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 #include <linux/utsname.h>
  30
  31 #define DEFAULT_COUNT 10
  32
  33 static int lkdtm_debugfs_open(struct inode *inode, struct file *file);
  34 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
  35                 size_t count, loff_t *off);
  36 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
  37                             size_t count, loff_t *off);
  38
  39 #ifdef CONFIG_KPROBES
  40 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
  41 static ssize_t lkdtm_debugfs_entry(struct file *f,
  42                                    const char __user *user_buf,
  43                                    size_t count, loff_t *off);
  44 # define CRASHPOINT_KPROBE(_symbol)                             \
  45                 .kprobe = {                                     \
  46                         .symbol_name = (_symbol),               \
  47                         .pre_handler = lkdtm_kprobe_handler,    \
  48                 },
  49 # define CRASHPOINT_WRITE(_symbol)                              \
  50                 (_symbol) ? lkdtm_debugfs_entry : direct_entry
  51 #else
  52 # define CRASHPOINT_KPROBE(_symbol)
  53 # define CRASHPOINT_WRITE(_symbol)              direct_entry
  54 #endif
  55
  56 /* Crash points */
  57 struct crashpoint {
  58         const char *name;
  59         const struct file_operations fops;
  60         struct kprobe kprobe;
  61 };
  62
  63 #define CRASHPOINT(_name, _symbol)                              \
  64         {                                                       \
  65                 .name = _name,                                  \
  66                 .fops = {                                       \
  67                         .read   = lkdtm_debugfs_read,           \
  68                         .llseek = generic_file_llseek,          \
  69                         .open   = lkdtm_debugfs_open,           \
  70                         .write  = CRASHPOINT_WRITE(_symbol)     \
  71                 },                                              \
  72                 CRASHPOINT_KPROBE(_symbol)                      \
  73         }
  74
  75 /* Define the possible places where we can trigger a crash point. */
  76 static struct crashpoint crashpoints[] = {
  77         CRASHPOINT("DIRECT",             NULL),
  78 #ifdef CONFIG_KPROBES
  79         CRASHPOINT("INT_HARDWARE_ENTRY", "do_IRQ"),
  80         CRASHPOINT("INT_HW_IRQ_EN",      "handle_irq_event"),
  81         CRASHPOINT("INT_TASKLET_ENTRY",  "tasklet_action"),
  82         CRASHPOINT("FS_SUBMIT_BH",               "submit_bh"),
  83         CRASHPOINT("MEM_SWAPOUT",        "shrink_inactive_list"),
  84         CRASHPOINT("TIMERADD",           "hrtimer_start"),
  85         CRASHPOINT("SCSI_QUEUE_RQ",      "scsi_queue_rq"),
  86 #endif
  87 };
  88
  89 /* List of possible types for crashes that can be triggered. */
  90 static const struct crashtype_category *crashtype_categories[] = {
  91         &bugs_crashtypes,
  92         &heap_crashtypes,
  93         &perms_crashtypes,
  94         &refcount_crashtypes,
  95         &usercopy_crashtypes,
  96         &stackleak_crashtypes,
  97         &cfi_crashtypes,
  98         &fortify_crashtypes,
  99 #ifdef CONFIG_PPC_64S_HASH_MMU
 100         &powerpc_crashtypes,
 101 #endif
 102 };
 103
 104 /* Global kprobe entry and crashtype. */
 105 static struct kprobe *lkdtm_kprobe;
 106 static struct crashpoint *lkdtm_crashpoint;
 107 static const struct crashtype *lkdtm_crashtype;
 108
 109 /* Module parameters */
 110 static int recur_count = -1;
 111 module_param(recur_count, int, 0644);
 112 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 113
 114 static char* cpoint_name;
 115 module_param(cpoint_name, charp, 0444);
 116 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 117
 118 static char* cpoint_type;
 119 module_param(cpoint_type, charp, 0444);
 120 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 121                                 "hitting the crash point");
 122
 123 static int cpoint_count = DEFAULT_COUNT;
 124 module_param(cpoint_count, int, 0644);
 125 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 126                                 "crash point is to be hit to trigger action");
 127
 128 /*
 129  * For test debug reporting when CI systems provide terse summaries.
