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(CORRUPT_LIST_ADD),
 114         CRASHTYPE(CORRUPT_LIST_DEL),
 115         CRASHTYPE(CORRUPT_USER_DS),
 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(OVERWRITE_ALLOCATION),
 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_FREE_DOUBLE),
 127         CRASHTYPE(SLAB_FREE_CROSS),
 128         CRASHTYPE(SLAB_FREE_PAGE),
 129         CRASHTYPE(SOFTLOCKUP),
 130         CRASHTYPE(HARDLOCKUP),
 131         CRASHTYPE(SPINLOCKUP),
 132         CRASHTYPE(HUNG_TASK),
 133         CRASHTYPE(OVERFLOW_SIGNED),
 134         CRASHTYPE(OVERFLOW_UNSIGNED),
 135         CRASHTYPE(ARRAY_BOUNDS),
 136         CRASHTYPE(EXEC_DATA),
 137         CRASHTYPE(EXEC_STACK),
 138         CRASHTYPE(EXEC_KMALLOC),
 139         CRASHTYPE(EXEC_VMALLOC),
 140         CRASHTYPE(EXEC_RODATA),
 141         CRASHTYPE(EXEC_USERSPACE),
 142         CRASHTYPE(EXEC_NULL),
 143         CRASHTYPE(ACCESS_USERSPACE),
 144         CRASHTYPE(ACCESS_NULL),
 145         CRASHTYPE(WRITE_RO),
 146         CRASHTYPE(WRITE_RO_AFTER_INIT),
 147         CRASHTYPE(WRITE_KERN),
 148         CRASHTYPE(REFCOUNT_INC_OVERFLOW),
 149         CRASHTYPE(REFCOUNT_ADD_OVERFLOW),
 150         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_OVERFLOW),
 151         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_OVERFLOW),
 152         CRASHTYPE(REFCOUNT_DEC_ZERO),
 153         CRASHTYPE(REFCOUNT_DEC_NEGATIVE),
 154         CRASHTYPE(REFCOUNT_DEC_AND_TEST_NEGATIVE),
 155         CRASHTYPE(REFCOUNT_SUB_AND_TEST_NEGATIVE),
 156         CRASHTYPE(REFCOUNT_INC_ZERO),
 157         CRASHTYPE(REFCOUNT_ADD_ZERO),
 158         CRASHTYPE(REFCOUNT_INC_SATURATED),
 159         CRASHTYPE(REFCOUNT_DEC_SATURATED),
 160         CRASHTYPE(REFCOUNT_ADD_SATURATED),
 161         CRASHTYPE(REFCOUNT_INC_NOT_ZERO_SATURATED),
 162         CRASHTYPE(REFCOUNT_ADD_NOT_ZERO_SATURATED),
 163         CRASHTYPE(REFCOUNT_DEC_AND_TEST_SATURATED),
 164         CRASHTYPE(REFCOUNT_SUB_AND_TEST_SATURATED),
 165         CRASHTYPE(REFCOUNT_TIMING),
 166         CRASHTYPE(ATOMIC_TIMING),
 167         CRASHTYPE(USERCOPY_HEAP_SIZE_TO),
 168         CRASHTYPE(USERCOPY_HEAP_SIZE_FROM),
 169         CRASHTYPE(USERCOPY_HEAP_WHITELIST_TO),
 170         CRASHTYPE(USERCOPY_HEAP_WHITELIST_FROM),
 171         CRASHTYPE(USERCOPY_STACK_FRAME_TO),
 172         CRASHTYPE(USERCOPY_STACK_FRAME_FROM),
 173         CRASHTYPE(USERCOPY_STACK_BEYOND),
 174         CRASHTYPE(USERCOPY_KERNEL),
 175         CRASHTYPE(USERCOPY_KERNEL_DS),
 176         CRASHTYPE(STACKLEAK_ERASING),
 177         CRASHTYPE(CFI_FORWARD_PROTO),
 178 #ifdef CONFIG_X86_32
 179         CRASHTYPE(DOUBLE_FAULT),
 180 #endif
 181 };
 182
 183
 184 /* Global kprobe entry and crashtype. */
 185 static struct kprobe *lkdtm_kprobe;
 186 static struct crashpoint *lkdtm_crashpoint;
 187 static const struct crashtype *lkdtm_crashtype;
 188
 189 /* Module parameters */
 190 static int recur_count = -1;
 191 module_param(recur_count, int, 0644);
 192 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 193
 194 static char* cpoint_name;
 195 module_param(cpoint_name, charp, 0444);
 196 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 197
 198 static char* cpoint_type;
 199 module_param(cpoint_type, charp, 0444);
 200 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 201                                 "hitting the crash point");
 202
 203 static int cpoint_count = DEFAULT_COUNT;
 204 module_param(cpoint_count, int, 0644);
 205 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 206                                 "crash point is to be hit to trigger action");
 207
 208
 209 /* Return the crashtype number or NULL if the name is invalid */
 210 static const struct crashtype *find_crashtype(const char *name)
 211 {
 212         int i;
 213
 214         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 215                 if (!strcmp(name, crashtypes[i].name))
 216                         return &crashtypes[i];
 217         }
 218
 219         return NULL;
 220 }
 221
 222 /*
 223  * This is forced noinline just so it distinctly shows up in the stackdump
 224  * which makes validation of expected lkdtm crashes easier.
