drivers/misc/lkdtm.c

   1 /*
   2  * Kprobe module for testing crash dumps
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2006
  19  *
  20  * Author: Ankita Garg <ankita@in.ibm.com>
  21  *
  22  * This module induces system failures at predefined crashpoints to
  23  * evaluate the reliability of crash dumps obtained using different dumping
  24  * solutions.
  25  *
  26  * It is adapted from the Linux Kernel Dump Test Tool by
  27  * Fernando Luis Vazquez Cao <http://lkdtt.sourceforge.net>
  28  *
  29  * Debugfs support added by Simon Kagstrom <simon.kagstrom@netinsight.net>
  30  *
  31  * See Documentation/fault-injection/provoke-crashes.txt for instructions
  32  */
  33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  34
  35 #include <linux/kernel.h>
  36 #include <linux/fs.h>
  37 #include <linux/module.h>
  38 #include <linux/buffer_head.h>
  39 #include <linux/kprobes.h>
  40 #include <linux/list.h>
  41 #include <linux/init.h>
  42 #include <linux/interrupt.h>
  43 #include <linux/hrtimer.h>
  44 #include <linux/slab.h>
  45 #include <scsi/scsi_cmnd.h>
  46 #include <linux/debugfs.h>
  47 #include <linux/vmalloc.h>
  48 #include <linux/mman.h>
  49 #include <asm/cacheflush.h>
  50
  51 #ifdef CONFIG_IDE
  52 #include <linux/ide.h>
  53 #endif
  54
  55 /*
  56  * Make sure our attempts to over run the kernel stack doesn't trigger
  57  * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we
  58  * recurse past the end of THREAD_SIZE by default.
  59  */
  60 #if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0)
  61 #define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2)
  62 #else
  63 #define REC_STACK_SIZE (THREAD_SIZE / 8)
  64 #endif
  65 #define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2)
  66
  67 #define DEFAULT_COUNT 10
  68 #define EXEC_SIZE 64
  69
  70 enum cname {
  71         CN_INVALID,
  72         CN_INT_HARDWARE_ENTRY,
  73         CN_INT_HW_IRQ_EN,
  74         CN_INT_TASKLET_ENTRY,
  75         CN_FS_DEVRW,
  76         CN_MEM_SWAPOUT,
  77         CN_TIMERADD,
  78         CN_SCSI_DISPATCH_CMD,
  79         CN_IDE_CORE_CP,
  80         CN_DIRECT,
  81 };
  82
  83 enum ctype {
  84         CT_NONE,
  85         CT_PANIC,
  86         CT_BUG,
  87         CT_WARNING,
  88         CT_EXCEPTION,
  89         CT_LOOP,
  90         CT_OVERFLOW,
  91         CT_CORRUPT_STACK,
  92         CT_UNALIGNED_LOAD_STORE_WRITE,
  93         CT_OVERWRITE_ALLOCATION,
  94         CT_WRITE_AFTER_FREE,
  95         CT_READ_AFTER_FREE,
  96         CT_WRITE_BUDDY_AFTER_FREE,
  97         CT_READ_BUDDY_AFTER_FREE,
  98         CT_SOFTLOCKUP,
  99         CT_HARDLOCKUP,
 100         CT_SPINLOCKUP,
 101         CT_HUNG_TASK,
 102         CT_EXEC_DATA,
 103         CT_EXEC_STACK,
 104         CT_EXEC_KMALLOC,
 105         CT_EXEC_VMALLOC,
 106         CT_EXEC_USERSPACE,
 107         CT_ACCESS_USERSPACE,
 108         CT_WRITE_RO,
 109         CT_WRITE_RO_AFTER_INIT,
 110         CT_WRITE_KERN,
 111         CT_WRAP_ATOMIC
 112 };
 113
 114 static char* cp_name[] = {
 115         "INT_HARDWARE_ENTRY",
 116         "INT_HW_IRQ_EN",
 117         "INT_TASKLET_ENTRY",
 118         "FS_DEVRW",
 119         "MEM_SWAPOUT",
 120         "TIMERADD",
 121         "SCSI_DISPATCH_CMD",
 122         "IDE_CORE_CP",
 123         "DIRECT",
 124 };
 125
 126 static char* cp_type[] = {
 127         "PANIC",
 128         "BUG",
 129         "WARNING",
 130         "EXCEPTION",
 131         "LOOP",
 132         "OVERFLOW",
 133         "CORRUPT_STACK",
 134         "UNALIGNED_LOAD_STORE_WRITE",
 135         "OVERWRITE_ALLOCATION",
 136         "WRITE_AFTER_FREE",
 137         "READ_AFTER_FREE",
 138         "WRITE_BUDDY_AFTER_FREE",
 139         "READ_BUDDY_AFTER_FREE",
 140         "SOFTLOCKUP",
 141         "HARDLOCKUP",
 142         "SPINLOCKUP",
 143         "HUNG_TASK",
 144         "EXEC_DATA",
 145         "EXEC_STACK",
 146         "EXEC_KMALLOC",
 147         "EXEC_VMALLOC",
 148         "EXEC_USERSPACE",
 149         "ACCESS_USERSPACE",
 150         "WRITE_RO",
 151         "WRITE_RO_AFTER_INIT",
 152         "WRITE_KERN",
 153         "WRAP_ATOMIC"
 154 };
 155
 156 static struct jprobe lkdtm;
 157
