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 + 19) * 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 Returns: pid of the created process or -1 if anything has gone wrong
192 child_open_exim(int *fdptr)
194 return child_open_exim2(fdptr, US"<>", bounce_sender_authentication);
198 /* This is a more complicated function for creating a child Exim process, with
202 fdptr pointer to int for the stdin fd
203 sender for a sender address (data for -f)
204 sender_authentication authenticated sender address or NULL
206 Returns: pid of the created process or -1 if anything has gone wrong
210 child_open_exim2(int *fdptr, uschar *sender, uschar *sender_authentication)
216 /* Create the pipe and fork the process. Ensure that SIGCHLD is set to
217 SIG_DFL before forking, so that the child process can be waited for. We
218 sometimes get here with it set otherwise. Save the old state for resetting
221 if (pipe(pfd) != 0) return (pid_t)(-1);
222 oldsignal = signal(SIGCHLD, SIG_DFL);
225 /* Child process: make the reading end of the pipe into the standard input and
226 close the writing end. If debugging, pass debug_fd as stderr. Then re-exec
227 Exim with appropriate options. In the test harness, use -odi unless queue_only
228 is set, so that the bounce is fully delivered before returning. Failure is
229 signalled with EX_EXECFAILED (specified by CEE_EXEC_EXIT), but this shouldn't
234 force_fd(pfd[pipe_read], 0);
235 (void)close(pfd[pipe_write]);
236 if (debug_fd > 0) force_fd(debug_fd, 2);
237 if (f.running_in_test_harness && !queue_only)
239 if (sender_authentication != NULL)
240 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 9,
241 US "-odi", US"-t", US"-oem", US"-oi", US"-f", sender, US"-oMas",
242 sender_authentication, message_id_option);
244 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 7,
245 US "-odi", US"-t", US"-oem", US"-oi", US"-f", sender,
247 /* Control does not return here. */
249 else /* Not test harness */
251 if (sender_authentication != NULL)
252 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 8,
253 US"-t", US"-oem", US"-oi", US"-f", sender, US"-oMas",
254 sender_authentication, message_id_option);
256 child_exec_exim(CEE_EXEC_EXIT, FALSE, NULL, FALSE, 6,
257 US"-t", US"-oem", US"-oi", US"-f", sender, message_id_option);
258 /* Control does not return here. */
262 /* Parent process. Save fork() errno and close the reading end of the stdin
266 (void)close(pfd[pipe_read]);
272 *fdptr = pfd[pipe_write]; /* return writing end of stdin pipe */
273 return pid; /* and pid of new process */
278 (void)close(pfd[pipe_write]);
282 #endif /* STAND_ALONE */
286 /*************************************************
287 * Create a non-Exim child process *
288 *************************************************/
290 /* This function creates a child process and runs the given command in it. It
291 sets up pipes to the standard input and output of the new process, and returns
292 them to the caller. The standard error is cloned to the output. If there are
293 any file descriptors "in the way" in the new process, they are closed. A new
294 umask is supplied for the process, and an optional new uid and gid are also
295 available. These are used by the queryprogram router to set an unprivileged id.
296 SIGUSR1 is always disabled in the new process, as it is not going to be running
297 Exim (the function child_open_exim() is provided for that). This function
298 returns the pid of the new process, or -1 if things go wrong.
301 argv the argv for exec in the new process
302 envp the envp for exec in the new process
303 newumask umask to set in the new process
304 newuid point to uid for the new process or NULL for no change
305 newgid point to gid for the new process or NULL for no change
306 infdptr pointer to int into which the fd of the stdin of the new process
308 outfdptr pointer to int into which the fd of the stdout/stderr of the new
310 wd if not NULL, a path to be handed to chdir() in the new process
311 make_leader if TRUE, make the new process a process group leader
313 Returns: the pid of the created process or -1 if anything has gone wrong
317 child_open_uid(const uschar **argv, const uschar **envp, int newumask,
318 uid_t *newuid, gid_t *newgid, int *infdptr, int *outfdptr, uschar *wd,
322 int inpfd[2], outpfd[2];
325 /* Create the pipes. */
327 if (pipe(inpfd) != 0) return (pid_t)(-1);
328 if (pipe(outpfd) != 0)
330 (void)close(inpfd[pipe_read]);
331 (void)close(inpfd[pipe_write]);
335 /* Fork the process. Ensure that SIGCHLD is set to SIG_DFL before forking, so
336 that the child process can be waited for. We sometimes get here with it set
337 otherwise. Save the old state for resetting on the wait. */
339 oldsignal = signal(SIGCHLD, SIG_DFL);
342 /* Handle the child process. First, set the required environment. We must do
343 this before messing with the pipes, in order to be able to write debugging
344 output when things go wrong. */
348 signal(SIGUSR1, SIG_IGN);
349 signal(SIGPIPE, SIG_DFL);
351 if (newgid != NULL && setgid(*newgid) < 0)
353 DEBUG(D_any) debug_printf("failed to set gid=%ld in subprocess: %s\n",
354 (long int)(*newgid), strerror(errno));
358 if (newuid != NULL && setuid(*newuid) < 0)
360 DEBUG(D_any) debug_printf("failed to set uid=%ld in subprocess: %s\n",
361 (long int)(*newuid), strerror(errno));
365 (void)umask(newumask);
367 if (wd != NULL && Uchdir(wd) < 0)
369 DEBUG(D_any) debug_printf("failed to chdir to %s: %s\n", wd,
374 /* Becomes a process group leader if requested, and then organize the pipes.
