1 /* $OpenBSD: privsep.c,v 1.77 2023/10/12 22:36:54 bluhm Exp $ */
2
3 /*
4 * Copyright (c) 2003 Anil Madhavapeddy <anil@recoil.org>
5 * Copyright (c) 2016 Alexander Bluhm <bluhm@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/queue.h>
21 #include <sys/stat.h>
22 #include <sys/wait.h>
23
24 #include <err.h>
25 #include <errno.h>
26 #include <fcntl.h>
27 #include <limits.h>
28 #include <netdb.h>
29 #include <paths.h>
30 #include <pwd.h>
31 #include <signal.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36 #include <utmp.h>
37
38 #include "log.h"
39 #include "syslogd.h"
40
41 /*
42 * syslogd can only go forward in these states; each state should represent
43 * less privilege. After STATE_INIT, the child is allowed to parse its
44 * config file once, and communicate the information regarding what logfiles
45 * it needs access to back to the parent. When that is done, it sends a
46 * message to the priv parent revoking this access, moving to STATE_RUNNING.
47 * In this state, any log-files not in the access list are rejected.
48 *
49 * This allows a HUP signal to the child to reopen its log files, and
50 * the config file to be parsed if it hasn't been changed (this is still
51 * useful to force resolution of remote syslog servers again).
52 * If the config file has been modified, then the child dies, and
53 * the priv parent restarts itself.
54 */
55 enum priv_state {
56 STATE_INIT, /* just started up */
57 STATE_CONFIG, /* parsing config file for first time */
58 STATE_RUNNING, /* running and accepting network traffic */
59 STATE_QUIT /* shutting down */
60 };
61
62 enum cmd_types {
63 PRIV_OPEN_TTY, /* open terminal or console device */
64 PRIV_OPEN_LOG, /* open logfile for appending */
65 PRIV_OPEN_PIPE, /* fork & exec child that gets logs on stdin */
66 PRIV_OPEN_UTMP, /* open utmp for reading only */
67 PRIV_OPEN_CONFIG, /* open config file for reading only */
68 PRIV_CONFIG_MODIFIED, /* check if config file has been modified */
69 PRIV_GETADDRINFO, /* resolve host/service names */
70 PRIV_GETNAMEINFO, /* resolve numeric address into hostname */
71 PRIV_DONE_CONFIG_PARSE /* signal that initial config parse is done */
72 };
73
74 static int priv_fd = -1;
75 static volatile pid_t child_pid = -1;
76 static volatile sig_atomic_t cur_state = STATE_INIT;
77
78 /* Queue for the allowed logfiles */
79 struct logname {
80 char path[PATH_MAX];
81 TAILQ_ENTRY(logname) next;
82 };
83 static TAILQ_HEAD(, logname) lognames;
84
85 static void check_log_name(char *, size_t);
86 static int open_file(char *);
87 static int open_pipe(char *);
88 static void check_tty_name(char *, size_t);
89 static void increase_state(int);
90 static void sig_pass_to_chld(int);
91 static void sig_got_chld(int);
92 static void must_read(int, void *, size_t);
93 static void must_write(int, void *, size_t);
94 static int may_read(int, void *, size_t);
95
96 static struct passwd *pw;
97
98 void
priv_init(int lockfd,int nullfd,int argc,char * argv[])99 priv_init(int lockfd, int nullfd, int argc, char *argv[])
100 {
101 int i, socks[2];
102 char *execpath, childnum[11], **privargv;
103
104 /* Create sockets */
