xref: /openbsd/usr.sbin/snmpd/proc.c (revision 905646f0)
1 /*	$OpenBSD: proc.c,v 1.27 2020/06/30 17:11:49 martijn Exp $	*/
2 
3 /*
4  * Copyright (c) 2010 - 2016 Reyk Floeter <reyk@openbsd.org>
5  * Copyright (c) 2008 Pierre-Yves Ritschard <pyr@openbsd.org>
6  *
7  * Permission to use, copy, modify, and distribute this software for any
8  * purpose with or without fee is hereby granted, provided that the above
9  * copyright notice and this permission notice appear in all copies.
10  *
11  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
17  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18  */
19 
20 #include <sys/types.h>
21 #include <sys/queue.h>
22 #include <sys/socket.h>
23 #include <sys/wait.h>
24 
25 #include <fcntl.h>
26 #include <stdio.h>
27 #include <stdlib.h>
28 #include <unistd.h>
29 #include <string.h>
30 #include <errno.h>
31 #include <signal.h>
32 #include <paths.h>
33 #include <pwd.h>
34 #include <event.h>
35 #include <imsg.h>
36 
37 #include "snmpd.h"
38 
39 void	 proc_exec(struct privsep *, struct privsep_proc *, unsigned int, int,
40 	    int, char **);
41 void	 proc_setup(struct privsep *, struct privsep_proc *, unsigned int);
42 void	 proc_open(struct privsep *, int, int);
43 void	 proc_accept(struct privsep *, int, enum privsep_procid,
44 	    unsigned int);
45 void	 proc_close(struct privsep *);
46 int	 proc_ispeer(struct privsep_proc *, unsigned int, enum privsep_procid);
47 void	 proc_shutdown(struct privsep_proc *);
48 void	 proc_sig_handler(int, short, void *);
49 void	 proc_range(struct privsep *, enum privsep_procid, int *, int *);
50 int	 proc_dispatch_null(int, struct privsep_proc *, struct imsg *);
51 
52 int
53 proc_ispeer(struct privsep_proc *procs, unsigned int nproc,
54     enum privsep_procid type)
55 {
56 	unsigned int	i;
57 
58 	for (i = 0; i < nproc; i++)
59 		if (procs[i].p_id == type)
60 			return (1);
61 	return (0);
62 }
63 
64 enum privsep_procid
65 proc_getid(struct privsep_proc *procs, unsigned int nproc,
66     const char *proc_name)
67 {
68 	struct privsep_proc	*p;
69 	unsigned int		 proc;
70 
71 	for (proc = 0; proc < nproc; proc++) {
72 		p = &procs[proc];
73 		if (strcmp(p->p_title, proc_name))
74 			continue;
75 
76 		return (p->p_id);
77 	}
78 
79 	return (PROC_MAX);
80 }
81 
82 void
83 proc_exec(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc,
84     int debug, int argc, char **argv)
85 {
86 	unsigned int		 proc, nargc, i, proc_i;
87 	char			**nargv;
88 	struct privsep_proc	*p;
89 	char			 num[32];
90 	int			 fd;
91 
92 	/* Prepare the new process argv. */
93 	nargv = calloc(argc + 5, sizeof(char *));
94 	if (nargv == NULL)
95 		fatal("%s: calloc", __func__);
96 
97 	/* Copy call argument first. */
98 	nargc = 0;
99 	nargv[nargc++] = argv[0];
100 
101 	/* Set process name argument and save the position. */
102 	nargv[nargc++] = "-P";
103 	proc_i = nargc;
104 	nargc++;
105 
106 	/* Point process instance arg to stack and copy the original args. */
107 	nargv[nargc++] = "-I";
108 	nargv[nargc++] = num;
109 	for (i = 1; i < (unsigned int) argc; i++)
110 		nargv[nargc++] = argv[i];
111 
112 	nargv[nargc] = NULL;
113 
114 	for (proc = 0; proc < nproc; proc++) {
