1 /* $OpenBSD: watchdogd.c,v 1.16 2023/03/08 04:43:15 guenther Exp $ */
2
3 /*
4 * Copyright (c) 2005 Marc Balmer <mbalmer@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19 #include <sys/types.h>
20 #include <sys/resource.h>
21 #include <sys/signal.h>
22 #include <sys/sysctl.h>
23 #include <sys/mman.h>
24
25 #include <err.h>
26 #include <errno.h>
27 #include <stdio.h>
28 #include <stdlib.h>
29 #include <unistd.h>
30
31 volatile sig_atomic_t quit = 0;
32
33 __dead void usage(void);
34 void sighdlr(int);
35 int main(int, char *[]);
36
37 __dead void
usage(void)38 usage(void)
39 {
40 extern char *__progname;
41
42 fprintf(stderr, "usage: %s [-dnq] [-i interval] [-p period]\n",
43 __progname);
44 exit(1);
45 }
46
47 void
sighdlr(int signum)48 sighdlr(int signum)
49 {
50 quit = 1;
51 }
52
53 int
main(int argc,char * argv[])54 main(int argc, char *argv[])
55 {
56 struct rlimit rlim;
57 const char *errstr;
58 size_t len;
59 u_int interval = 0, period = 30, nperiod;
60 int ch, trigauto, sauto, speriod;
61 int quiet = 0, daemonize = 1, retval = 1, do_restore = 1;
62 int mib[3];
63
64 while ((ch = getopt(argc, argv, "di:np:q")) != -1) {
65 switch (ch) {
66 case 'd':
67 daemonize = 0;
68 break;
69 case 'i':
70 interval = (u_int)strtonum(optarg, 1LL, 86400LL,
71 &errstr);
72 if (errstr)
73 errx(1, "interval is %s: %s", errstr, optarg);
74 break;
75 case 'n':
76 do_restore = 0;
77 break;
78 case 'p':
79 period = (u_int)strtonum(optarg, 2LL, 86400LL, &errstr);
80 if (errstr)
81 errx(1, "period is %s: %s", errstr, optarg);
82 break;
83 case 'q':
84 quiet = 1;
85 break;
86 default:
87 usage();
88 }
89 }
90
91 argc -= optind;
92 argv += optind;
93 if (argc > 0)
94 usage();
95
96 if (interval == 0 && (interval = period / 3) == 0)
97 interval = 1;
98
99 if (period <= interval)
100 errx(1, "retrigger interval too long");
101
102 /* save kern.watchdog.period and kern.watchdog.auto for restore */
103 mib[0] = CTL_KERN;
104 mib[1] = KERN_WATCHDOG;
105 mib[2] = KERN_WATCHDOG_PERIOD;
106
107 len = sizeof(speriod);
108 if (sysctl(mib, 3, &speriod, &len, &period, sizeof(period)) == -1) {
109 if (errno == EOPNOTSUPP)
110 errx(1, "no watchdog timer available");
111 else
112 err(1, "can't access kern.watchdog.period");
113 }
114
115 mib[2] = KERN_WATCHDOG_AUTO;
116 len = sizeof(sauto);
117 trigauto = 0;
118
119 if (sysctl(mib, 3, &sauto, &len, &trigauto, sizeof(trigauto)) == -1)
120 err(1, "can't access kern.watchdog.auto");
121
122 /* Double check the timeout period, some devices change the value */
123 mib[2] = KERN_WATCHDOG_PERIOD;
124 len = sizeof(nperiod);
125 if (sysctl(mib, 3, &nperiod, &len, NULL, 0) == -1) {
126 warnx("can't read back kern.watchdog.period, "
127 "restoring original values");
128 goto restore;
129 }
130
131 if (nperiod != period && !quiet)
132 warnx("period adjusted to %d by device", nperiod);
133
134 if (nperiod <= interval) {
135 warnx("retrigger interval %d too long, "
136 "restoring original values", interval);
137 goto restore;
138 }
139
140 if (daemonize && daemon(0, 0)) {
141 warn("can't daemonize, restoring original values");
142 goto restore;
143 }
144
145 /*
146 * mlockall() below will wire the whole stack up to the limit
147 * thus we have to reduce stack size to avoid resource abuse
148 */
149 rlim.rlim_cur = 256 * 1024;
150 rlim.rlim_max = 256 * 1024;
151 (void)setrlimit(RLIMIT_STACK, &rlim);
152
153 (void)mlockall(MCL_CURRENT | MCL_FUTURE);
154 setpriority(PRIO_PROCESS, getpid(), -5);
155
156 signal(SIGTERM, sighdlr);
157
158 retval = 0;
159 while (!quit) {
160 if (sysctl(mib, 3, NULL, 0, &period, sizeof(period)) == -1)
161 quit = retval = 1;
162 sleep(interval);
163 }
164
165 if (do_restore) {
166 restore: sysctl(mib, 3, NULL, 0, &speriod, sizeof(speriod));
167 mib[2] = KERN_WATCHDOG_AUTO;
168 sysctl(mib, 3, NULL, 0, &sauto, sizeof(sauto));
169 }
170
171 return retval;
172 }
173