xref: /openbmc/linux/drivers/misc/lkdtm/core.c (revision b290df06)
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_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. */
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