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_DEVRW", "ll_rw_block"),
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 */
find_crashtype(const char * name)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 */
lkdtm_do_action(const struct crashtype * crashtype)157 static noinline void lkdtm_do_action(const struct crashtype *crashtype)
158 {
159 if (WARN_ON(!crashtype || !crashtype->func))
160 return;
161 crashtype->func();
162 }
163
lkdtm_register_cpoint(struct crashpoint * crashpoint,const struct crashtype * crashtype)164 static int lkdtm_register_cpoint(struct crashpoint *crashpoint,
165 const struct crashtype *crashtype)
166 {
167 int ret;
168
169 /* If this doesn't have a symbol, just call immediately. */
170 if (!crashpoint->kprobe.symbol_name) {
171 lkdtm_do_action(crashtype);
172 return 0;
173 }
174
175 if (lkdtm_kprobe != NULL)
176 unregister_kprobe(lkdtm_kprobe);
177
178 lkdtm_crashpoint = crashpoint;
179 lkdtm_crashtype = crashtype;
180 lkdtm_kprobe = &crashpoint->kprobe;
181 ret = register_kprobe(lkdtm_kprobe);
182 if (ret < 0) {
183 pr_info("Couldn't register kprobe %s\n",
184 crashpoint->kprobe.symbol_name);
185 lkdtm_kprobe = NULL;
186 lkdtm_crashpoint = NULL;
187 lkdtm_crashtype = NULL;
188 }
189
190 return ret;
191 }
192
193 #ifdef CONFIG_KPROBES
194 /* Global crash counter and spinlock. */
195 static int crash_count = DEFAULT_COUNT;
196 static DEFINE_SPINLOCK(crash_count_lock);
197
198 /* Called by kprobe entry points. */
lkdtm_kprobe_handler(struct kprobe * kp,struct pt_regs * regs)199 static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs)
200 {
201 unsigned long flags;
202 bool do_it = false;
203
204 if (WARN_ON(!lkdtm_crashpoint || !lkdtm_crashtype))
205 return 0;
206
207 spin_lock_irqsave(&crash_count_lock, flags);
208 crash_count--;
209 pr_info("Crash point %s of type %s hit, trigger in %d rounds\n",
210 lkdtm_crashpoint->name, lkdtm_crashtype->name, crash_count);
211
212 if (crash_count == 0) {
213 do_it = true;
214 crash_count = cpoint_count;
215 }
216 spin_unlock_irqrestore(&crash_count_lock, flags);
217
218 if (do_it)
219 lkdtm_do_action(lkdtm_crashtype);
220
221 return 0;
222 }
223
lkdtm_debugfs_entry(struct file * f,const char __user * user_buf,size_t count,loff_t * off)224 static ssize_t lkdtm_debugfs_entry(struct file *f,
225 const char __user *user_buf,
226 size_t count, loff_t *off)
227 {
228 struct crashpoint *crashpoint = file_inode(f)->i_private;
229 const struct crashtype *crashtype = NULL;
230 char *buf;
231 int err;
232
233 if (count >= PAGE_SIZE)
234 return -EINVAL;
235
236 buf = (char *)__get_free_page(GFP_KERNEL);
237 if (!buf)
238 return -ENOMEM;
239 if (copy_from_user(buf, user_buf, count)) {
240 free_page((unsigned long) buf);
241 return -EFAULT;
242 }
243 /* NULL-terminate and remove enter */
244 buf[count] = '\0';
245 strim(buf);
246
247 crashtype = find_crashtype(buf);
248 free_page((unsigned long)buf);
249
250 if (!crashtype)
251 return -EINVAL;
252
253 err = lkdtm_register_cpoint(crashpoint, crashtype);
254 if (err < 0)
255 return err;
256
257 *off += count;
258
259 return count;
260 }
261 #endif
262
263 /* 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)264 static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
265 size_t count, loff_t *off)
266 {
267 int n, cat, idx;
268 ssize_t out;
269 char *buf;
270
271 buf = (char *)__get_free_page(GFP_KERNEL);
272 if (buf == NULL)
273 return -ENOMEM;
274
275 n = scnprintf(buf, PAGE_SIZE, "Available crash types:\n");
276
277 for (cat = 0; cat < ARRAY_SIZE(crashtype_categories); cat++) {
278 for (idx = 0; idx < crashtype_categories[cat]->len; idx++) {
279 struct crashtype *crashtype;
280
281 crashtype = &crashtype_categories[cat]->crashtypes[idx];
282 n += scnprintf(buf + n, PAGE_SIZE - n, "%s\n",
283 crashtype->name);
284 }
285 }
286 buf[n] = '\0';
287
288 out = simple_read_from_buffer(user_buf, count, off,
289 buf, n);
290 free_page((unsigned long) buf);
291
292 return out;
293 }
294
lkdtm_debugfs_open(struct inode * inode,struct file * file)295 static int lkdtm_debugfs_open(struct inode *inode, struct file *file)
296 {
297 return 0;
298 }
299
300 /* 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)301 static ssize_t direct_entry(struct file *f, const char __user *user_buf,
302 size_t count, loff_t *off)
303 {
304 const struct crashtype *crashtype;
305 char *buf;
306
307 if (count >= PAGE_SIZE)
308 return -EINVAL;
309 if (count < 1)
310 return -EINVAL;
311
312 buf = (char *)__get_free_page(GFP_KERNEL);
313 if (!buf)
314 return -ENOMEM;
315 if (copy_from_user(buf, user_buf, count)) {
316 free_page((unsigned long) buf);
317 return -EFAULT;
318 }
319 /* NULL-terminate and remove enter */
320 buf[count] = '\0';
321 strim(buf);
322
323 crashtype = find_crashtype(buf);
324 free_page((unsigned long) buf);
325 if (!crashtype)
326 return -EINVAL;
327
328 pr_info("Performing direct entry %s\n", crashtype->name);
329 lkdtm_do_action(crashtype);
330 *off += count;
331
332 return count;
333 }
334
335 #ifndef MODULE
336 /*
337 * To avoid needing to export parse_args(), just don't use this code
338 * when LKDTM is built as a module.
