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/utsname.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_QUEUE_RQ",      "scsi_queue_rq"),
  86 #endif
  87 };
  88
  89
  90 /* Crash types. */
  91 struct crashtype {
  92         const char *name;
  93         void (*func)(void);
  94 };
  95
  96 #define CRASHTYPE(_name)                        \
  97         {                                       \
  98                 .name = __stringify(_name),     \
  99                 .func = lkdtm_ ## _name,        \
 100         }
 101
 102 /* Define the possible types of crashes that can be triggered. */
 103 static const struct crashtype crashtypes[] = {
 104         CRASHTYPE(PANIC),
 105         CRASHTYPE(BUG),
 106         CRASHTYPE(WARNING),
 107         CRASHTYPE(WARNING_MESSAGE),
 108         CRASHTYPE(EXCEPTION),
 109         CRASHTYPE(LOOP),
 110         CRASHTYPE(EXHAUST_STACK),
 111         CRASHTYPE(CORRUPT_STACK),
 112         CRASHTYPE(CORRUPT_STACK_STRONG),
 113         CRASHTYPE(REPORT_STACK),
 114         CRASHTYPE(CORRUPT_LIST_ADD),
 115         CRASHTYPE(CORRUPT_LIST_DEL),
 116         CRASHTYPE(STACK_GUARD_PAGE_LEADING),
 117         CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
 118         CRASHTYPE(UNSET_SMEP),
 119         CRASHTYPE(CORRUPT_PAC),
 120         CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
 121         CRASHTYPE(SLAB_LINEAR_OVERFLOW),
 122         CRASHTYPE(VMALLOC_LINEAR_OVERFLOW),
 123         CRASHTYPE(WRITE_AFTER_FREE),
 124         CRASHTYPE(READ_AFTER_FREE),
 125         CRASHTYPE(WRITE_BUDDY_AFTER_FREE),
 126         CRASHTYPE(READ_BUDDY_AFTER_FREE),
 127         CRASHTYPE(SLAB_INIT_ON_ALLOC),
 128         CRASHTYPE(BUDDY_INIT_ON_ALLOC),
 129         CRASHTYPE(SLAB_FREE_DOUBLE),
 130         CRASHTYPE(SLAB_FREE_CROSS),
 131         CRASHTYPE(SLAB_FREE_PAGE),
 132         CRASHTYPE(SOFTLOCKUP),
 133         CRASHTYPE(HARDLOCKUP),
 134         CRASHTYPE(SPINLOCKUP),
 135         CRASHTYPE(HUNG_TASK),
 136         CRASHTYPE(OVERFLOW_SIGNED),
 137         CRASHTYPE(OVERFLOW_UNSIGNED),
 138         CRASHTYPE(ARRAY_BOUNDS),
 139         CRASHTYPE(EXEC_DATA),
 140         CRASHTYPE(EXEC_STACK),
 141         CRASHTYPE(EXEC_KMALLOC),
 142         CRASHTYPE(EXEC_VMALLOC),
 143         CRASHTYPE(EXEC_RODATA),
 144         CRASHTYPE(EXEC_USERSPACE),
 145         CRASHTYPE(EXEC_NULL),
 146         CRASHTYPE(ACCESS_USERSPACE),
 147         CRASHTYPE(ACCESS_NULL),
 148         CRASHTYPE(WRITE_RO),
 149         CRASHTYPE(WRITE_RO_AFTER_INIT),
 150         CRASHTYPE(WRITE_KERN),
 151         CRASHTYPE(REFCOUNT_INC_OVERFLOW),
 152         CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
 153         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_OVERFLOW),
 154         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_OVERFLOW),
 155         CRASHTYPE(REFCOUNT_DEC_ZERO),
 156         CRASHTYPE(REFCOUNT_DEC_NEGATIVE),
 157         CRASHTYPE(REFCOUNT_DEC_AND_TEST_NEGATIVE),
 158         CRASHTYPE(REFCOUNT_SUB_AND_TEST_NEGATIVE),
 159         CRASHTYPE(REFCOUNT_INC_ZERO),
 160         CRASHTYPE(REFCOUNT_ADD_ZERO),
 161         CRASHTYPE(REFCOUNT_INC_SATURATED),
 162         CRASHTYPE(REFCOUNT_DEC_SATURATED),
 163         CRASHTYPE(REFCOUNT_ADD_SATURATED),
 164         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_SATURATED),
 165         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_SATURATED),
 166         CRASHTYPE(REFCOUNT_DEC_AND_TEST_SATURATED),
 167         CRASHTYPE(REFCOUNT_SUB_AND_TEST_SATURATED),
 168         CRASHTYPE(REFCOUNT_TIMING),
 169         CRASHTYPE(ATOMIC_TIMING),
 170         CRASHTYPE(USERCOPY_HEAP_SIZE_TO),
 171         CRASHTYPE(USERCOPY_HEAP_SIZE_FROM),
 172         CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO),
 173         CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM),
 174         CRASHTYPE(USERCOPY_STACK_FRAME_TO),