 225  */
 226 static noinline void lkdtm_do_action(const struct crashtype *crashtype)
 227 {
 228         if (WARN_ON(!crashtype || !crashtype->func))
 229                 return;
 230         crashtype->func();
 231 }
 232
 233 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 234                                  const struct crashtype *crashtype)
 235 {
 236         int ret;
 237
 238         /* If this doesn't have a symbol, just call immediately. */
 239         if (!crashpoint->kprobe.symbol_name) {
 240                 lkdtm_do_action(crashtype);
 241                 return 0;
 242         }
 243
 244         if (lkdtm_kprobe != NULL)
 245                 unregister_kprobe(lkdtm_kprobe);
 246
 247         lkdtm_crashpoint = crashpoint;
 248         lkdtm_crashtype = crashtype;
 249         lkdtm_kprobe = &crashpoint->kprobe;
 250         ret = register_kprobe(lkdtm_kprobe);
 251         if (ret < 0) {
 252                 pr_info("Couldn't register kprobe %s\n",
 253                         crashpoint->kprobe.symbol_name);
 254                 lkdtm_kprobe = NULL;
 255                 lkdtm_crashpoint = NULL;
 256                 lkdtm_crashtype = NULL;
 257         }
 258
 259         return ret;
 260 }
 261
 262 #ifdef CONFIG_KPROBES
 263 /* Global crash counter and spinlock. */
 264 static int crash_count = DEFAULT_COUNT;
 265 static DEFINE_SPINLOCK(crash_count_lock);
 266
 267 /* Called by kprobe entry points. */
 268 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 269 {
 270         unsigned long flags;
 271         bool do_it = false;
 272
 273         if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
 274                 return 0;
 275
 276         spin_lock_irqsave(&crash_count_lock, flags);
 277         crash_count--;
 278         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 279                 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
 280
 281         if (crash_count == 0) {
 282                 do_it = true;
 283                 crash_count = cpoint_count;
 284         }
 285         spin_unlock_irqrestore(&crash_count_lock, flags);
 286
 287         if (do_it)
 288                 lkdtm_do_action(lkdtm_crashtype);
 289
 290         return 0;
 291 }
 292
 293 static ssize_t lkdtm_debugfs_entry(struct file *f,
 294                                    const char __user *user_buf,
 295                                    size_t count, loff_t *off)
 296 {
 297         struct crashpoint *crashpoint = file_inode(f)->i_private;
 298         const struct crashtype *crashtype = NULL;
 299         char *buf;
 300         int err;
 301
 302         if (count >= PAGE_SIZE)
 303                 return -EINVAL;
 304
 305         buf = (char *)__get_free_page(GFP_KERNEL);
 306         if (!buf)
 307                 return -ENOMEM;
 308         if (copy_from_user(buf, user_buf, count)) {
 309                 free_page((unsigned long) buf);
 310                 return -EFAULT;
 311         }
 312         /* NULL-terminate and remove enter */
 313         buf[count] = '\0';
 314         strim(buf);
 315
 316         crashtype = find_crashtype(buf);
 317         free_page((unsigned long)buf);
 318
 319         if (!crashtype)
 320                 return -EINVAL;
 321
 322         err = lkdtm_register_cpoint(crashpoint, crashtype);
 323         if (err < 0)
 324                 return err;
 325
 326         *off += count;
 327
 328         return count;
 329 }
 330 #endif
 331
 332 /* Generic read callback that just prints out the available crash types */
 333 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 334                 size_t count, loff_t *off)
 335 {
 336         char *buf;
 337         int i, n, out;
 338
 339         buf = (char *)__get_free_page(GFP_KERNEL);
 340         if (buf == NULL)
 341                 return -ENOMEM;
 342
 343         n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
 344         for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
 345                 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
 346                               crashtypes[i].name);
 347         }
 348         buf[n] = '\0';
 349
 350         out = simple_read_from_buffer(user_buf, count, off,
 351                                       buf, n);
 352         free_page((unsigned long) buf);
 353
 354         return out;
 355 }
 356
 357 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 358 {
 359         return 0;
 360 }
 361
 362 /* Special entry to just crash directly. Available without KPROBEs */