115 		p = &procs[proc];
116 
117 		/* Update args with process title. */
118 		nargv[proc_i] = (char *)(uintptr_t)p->p_title;
119 
120 		/* Fire children processes. */
121 		for (i = 0; i < ps->ps_instances[p->p_id]; i++) {
122 			/* Update the process instance number. */
123 			snprintf(num, sizeof(num), "%u", i);
124 
125 			fd = ps->ps_pipes[p->p_id][i].pp_pipes[PROC_PARENT][0];
126 			ps->ps_pipes[p->p_id][i].pp_pipes[PROC_PARENT][0] = -1;
127 
128 			switch (fork()) {
129 			case -1:
130 				fatal("%s: fork", __func__);
131 				break;
132 			case 0:
133 				/* First create a new session */
134 				if (setsid() == -1)
135 					fatal("setsid");
136 
137 				/* Prepare parent socket. */
138 				if (fd != PROC_PARENT_SOCK_FILENO) {
139 					if (dup2(fd, PROC_PARENT_SOCK_FILENO)
140 					    == -1)
141 						fatal("dup2");
142 				} else if (fcntl(fd, F_SETFD, 0) == -1)
143 					fatal("fcntl");
144 
145 				/* Daemons detach from terminal. */
146 				if (!debug && (fd =
147 				    open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
148 					(void)dup2(fd, STDIN_FILENO);
149 					(void)dup2(fd, STDOUT_FILENO);
150 					(void)dup2(fd, STDERR_FILENO);
151 					if (fd > 2)
152 						(void)close(fd);
153 				}
154 
155 				execvp(argv[0], nargv);
156 				fatal("%s: execvp", __func__);
157 				break;
158 			default:
159 				/* Close child end. */
160 				close(fd);
161 				break;
162 			}
163 		}
164 	}
165 	free(nargv);
166 }
167 
168 void
169 proc_connect(struct privsep *ps)
170 {
171 	struct imsgev		*iev;
172 	unsigned int		 src, dst, inst;
173 
174 	/* Don't distribute any sockets if we are not really going to run. */
175 	if (ps->ps_noaction)
176 		return;
177 
178 	for (dst = 0; dst < PROC_MAX; dst++) {
179 		/* We don't communicate with ourselves. */
180 		if (dst == PROC_PARENT)
181 			continue;
182 
183 		for (inst = 0; inst < ps->ps_instances[dst]; inst++) {
184 			iev = &ps->ps_ievs[dst][inst];
185 			imsg_init(&iev->ibuf, ps->ps_pp->pp_pipes[dst][inst]);
186 			event_set(&iev->ev, iev->ibuf.fd, iev->events,
187 			    iev->handler, iev->data);
188 			event_add(&iev->ev, NULL);
189 		}
190 	}
191 
192 	/* Distribute the socketpair()s for everyone. */
193 	for (src = 0; src < PROC_MAX; src++)
194 		for (dst = src; dst < PROC_MAX; dst++) {
195 			/* Parent already distributed its fds. */
196 			if (src == PROC_PARENT || dst == PROC_PARENT)
197 				continue;
198 
199 			proc_open(ps, src, dst);
200 		}
201 }
202 
203 void
204 proc_init(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc,
205     int debug, int argc, char **argv, enum privsep_procid proc_id)
206 {
207 	struct privsep_proc	*p = NULL;
208 	struct privsep_pipes	*pa, *pb;
209 	unsigned int		 proc;
210 	unsigned int		 dst;
211 	int			 fds[2];
212 
213 	/* Don't initiate anything if we are not really going to run. */
214 	if (ps->ps_noaction)
215 		return;
216 
217 	if (proc_id == PROC_PARENT) {
218 		privsep_process = PROC_PARENT;
219 		proc_setup(ps, procs, nproc);
220 
221 		/*
222 		 * Create the children sockets so we can use them
223 		 * to distribute the rest of the socketpair()s using
224 		 * proc_connect() later.