 130  * TODO: Remove this once reasonable reporting exists in most CI systems:
 131  * https://lore.kernel.org/lkml/CAHk-=wiFvfkoFixTapvvyPMN9pq5G-+Dys2eSyBa1vzDGAO5+A@mail.gmail.com
 132  */
 133 char *lkdtm_kernel_info;
 134
 135 /* Return the crashtype number or NULL if the name is invalid */
 136 static const struct crashtype *find_crashtype(const char *name)
 137 {
 138         int cat, idx;
 139
 140         for (cat = 0; cat < ARRAY_SIZE(crashtype_categories); cat++) {
 141                 for (idx = 0; idx < crashtype_categories[cat]->len; idx++) {
 142                         struct crashtype *crashtype;
 143
 144                         crashtype = &crashtype_categories[cat]->crashtypes[idx];
 145                         if (!strcmp(name, crashtype->name))
 146                                 return crashtype;
 147                 }
 148         }
 149
 150         return NULL;
 151 }
 152
 153 /*
 154  * This is forced noinline just so it distinctly shows up in the stackdump
 155  * which makes validation of expected lkdtm crashes easier.
 156  *
 157  * NOTE: having a valid return value helps prevent the compiler from doing
 158  * tail call optimizations and taking this out of the stack trace.
 159  */
 160 static noinline int lkdtm_do_action(const struct crashtype *crashtype)
 161 {
 162         if (WARN_ON(!crashtype || !crashtype->func))
 163                 return -EINVAL;
 164         crashtype->func();
 165
 166         return 0;
 167 }
 168
 169 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
 170                                  const struct crashtype *crashtype)
 171 {
 172         int ret;
 173
 174         /* If this doesn't have a symbol, just call immediately. */
 175         if (!crashpoint->kprobe.symbol_name)
 176                 return lkdtm_do_action(crashtype);
 177
 178         if (lkdtm_kprobe != NULL)
 179                 unregister_kprobe(lkdtm_kprobe);
 180
 181         lkdtm_crashpoint = crashpoint;
 182         lkdtm_crashtype = crashtype;
 183         lkdtm_kprobe = &crashpoint->kprobe;
 184         ret = register_kprobe(lkdtm_kprobe);
 185         if (ret < 0) {
 186                 pr_info("Couldn't register kprobe %s\n",
 187                         crashpoint->kprobe.symbol_name);
 188                 lkdtm_kprobe = NULL;
 189                 lkdtm_crashpoint = NULL;
 190                 lkdtm_crashtype = NULL;
 191         }
 192
 193         return ret;
 194 }
 195
 196 #ifdef CONFIG_KPROBES
 197 /* Global crash counter and spinlock. */
 198 static int crash_count = DEFAULT_COUNT;
 199 static DEFINE_SPINLOCK(crash_count_lock);
 200
 201 /* Called by kprobe entry points. */
 202 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
 203 {
 204         unsigned long flags;
 205         bool do_it = false;
 206
 207         if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
 208                 return 0;
 209
 210         spin_lock_irqsave(&crash_count_lock, flags);
 211         crash_count--;
 212         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 213                 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
 214
 215         if (crash_count == 0) {
 216                 do_it = true;
 217                 crash_count = cpoint_count;
 218         }
 219         spin_unlock_irqrestore(&crash_count_lock, flags);
 220
 221         if (do_it)
 222                 return lkdtm_do_action(lkdtm_crashtype);
 223
 224         return 0;
 225 }
 226
 227 static ssize_t lkdtm_debugfs_entry(struct file *f,
 228                                    const char __user *user_buf,
 229                                    size_t count, loff_t *off)
 230 {