 158 static int lkdtm_parse_commandline(void);
 159 static void lkdtm_handler(void);
 160
 161 static char* cpoint_name;
 162 static char* cpoint_type;
 163 static int cpoint_count = DEFAULT_COUNT;
 164 static int recur_count = REC_NUM_DEFAULT;
 165
 166 static enum cname cpoint = CN_INVALID;
 167 static enum ctype cptype = CT_NONE;
 168 static int count = DEFAULT_COUNT;
 169 static DEFINE_SPINLOCK(count_lock);
 170 static DEFINE_SPINLOCK(lock_me_up);
 171
 172 static u8 data_area[EXEC_SIZE];
 173
 174 static const unsigned long rodata = 0xAA55AA55;
 175 static unsigned long ro_after_init __ro_after_init = 0x55AA5500;
 176
 177 module_param(recur_count, int, 0644);
 178 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
 179 module_param(cpoint_name, charp, 0444);
 180 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
 181 module_param(cpoint_type, charp, 0444);
 182 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
 183                                 "hitting the crash point");
 184 module_param(cpoint_count, int, 0644);
 185 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
 186                                 "crash point is to be hit to trigger action");
 187
 188 static unsigned int jp_do_irq(unsigned int irq)
 189 {
 190         lkdtm_handler();
 191         jprobe_return();
 192         return 0;
 193 }
 194
 195 static irqreturn_t jp_handle_irq_event(unsigned int irq,
 196                                        struct irqaction *action)
 197 {
 198         lkdtm_handler();
 199         jprobe_return();
 200         return 0;
 201 }
 202
 203 static void jp_tasklet_action(struct softirq_action *a)
 204 {
 205         lkdtm_handler();
 206         jprobe_return();
 207 }
 208
 209 static void jp_ll_rw_block(int rw, int nr, struct buffer_head *bhs[])
 210 {
 211         lkdtm_handler();
 212         jprobe_return();
 213 }
 214
 215 struct scan_control;
 216
 217 static unsigned long jp_shrink_inactive_list(unsigned long max_scan,
 218                                              struct zone *zone,
 219                                              struct scan_control *sc)
 220 {
 221         lkdtm_handler();
 222         jprobe_return();
 223         return 0;
 224 }
 225
 226 static int jp_hrtimer_start(struct hrtimer *timer, ktime_t tim,
 227                             const enum hrtimer_mode mode)
 228 {
 229         lkdtm_handler();
 230         jprobe_return();
 231         return 0;
 232 }
 233
 234 static int jp_scsi_dispatch_cmd(struct scsi_cmnd *cmd)
 235 {
 236         lkdtm_handler();
 237         jprobe_return();
 238         return 0;
 239 }
 240
 241 #ifdef CONFIG_IDE
 242 static int jp_generic_ide_ioctl(ide_drive_t *drive, struct file *file,
 243                         struct block_device *bdev, unsigned int cmd,
 244                         unsigned long arg)
 245 {
 246         lkdtm_handler();
 247         jprobe_return();
 248         return 0;
 249 }
 250 #endif
 251
 252 /* Return the crashpoint number or NONE if the name is invalid */
 253 static enum ctype parse_cp_type(const char *what, size_t count)
 254 {
 255         int i;
 256
 257         for (i = 0; i < ARRAY_SIZE(cp_type); i++) {
 258                 if (!strcmp(what, cp_type[i]))
 259                         return i + 1;
 260         }
 261
 262         return CT_NONE;
 263 }
 264
 265 static const char *cp_type_to_str(enum ctype type)
 266 {
 267         if (type == CT_NONE || type < 0 || type > ARRAY_SIZE(cp_type))
 268                 return "None";
 269
 270         return cp_type[type - 1];
 271 }
 272
 273 static const char *cp_name_to_str(enum cname name)
 274 {
 275         if (name == CN_INVALID || name < 0 || name > ARRAY_SIZE(cp_name))
 276                 return "INVALID";
 277
 278         return cp_name[name - 1];
 279 }
 280
 281
 282 static int lkdtm_parse_commandline(void)
 283 {
 284         int i;
 285         unsigned long flags;
 286
 287         if (cpoint_count < 1 || recur_count < 1)
 288                 return -EINVAL;
 289
 290         spin_lock_irqsave(&count_lock, flags);
 291         count = cpoint_count;
 292         spin_unlock_irqrestore(&count_lock, flags);
 293
 294         /* No special parameters */
