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_DISPATCH_CMD",  "scsi_dispatch_cmd"),
  85         CRASHPOINT("IDE_CORE_CP",        "generic_ide_ioctl"),
  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(FORTIFY_OBJECT),
 122         CRASHTYPE(FORTIFY_SUBOBJECT),
 123         CRASHTYPE(SLAB_LINEAR_OVERFLOW),
 124         CRASHTYPE(VMALLOC_LINEAR_OVERFLOW),
 125         CRASHTYPE(WRITE_AFTER_FREE),
 126         CRASHTYPE(READ_AFTER_FREE),
 127         CRASHTYPE(WRITE_BUDDY_AFTER_FREE),
 128         CRASHTYPE(READ_BUDDY_AFTER_FREE),
 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_STRSCPY),
 181 #ifdef CONFIG_X86_32
 182         CRASHTYPE(DOUBLE_FAULT),
 183 #endif
 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
 215 /* Return the crashtype number or NULL if the name is invalid */
 216 static const struct crashtype *find_crashtype(const char *name)
 217 {
 218         int i;
 219
 220         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 221                 if (!strcmp(name, crashtypes[i].name))
 222                         return &crashtypes[i];
 223         }
 224
 225         return NULL;
 226 }
 227
 228 /*
 229  * This is forced noinline just so it distinctly shows up in the stackdump
 230  * which makes validation of expected lkdtm crashes easier.
 231  */
 232 static noinline void lkdtm_do_action(const struct crashtype *crashtype)
 233 {
 234         if (WARN_ON(!crashtype || !crashtype->func))
 235                 return;
 236         crashtype->func();
 237 }
 238
 239 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 240                                  const struct crashtype *crashtype)
 241 {
 242         int ret;
 243
 244         /* If this doesn't have a symbol, just call immediately. */
 245         if (!crashpoint->kprobe.symbol_name) {
 246                 lkdtm_do_action(crashtype);
 247                 return 0;
 248         }
 249
 250         if (lkdtm_kprobe != NULL)
 251                 unregister_kprobe(lkdtm_kprobe);
 252
 253         lkdtm_crashpoint = crashpoint;
 254         lkdtm_crashtype = crashtype;
 255         lkdtm_kprobe = &crashpoint->kprobe;
 256         ret = register_kprobe(lkdtm_kprobe);
 257         if (ret < 0) {
 258                 pr_info("Couldn't register kprobe %s\n",
 259                         crashpoint->kprobe.symbol_name);
 260                 lkdtm_kprobe = NULL;
 261                 lkdtm_crashpoint = NULL;
 262                 lkdtm_crashtype = NULL;
 263         }
 264
 265         return ret;
 266 }
 267
 268 #ifdef CONFIG_KPROBES
 269 /* Global crash counter and spinlock. */
 270 static int crash_count = DEFAULT_COUNT;
 271 static DEFINE_SPINLOCK(crash_count_lock);
 272
 273 /* Called by kprobe entry points. */
 274 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 275 {
 276         unsigned long flags;
 277         bool do_it = false;
 278
 279         if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
 280                 return 0;
 281
 282         spin_lock_irqsave(&crash_count_lock, flags);
 283         crash_count--;
 284         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 285                 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
 286
 287         if (crash_count == 0) {
 288                 do_it = true;
 289                 crash_count = cpoint_count;
 290         }
 291         spin_unlock_irqrestore(&crash_count_lock, flags);
 292
 293         if (do_it)
 294                 lkdtm_do_action(lkdtm_crashtype);
 295
 296         return 0;
 297 }
 298
 299 static ssize_t lkdtm_debugfs_entry(struct file *f,
 300                                    const char __user *user_buf,
 301                                    size_t count, loff_t *off)
 302 {
 303         struct crashpoint *crashpoint = file_inode(f)->i_private;
 304         const struct crashtype *crashtype = NULL;
 305         char *buf;
 306         int err;
 307
 308         if (count >= PAGE_SIZE)
 309                 return -EINVAL;
 310
 311         buf = (char *)__get_free_page(GFP_KERNEL);
 312         if (!buf)
 313                 return -ENOMEM;
 314         if (copy_from_user(buf, user_buf, count)) {
 315                 free_page((unsigned long) buf);
 316                 return -EFAULT;
 317         }
 318         /* NULL-terminate and remove enter */
 319         buf[count] = '\0';
 320         strim(buf);
 321
 322         crashtype = find_crashtype(buf);
 323         free_page((unsigned long)buf);
 324
 325         if (!crashtype)
 326                 return -EINVAL;
 327
 328         err = lkdtm_register_cpoint(crashpoint, crashtype);
 329         if (err < 0)
 330                 return err;
 331
 332         *off += count;
 333
 334         return count;
 335 }
 336 #endif
 337
 338 /* Generic read callback that just prints out the available crash types */
 339 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 340                 size_t count, loff_t *off)
 341 {
 342         char *buf;
 343         int i, n, out;
 344
 345         buf = (char *)__get_free_page(GFP_KERNEL);
 346         if (buf == NULL)
 347                 return -ENOMEM;
 348
