint_count;
 289         }
 290         spin_unlock_irqrestore(&crash_count_lock, flags);
 291
 292         if (do_it)
 293                 lkdtm_do_action(lkdtm_crashtype);
 294
 295         return 0;
 296 }
 297
 298 static ssize_t lkdtm_debugfs_entry(struct file *f,
 299                                    const char __user *user_buf,
 300                                    size_t count, loff_t *off)
 301 {
 302         struct crashpoint *crashpoint = file_inode(f)->i_private;
 303         const struct crashtype *crashtype = NULL;
 304         char *buf;
 305         int err;
 306
 307         if (count >= PAGE_SIZE)
 308                 return -EINVAL;
 309
 310         buf = (char *)__get_free_page(GFP_KERNEL);
 311         if (!buf)
 312                 return -ENOMEM;
 313         if (copy_from_user(buf, user_buf, count)) {
 314                 free_page((unsigned long) buf);
 315                 return -EFAULT;
 316         }
 317         /* NULL-terminate and remove enter */
 318         buf[count] = '\0';
 319         strim(buf);
 320
 321         crashtype = find_crashtype(buf);
 322         free_page((unsigned long)buf);
 323
 324         if (!crashtype)
 325                 return -EINVAL;
 326
 327         err = lkdtm_register_cpoint(crashpoint, crashtype);
 328         if (err < 0)
 329                 return err;
 330
 331         *off += count;
 332
 333         return count;
 334 }
 335 #endif
 336
 337 /* Generic read callback that just prints out the available crash types */
 338 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 339                 size_t count, loff_t *off)
 340 {
 341         char *buf;
 342         int i, n, out;
 343
 344         buf = (char *)__get_free_page(GFP_KERNEL);
 345         if (buf == NULL)
 346                 return -ENOMEM;
 347
 348         n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
 349         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 350                 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
 351                               crashtypes[i].name);
 352         }
 353         buf[n] = '\0';
 354
 355         out = simple_read_from_buffer(user_buf, count, off,
 356                                       buf, n);
 357         free_page((unsigned long) buf);
 358
 359         return out;
 360 }
 361
 362 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 363 {
 364         return 0;
 365 }
 366
 367 /* Special entry to just crash directly. Available without KPROBEs */
 368 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 369                 size_t count, loff_t *off)
 370 {
 371         const struct crashtype *crashtype;
 372         char *buf;
 373
 374         if (count >= PAGE_SIZE)
 375                 return -EINVAL;
 376         if (count < 1)
 377                 return -EINVAL;
 378
 379         buf = (char *)__get_free_page(GFP_KERNEL);
 380         if (!buf)
 381                 return -ENOMEM;
 382         if (copy_from_user(buf, user_buf, count)) {
 383                 free_page((unsigned long) buf);
 384                 return -EFAULT;
 385         }
 386         /* NULL-terminate and remove enter */
 387         buf[count] = '\0';
 388         strim(buf);
 389
 390         crashtype = find_crashtype(buf);
 391         free_page((unsigned long) buf);
 392         if (!crashtype)
 393                 return -EINVAL;
 394
 395         pr_info("Performing direct entry %s\n", crashtype->name);
 396         lkdtm_do_action(crashtype);
 397         *off += count;
 398
 399         return count;
 400 }
 401
 402 #ifndef MODULE
 403 /*
 404  * To avoid needing to export parse_args(), just don't use this code
 405  * when LKDTM is built as a module.
