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0c4e727b JR |
1 | /* |
2 | * Copyright (C) 2020 EfficiOS, Inc. | |
3 | * | |
4 | * SPDX-License-Identifier: GPL-2.0-only | |
5 | * | |
6 | */ | |
7 | ||
8 | #include "uprobe.h" | |
9 | ||
10 | #include <sys/types.h> | |
11 | #include <sys/stat.h> | |
12 | #include <unistd.h> | |
13 | ||
14 | #include "common/compat/getenv.h" | |
15 | #include "common/string-utils/string-utils.h" | |
16 | #include "common/utils.h" | |
4971b7f0 | 17 | #include "common/path.h" |
0c4e727b JR |
18 | #include "lttng/constant.h" |
19 | ||
20 | #include "command.h" | |
21 | ||
22 | /* | |
23 | * Walk the directories in the PATH environment variable to find the target | |
24 | * binary passed as parameter. | |
25 | * | |
26 | * On success, the full path of the binary is copied in binary_full_path out | |
27 | * parameter. This buffer is allocated by the caller and must be at least | |
28 | * LTTNG_PATH_MAX bytes long. | |
29 | * On failure, returns -1; | |
30 | */ | |
31 | static | |
32 | int walk_command_search_path(const char *binary, char *binary_full_path) | |
33 | { | |
34 | char *tentative_binary_path = NULL; | |
35 | char *command_search_path = NULL; | |
36 | char *curr_search_dir_end = NULL; | |
37 | char *curr_search_dir = NULL; | |
38 | struct stat stat_output; | |
39 | int ret = 0; | |
40 | ||
41 | command_search_path = lttng_secure_getenv("PATH"); | |
42 | if (!command_search_path) { | |
43 | ret = -1; | |
44 | goto end; | |
45 | } | |
46 | ||
47 | /* | |
48 | * Duplicate the $PATH string as the char pointer returned by getenv() should | |
49 | * not be modified. | |
50 | */ | |
51 | command_search_path = strdup(command_search_path); | |
52 | if (!command_search_path) { | |
53 | ret = -1; | |
54 | goto end; | |
55 | } | |
56 | ||
57 | /* | |
58 | * This char array is used to concatenate path to binary to look for | |
59 | * the binary. | |
60 | */ | |
48a40005 | 61 | tentative_binary_path = (char *) zmalloc(LTTNG_PATH_MAX * sizeof(char)); |
0c4e727b JR |
62 | if (!tentative_binary_path) { |
63 | ret = -1; | |
64 | goto alloc_error; | |
65 | } | |
66 | ||
67 | curr_search_dir = command_search_path; | |
68 | do { | |
69 | /* | |
70 | * Split on ':'. The return value of this call points to the | |
71 | * matching character. | |
72 | */ | |
73 | curr_search_dir_end = strchr(curr_search_dir, ':'); | |
74 | if (curr_search_dir_end != NULL) { | |
75 | /* | |
76 | * Add a NULL byte to the end of the first token so it | |
77 | * can be used as a string. | |
78 | */ | |
79 | curr_search_dir_end[0] = '\0'; | |
80 | } | |
81 | ||
82 | /* Empty the tentative path */ | |
83 | memset(tentative_binary_path, 0, LTTNG_PATH_MAX * sizeof(char)); | |
84 | ||
85 | /* | |
86 | * Build the tentative path to the binary using the current | |
87 | * search directory and the name of the binary. | |
88 | */ | |
89 | ret = snprintf(tentative_binary_path, LTTNG_PATH_MAX, "%s/%s", | |
90 | curr_search_dir, binary); | |
91 | if (ret < 0) { | |
92 | goto free_binary_path; | |
93 | } | |
94 | if (ret < LTTNG_PATH_MAX) { | |
95 | /* | |
96 | * Use STAT(2) to see if the file exists. | |
97 | */ | |
98 | ret = stat(tentative_binary_path, &stat_output); | |
99 | if (ret == 0) { | |
100 | /* | |
101 | * Verify that it is a regular file or a | |
102 | * symlink and not a special file (e.g. | |
103 | * device). | |
104 | */ | |
105 | if (S_ISREG(stat_output.st_mode) | |
106 | || S_ISLNK(stat_output.st_mode)) { | |
107 | /* | |
