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 */
find_crashtype(const char * name)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 */
lkdtm_do_action(const struct crashtype * crashtype)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
lkdtm_register_cpoint(struct crashpoint * crashpoint,const struct crashtype * crashtype)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. */
lkdtm_kprobe_handler(struct kprobe * kp,struct pt_regs * regs)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
lkdtm_debugfs_entry(struct file * f,const char __user * user_buf,size_t count,loff_t * off)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 */
lkdtm_debugfs_read(struct file * f,char __user * user_buf,size_t count,loff_t * off)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
lkdtm_debugfs_open(struct inode * inode,struct file * file)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 */
direct_entry(struct file * f,const char __user * user_buf,size_t count,loff_t * off)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
lkdtm_module_init(void)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
lkdtm_module_exit(void)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");
492