Commit | Line | Data |
---|---|---|
059ec3d9 PH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | ||
3386088d | 5 | /* Copyright (c) University of Cambridge 1995 - 2015 */ |
059ec3d9 PH |
6 | /* See the file NOTICE for conditions of use and distribution. */ |
7 | ||
8 | ||
9 | #include "exim.h" | |
10 | ||
11 | static void (*oldsignal)(int); | |
12 | ||
13 | ||
14 | /************************************************* | |
15 | * Ensure an fd has a given value * | |
16 | *************************************************/ | |
17 | ||
18 | /* This function is called when we want to ensure that a certain fd has a | |
19 | specific value (one of 0, 1, 2). If it hasn't got it already, close the value | |
20 | we want, duplicate the fd, then close the old one. | |
21 | ||
22 | Arguments: | |
23 | oldfd original fd | |
24 | newfd the fd we want | |
25 | ||
26 | Returns: nothing | |
27 | */ | |
28 | ||
29 | static void | |
30 | force_fd(int oldfd, int newfd) | |
31 | { | |
32 | if (oldfd == newfd) return; | |
f1e894f3 PH |
33 | (void)close(newfd); |
34 | (void)dup2(oldfd, newfd); | |
35 | (void)close(oldfd); | |
059ec3d9 PH |
36 | } |
37 | ||
38 | ||
e7726cbf | 39 | #ifndef STAND_ALONE |
059ec3d9 PH |
40 | /************************************************* |
41 | * Build argv list and optionally re-exec Exim * | |
42 | *************************************************/ | |
43 | ||
44 | /* This function is called when Exim wants to re-exec (overlay) itself in the | |
45 | current process. This is different to child_open_exim(), which runs another | |
46 | Exim process in parallel (but it then calls this function). The function's | |
47 | basic job is to build the argv list according to the values of current options | |
48 | settings. There is a basic list that all calls require, and an additional list | |
49 | that some do not require. Further additions can be given as additional | |
50 | arguments. An option specifies whether the exec() is actually to happen, and if | |
51 | so, what is to be done if it fails. | |
52 | ||
53 | Arguments: | |
54 | exec_type CEE_RETURN_ARGV => don't exec; return the argv list | |
55 | CEE_EXEC_EXIT => just exit() on exec failure | |
56 | CEE_EXEC_PANIC => panic-die on exec failure | |
57 | kill_v if TRUE, don't pass on the D_v flag | |
58 | pcount if not NULL, points to extra size of argv required, and if | |
59 | CEE_RETURN_ARGV is specified, it is updated to give the | |
60 | number of slots used | |
61 | minimal TRUE if only minimal argv is required | |
62 | acount number of additional arguments | |
63 | ... further values to add to argv | |
64 | ||
65 | Returns: if CEE_RETURN_ARGV is given, returns a pointer to argv; | |
66 | otherwise, does not return | |
67 | */ | |
68 | ||
69 | uschar ** | |
70 | child_exec_exim(int exec_type, BOOL kill_v, int *pcount, BOOL minimal, | |
71 | int acount, ...) | |
72 | { | |
73 | int first_special = -1; | |
74 | int n = 0; | |
e37f8a84 | 75 | int extra = pcount ? *pcount : 0; |
059ec3d9 | 76 | uschar **argv = |
e37f8a84 | 77 | store_get((extra + acount + MAX_CLMACROS + 18) * sizeof(char *)); |
059ec3d9 PH |
78 | |
79 | /* In all case, the list starts out with the path, any macros, and a changed | |
80 | config file. */ | |
81 | ||
82 | argv[n++] = exim_path; | |
83 | if (clmacro_count > 0) | |
84 | { | |
85 | memcpy(argv + n, clmacros, clmacro_count * sizeof(uschar *)); | |