105 if (socketpair(AF_LOCAL, SOCK_STREAM, PF_UNSPEC, socks) == -1)
106 err(1, "socketpair() failed");
107
108 pw = getpwnam("_syslogd");
109 if (pw == NULL)
110 errx(1, "unknown user _syslogd");
111
112 child_pid = fork();
113 if (child_pid == -1)
114 err(1, "fork() failed");
115
116 if (!child_pid) {
117 /* Child - drop privileges and return */
118 if (chroot(pw->pw_dir) != 0)
119 err(1, "chroot %s", pw->pw_dir);
120 if (chdir("/") != 0)
121 err(1, "chdir %s", pw->pw_dir);
122
123 if (setgroups(1, &pw->pw_gid) == -1)
124 err(1, "setgroups() failed");
125 if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1)
126 err(1, "setresgid() failed");
127 if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
128 err(1, "setresuid() failed");
129 close(socks[0]);
130 priv_fd = socks[1];
131 return;
132 }
133 close(socks[1]);
134
135 if (strchr(argv[0], '/') == NULL)
136 execpath = argv[0];
137 else if ((execpath = realpath(argv[0], NULL)) == NULL)
138 err(1, "realpath %s", argv[0]);
139 if (chdir("/") != 0)
140 err(1, "chdir /");
141
142 if (!Debug) {
143 close(lockfd);
144 dup2(nullfd, STDIN_FILENO);
145 dup2(nullfd, STDOUT_FILENO);
146 dup2(nullfd, STDERR_FILENO);
147 }
148 if (nullfd > 2)
149 close(nullfd);
150
151 if (dup3(socks[0], 3, 0) == -1)
152 err(1, "dup3 priv sock failed");
153 if (closefrom(4) == -1)
154 err(1, "closefrom 4 failed");
155
156 snprintf(childnum, sizeof(childnum), "%d", child_pid);
157 if ((privargv = reallocarray(NULL, argc + 3, sizeof(char *))) == NULL)
158 err(1, "alloc priv argv failed");
159 privargv[0] = execpath;
160 for (i = 1; i < argc; i++)
161 privargv[i] = argv[i];
162 privargv[i++] = "-P";
163 privargv[i++] = childnum;
164 privargv[i++] = NULL;
165 execvp(privargv[0], privargv);
166 err(1, "exec priv '%s' failed", privargv[0]);
167 }
168
169 __dead void
priv_exec(char * conf,int numeric,int child,int argc,char * argv[])170 priv_exec(char *conf, int numeric, int child, int argc, char *argv[])
171 {
172 int i, fd, sock, cmd, addr_len, result, restart;
173 size_t path_len, protoname_len, hostname_len, servname_len;
174 char path[PATH_MAX], protoname[5];
175 char hostname[NI_MAXHOST], servname[NI_MAXSERV];
176 struct sockaddr_storage addr;
177 struct stat cf_info, cf_stat;
178 struct addrinfo hints, *res0;
179 struct sigaction sa;
180 sigset_t sigmask;
181
182 /* Redo the password lookup after re-exec of the privsep parent. */
183 pw = getpwnam("_syslogd");
184 if (pw == NULL)
185 errx(1, "unknown user _syslogd");
186
187 if (unveil(conf, "r") == -1)
188 err(1, "unveil %s", conf);
189 if (unveil(_PATH_UTMP, "r") == -1)
190 err(1, "unveil %s", _PATH_UTMP);
191 if (unveil(_PATH_DEV, "rw") == -1)
192 err(1, "unveil %s", _PATH_DEV);
193 if (unveil(_PATH_LOGPID, "c") == -1)
194 err(1, "unveil %s", _PATH_LOGPID);
195
196 /* for pipes */
197 if (unveil(_PATH_BSHELL, "x") == -1)
198 err(1, "unveil %s", _PATH_BSHELL);
199
200 /* For HUP / re-exec */
201 if (unveil("/usr/sbin/syslogd", "x") == -1)
202 err(1, "unveil /usr/sbin/syslogd");
203 if (argv[0][0] == '/')
204 if (unveil(argv[0], "x") == -1)
205 err(1, "unveil %s", argv[0]);
206
