2 * Copyright (C) 2004-2006, 2008 Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (C) 1999-2002 Internet Software Consortium.
5 * Permission to use, copy, modify, and/or 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.
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
15 * PERFORMANCE OF THIS SOFTWARE.
18 /* $Id: os.c,v 1.66.18.17 2008/10/24 01:43:17 tbox Exp $ */
25 #include <sys/types.h> /* dev_t FreeBSD 2.1 */
31 #include <grp.h> /* Required for initgroups() on IRIX. */
42 #include <isc/buffer.h>
44 #include <isc/print.h>
45 #include <isc/resource.h>
46 #include <isc/result.h>
47 #include <isc/strerror.h>
48 #include <isc/string.h>
50 #include <named/main.h>
53 #include <named/ns_smf_globals.h>
56 static char *pidfile = NULL;
57 static int devnullfd = -1;
60 #define ISC_FACILITY LOG_DAEMON
64 * If there's no <linux/capability.h>, we don't care about <sys/prctl.h>
66 #ifndef HAVE_LINUX_CAPABILITY_H
67 #undef HAVE_SYS_PRCTL_H
72 * (T) HAVE_LINUXTHREADS
73 * (C) HAVE_LINUX_CAPABILITY_H
74 * (P) HAVE_SYS_PRCTL_H
75 * The possible cases are:
76 * none: setuid() normally
78 * C: setuid() normally, drop caps (keep CAP_SETUID)
79 * T+C: no setuid(), drop caps (don't keep CAP_SETUID)
80 * T+C+P: setuid() early, drop caps (keep CAP_SETUID)
81 * C+P: setuid() normally, drop caps (keep CAP_SETUID)
86 * caps = BIND_SERVICE + CHROOT + SETGID
87 * if ((T && C && P) || !T)
92 * if (T && C && P && -u)
99 * if (C && (P || !-u))
100 * caps = BIND_SERVICE
104 * It will be nice when Linux threads work properly with setuid().
107 #ifdef HAVE_LINUXTHREADS
108 static pid_t mainpid = 0;
111 static struct passwd *runas_pw = NULL;
112 static isc_boolean_t done_setuid = ISC_FALSE;
113 static int dfd[2] = { -1, -1 };
115 #ifdef HAVE_LINUX_CAPABILITY_H
117 static isc_boolean_t non_root = ISC_FALSE;
118 static isc_boolean_t non_root_caps = ISC_FALSE;
120 #if defined(HAVE_CAPSET)
122 #ifdef HAVE_SYS_CAPABILITY_H
123 #include <sys/capability.h>
125 #include <linux/capability.h>
126 int capset(cap_user_header_t hdrp, const cap_user_data_t datap);
128 #include <sys/prctl.h>
131 * We define _LINUX_FS_H to prevent it from being included. We don't need
132 * anything from it, and the files it includes cause warnings with 2.2
133 * kernels, and compilation failures (due to conflicts between <linux/string.h>
134 * and <string.h>) on 2.3 kernels.
138 #include <sys/syscall.h> /* Required for syscall(). */
139 #include <linux/capability.h> /* Required for _LINUX_CAPABILITY_VERSION. */
141 #ifdef HAVE_SYS_PRCTL_H
142 #include <sys/prctl.h> /* Required for prctl(). */
145 * If the value of PR_SET_KEEPCAPS is not in <sys/prctl.h>, define it
146 * here. This allows setuid() to work on systems running a new enough
147 * kernel but with /usr/include/linux pointing to "standard" kernel
150 #ifndef PR_SET_KEEPCAPS
151 #define PR_SET_KEEPCAPS 8
154 #endif /* HAVE_SYS_PRCTL_H */
158 #include <asm/unistd.h> /* Slackware 4.0 needs this. */
160 #define SYS_capset __NR_capset
165 linux_setcaps(unsigned int caps) {
166 struct __user_cap_header_struct caphead;
167 struct __user_cap_data_struct cap;
168 char strbuf[ISC_STRERRORSIZE];
170 if ((getuid() != 0 && !non_root_caps) || non_root)
173 memset(&caphead, 0, sizeof(caphead));
174 caphead.version = _LINUX_CAPABILITY_VERSION;
176 memset(&cap, 0, sizeof(cap));
177 cap.effective = caps;
178 cap.permitted = caps;
181 if (capset(&caphead, &cap) < 0 ) {
182 isc__strerror(errno, strbuf, sizeof(strbuf));
183 ns_main_earlyfatal("capset failed: %s:"
184 " please ensure that the capset kernel"
185 " module is loaded. see insmod(8)",
189 if (syscall(SYS_capset, &caphead, &cap) < 0) {
190 isc__strerror(errno, strbuf, sizeof(strbuf));
191 ns_main_earlyfatal("syscall(capset) failed: %s:"
192 " please ensure that the capset kernel"
193 " module is loaded. see insmod(8)",
200 linux_initialprivs(void) {
204 * We don't need most privileges, so we drop them right away.