86 | n += clmacro_count; | |
87 | } | |
88 | if (config_changed) | |
89 | { | |
90 | argv[n++] = US"-C"; | |
91 | argv[n++] = config_main_filename; | |
92 | } | |
93 | ||
94 | /* These values are added only for non-minimal cases. If debug_selector is | |
95 | precisely D_v, we have to assume this was started by a non-admin user, and | |
96 | we suppress the flag when requested. (This happens when passing on an SMTP | |
97 | connection, and after ETRN.) If there's more debugging going on, an admin user | |
98 | was involved, so we do pass it on. */ | |
99 | ||
100 | if (!minimal) | |
101 | { | |
102 | if (debug_selector == D_v) | |
103 | { | |
104 | if (!kill_v) argv[n++] = US"-v"; | |
105 | } | |
106 | else | |
107 | { | |
108 | if (debug_selector != 0) | |
109 | argv[n++] = string_sprintf("-d=0x%x", debug_selector); | |
110 | } | |
111 | if (dont_deliver) argv[n++] = US"-N"; | |
112 | if (queue_smtp) argv[n++] = US"-odqs"; | |
113 | if (synchronous_delivery) argv[n++] = US"-odi"; | |
114 | if (connection_max_messages >= 0) | |
115 | argv[n++] = string_sprintf("-oB%d", connection_max_messages); | |
e37f8a84 JH |
116 | if (*queue_name) |
117 | { | |
118 | argv[n++] = US"-MCG"; | |
119 | argv[n++] = queue_name; | |
120 | } | |
059ec3d9 PH |
121 | } |
122 | ||
123 | /* Now add in any others that are in the call. Remember which they were, | |
124 | for more helpful diagnosis on failure. */ | |
125 | ||
126 | if (acount > 0) | |
127 | { | |
128 | va_list ap; | |
129 | va_start(ap, acount); | |
130 | first_special = n; | |
131 | while (acount-- > 0) | |
132 | argv[n++] = va_arg(ap, uschar *); | |
133 | va_end(ap); | |
134 | } | |
135 | ||
136 | /* Terminate the list, and return it, if that is what is wanted. */ | |
137 | ||
138 | argv[n] = NULL; | |
139 | if (exec_type == CEE_RETURN_ARGV) | |
140 | { | |
141 | if (pcount != NULL) *pcount = n; | |
142 | return argv; | |
143 | } | |
144 | ||
145 | /* Otherwise, do the exec() here, and handle the consequences of an unexpected | |
146 | failure. We know that there will always be at least one extra option in the | |
147 | call when exec() is done here, so it can be used to add to the panic data. */ | |
148 | ||
55414b25 | 149 | DEBUG(D_exec) debug_print_argv(CUSS argv); |
059ec3d9 PH |
150 | exim_nullstd(); /* Make sure std{in,out,err} exist */ |
151 | execv(CS argv[0], (char *const *)argv); | |
152 | ||
153 | log_write(0, | |
154 | LOG_MAIN | ((exec_type == CEE_EXEC_EXIT)? LOG_PANIC : LOG_PANIC_DIE), | |
155 | "re-exec of exim (%s) with %s failed: %s", exim_path, argv[first_special], | |
156 | strerror(errno)); | |
157 | ||
158 | /* Get here if exec_type == CEE_EXEC_EXIT. | |
159 | Note: this must be _exit(), not exit(). */ | |
160 | ||
161 | _exit(EX_EXECFAILED); | |
162 | ||
163 | return NULL; /* To keep compilers happy */ | |
164 | } | |
165 | ||
166 | ||
167 | ||
168 | ||
169 | /************************************************* | |
170 | * Create a child Exim process * | |
171 | *************************************************/ | |
172 | ||
173 | /* This function is called when Exim wants to run a parallel instance of itself | |
174 | in order to inject a message via the standard input. The function creates a | |
175 | child process and runs Exim in it. It sets up a pipe to the standard input of | |
176 | the new process, and returns that to the caller via fdptr. The function returns | |