207 if (pledge("stdio unveil rpath wpath cpath dns sendfd id proc exec",
208 NULL) == -1)
209 err(1, "pledge priv");
210
211 if (argc <= 2 || strcmp("-P", argv[argc - 2]) != 0)
212 errx(1, "exec without priv");
213 argv[argc -= 2] = NULL;
214
215 sock = 3;
216 closefrom(4);
217
218 child_pid = child;
219
220 memset(&sa, 0, sizeof(sa));
221 sigemptyset(&sa.sa_mask);
222 sa.sa_flags = SA_RESTART;
223 sa.sa_handler = SIG_DFL;
224 for (i = 1; i < _NSIG; i++)
225 sigaction(i, &sa, NULL);
226
227 /* Pass TERM/HUP/INT/QUIT through to child, and accept CHLD */
228 sa.sa_handler = sig_pass_to_chld;
229 sigaction(SIGTERM, &sa, NULL);
230 sigaction(SIGHUP, &sa, NULL);
231 sigaction(SIGINT, &sa, NULL);
232 sigaction(SIGQUIT, &sa, NULL);
233 sa.sa_handler = sig_got_chld;
234 sa.sa_flags |= SA_NOCLDSTOP;
235 sigaction(SIGCHLD, &sa, NULL);
236
237 setproctitle("[priv]");
238 log_debug("[priv]: fork+exec done");
239
240 sigemptyset(&sigmask);
241 if (sigprocmask(SIG_SETMASK, &sigmask, NULL) == -1)
242 err(1, "sigprocmask priv");
243
244 if (stat(conf, &cf_info) == -1)
245 err(1, "stat config file failed");
246
247 TAILQ_INIT(&lognames);
248 increase_state(STATE_CONFIG);
249 restart = 0;
250
251 while (cur_state < STATE_QUIT) {
252 if (may_read(sock, &cmd, sizeof(int)))
253 break;
254 switch (cmd) {
255 case PRIV_OPEN_TTY:
256 log_debug("[priv]: msg PRIV_OPEN_TTY received");
257 /* Expecting: length, path */
258 must_read(sock, &path_len, sizeof(size_t));
259 if (path_len == 0 || path_len > sizeof(path))
260 _exit(1);
261 must_read(sock, &path, path_len);
262 path[path_len - 1] = '\0';
263 check_tty_name(path, sizeof(path));
264 fd = open(path, O_WRONLY|O_NONBLOCK);
265 send_fd(sock, fd);
266 if (fd == -1)
267 warnx("priv_open_tty failed");
268 else
269 close(fd);
270 break;
271
272 case PRIV_OPEN_LOG:
273 case PRIV_OPEN_PIPE:
274 log_debug("[priv]: msg PRIV_OPEN_%s received",
275 cmd == PRIV_OPEN_PIPE ? "PIPE" : "LOG");
276 /* Expecting: length, path */
277 must_read(sock, &path_len, sizeof(size_t));
278 if (path_len == 0 || path_len > sizeof(path))
279 _exit(1);
280 must_read(sock, &path, path_len);
281 path[path_len - 1] = '\0';
282 check_log_name(path, sizeof(path));
283
284 if (cmd == PRIV_OPEN_LOG)
285 fd = open_file(path);
286 else if (cmd == PRIV_OPEN_PIPE)
287 fd = open_pipe(path);
288 else
289 errx(1, "invalid cmd");
290
291 send_fd(sock, fd);
292 if (fd == -1)
293 warnx("priv_open_log failed");
294 else
295 close(fd);
296 break;
297
298 case PRIV_OPEN_UTMP:
299 log_debug("[priv]: msg PRIV_OPEN_UTMP received");
300 fd = open(_PATH_UTMP, O_RDONLY|O_NONBLOCK);
301 send_fd(sock, fd);
302 if (fd == -1)
303 warnx("priv_open_utmp failed");
304 else
305 close(fd);
306 break;
307
308 case PRIV_OPEN_CONFIG:
309 log_debug("[priv]: msg PRIV_OPEN_CONFIG received");
310 stat(conf, &cf_info);
311 fd = open(conf, O_RDONLY|O_NONBLOCK);
312 send_fd(sock, fd);
313 if (fd == -1)
314 warnx("priv_open_config failed");
315 else
316 close(fd);
317 break;
318
319 case PRIV_CONFIG_MODIFIED:
320 log_debug("[priv]: msg PRIV_CONFIG_MODIFIED received");
321 if (stat(conf, &cf_stat) == -1 ||
322 timespeccmp(&cf_info.st_mtim,
323 &cf_stat.st_mtim, <) ||