225 		 */
226 		for (dst = 0; dst < PROC_MAX; dst++) {
227 			/* Don't create socket for ourselves. */
228 			if (dst == PROC_PARENT)
229 				continue;
230 
231 			for (proc = 0; proc < ps->ps_instances[dst]; proc++) {
232 				pa = &ps->ps_pipes[PROC_PARENT][0];
233 				pb = &ps->ps_pipes[dst][proc];
234 				if (socketpair(AF_UNIX,
235 				    SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC,
236 				    PF_UNSPEC, fds) == -1)
237 					fatal("%s: socketpair", __func__);
238 
239 				pa->pp_pipes[dst][proc] = fds[0];
240 				pb->pp_pipes[PROC_PARENT][0] = fds[1];
241 			}
242 		}
243 
244 		/* Engage! */
245 		proc_exec(ps, procs, nproc, debug, argc, argv);
246 		return;
247 	}
248 
249 	/* Initialize a child */
250 	for (proc = 0; proc < nproc; proc++) {
251 		if (procs[proc].p_id != proc_id)
252 			continue;
253 		p = &procs[proc];
254 		break;
255 	}
256 	if (p == NULL || p->p_init == NULL)
257 		fatalx("%s: process %d missing process initialization",
258 		    __func__, proc_id);
259 
260 	p->p_init(ps, p);
261 
262 	fatalx("failed to initiate child process");
263 }
264 
265 void
266 proc_accept(struct privsep *ps, int fd, enum privsep_procid dst,
267     unsigned int n)
268 {
269 	struct privsep_pipes	*pp = ps->ps_pp;
270 	struct imsgev		*iev;
271 
272 	if (ps->ps_ievs[dst] == NULL) {
273 #if DEBUG > 1
274 		log_debug("%s: %s src %d %d to dst %d %d not connected",
275 		    __func__, ps->ps_title[privsep_process],
276 		    privsep_process, ps->ps_instance + 1,
277 		    dst, n + 1);
278 #endif
279 		close(fd);
280 		return;
281 	}
282 
283 	if (pp->pp_pipes[dst][n] != -1) {
284 		log_warnx("%s: duplicated descriptor", __func__);
285 		close(fd);
286 		return;
287 	} else
288 		pp->pp_pipes[dst][n] = fd;
289 
290 	iev = &ps->ps_ievs[dst][n];
291 	imsg_init(&iev->ibuf, fd);
292 	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev->data);
293 	event_add(&iev->ev, NULL);
294 }
295 
296 void
297 proc_setup(struct privsep *ps, struct privsep_proc *procs, unsigned int nproc)
298 {
299 	unsigned int		 i, j, src, dst, id;
300 	struct privsep_pipes	*pp;
301 
302 	/* Initialize parent title, ps_instances and procs. */
303 	ps->ps_title[PROC_PARENT] = "parent";
304 
305 	for (src = 0; src < PROC_MAX; src++)
306 		/* Default to 1 process instance */
307 		if (ps->ps_instances[src] < 1)
308 			ps->ps_instances[src] = 1;
309 
310 	for (src = 0; src < nproc; src++) {
311 		procs[src].p_ps = ps;
312 		if (procs[src].p_cb == NULL)
313 			procs[src].p_cb = proc_dispatch_null;
314 
315 		id = procs[src].p_id;
316 		ps->ps_title[id] = procs[src].p_title;
317 		if ((ps->ps_ievs[id] = calloc(ps->ps_instances[id],
318 		    sizeof(struct imsgev))) == NULL)
319 			fatal("%s: calloc", __func__);
320 
321 		/* With this set up, we are ready to call imsg_init(). */
322 		for (i = 0; i < ps->ps_instances[id]; i++) {
323 			ps->ps_ievs[id][i].handler = proc_dispatch;
324 			ps->ps_ievs[id][i].events = EV_READ;
325 			ps->ps_ievs[id][i].proc = &procs[src];
326 			ps->ps_ievs[id][i].data = &ps->ps_ievs[id][i];
327 		}
328 	}
329 
330 	/*
331 	 * Allocate pipes for all process instances (incl. parent)
332 	 *
333 	 * - ps->ps_pipes: N:M mapping
334 	 * N source processes connected to M destination processes:
335 	 * [src][instances][dst][instances], for example
