1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 /* Copyright (c) University of Cambridge 1995 - 2015 */
6 /* See the file NOTICE for conditions of use and distribution. */
11 static void (*oldsignal)(int);
14 /*************************************************
15 * Ensure an fd has a given value *
16 *************************************************/
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.
30 force_fd(int oldfd, int newfd)
32 if (oldfd == newfd) return;
34 (void)dup2(oldfd, newfd);
40 /*************************************************
41 * Build argv list and optionally re-exec Exim *
42 *************************************************/
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.
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
61 minimal TRUE if only minimal argv is required
62 acount number of additional arguments
63 ... further values to add to argv
65 Returns: if CEE_RETURN_ARGV is given, returns a pointer to argv;
66 otherwise, does not return
70 child_exec_exim(int exec_type, BOOL kill_v, int *pcount, BOOL minimal,
73 int first_special = -1;
75 int extra = pcount ? *pcount : 0;
78 argv = store_get((extra + acount + MAX_CLMACROS + 21) * sizeof(char *), FALSE);
80 /* In all case, the list starts out with the path, any macros, and a changed
83 argv[n++] = exim_path;
84 if (clmacro_count > 0)
86 memcpy(argv + n, clmacros, clmacro_count * sizeof(uschar *));
92 argv[n++] = config_main_filename;
95 /* These values are added only for non-minimal cases. If debug_selector is
96 precisely D_v, we have to assume this was started by a non-admin user, and
97 we suppress the flag when requested. (This happens when passing on an SMTP
98 connection, and after ETRN.) If there's more debugging going on, an admin user
99 was involved, so we do pass it on. */
103 if (debug_selector == D_v)
105 if (!kill_v) argv[n++] = US"-v";
109 if (debug_selector != 0)
110 argv[n++] = string_sprintf("-d=0x%x", debug_selector);
112 if (!f.testsuite_delays) argv[n++] = US"-odd";
113 if (f.dont_deliver) argv[n++] = US"-N";
114 if (f.queue_smtp) argv[n++] = US"-odqs";
115 if (f.synchronous_delivery) argv[n++] = US"-odi";
116 if (connection_max_messages >= 0)
117 argv[n++] = string_sprintf("-oB%d", connection_max_messages);
120 argv[n++] = US"-MCG";
121 argv[n++] = queue_name;
125 /* Now add in any others that are in the call. Remember which they were,
126 for more helpful diagnosis on failure. */
131 va_start(ap, acount);
134 argv[n++] = va_arg(ap, uschar *);
138 /* Terminate the list, and return it, if that is what is wanted. */
141 if (exec_type == CEE_RETURN_ARGV)
143 if (pcount != NULL) *pcount = n;
147 /* Otherwise, do the exec() here, and handle the consequences of an unexpected
148 failure. We know that there will always be at least one extra option in the
149 call when exec() is done here, so it can be used to add to the panic data. */
151 DEBUG(D_exec) debug_print_argv(CUSS argv);
152 exim_nullstd(); /* Make sure std{in,out,err} exist */
153 execv(CS argv[0], (char *const *)argv);
156 LOG_MAIN | ((exec_type == CEE_EXEC_EXIT)? LOG_PANIC : LOG_PANIC_DIE),
157 "re-exec of exim (%s) with %s failed: %s", exim_path, argv[first_special],
160 /* Get here if exec_type == CEE_EXEC_EXIT.
161 Note: this must be _exit(), not exit(). */
163 _exit(EX_EXECFAILED);
165 return NULL; /* To keep compilers happy */
171 /*************************************************
172 * Create a child Exim process *
173 *************************************************/
175 /* This function is called when Exim wants to run a parallel instance of itself
176 in order to inject a message via the standard input. The function creates a
177 child process and runs Exim in it. It sets up a pipe to the standard input of
178 the new process, and returns that to the caller via fdptr. The function returns
179 the pid of the new process, or -1 if things go wrong. If debug_fd is
180 non-negative, it is passed as stderr.
182 This interface is now a just wrapper for the more complicated function
183 child_open_exim2(), which has additional arguments. The wrapper must continue
184 to exist, even if all calls from within Exim are changed, because it is
185 documented for use from local_scan().