 363 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 364                 size_t count, loff_t *off)
 365 {
 366         const struct crashtype *crashtype;
 367         char *buf;
 368
 369         if (count >= PAGE_SIZE)
 370                 return -EINVAL;
 371         if (count < 1)
 372                 return -EINVAL;
 373
 374         buf = (char *)__get_free_page(GFP_KERNEL);
 375         if (!buf)
 376                 return -ENOMEM;
 377         if (copy_from_user(buf, user_buf, count)) {
 378                 free_page((unsigned long) buf);
 379                 return -EFAULT;
 380         }
 381         /* NULL-terminate and remove enter */
 382         buf[count] = '\0';
 383         strim(buf);
 384
 385         crashtype = find_crashtype(buf);
 386         free_page((unsigned long) buf);
 387         if (!crashtype)
 388                 return -EINVAL;
 389
 390         pr_info("Performing direct entry %s\n", crashtype->name);
 391         lkdtm_do_action(crashtype);
 392         *off += count;
 393
 394         return count;
 395 }
 396
 397 static struct dentry *lkdtm_debugfs_root;
 398
 399 static int __init lkdtm_module_init(void)
 400 {
 401         struct crashpoint *crashpoint = NULL;
 402         const struct crashtype *crashtype = NULL;
 403         int ret;
 404         int i;
 405
 406         /* Neither or both of these need to be set */
 407         if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
 408                 pr_err("Need both cpoint_type and cpoint_name or neither\n");
 409                 return -EINVAL;
 410         }
 411
 412         if (cpoint_type) {
 413                 crashtype = find_crashtype(cpoint_type);
 414                 if (!crashtype) {
 415                         pr_err("Unknown crashtype '%s'\n", cpoint_type);
 416                         return -EINVAL;
 417                 }
 418         }
 419
 420         if (cpoint_name) {
 421                 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 422                         if (!strcmp(cpoint_name, crashpoints[i].name))
 423                                 crashpoint = &crashpoints[i];
 424                 }
 425
 426                 /* Refuse unknown crashpoints. */
 427                 if (!crashpoint) {
 428                         pr_err("Invalid crashpoint %s\n", cpoint_name);
 429                         return -EINVAL;
 430                 }
 431         }
 432
 433 #ifdef CONFIG_KPROBES
 434         /* Set crash count. */
 435         crash_count = cpoint_count;
 436 #endif
 437
 438         /* Handle test-specific initialization. */
 439         lkdtm_bugs_init(&recur_count);
 440         lkdtm_perms_init();
 441         lkdtm_usercopy_init();
 442         lkdtm_heap_init();
 443
 444         /* Register debugfs interface */
 445         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 446
 447         /* Install debugfs trigger files. */
 448         for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 449                 struct crashpoint *cur = &crashpoints[i];
 450
 451                 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
 452                                     &cur->fops);
 453         }
 454
 455         /* Install crashpoint if one was selected. */
 456         if (crashpoint) {
 457                 ret = lkdtm_register_cpoint(crashpoint, crashtype);
 458                 if (ret < 0) {
 459                         pr_info("Invalid crashpoint %s\n", crashpoint->name);
 460                         goto out_err;
 461                 }
 462                 pr_info("Crash point %s of type %s registered\n",
 463                         crashpoint->name, cpoint_type);
 464         } else {
 465                 pr_info("No crash points registered, enable through debugfs\n");
 466         }
 467
 468         return 0;
 469
 470 out_err:
 471         debugfs_remove_recursive(lkdtm_debugfs_root);
 472         return ret;
 473 }
 474
 475 static void __exit lkdtm_module_exit(void)
 476 {
 477         debugfs_remove_recursive(lkdtm_debugfs_root);
 478
 479         /* Handle test-specific clean-up. */
 480         lkdtm_heap_exit();
 481         lkdtm_usercopy_exit();
 482
 483         if (lkdtm_kprobe != NULL)
 484                 unregister_kprobe(lkdtm_kprobe);
 485
 486         pr_info("Crash point unregistered\n");
 487 }
 488
 489 module_init(lkdtm_module_init);
 490 module_exit(lkdtm_module_exit);
 491
 492 MODULE_LICENSE("GPL");
 493 MODULE_DESCRIPTION("Kernel crash testing module");