Commit | Line | Data |
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6f3a6fc5 MD |
1 | /* |
2 | * lttngtrace.c | |
3 | * | |
4 | * lttngtrace starts/stop system wide tracing around program execution. | |
5 | * | |
6 | * Copyright (c) 2010 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify | |
9 | * it under the terms of the GNU General Public License as published by | |
10 | * the Free Software Foundation; either version 2 of the License, or | |
11 | * (at your option) any later version. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | * | |
18 | * You should have received a copy of the GNU General Public License along | |
19 | * with this program; if not, write to the Free Software Foundation, Inc., | |
20 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
21 | * | |
22 | * This file should be setuid root, and belong to a "tracing" group. Only users | |
23 | * part of the tracing group can trace and view the traces gathered. | |
24 | * | |
25 | * TODO: LTTng should support per-session tracepoint activation. | |
26 | * TODO: use mkstemp() and save last trace name in user's home directory. | |
c94203ed | 27 | * TODO: drop priv + reenable standard signal handlers + call lttv at the end. |
432a1b04 MD |
28 | * TODO: -o option should be limited to creation of files in locations that the |
29 | * calling user has file creation access. | |
6f3a6fc5 MD |
30 | */ |
31 | ||
32 | #include <errno.h> | |
33 | #include <stdio.h> | |
34 | #include <fcntl.h> | |
35 | #include <signal.h> | |
36 | #include <unistd.h> | |
37 | #include <stdlib.h> | |
38 | #include <string.h> | |
39 | #include <limits.h> | |
40 | #include <dirent.h> | |
41 | #include <sys/wait.h> | |
42 | #include <sys/stat.h> | |
43 | #include <sys/types.h> | |
44 | ||
45 | #if DEBUG | |
46 | #define printf_dbg(fmt, args...) printf(fmt, args) | |
47 | #else | |
48 | #define printf_dbg(fmt, ...) | |
49 | #endif | |
50 | ||
51 | static char *trace_path; | |
52 | static char trace_path_pid[PATH_MAX]; | |
53 | static int autotrace; /* | |
54 | * Is the trace_path automatically chosen in /tmp ? Can | |
55 | * we unlink if needed ? | |
56 | */ | |
57 | static int sigfwd_pid; | |
8f48e913 MD |
58 | static char *progname = NULL; |
59 | ||
60 | void usage(void) { | |
61 | fprintf(stderr, "usage : %s [-o trace_name] command\n", progname); | |
62 | fprintf(stderr, "\nTracing tool for LTTng and UST\n\ | |
63 | \n\ | |
64 | Options:\n\ | |
65 | -o trace_name\t\tOutput file of the trace\n\ | |
66 | "); | |
67 | } | |
6f3a6fc5 MD |
68 | |
69 | static int recunlink(const char *dirname) | |
70 | { | |
71 | DIR *dir; | |
72 | struct dirent *entry; | |
73 | char path[PATH_MAX]; | |
74 | ||
75 | dir = opendir(dirname); | |
76 | if (dir == NULL) { | |
77 | if (errno == ENOENT) | |
78 | return 0; | |
79 | perror("Error opendir()"); | |
80 | return -errno; | |
81 | } | |
82 | ||
83 | while ((entry = readdir(dir)) != NULL) { | |
84 | if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")) { | |
85 | snprintf(path, (size_t) PATH_MAX, "%s/%s", dirname, | |
86 | entry->d_name); | |
87 | if (entry->d_type == DT_DIR) | |
88 | recunlink(path); | |
89 | else | |
90 | unlink(path); | |
91 | } | |
92 | } | |
93 | closedir(dir); | |
94 | rmdir(dirname); | |
95 | ||
96 | return 0; | |
97 | } | |
98 | ||
99 | static int start_tracing(void) | |
100 | { | |
101 | int ret; | |
102 | char command[PATH_MAX]; | |
103 | ||
104 | if (autotrace) { | |
105 | ret = recunlink(trace_path); | |
106 | if (ret) | |
107 | return ret; | |
108 | } | |
109 | ||
110 | /* | |
111 | * Create the directory in /tmp to deal with races (refuse if fail). | |
