1 /*
2  * Copyright (c) 2010 - 2016 Reyk Floeter <reyk@openbsd.org>
3  * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org>
4  *
5  * Permission to use, copy, modify, and distribute this software for any
6  * purpose with or without fee is hereby granted, provided that the above
7  * copyright notice and this permission notice appear in all copies.
8  *
9  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16  */
17 
18 #include <sys/types.h>
19 #include <sys/queue.h>
20 #include <sys/socket.h>
21 #include <sys/wait.h>
22 
23 #include <fcntl.h>
24 #include <stdio.h>
25 #include <stdlib.h>
26 #include <unistd.h>
27 #include <string.h>
28 #include <errno.h>
29 #include <signal.h>
30 #include <pwd.h>
31 #include <event.h>
32 #include <imsg.h>
33 
34 #include "proc.h"
35 
36 void	 proc_exec(struct privsep *, struct privsep_proc *, unsigned int,
37 	    int, char **);
38 void	 proc_setup(struct privsep *, struct privsep_proc *, unsigned int);
39 void	 proc_open(struct privsep *, int, int);
40 void	 proc_accept(struct privsep *, int, enum privsep_procid,
41 	    unsigned int);
42 void	 proc_close(struct privsep *);
43 int	 proc_ispeer(struct privsep_proc *, unsigned int, enum privsep_procid);
44 void	 proc_shutdown(struct privsep_proc *);
45 void	 proc_sig_handler(int, short, void *);
46 int	 proc_dispatch_null(int, struct privsep_proc *, struct imsg *);
47 
48 enum privsep_procid privsep_process;
49 
50 int
51 proc_ispeer(struct privsep_proc *procs, unsigned int nproc,
52     enum privsep_procid type)
53 {
54 	unsigned int i;
55 
56 	for (i = 0; i < nproc; i++)
57 		if (procs[i].p_id == type)
58 			return (1);
59 
60 	return (0);
61 }
62 
63 enum privsep_procid
64 proc_getid(struct privsep_proc *procs, unsigned int nproc,
65     const char *proc_name)
66 {
67 	struct privsep_proc *p;
68 	unsigned int proc;
69 
70 	for (proc = 0; proc < nproc; proc++) {
71 		p = &procs[proc];
72 		if (strcmp(p->p_title, proc_name))
73 			continue;
74 
75 		return (p->p_id);
76 	}
77 
78 	return (PROC_MAX);
79 }
80 
81 void
82 proc_exec(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc,
83     int argc, char **argv)
84 {
85 	unsigned int proc, nargc, i, proc_i;
86 	char **nargv;
87 	struct privsep_proc *p;
88 	char num[32];
89 	int fd;
90 
91 	/* Prepare the new process argv. */
92 	nargv = calloc(argc + 5, sizeof(char *));
93 	if (nargv == NULL)
94 		fatal("%s: calloc", __func__);
95 
96 	/* Copy call argument first. */
97 	nargc = 0;
98 	nargv[nargc++] = argv[0];
99 
100 	/* Set process name argument and save the position. */
101 	nargv[nargc] = strdup("-P");
102 	if (nargv[nargc] == NULL)
103 		fatal("%s: strdup", __func__);
104 	nargc++;
105 	proc_i = nargc;
106 	nargc++;
107 
108 	/* Point process instance arg to stack and copy the original args. */
109 	nargv[nargc] = strdup("-I");
110 	if (nargv[nargc] == NULL)
111 		fatal("%s: strdup", __func__);
112 	nargc++;
113 	nargv[nargc++] = num;