 231         struct crashpoint *crashpoint = file_inode(f)->i_private;
 232         const struct crashtype *crashtype = NULL;
 233         char *buf;
 234         int err;
 235
 236         if (count >= PAGE_SIZE)
 237                 return -EINVAL;
 238
 239         buf = (char *)__get_free_page(GFP_KERNEL);
 240         if (!buf)
 241                 return -ENOMEM;
 242         if (copy_from_user(buf, user_buf, count)) {
 243                 free_page((unsigned long) buf);
 244                 return -EFAULT;
 245         }
 246         /* NULL-terminate and remove enter */
 247         buf[count] = '\0';
 248         strim(buf);
 249
 250         crashtype = find_crashtype(buf);
 251         free_page((unsigned long)buf);
 252
 253         if (!crashtype)
 254                 return -EINVAL;
 255
 256         err = lkdtm_register_cpoint(crashpoint, crashtype);
 257         if (err < 0)
 258                 return err;
 259
 260         *off += count;
 261
 262         return count;
 263 }
 264 #endif
 265
 266 /* Generic read callback that just prints out the available crash types */
 267 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 268                 size_t count, loff_t *off)
 269 {
 270         int n, cat, idx;
 271         ssize_t out;
 272         char *buf;
 273
 274         buf = (char *)__get_free_page(GFP_KERNEL);
 275         if (buf == NULL)
 276                 return -ENOMEM;
 277
 278         n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
 279
 280         for (cat = 0; cat < ARRAY_SIZE(crashtype_categories); cat++) {
 281                 for (idx = 0; idx < crashtype_categories[cat]->len; idx++) {
 282                         struct crashtype *crashtype;
 283
 284                         crashtype = &crashtype_categories[cat]->crashtypes[idx];
 285                         n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
 286                                       crashtype->name);
 287                 }
 288         }
 289         buf[n] = '\0';
 290
 291         out = simple_read_from_buffer(user_buf, count, off,
 292                                       buf, n);
 293         free_page((unsigned long) buf);
 294
 295         return out;
 296 }
 297
 298 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 299 {
 300         return 0;
 301 }
 302
 303 /* Special entry to just crash directly. Available without KPROBEs */
 304 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 305                 size_t count, loff_t *off)
 306 {
 307         const struct crashtype *crashtype;
 308         char *buf;
 309         int err;
 310
 311         if (count >= PAGE_SIZE)
 312                 return -EINVAL;
 313         if (count < 1)
 314                 return -EINVAL;
 315
 316         buf = (char *)__get_free_page(GFP_KERNEL);
 317         if (!buf)
 318                 return -ENOMEM;
 319         if (copy_from_user(buf, user_buf, count)) {
 320                 free_page((unsigned long) buf);
 321                 return -EFAULT;
 322         }
 323         /* NULL-terminate and remove enter */
 324         buf[count] = '\0';
 325         strim(buf);
 326
 327         crashtype = find_crashtype(buf);
 328         free_page((unsigned long) buf);
 329         if (!crashtype)
 330                 return -EINVAL;
 331
 332         pr_info("Performing direct entry %s\n", crashtype->name);
 333         err = lkdtm_do_action(crashtype);
 334         *off += count;
 335
 336         if (err)
 337                 return err;
 338         return count;
 339 }
 340
 341 #ifndef MODULE
 342 /*
 343  * To avoid needing to export parse_args(), just don't use this code
 344  * when LKDTM is built as a module.