324 cf_info.st_size != cf_stat.st_size) {
325 log_debug("config file modified: restarting");
326 restart = result = 1;
327 must_write(sock, &result, sizeof(int));
328 } else {
329 result = 0;
330 must_write(sock, &result, sizeof(int));
331 }
332 break;
333
334 case PRIV_DONE_CONFIG_PARSE:
335 if (pledge("stdio rpath wpath cpath dns sendfd id proc exec",
336 NULL) == -1)
337 err(1, "pledge done config");
338 log_debug("[priv]: msg PRIV_DONE_CONFIG_PARSE "
339 "received");
340 increase_state(STATE_RUNNING);
341 break;
342
343 case PRIV_GETADDRINFO:
344 log_debug("[priv]: msg PRIV_GETADDRINFO received");
345 /* Expecting: len, proto, len, host, len, serv */
346 must_read(sock, &protoname_len, sizeof(size_t));
347 if (protoname_len == 0 ||
348 protoname_len > sizeof(protoname))
349 _exit(1);
350 must_read(sock, &protoname, protoname_len);
351 protoname[protoname_len - 1] = '\0';
352
353 must_read(sock, &hostname_len, sizeof(size_t));
354 if (hostname_len == 0 ||
355 hostname_len > sizeof(hostname))
356 _exit(1);
357 must_read(sock, &hostname, hostname_len);
358 hostname[hostname_len - 1] = '\0';
359
360 must_read(sock, &servname_len, sizeof(size_t));
361 if (servname_len == 0 ||
362 servname_len > sizeof(servname))
363 _exit(1);
364 must_read(sock, &servname, servname_len);
365 servname[servname_len - 1] = '\0';
366
367 memset(&hints, 0, sizeof(hints));
368 switch (strlen(protoname)) {
369 case 3:
370 hints.ai_family = AF_UNSPEC;
371 break;
372 case 4:
373 switch (protoname[3]) {
374 case '4':
375 hints.ai_family = AF_INET;
376 break;
377 case '6':
378 hints.ai_family = AF_INET6;
379 break;
380 default:
381 errx(1, "bad ip version %s", protoname);
382 }
383 break;
384 default:
385 errx(1, "bad protocol length %s", protoname);
386 }
387 if (strncmp(protoname, "udp", 3) == 0) {
388 hints.ai_socktype = SOCK_DGRAM;
389 hints.ai_protocol = IPPROTO_UDP;
390 } else if (strncmp(protoname, "tcp", 3) == 0) {
391 hints.ai_socktype = SOCK_STREAM;
392 hints.ai_protocol = IPPROTO_TCP;
393 } else {
394 errx(1, "unknown protocol %s", protoname);
395 }
396 i = getaddrinfo(hostname, servname, &hints, &res0);
397 if (i != 0 || res0 == NULL) {
398 addr_len = 0;
399 must_write(sock, &addr_len, sizeof(int));
400 } else {
401 /* Just send the first address */
402 i = res0->ai_addrlen;
403 must_write(sock, &i, sizeof(int));
404 must_write(sock, res0->ai_addr, i);
405 freeaddrinfo(res0);
406 }
407 break;
408
409 case PRIV_GETNAMEINFO:
410 log_debug("[priv]: msg PRIV_GETNAMEINFO received");
411 if (numeric)
412 errx(1, "rejected attempt to getnameinfo");
413 /* Expecting: length, sockaddr */
414 must_read(sock, &addr_len, sizeof(int));
415 if (addr_len <= 0 || (size_t)addr_len > sizeof(addr))
416 _exit(1);
417 must_read(sock, &addr, addr_len);
418 if (getnameinfo((struct sockaddr *)&addr, addr_len,
419 hostname, sizeof(hostname), NULL, 0,
420 NI_NOFQDN|NI_NAMEREQD|NI_DGRAM) != 0) {
421 addr_len = 0;
422 must_write(sock, &addr_len, sizeof(int));
423 } else {
424 addr_len = strlen(hostname) + 1;
425 must_write(sock, &addr_len, sizeof(int));
426 must_write(sock, hostname, addr_len);
427 }
428 break;
429 default:
430 errx(1, "unknown command %d", cmd);
431 break;
432 }
433 }
434
435 close(sock);
436
437 if (restart) {
438 int status;
439
440 waitpid(child_pid, &status, 0);
441 sigemptyset(&sigmask);
442 sigaddset(&sigmask, SIGHUP);
443 if (sigprocmask(SIG_SETMASK, &sigmask, NULL) == -1)
444 err(1, "sigprocmask exec");
445 execvp(argv[0], argv);
446 err(1, "exec restart '%s' failed", argv[0]);
447 }
448 unlink(_PATH_LOGPID);
449 exit(0);
450 }
451
452 static int
open_file(char * path)453 open_file(char *path)
454 {
455 /* must not start with | */
456 if (path[0] == '|')
457 return (-1);
458
459 return (open(path, O_WRONLY|O_APPEND|O_NONBLOCK));
460 }
461
462 static int
open_pipe(char * cmd)463 open_pipe(char *cmd)
464 {
465 char *argp[] = {"sh", "-c", NULL, NULL};
466 int fd[2];
467 int bsize, flags;
468 pid_t pid;
469
470 /* skip over leading | and whitespace */
471 if (cmd[0] != '|')
472 return (-1);
473 for (cmd++; *cmd && *cmd == ' '; cmd++)
474 ; /* nothing */
475 if (!*cmd)
476 return (-1);
477
478 argp[2] = cmd;
479
480 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, fd) == -1) {
481 warnx("open_pipe");
482 return (-1);
483 }
484
485 /* make the fd on syslogd's side nonblocking */
486 if ((flags = fcntl(fd[1], F_GETFL)) == -1) {
487 warnx("fcntl");
488 return (-1);
489 }
490 flags |= O_NONBLOCK;
491 if ((flags = fcntl(fd[1], F_SETFL, flags)) == -1) {
492 warnx("fcntl");
493 return (-1);
494 }
495
496 switch (pid = fork()) {
497 case -1:
498 warnx("fork error");
499 return (-1);
500 case 0:
501 break;
502 default:
503 close(fd[0]);
504 return (fd[1]);
505 }
506
507 close(fd[1]);
508
509 /* grow receive buffer */
510 bsize = 65535;
511 while (bsize > 0 && setsockopt(fd[0], SOL_SOCKET, SO_RCVBUF,
512 &bsize, sizeof(bsize)) == -1)
513 bsize /= 2;
514
515 if (setgroups(1, &pw->pw_gid) == -1 ||
516 setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1 ||
517 setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1)
518 err(1, "failure dropping privs");
519
520 if (dup2(fd[0], STDIN_FILENO) == -1)
521 err(1, "dup2 failed");
522 closefrom(STDERR_FILENO + 1);
523 if (execv("/bin/sh", argp) == -1)
524 err(1, "execv %s", cmd);
525 /* NOTREACHED */
526 return (-1);
527 }
528
529 /* Check that the terminal device is ok, and if not, rewrite to /dev/null.
530 * Either /dev/console or /dev/tty* are allowed.
531 */
532 static void
check_tty_name(char * tty,size_t ttysize)533 check_tty_name(char *tty, size_t ttysize)
534 {
535 const char ttypre[] = "/dev/tty";
536 char *p;
537
538 /* Any path containing '..' is invalid. */
539 for (p = tty; p + 1 < tty + ttysize && *p; p++)
540 if (*p == '.' && *(p + 1) == '.')
541 goto bad_path;
542
543 if (strcmp(_PATH_CONSOLE, tty) && strncmp(tty, ttypre, strlen(ttypre)))
544 goto bad_path;
545 return;
546
547 bad_path:
548 warnx ("%s: invalid attempt to open %s: rewriting to /dev/null",
549 "check_tty_name", tty);
550 strlcpy(tty, "/dev/null", ttysize);
551 }
552
553 /* If we are in the initial configuration state, accept a logname and add
554 * it to the list of acceptable logfiles. Otherwise, check against this list
555 * and rewrite to /dev/null if it's a bad path.