114 	for (i = 1; i < (unsigned int) argc; i++)
115 		nargv[nargc++] = argv[i];
116 
117 	nargv[nargc] = NULL;
118 
119 	for (proc = 0; proc < nproc; proc++) {
120 		p = &procs[proc];
121 
122 		/* Update args with process title. */
123 		nargv[proc_i] = (char *)(uintptr_t)p->p_title;
124 
125 		/* Fire children processes. */
126 		for (i = 0; i < ps->ps_instances[p->p_id]; i++) {
127 			/* Update the process instance number. */
128 			snprintf(num, sizeof(num), "%u", i);
129 
130 			fd = ps->ps_pipes[p->p_id][i].pp_pipes[PROC_GOTWEBD][0];
131 			ps->ps_pipes[p->p_id][i].pp_pipes[PROC_GOTWEBD][0] = -1;
132 
133 			switch (fork()) {
134 			case -1:
135 				fatal("%s: fork", __func__);
136 				break;
137 			case 0:
138 				/* First create a new session */
139 				if (setsid() == -1)
140 					fatal("setsid");
141 
142 				/* Prepare parent socket. */
143 				if (fd != PROC_GOTWEBD_SOCK_FILENO) {
144 					if (dup2(fd, PROC_GOTWEBD_SOCK_FILENO)
145 					    == -1)
146 						fatal("dup2");
147 				} else if (fcntl(fd, F_SETFD, 0) == -1)
148 					fatal("fcntl");
149 
150 				execvp(argv[0], nargv);
151 				fatal("%s: execvp", __func__);
152 				break;
153 			default:
154 				/* Close child end. */
155 				close(fd);
156 				break;
157 			}
158 		}
159 	}
160 
161 	free(nargv);
162 }
163 
164 void
165 proc_connect(struct privsep *ps)
166 {
167 	struct imsgev *iev;
168 	unsigned int src, dst, inst;
169 
170 	/* Don't distribute any sockets if we are not really going to run. */
171 	if (ps->ps_noaction)
172 		return;
173 
174 	for (dst = 0; dst < PROC_MAX; dst++) {
175 		/* We don't communicate with ourselves. */
176 		if (dst == PROC_GOTWEBD)
177 			continue;
178 
179 		for (inst = 0; inst < ps->ps_instances[dst]; inst++) {
180 			iev = &ps->ps_ievs[dst][inst];
181 			imsg_init(&iev->ibuf, ps->ps_pp->pp_pipes[dst][inst]);
182 			event_set(&iev->ev, iev->ibuf.fd, iev->events,
183 			    iev->handler, iev->data);
184 			event_add(&iev->ev, NULL);
185 		}
186 	}
187 
188 	/* Distribute the socketpair()s for everyone. */
189 	for (src = 0; src < PROC_MAX; src++)
190 		for (dst = src; dst < PROC_MAX; dst++) {
191 			/* Parent already distributed its fds. */
192 			if (src == PROC_GOTWEBD || dst == PROC_GOTWEBD)
193 				continue;
194 
195 			proc_open(ps, src, dst);
196 		}
197 }
198 
199 void
200 proc_init(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc,
201     int argc, char **argv, enum privsep_procid proc_id)
202 {
203 	struct privsep_proc *p = NULL;
204 	struct privsep_pipes *pa, *pb;
205 	unsigned int proc;
206 	unsigned int dst;
207 	int fds[2];
208 
209 	/* Don't initiate anything if we are not really going to run. */
210 	if (ps->ps_noaction)
211 		return;
212 
213 	if (proc_id == PROC_GOTWEBD) {
214 		privsep_process = PROC_GOTWEBD;
215 		proc_setup(ps, procs, nproc);
216 
217 		/*
218 		 * Create the children sockets so we can use them
219 		 * to distribute the rest of the socketpair()s using
220 		 * proc_connect() later.
