1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * trace_events_inject - trace event injection
4 *
5 * Copyright (C) 2019 Cong Wang <cwang@twitter.com>
6 */
7
8 #include <linux/module.h>
9 #include <linux/ctype.h>
10 #include <linux/mutex.h>
11 #include <linux/slab.h>
12 #include <linux/rculist.h>
13
14 #include "trace.h"
15
16 static int
trace_inject_entry(struct trace_event_file * file,void * rec,int len)17 trace_inject_entry(struct trace_event_file *file, void *rec, int len)
18 {
19 struct trace_event_buffer fbuffer;
20 int written = 0;
21 void *entry;
22
23 rcu_read_lock_sched();
24 entry = trace_event_buffer_reserve(&fbuffer, file, len);
25 if (entry) {
26 memcpy(entry, rec, len);
27 written = len;
28 trace_event_buffer_commit(&fbuffer);
29 }
30 rcu_read_unlock_sched();
31
32 return written;
33 }
34
35 static int
parse_field(char * str,struct trace_event_call * call,struct ftrace_event_field ** pf,u64 * pv)36 parse_field(char *str, struct trace_event_call *call,
37 struct ftrace_event_field **pf, u64 *pv)
38 {
39 struct ftrace_event_field *field;
40 char *field_name;
41 int s, i = 0;
42 int len;
43 u64 val;
44
45 if (!str[i])
46 return 0;
47 /* First find the field to associate to */
48 while (isspace(str[i]))
49 i++;
50 s = i;
51 while (isalnum(str[i]) || str[i] == '_')
52 i++;
53 len = i - s;
54 if (!len)
55 return -EINVAL;
56
57 field_name = kmemdup_nul(str + s, len, GFP_KERNEL);
58 if (!field_name)
59 return -ENOMEM;
60 field = trace_find_event_field(call, field_name);
61 kfree(field_name);
62 if (!field)
63 return -ENOENT;
64
65 *pf = field;
66 while (isspace(str[i]))
67 i++;
68 if (str[i] != '=')
69 return -EINVAL;
70 i++;
71 while (isspace(str[i]))
72 i++;
73 s = i;
74 if (isdigit(str[i]) || str[i] == '-') {
75 char *num, c;
76 int ret;
77
78 /* Make sure the field is not a string */
79 if (is_string_field(field))
80 return -EINVAL;
81
82 if (str[i] == '-')
83 i++;
84
85 /* We allow 0xDEADBEEF */
86 while (isalnum(str[i]))
87 i++;
88 num = str + s;
89 c = str[i];
90 if (c != '\0' && !isspace(c))
91 return -EINVAL;
92 str[i] = '\0';
93 /* Make sure it is a value */
94 if (field->is_signed)
95 ret = kstrtoll(num, 0, &val);
96 else
97 ret = kstrtoull(num, 0, &val);
98 str[i] = c;
99 if (ret)
100 return ret;
101
102 *pv = val;
103 return i;
104 } else if (str[i] == '\'' || str[i] == '"') {
105 char q = str[i];
106
107 /* Make sure the field is OK for strings */
108 if (!is_string_field(field))
109 return -EINVAL;
110
111 for (i++; str[i]; i++) {
112 if (str[i] == '\\' && str[i + 1]) {
113 i++;
114 continue;
115 }
116 if (str[i] == q)
117 break;
118 }
119 if (!str[i])
120 return -EINVAL;
121
122 /* Skip quotes */
123 s++;
124 len = i - s;
125 if (len >= MAX_FILTER_STR_VAL)
126 return -EINVAL;
127
128 *pv = (unsigned long)(str + s);
129 str[i] = 0;
130 /* go past the last quote */
131 i++;
132 return i;
133 }
134
135 return -EINVAL;
136 }
137
trace_get_entry_size(struct trace_event_call * call)138 static int trace_get_entry_size(struct trace_event_call *call)
139 {
140 struct ftrace_event_field *field;
141 struct list_head *head;
142 int size = 0;
143
144 head = trace_get_fields(call);
145 list_for_each_entry(field, head, link) {
146 if (field->size + field->offset > size)
147 size = field->size + field->offset;
148 }
149
150 return size;
151 }
152
trace_alloc_entry(struct trace_event_call * call,int * size)153 static void *trace_alloc_entry(struct trace_event_call *call, int *size)
154 {
155 int entry_size = trace_get_entry_size(call);
156 struct ftrace_event_field *field;
157 struct list_head *head;
158 void *entry = NULL;
159
160 /* We need an extra '\0' at the end. */
161 entry = kzalloc(entry_size + 1, GFP_KERNEL);
162 if (!entry)
163 return NULL;
164
165 head = trace_get_fields(call);
166 list_for_each_entry(field, head, link) {
167 if (!is_string_field(field))
168 continue;
169 if (field->filter_type == FILTER_STATIC_STRING)
170 continue;
171 if (field->filter_type == FILTER_DYN_STRING ||