556 */
557 static void
check_log_name(char * lognam,size_t logsize)558 check_log_name(char *lognam, size_t logsize)
559 {
560 struct logname *lg;
561 char *p;
562
563 /* Any path containing '..' is invalid. */
564 for (p = lognam; p + 1 < lognam + logsize && *p; p++)
565 if (*p == '.' && *(p + 1) == '.')
566 goto bad_path;
567
568 switch (cur_state) {
569 case STATE_CONFIG:
570 lg = malloc(sizeof(struct logname));
571 if (!lg)
572 err(1, "check_log_name() malloc");
573 strlcpy(lg->path, lognam, PATH_MAX);
574 TAILQ_INSERT_TAIL(&lognames, lg, next);
575 if (lognam[0] != '|') {
576 if (unveil(lognam, "w") == -1)
577 goto bad_path;
578 }
579 break;
580 case STATE_RUNNING:
581 TAILQ_FOREACH(lg, &lognames, next)
582 if (!strcmp(lg->path, lognam))
583 return;
584 goto bad_path;
585 break;
586 default:
587 /* Any other state should just refuse the request */
588 goto bad_path;
589 break;
590 }
591 return;
592
593 bad_path:
594 warnx("%s: invalid attempt to open %s: rewriting to /dev/null",
595 "check_log_name", lognam);
596 strlcpy(lognam, "/dev/null", logsize);
597 }
598
599 /* Crank our state into less permissive modes */
600 static void
increase_state(int state)601 increase_state(int state)
602 {
603 if (state <= cur_state)
604 errx(1, "attempt to decrease or match current state");
605 if (state < STATE_INIT || state > STATE_QUIT)
606 errx(1, "attempt to switch to invalid state");
607 cur_state = state;
608 }
609
610 /* Open console or a terminal device for writing */
611 int
priv_open_tty(const char * tty)612 priv_open_tty(const char *tty)
613 {
614 char path[PATH_MAX];
615 int cmd, fd;
616 size_t path_len;
617
618 if (priv_fd < 0)
619 errx(1, "%s: called from privileged portion", __func__);
620
621 if (strlcpy(path, tty, sizeof path) >= sizeof(path))
622 return -1;
623 path_len = strlen(path) + 1;
624
625 cmd = PRIV_OPEN_TTY;
626 must_write(priv_fd, &cmd, sizeof(int));
627 must_write(priv_fd, &path_len, sizeof(size_t));
628 must_write(priv_fd, path, path_len);
629 fd = receive_fd(priv_fd);
630 return fd;
631 }
632
633 /* Open log-file */
634 int
priv_open_log(const char * lognam)635 priv_open_log(const char *lognam)
636 {
637 char path[PATH_MAX];
638 int cmd, fd;
639 size_t path_len;
640
641 if (priv_fd < 0)
642 errx(1, "%s: called from privileged child", __func__);
643
644 if (strlcpy(path, lognam, sizeof path) >= sizeof(path))
645 return -1;
646 path_len = strlen(path) + 1;
647
648 if (lognam[0] == '|')
649 cmd = PRIV_OPEN_PIPE;
650 else
651 cmd = PRIV_OPEN_LOG;
652 must_write(priv_fd, &cmd, sizeof(int));
653 must_write(priv_fd, &path_len, sizeof(size_t));
654 must_write(priv_fd, path, path_len);
655 fd = receive_fd(priv_fd);
656 return fd;
657 }
658
659 /* Open utmp for reading */
660 FILE *
priv_open_utmp(void)661 priv_open_utmp(void)
662 {
663 int cmd, fd;
664 FILE *fp;
665
666 if (priv_fd < 0)
667 errx(1, "%s: called from privileged portion", __func__);
668
669 cmd = PRIV_OPEN_UTMP;
670 must_write(priv_fd, &cmd, sizeof(int));
671 fd = receive_fd(priv_fd);
672 if (fd < 0)
673 return NULL;
674
675 fp = fdopen(fd, "r");
676 if (!fp) {
677 warn("priv_open_utmp: fdopen() failed");
678 close(fd);
679 return NULL;
680 }
681
682 return fp;
683 }
684
685 /* Open syslog config file for reading */
686 FILE *
priv_open_config(void)687 priv_open_config(void)
688 {
689 int cmd, fd;
690 FILE *fp;
691
692 if (priv_fd < 0)