 175         CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
 176         CRASHTYPE(USERCOPY_STACK_BEYOND),
 177         CRASHTYPE(USERCOPY_KERNEL),
 178         CRASHTYPE(STACKLEAK_ERASING),
 179         CRASHTYPE(CFI_FORWARD_PROTO),
 180         CRASHTYPE(FORTIFIED_OBJECT),
 181         CRASHTYPE(FORTIFIED_SUBOBJECT),
 182         CRASHTYPE(FORTIFIED_STRSCPY),
 183         CRASHTYPE(DOUBLE_FAULT),
 184 #ifdef CONFIG_PPC_BOOK3S_64
 185         CRASHTYPE(PPC_SLB_MULTIHIT),
 186 #endif
 187 };
 188
 189
 190 /* Global kprobe entry and crashtype. */
 191 static struct kprobe *lkdtm_kprobe;
 192 static struct crashpoint *lkdtm_crashpoint;
 193 static const struct crashtype *lkdtm_crashtype;
 194
 195 /* Module parameters */
 196 static int recur_count = -1;
 197 module_param(recur_count, int, 0644);
 198 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 199
 200 static char* cpoint_name;
 201 module_param(cpoint_name, charp, 0444);
 202 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 203
 204 static char* cpoint_type;
 205 module_param(cpoint_type, charp, 0444);
 206 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 207                                 "hitting the crash point");
 208
 209 static int cpoint_count = DEFAULT_COUNT;
 210 module_param(cpoint_count, int, 0644);
 211 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 212                                 "crash point is to be hit to trigger action");
 213
 214 /* For test debug reporting. */
 215 char *lkdtm_kernel_info;
 216
 217 /* Return the crashtype number or NULL if the name is invalid */
 218 static const struct crashtype *find_crashtype(const char *name)
 219 {
 220         int i;
 221
 222         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 223                 if (!strcmp(name, crashtypes[i].name))
 224                         return &crashtypes[i];
 225         }
 226
 227         return NULL;
 228 }
 229
 230 /*
 231  * This is forced noinline just so it distinctly shows up in the stackdump
 232  * which makes validation of expected lkdtm crashes easier.
 233  */
 234 static noinline void lkdtm_do_action(const struct crashtype *crashtype)
 235 {
 236         if (WARN_ON(!crashtype || !crashtype->func))
 237                 return;
 238         crashtype->func();
 239 }
 240
 241 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 242                                  const struct crashtype *crashtype)
 243 {
 244         int ret;
 245
 246         /* If this doesn't have a symbol, just call immediately. */
 247         if (!crashpoint->kprobe.symbol_name) {
 248                 lkdtm_do_action(crashtype);
 249                 return 0;
 250         }
 251
 252         if (lkdtm_kprobe != NULL)
 253                 unregister_kprobe(lkdtm_kprobe);
 254
 255         lkdtm_crashpoint = crashpoint;
 256         lkdtm_crashtype = crashtype;
 257         lkdtm_kprobe = &crashpoint->kprobe;
 258         ret = register_kprobe(lkdtm_kprobe);
 259         if (ret < 0) {
 260                 pr_info("Couldn't register kprobe %s\n",
 261                         crashpoint->kprobe.symbol_name);
 262                 lkdtm_kprobe = NULL;
 263                 lkdtm_crashpoint = NULL;
 264                 lkdtm_crashtype = NULL;
 265         }
 266
 267         return ret;
 268 }
 269
 270 #ifdef CONFIG_KPROBES
 271 /* Global crash counter and spinlock. */
 272 static int crash_count = DEFAULT_COUNT;
 273 static DEFINE_SPINLOCK(crash_count_lock);
 274
 275 /* Called by kprobe entry points. */
 276 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 277 {
 278         unsigned long flags;
 279         bool do_it = false;
 280
 281         if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
 282                 return 0;
 283
 284         spin_lock_irqsave(&crash_count_lock, flags);
 285         crash_count--;
