summaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_events_inject.c
blob: d45079ee62f8d9a75e53c616dd8b498d9ecbdd11 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
// SPDX-License-Identifier: GPL-2.0
/*
 * trace_events_inject - trace event injection
 *
 * Copyright (C) 2019 Cong Wang <cwang@twitter.com>
 */

#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <linux/rculist.h>

#include "trace.h"

static int
trace_inject_entry(struct trace_event_file *file, void *rec, int len)
{
	struct trace_event_buffer fbuffer;
	int written = 0;
	void *entry;

	rcu_read_lock_sched();
	entry = trace_event_buffer_reserve(&fbuffer, file, len);
	if (entry) {
		memcpy(entry, rec, len);
		written = len;
		trace_event_buffer_commit(&fbuffer);
	}
	rcu_read_unlock_sched();

	return written;
}

static int
parse_field(char *str, struct trace_event_call *call,
	    struct ftrace_event_field **pf, u64 *pv)
{
	struct ftrace_event_field *field;
	char *field_name;
	int s, i = 0;
	int len;
	u64 val;

	if (!str[i])
		return 0;
	/* First find the field to associate to */
	while (isspace(str[i]))
		i++;
	s = i;
	while (isalnum(str[i]) || str[i] == '_')
		i++;
	len = i - s;
	if (!len)
		return -EINVAL;

	field_name = kmemdup_nul(str + s, len, GFP_KERNEL);
	if (!field_name)
		return -ENOMEM;
	field = trace_find_event_field(call, field_name);
	kfree(field_name);
	if (!field)
		return -ENOENT;

	*pf = field;
	while (isspace(str[i]))
		i++;
	if (str[i] != '=')
		return -EINVAL;
	i++;
	while (isspace(str[i]))
		i++;
	s = i;
	if (isdigit(str[i]) || str[i] == '-') {
		char *num, c;
		int ret;

		/* Make sure the field is not a string */
		if (is_string_field(field))
			return -EINVAL;

		if (str[i] == '-')
			i++;

		/* We allow 0xDEADBEEF */
		while (isalnum(str[i]))
			i++;
		num = str + s;
		c = str[i];
		if (c != '\0' && !isspace(c))
			return -EINVAL;
		str[i] = '\0';
		/* Make sure it is a value */
		if (field->is_signed)
			ret = kstrtoll(num, 0, &val);
		else
			ret = kstrtoull(num, 0, &val);
		str[i] = c;
		if (ret)
			return ret;

		*pv = val;
		return i;
	} else if (str[i] == '\'' || str[i] == '"') {
		char q = str[i];

		/* Make sure the field is OK for strings */
		if (!is_string_field(field))
			return -EINVAL;

		for (i++; str[i]; i++) {
			if (str[i] == '\\' && str[i + 1]) {
				i++;
				continue;
			}
			if (str[i] == q)
				break;
		}
		if (!str[i])
			return -EINVAL;

		/* Skip quotes */
		s++;
		len = i - s;
		if (len >= MAX_FILTER_STR_VAL)
			return -EINVAL;

		*pv = (unsigned long)(str + s);
		str[i] = 0;
		/* go past the last quote */
		i++;
		return i;
	}

	return -EINVAL;
}

static int trace_get_entry_size(struct trace_event_call *call)
{
	struct ftrace_event_field *field;
	struct list_head *head;
	int size = 0;

	head = trace_get_fields(call);
	list_for_each_entry(field, head, link) {
		if (field->size + field->offset > size)
			size = field->size + field->offset;
	}

	return size;
}

static void *trace_alloc_entry(struct trace_event_call *call, int *size)
{
	int entry_size = trace_get_entry_size(call);
	struct ftrace_event_field *field;
	struct list_head *head;
	void *entry = NULL;