693 errx(1, "%s: called from privileged portion", __func__);
694
695 cmd = PRIV_OPEN_CONFIG;
696 must_write(priv_fd, &cmd, sizeof(int));
697 fd = receive_fd(priv_fd);
698 if (fd < 0)
699 return NULL;
700
701 fp = fdopen(fd, "r");
702 if (!fp) {
703 warn("priv_open_config: fdopen() failed");
704 close(fd);
705 return NULL;
706 }
707
708 return fp;
709 }
710
711 /* Ask if config file has been modified since last attempt to read it */
712 int
priv_config_modified(void)713 priv_config_modified(void)
714 {
715 int cmd, res;
716
717 if (priv_fd < 0)
718 errx(1, "%s: called from privileged portion", __func__);
719
720 cmd = PRIV_CONFIG_MODIFIED;
721 must_write(priv_fd, &cmd, sizeof(int));
722
723 /* Expect back integer signalling 1 for modification */
724 must_read(priv_fd, &res, sizeof(int));
725 return res;
726 }
727
728 /* Child can signal that its initial parsing is done, so that parent
729 * can revoke further logfile permissions. This call only works once. */
730 void
priv_config_parse_done(void)731 priv_config_parse_done(void)
732 {
733 int cmd;
734
735 if (priv_fd < 0)
736 errx(1, "%s: called from privileged portion", __func__);
737
738 cmd = PRIV_DONE_CONFIG_PARSE;
739 must_write(priv_fd, &cmd, sizeof(int));
740 }
741
742 /* Name/service to address translation. Response is placed into addr.
743 * Return 0 for success or < 0 for error like getaddrinfo(3) */
744 int
priv_getaddrinfo(const char * proto,const char * host,const char * serv,struct sockaddr * addr,size_t addr_len)745 priv_getaddrinfo(const char *proto, const char *host, const char *serv,
746 struct sockaddr *addr, size_t addr_len)
747 {
748 char protocpy[5], hostcpy[NI_MAXHOST], servcpy[NI_MAXSERV];
749 int cmd, ret_len;
750 size_t protoname_len, hostname_len, servname_len;
751
752 if (priv_fd < 0)
753 errx(1, "%s: called from privileged portion", __func__);
754
755 if (strlcpy(protocpy, proto, sizeof(protocpy)) >= sizeof(protocpy))
756 errx(1, "%s: overflow attempt in protoname", __func__);
757 protoname_len = strlen(protocpy) + 1;
758 if (strlcpy(hostcpy, host, sizeof(hostcpy)) >= sizeof(hostcpy))
759 errx(1, "%s: overflow attempt in hostname", __func__);
760 hostname_len = strlen(hostcpy) + 1;
761 if (strlcpy(servcpy, serv, sizeof(servcpy)) >= sizeof(servcpy))
762 errx(1, "%s: overflow attempt in servname", __func__);
763 servname_len = strlen(servcpy) + 1;
764
765 cmd = PRIV_GETADDRINFO;
766 must_write(priv_fd, &cmd, sizeof(int));
767 must_write(priv_fd, &protoname_len, sizeof(size_t));
768 must_write(priv_fd, protocpy, protoname_len);
769 must_write(priv_fd, &hostname_len, sizeof(size_t));
770 must_write(priv_fd, hostcpy, hostname_len);
771 must_write(priv_fd, &servname_len, sizeof(size_t));
772 must_write(priv_fd, servcpy, servname_len);
773
774 /* Expect back an integer size, and then a string of that length */
775 must_read(priv_fd, &ret_len, sizeof(int));
776
777 /* Check there was no error (indicated by a return of 0) */
778 if (!ret_len)
779 return (-1);
780
781 /* Make sure we aren't overflowing the passed in buffer */
782 if (ret_len < 0 || (size_t)ret_len > addr_len)
783 errx(1, "%s: overflow attempt in return", __func__);
784
785 /* Read the resolved address and make sure we got all of it */
786 memset(addr, '\0', addr_len);
787 must_read(priv_fd, addr, ret_len);
788
789 return (0);
790 }
791
792 /* Reverse address resolution; response is placed into host.
