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_QUEUE_RQ", "scsi_queue_rq"),
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 CRASHTYPE(DOUBLE_FAULT),
177 };
178
179
180 /* Global kprobe entry and crashtype. */
181 static struct kprobe *lkdtm_kprobe;
182 static struct crashpoint *lkdtm_crashpoint;
183 static const struct crashtype *lkdtm_crashtype;
184
185 /* Module parameters */
186 static int recur_count = -1;
187 module_param(recur_count, int, 0644);
188 MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
189
190 static char* cpoint_name;
191 module_param(cpoint_name, charp, 0444);
192 MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
193
194 static char* cpoint_type;
195 module_param(cpoint_type, charp, 0444);
196 MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
197 "hitting the crash point");
198
199 static int cpoint_count = DEFAULT_COUNT;
200 module_param(cpoint_count, int, 0644);
201 MODULE_PARM_DESC(cpoint_count, " Crash Point Count, number of times the "\
202 "crash point is to be hit to trigger action");
203
204
205 /* Return the crashtype number or NULL if the name is invalid */
find_crashtype(const char * name)206 static const struct crashtype *find_crashtype(const char *name)
207 {
208 int i;
209
210 for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
211 if (!strcmp(name, crashtypes[i].name))
212 return &crashtypes[i];
213 }
214
215 return NULL;
216 }
217
218 /*
219 * This is forced noinline just so it distinctly shows up in the stackdump
220 * which makes validation of expected lkdtm crashes easier.
221 */
lkdtm_do_action(const struct crashtype * crashtype)222 static noinline void lkdtm_do_action(const struct crashtype *crashtype)
223 {
224 if (WARN_ON(!crashtype || !crashtype->func))
225 return;
226 crashtype->func();
227 }
228
lkdtm_register_cpoint(struct crashpoint * crashpoint,const struct crashtype * crashtype)229 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
230 const struct crashtype *crashtype)
231 {
232 int ret;
233
234 /* If this doesn't have a symbol, just call immediately. */
235 if (!crashpoint->kprobe.symbol_name) {
236 lkdtm_do_action(crashtype);
237 return 0;
238 }
239
240 if (lkdtm_kprobe != NULL)
241 unregister_kprobe(lkdtm_kprobe);
242
243 lkdtm_crashpoint = crashpoint;
244 lkdtm_crashtype = crashtype;
245 lkdtm_kprobe = &crashpoint->kprobe;
246 ret = register_kprobe(lkdtm_kprobe);
247 if (ret < 0) {
248 pr_info("Couldn't register kprobe %s\n",
249 crashpoint->kprobe.symbol_name);
250 lkdtm_kprobe = NULL;
251 lkdtm_crashpoint = NULL;
252 lkdtm_crashtype = NULL;
253 }
254
255 return ret;
256 }
257
258 #ifdef CONFIG_KPROBES
259 /* Global crash counter and spinlock. */
260 static int crash_count = DEFAULT_COUNT;
261 static DEFINE_SPINLOCK(crash_count_lock);
262
263 /* Called by kprobe entry points. */
lkdtm_kprobe_handler(struct kprobe * kp,struct pt_regs * regs)264 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
265 {
266 unsigned long flags;
267 bool do_it = false;
268
269 if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
270 return 0;
271
272 spin_lock_irqsave(&crash_count_lock, flags);
273 crash_count--;
274 pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
275 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
276
277 if (crash_count == 0) {
278 do_it = true;
279 crash_count = cpoint_count;
280 }
281 spin_unlock_irqrestore(&crash_count_lock, flags);
282
283 if (do_it)
284 lkdtm_do_action(lkdtm_crashtype);
285
286 return 0;
287 }
288
lkdtm_debugfs_entry(struct file * f,const char __user * user_buf,size_t count,loff_t * off)289 static ssize_t lkdtm_debugfs_entry(struct file *f,
290 const char __user *user_buf,
291 size_t count, loff_t *off)
292 {
293 struct crashpoint *crashpoint = file_inode(f)->i_private;
294 const struct crashtype *crashtype = NULL;
295 char *buf;
296 int err;
297
298 if (count >= PAGE_SIZE)
299 return -EINVAL;
300
301 buf = (char *)__get_free_page(GFP_KERNEL);
302 if (!buf)
303 return -ENOMEM;
304 if (copy_from_user(buf, user_buf, count)) {
305 free_page((unsigned long) buf);
306 return -EFAULT;
307 }
308 /* NULL-terminate and remove enter */
309 buf[count] = '\0';
310 strim(buf);
311
312 crashtype = find_crashtype(buf);
313 free_page((unsigned long)buf);
314
315 if (!crashtype)
316 return -EINVAL;
317
318 err = lkdtm_register_cpoint(crashpoint, crashtype);