 295         if (!cpoint_type && !cpoint_name)
 296                 return 0;
 297
 298         /* Neither or both of these need to be set */
 299         if (!cpoint_type || !cpoint_name)
 300                 return -EINVAL;
 301
 302         cptype = parse_cp_type(cpoint_type, strlen(cpoint_type));
 303         if (cptype == CT_NONE)
 304                 return -EINVAL;
 305
 306         for (i = 0; i < ARRAY_SIZE(cp_name); i++) {
 307                 if (!strcmp(cpoint_name, cp_name[i])) {
 308                         cpoint = i + 1;
 309                         return 0;
 310                 }
 311         }
 312
 313         /* Could not find a valid crash point */
 314         return -EINVAL;
 315 }
 316
 317 static int recursive_loop(int remaining)
 318 {
 319         char buf[REC_STACK_SIZE];
 320
 321         /* Make sure compiler does not optimize this away. */
 322         memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE);
 323         if (!remaining)
 324                 return 0;
 325         else
 326                 return recursive_loop(remaining - 1);
 327 }
 328
 329 static void do_nothing(void)
 330 {
 331         return;
 332 }
 333
 334 /* Must immediately follow do_nothing for size calculuations to work out. */
 335 static void do_overwritten(void)
 336 {
 337         pr_info("do_overwritten wasn't overwritten!\n");
 338         return;
 339 }
 340
 341 static noinline void corrupt_stack(void)
 342 {
 343         /* Use default char array length that triggers stack protection. */
 344         char data[8];
 345
 346         memset((void *)data, 0, 64);
 347 }
 348
 349 static void noinline execute_location(void *dst)
 350 {
 351         void (*func)(void) = dst;
 352
 353         pr_info("attempting ok execution at %p\n", do_nothing);
 354         do_nothing();
 355
 356         memcpy(dst, do_nothing, EXEC_SIZE);
 357         flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
 358         pr_info("attempting bad execution at %p\n", func);
 359         func();
 360 }
 361
 362 static void execute_user_location(void *dst)
 363 {
 364         /* Intentionally crossing kernel/user memory boundary. */
 365         void (*func)(void) = dst;
 366
 367         pr_info("attempting ok execution at %p\n", do_nothing);
 368         do_nothing();
 369
 370         if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE))
 371                 return;
 372         flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE);
 373         pr_info("attempting bad execution at %p\n", func);
 374         func();
 375 }
 376
 377 static void lkdtm_do_action(enum ctype which)
 378 {
 379         switch (which) {
 380         case CT_PANIC:
 381                 panic("dumptest");
 382                 break;
 383         case CT_BUG:
 384                 BUG();
 385                 break;
 386         case CT_WARNING:
 387                 WARN_ON(1);
 388                 break;
 389         case CT_EXCEPTION:
 390                 *((int *) 0) = 0;
 391                 break;
 392         case CT_LOOP:
 393                 for (;;)
 394                         ;
 395                 break;
 396         case CT_OVERFLOW:
 397                 (void) recursive_loop(recur_count);
 398                 break;
 399         case CT_CORRUPT_STACK:
 400                 corrupt_stack();
 401                 break;
 402         case CT_UNALIGNED_LOAD_STORE_WRITE: {
 403                 static u8 data[5] __attribute__((aligned(4))) = {1, 2,
 404                                 3, 4, 5};
 405                 u32 *p;
 406                 u32 val = 0x12345678;
 407
 408                 p = (u32 *)(data + 1);
 409                 if (*p == 0)
 410                         val = 0x87654321;
 411                 *p = val;
 412                  break;
 413         }
 414         case CT_OVERWRITE_ALLOCATION: {
 415                 size_t len = 1020;
 416                 u32 *data = kmalloc(len, GFP_KERNEL);
 417
 418                 data[1024 / sizeof(u32)] = 0x12345678;
 419                 kfree(data);
 420                 break;
 421         }
 422         case CT_WRITE_AFTER_FREE: {
 423                 int *base, *again;
 424                 size_t len = 1024;