793 * Return 0 for success or < 0 for error like getnameinfo(3) */
794 int
priv_getnameinfo(struct sockaddr * sa,socklen_t salen,char * host,size_t hostlen)795 priv_getnameinfo(struct sockaddr *sa, socklen_t salen, char *host,
796 size_t hostlen)
797 {
798 int cmd, ret_len;
799
800 if (priv_fd < 0)
801 errx(1, "%s called from privileged portion", __func__);
802
803 cmd = PRIV_GETNAMEINFO;
804 must_write(priv_fd, &cmd, sizeof(int));
805 must_write(priv_fd, &salen, sizeof(int));
806 must_write(priv_fd, sa, salen);
807
808 /* Expect back an integer size, and then a string of that length */
809 must_read(priv_fd, &ret_len, sizeof(int));
810
811 /* Check there was no error (indicated by a return of 0) */
812 if (!ret_len)
813 return (-1);
814
815 /* Check we don't overflow the passed in buffer */
816 if (ret_len < 0 || (size_t)ret_len > hostlen)
817 errx(1, "%s: overflow attempt in return", __func__);
818
819 /* Read the resolved hostname */
820 must_read(priv_fd, host, ret_len);
821 return (0);
822 }
823
824 /* Pass the signal through to child */
825 static void
sig_pass_to_chld(int sig)826 sig_pass_to_chld(int sig)
827 {
828 int save_errno = errno;
829
830 if (child_pid != -1)
831 kill(child_pid, sig);
832 errno = save_errno;
833 }
834
835 /* When child dies, move into the shutdown state */
836 static void
sig_got_chld(int sig)837 sig_got_chld(int sig)
838 {
839 int save_errno = errno;
840 pid_t pid;
841
842 do {
843 pid = waitpid(WAIT_ANY, NULL, WNOHANG);
844 if (pid == child_pid && cur_state < STATE_QUIT)
845 cur_state = STATE_QUIT;
846 } while (pid > 0 || (pid == -1 && errno == EINTR));
847 errno = save_errno;
848 }
849
850 /* Read all data or return 1 for error. */
851 static int
may_read(int fd,void * buf,size_t n)852 may_read(int fd, void *buf, size_t n)
853 {
854 char *s = buf;
855 ssize_t res;
856 size_t pos = 0;
857
858 while (n > pos) {
859 res = read(fd, s + pos, n - pos);
860 switch (res) {
861 case -1:
862 if (errno == EINTR || errno == EAGAIN)
863 continue;
864 case 0:
865 return (1);
866 default:
867 pos += res;
868 }
869 }
870 return (0);
871 }
872
873 /* Read data with the assertion that it all must come through, or
874 * else abort the process. Based on atomicio() from openssh. */
875 static void
must_read(int fd,void * buf,size_t n)876 must_read(int fd, void *buf, size_t n)
877 {
878 char *s = buf;
879 ssize_t res;
880 size_t pos = 0;
881
882 while (n > pos) {
883 res = read(fd, s + pos, n - pos);
884 switch (res) {
885 case -1:
886 if (errno == EINTR || errno == EAGAIN)
887 continue;
888 case 0:
889 _exit(1);
890 default:
891 pos += res;
892 }
893 }
894 }
895
896 /* Write data with the assertion that it all has to be written, or
897 * else abort the process. Based on atomicio() from openssh. */
898 static void
must_write(int fd,void * buf,size_t n)899 must_write(int fd, void *buf, size_t n)
900 {
901 char *s = buf;
902 ssize_t res;
903 size_t pos = 0;
904
905 while (n > pos) {
906 res = write(fd, s + pos, n - pos);
907 switch (res) {
908 case -1:
909 if (errno == EINTR || errno == EAGAIN)
910 continue;
911 case 0:
912 _exit(1);
913 default:
914 pos += res;
915 }
916 }
917 }
918