 406  */
 407 struct check_cmdline_args {
 408         const char *param;
 409         int value;
 410 };
 411
 412 static int lkdtm_parse_one(char *param, char *val,
 413                            const char *unused, void *arg)
 414 {
 415         struct check_cmdline_args *args = arg;
 416
 417         /* short circuit if we already found a value. */
 418         if (args->value != -ESRCH)
 419                 return 0;
 420         if (strncmp(param, args->param, strlen(args->param)) == 0) {
 421                 bool bool_result;
 422                 int ret;
 423
 424                 ret = kstrtobool(val, &bool_result);
 425                 if (ret == 0)
 426                         args->value = bool_result;
 427         }
 428         return 0;
 429 }
 430
 431 int lkdtm_check_bool_cmdline(const char *param)
 432 {
 433         char *command_line;
 434         struct check_cmdline_args args = {
 435                 .param = param,
 436                 .value = -ESRCH,
 437         };
 438
 439         command_line = kstrdup(saved_command_line, GFP_KERNEL);
 440         if (!command_line)
 441                 return -ENOMEM;
 442
 443         parse_args("Setting sysctl args", command_line,
 444                    NULL, 0, -1, -1, &args, lkdtm_parse_one);
 445
 446         kfree(command_line);
 447
 448         return args.value;
 449 }
 450 #endif
 451
 452 static struct dentry *lkdtm_debugfs_root;
 453
 454 static int __init lkdtm_module_init(void)
 455 {
 456         struct crashpoint *crashpoint = NULL;
 457         const struct crashtype *crashtype = NULL;
 458         int ret;
 459         int i;
 460
 461         /* Neither or both of these need to be set */
 462         if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
 463                 pr_err("Need both cpoint_type and cpoint_name or neither\n");
 464                 return -EINVAL;
 465         }
 466
 467         if (cpoint_type) {
 468                 crashtype = find_crashtype(cpoint_type);
 469                 if (!crashtype) {
 470                         pr_err("Unknown crashtype '%s'\n", cpoint_type);
 471                         return -EINVAL;
 472                 }
 473         }
 474
 475         if (cpoint_name) {
 476                 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 477                         if (!strcmp(cpoint_name, crashpoints[i].name))
 478                                 crashpoint = &crashpoints[i];
 479                 }
 480
 481                 /* Refuse unknown crashpoints. */
 482                 if (!crashpoint) {
 483                         pr_err("Invalid crashpoint %s\n", cpoint_name);
 484                         return -EINVAL;
 485                 }
 486         }
 487
 488 #ifdef CONFIG_KPROBES
 489         /* Set crash count. */
 490         crash_count = cpoint_count;
 491 #endif
 492
 493         /* Handle test-specific initialization. */
 494         lkdtm_bugs_init(&recur_count);
 495         lkdtm_perms_init();
 496         lkdtm_usercopy_init();
 497         lkdtm_heap_init();
 498
 499         /* Register debugfs interface */
 500         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 501
 502         /* Install debugfs trigger files. */
 503         for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 504                 struct crashpoint *cur = &crashpoints[i];
 505
 506                 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
 507                                     &cur->fops);
 508         }
 509
 510         /* Install crashpoint if one was selected. */
 511         if (crashpoint) {
 512                 ret = lkdtm_register_cpoint(crashpoint, crashtype);
 513                 if (ret < 0) {
 514                         pr_info("Invalid crashpoint %s\n", crashpoint->name);
 515                         goto out_err;
 516                 }
 517                 pr_info("Crash point %s of type %s registered\n",
 518                         crashpoint->name, cpoint_type);
 519         } else {
 520                 pr_info("No crash points registered, enable through debugfs\n");
 521         }
 522
 523         return 0;
 524
 525 out_err:
 526         debugfs_remove_recursive(lkdtm_debugfs_root);
 527         return ret;
 528 }
 529
 530 static void __exit lkdtm_module_exit(void)
 531 {
 532         debugfs_remove_recursive(lkdtm_debugfs_root);
 533
 534         /* Handle test-specific clean-up. */
 535         lkdtm_heap_exit();
 536         lkdtm_usercopy_exit();
 537
 538         if (lkdtm_kprobe != NULL)
 539                 unregister_kprobe(lkdtm_kprobe);
 540
 541         pr_info("Crash point unregistered\n");
 542 }
 543
 544 module_init(lkdtm_module_init);
 545 module_exit(lkdtm_module_exit);
 546
 547 MODULE_LICENSE("GPL");
 548 MODULE_DESCRIPTION("Kernel crash testing module");