177 | the pid of the new process, or -1 if things go wrong. If debug_fd is | |
178 | non-negative, it is passed as stderr. | |
179 | ||
5977a0b3 PH |
180 | This interface is now a just wrapper for the more complicated function |
181 | child_open_exim2(), which has additional arguments. The wrapper must continue | |
182 | to exist, even if all calls from within Exim are changed, because it is | |
183 | documented for use from local_scan(). | |
184 | ||
059ec3d9 PH |
185 | Argument: fdptr pointer to int for the stdin fd |
186 | Returns: pid of the created process or -1 if anything has gone wrong | |
187 | */ | |
188 | ||
189 | pid_t | |
190 | child_open_exim(int *fdptr) | |
191 | { | |
5977a0b3 PH |
192 | return child_open_exim2(fdptr, US"<>", bounce_sender_authentication); |
193 | } | |
194 | ||
195 | ||
196 | /* This is a more complicated function for creating a child Exim process, with | |
197 | more arguments. | |
198 | ||
199 | Arguments: | |
200 | fdptr pointer to int for the stdin fd | |
201 | sender for a sender address (data for -f) | |
202 | sender_authentication authenticated sender address or NULL | |
203 | ||
204 | Returns: pid of the created process or -1 if anything has gone wrong | |
205 | */ | |
206 | ||
207 | pid_t | |
208 | child_open_exim2(int *fdptr, uschar *sender, uschar *sender_authentication) | |
209 | { | |
059ec3d9 PH |
210 | int pfd[2]; |
211 | int save_errno; | |
212 | pid_t pid; | |
213 | ||
214 | /* Create the pipe and fork the process. Ensure that SIGCHLD is set to | |
215 | SIG_DFL before forking, so that the child process can be waited for. We | |
216 | sometimes get here with it set otherwise. Save the old state for resetting | |
217 | on the wait. */ | |
218 | ||
219 | if (pipe(pfd) != 0) return (pid_t)(-1); | |
220 | oldsignal = signal(SIGCHLD, SIG_DFL); | |
221 | pid = fork(); | |
222 | ||
223 | /* Child process: make the reading end of the pipe into the standard input and | |
224 | close the writing end. If debugging, pass debug_fd as stderr. Then re-exec | |
4c04137d | 225 | Exim with appropriate options. In the test harness, use -odi unless queue_only |
75e0e026 PH |
226 | is set, so that the bounce is fully delivered before returning. Failure is |
227 | signalled with EX_EXECFAILED (specified by CEE_EXEC_EXIT), but this shouldn't | |
228 | occur. */ | |
059ec3d9 PH |
229 | |
230 | if (pid == 0) | |
231 | { | |
232 | force_fd(pfd[pipe_read], 0); | |
f1e894f3 | 233 | (void)close(pfd[pipe_write]); |
059ec3d9 | 234 | if (debug_fd > 0) force_fd(debug_fd, 2); |
75e0e026 PH |
235 | if (running_in_test_harness && !queue_only) |
236 | { | |
237 | if (sender_authentication != NULL) | |
238 | child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 9, | |
239 | US "-odi", US"-t", US"-oem", US"-oi", US"-f", sender, US"-oMas", | |
240 | sender_authentication, message_id_option); | |
241 | else | |
242 | child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 7, | |
243 | US "-odi", US"-t", US"-oem", US"-oi", US"-f", sender, | |
244 | message_id_option); | |
245 | /* Control does not return here. */ | |
246 | } | |
247 | else /* Not test harness */ | |
248 | { | |
249 | if (sender_authentication != NULL) | |
250 | child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 8, | |
251 | US"-t", US"-oem", US"-oi", US"-f", sender, US"-oMas", | |
252 | sender_authentication, message_id_option); | |
253 | else | |