 286         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 287                 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
 288
 289         if (crash_count == 0) {
 290                 do_it = true;
 291                 crash_count = cpoint_count;
 292         }
 293         spin_unlock_irqrestore(&crash_count_lock, flags);
 294
 295         if (do_it)
 296                 lkdtm_do_action(lkdtm_crashtype);
 297
 298         return 0;
 299 }
 300
 301 static ssize_t lkdtm_debugfs_entry(struct file *f,
 302                                    const char __user *user_buf,
 303                                    size_t count, loff_t *off)
 304 {
 305         struct crashpoint *crashpoint = file_inode(f)->i_private;
 306         const struct crashtype *crashtype = NULL;
 307         char *buf;
 308         int err;
 309
 310         if (count >= PAGE_SIZE)
 311                 return -EINVAL;
 312
 313         buf = (char *)__get_free_page(GFP_KERNEL);
 314         if (!buf)
 315                 return -ENOMEM;
 316         if (copy_from_user(buf, user_buf, count)) {
 317                 free_page((unsigned long) buf);
 318                 return -EFAULT;
 319         }
 320         /* NULL-terminate and remove enter */
 321         buf[count] = '\0';
 322         strim(buf);
 323
 324         crashtype = find_crashtype(buf);
 325         free_page((unsigned long)buf);
 326
 327         if (!crashtype)
 328                 return -EINVAL;
 329
 330         err = lkdtm_register_cpoint(crashpoint, crashtype);
 331         if (err < 0)
 332                 return err;
 333
 334         *off += count;
 335
 336         return count;
 337 }
 338 #endif
 339
 340 /* Generic read callback that just prints out the available crash types */
 341 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 342                 size_t count, loff_t *off)
 343 {
 344         char *buf;
 345         int i, n, out;
 346
 347         buf = (char *)__get_free_page(GFP_KERNEL);
 348         if (buf == NULL)
 349                 return -ENOMEM;
 350
 351         n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
 352         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 353                 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
 354                               crashtypes[i].name);
 355         }
 356         buf[n] = '\0';
 357
 358         out = simple_read_from_buffer(user_buf, count, off,
 359                                       buf, n);
 360         free_page((unsigned long) buf);
 361
 362         return out;
 363 }
 364
 365 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 366 {
 367         return 0;
 368 }
 369
 370 /* Special entry to just crash directly. Available without KPROBEs */
 371 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 372                 size_t count, loff_t *off)
 373 {
 374         const struct crashtype *crashtype;
 375         char *buf;
 376
 377         if (count >= PAGE_SIZE)
 378                 return -EINVAL;
 379         if (count < 1)
 380                 return -EINVAL;
 381
 382         buf = (char *)__get_free_page(GFP_KERNEL);
 383         if (!buf)
 384                 return -ENOMEM;
 385         if (copy_from_user(buf, user_buf, count)) {
 386                 free_page((unsigned long) buf);
 387                 return -EFAULT;
 388         }
 389         /* NULL-terminate and remove enter */
 390         buf[count] = '\0';
 391         strim(buf);
 392
 393         crashtype = find_crashtype(buf);
 394         free_page((unsigned long) buf);
 395         if (!crashtype)
 396                 return -EINVAL;
 397
 398         pr_info("Performing direct entry %s\n", crashtype->name);
 399         lkdtm_do_action(crashtype);
 400         *off += count;
 401
 402         return count;
 403 }
 404
 405 #ifndef MODULE
 406 /*
 407  * To avoid needing to export parse_args(), just don't use this code
 408  * when LKDTM is built as a module.