112 | * Only allow user and group to read the trace data (to limit | |
113 | * information disclosure). | |
114 | */ | |
115 | ret = mkdir(trace_path, S_IRWXU|S_IRWXG); | |
116 | if (ret) { | |
117 | perror("Trace directory creation error"); | |
118 | return ret; | |
119 | } | |
120 | ret = system("ltt-armall > /dev/null"); | |
121 | if (ret) | |
122 | return ret; | |
123 | ||
124 | ret = snprintf(command, PATH_MAX - 1, | |
125 | "lttctl -C -w %s autotrace1 > /dev/null", | |
126 | trace_path); | |
127 | ret = ret < 0 ? ret : 0; | |
128 | if (ret) | |
129 | return ret; | |
130 | ret = system(command); | |
131 | if (ret) | |
132 | return ret; | |
133 | } | |
134 | ||
135 | static int stop_tracing(uid_t uid, gid_t egid) | |
136 | { | |
137 | int ret; | |
138 | ||
139 | ret = system("lttctl -D autotrace1 > /dev/null"); | |
140 | if (ret) | |
141 | return ret; | |
142 | ret = system("ltt-disarmall > /dev/null"); | |
143 | if (ret) | |
144 | return ret; | |
145 | /* Hand the trace back to the user after tracing is over */ | |
146 | ret = chown(trace_path, uid, egid); | |
147 | if (ret) { | |
148 | perror("chown error"); | |
149 | return ret; | |
150 | } | |
151 | } | |
152 | ||
153 | static int write_child_pid(pid_t pid, uid_t uid, gid_t gid) | |
154 | { | |
155 | int fd; | |
156 | FILE *fp; | |
157 | int ret; | |
158 | ||
159 | /* Create the file as exclusive to deal with /tmp file creation races */ | |
160 | fd = open(trace_path_pid, O_WRONLY | O_CREAT | O_EXCL | O_TRUNC, | |
161 | S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP); | |
162 | fp = fdopen(fd, "w"); | |
163 | if (!fp) { | |
164 | perror("Error writing child pid"); | |
165 | return -errno; | |
166 | } | |
8f48e913 | 167 | |
6f3a6fc5 MD |
168 | fprintf(fp, "%u", (unsigned int) pid); |
169 | ret = fclose(fp); | |
170 | if (ret) | |
171 | perror("Error in fclose"); | |
172 | /* Hand pid information file back to user */ | |
173 | ret = chown(trace_path_pid, uid, gid); | |
174 | if (ret) | |
175 | perror("chown error"); | |
176 | return ret; | |
177 | } | |
178 | ||
8f48e913 | 179 | static int parse_options(int argc, char **argv, int *arg) |
6f3a6fc5 | 180 | { |
8f48e913 MD |
181 | int i, c; |
182 | ||
183 | while ((c = getopt(argc, argv, "ho:")) != -1) { | |
184 | switch (c) { | |
185 | case 'o': | |
186 | trace_path = strdup(optarg); | |
6f3a6fc5 | 187 | break; |
8f48e913 MD |
188 | case 'h': |
189 | usage(); | |
190 | exit(EXIT_SUCCESS); | |
191 | case '?': | |
192 | usage(); | |
193 | exit(EXIT_FAILURE); | |
194 | default: | |
195 | exit(EXIT_FAILURE); | |
6f3a6fc5 MD |
196 | } |
197 | } | |
8f48e913 MD |
198 | |
199 | if (argc - optind > 0) { | |
200 | for (i = optind + 1; i < argc; i++) { | |
201 | printf ("Non-option argument %s\n", argv[i]); | |
202 | } | |
203 | } else { | |
204 | usage(); | |
205 | exit(EXIT_FAILURE); | |
206 | } | |
207 | ||
208 | *arg = optind; | |
209 | ||
210 | return 0; | |
6f3a6fc5 MD |
211 | } |
212 | ||
213 | static int init_trace_path(void) | |
214 | { | |
215 | int ret; | |
216 | ||
217 | if (!trace_path) { | |
218 | trace_path = "/tmp/autotrace1"; | |
219 | autotrace = 1; | |
220 | } | |
221 | ret = snprintf(trace_path_pid, PATH_MAX - 1, "%s/%s", | |
222 | trace_path, "pid"); | |
223 | ret = ret < 0 ? ret : 0; | |
224 | return ret; | |
225 | } | |
226 | ||
227 | static void sighandler(int signo, siginfo_t *siginfo, void *context) | |
228 | { | |
229 | kill(sigfwd_pid, signo); | |
230 | } | |
231 | ||
232 | static int init_sighand(sigset_t *saved_mask) | |
233 | { | |
234 | sigset_t sig_all_mask; | |
235 | int gret = 0, ret; | |