 425                 /*
 426                  * The slub allocator uses the first word to store the free
 427                  * pointer in some configurations. Use the middle of the
 428                  * allocation to avoid running into the freelist
 429                  */
 430                 size_t offset = (len / sizeof(*base)) / 2;
 431
 432                 base = kmalloc(len, GFP_KERNEL);
 433                 pr_info("Allocated memory %p-%p\n", base, &base[offset * 2]);
 434                 pr_info("Attempting bad write to freed memory at %p\n",
 435                         &base[offset]);
 436                 kfree(base);
 437                 base[offset] = 0x0abcdef0;
 438                 /* Attempt to notice the overwrite. */
 439                 again = kmalloc(len, GFP_KERNEL);
 440                 kfree(again);
 441                 if (again != base)
 442                         pr_info("Hmm, didn't get the same memory range.\n");
 443
 444                 break;
 445         }
 446         case CT_READ_AFTER_FREE: {
 447                 int *base, *val, saw;
 448                 size_t len = 1024;
 449                 /*
 450                  * The slub allocator uses the first word to store the free
 451                  * pointer in some configurations. Use the middle of the
 452                  * allocation to avoid running into the freelist
 453                  */
 454                 size_t offset = (len / sizeof(*base)) / 2;
 455
 456                 base = kmalloc(len, GFP_KERNEL);
 457                 if (!base)
 458                         break;
 459
 460                 val = kmalloc(len, GFP_KERNEL);
 461                 if (!val)
 462                         break;
 463
 464                 *val = 0x12345678;
 465                 base[offset] = *val;
 466                 pr_info("Value in memory before free: %x\n", base[offset]);
 467
 468                 kfree(base);
 469
 470                 pr_info("Attempting bad read from freed memory\n");
 471                 saw = base[offset];
 472                 if (saw != *val) {
 473                         /* Good! Poisoning happened, so declare a win. */
 474                         pr_info("Memory correctly poisoned (%x)\n", saw);
 475                         BUG();
 476                 }
 477                 pr_info("Memory was not poisoned\n");
 478
 479                 kfree(val);
 480                 break;
 481         }
 482         case CT_WRITE_BUDDY_AFTER_FREE: {
 483                 unsigned long p = __get_free_page(GFP_KERNEL);
 484                 if (!p)
 485                         break;
 486                 pr_info("Writing to the buddy page before free\n");
 487                 memset((void *)p, 0x3, PAGE_SIZE);
 488                 free_page(p);
 489                 schedule();
 490                 pr_info("Attempting bad write to the buddy page after free\n");
 491                 memset((void *)p, 0x78, PAGE_SIZE);
 492                 /* Attempt to notice the overwrite. */
 493                 p = __get_free_page(GFP_KERNEL);
 494                 free_page(p);
 495                 schedule();
 496
 497                 break;
 498         }
 499         case CT_READ_BUDDY_AFTER_FREE: {
 500                 unsigned long p = __get_free_page(GFP_KERNEL);
 501                 int saw, *val = kmalloc(1024, GFP_KERNEL);
 502                 int *base;
 503
 504                 if (!p)
 505                         break;
 506
 507                 if (!val)
 508                         break;
 509
 510                 base = (int *)p;
 511
 512                 *val = 0x12345678;
 513                 base[0] = *val;
 514                 pr_info("Value in memory before free: %x\n", base[0]);
 515                 free_page(p);
 516                 pr_info("Attempting to read from freed memory\n");
 517                 saw = base[0];
 518                 if (saw != *val) {
 519                         /* Good! Poisoning happened, so declare a win. */
 520                         pr_info("Memory correctly poisoned (%x)\n", saw);
 521                         BUG();
 522                 }
 523                 pr_info("Buddy page was not poisoned\n");