221 		 */
222 		for (dst = 0; dst < PROC_MAX; dst++) {
223 			/* Don't create socket for ourselves. */
224 			if (dst == PROC_GOTWEBD)
225 				continue;
226 
227 			for (proc = 0; proc < ps->ps_instances[dst]; proc++) {
228 				pa = &ps->ps_pipes[PROC_GOTWEBD][0];
229 				pb = &ps->ps_pipes[dst][proc];
230 				if (socketpair(AF_UNIX,
231 				    SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC,
232 				    PF_UNSPEC, fds) == -1)
233 					fatal("%s: socketpair", __func__);
234 
235 				pa->pp_pipes[dst][proc] = fds[0];
236 				pb->pp_pipes[PROC_GOTWEBD][0] = fds[1];
237 			}
238 		}
239 
240 		/* Engage! */
241 		proc_exec(ps, procs, nproc, argc, argv);
242 		return;
243 	}
244 
245 	/* Initialize a child */
246 	for (proc = 0; proc < nproc; proc++) {
247 		if (procs[proc].p_id != proc_id)
248 			continue;
249 		p = &procs[proc];
250 		break;
251 	}
252 	if (p == NULL || p->p_init == NULL)
253 		fatalx("%s: process %d missing process initialization",
254 		    __func__, proc_id);
255 
256 	p->p_init(ps, p);
257 
258 	fatalx("failed to initiate child process");
259 }
260 
261 void
262 proc_accept(struct privsep *ps, int fd, enum privsep_procid dst,
263     unsigned int n)
264 {
265 	struct privsep_pipes *pp = ps->ps_pp;
266 	struct imsgev *iev;
267 
268 	if (ps->ps_ievs[dst] == NULL) {
269 #if DEBUG > 1
270 		log_debug("%s: %s src %d %d to dst %d %d not connected",
271 		    __func__, ps->ps_title[privsep_process],
272 		    privsep_process, ps->ps_instance + 1,
273 		    dst, n + 1);
274 #endif
275 		close(fd);
276 		return;
277 	}
278 
279 	if (pp->pp_pipes[dst][n] != -1) {
280 		log_warnx("%s: duplicated descriptor", __func__);
281 		close(fd);
282 		return;
283 	} else
284 		pp->pp_pipes[dst][n] = fd;
285 
286 	iev = &ps->ps_ievs[dst][n];
287 	imsg_init(&iev->ibuf, fd);
288 	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev->data);
289 	event_add(&iev->ev, NULL);
290 }
291 
292 void
293 proc_setup(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc)
294 {
295 	unsigned int i, j, src, dst, id;
296 	struct privsep_pipes *pp;
297 
298 	/* Initialize parent title, ps_instances and procs. */
299 	ps->ps_title[PROC_GOTWEBD] = "parent";
300 
301 	for (src = 0; src < PROC_MAX; src++)
302 		/* Default to 1 process instance */
303 		if (ps->ps_instances[src] < 1)
304 			ps->ps_instances[src] = 1;
305 
306 	for (src = 0; src < nproc; src++) {
307 		procs[src].p_ps = ps;
308 		if (procs[src].p_cb == NULL)
309 			procs[src].p_cb = proc_dispatch_null;
310 
311 		id = procs[src].p_id;
312 		ps->ps_title[id] = procs[src].p_title;
313 		ps->ps_ievs[id] = calloc(ps->ps_instances[id],
314 		    sizeof(struct imsgev));
315 		if (ps->ps_ievs[id] == NULL)
316 			fatal("%s: calloc", __func__);
317 
318 		/* With this set up, we are ready to call imsg_init(). */
319 		for (i = 0; i < ps->ps_instances[id]; i++) {
320 			ps->ps_ievs[id][i].handler = proc_dispatch;
321 			ps->ps_ievs[id][i].events = EV_READ;
322 			ps->ps_ievs[id][i].proc = &procs[src];
323 			ps->ps_ievs[id][i].data = &ps->ps_ievs[id][i];
324 		}
325 	}
326 
327 	/*
328 	 * Allocate pipes for all process instances (incl. parent)
329 	 *
330 	 * - ps->ps_pipes: N:M mapping
331 	 * N source processes connected to M destination processes:
332 	 * [src][instances][dst][instances], for example
333 	 * [PROC_RELAY][3][PROC_CA][3]