108 | * Found a match, set the out parameter | |
109 | * and return success. | |
110 | */ | |
111 | ret = lttng_strncpy(binary_full_path, | |
112 | tentative_binary_path, | |
113 | LTTNG_PATH_MAX); | |
114 | if (ret == -1) { | |
115 | ERR("Source path does not fit " | |
116 | "in destination buffer."); | |
117 | } | |
118 | goto free_binary_path; | |
119 | } | |
120 | } | |
121 | } | |
122 | /* Go to the next entry in the $PATH variable. */ | |
123 | curr_search_dir = curr_search_dir_end + 1; | |
124 | } while (curr_search_dir_end != NULL); | |
125 | ||
126 | free_binary_path: | |
127 | free(tentative_binary_path); | |
128 | alloc_error: | |
129 | free(command_search_path); | |
130 | end: | |
131 | return ret; | |
132 | } | |
133 | ||
134 | /* | |
135 | * Check if the symbol field passed by the user is in fact an address or an | |
136 | * offset from a symbol. Those two instrumentation types are not supported yet. | |
137 | * It's expected to be a common mistake because of the existing --probe option | |
138 | * that does support these formats. | |
139 | * | |
140 | * Here are examples of these unsupported formats for the --userspace-probe | |
141 | * option: | |
142 | * elf:/path/to/binary:0x400430 | |
143 | * elf:/path/to/binary:4194364 | |
144 | * elf:/path/to/binary:my_symbol+0x323 | |
145 | * elf:/path/to/binary:my_symbol+43 | |
146 | */ | |
147 | static | |
148 | int warn_userspace_probe_syntax(const char *symbol) | |
149 | { | |
150 | int ret; | |
151 | ||
152 | /* Check if the symbol field is an hex address. */ | |
153 | ret = sscanf(symbol, "0x%*x"); | |
154 | if (ret > 0) { | |
155 | /* If there is a match, print a warning and return an error. */ | |
156 | ERR("Userspace probe on address not supported yet."); | |
157 | ret = CMD_UNSUPPORTED; | |
158 | goto error; | |
159 | } | |
160 | ||
161 | /* Check if the symbol field is an decimal address. */ | |
162 | ret = sscanf(symbol, "%*u"); | |
163 | if (ret > 0) { | |
164 | /* If there is a match, print a warning and return an error. */ | |
165 | ERR("Userspace probe on address not supported yet."); | |
166 | ret = CMD_UNSUPPORTED; | |
167 | goto error; | |
168 | } | |
169 | ||
170 | /* Check if the symbol field is symbol+hex_offset. */ | |
171 | ret = sscanf(symbol, "%*[^+]+0x%*x"); | |
172 | if (ret > 0) { | |
173 | /* If there is a match, print a warning and return an error. */ | |
174 | ERR("Userspace probe on symbol+offset not supported yet."); | |
175 | ret = CMD_UNSUPPORTED; | |
176 | goto error; | |
177 | } | |
178 | ||
179 | /* Check if the symbol field is symbol+decimal_offset. */ | |
180 | ret = sscanf(symbol, "%*[^+]+%*u"); | |
181 | if (ret > 0) { | |
182 | /* If there is a match, print a warning and return an error. */ | |
183 | ERR("Userspace probe on symbol+offset not supported yet."); | |
184 | ret = CMD_UNSUPPORTED; | |
185 | goto error; | |
186 | } | |
187 | ||
188 | ret = 0; | |
189 | ||
190 | error: | |
191 | return ret; | |
192 | } | |
193 | ||
194 | /* | |
195 | * Parse userspace probe options | |
196 | * Set the userspace probe fields in the lttng_event struct and set the | |
197 | * target_path to the path to the binary. | |
198 | */ | |
0c4e727b JR |
199 | int parse_userspace_probe_opts(const char *opt, |
200 | struct lttng_userspace_probe_location **probe_location) | |
201 | { | |
202 | int ret = CMD_SUCCESS; | |
e358ddd5 | 203 | size_t num_token = 0; |
0c4e727b JR |
204 | char *target_path = NULL; |
205 | char *unescaped_target_path = NULL; | |
