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