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(EXCEPTION),
 108         CRASHTYPE(LOOP),
 109         CRASHTYPE(EXHAUST_STACK),
 110         CRASHTYPE(CORRUPT_STACK),
 111         CRASHTYPE(CORRUPT_STACK_STRONG),
 112         CRASHTYPE(CORRUPT_LIST_ADD),
 113         CRASHTYPE(CORRUPT_LIST_DEL),
 114         CRASHTYPE(CORRUPT_USER_DS),
 115         CRASHTYPE(STACK_GUARD_PAGE_LEADING),
 116         CRASHTYPE(STACK_GUARD_PAGE_TRAILING),
 117         CRASHTYPE(UNSET_SMEP),
 118         CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),
 119         CRASHTYPE(OVERWRITE_ALLOCATION),
 120         CRASHTYPE(WRITE_AFTER_FREE),
 121         CRASHTYPE(READ_AFTER_FREE),
 122         CRASHTYPE(WRITE_BUDDY_AFTER_FREE),
 123         CRASHTYPE(READ_BUDDY_AFTER_FREE),
 124         CRASHTYPE(SLAB_FREE_DOUBLE),
 125         CRASHTYPE(SLAB_FREE_CROSS),
 126         CRASHTYPE(SLAB_FREE_PAGE),
 127         CRASHTYPE(SOFTLOCKUP),
 128         CRASHTYPE(HARDLOCKUP),
 129         CRASHTYPE(SPINLOCKUP),
 130         CRASHTYPE(HUNG_TASK),
 131         CRASHTYPE(EXEC_DATA),
 132         CRASHTYPE(EXEC_STACK),
 133         CRASHTYPE(EXEC_KMALLOC),
 134         CRASHTYPE(EXEC_VMALLOC),
 135         CRASHTYPE(EXEC_RODATA),
 136         CRASHTYPE(EXEC_USERSPACE),
 137         CRASHTYPE(EXEC_NULL),
 138         CRASHTYPE(ACCESS_USERSPACE),
 139         CRASHTYPE(ACCESS_NULL),
 140         CRASHTYPE(WRITE_RO),
 141         CRASHTYPE(WRITE_RO_AFTER_INIT),
 142         CRASHTYPE(WRITE_KERN),
 143         CRASHTYPE(REFCOUNT_INC_OVERFLOW),
 144         CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
 145         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_OVERFLOW),
 146         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_OVERFLOW),
 147         CRASHTYPE(REFCOUNT_DEC_ZERO),
 148         CRASHTYPE(REFCOUNT_DEC_NEGATIVE),
 149         CRASHTYPE(REFCOUNT_DEC_AND_TEST_NEGATIVE),
 150         CRASHTYPE(REFCOUNT_SUB_AND_TEST_NEGATIVE),
 151         CRASHTYPE(REFCOUNT_INC_ZERO),
 152         CRASHTYPE(REFCOUNT_ADD_ZERO),
 153         CRASHTYPE(REFCOUNT_INC_SATURATED),
 154         CRASHTYPE(REFCOUNT_DEC_SATURATED),
 155         CRASHTYPE(REFCOUNT_ADD_SATURATED),
 156         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_SATURATED),
 157         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_SATURATED),
 158         CRASHTYPE(REFCOUNT_DEC_AND_TEST_SATURATED),
 159         CRASHTYPE(REFCOUNT_SUB_AND_TEST_SATURATED),
 160         CRASHTYPE(REFCOUNT_TIMING),
 161         CRASHTYPE(ATOMIC_TIMING),
 162         CRASHTYPE(USERCOPY_HEAP_SIZE_TO),
 163         CRASHTYPE(USERCOPY_HEAP_SIZE_FROM),
 164         CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO),
 165         CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM),
 166         CRASHTYPE(USERCOPY_STACK_FRAME_TO),
 167         CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
 168         CRASHTYPE(USERCOPY_STACK_BEYOND),
 169         CRASHTYPE(USERCOPY_KERNEL),
 170         CRASHTYPE(USERCOPY_KERNEL_DS),
 171         CRASHTYPE(STACKLEAK_ERASING),
 172 };
 173
 174
 175 /* Global kprobe entry and crashtype. */
 176 static struct kprobe *lkdtm_kprobe;
 177 static struct crashpoint *lkdtm_crashpoint;
 178 static const struct crashtype *lkdtm_crashtype;
 179
 180 /* Module parameters */
 181 static int recur_count = -1;
 182 module_param(recur_count, int, 0644);
 183 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 184
 185 static char* cpoint_name;
 186 module_param(cpoint_name, charp, 0444);
 187 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 188
 189 static char* cpoint_type;
 190 module_param(cpoint_type, charp, 0444);
 191 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 192                                 "hitting the crash point");
 193
 194 static int cpoint_count = DEFAULT_COUNT;
 195 module_param(cpoint_count, int, 0644);
 196 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 197                                 "crash point is to be hit to trigger action");
 198
 199
 200 /* Return the crashtype number or NULL if the name is invalid */
 201 static const struct crashtype *find_crashtype(const char *name)
 202 {
 203         int i;
 204
 205         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 206                 if (!strcmp(name, crashtypes[i].name))
 207                         return &crashtypes[i];
 208         }
 209
 210         return NULL;
 211 }
 212
 213 /*
 214  * This is forced noinline just so it distinctly shows up in the stackdump
 215  * which makes validation of expected lkdtm crashes easier.