334 	 *
335 	 * - ps->ps_pp: per-process 1:M part of ps->ps_pipes
336 	 * Each process instance has a destination array of socketpair fds:
337 	 * [dst][instances], for example
338 	 * [PROC_GOTWEBD][0]
339 	 */
340 	for (src = 0; src < PROC_MAX; src++) {
341 		/* Allocate destination array for each process */
342 		ps->ps_pipes[src] = calloc(ps->ps_instances[src],
343 		    sizeof(struct privsep_pipes));
344 		if (ps->ps_pipes[src] == NULL)
345 			fatal("%s: calloc", __func__);
346 
347 		for (i = 0; i < ps->ps_instances[src]; i++) {
348 			pp = &ps->ps_pipes[src][i];
349 
350 			for (dst = 0; dst < PROC_MAX; dst++) {
351 				/* Allocate maximum fd integers */
352 				pp->pp_pipes[dst] =
353 				    calloc(ps->ps_instances[dst],
354 				    sizeof(int));
355 				if (pp->pp_pipes[dst] == NULL)
356 					fatal("%s: calloc", __func__);
357 
358 				/* Mark fd as unused */
359 				for (j = 0; j < ps->ps_instances[dst]; j++)
360 					pp->pp_pipes[dst][j] = -1;
361 			}
362 		}
363 	}
364 
365 	ps->ps_pp = &ps->ps_pipes[privsep_process][ps->ps_instance];
366 }
367 
368 void
369 proc_kill(struct privsep *ps)
370 {
371 	char *cause;
372 	pid_t pid;
373 	int len, status;
374 
375 	if (privsep_process != PROC_GOTWEBD)
376 		return;
377 
378 	proc_close(ps);
379 
380 	do {
381 		pid = waitpid(WAIT_ANY, &status, 0);
382 		if (pid <= 0)
383 			continue;
384 
385 		if (WIFSIGNALED(status)) {
386 			len = asprintf(&cause, "terminated; signal %d",
387 			    WTERMSIG(status));
388 		} else if (WIFEXITED(status)) {
389 			if (WEXITSTATUS(status) != 0)
390 				len = asprintf(&cause, "exited abnormally");
391 			else
392 				len = 0;
393 		} else
394 			len = -1;
395 
396 		if (len == 0) {
397 			/* child exited OK, don't print a warning message */
398 		} else if (len != -1) {
399 			log_warnx("lost child: pid %u %s", pid, cause);
400 			free(cause);
401 		} else
402 			log_warnx("lost child: pid %u", pid);
403 	} while (pid != -1 || (pid == -1 && errno == EINTR));
404 }
405 
406 void
407 proc_open(struct privsep *ps, int src, int dst)
408 {
409 	struct privsep_pipes *pa, *pb;
410 	struct privsep_fd pf;
411 	int fds[2];
412 	unsigned int i, j;
413 
414 	/* Exchange pipes between process. */
415 	for (i = 0; i < ps->ps_instances[src]; i++) {
416 		for (j = 0; j < ps->ps_instances[dst]; j++) {
417 			/* Don't create sockets for ourself. */
418 			if (src == dst && i == j)
419 				continue;
420 
421 			pa = &ps->ps_pipes[src][i];
422 			pb = &ps->ps_pipes[dst][j];
423 			if (socketpair(AF_UNIX,
424 			    SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC,
425 			    PF_UNSPEC, fds) == -1)
426 				fatal("%s: socketpair", __func__);
427 
428 			pa->pp_pipes[dst][j] = fds[0];
429 			pb->pp_pipes[src][i] = fds[1];
430 
431 			pf.pf_procid = src;
432 			pf.pf_instance = i;
433 			if (proc_compose_imsg(ps, dst, j, IMSG_CTL_PROCFD,
434 			    -1, pb->pp_pipes[src][i], &pf, sizeof(pf)) == -1)
435 				fatal("%s: proc_compose_imsg", __func__);
436 
437 			pf.pf_procid = dst;
438 			pf.pf_instance = j;
439 			if (proc_compose_imsg(ps, src, i, IMSG_CTL_PROCFD,
440 			    -1, pa->pp_pipes[dst][j], &pf, sizeof(pf)) == -1)
441 				fatal("%s: proc_compose_imsg", __func__);
442 
443 			/*
444 			 * We have to flush to send the descriptors and close
445 			 * them to avoid the fd ramp on startup.