187 Argument: fdptr pointer to int for the stdin fd
188 purpose of the child process, for debug
189 Returns: pid of the created process or -1 if anything has gone wrong
193 child_open_exim_function(int * fdptr, const uschar * purpose)
195 return child_open_exim2_function(fdptr, US"<>", bounce_sender_authentication,
200 /* This is a more complicated function for creating a child Exim process, with
204 fdptr pointer to int for the stdin fd
205 sender for a sender address (data for -f)
206 sender_authentication authenticated sender address or NULL
207 purpose of the child process, for debug
209 Returns: pid of the created process or -1 if anything has gone wrong
213 child_open_exim2_function(int * fdptr, uschar * sender,
214 uschar * sender_authentication, const uschar * purpose)
220 /* Create the pipe and fork the process. Ensure that SIGCHLD is set to
221 SIG_DFL before forking, so that the child process can be waited for. We
222 sometimes get here with it set otherwise. Save the old state for resetting
225 if (pipe(pfd) != 0) return (pid_t)(-1);
226 oldsignal = signal(SIGCHLD, SIG_DFL);
227 pid = exim_fork(purpose);
229 /* Child process: make the reading end of the pipe into the standard input and
230 close the writing end. If debugging, pass debug_fd as stderr. Then re-exec
231 Exim with appropriate options. In the test harness, use -odi unless queue_only
232 is set, so that the bounce is fully delivered before returning. Failure is
233 signalled with EX_EXECFAILED (specified by CEE_EXEC_EXIT), but this shouldn't
238 force_fd(pfd[pipe_read], 0);
239 (void)close(pfd[pipe_write]);
240 if (debug_fd > 0) force_fd(debug_fd, 2);
241 if (f.running_in_test_harness && !queue_only)
243 if (sender_authentication)
244 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 9,
245 US "-odi", US"-t", US"-oem", US"-oi", US"-f", sender, US"-oMas",
246 sender_authentication, message_id_option);
248 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 7,
249 US "-odi", US"-t", US"-oem", US"-oi", US"-f", sender,
251 /* Control does not return here. */
253 else /* Not test harness */
255 if (sender_authentication)
256 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 8,
257 US"-t", US"-oem", US"-oi", US"-f", sender, US"-oMas",
258 sender_authentication, message_id_option);
260 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 6,
261 US"-t", US"-oem", US"-oi", US"-f", sender, message_id_option);
262 /* Control does not return here. */
266 /* Parent process. Save fork() errno and close the reading end of the stdin
270 (void)close(pfd[pipe_read]);
276 *fdptr = pfd[pipe_write]; /* return writing end of stdin pipe */
277 return pid; /* and pid of new process */
282 (void)close(pfd[pipe_write]);
286 #endif /* STAND_ALONE */
290 /*************************************************
291 * Create a non-Exim child process *
292 *************************************************/
294 /* This function creates a child process and runs the given command in it. It
295 sets up pipes to the standard input and output of the new process, and returns
296 them to the caller. The standard error is cloned to the output. If there are
297 any file descriptors "in the way" in the new process, they are closed. A new
298 umask is supplied for the process, and an optional new uid and gid are also
299 available. These are used by the queryprogram router to set an unprivileged id.
300 SIGUSR1 is always disabled in the new process, as it is not going to be running
301 Exim (the function child_open_exim() is provided for that). This function
302 returns the pid of the new process, or -1 if things go wrong.
305 argv the argv for exec in the new process
306 envp the envp for exec in the new process
307 newumask umask to set in the new process
308 newuid point to uid for the new process or NULL for no change
309 newgid point to gid for the new process or NULL for no change
310 infdptr pointer to int into which the fd of the stdin of the new process
312 outfdptr pointer to int into which the fd of the stdout/stderr of the new
314 wd if not NULL, a path to be handed to chdir() in the new process
315 make_leader if TRUE, make the new process a process group leader
316 purpose for debug: reason for running the task
318 Returns: the pid of the created process or -1 if anything has gone wrong
322 child_open_uid(const uschar **argv, const uschar **envp, int newumask,
323 uid_t *newuid, gid_t *newgid, int *infdptr, int *outfdptr, uschar *wd,
324 BOOL make_leader, const uschar * purpose)
327 int inpfd[2], outpfd[2];
330 /* Create the pipes. */
332 if (pipe(inpfd) != 0) return (pid_t)(-1);
333 if (pipe(outpfd) != 0)
335 (void)close(inpfd[pipe_read]);
336 (void)close(inpfd[pipe_write]);
340 /* Fork the process. Ensure that SIGCHLD is set to SIG_DFL before forking, so
341 that the child process can be waited for. We sometimes get here with it set
342 otherwise. Save the old state for resetting on the wait. */
344 oldsignal = signal(SIGCHLD, SIG_DFL);
345 pid = exim_fork(purpose);
347 /* Handle the child process. First, set the required environment. We must do
348 this before messing with the pipes, in order to be able to write debugging
349 output when things go wrong. */
353 signal(SIGUSR1, SIG_IGN);
354 signal(SIGPIPE, SIG_DFL);
356 if (newgid && setgid(*newgid) < 0)
358 DEBUG(D_any) debug_printf("failed to set gid=%ld in subprocess: %s\n",
359 (long int)(*newgid), strerror(errno));
363 if (newuid && setuid(*newuid) < 0)
365 DEBUG(D_any) debug_printf("failed to set uid=%ld in subprocess: %s\n",
366 (long int)(*newuid), strerror(errno));
370 (void)umask(newumask);
372 if (wd && Uchdir(wd) < 0)
374 DEBUG(D_any) debug_printf("failed to chdir to %s: %s\n", wd,
379 /* Becomes a process group leader if requested, and then organize the pipes.