375 Any unexpected failure is signalled with EX_EXECFAILED; these are all "should
376 never occur" failures, except for exec failing because the command doesn't
379 if (make_leader && setpgid(0,0) < 0)
381 DEBUG(D_any) debug_printf("failed to set group leader in subprocess: %s\n",
386 (void)close(inpfd[pipe_write]);
387 force_fd(inpfd[pipe_read], 0);
389 (void)close(outpfd[pipe_read]);
390 force_fd(outpfd[pipe_write], 1);
395 /* Now do the exec */
397 if (envp == NULL) execv(CS argv[0], (char *const *)argv);
398 else execve(CS argv[0], (char *const *)argv, (char *const *)envp);
400 /* Failed to execv. Signal this failure using EX_EXECFAILED. We are
401 losing the actual errno we got back, because there is no way to return
405 _exit(EX_EXECFAILED); /* Note: must be _exit(), NOT exit() */
408 /* Parent process. Save any fork failure code, and close the reading end of the
409 stdin pipe, and the writing end of the stdout pipe. */
412 (void)close(inpfd[pipe_read]);
413 (void)close(outpfd[pipe_write]);
415 /* Fork succeeded; return the input/output pipes and the pid */
419 *infdptr = inpfd[pipe_write];
420 *outfdptr = outpfd[pipe_read];
424 /* Fork failed; reset fork errno before returning */
426 (void)close(inpfd[pipe_write]);
427 (void)close(outpfd[pipe_read]);
435 /*************************************************
436 * Create child process without uid change *
437 *************************************************/
439 /* This function is a wrapper for child_open_uid() that doesn't have the uid,
440 gid and working directory changing arguments. The function is provided so as to
441 have a clean interface for use from local_scan(), but also saves writing NULL
442 arguments several calls that would otherwise use child_open_uid().
445 argv the argv for exec in the new process
446 envp the envp for exec in the new process
447 newumask umask to set in the new process
448 infdptr pointer to int into which the fd of the stdin of the new process
450 outfdptr pointer to int into which the fd of the stdout/stderr of the new
452 make_leader if TRUE, make the new process a process group leader
454 Returns: the pid of the created process or -1 if anything has gone wrong
458 child_open(uschar **argv, uschar **envp, int newumask, int *infdptr,
459 int *outfdptr, BOOL make_leader)
461 return child_open_uid(CUSS argv, CUSS envp, newumask, NULL, NULL,
462 infdptr, outfdptr, NULL, make_leader);
468 /*************************************************
469 * Close down child process *
470 *************************************************/
472 /* Wait for the given process to finish, with optional timeout.
475 pid: the pid to wait for
476 timeout: maximum time to wait; 0 means for as long as it takes
478 Returns: >= 0 process terminated by exiting; value is process
479 ending status; if an execve() failed, the value
480 is typically 127 (defined as EX_EXECFAILED)
481 < 0 & > -256 process was terminated by a signal; value is the
482 negation of the signal number
484 -257 other error in wait(); errno still set
488 child_close(pid_t pid, int timeout)
494 sigalrm_seen = FALSE;
501 pid_t rc = waitpid(pid, &status, 0);
504 int lowbyte = status & 255;
505 yield = lowbyte == 0 ? (status >> 8) & 255 : -lowbyte;
510 /* This "shouldn't happen" test does happen on MacOS: for some reason
511 I do not understand we seems to get an alarm signal despite not having
512 an active alarm set. There seems to be only one, so just go round again. */
514 if (errno == EINTR && sigalrm_seen && timeout <= 0) continue;
516 yield = (errno == EINTR && sigalrm_seen) ? -256 : -257;
521 if (timeout > 0) ALARM_CLR(0);
523 signal(SIGCHLD, oldsignal); /* restore */