254 | child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 6, | |
255 | US"-t", US"-oem", US"-oi", US"-f", sender, message_id_option); | |
256 | /* Control does not return here. */ | |
257 | } | |
059ec3d9 PH |
258 | } |
259 | ||
260 | /* Parent process. Save fork() errno and close the reading end of the stdin | |
261 | pipe. */ | |
262 | ||
263 | save_errno = errno; | |
f1e894f3 | 264 | (void)close(pfd[pipe_read]); |
059ec3d9 PH |
265 | |
266 | /* Fork succeeded */ | |
267 | ||
268 | if (pid > 0) | |
269 | { | |
270 | *fdptr = pfd[pipe_write]; /* return writing end of stdin pipe */ | |
271 | return pid; /* and pid of new process */ | |
272 | } | |
273 | ||
274 | /* Fork failed */ | |
275 | ||
f1e894f3 | 276 | (void)close(pfd[pipe_write]); |
059ec3d9 PH |
277 | errno = save_errno; |
278 | return (pid_t)(-1); | |
279 | } | |
75e0e026 | 280 | #endif /* STAND_ALONE */ |
059ec3d9 PH |
281 | |
282 | ||
283 | ||
284 | /************************************************* | |
285 | * Create a non-Exim child process * | |
286 | *************************************************/ | |
287 | ||
288 | /* This function creates a child process and runs the given command in it. It | |
289 | sets up pipes to the standard input and output of the new process, and returns | |
290 | them to the caller. The standard error is cloned to the output. If there are | |
291 | any file descriptors "in the way" in the new process, they are closed. A new | |
292 | umask is supplied for the process, and an optional new uid and gid are also | |
293 | available. These are used by the queryprogram router to set an unprivileged id. | |
b668c215 PH |
294 | SIGUSR1 is always disabled in the new process, as it is not going to be running |
295 | Exim (the function child_open_exim() is provided for that). This function | |
296 | returns the pid of the new process, or -1 if things go wrong. | |
059ec3d9 PH |
297 | |
298 | Arguments: | |
299 | argv the argv for exec in the new process | |
300 | envp the envp for exec in the new process | |
301 | newumask umask to set in the new process | |
302 | newuid point to uid for the new process or NULL for no change | |
303 | newgid point to gid for the new process or NULL for no change | |
304 | infdptr pointer to int into which the fd of the stdin of the new process | |
305 | is placed | |
306 | outfdptr pointer to int into which the fd of the stdout/stderr of the new | |
307 | process is placed | |
308 | wd if not NULL, a path to be handed to chdir() in the new process | |
309 | make_leader if TRUE, make the new process a process group leader | |
8e669ac1 | 310 | |
059ec3d9 PH |
311 | Returns: the pid of the created process or -1 if anything has gone wrong |
312 | */ | |
313 | ||
314 | pid_t | |
55414b25 JH |
315 | child_open_uid(const uschar **argv, const uschar **envp, int newumask, |
316 | uid_t *newuid, gid_t *newgid, int *infdptr, int *outfdptr, uschar *wd, | |
317 | BOOL make_leader) | |
059ec3d9 PH |
318 | { |
319 | int save_errno; | |
320 | int inpfd[2], outpfd[2]; | |
321 | pid_t pid; | |
322 | ||
323 | /* Create the pipes. */ | |
324 | ||
325 | if (pipe(inpfd) != 0) return (pid_t)(-1); | |
326 | if (pipe(outpfd) != 0) | |
327 | { | |
f1e894f3 PH |
328 | (void)close(inpfd[pipe_read]); |
329 | (void)close(inpfd[pipe_write]); | |
059ec3d9 PH |
330 | return (pid_t)(-1); |
331 | } | |
332 | ||