205 * Later on linux_minprivs() will be called, which will drop our
206 * capabilities to the minimum needed to run the server.
212 * We need to be able to bind() to privileged ports, notably port 53!
214 caps |= (1 << CAP_NET_BIND_SERVICE);
217 * We need chroot() initially too.
219 caps |= (1 << CAP_SYS_CHROOT);
221 #if defined(HAVE_SYS_PRCTL_H) || !defined(HAVE_LINUXTHREADS)
223 * We can setuid() only if either the kernel supports keeping
224 * capabilities after setuid() (which we don't know until we've
225 * tried) or we're not using threads. If either of these is
226 * true, we want the setuid capability.
228 caps |= (1 << CAP_SETUID);
232 * Since we call initgroups, we need this.
234 caps |= (1 << CAP_SETGID);
237 * Without this, we run into problems reading a configuration file
238 * owned by a non-root user and non-world-readable on startup.
240 caps |= (1 << CAP_DAC_READ_SEARCH);
243 * XXX We might want to add CAP_SYS_RESOURCE, though it's not
244 * clear it would work right given the way linuxthreads work.
245 * XXXDCL But since we need to be able to set the maximum number
246 * of files, the stack size, data size, and core dump size to
247 * support named.conf options, this is now being added to test.
249 caps |= (1 << CAP_SYS_RESOURCE);
255 linux_minprivs(void) {
259 * Drop all privileges except the ability to bind() to privileged
262 * It's important that we drop CAP_SYS_CHROOT. If we didn't, it
263 * chroot() could be used to escape from the chrooted area.
267 caps |= (1 << CAP_NET_BIND_SERVICE);
270 * XXX We might want to add CAP_SYS_RESOURCE, though it's not
271 * clear it would work right given the way linuxthreads work.
272 * XXXDCL But since we need to be able to set the maximum number
273 * of files, the stack size, data size, and core dump size to
274 * support named.conf options, this is now being added to test.
276 caps |= (1 << CAP_SYS_RESOURCE);
281 #ifdef HAVE_SYS_PRCTL_H
283 linux_keepcaps(void) {
284 char strbuf[ISC_STRERRORSIZE];
286 * Ask the kernel to allow us to keep our capabilities after we
290 if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) < 0) {
291 if (errno != EINVAL) {
292 isc__strerror(errno, strbuf, sizeof(strbuf));
293 ns_main_earlyfatal("prctl() failed: %s", strbuf);
296 non_root_caps = ISC_TRUE;
303 #endif /* HAVE_LINUX_CAPABILITY_H */
307 setup_syslog(const char *progname) {
312 options |= LOG_NDELAY;
314 openlog(isc_file_basename(progname), options, ISC_FACILITY);
318 ns_os_init(const char *progname) {
319 setup_syslog(progname);
320 #ifdef HAVE_LINUX_CAPABILITY_H
321 linux_initialprivs();
323 #ifdef HAVE_LINUXTHREADS
327 signal(SIGXFSZ, SIG_IGN);
332 ns_os_daemonize(void) {
334 char strbuf[ISC_STRERRORSIZE];
336 if (pipe(dfd) == -1) {
337 isc__strerror(errno, strbuf, sizeof(strbuf));
338 ns_main_earlyfatal("pipe(): %s", strbuf);
343 isc__strerror(errno, strbuf, sizeof(strbuf));
344 ns_main_earlyfatal("fork(): %s", strbuf);
349 * Wait for the child to finish loading for the first time.
350 * This would be so much simpler if fork() worked once we
351 * were multi-threaded.