 216  */
 217 static noinline void lkdtm_do_action(const struct crashtype *crashtype)
 218 {
 219         if (WARN_ON(!crashtype || !crashtype->func))
 220                 return;
 221         crashtype->func();
 222 }
 223
 224 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 225                                  const struct crashtype *crashtype)
 226 {
 227         int ret;
 228
 229         /* If this doesn't have a symbol, just call immediately. */
 230         if (!crashpoint->kprobe.symbol_name) {
 231                 lkdtm_do_action(crashtype);
 232                 return 0;
 233         }
 234
 235         if (lkdtm_kprobe != NULL)
 236                 unregister_kprobe(lkdtm_kprobe);
 237
 238         lkdtm_crashpoint = crashpoint;
 239         lkdtm_crashtype = crashtype;
 240         lkdtm_kprobe = &crashpoint->kprobe;
 241         ret = register_kprobe(lkdtm_kprobe);
 242         if (ret < 0) {
 243                 pr_info("Couldn't register kprobe %s\n",
 244                         crashpoint->kprobe.symbol_name);
 245                 lkdtm_kprobe = NULL;
 246                 lkdtm_crashpoint = NULL;
 247                 lkdtm_crashtype = NULL;
 248         }
 249
 250         return ret;
 251 }
 252
 253 #ifdef CONFIG_KPROBES
 254 /* Global crash counter and spinlock. */
 255 static int crash_count = DEFAULT_COUNT;
 256 static DEFINE_SPINLOCK(crash_count_lock);
 257
 258 /* Called by kprobe entry points. */
 259 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 260 {
 261         unsigned long flags;
 262         bool do_it = false;
 263
 264         if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
 265                 return 0;
 266
 267         spin_lock_irqsave(&crash_count_lock, flags);
 268         crash_count--;
 269         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 270                 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
 271
 272         if (crash_count == 0) {
 273                 do_it = true;
 274                 crash_count = cpoint_count;
 275         }
 276         spin_unlock_irqrestore(&crash_count_lock, flags);
 277
 278         if (do_it)
 279                 lkdtm_do_action(lkdtm_crashtype);
 280
 281         return 0;
 282 }
 283
 284 static ssize_t lkdtm_debugfs_entry(struct file *f,
 285                                    const char __user *user_buf,
 286                                    size_t count, loff_t *off)
 287 {
 288         struct crashpoint *crashpoint = file_inode(f)->i_private;
 289         const struct crashtype *crashtype = NULL;
 290         char *buf;
 291         int err;
 292
 293         if (count >= PAGE_SIZE)
 294                 return -EINVAL;
 295
 296         buf = (char *)__get_free_page(GFP_KERNEL);
 297         if (!buf)
 298                 return -ENOMEM;
 299         if (copy_from_user(buf, user_buf, count)) {
 300                 free_page((unsigned long) buf);
 301                 return -EFAULT;
 302         }
 303         /* NULL-terminate and remove enter */
 304         buf[count] = '\0';
 305         strim(buf);
 306
 307         crashtype = find_crashtype(buf);
 308         free_page((unsigned long)buf);
 309
 310         if (!crashtype)
 311                 return -EINVAL;
 312
 313         err = lkdtm_register_cpoint(crashpoint, crashtype);
 314         if (err < 0)
 315                 return err;
 316
 317         *off += count;
 318
 319         return count;
 320 }
 321 #endif
 322
 323 /* Generic read callback that just prints out the available crash types */
 324 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 325                 size_t count, loff_t *off)
 326 {
 327         char *buf;
 328         int i, n, out;
 329
 330         buf = (char *)__get_free_page(GFP_KERNEL);
 331         if (buf == NULL)
 332                 return -ENOMEM;
 333
 334         n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
 335         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 336                 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
 337                               crashtypes[i].name);
 338         }
 339         buf[n] = '\0';
 340
 341         out = simple_read_from_buffer(user_buf, count, off,
 342                                       buf, n);
 343         free_page((unsigned long) buf);
 344
 345         return out;
 346 }
 347
 348 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 349 {
 350         return 0;
 351 }
 352
 353 /* Special entry to just crash directly. Available without KPROBEs */