333 | /* Fork the process. Ensure that SIGCHLD is set to SIG_DFL before forking, so | |
334 | that the child process can be waited for. We sometimes get here with it set | |
335 | otherwise. Save the old state for resetting on the wait. */ | |
336 | ||
337 | oldsignal = signal(SIGCHLD, SIG_DFL); | |
338 | pid = fork(); | |
339 | ||
59e82a2a PH |
340 | /* Handle the child process. First, set the required environment. We must do |
341 | this before messing with the pipes, in order to be able to write debugging | |
342 | output when things go wrong. */ | |
059ec3d9 PH |
343 | |
344 | if (pid == 0) | |
345 | { | |
59e82a2a | 346 | signal(SIGUSR1, SIG_IGN); |
605021fc | 347 | signal(SIGPIPE, SIG_DFL); |
59e82a2a PH |
348 | |
349 | if (newgid != NULL && setgid(*newgid) < 0) | |
350 | { | |
351 | DEBUG(D_any) debug_printf("failed to set gid=%ld in subprocess: %s\n", | |
352 | (long int)(*newgid), strerror(errno)); | |
353 | goto CHILD_FAILED; | |
354 | } | |
355 | ||
356 | if (newuid != NULL && setuid(*newuid) < 0) | |
357 | { | |
358 | DEBUG(D_any) debug_printf("failed to set uid=%ld in subprocess: %s\n", | |
359 | (long int)(*newuid), strerror(errno)); | |
360 | goto CHILD_FAILED; | |
361 | } | |
362 | ||
363 | (void)umask(newumask); | |
364 | ||
365 | if (wd != NULL && Uchdir(wd) < 0) | |
366 | { | |
367 | DEBUG(D_any) debug_printf("failed to chdir to %s: %s\n", wd, | |
368 | strerror(errno)); | |
369 | goto CHILD_FAILED; | |
370 | } | |
371 | ||
372 | /* Becomes a process group leader if requested, and then organize the pipes. | |
373 | Any unexpected failure is signalled with EX_EXECFAILED; these are all "should | |
374 | never occur" failures, except for exec failing because the command doesn't | |
375 | exist. */ | |
376 | ||
377 | if (make_leader && setpgid(0,0) < 0) | |
378 | { | |
379 | DEBUG(D_any) debug_printf("failed to set group leader in subprocess: %s\n", | |
380 | strerror(errno)); | |
381 | goto CHILD_FAILED; | |
382 | } | |
059ec3d9 | 383 | |
f1e894f3 | 384 | (void)close(inpfd[pipe_write]); |
059ec3d9 PH |
385 | force_fd(inpfd[pipe_read], 0); |
386 | ||
f1e894f3 | 387 | (void)close(outpfd[pipe_read]); |
059ec3d9 PH |
388 | force_fd(outpfd[pipe_write], 1); |
389 | ||
f1e894f3 PH |
390 | (void)close(2); |
391 | (void)dup2(1, 2); | |
059ec3d9 | 392 | |
059ec3d9 PH |
393 | /* Now do the exec */ |
394 | ||
395 | if (envp == NULL) execv(CS argv[0], (char *const *)argv); | |
55414b25 | 396 | else execve(CS argv[0], (char *const *)argv, (char *const *)envp); |
059ec3d9 PH |
397 | |
398 | /* Failed to execv. Signal this failure using EX_EXECFAILED. We are | |
399 | losing the actual errno we got back, because there is no way to return | |
59e82a2a | 400 | this information. */ |
059ec3d9 PH |
401 | |
402 | CHILD_FAILED: | |
403 | _exit(EX_EXECFAILED); /* Note: must be _exit(), NOT exit() */ | |
404 | } | |
405 | ||
406 | /* Parent process. Save any fork failure code, and close the reading end of the | |
407 | stdin pipe, and the writing end of the stdout pipe. */ | |
408 | ||
409 | save_errno = errno; | |
f1e894f3 PH |
410 | (void)close(inpfd[pipe_read]); |
411 | (void)close(outpfd[pipe_write]); | |
059ec3d9 PH |
412 | |
413 | /* Fork succeeded; return the input/output pipes and the pid */ | |
414 | ||
415 | if (pid > 0) | |
416 | { | |
417 | *infdptr = inpfd[pipe_write]; | |
418 | *outfdptr = outpfd[pipe_read]; | |
419 | return pid; | |
420 | } | |
421 | ||