172 field->filter_type == FILTER_RDYN_STRING) {
173 u32 *str_item;
174 int str_loc = entry_size & 0xffff;
175
176 if (field->filter_type == FILTER_RDYN_STRING)
177 str_loc -= field->offset + field->size;
178
179 str_item = (u32 *)(entry + field->offset);
180 *str_item = str_loc; /* string length is 0. */
181 } else {
182 char **paddr;
183
184 paddr = (char **)(entry + field->offset);
185 *paddr = "";
186 }
187 }
188
189 *size = entry_size + 1;
190 return entry;
191 }
192
193 #define INJECT_STRING "STATIC STRING CAN NOT BE INJECTED"
194
195 /* Caller is responsible to free the *pentry. */
parse_entry(char * str,struct trace_event_call * call,void ** pentry)196 static int parse_entry(char *str, struct trace_event_call *call, void **pentry)
197 {
198 struct ftrace_event_field *field;
199 void *entry = NULL;
200 int entry_size;
201 u64 val = 0;
202 int len;
203
204 entry = trace_alloc_entry(call, &entry_size);
205 *pentry = entry;
206 if (!entry)
207 return -ENOMEM;
208
209 tracing_generic_entry_update(entry, call->event.type,
210 tracing_gen_ctx());
211
212 while ((len = parse_field(str, call, &field, &val)) > 0) {
213 if (is_function_field(field))
214 return -EINVAL;
215
216 if (is_string_field(field)) {
217 char *addr = (char *)(unsigned long) val;
218
219 if (field->filter_type == FILTER_STATIC_STRING) {
220 strscpy(entry + field->offset, addr, field->size);
221 } else if (field->filter_type == FILTER_DYN_STRING ||
222 field->filter_type == FILTER_RDYN_STRING) {
223 int str_len = strlen(addr) + 1;
224 int str_loc = entry_size & 0xffff;
225 u32 *str_item;
226
227 entry_size += str_len;
228 *pentry = krealloc(entry, entry_size, GFP_KERNEL);
229 if (!*pentry) {
230 kfree(entry);
231 return -ENOMEM;
232 }
233 entry = *pentry;
234
235 strscpy(entry + (entry_size - str_len), addr, str_len);
236 str_item = (u32 *)(entry + field->offset);
237 if (field->filter_type == FILTER_RDYN_STRING)
238 str_loc -= field->offset + field->size;
239 *str_item = (str_len << 16) | str_loc;
240 } else {
241 char **paddr;
242
243 paddr = (char **)(entry + field->offset);
244 *paddr = INJECT_STRING;
245 }
246 } else {
247 switch (field->size) {
248 case 1: {
249 u8 tmp = (u8) val;
250
251 memcpy(entry + field->offset, &tmp, 1);
252 break;
253 }
254 case 2: {
255 u16 tmp = (u16) val;
256
257 memcpy(entry + field->offset, &tmp, 2);
258 break;
259 }
260 case 4: {
261 u32 tmp = (u32) val;
262
263 memcpy(entry + field->offset, &tmp, 4);
264 break;
265 }
266 case 8:
267 memcpy(entry + field->offset, &val, 8);
268 break;
269 default:
270 return -EINVAL;
271 }
272 }
273
274 str += len;
275 }
276
277 if (len < 0)
278 return len;
279
280 return entry_size;
281 }
282
283 static ssize_t
event_inject_write(struct file * filp,const char __user * ubuf,size_t cnt,loff_t * ppos)284 event_inject_write(struct file *filp, const char __user *ubuf, size_t cnt,
285 loff_t *ppos)
286 {
287 struct trace_event_call *call;
288 struct trace_event_file *file;
289 int err = -ENODEV, size;
290 void *entry = NULL;
291 char *buf;
292
293 if (cnt >= PAGE_SIZE)
294 return -EINVAL;
295
296 buf = memdup_user_nul(ubuf, cnt);
297 if (IS_ERR(buf))
298 return PTR_ERR(buf);
299 strim(buf);
300
301 mutex_lock(&event_mutex);
302 file = event_file_file(filp);
303 if (file) {
304 call = file->event_call;
305 size = parse_entry(buf, call, &entry);
306 if (size < 0)
307 err = size;
308 else
309 err = trace_inject_entry(file, entry, size);
310 }
311 mutex_unlock(&event_mutex);
312
313 kfree(entry);
314 kfree(buf);
315
316 if (err < 0)
317 return err;
318
319 *ppos += err;
320 return cnt;
321 }
322
323 static ssize_t
event_inject_read(struct file * file,char __user * buf,size_t size,loff_t * ppos)324 event_inject_read(struct file *file, char __user *buf, size_t size,
325 loff_t *ppos)
326 {
327 return -EPERM;
328 }
329
330 const struct file_operations event_inject_fops = {
331 .open = tracing_open_file_tr,
332 .read = event_inject_read,
333 .write = event_inject_write,
334 .release = tracing_release_file_tr,
335 };
336