446 			 */
447 			if (proc_flush_imsg(ps, src, i) == -1 ||
448 			    proc_flush_imsg(ps, dst, j) == -1)
449 				fatal("%s: imsg_flush", __func__);
450 		}
451 	}
452 }
453 
454 void
455 proc_close(struct privsep *ps)
456 {
457 	unsigned int dst, n;
458 	struct privsep_pipes *pp;
459 
460 	if (ps == NULL)
461 		return;
462 
463 	pp = ps->ps_pp;
464 
465 	for (dst = 0; dst < PROC_MAX; dst++) {
466 		if (ps->ps_ievs[dst] == NULL)
467 			continue;
468 
469 		for (n = 0; n < ps->ps_instances[dst]; n++) {
470 			if (pp->pp_pipes[dst][n] == -1)
471 				continue;
472 
473 			/* Cancel the fd, close and invalidate the fd */
474 			event_del(&(ps->ps_ievs[dst][n].ev));
475 			imsg_clear(&(ps->ps_ievs[dst][n].ibuf));
476 			close(pp->pp_pipes[dst][n]);
477 			pp->pp_pipes[dst][n] = -1;
478 		}
479 		free(ps->ps_ievs[dst]);
480 	}
481 }
482 
483 void
484 proc_shutdown(struct privsep_proc *p)
485 {
486 	struct privsep *ps = p->p_ps;
487 
488 	if (p->p_shutdown != NULL)
489 		(*p->p_shutdown)();
490 
491 	proc_close(ps);
492 
493 	log_info("%s, %s exiting, pid %d", getprogname(), p->p_title, getpid());
494 
495 	exit(0);
496 }
497 
498 void
499 proc_sig_handler(int sig, short event, void *arg)
500 {
501 	struct privsep_proc *p = arg;
502 
503 	switch (sig) {
504 	case SIGINT:
505 	case SIGTERM:
506 		proc_shutdown(p);
507 		break;
508 	case SIGCHLD:
509 	case SIGHUP:
510 	case SIGPIPE:
511 	case SIGUSR1:
512 		/* ignore */
513 		break;
514 	default:
515 		fatalx("proc_sig_handler: unexpected signal");
516 		/* NOTREACHED */
517 	}
518 }
519 
520 void
521 proc_run(struct privsep *ps, struct privsep_proc *p,
522     struct privsep_proc *procs, unsigned int nproc,
523     void (*run)(struct privsep *, struct privsep_proc *, void *), void *arg)
524 {
525 	struct passwd *pw;
526 	const char *root;
527 
528 	log_procinit(p->p_title);
529 
530 	/* Set the process group of the current process */
531 	setpgid(0, 0);
532 
533 	/* Use non-standard user */
534 	if (p->p_pw != NULL)
535 		pw = p->p_pw;
536 	else
537 		pw = ps->ps_pw;
538 
539 	/* Change root directory */
540 	if (p->p_chroot != NULL)
541 		root = p->p_chroot;
542 	else
543 		root = pw->pw_dir;
544 
545 	if (chroot(root) == -1)
546 		fatal("proc_run: chroot");
547 	if (chdir("/") == -1)
548 		fatal("proc_run: chdir(\"/\")");
549 
550 	privsep_process = p->p_id;
551 
552 	setproctitle("%s", p->p_title);
553 
554 	if (setgroups(1, &pw->pw_gid) ||
555 	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
556 	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
557 		fatal("proc_run: cannot drop privileges");
558 
559 	event_init();
560 
561 	signal_set(&ps->ps_evsigint, SIGINT, proc_sig_handler, p);
562 	signal_set(&ps->ps_evsigterm, SIGTERM, proc_sig_handler, p);
563 	signal_set(&ps->ps_evsigchld, SIGCHLD, proc_sig_handler, p);
564 	signal_set(&ps->ps_evsighup, SIGHUP, proc_sig_handler, p);
565 	signal_set(&ps->ps_evsigpipe, SIGPIPE, proc_sig_handler, p);
566 	signal_set(&ps->ps_evsigusr1, SIGUSR1, proc_sig_handler, p);
567 
568 	signal_add(&ps->ps_evsigint, NULL);
569 	signal_add(&ps->ps_evsigterm, NULL);
570 	signal_add(&ps->ps_evsigchld, NULL);
571 	signal_add(&ps->ps_evsighup, NULL);
572 	signal_add(&ps->ps_evsigpipe, NULL);
573 	signal_add(&ps->ps_evsigusr1, NULL);
574 
575 	proc_setup(ps, procs, nproc);
