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