 524
 525                 kfree(val);
 526                 break;
 527         }
 528         case CT_SOFTLOCKUP:
 529                 preempt_disable();
 530                 for (;;)
 531                         cpu_relax();
 532                 break;
 533         case CT_HARDLOCKUP:
 534                 local_irq_disable();
 535                 for (;;)
 536                         cpu_relax();
 537                 break;
 538         case CT_SPINLOCKUP:
 539                 /* Must be called twice to trigger. */
 540                 spin_lock(&lock_me_up);
 541                 /* Let sparse know we intended to exit holding the lock. */
 542                 __release(&lock_me_up);
 543                 break;
 544         case CT_HUNG_TASK:
 545                 set_current_state(TASK_UNINTERRUPTIBLE);
 546                 schedule();
 547                 break;
 548         case CT_EXEC_DATA:
 549                 execute_location(data_area);
 550                 break;
 551         case CT_EXEC_STACK: {
 552                 u8 stack_area[EXEC_SIZE];
 553                 execute_location(stack_area);
 554                 break;
 555         }
 556         case CT_EXEC_KMALLOC: {
 557                 u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL);
 558                 execute_location(kmalloc_area);
 559                 kfree(kmalloc_area);
 560                 break;
 561         }
 562         case CT_EXEC_VMALLOC: {
 563                 u32 *vmalloc_area = vmalloc(EXEC_SIZE);
 564                 execute_location(vmalloc_area);
 565                 vfree(vmalloc_area);
 566                 break;
 567         }
 568         case CT_EXEC_USERSPACE: {
 569                 unsigned long user_addr;
 570
 571                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 572                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 573                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 574                 if (user_addr >= TASK_SIZE) {
 575                         pr_warn("Failed to allocate user memory\n");
 576                         return;
 577                 }
 578                 execute_user_location((void *)user_addr);
 579                 vm_munmap(user_addr, PAGE_SIZE);
 580                 break;
 581         }
 582         case CT_ACCESS_USERSPACE: {
 583                 unsigned long user_addr, tmp = 0;
 584                 unsigned long *ptr;
 585
 586                 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
 587                                     PROT_READ | PROT_WRITE | PROT_EXEC,
 588                                     MAP_ANONYMOUS | MAP_PRIVATE, 0);
 589                 if (user_addr >= TASK_SIZE) {
 590                         pr_warn("Failed to allocate user memory\n");
 591                         return;
 592                 }
 593
 594                 if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) {
 595                         pr_warn("copy_to_user failed\n");
 596                         vm_munmap(user_addr, PAGE_SIZE);
 597                         return;
 598                 }
 599
 600                 ptr = (unsigned long *)user_addr;
 601
 602                 pr_info("attempting bad read at %p\n", ptr);
 603                 tmp = *ptr;
 604                 tmp += 0xc0dec0de;
 605
 606                 pr_info("attempting bad write at %p\n", ptr);
 607                 *ptr = tmp;
 608
 609                 vm_munmap(user_addr, PAGE_SIZE);
 610
 611                 break;
 612         }
 613         case CT_WRITE_RO: {
 614                 /* Explicitly cast away "const" for the test. */
 615                 unsigned long *ptr = (unsigned long *)&rodata;
 616
 617                 pr_info("attempting bad rodata write at %p\n", ptr);
 618                 *ptr ^= 0xabcd1234;
 619
 620                 break;
 621         }
 622         case CT_WRITE_RO_AFTER_INIT: {
 623                 unsigned long *ptr = &ro_after_init;
 624
 625                 /*
 626                  * Verify we were written to during init. Since an Oops
 627                  * is considered a "success", a failure is to just skip the
 628                  * real test.