 349         n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
 350         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 351                 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
 352                               crashtypes[i].name);
 353         }
 354         buf[n] = '\0';
 355
 356         out = simple_read_from_buffer(user_buf, count, off,
 357                                       buf, n);
 358         free_page((unsigned long) buf);
 359
 360         return out;
 361 }
 362
 363 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 364 {
 365         return 0;
 366 }
 367
 368 /* Special entry to just crash directly. Available without KPROBEs */
 369 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 370                 size_t count, loff_t *off)
 371 {
 372         const struct crashtype *crashtype;
 373         char *buf;
 374
 375         if (count >= PAGE_SIZE)
 376                 return -EINVAL;
 377         if (count < 1)
 378                 return -EINVAL;
 379
 380         buf = (char *)__get_free_page(GFP_KERNEL);
 381         if (!buf)
 382                 return -ENOMEM;
 383         if (copy_from_user(buf, user_buf, count)) {
 384                 free_page((unsigned long) buf);
 385                 return -EFAULT;
 386         }
 387         /* NULL-terminate and remove enter */
 388         buf[count] = '\0';
 389         strim(buf);
 390
 391         crashtype = find_crashtype(buf);
 392         free_page((unsigned long) buf);
 393         if (!crashtype)
 394                 return -EINVAL;
 395
 396         pr_info("Performing direct entry %s\n", crashtype->name);
 397         lkdtm_do_action(crashtype);
 398         *off += count;
 399
 400         return count;
 401 }
 402
 403 static struct dentry *lkdtm_debugfs_root;
 404
 405 static int __init lkdtm_module_init(void)
 406 {
 407         struct crashpoint *crashpoint = NULL;
 408         const struct crashtype *crashtype = NULL;
 409         int ret;
 410         int i;
 411
 412         /* Neither or both of these need to be set */
 413         if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
 414                 pr_err("Need both cpoint_type and cpoint_name or neither\n");
 415                 return -EINVAL;
 416         }
 417
 418         if (cpoint_type) {
 419                 crashtype = find_crashtype(cpoint_type);
 420                 if (!crashtype) {
 421                         pr_err("Unknown crashtype '%s'\n", cpoint_type);
 422                         return -EINVAL;
 423                 }
 424         }
 425
 426         if (cpoint_name) {
 427                 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 428                         if (!strcmp(cpoint_name, crashpoints[i].name))
 429                                 crashpoint = &crashpoints[i];
 430                 }
 431
 432                 /* Refuse unknown crashpoints. */
 433                 if (!crashpoint) {
 434                         pr_err("Invalid crashpoint %s\n", cpoint_name);
 435                         return -EINVAL;
 436                 }
 437         }
 438
 439 #ifdef CONFIG_KPROBES
 440         /* Set crash count. */
 441         crash_count = cpoint_count;
 442 #endif
 443
 444         /* Handle test-specific initialization. */
 445         lkdtm_bugs_init(&recur_count);
 446         lkdtm_perms_init();
 447         lkdtm_usercopy_init();
 448         lkdtm_heap_init();
 449
 450         /* Register debugfs interface */
 451         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 452
 453         /* Install debugfs trigger files. */
 454         for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 455                 struct crashpoint *cur = &crashpoints[i];
 456
 457                 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
 458                                     &cur->fops);
 459         }
 460
 461         /* Install crashpoint if one was selected. */
 462         if (crashpoint) {
 463                 ret = lkdtm_register_cpoint(crashpoint, crashtype);
 464                 if (ret < 0) {
 465                         pr_info("Invalid crashpoint %s\n", crashpoint->name);
 466                         goto out_err;
 467                 }
 468                 pr_info("Crash point %s of type %s registered\n",
 469                         crashpoint->name, cpoint_type);
 470         } else {
 471                 pr_info("No crash points registered, enable through debugfs\n");
 472         }
 473
 474         return 0;
 475
 476 out_err:
 477         debugfs_remove_recursive(lkdtm_debugfs_root);
 478         return ret;
 479 }
 480
 481 static void __exit lkdtm_module_exit(void)
 482 {
 483         debugfs_remove_recursive(lkdtm_debugfs_root);
 484
 485         /* Handle test-specific clean-up. */
 486         lkdtm_heap_exit();
 487         lkdtm_usercopy_exit();
 488
 489         if (lkdtm_kprobe != NULL)
 490                 unregister_kprobe(lkdtm_kprobe);
 491
 492         pr_info("Crash point unregistered\n");
 493 }
 494
 495 module_init(lkdtm_module_init);
 496 module_exit(lkdtm_module_exit);
 497
 498 MODULE_LICENSE("GPL");
 499 MODULE_DESCRIPTION("Kernel crash testing module");