336 	 * [PROC_RELAY][3][PROC_CA][3]
337 	 *
338 	 * - ps->ps_pp: per-process 1:M part of ps->ps_pipes
339 	 * Each process instance has a destination array of socketpair fds:
340 	 * [dst][instances], for example
341 	 * [PROC_PARENT][0]
342 	 */
343 	for (src = 0; src < PROC_MAX; src++) {
344 		/* Allocate destination array for each process */
345 		if ((ps->ps_pipes[src] = calloc(ps->ps_instances[src],
346 		    sizeof(struct privsep_pipes))) == NULL)
347 			fatal("%s: calloc", __func__);
348 
349 		for (i = 0; i < ps->ps_instances[src]; i++) {
350 			pp = &ps->ps_pipes[src][i];
351 
352 			for (dst = 0; dst < PROC_MAX; dst++) {
353 				/* Allocate maximum fd integers */
354 				if ((pp->pp_pipes[dst] =
355 				    calloc(ps->ps_instances[dst],
356 				    sizeof(int))) == NULL)
357 					fatal("%s: calloc", __func__);
358 
359 				/* Mark fd as unused */
360 				for (j = 0; j < ps->ps_instances[dst]; j++)
361 					pp->pp_pipes[dst][j] = -1;
362 			}
363 		}
364 	}
365 
366 	ps->ps_pp = &ps->ps_pipes[privsep_process][ps->ps_instance];
367 }
368 
369 void
370 proc_kill(struct privsep *ps)
371 {
372 	char		*cause;
373 	pid_t		 pid;
374 	int		 len, status;
375 
376 	if (privsep_process != PROC_PARENT)
377 		return;
378 
379 	proc_close(ps);
380 
381 	do {
382 		pid = waitpid(WAIT_ANY, &status, 0);
383 		if (pid <= 0)
384 			continue;
385 
386 		if (WIFSIGNALED(status)) {
387 			len = asprintf(&cause, "terminated; signal %d",
388 			    WTERMSIG(status));
389 		} else if (WIFEXITED(status)) {
390 			if (WEXITSTATUS(status) != 0)
391 				len = asprintf(&cause, "exited abnormally");
392 			else
393 				len = 0;
394 		} else
395 			len = -1;
396 
397 		if (len == 0) {
398 			/* child exited OK, don't print a warning message */
399 		} else if (len != -1) {
400 			log_warnx("lost child: pid %u %s", pid, cause);
401 			free(cause);
402 		} else
403 			log_warnx("lost child: pid %u", pid);
404 	} while (pid != -1 || (pid == -1 && errno == EINTR));
405 }
406 
407 void
408 proc_open(struct privsep *ps, int src, int dst)
409 {
410 	struct privsep_pipes	*pa, *pb;
411 	struct privsep_fd	 pf;
412 	int			 fds[2];
413 	unsigned int		 i, j;
414 
415 	/* Exchange pipes between process. */
416 	for (i = 0; i < ps->ps_instances[src]; i++) {
417 		for (j = 0; j < ps->ps_instances[dst]; j++) {
418 			/* Don't create sockets for ourself. */
419 			if (src == dst && i == j)
420 				continue;
421 
422 			pa = &ps->ps_pipes[src][i];
423 			pb = &ps->ps_pipes[dst][j];
424 			if (socketpair(AF_UNIX,
425 			    SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC,
426 			    PF_UNSPEC, fds) == -1)
427 				fatal("%s: socketpair", __func__);
428 
429 			pa->pp_pipes[dst][j] = fds[0];
430 			pb->pp_pipes[src][i] = fds[1];
431 
432 			pf.pf_procid = src;
433 			pf.pf_instance = i;
434 			if (proc_compose_imsg(ps, dst, j, IMSG_CTL_PROCFD,
435 			    -1, pb->pp_pipes[src][i], &pf, sizeof(pf)) == -1)
436 				fatal("%s: proc_compose_imsg", __func__);
437 
438 			pf.pf_procid = dst;
439 			pf.pf_instance = j;
440 			if (proc_compose_imsg(ps, src, i, IMSG_CTL_PROCFD,
441 			    -1, pa->pp_pipes[dst][j], &pf, sizeof(pf)) == -1)
442 				fatal("%s: proc_compose_imsg", __func__);
443 
444 			/*
445 			 * We have to flush to send the descriptors and close
446 			 * them to avoid the fd ramp on startup.