319 if (err < 0)
320 return err;
321
322 *off += count;
323
324 return count;
325 }
326 #endif
327
328 /* 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)329 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
330 size_t count, loff_t *off)
331 {
332 char *buf;
333 int i, n, out;
334
335 buf = (char *)__get_free_page(GFP_KERNEL);
336 if (buf == NULL)
337 return -ENOMEM;
338
339 n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
340 for (i = 0; i < ARRAY_SIZE(crashtypes); i++) {
341 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
342 crashtypes[i].name);
343 }
344 buf[n] = '\0';
345
346 out = simple_read_from_buffer(user_buf, count, off,
347 buf, n);
348 free_page((unsigned long) buf);
349
350 return out;
351 }
352
lkdtm_debugfs_open(struct inode * inode,struct file * file)353 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
354 {
355 return 0;
356 }
357
358 /* 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)359 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
360 size_t count, loff_t *off)
361 {
362 const struct crashtype *crashtype;
363 char *buf;
364
365 if (count >= PAGE_SIZE)
366 return -EINVAL;
367 if (count < 1)
368 return -EINVAL;
369
370 buf = (char *)__get_free_page(GFP_KERNEL);
371 if (!buf)
372 return -ENOMEM;
373 if (copy_from_user(buf, user_buf, count)) {
374 free_page((unsigned long) buf);
375 return -EFAULT;
376 }
377 /* NULL-terminate and remove enter */
378 buf[count] = '\0';
379 strim(buf);
380
381 crashtype = find_crashtype(buf);
382 free_page((unsigned long) buf);
383 if (!crashtype)
384 return -EINVAL;
385
386 pr_info("Performing direct entry %s\n", crashtype->name);
387 lkdtm_do_action(crashtype);
388 *off += count;
389
390 return count;
391 }
392
393 static struct dentry *lkdtm_debugfs_root;
394
lkdtm_module_init(void)395 static int __init lkdtm_module_init(void)
396 {
397 struct crashpoint *crashpoint = NULL;
398 const struct crashtype *crashtype = NULL;
399 int ret;
400 int i;
401
402 /* Neither or both of these need to be set */
403 if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
404 pr_err("Need both cpoint_type and cpoint_name or neither\n");
405 return -EINVAL;
406 }
407
408 if (cpoint_type) {
409 crashtype = find_crashtype(cpoint_type);
410 if (!crashtype) {
411 pr_err("Unknown crashtype '%s'\n", cpoint_type);
412 return -EINVAL;
413 }
414 }
415
416 if (cpoint_name) {
417 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
418 if (!strcmp(cpoint_name, crashpoints[i].name))
419 crashpoint = &crashpoints[i];
420 }
421
422 /* Refuse unknown crashpoints. */
423 if (!crashpoint) {
424 pr_err("Invalid crashpoint %s\n", cpoint_name);
425 return -EINVAL;
426 }
427 }
428
429 #ifdef CONFIG_KPROBES
430 /* Set crash count. */
431 crash_count = cpoint_count;
432 #endif
433
434 /* Handle test-specific initialization. */
435 lkdtm_bugs_init(&recur_count);
436 lkdtm_perms_init();
437 lkdtm_usercopy_init();
438 lkdtm_heap_init();
439
440 /* Register debugfs interface */
441 lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
442
443 /* Install debugfs trigger files. */
444 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
445 struct crashpoint *cur = &crashpoints[i];
446
447 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
448 &cur->fops);
449 }
450
451 /* Install crashpoint if one was selected. */
452 if (crashpoint) {
453 ret = lkdtm_register_cpoint(crashpoint, crashtype);
454 if (ret < 0) {
455 pr_info("Invalid crashpoint %s\n", crashpoint->name);
456 goto out_err;
457 }
458 pr_info("Crash point %s of type %s registered\n",
459 crashpoint->name, cpoint_type);
460 } else {
461 pr_info("No crash points registered, enable through debugfs\n");
462 }
463
464 return 0;
465
466 out_err:
467 debugfs_remove_recursive(lkdtm_debugfs_root);
468 return ret;
469 }
470
lkdtm_module_exit(void)471 static void __exit lkdtm_module_exit(void)
472 {
473 debugfs_remove_recursive(lkdtm_debugfs_root);
474
475 /* Handle test-specific clean-up. */
476 lkdtm_heap_exit();
477 lkdtm_usercopy_exit();
478
479 if (lkdtm_kprobe != NULL)
480 unregister_kprobe(lkdtm_kprobe);
481
482 pr_info("Crash point unregistered\n");
483 }
484
485 module_init(lkdtm_module_init);
486 module_exit(lkdtm_module_exit);
487
488 MODULE_LICENSE("GPL");
489 MODULE_DESCRIPTION("Kernel crash testing module");
490