356 n = read(dfd[0], &buf, 1);
359 } while (n == -1 && errno == EINTR);
368 #ifdef HAVE_LINUXTHREADS
372 if (setsid() == -1) {
373 isc__strerror(errno, strbuf, sizeof(strbuf));
374 ns_main_earlyfatal("setsid(): %s", strbuf);
378 * Try to set stdin, stdout, and stderr to /dev/null, but press
379 * on even if it fails.
381 * XXXMLG The close() calls here are unneeded on all but NetBSD, but
382 * are harmless to include everywhere. dup2() is supposed to close
383 * the FD if it is in use, but unproven-pthreads-0.16 is broken
384 * and will end up closing the wrong FD. This will be fixed eventually,
385 * and these calls will be removed.
387 if (devnullfd != -1) {
388 if (devnullfd != STDIN_FILENO) {
389 (void)close(STDIN_FILENO);
390 (void)dup2(devnullfd, STDIN_FILENO);
392 if (devnullfd != STDOUT_FILENO) {
393 (void)close(STDOUT_FILENO);
394 (void)dup2(devnullfd, STDOUT_FILENO);
396 if (devnullfd != STDERR_FILENO) {
397 (void)close(STDERR_FILENO);
398 (void)dup2(devnullfd, STDERR_FILENO);
404 ns_os_started(void) {
408 * Signal to the parent that we stated successfully.
410 if (dfd[0] != -1 && dfd[1] != -1) {
411 write(dfd[1], &buf, 1);
413 dfd[0] = dfd[1] = -1;
418 ns_os_opendevnull(void) {
419 devnullfd = open("/dev/null", O_RDWR, 0);
423 ns_os_closedevnull(void) {
424 if (devnullfd != STDIN_FILENO &&
425 devnullfd != STDOUT_FILENO &&
426 devnullfd != STDERR_FILENO) {
433 all_digits(const char *s) {
437 if (!isdigit((*s)&0xff))
445 ns_os_chroot(const char *root) {
446 char strbuf[ISC_STRERRORSIZE];
451 if (chroot(root) < 0) {
452 isc__strerror(errno, strbuf, sizeof(strbuf));
453 ns_main_earlyfatal("chroot(): %s", strbuf);
455 if (chdir("/") < 0) {
456 isc__strerror(errno, strbuf, sizeof(strbuf));
457 ns_main_earlyfatal("chdir(/): %s", strbuf);
460 /* Set ns_smf_chroot flag on successful chroot. */
467 ns_os_inituserinfo(const char *username) {
468 char strbuf[ISC_STRERRORSIZE];
469 if (username == NULL)
472 if (all_digits(username))
473 runas_pw = getpwuid((uid_t)atoi(username));
475 runas_pw = getpwnam(username);
478 if (runas_pw == NULL)
479 ns_main_earlyfatal("user '%s' unknown", username);
482 if (initgroups(runas_pw->pw_name, runas_pw->pw_gid) < 0) {
483 isc__strerror(errno, strbuf, sizeof(strbuf));
484 ns_main_earlyfatal("initgroups(): %s", strbuf);
491 ns_os_changeuser(void) {
492 char strbuf[ISC_STRERRORSIZE];
493 if (runas_pw == NULL || done_setuid)
496 done_setuid = ISC_TRUE;
498 #ifdef HAVE_LINUXTHREADS
499 #ifdef HAVE_LINUX_CAPABILITY_H
501 ns_main_earlyfatal("-u with Linux threads not supported: "
502 "requires kernel support for "
503 "prctl(PR_SET_KEEPCAPS)");
505 ns_main_earlyfatal("-u with Linux threads not supported: "
506 "no capabilities support or capabilities "
507 "disabled at build time");
511 if (setgid(runas_pw->pw_gid) < 0) {
512 isc__strerror(errno, strbuf, sizeof(strbuf));
513 ns_main_earlyfatal("setgid(): %s", strbuf);
516 if (setuid(runas_pw->pw_uid) < 0) {
517 isc__strerror(errno, strbuf, sizeof(strbuf));
518 ns_main_earlyfatal("setuid(): %s", strbuf);
521 #if defined(HAVE_SYS_PRCTL_H) && defined(PR_SET_DUMPABLE)
523 * Restore the ability of named to drop core after the setuid()
524 * call has disabled it.