236 | ||
237 | /* Block signals */ | |
238 | ret = sigfillset(&sig_all_mask); | |
239 | if (ret) | |
240 | perror("Error in sigfillset"); | |
241 | gret = (gret == 0) ? ret : gret; | |
242 | ret = sigprocmask(SIG_SETMASK, &sig_all_mask, saved_mask); | |
243 | if (ret) | |
244 | perror("Error in sigprocmask"); | |
245 | gret = (gret == 0) ? ret : gret; | |
246 | return gret; | |
247 | } | |
248 | ||
249 | static int forward_signals(pid_t pid, sigset_t *saved_mask) | |
250 | { | |
251 | struct sigaction act; | |
252 | int gret = 0, ret; | |
253 | ||
254 | /* Forward SIGINT and SIGTERM */ | |
255 | sigfwd_pid = pid; | |
256 | act.sa_sigaction = sighandler; | |
257 | act.sa_flags = SA_SIGINFO | SA_RESTART; | |
258 | sigemptyset(&act.sa_mask); | |
259 | ret = sigaction(SIGINT, &act, NULL); | |
260 | if (ret) | |
261 | perror("Error in sigaction"); | |
262 | gret = (gret == 0) ? ret : gret; | |
263 | ret = sigaction(SIGTERM, &act, NULL); | |
264 | if (ret) | |
265 | perror("Error in sigaction"); | |
266 | gret = (gret == 0) ? ret : gret; | |
267 | ||
268 | /* Reenable signals */ | |
269 | ret = sigprocmask(SIG_SETMASK, saved_mask, NULL); | |
270 | if (ret) | |
271 | perror("Error in sigprocmask"); | |
272 | gret = (gret == 0) ? ret : gret; | |
273 | return gret; | |
274 | } | |
275 | ||
276 | int main(int argc, char *argv[]) | |
277 | { | |
278 | uid_t euid, uid; | |
279 | gid_t egid, gid; | |
280 | pid_t pid; | |
281 | int gret = 0, ret = 0; | |
282 | int arg = 1; | |
283 | sigset_t saved_mask; | |
284 | ||
8f48e913 MD |
285 | progname = argv[0]; |
286 | ||
287 | if (argc < 2) { | |
288 | usage(); | |
6f3a6fc5 | 289 | return -ENOENT; |
8f48e913 | 290 | } |
6f3a6fc5 MD |
291 | |
292 | euid = geteuid(); | |
293 | uid = getuid(); | |
294 | egid = getegid(); | |
295 | gid = geteuid(); | |
296 | ||
297 | if (euid != 0 && uid != 0) { | |
8f48e913 | 298 | printf("%s must be setuid root\n", progname); |
6f3a6fc5 MD |
299 | return -EPERM; |
300 | } | |
301 | ||
302 | printf_dbg("euid: %d\n", euid); | |
303 | printf_dbg("uid: %d\n", uid); | |
304 | printf_dbg("egid: %d\n", egid); | |
305 | printf_dbg("gid: %d\n", gid); | |
306 | ||
8f48e913 MD |
307 | ret = parse_options(argc, argv, &arg); |
308 | if (ret) | |
309 | return ret; | |
6f3a6fc5 MD |
310 | |
311 | ret = init_trace_path(); | |
312 | gret = (gret == 0) ? ret : gret; | |
313 | ||
314 | ret = init_sighand(&saved_mask); | |
315 | gret = (gret == 0) ? ret : gret; | |
316 | ||
317 | ret = start_tracing(); | |
318 | if (ret) | |
319 | return ret; | |
320 | ||
321 | pid = fork(); | |
322 | if (pid > 0) { /* parent */ | |
323 | int status; | |
324 | ||
325 | ret = forward_signals(pid, &saved_mask); | |
326 | gret = (gret == 0) ? ret : gret; | |
327 | pid = wait(&status); | |
328 | if (pid == -1) | |
329 | gret = (gret == 0) ? -errno : gret; | |
330 | ||
331 | ret = stop_tracing(uid, egid); | |
332 | gret = (gret == 0) ? ret : gret; | |
333 | ret = write_child_pid(pid, uid, egid); | |
334 | gret = (gret == 0) ? ret : gret; | |
335 | } else if (pid == 0) { /* child */ | |
336 | /* Drop root euid before executing child program */ | |
337 | seteuid(uid); | |
338 | /* Reenable signals */ | |
339 | ret = sigprocmask(SIG_SETMASK, &saved_mask, NULL); | |
340 | if (ret) { | |
341 | perror("Error in sigprocmask"); | |
342 | return ret; | |
343 | } | |
344 | ret = execvp(argv[arg], &argv[arg]); | |
345 | if (ret) | |
346 | perror("Execution error"); | |
347 | return ret; | |
348 | } else { /* error */ | |
349 | perror("Error in fork"); | |
350 | return -errno; | |
351 | } | |
352 | return ret; | |
353 | } |