 409  */
 410 struct check_cmdline_args {
 411         const char *param;
 412         int value;
 413 };
 414
 415 static int lkdtm_parse_one(char *param, char *val,
 416                            const char *unused, void *arg)
 417 {
 418         struct check_cmdline_args *args = arg;
 419
 420         /* short circuit if we already found a value. */
 421         if (args->value != -ESRCH)
 422                 return 0;
 423         if (strncmp(param, args->param, strlen(args->param)) == 0) {
 424                 bool bool_result;
 425                 int ret;
 426
 427                 ret = kstrtobool(val, &bool_result);
 428                 if (ret == 0)
 429                         args->value = bool_result;
 430         }
 431         return 0;
 432 }
 433
 434 int lkdtm_check_bool_cmdline(const char *param)
 435 {
 436         char *command_line;
 437         struct check_cmdline_args args = {
 438                 .param = param,
 439                 .value = -ESRCH,
 440         };
 441
 442         command_line = kstrdup(saved_command_line, GFP_KERNEL);
 443         if (!command_line)
 444                 return -ENOMEM;
 445
 446         parse_args("Setting sysctl args", command_line,
 447                    NULL, 0, -1, -1, &args, lkdtm_parse_one);
 448
 449         kfree(command_line);
 450
 451         return args.value;
 452 }
 453 #endif
 454
 455 static struct dentry *lkdtm_debugfs_root;
 456
 457 static int __init lkdtm_module_init(void)
 458 {
 459         struct crashpoint *crashpoint = NULL;
 460         const struct crashtype *crashtype = NULL;
 461         int ret;
 462         int i;
 463
 464         /* Neither or both of these need to be set */
 465         if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
 466                 pr_err("Need both cpoint_type and cpoint_name or neither\n");
 467                 return -EINVAL;
 468         }
 469
 470         if (cpoint_type) {
 471                 crashtype = find_crashtype(cpoint_type);
 472                 if (!crashtype) {
 473                         pr_err("Unknown crashtype '%s'\n", cpoint_type);
 474                         return -EINVAL;
 475                 }
 476         }
 477
 478         if (cpoint_name) {
 479                 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 480                         if (!strcmp(cpoint_name, crashpoints[i].name))
 481                                 crashpoint = &crashpoints[i];
 482                 }
 483
 484                 /* Refuse unknown crashpoints. */
 485                 if (!crashpoint) {
 486                         pr_err("Invalid crashpoint %s\n", cpoint_name);
 487                         return -EINVAL;
 488                 }
 489         }
 490
 491 #ifdef CONFIG_KPROBES
 492         /* Set crash count. */
 493         crash_count = cpoint_count;
 494 #endif
 495
 496         /* Common initialization. */
 497         lkdtm_kernel_info = kasprintf(GFP_KERNEL, "kernel (%s %s)",
 498                                       init_uts_ns.name.release,
 499                                       init_uts_ns.name.machine);
 500
 501         /* Handle test-specific initialization. */
 502         lkdtm_bugs_init(&recur_count);
 503         lkdtm_perms_init();
 504         lkdtm_usercopy_init();
 505         lkdtm_heap_init();
 506
 507         /* Register debugfs interface */
 508         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 509
 510         /* Install debugfs trigger files. */
 511         for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 512                 struct crashpoint *cur = &crashpoints[i];
 513
 514                 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
 515                                     &cur->fops);
 516         }
 517
 518         /* Install crashpoint if one was selected. */
 519         if (crashpoint) {
 520                 ret = lkdtm_register_cpoint(crashpoint, crashtype);
 521                 if (ret < 0) {
 522                         pr_info("Invalid crashpoint %s\n", crashpoint->name);
 523                         goto out_err;
 524                 }
 525                 pr_info("Crash point %s of type %s registered\n",
 526                         crashpoint->name, cpoint_type);
 527         } else {
 528                 pr_info("No crash points registered, enable through debugfs\n");
 529         }
 530
 531         return 0;
 532
 533 out_err:
 534         debugfs_remove_recursive(lkdtm_debugfs_root);
 535         return ret;
 536 }
 537
 538 static void __exit lkdtm_module_exit(void)
 539 {
 540         debugfs_remove_recursive(lkdtm_debugfs_root);
 541
 542         /* Handle test-specific clean-up. */
 543         lkdtm_heap_exit();
 544         lkdtm_usercopy_exit();
 545
 546         if (lkdtm_kprobe != NULL)
 547                 unregister_kprobe(lkdtm_kprobe);
 548
 549         kfree(lkdtm_kernel_info);
 550
 551         pr_info("Crash point unregistered\n");
 552 }
 553
 554 module_init(lkdtm_module_init);
 555 module_exit(lkdtm_module_exit);
 556
 557 MODULE_LICENSE("GPL");
 558 MODULE_DESCRIPTION("Kernel crash testing module");