339 */
340 struct check_cmdline_args {
341 const char *param;
342 int value;
343 };
344
lkdtm_parse_one(char * param,char * val,const char * unused,void * arg)345 static int lkdtm_parse_one(char *param, char *val,
346 const char *unused, void *arg)
347 {
348 struct check_cmdline_args *args = arg;
349
350 /* short circuit if we already found a value. */
351 if (args->value != -ESRCH)
352 return 0;
353 if (strncmp(param, args->param, strlen(args->param)) == 0) {
354 bool bool_result;
355 int ret;
356
357 ret = kstrtobool(val, &bool_result);
358 if (ret == 0)
359 args->value = bool_result;
360 }
361 return 0;
362 }
363
lkdtm_check_bool_cmdline(const char * param)364 int lkdtm_check_bool_cmdline(const char *param)
365 {
366 char *command_line;
367 struct check_cmdline_args args = {
368 .param = param,
369 .value = -ESRCH,
370 };
371
372 command_line = kstrdup(saved_command_line, GFP_KERNEL);
373 if (!command_line)
374 return -ENOMEM;
375
376 parse_args("Setting sysctl args", command_line,
377 NULL, 0, -1, -1, &args, lkdtm_parse_one);
378
379 kfree(command_line);
380
381 return args.value;
382 }
383 #endif
384
385 static struct dentry *lkdtm_debugfs_root;
386
lkdtm_module_init(void)387 static int __init lkdtm_module_init(void)
388 {
389 struct crashpoint *crashpoint = NULL;
390 const struct crashtype *crashtype = NULL;
391 int ret;
392 int i;
393
394 /* Neither or both of these need to be set */
395 if ((cpoint_type || cpoint_name) && !(cpoint_type && cpoint_name)) {
396 pr_err("Need both cpoint_type and cpoint_name or neither\n");
397 return -EINVAL;
398 }
399
400 if (cpoint_type) {
401 crashtype = find_crashtype(cpoint_type);
402 if (!crashtype) {
403 pr_err("Unknown crashtype '%s'\n", cpoint_type);
404 return -EINVAL;
405 }
406 }
407
408 if (cpoint_name) {
409 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
410 if (!strcmp(cpoint_name, crashpoints[i].name))
411 crashpoint = &crashpoints[i];
412 }
413
414 /* Refuse unknown crashpoints. */
415 if (!crashpoint) {
416 pr_err("Invalid crashpoint %s\n", cpoint_name);
417 return -EINVAL;
418 }
419 }
420
421 #ifdef CONFIG_KPROBES
422 /* Set crash count. */
423 crash_count = cpoint_count;
424 #endif
425
426 /* Common initialization. */
427 lkdtm_kernel_info = kasprintf(GFP_KERNEL, "kernel (%s %s)",
428 init_uts_ns.name.release,
429 init_uts_ns.name.machine);
430
431 /* Handle test-specific initialization. */
432 lkdtm_bugs_init(&recur_count);
433 lkdtm_perms_init();
434 lkdtm_usercopy_init();
435 lkdtm_heap_init();
436
437 /* Register debugfs interface */
438 lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL);
439
440 /* Install debugfs trigger files. */
441 for (i = 0; i < ARRAY_SIZE(crashpoints); i++) {
442 struct crashpoint *cur = &crashpoints[i];
443
444 debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root, cur,
445 &cur->fops);
446 }
447
448 /* Install crashpoint if one was selected. */
449 if (crashpoint) {
450 ret = lkdtm_register_cpoint(crashpoint, crashtype);
451 if (ret < 0) {
452 pr_info("Invalid crashpoint %s\n", crashpoint->name);
453 goto out_err;
454 }
455 pr_info("Crash point %s of type %s registered\n",
456 crashpoint->name, cpoint_type);
457 } else {
458 pr_info("No crash points registered, enable through debugfs\n");
459 }
460
461 return 0;
462
463 out_err:
464 debugfs_remove_recursive(lkdtm_debugfs_root);
465 return ret;
466 }
467
lkdtm_module_exit(void)468 static void __exit lkdtm_module_exit(void)
469 {
470 debugfs_remove_recursive(lkdtm_debugfs_root);
471
472 /* Handle test-specific clean-up. */
473 lkdtm_heap_exit();
474 lkdtm_usercopy_exit();
475
476 if (lkdtm_kprobe != NULL)
477 unregister_kprobe(lkdtm_kprobe);
478
479 kfree(lkdtm_kernel_info);
480
481 pr_info("Crash point unregistered\n");
482 }
483
484 module_init(lkdtm_module_init);
485 module_exit(lkdtm_module_exit);
486
487 MODULE_LICENSE("GPL");
488 MODULE_DESCRIPTION("Kernel crash testing module");
489