 629                  */
 630                 if ((*ptr & 0xAA) != 0xAA) {
 631                         pr_info("%p was NOT written during init!?\n", ptr);
 632                         break;
 633                 }
 634
 635                 pr_info("attempting bad ro_after_init write at %p\n", ptr);
 636                 *ptr ^= 0xabcd1234;
 637
 638                 break;
 639         }
 640         case CT_WRITE_KERN: {
 641                 size_t size;
 642                 unsigned char *ptr;
 643
 644                 size = (unsigned long)do_overwritten -
 645                        (unsigned long)do_nothing;
 646                 ptr = (unsigned char *)do_overwritten;
 647
 648                 pr_info("attempting bad %zu byte write at %p\n", size, ptr);
 649                 memcpy(ptr, (unsigned char *)do_nothing, size);
 650                 flush_icache_range((unsigned long)ptr,
 651                                    (unsigned long)(ptr + size));
 652
 653                 do_overwritten();
 654                 break;
 655         }
 656         case CT_WRAP_ATOMIC: {
 657                 atomic_t under = ATOMIC_INIT(INT_MIN);
 658                 atomic_t over = ATOMIC_INIT(INT_MAX);
 659
 660                 pr_info("attempting atomic underflow\n");
 661                 atomic_dec(&under);
 662                 pr_info("attempting atomic overflow\n");
 663                 atomic_inc(&over);
 664
 665                 return;
 666         }
 667         case CT_NONE:
 668         default:
 669                 break;
 670         }
 671
 672 }
 673
 674 static void lkdtm_handler(void)
 675 {
 676         unsigned long flags;
 677         bool do_it = false;
 678
 679         spin_lock_irqsave(&count_lock, flags);
 680         count--;
 681         pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
 682                 cp_name_to_str(cpoint), cp_type_to_str(cptype), count);
 683
 684         if (count == 0) {
 685                 do_it = true;
 686                 count = cpoint_count;
 687         }
 688         spin_unlock_irqrestore(&count_lock, flags);
 689
 690         if (do_it)
 691                 lkdtm_do_action(cptype);
 692 }
 693
 694 static int lkdtm_register_cpoint(enum cname which)
 695 {
 696         int ret;
 697
 698         cpoint = CN_INVALID;
 699         if (lkdtm.entry != NULL)
 700                 unregister_jprobe(&lkdtm);
 701
 702         switch (which) {
 703         case CN_DIRECT:
 704                 lkdtm_do_action(cptype);
 705                 return 0;
 706         case CN_INT_HARDWARE_ENTRY:
 707                 lkdtm.kp.symbol_name = "do_IRQ";
 708                 lkdtm.entry = (kprobe_opcode_t*) jp_do_irq;
 709                 break;
 710         case CN_INT_HW_IRQ_EN:
 711                 lkdtm.kp.symbol_name = "handle_IRQ_event";
 712                 lkdtm.entry = (kprobe_opcode_t*) jp_handle_irq_event;
 713                 break;
 714         case CN_INT_TASKLET_ENTRY:
 715                 lkdtm.kp.symbol_name = "tasklet_action";
 716                 lkdtm.entry = (kprobe_opcode_t*) jp_tasklet_action;
 717                 break;
 718         case CN_FS_DEVRW:
 719                 lkdtm.kp.symbol_name = "ll_rw_block";
 720                 lkdtm.entry = (kprobe_opcode_t*) jp_ll_rw_block;
 721                 break;
 722         case CN_MEM_SWAPOUT:
 723                 lkdtm.kp.symbol_name = "shrink_inactive_list";
 724                 lkdtm.entry = (kprobe_opcode_t*) jp_shrink_inactive_list;
 725                 break;
 726         case CN_TIMERADD:
 727                 lkdtm.kp.symbol_name = "hrtimer_start";
 728                 lkdtm.entry = (kprobe_opcode_t*) jp_hrtimer_start;
 729                 break;
 730         case CN_SCSI_DISPATCH_CMD:
 731                 lkdtm.kp.symbol_name = "scsi_dispatch_cmd";
 732                 lkdtm.entry = (kprobe_opcode_t*) jp_scsi_dispatch_cmd;
 733                 break;
 734         case CN_IDE_CORE_CP:
 735 #ifdef CONFIG_IDE
 736                 lkdtm.kp.symbol_name = "generic_ide_ioctl";
 737                 lkdtm.entry = (kprobe_opcode_t*) jp_generic_ide_ioctl;
 738 #else
 739                 pr_info("Crash point not available\n");
 740                 return -EINVAL;
 741 #endif
 742                 break;
 743         default:
 744                 pr_info("Invalid Crash Point\n");
 745                 return -EINVAL;
 746         }
 747
 748         cpoint = which;
 749         if ((ret = register_jprobe(&lkdtm)) < 0) {
 750                 pr_info("Couldn't register jprobe\n");
 751                 cpoint = CN_INVALID;
 752         }
 753
 754         return ret;
 755 }
 756
 757 static ssize_t do_register_entry(enum cname which, struct file *f,
 758                 const char __user *user_buf, size_t count, loff_t *off)