206 | char *real_target_path = NULL; | |
207 | char *symbol_name = NULL, *probe_name = NULL, *provider_name = NULL; | |
208 | struct lttng_userspace_probe_location *probe_location_local = NULL; | |
209 | struct lttng_userspace_probe_location_lookup_method *lookup_method = NULL; | |
e358ddd5 | 210 | struct lttng_dynamic_pointer_array tokens; |
0c4e727b | 211 | |
a0377dfe | 212 | LTTNG_ASSERT(opt); |
0c4e727b JR |
213 | |
214 | /* | |
215 | * userspace probe fields are separated by ':'. | |
216 | */ | |
e358ddd5 JG |
217 | ret = strutils_split(opt, ':', true, &tokens); |
218 | if (ret == 0) { | |
219 | num_token = lttng_dynamic_pointer_array_get_count(&tokens); | |
220 | } | |
0c4e727b JR |
221 | |
222 | /* | |
223 | * Early sanity check that the number of parameter is between 2 and 4 | |
224 | * inclusively. | |
225 | * elf:PATH:SYMBOL | |
226 | * std:PATH:PROVIDER_NAME:PROBE_NAME | |
227 | * PATH:SYMBOL (same behavior as ELF) | |
228 | */ | |
e358ddd5 | 229 | if (ret < 0 || num_token < 2 || num_token > 4) { |
0c4e727b JR |
230 | ret = CMD_ERROR; |
231 | goto end; | |
232 | } | |
233 | ||
234 | /* | |
235 | * Looking up the first parameter will tell the technique to use to | |
236 | * interpret the userspace probe/function description. | |
237 | */ | |
238 | switch (num_token) { | |
239 | case 2: | |
240 | /* When the probe type is omitted we assume ELF for now. */ | |
241 | case 3: | |
48a40005 SM |
242 | if (num_token == 3 && strcmp((const char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 0), "elf") == 0) { |
243 | target_path = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 1); | |
244 | symbol_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 2); | |
0c4e727b | 245 | } else if (num_token == 2) { |
48a40005 SM |
246 | target_path = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 0); |
247 | symbol_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 1); | |
0c4e727b JR |
248 | } else { |
249 | ret = CMD_ERROR; | |
250 | goto end; | |
251 | } | |
252 | lookup_method = | |
253 | lttng_userspace_probe_location_lookup_method_function_elf_create(); | |
254 | if (!lookup_method) { | |
255 | WARN("Failed to create ELF lookup method"); | |
256 | ret = CMD_ERROR; | |
257 | goto end; | |
258 | } | |
259 | break; | |
260 | case 4: | |
48a40005 SM |
261 | if (strcmp((const char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 0), "sdt") == 0) { |
262 | target_path = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 1); | |
263 | provider_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 2); | |
264 | probe_name = (char *) lttng_dynamic_pointer_array_get_pointer(&tokens, 3); | |
0c4e727b JR |
265 | } else { |
266 | ret = CMD_ERROR; | |
267 | goto end; | |
268 | } | |
269 | lookup_method = | |
270 | lttng_userspace_probe_location_lookup_method_tracepoint_sdt_create(); | |
271 | if (!lookup_method) { | |
272 | WARN("Failed to create SDT lookup method"); | |
273 | ret = CMD_ERROR; | |
274 | goto end; | |
275 | } | |
276 | break; | |
277 | default: | |
278 | ret = CMD_ERROR; | |
279 | goto end; | |
280 | } | |
281 | ||
282 | /* strutils_unescape_string allocates a new char *. */ | |
283 | unescaped_target_path = strutils_unescape_string(target_path, 0); | |
284 | if (!unescaped_target_path) { | |
285 | ret = CMD_ERROR; | |
286 | goto end; | |
287 | } | |
288 | ||
289 | /* | |
290 | * If there is not forward slash in the path. Walk the $PATH else | |
291 | * expand. | |
292 | */ | |