576 	proc_accept(ps, PROC_GOTWEBD_SOCK_FILENO, PROC_GOTWEBD, 0);
577 
578 	DPRINTF("%s: %s %d/%d, pid %d", __func__, p->p_title,
579 	    ps->ps_instance + 1, ps->ps_instances[p->p_id], getpid());
580 
581 	if (run != NULL)
582 		run(ps, p, arg);
583 
584 	event_dispatch();
585 
586 	proc_shutdown(p);
587 }
588 
589 void
590 proc_dispatch(int fd, short event, void *arg)
591 {
592 	struct imsgev *iev = arg;
593 	struct privsep_proc *p = iev->proc;
594 	struct privsep *ps = p->p_ps;
595 	struct imsgbuf *ibuf;
596 	struct imsg imsg;
597 	ssize_t n;
598 	int verbose;
599 	const char *title;
600 	struct privsep_fd pf;
601 
602 	title = ps->ps_title[privsep_process];
603 	ibuf = &iev->ibuf;
604 
605 	if (event & EV_READ) {
606 		n = imsg_read(ibuf);
607 		if (n == -1 && errno != EAGAIN)
608 			fatal("%s: imsg_read", __func__);
609 		if (n == 0) {
610 			/* this pipe is dead, so remove the event handler */
611 			event_del(&iev->ev);
612 			event_loopexit(NULL);
613 			return;
614 		}
615 	}
616 
617 	if (event & EV_WRITE) {
618 		n = msgbuf_write(&ibuf->w);
619 		if (n == -1 && errno != EAGAIN)
620 			fatal("%s: msgbuf_write", __func__);
621 		if (n == 0) {
622 			/* this pipe is dead, so remove the event handler */
623 			event_del(&iev->ev);
624 			event_loopexit(NULL);
625 			return;
626 		}
627 	}
628 
629 	for (;;) {
630 		n = imsg_get(ibuf, &imsg);
631 		if (n == -1)
632 			fatal("%s: imsg_get", __func__);
633 		if (n == 0)
634 			break;
635 
636 #if DEBUG > 1
637 		log_debug("%s: %s %d got imsg %d peerid %d from %s %d",
638 		    __func__, title, ps->ps_instance + 1,
639 		    imsg.hdr.type, imsg.hdr.peerid, p->p_title, imsg.hdr.pid);
640 #endif
641 
642 		/*
643 		 * Check the message with the program callback
644 		 */
645 		if ((p->p_cb)(fd, p, &imsg) == 0) {
646 			/* Message was handled by the callback, continue */
647 			imsg_free(&imsg);
648 			continue;
649 		}
650 
651 		/*
652 		 * Generic message handling
653 		 */
654 		switch (imsg.hdr.type) {
655 		case IMSG_CTL_VERBOSE:
656 			log_info("%s", __func__);
657 			IMSG_SIZE_CHECK(&imsg, &verbose);
658 			memcpy(&verbose, imsg.data, sizeof(verbose));
659 			log_setverbose(verbose);
660 			break;
661 		case IMSG_CTL_PROCFD:
662 			IMSG_SIZE_CHECK(&imsg, &pf);
663 			memcpy(&pf, imsg.data, sizeof(pf));
664 			proc_accept(ps, imsg.fd, pf.pf_procid,
665 			    pf.pf_instance);
666 			break;
667 		default:
668 			log_warnx("%s: %s %d got invalid imsg %d peerid %d "
669 			    "from %s %d",
670 			    __func__, title, ps->ps_instance + 1,
671 			    imsg.hdr.type, imsg.hdr.peerid,
672 			    p->p_title, imsg.hdr.pid);
673 		}
674 		imsg_free(&imsg);
675 	}
676 	imsg_event_add(iev);
677 }
678 
679 int
680 proc_dispatch_null(int fd, struct privsep_proc *p, struct imsg *imsg)
681 {
682 	return (-1);
683 }
684 
685 /*
686  * imsg helper functions
687  */
688 
689 void
690 imsg_event_add(struct imsgev *iev)
691 {
692 	if (iev->handler == NULL) {
693 		imsg_flush(&iev->ibuf);
694 		return;
695 	}
696 
697 	iev->events = EV_READ;
698 	if (iev->ibuf.w.queued)
699 		iev->events |= EV_WRITE;
700 
701 	event_del(&iev->ev);
702 	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev->data);
703 	event_add(&iev->ev, NULL);
704 }
705 
706 int
707 imsg_compose_event(struct imsgev *iev, uint16_t type, uint32_t peerid,
708     pid_t pid, int fd, void *data, uint16_t datalen)