422 | /* Fork failed; reset fork errno before returning */ | |
423 | ||
f1e894f3 PH |
424 | (void)close(inpfd[pipe_write]); |
425 | (void)close(outpfd[pipe_read]); | |
059ec3d9 PH |
426 | errno = save_errno; |
427 | return (pid_t)(-1); | |
428 | } | |
429 | ||
430 | ||
431 | ||
432 | ||
433 | /************************************************* | |
434 | * Create child process without uid change * | |
435 | *************************************************/ | |
436 | ||
437 | /* This function is a wrapper for child_open_uid() that doesn't have the uid, | |
b668c215 PH |
438 | gid and working directory changing arguments. The function is provided so as to |
439 | have a clean interface for use from local_scan(), but also saves writing NULL | |
440 | arguments several calls that would otherwise use child_open_uid(). | |
059ec3d9 PH |
441 | |
442 | Arguments: | |
443 | argv the argv for exec in the new process | |
444 | envp the envp for exec in the new process | |
445 | newumask umask to set in the new process | |
446 | infdptr pointer to int into which the fd of the stdin of the new process | |
447 | is placed | |
448 | outfdptr pointer to int into which the fd of the stdout/stderr of the new | |
449 | process is placed | |
450 | make_leader if TRUE, make the new process a process group leader | |
451 | ||
452 | Returns: the pid of the created process or -1 if anything has gone wrong | |
453 | */ | |
454 | ||
455 | pid_t | |
456 | child_open(uschar **argv, uschar **envp, int newumask, int *infdptr, | |
457 | int *outfdptr, BOOL make_leader) | |
458 | { | |
55414b25 JH |
459 | return child_open_uid(CUSS argv, CUSS envp, newumask, NULL, NULL, |
460 | infdptr, outfdptr, NULL, make_leader); | |
059ec3d9 PH |
461 | } |
462 | ||
463 | ||
464 | ||
465 | ||
466 | /************************************************* | |
467 | * Close down child process * | |
468 | *************************************************/ | |
469 | ||
470 | /* Wait for the given process to finish, with optional timeout. | |
471 | ||
472 | Arguments | |
473 | pid: the pid to wait for | |
474 | timeout: maximum time to wait; 0 means for as long as it takes | |
475 | ||
476 | Returns: >= 0 process terminated by exiting; value is process | |
477 | ending status; if an execve() failed, the value | |
478 | is typically 127 (defined as EX_EXECFAILED) | |
479 | < 0 & > -256 process was terminated by a signal; value is the | |
480 | negation of the signal number | |
481 | -256 timed out | |
482 | -257 other error in wait(); errno still set | |
483 | */ | |
484 | ||
485 | int | |
486 | child_close(pid_t pid, int timeout) | |
487 | { | |
488 | int yield; | |
489 | ||
490 | if (timeout > 0) | |
491 | { | |
492 | sigalrm_seen = FALSE; | |
493 | alarm(timeout); | |
494 | } | |
495 | ||
496 | for(;;) | |
497 | { | |
498 | int status; | |
499 | pid_t rc = waitpid(pid, &status, 0); | |
500 | if (rc == pid) | |
501 | { | |
502 | int lowbyte = status & 255; | |
503 | if (lowbyte == 0) yield = (status >> 8) & 255; | |
504 | else yield = -lowbyte; | |
505 | break; | |
506 | } | |
507 | if (rc < 0) | |
508 | { | |
509 | yield = (errno == EINTR && sigalrm_seen)? -256 : -257; | |
510 | break; | |
511 | } | |
512 | } | |
513 | ||
514 | if (timeout > 0) alarm(0); | |
515 | ||
516 | signal(SIGCHLD, oldsignal); /* restore */ | |
517 | return yield; | |
518 | } | |
519 | ||
520 | /* End of child.c */ |