380 Any unexpected failure is signalled with EX_EXECFAILED; these are all "should
381 never occur" failures, except for exec failing because the command doesn't
384 if (make_leader && setpgid(0,0) < 0)
386 DEBUG(D_any) debug_printf("failed to set group leader in subprocess: %s\n",
391 (void)close(inpfd[pipe_write]);
392 force_fd(inpfd[pipe_read], 0);
394 (void)close(outpfd[pipe_read]);
395 force_fd(outpfd[pipe_write], 1);
400 /* Now do the exec */
402 if (envp) execve(CS argv[0], (char *const *)argv, (char *const *)envp);
403 else execv(CS argv[0], (char *const *)argv);
405 /* Failed to execv. Signal this failure using EX_EXECFAILED. We are
406 losing the actual errno we got back, because there is no way to return
410 _exit(EX_EXECFAILED); /* Note: must be _exit(), NOT exit() */
413 /* Parent process. Save any fork failure code, and close the reading end of the
414 stdin pipe, and the writing end of the stdout pipe. */
417 (void)close(inpfd[pipe_read]);
418 (void)close(outpfd[pipe_write]);
420 /* Fork succeeded; return the input/output pipes and the pid */
424 *infdptr = inpfd[pipe_write];
425 *outfdptr = outpfd[pipe_read];
429 /* Fork failed; reset fork errno before returning */
431 (void)close(inpfd[pipe_write]);
432 (void)close(outpfd[pipe_read]);
440 /*************************************************
441 * Create child process without uid change *
442 *************************************************/
444 /* This function is a wrapper for child_open_uid() that doesn't have the uid,
445 gid and working directory changing arguments. The function is provided so as to
446 have a clean interface for use from local_scan(), but also saves writing NULL
447 arguments several calls that would otherwise use child_open_uid().
450 argv the argv for exec in the new process
451 envp the envp for exec in the new process
452 newumask umask to set in the new process
453 infdptr pointer to int into which the fd of the stdin of the new process
455 outfdptr pointer to int into which the fd of the stdout/stderr of the new
457 make_leader if TRUE, make the new process a process group leader
458 purpose for debug: reason for running the task
460 Returns: the pid of the created process or -1 if anything has gone wrong
464 child_open_function(uschar **argv, uschar **envp, int newumask, int *infdptr,
465 int *outfdptr, BOOL make_leader, const uschar * purpose)
467 return child_open_uid(CUSS argv, CUSS envp, newumask, NULL, NULL,
468 infdptr, outfdptr, NULL, make_leader, purpose);
474 /*************************************************
475 * Close down child process *
476 *************************************************/
478 /* Wait for the given process to finish, with optional timeout.
481 pid: the pid to wait for
482 timeout: maximum time to wait; 0 means for as long as it takes
484 Returns: >= 0 process terminated by exiting; value is process
485 ending status; if an execve() failed, the value
486 is typically 127 (defined as EX_EXECFAILED)
487 < 0 & > -256 process was terminated by a signal; value is the
488 negation of the signal number
490 -257 other error in wait(); errno still set
494 child_close(pid_t pid, int timeout)
500 sigalrm_seen = FALSE;
507 pid_t rc = waitpid(pid, &status, 0);
510 int lowbyte = status & 255;
511 yield = lowbyte == 0 ? (status >> 8) & 255 : -lowbyte;
516 /* This "shouldn't happen" test does happen on MacOS: for some reason
517 I do not understand we seems to get an alarm signal despite not having
518 an active alarm set. There seems to be only one, so just go round again. */
520 if (errno == EINTR && sigalrm_seen && timeout <= 0) continue;
522 yield = (errno == EINTR && sigalrm_seen) ? -256 : -257;
527 if (timeout > 0) ALARM_CLR(0);
529 signal(SIGCHLD, oldsignal); /* restore */