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