	/* We need an extra '\0' at the end. */
	entry = kzalloc(entry_size + 1, GFP_KERNEL);
	if (!entry)
		return NULL;

	head = trace_get_fields(call);
	list_for_each_entry(field, head, link) {
		if (!is_string_field(field))
			continue;
		if (field->filter_type == FILTER_STATIC_STRING)
			continue;
		if (field->filter_type == FILTER_DYN_STRING) {
			u32 *str_item;
			int str_loc = entry_size & 0xffff;

			str_item = (u32 *)(entry + field->offset);
			*str_item = str_loc; /* string length is 0. */
		} else {
			char **paddr;

			paddr = (char **)(entry + field->offset);
			*paddr = "";
		}
	}

	*size = entry_size + 1;
	return entry;
}

#define INJECT_STRING "STATIC STRING CAN NOT BE INJECTED"

/* Caller is responsible to free the *pentry. */
static int parse_entry(char *str, struct trace_event_call *call, void **pentry)
{
	struct ftrace_event_field *field;
	unsigned long irq_flags;
	void *entry = NULL;
	int entry_size;
	u64 val;
	int len;

	entry = trace_alloc_entry(call, &entry_size);
	*pentry = entry;
	if (!entry)
		return -ENOMEM;

	local_save_flags(irq_flags);
	tracing_generic_entry_update(entry, call->event.type, irq_flags,
				     preempt_count());

	while ((len = parse_field(str, call, &field, &val)) > 0) {
		if (is_function_field(field))
			return -EINVAL;

		if (is_string_field(field)) {
			char *addr = (char *)(unsigned long) val;

			if (field->filter_type == FILTER_STATIC_STRING) {
				strlcpy(entry + field->offset, addr, field->size);
			} else if (field->filter_type == FILTER_DYN_STRING) {
				int str_len = strlen(addr) + 1;
				int str_loc = entry_size & 0xffff;
				u32 *str_item;

				entry_size += str_len;
				*pentry = krealloc(entry, entry_size, GFP_KERNEL);
				if (!*pentry) {
					kfree(entry);
					return -ENOMEM;
				}
				entry = *pentry;

				strlcpy(entry + (entry_size - str_len), addr, str_len);
				str_item = (u32 *)(entry + field->offset);
				*str_item = (str_len << 16) | str_loc;
			} else {
				char **paddr;

				paddr = (char **)(entry + field->offset);
				*paddr = INJECT_STRING;
			}
		} else {
			switch (field->size) {
			case 1: {
				u8 tmp = (u8) val;

				memcpy(entry + field->offset, &tmp, 1);
				break;
			}
			case 2: {
				u16 tmp = (u16) val;

				memcpy(entry + field->offset, &tmp, 2);
				break;
			}
			case 4: {
				u32 tmp = (u32) val;

				memcpy(entry + field->offset, &tmp, 4);
				break;
			}
			case 8:
				memcpy(entry + field->offset, &val, 8);
				break;
			default:
				return -EINVAL;
			}
		}

		str += len;
	}

	if (len < 0)
		return len;

	return entry_size;
}

static ssize_t
event_inject_write(struct file *filp, const char __user *ubuf, size_t cnt,
		   loff_t *ppos)
{
	struct trace_event_call *call;
	struct trace_event_file *file;
	int err = -ENODEV, size;
	void *entry = NULL;
	char *buf;

	if (cnt >= PAGE_SIZE)
		return -EINVAL;

	buf = memdup_user_nul(ubuf, cnt);
	if (IS_ERR(buf))
		return PTR_ERR(buf);
	strim(buf);

	mutex_lock(&event_mutex);
	file = event_file_data(filp);
	if (file) {
		call = file->event_call;
		size = parse_entry(buf, call, &entry);
		if (size < 0)
			err = size;
		else
			err = trace_inject_entry(file, entry, size);
	}
	mutex_unlock(&event_mutex);

	kfree(entry);
	kfree(buf);

	if (err < 0)
		return err;

	*ppos += err;
	return cnt;
}

static ssize_t
event_inject_read(struct file *file, char __user *buf, size_t size,
		  loff_t *ppos)
{
	return -EPERM;
}

const struct file_operations event_inject_fops = {
	.open = tracing_open_generic,
	.read = event_inject_read,
	.write = event_inject_write,
};