293 | if (strchr(unescaped_target_path, '/') == NULL) { | |
294 | /* Walk the $PATH variable to find the targeted binary. */ | |
48a40005 | 295 | real_target_path = (char *) zmalloc(LTTNG_PATH_MAX * sizeof(char)); |
0c4e727b JR |
296 | if (!real_target_path) { |
297 | PERROR("Error allocating path buffer"); | |
298 | ret = CMD_ERROR; | |
299 | goto end; | |
300 | } | |
301 | ret = walk_command_search_path(unescaped_target_path, real_target_path); | |
302 | if (ret) { | |
303 | ERR("Binary not found."); | |
304 | ret = CMD_ERROR; | |
305 | goto end; | |
306 | } | |
307 | } else { | |
308 | /* | |
309 | * Expand references to `/./` and `/../`. This function does not check | |
310 | * if the file exists. This call returns an allocated buffer on | |
311 | * success. | |
312 | */ | |
313 | real_target_path = utils_expand_path_keep_symlink(unescaped_target_path); | |
314 | if (!real_target_path) { | |
315 | ERR("Error expanding the path to binary."); | |
316 | ret = CMD_ERROR; | |
317 | goto end; | |
318 | } | |
319 | ||
320 | /* | |
321 | * Check if the file exists using access(2), If it does not, | |
322 | * return an error. | |
323 | */ | |
324 | ret = access(real_target_path, F_OK); | |
325 | if (ret) { | |
326 | ERR("Cannot find binary at path: %s.", real_target_path); | |
327 | ret = CMD_ERROR; | |
328 | goto end; | |
329 | } | |
330 | } | |
331 | ||
332 | switch (lttng_userspace_probe_location_lookup_method_get_type(lookup_method)) { | |
333 | case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF: | |
334 | /* | |
335 | * Check for common mistakes in userspace probe description syntax. | |
336 | */ | |
337 | ret = warn_userspace_probe_syntax(symbol_name); | |
338 | if (ret) { | |
339 | goto end; | |
340 | } | |
341 | ||
342 | probe_location_local = lttng_userspace_probe_location_function_create( | |
343 | real_target_path, symbol_name, lookup_method); | |
344 | if (!probe_location_local) { | |
345 | WARN("Failed to create function probe location"); | |
346 | ret = CMD_ERROR; | |
347 | goto end; | |
348 | } | |
349 | ||
350 | /* Ownership transferred to probe_location. */ | |
351 | lookup_method = NULL; | |
352 | break; | |
353 | case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT: | |
354 | probe_location_local = lttng_userspace_probe_location_tracepoint_create( | |
355 | real_target_path, provider_name, probe_name, lookup_method); | |
356 | if (!probe_location_local) { | |
357 | WARN("Failed to create function probe location"); | |
358 | ret = CMD_ERROR; | |
359 | goto end; | |
360 | } | |
361 | ||
362 | /* Ownership transferred to probe_location. */ | |
363 | lookup_method = NULL; | |
364 | break; | |
365 | default: | |
366 | ret = CMD_ERROR; | |
367 | goto end; | |
368 | } | |
369 | ||
370 | /* | |
371 | * Everything went fine, transfer ownership of probe location to | |
372 | * caller. | |
373 | */ | |
374 | *probe_location = probe_location_local; | |
375 | probe_location_local = NULL; | |
376 | ||
377 | end: | |
378 | lttng_userspace_probe_location_destroy(probe_location_local); | |
379 | lttng_userspace_probe_location_lookup_method_destroy(lookup_method); | |
e358ddd5 | 380 | lttng_dynamic_pointer_array_reset(&tokens); |
0c4e727b JR |
381 | /* |
382 | * Freeing both char * here makes the error handling simplier. free() | |
383 | * performs not action if the pointer is NULL. | |
384 | */ | |
385 | free(real_target_path); | |
386 | free(unescaped_target_path); | |
387 | ||
388 | return ret; | |
389 | } |