 759 {
 760         char *buf;
 761         int err;
 762
 763         if (count >= PAGE_SIZE)
 764                 return -EINVAL;
 765
 766         buf = (char *)__get_free_page(GFP_KERNEL);
 767         if (!buf)
 768                 return -ENOMEM;
 769         if (copy_from_user(buf, user_buf, count)) {
 770                 free_page((unsigned long) buf);
 771                 return -EFAULT;
 772         }
 773         /* NULL-terminate and remove enter */
 774         buf[count] = '\0';
 775         strim(buf);
 776
 777         cptype = parse_cp_type(buf, count);
 778         free_page((unsigned long) buf);
 779
 780         if (cptype == CT_NONE)
 781                 return -EINVAL;
 782
 783         err = lkdtm_register_cpoint(which);
 784         if (err < 0)
 785                 return err;
 786
 787         *off += count;
 788
 789         return count;
 790 }
 791
 792 /* Generic read callback that just prints out the available crash types */
 793 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
 794                 size_t count, loff_t *off)
 795 {
 796         char *buf;
 797         int i, n, out;
 798
 799         buf = (char *)__get_free_page(GFP_KERNEL);
 800         if (buf == NULL)
 801                 return -ENOMEM;
 802
 803         n = snprintf(buf, PAGE_SIZE, "Available crash types:\n");
 804         for (i = 0; i < ARRAY_SIZE(cp_type); i++)
 805                 n += snprintf(buf + n, PAGE_SIZE - n, "%s\n", cp_type[i]);
 806         buf[n] = '\0';
 807
 808         out = simple_read_from_buffer(user_buf, count, off,
 809                                       buf, n);
 810         free_page((unsigned long) buf);
 811
 812         return out;
 813 }
 814
 815 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
 816 {
 817         return 0;
 818 }
 819
 820
 821 static ssize_t int_hardware_entry(struct file *f, const char __user *buf,
 822                 size_t count, loff_t *off)
 823 {
 824         return do_register_entry(CN_INT_HARDWARE_ENTRY, f, buf, count, off);
 825 }
 826
 827 static ssize_t int_hw_irq_en(struct file *f, const char __user *buf,
 828                 size_t count, loff_t *off)
 829 {
 830         return do_register_entry(CN_INT_HW_IRQ_EN, f, buf, count, off);
 831 }
 832
 833 static ssize_t int_tasklet_entry(struct file *f, const char __user *buf,
 834                 size_t count, loff_t *off)
 835 {
 836         return do_register_entry(CN_INT_TASKLET_ENTRY, f, buf, count, off);
 837 }
 838
 839 static ssize_t fs_devrw_entry(struct file *f, const char __user *buf,
 840                 size_t count, loff_t *off)
 841 {
 842         return do_register_entry(CN_FS_DEVRW, f, buf, count, off);
 843 }
 844
 845 static ssize_t mem_swapout_entry(struct file *f, const char __user *buf,
 846                 size_t count, loff_t *off)
 847 {
 848         return do_register_entry(CN_MEM_SWAPOUT, f, buf, count, off);
 849 }
 850
 851 static ssize_t timeradd_entry(struct file *f, const char __user *buf,
 852                 size_t count, loff_t *off)
 853 {
 854         return do_register_entry(CN_TIMERADD, f, buf, count, off);
 855 }
 856
 857 static ssize_t scsi_dispatch_cmd_entry(struct file *f,
 858                 const char __user *buf, size_t count, loff_t *off)
 859 {
 860         return do_register_entry(CN_SCSI_DISPATCH_CMD, f, buf, count, off);
 861 }
 862
 863 static ssize_t ide_core_cp_entry(struct file *f, const char __user *buf,
 864                 size_t count, loff_t *off)
 865 {
 866         return do_register_entry(CN_IDE_CORE_CP, f, buf, count, off);
 867 }
 868
 869 /* Special entry to just crash directly. Available without KPROBEs */
 870 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
 871                 size_t count, loff_t *off)
 872 {
 873         enum ctype type;
 874         char *buf;
 875
 876         if (count >= PAGE_SIZE)
 877                 return -EINVAL;
 878         if (count < 1)
 879                 return -EINVAL;
 880
 881         buf = (char *)__get_free_page(GFP_KERNEL);
 882         if (!buf)
 883                 return -ENOMEM;
 884         if (copy_from_user(buf, user_buf, count)) {
 885                 free_page((unsigned long) buf);
 886                 return -EFAULT;
 887         }
 888         /* NULL-terminate and remove enter */
 889         buf[count] = '\0';
 890         strim(buf);
 891
 892         type = parse_cp_type(buf, count);
 893         free_page((unsigned long) buf);
 894         if (type == CT_NONE)
 895                 return -EINVAL;
 896
 897         pr_info("Performing direct entry %s\n", cp_type_to_str(type));
 898         lkdtm_do_action(type);
 899         *off += count;
 900
 901         return count;
 902 }
 903
 904 struct crash_entry {