447 			 */
448 			if (proc_flush_imsg(ps, src, i) == -1 ||
449 			    proc_flush_imsg(ps, dst, j) == -1)
450 				fatal("%s: imsg_flush", __func__);
451 		}
452 	}
453 }
454 
455 void
456 proc_close(struct privsep *ps)
457 {
458 	unsigned int		 dst, n;
459 	struct privsep_pipes	*pp;
460 
461 	if (ps == NULL)
462 		return;
463 
464 	pp = ps->ps_pp;
465 
466 	for (dst = 0; dst < PROC_MAX; dst++) {
467 		if (ps->ps_ievs[dst] == NULL)
468 			continue;
469 
470 		for (n = 0; n < ps->ps_instances[dst]; n++) {
471 			if (pp->pp_pipes[dst][n] == -1)
472 				continue;
473 
474 			/* Cancel the fd, close and invalidate the fd */
475 			event_del(&(ps->ps_ievs[dst][n].ev));
476 			imsg_clear(&(ps->ps_ievs[dst][n].ibuf));
477 			close(pp->pp_pipes[dst][n]);
478 			pp->pp_pipes[dst][n] = -1;
479 		}
480 		free(ps->ps_ievs[dst]);
481 	}
482 }
483 
484 void
485 proc_shutdown(struct privsep_proc *p)
486 {
487 	struct privsep	*ps = p->p_ps;
488 
489 	if (p->p_shutdown != NULL)
490 		(*p->p_shutdown)();
491 
492 	proc_close(ps);
493 
494 	log_info("%s exiting, pid %d", p->p_title, getpid());
495 
496 	exit(0);
497 }
498 
499 void
500 proc_sig_handler(int sig, short event, void *arg)
501 {
502 	struct privsep_proc	*p = arg;
503 
504 	switch (sig) {
505 	case SIGINT:
506 	case SIGTERM:
507 		proc_shutdown(p);
508 		break;
509 	case SIGCHLD:
510 	case SIGHUP:
511 	case SIGPIPE:
512 	case SIGUSR1:
513 		/* ignore */
514 		break;
515 	default:
516 		fatalx("%s: unexpected signal", __func__);
517 		/* NOTREACHED */
518 	}
519 }
520 
521 void
522 proc_run(struct privsep *ps, struct privsep_proc *p,
523     struct privsep_proc *procs, unsigned int nproc,
524     void (*run)(struct privsep *, struct privsep_proc *, void *), void *arg)
525 {
526 	struct passwd		*pw;
527 	const char		*root;
528 
529 	log_procinit(p->p_title);
530 
531 	/* Set the process group of the current process */
532 	setpgid(0, 0);
533 
534 	/* Use non-standard user */
535 	if (p->p_pw != NULL)
536 		pw = p->p_pw;
537 	else
538 		pw = ps->ps_pw;
539 
540 	/* Change root directory */
541 	if (p->p_chroot != NULL)
542 		root = p->p_chroot;
543 	else
544 		root = pw->pw_dir;
545 
546 	if (chroot(root) == -1)
547 		fatal("%s: chroot", __func__);
548 	if (chdir("/") == -1)
549 		fatal("%s: chdir(\"/\")", __func__);
550 
551 	privsep_process = p->p_id;
552 
553 	setproctitle("%s", p->p_title);
554 
555 	if (setgroups(1, &pw->pw_gid) ||
556 	    setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
557 	    setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid))
558 		fatal("%s: cannot drop privileges", __func__);
559 
560 	event_init();
561 
562 	signal_set(&ps->ps_evsigint, SIGINT, proc_sig_handler, p);
563 	signal_set(&ps->ps_evsigterm, SIGTERM, proc_sig_handler, p);
564 	signal_set(&ps->ps_evsigchld, SIGCHLD, proc_sig_handler, p);
565 	signal_set(&ps->ps_evsighup, SIGHUP, proc_sig_handler, p);
566 	signal_set(&ps->ps_evsigpipe, SIGPIPE, proc_sig_handler, p);
567 	signal_set(&ps->ps_evsigusr1, SIGUSR1, proc_sig_handler, p);
568 
569 	signal_add(&ps->ps_evsigint, NULL);
570 	signal_add(&ps->ps_evsigterm, NULL);