526 if (prctl(PR_SET_DUMPABLE,1,0,0,0) < 0) {
527 isc__strerror(errno, strbuf, sizeof(strbuf));
528 ns_main_earlywarning("prctl(PR_SET_DUMPABLE) failed: %s",
532 #if defined(HAVE_LINUX_CAPABILITY_H) && !defined(HAVE_LINUXTHREADS)
538 ns_os_adjustnofile() {
539 #ifdef HAVE_LINUXTHREADS
541 isc_resourcevalue_t newvalue;
544 * Linux: max number of open files specified by one thread doesn't seem
545 * to apply to other threads on Linux.
547 newvalue = ISC_RESOURCE_UNLIMITED;
549 result = isc_resource_setlimit(isc_resource_openfiles, newvalue);
550 if (result != ISC_R_SUCCESS)
551 ns_main_earlywarning("couldn't adjust limit on open files");
556 ns_os_minprivs(void) {
557 #ifdef HAVE_SYS_PRCTL_H
561 #ifdef HAVE_LINUXTHREADS
562 ns_os_changeuser(); /* Call setuid() before threads are started */
565 #if defined(HAVE_LINUX_CAPABILITY_H) && defined(HAVE_LINUXTHREADS)
571 safe_open(const char *filename, isc_boolean_t append) {
575 if (stat(filename, &sb) == -1) {
578 } else if ((sb.st_mode & S_IFREG) == 0) {
584 fd = open(filename, O_WRONLY|O_CREAT|O_APPEND,
585 S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
587 (void)unlink(filename);
588 fd = open(filename, O_WRONLY|O_CREAT|O_EXCL,
589 S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
595 cleanup_pidfile(void) {
596 if (pidfile != NULL) {
597 (void)unlink(pidfile);
604 ns_os_writepidfile(const char *filename, isc_boolean_t first_time) {
609 char strbuf[ISC_STRERRORSIZE];
610 void (*report)(const char *, ...);
613 * The caller must ensure any required synchronization.
616 report = first_time ? ns_main_earlyfatal : ns_main_earlywarning;
620 if (filename == NULL)
623 len = strlen(filename);
624 pidfile = malloc(len + 1);
625 if (pidfile == NULL) {
626 isc__strerror(errno, strbuf, sizeof(strbuf));
627 (*report)("couldn't malloc '%s': %s", filename, strbuf);
631 strcpy(pidfile, filename);
633 fd = safe_open(filename, ISC_FALSE);
635 isc__strerror(errno, strbuf, sizeof(strbuf));
636 (*report)("couldn't open pid file '%s': %s", filename, strbuf);
641 lockfile = fdopen(fd, "w");
642 if (lockfile == NULL) {
643 isc__strerror(errno, strbuf, sizeof(strbuf));
644 (*report)("could not fdopen() pid file '%s': %s",
650 #ifdef HAVE_LINUXTHREADS
655 if (fprintf(lockfile, "%ld\n", (long)pid) < 0) {
656 (*report)("fprintf() to pid file '%s' failed", filename);
657 (void)fclose(lockfile);
661 if (fflush(lockfile) == EOF) {
662 (*report)("fflush() to pid file '%s' failed", filename);
663 (void)fclose(lockfile);
667 (void)fclose(lockfile);
671 ns_os_shutdown(void) {
677 ns_os_gethostname(char *buf, size_t len) {
680 n = gethostname(buf, len);
681 return ((n == 0) ? ISC_R_SUCCESS : ISC_R_FAILURE);
685 next_token(char **stringp, const char *delim) {
689 res = strsep(stringp, delim);
692 } while (*res == '\0');
697 ns_os_shutdownmsg(char *command, isc_buffer_t *text) {
704 /* Skip the command name. */
705 ptr = next_token(&input, " \t");
709 ptr = next_token(&input, " \t");
713 if (strcmp(ptr, "-p") != 0)
716 #ifdef HAVE_LINUXTHREADS
722 n = snprintf((char *)isc_buffer_used(text),
723 isc_buffer_availablelength(text),
724 "pid: %ld", (long)pid);
725 /* Only send a message if it is complete. */
726 if (n < isc_buffer_availablelength(text))
727 isc_buffer_add(text, n);