 905         const char *name;
 906         const struct file_operations fops;
 907 };
 908
 909 static const struct crash_entry crash_entries[] = {
 910         {"DIRECT", {.read = lkdtm_debugfs_read,
 911                         .llseek = generic_file_llseek,
 912                         .open = lkdtm_debugfs_open,
 913                         .write = direct_entry} },
 914         {"INT_HARDWARE_ENTRY", {.read = lkdtm_debugfs_read,
 915                         .llseek = generic_file_llseek,
 916                         .open = lkdtm_debugfs_open,
 917                         .write = int_hardware_entry} },
 918         {"INT_HW_IRQ_EN", {.read = lkdtm_debugfs_read,
 919                         .llseek = generic_file_llseek,
 920                         .open = lkdtm_debugfs_open,
 921                         .write = int_hw_irq_en} },
 922         {"INT_TASKLET_ENTRY", {.read = lkdtm_debugfs_read,
 923                         .llseek = generic_file_llseek,
 924                         .open = lkdtm_debugfs_open,
 925                         .write = int_tasklet_entry} },
 926         {"FS_DEVRW", {.read = lkdtm_debugfs_read,
 927                         .llseek = generic_file_llseek,
 928                         .open = lkdtm_debugfs_open,
 929                         .write = fs_devrw_entry} },
 930         {"MEM_SWAPOUT", {.read = lkdtm_debugfs_read,
 931                         .llseek = generic_file_llseek,
 932                         .open = lkdtm_debugfs_open,
 933                         .write = mem_swapout_entry} },
 934         {"TIMERADD", {.read = lkdtm_debugfs_read,
 935                         .llseek = generic_file_llseek,
 936                         .open = lkdtm_debugfs_open,
 937                         .write = timeradd_entry} },
 938         {"SCSI_DISPATCH_CMD", {.read = lkdtm_debugfs_read,
 939                         .llseek = generic_file_llseek,
 940                         .open = lkdtm_debugfs_open,
 941                         .write = scsi_dispatch_cmd_entry} },
 942         {"IDE_CORE_CP", {.read = lkdtm_debugfs_read,
 943                         .llseek = generic_file_llseek,
 944                         .open = lkdtm_debugfs_open,
 945                         .write = ide_core_cp_entry} },
 946 };
 947
 948 static struct dentry *lkdtm_debugfs_root;
 949
 950 static int __init lkdtm_module_init(void)
 951 {
 952         int ret = -EINVAL;
 953         int n_debugfs_entries = 1; /* Assume only the direct entry */
 954         int i;
 955
 956         /* Make sure we can write to __ro_after_init values during __init */
 957         ro_after_init |= 0xAA;
 958
 959         /* Register debugfs interface */
 960         lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
 961         if (!lkdtm_debugfs_root) {
 962                 pr_err("creating root dir failed\n");
 963                 return -ENODEV;
 964         }
 965
 966 #ifdef CONFIG_KPROBES
 967         n_debugfs_entries = ARRAY_SIZE(crash_entries);
 968 #endif
 969
 970         for (i = 0; i < n_debugfs_entries; i++) {
 971                 const struct crash_entry *cur = &crash_entries[i];
 972                 struct dentry *de;
 973
 974                 de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
 975                                 NULL, &cur->fops);
 976                 if (de == NULL) {
 977                         pr_err("could not create %s\n", cur->name);
 978                         goto out_err;
 979                 }
 980         }
 981
 982         if (lkdtm_parse_commandline() == -EINVAL) {
 983                 pr_info("Invalid command\n");
 984                 goto out_err;
 985         }
 986
 987         if (cpoint != CN_INVALID && cptype != CT_NONE) {
 988                 ret = lkdtm_register_cpoint(cpoint);
 989                 if (ret < 0) {
 990                         pr_info("Invalid crash point %d\n", cpoint);
 991                         goto out_err;
 992                 }
 993                 pr_info("Crash point %s of type %s registered\n",
 994                         cpoint_name, cpoint_type);
 995         } else {
 996                 pr_info("No crash points registered, enable through debugfs\n");
 997         }
 998
 999         return 0;
1000
1001 out_err:
1002         debugfs_remove_recursive(lkdtm_debugfs_root);
1003         return ret;
1004 }
1005
1006 static void __exit lkdtm_module_exit(void)
1007 {
1008         debugfs_remove_recursive(lkdtm_debugfs_root);
1009
1010         unregister_jprobe(&lkdtm);
1011         pr_info("Crash point unregistered\n");
1012 }
1013
1014 module_init(lkdtm_module_init);
1015 module_exit(lkdtm_module_exit);
1016
1017 MODULE_LICENSE("GPL");
1018 MODULE_DESCRIPTION("Kprobe module for testing crash dumps");