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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 <[email protected]>
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 <[email protected]>
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
33static int lkdtm_debugfs_open(struct inode *inode, struct file *file);
34static ssize_t lkdtm_debugfs_read(struct file *f, char __user *user_buf,
35 size_t count, loff_t *off);
36static ssize_t direct_entry(struct file *f, const char __user *user_buf,
37 size_t count, loff_t *off);
38
39#ifdef CONFIG_KPROBES
40static int lkdtm_kprobe_handler(struct kprobe *kp, struct pt_regs *regs);
41static 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 */
57struct 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. */
76static 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. */
90static 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_BOOK3S_64
100 &powerpc_crashtypes,
101#endif
102};
103
104/* Global kprobe entry and crashtype. */
105static struct kprobe *lkdtm_kprobe;
106static struct crashpoint *lkdtm_crashpoint;
107static const struct crashtype *lkdtm_crashtype;
108
109/* Module parameters */
110static int recur_count = -1;
111module_param(recur_count, int, 0644);
112MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test");
113
114static char* cpoint_name;
115module_param(cpoint_name, charp, 0444);
116MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed");
117
118static char* cpoint_type;
119module_param(cpoint_type, charp, 0444);
120MODULE_PARM_DESC(cpoint_type, " Crash Point Type, action to be taken on "\
121 "hitting the crash point");
122
123static int cpoint_count = DEFAULT_COUNT;
124module_param(cpoint_count, int, 0644);
125MODULE_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 */
133char *lkdtm_kernel_info;
134
135/* Return the crashtype number or NULL if the name is invalid */
136static 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 */
160static 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
169static 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. */
198static int crash_count = DEFAULT_COUNT;
199static DEFINE_SPINLOCK(crash_count_lock);
200
201/* Called by kprobe entry points. */
202static 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
227static 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 */
267static 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
298static 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 */
304static 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 */
346struct check_cmdline_args {
347 const char *param;
348 int value;
349};
350
351static 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
370int 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
391static struct dentry *lkdtm_debugfs_root;
392
393static 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
469out_err:
470 debugfs_remove_recursive(lkdtm_debugfs_root);
471 return ret;
472}
473
474static 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
490module_init(lkdtm_module_init);
491module_exit(lkdtm_module_exit);
492
493MODULE_LICENSE("GPL");
494MODULE_DESCRIPTION("Kernel crash testing module");