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
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_64S_HASH_MMU
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");
495