571 	signal_add(&ps->ps_evsigchld, NULL);
572 	signal_add(&ps->ps_evsighup, NULL);
573 	signal_add(&ps->ps_evsigpipe, NULL);
574 	signal_add(&ps->ps_evsigusr1, NULL);
575 
576 	proc_setup(ps, procs, nproc);
577 	proc_accept(ps, PROC_PARENT_SOCK_FILENO, PROC_PARENT, 0);
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 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
607 			fatal("%s: imsg_read", __func__);
608 		if (n == 0) {
609 			/* this pipe is dead, so remove the event handler */
610 			event_del(&iev->ev);
611 			event_loopexit(NULL);
612 			return;
613 		}
614 	}
615 
616 	if (event & EV_WRITE) {
617 		if ((n = msgbuf_write(&ibuf->w)) == -1 && errno != EAGAIN)
618 			fatal("%s: msgbuf_write", __func__);
619 		if (n == 0) {
620 			/* this pipe is dead, so remove the event handler */
621 			event_del(&iev->ev);
622 			event_loopexit(NULL);
623 			return;
624 		}
625 	}
626 
627 	for (;;) {
628 		if ((n = imsg_get(ibuf, &imsg)) == -1)
629 			fatal("%s: imsg_get", __func__);
630 		if (n == 0)
631 			break;
632 
633 #if DEBUG > 1
634 		log_debug("%s: %s %d got imsg %d peerid %d from %s %d",
635 		    __func__, title, ps->ps_instance + 1,
636 		    imsg.hdr.type, imsg.hdr.peerid, p->p_title, imsg.hdr.pid);
637 #endif
638 
639 		/*
640 		 * Check the message with the program callback
641 		 */
642 		if ((p->p_cb)(fd, p, &imsg) == 0) {
643 			/* Message was handled by the callback, continue */
644 			imsg_free(&imsg);
645 			continue;
646 		}
647 
648 		/*
649 		 * Generic message handling
650 		 */
651 		switch (imsg.hdr.type) {
652 		case IMSG_CTL_VERBOSE:
653 			IMSG_SIZE_CHECK(&imsg, &verbose);
654 			memcpy(&verbose, imsg.data, sizeof(verbose));
655 			log_setverbose(verbose);
656 			break;
657 		case IMSG_CTL_PROCFD:
658 			IMSG_SIZE_CHECK(&imsg, &pf);
659 			memcpy(&pf, imsg.data, sizeof(pf));
660 			proc_accept(ps, imsg.fd, pf.pf_procid,
661 			    pf.pf_instance);
662 			break;
663 		default:
664 			fatalx("%s: %s %d got invalid imsg %d peerid %d "
665 			    "from %s %d",
666 			    __func__, title, ps->ps_instance + 1,
667 			    imsg.hdr.type, imsg.hdr.peerid,
668 			    p->p_title, imsg.hdr.pid);
669 		}
670 		imsg_free(&imsg);
671 	}
672 	imsg_event_add(iev);
673 }
674 
675 int
676 proc_dispatch_null(int fd, struct privsep_proc *p, struct imsg *imsg)
677 {
678 	return (-1);
679 }
680 
681 /*
682  * imsg helper functions
683  */
684 
685 void
686 imsg_event_add(struct imsgev *iev)
687 {
688 	if (iev->handler == NULL) {
689 		imsg_flush(&iev->ibuf);
690 		return;
691 	}
692 
693 	iev->events = EV_READ;
694 	if (iev->ibuf.w.queued)
695 		iev->events |= EV_WRITE;
696 
697 	event_del(&iev->ev);
698 	event_set(&iev->ev, iev->ibuf.fd, iev->events, iev->handler, iev->data);
699 	event_add(&iev->ev, NULL);
700 }
701 
702 int
703 imsg_compose_event(struct imsgev *iev, uint16_t type, uint32_t peerid,
704     pid_t pid, int fd, void *data, uint16_t datalen)
705 {
706 	int	ret;
707 
708 	if ((ret = imsg_compose(&iev->ibuf, type, peerid,
709 	    pid, fd, data, datalen)) == -1)
710 		return (ret);
711 	imsg_event_add(iev);
712 	return (ret);
713 }
714 
715 int