709 {
710 	int ret;
711 
712 	ret = imsg_compose(&iev->ibuf, type, peerid, pid, fd, data, datalen);
713 	if (ret == -1)
714 		return (ret);
715 	imsg_event_add(iev);
716 	return (ret);
717 }
718 
719 int
720 imsg_composev_event(struct imsgev *iev, uint16_t type, uint32_t peerid,
721     pid_t pid, int fd, const struct iovec *iov, int iovcnt)
722 {
723 	int ret;
724 
725 	ret = imsg_composev(&iev->ibuf, type, peerid, pid, fd, iov, iovcnt);
726 	if (ret == -1)
727 		return (ret);
728 	imsg_event_add(iev);
729 	return (ret);
730 }
731 
732 void
733 proc_range(struct privsep *ps, enum privsep_procid id, int *n, int *m)
734 {
735 	if (*n == -1) {
736 		/* Use a range of all target instances */
737 		*n = 0;
738 		*m = ps->ps_instances[id];
739 	} else {
740 		/* Use only a single slot of the specified peer process */
741 		*m = *n + 1;
742 	}
743 }
744 
745 int
746 proc_compose_imsg(struct privsep *ps, enum privsep_procid id, int n,
747     uint16_t type, uint32_t peerid, int fd, void *data, uint16_t datalen)
748 {
749 	int m;
750 
751 	proc_range(ps, id, &n, &m);
752 	for (; n < m; n++) {
753 		if (imsg_compose_event(&ps->ps_ievs[id][n],
754 		    type, peerid, ps->ps_instance + 1, fd, data, datalen) == -1)
755 			return (-1);
756 	}
757 
758 	return (0);
759 }
760 
761 int
762 proc_compose(struct privsep *ps, enum privsep_procid id,
763     uint16_t type, void *data, uint16_t datalen)
764 {
765 	return (proc_compose_imsg(ps, id, -1, type, -1, -1, data, datalen));
766 }
767 
768 int
769 proc_composev_imsg(struct privsep *ps, enum privsep_procid id, int n,
770     uint16_t type, uint32_t peerid, int fd, const struct iovec *iov, int iovcnt)
771 {
772 	int m;
773 
774 	proc_range(ps, id, &n, &m);
775 	for (; n < m; n++)
776 		if (imsg_composev_event(&ps->ps_ievs[id][n],
777 		    type, peerid, ps->ps_instance + 1, fd, iov, iovcnt) == -1)
778 			return (-1);
779 
780 	return (0);
781 }
782 
783 int
784 proc_composev(struct privsep *ps, enum privsep_procid id,
785     uint16_t type, const struct iovec *iov, int iovcnt)
786 {
787 	return (proc_composev_imsg(ps, id, -1, type, -1, -1, iov, iovcnt));
788 }
789 
790 int
791 proc_forward_imsg(struct privsep *ps, struct imsg *imsg,
792     enum privsep_procid id, int n)
793 {
794 	return (proc_compose_imsg(ps, id, n, imsg->hdr.type,
795 	    imsg->hdr.peerid, imsg->fd, imsg->data, IMSG_DATA_SIZE(imsg)));
796 }
797 
798 struct imsgbuf *
799 proc_ibuf(struct privsep *ps, enum privsep_procid id, int n)
800 {
801 	int m;
802 
803 	proc_range(ps, id, &n, &m);
804 	return (&ps->ps_ievs[id][n].ibuf);
805 }
806 
807 struct imsgev *
808 proc_iev(struct privsep *ps, enum privsep_procid id, int n)
809 {
810 	int m;
811 
812 	proc_range(ps, id, &n, &m);
813 	return (&ps->ps_ievs[id][n]);
814 }
815 
816 /* This function should only be called with care as it breaks async I/O */
817 int
818 proc_flush_imsg(struct privsep *ps, enum privsep_procid id, int n)
819 {
820 	struct imsgbuf *ibuf;
821 	int m, ret = 0;
822 
823 	proc_range(ps, id, &n, &m);
824 	for (; n < m; n++) {
825 		ibuf = proc_ibuf(ps, id, n);
826 		if (ibuf == NULL)
827 			return (-1);
828 		do {
829 			ret = imsg_flush(ibuf);
830 		} while (ret == -1 && errno == EAGAIN);
831 		if (ret == -1)
832 			break;
833 		imsg_event_add(&ps->ps_ievs[id][n]);
834 	}
835 
836 	return (ret);
837 }