 345  */
 346 struct check_cmdline_args {
 347         const char *param;
 348         int value;
 349 };
 350
 351 static int lkdtm_parse_one(char *param, char *val,
 352                            const char *unused, void *arg)
 353 {
 354         struct check_cmdline_args *args = arg;
 355
 356         /* short circuit if we already found a value. */
 357         if (args->value != -ESRCH)
 358                 return 0;
 359         if (strncmp(param, args->param, strlen(args->param)) == 0) {
 360                 bool bool_result;
 361                 int ret;
 362
 363                 ret = kstrtobool(val, &bool_result);
 364                 if (ret == 0)
 365                         args->value = bool_result;
 366         }
 367         return 0;
 368 }
 369
 370 int lkdtm_check_bool_cmdline(const char *param)
 371 {
 372         char *command_line;
 373         struct check_cmdline_args args = {
 374                 .param = param,
 375                 .value = -ESRCH,
 376         };
 377
 378         command_line = kstrdup(saved_command_line, GFP_KERNEL);
 379         if (!command_line)
 380                 return -ENOMEM;
 381
 382         parse_args("Setting sysctl args", command_line,
 383                    NULL, 0, -1, -1, &args, lkdtm_parse_one);
 384
 385         kfree(command_line);
 386
 387         return args.value;
 388 }
 389 #endif
 390
 391 static struct dentry *lkdtm_debugfs_root;
 392
 393 static int __init lkdtm_module_init(void)
 394 {
 395         struct crashpoint *crashpoint = NULL;
 396         const struct crashtype *crashtype = NULL;
 397         int ret;
 398         int i;
 399
 400         /* Neither or both of these need to be set */
 401         if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
 402                 pr_err("Need both cpoint_type and cpoint_name or neither\n");
 403                 return -EINVAL;
 404         }
 405
 406         if (cpoint_type) {
 407                 crashtype = find_crashtype(cpoint_type);
 408                 if (!crashtype) {
 409                         pr_err("Unknown crashtype '%s'\n", cpoint_type);
 410                         return -EINVAL;
 411                 }
 412         }
 413
 414         if (cpoint_name) {
 415                 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 416                         if (!strcmp(cpoint_name, crashpoints[i].name))
 417                                 crashpoint = &crashpoints[i];
 418                 }
 419
 420                 /* Refuse unknown crashpoints. */
 421                 if (!crashpoint) {
 422                         pr_err("Invalid crashpoint %s\n", cpoint_name);
 423                         return -EINVAL;
 424                 }
 425         }
 426
 427 #ifdef CONFIG_KPROBES
 428         /* Set crash count. */
 429         crash_count = cpoint_count;
 430 #endif
 431
 432         /* Common initialization. */
 433         lkdtm_kernel_info = kasprintf(GFP_KERNEL, "kernel (%s %s)",
 434                                       init_uts_ns.name.release,
 435                                       init_uts_ns.name.machine);
 436
 437         /* Handle test-specific initialization. */
 438         lkdtm_bugs_init(&recur_count);
 439         lkdtm_perms_init();
 440         lkdtm_usercopy_init();
 441         lkdtm_heap_init();
 442
 443         /* Register debugfs interface */
 444         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 445
 446         /* Install debugfs trigger files. */
 447         for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
 448                 struct crashpoint *cur = &crashpoints[i];
 449
 450                 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
 451                                     &cur->fops);
 452         }
 453
 454         /* Install crashpoint if one was selected. */
 455         if (crashpoint) {
 456                 ret = lkdtm_register_cpoint(crashpoint, crashtype);
 457                 if (ret < 0) {
 458                         pr_info("Invalid crashpoint %s\n", crashpoint->name);
 459                         goto out_err;
 460                 }
 461                 pr_info("Crash point %s of type %s registered\n",
 462                         crashpoint->name, cpoint_type);
 463         } else {
 464                 pr_info("No crash points registered, enable through debugfs\n");
 465         }
 466
 467         return 0;
 468
 469 out_err:
 470         debugfs_remove_recursive(lkdtm_debugfs_root);
 471         return ret;
 472 }
 473
 474 static void __exit lkdtm_module_exit(void)
 475 {
 476         debugfs_remove_recursive(lkdtm_debugfs_root);
 477
 478         /* Handle test-specific clean-up. */
 479         lkdtm_heap_exit();
 480         lkdtm_usercopy_exit();
 481
 482         if (lkdtm_kprobe != NULL)
 483                 unregister_kprobe(lkdtm_kprobe);
 484
 485         kfree(lkdtm_kernel_info);
 486
 487         pr_info("Crash point unregistered\n");
 488 }
 489
 490 module_init(lkdtm_module_init);
 491 module_exit(lkdtm_module_exit);
 492
 493 MODULE_LICENSE("GPL");
 494 MODULE_DESCRIPTION("Kernel crash testing module");