 354 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 355                 size_t count, loff_t *off)
 356 {
 357         const struct crashtype *crashtype;
 358         char *buf;
 359
 360         if (count >= PAGE_SIZE)
 361                 return -EINVAL;
 362         if (count < 1)
 363                 return -EINVAL;
 364
 365         buf = (char *)__get_free_page(GFP_KERNEL);
 366         if (!buf)
 367                 return -ENOMEM;
 368         if (copy_from_user(buf, user_buf, count)) {
 369                 free_page((unsigned long) buf);
 370                 return -EFAULT;
 371         }
 372         /* NULL-terminate and remove enter */
 373         buf[count] = '\0';
 374         strim(buf);
 375
 376         crashtype = find_crashtype(buf);
 377         free_page((unsigned long) buf);
 378         if (!crashtype)
 379                 return -EINVAL;
 380
 381         pr_info("Performing direct entry %s\n", crashtype->name);
 382         lkdtm_do_action(crashtype);
 383         *off += count;
 384
 385         return count;
 386 }
 387
 388 static struct dentry *lkdtm_debugfs_root;
 389
 390 static int __init lkdtm_module_init(void)
 391 {
 392         struct crashpoint *crashpoint = NULL;
 393         const struct crashtype *crashtype = NULL;
 394         int ret;
 395         int i;
 396
 397         /* Neither or both of these need to be set */
 398         if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
 399                 pr_err("Need both cpoint_type and cpoint_name or neither\n");
 400                 return -EINVAL;
 401         }
 402
 403         if (cpoint_type) {
 404                 crashtype = find_crashtype(cpoint_type);
 405                 if (!crashtype) {
 406                         pr_err("Unknown crashtype '%s'\n", cpoint_type);
 407                         return -EINVAL;
 408                 }
 409         }
 410
 411         if (cpoint_name) {
 412                 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 413                         if (!strcmp(cpoint_name, crashpoints[i].name))
 414                                 crashpoint = &crashpoints[i];
 415                 }
 416
 417                 /* Refuse unknown crashpoints. */
 418                 if (!crashpoint) {
 419                         pr_err("Invalid crashpoint %s\n", cpoint_name);
 420                         return -EINVAL;
 421                 }
 422         }
 423
 424 #ifdef CONFIG_KPROBES
 425         /* Set crash count. */
 426         crash_count = cpoint_count;
 427 #endif
 428
 429         /* Handle test-specific initialization. */
 430         lkdtm_bugs_init(&recur_count);
 431         lkdtm_perms_init();
 432         lkdtm_usercopy_init();
 433         lkdtm_heap_init();
 434
 435         /* Register debugfs interface */
 436         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 437
 438         /* Install debugfs trigger files. */
 439         for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 440                 struct crashpoint *cur = &crashpoints[i];
 441
 442                 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
 443                                     &cur->fops);
 444         }
 445
 446         /* Install crashpoint if one was selected. */
 447         if (crashpoint) {
 448                 ret = lkdtm_register_cpoint(crashpoint, crashtype);
 449                 if (ret < 0) {
 450                         pr_info("Invalid crashpoint %s\n", crashpoint->name);
 451                         goto out_err;
 452                 }
 453                 pr_info("Crash point %s of type %s registered\n",
 454                         crashpoint->name, cpoint_type);
 455         } else {
 456                 pr_info("No crash points registered, enable through debugfs\n");
 457         }
 458
 459         return 0;
 460
 461 out_err:
 462         debugfs_remove_recursive(lkdtm_debugfs_root);
 463         return ret;
 464 }
 465
 466 static void __exit lkdtm_module_exit(void)
 467 {
 468         debugfs_remove_recursive(lkdtm_debugfs_root);
 469
 470         /* Handle test-specific clean-up. */
 471         lkdtm_heap_exit();
 472         lkdtm_usercopy_exit();
 473
 474         if (lkdtm_kprobe != NULL)
 475                 unregister_kprobe(lkdtm_kprobe);
 476
 477         pr_info("Crash point unregistered\n");
 478 }
 479
 480 module_init(lkdtm_module_init);
 481 module_exit(lkdtm_module_exit);
 482
 483 MODULE_LICENSE("GPL");
 484 MODULE_DESCRIPTION("Kernel crash testing module");