716 imsg_composev_event(struct imsgev *iev, uint16_t type, uint32_t peerid,
717     pid_t pid, int fd, const struct iovec *iov, int iovcnt)
718 {
719 	int	ret;
720 
721 	if ((ret = imsg_composev(&iev->ibuf, type, peerid,
722 	    pid, fd, iov, iovcnt)) == -1)
723 		return (ret);
724 	imsg_event_add(iev);
725 	return (ret);
726 }
727 
728 void
729 proc_range(struct privsep *ps, enum privsep_procid id, int *n, int *m)
730 {
731 	if (*n == -1) {
732 		/* Use a range of all target instances */
733 		*n = 0;
734 		*m = ps->ps_instances[id];
735 	} else {
736 		/* Use only a single slot of the specified peer process */
737 		*m = *n + 1;
738 	}
739 }
740 
741 int
742 proc_compose_imsg(struct privsep *ps, enum privsep_procid id, int n,
743     uint16_t type, uint32_t peerid, int fd, void *data, uint16_t datalen)
744 {
745 	int	 m;
746 
747 	proc_range(ps, id, &n, &m);
748 	for (; n < m; n++) {
749 		if (imsg_compose_event(&ps->ps_ievs[id][n],
750 		    type, peerid, ps->ps_instance + 1, fd, data, datalen) == -1)
751 			return (-1);
752 	}
753 
754 	return (0);
755 }
756 
757 int
758 proc_compose(struct privsep *ps, enum privsep_procid id,
759     uint16_t type, void *data, uint16_t datalen)
760 {
761 	return (proc_compose_imsg(ps, id, -1, type, -1, -1, data, datalen));
762 }
763 
764 int
765 proc_composev_imsg(struct privsep *ps, enum privsep_procid id, int n,
766     uint16_t type, uint32_t peerid, int fd, const struct iovec *iov, int iovcnt)
767 {
768 	int	 m;
769 
770 	proc_range(ps, id, &n, &m);
771 	for (; n < m; n++)
772 		if (imsg_composev_event(&ps->ps_ievs[id][n],
773 		    type, peerid, ps->ps_instance + 1, fd, iov, iovcnt) == -1)
774 			return (-1);
775 
776 	return (0);
777 }
778 
779 int
780 proc_composev(struct privsep *ps, enum privsep_procid id,
781     uint16_t type, const struct iovec *iov, int iovcnt)
782 {
783 	return (proc_composev_imsg(ps, id, -1, type, -1, -1, iov, iovcnt));
784 }
785 
786 int
787 proc_forward_imsg(struct privsep *ps, struct imsg *imsg,
788     enum privsep_procid id, int n)
789 {
790 	return (proc_compose_imsg(ps, id, n, imsg->hdr.type,
791 	    imsg->hdr.peerid, imsg->fd, imsg->data, IMSG_DATA_SIZE(imsg)));
792 }
793 
794 struct imsgbuf *
795 proc_ibuf(struct privsep *ps, enum privsep_procid id, int n)
796 {
797 	int	 m;
798 
799 	proc_range(ps, id, &n, &m);
800 	return (&ps->ps_ievs[id][n].ibuf);
801 }
802 
803 struct imsgev *
804 proc_iev(struct privsep *ps, enum privsep_procid id, int n)
805 {
806 	int	 m;
807 
808 	proc_range(ps, id, &n, &m);
809 	return (&ps->ps_ievs[id][n]);
810 }
811 
812 /* This function should only be called with care as it breaks async I/O */
813 int
814 proc_flush_imsg(struct privsep *ps, enum privsep_procid id, int n)
815 {
816 	struct imsgbuf	*ibuf;
817 	int		 m, ret = 0;
818 
819 	proc_range(ps, id, &n, &m);
820 	for (; n < m; n++) {
821 		if ((ibuf = proc_ibuf(ps, id, n)) == NULL)
822 			return (-1);
823 		do {
824 			ret = imsg_flush(ibuf);
825 		} while (ret == -1 && errno == EAGAIN);
826 		if (ret == -1)
827 			break;
828 		imsg_event_add(&ps->ps_ievs[id][n]);
829 	}
830 
831 	return (ret);
832 }
833