Adding upstream version 1:9.18.19.upstream/1%9.18.19upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 932 insertions, 0 deletions

diff --git a/bin/named/os.c b/bin/named/os.c
new file mode 100644
index 0000000..7af4729
--- /dev/null
+++ b/bin/named/os.c
@@ -0,0 +1,932 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+/*! \file */
+#include <stdarg.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/types.h> /* dev_t FreeBSD 2.1 */
+#ifdef HAVE_UNAME
+#include <sys/utsname.h>
+#endif /* ifdef HAVE_UNAME */
+
+#include <ctype.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <grp.h>
+#include <pwd.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <syslog.h>
+#ifdef HAVE_TZSET
+#include <time.h>
+#endif /* ifdef HAVE_TZSET */
+#include <unistd.h>
+
+#include <isc/buffer.h>
+#include <isc/file.h>
+#include <isc/print.h>
+#include <isc/resource.h>
+#include <isc/result.h>
+#include <isc/strerr.h>
+#include <isc/string.h>
+#include <isc/util.h>
+
+#include <named/globals.h>
+#include <named/main.h>
+#include <named/os.h>
+#ifdef HAVE_LIBSCF
+#include <named/smf_globals.h>
+#endif /* ifdef HAVE_LIBSCF */
+
+static char *pidfile = NULL;
+static char *lockfile = NULL;
+static int devnullfd = -1;
+static int singletonfd = -1;
+
+#ifndef ISC_FACILITY
+#define ISC_FACILITY LOG_DAEMON
+#endif /* ifndef ISC_FACILITY */
+
+static struct passwd *runas_pw = NULL;
+static bool done_setuid = false;
+static int dfd[2] = { -1, -1 };
+
+#ifdef HAVE_SYS_CAPABILITY_H
+
+static bool non_root = false;
+static bool non_root_caps = false;
+
+#include <sys/capability.h>
+#include <sys/prctl.h>
+
+static void
+linux_setcaps(cap_t caps) {
+	char strbuf[ISC_STRERRORSIZE];
+
+	if ((getuid() != 0 && !non_root_caps) || non_root) {
+		return;
+	}
+	if (cap_set_proc(caps) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlyfatal("cap_set_proc() failed: %s:"
+				      " please ensure that the capset kernel"
+				      " module is loaded.  see insmod(8)",
+				      strbuf);
+	}
+}
+
+#define SET_CAP(flag)                                                         \
+	do {                                                                  \
+		cap_flag_value_t curval;                                      \
+		capval = (flag);                                              \
+		err = cap_get_flag(curcaps, capval, CAP_PERMITTED, &curval);  \
+		if (err != -1 && curval) {                                    \
+			err = cap_set_flag(caps, CAP_EFFECTIVE, 1, &capval,   \
+					   CAP_SET);                          \
+			if (err == -1) {                                      \
+				strerror_r(errno, strbuf, sizeof(strbuf));    \
+				named_main_earlyfatal("cap_set_proc failed: " \
+						      "%s",                   \
+						      strbuf);                \
+			}                                                     \
+                                                                              \
+			err = cap_set_flag(caps, CAP_PERMITTED, 1, &capval,   \
+					   CAP_SET);                          \
+			if (err == -1) {                                      \
+				strerror_r(errno, strbuf, sizeof(strbuf));    \
+				named_main_earlyfatal("cap_set_proc failed: " \
+						      "%s",                   \
+						      strbuf);                \
+			}                                                     \
+		}                                                             \
+	} while (0)
+#define INIT_CAP                                                              \
+	do {                                                                  \
+		caps = cap_init();                                            \
+		if (caps == NULL) {                                           \
+			strerror_r(errno, strbuf, sizeof(strbuf));            \
+			named_main_earlyfatal("cap_init failed: %s", strbuf); \
+		}                                                             \
+		curcaps = cap_get_proc();                                     \
+		if (curcaps == NULL) {                                        \
+			strerror_r(errno, strbuf, sizeof(strbuf));            \
+			named_main_earlyfatal("cap_get_proc failed: %s",      \
+					      strbuf);                        \
+		}                                                             \
+	} while (0)
+#define FREE_CAP                   \
+	{                          \
+		cap_free(caps);    \
+		cap_free(curcaps); \
+	}                          \
+	while (0)
+
+static void
+linux_initialprivs(void) {
+	cap_t caps;
+	cap_t curcaps;
+	cap_value_t capval;
+	char strbuf[ISC_STRERRORSIZE];
+	int err;
+
+	/*%
+	 * We don't need most privileges, so we drop them right away.
+	 * Later on linux_minprivs() will be called, which will drop our
+	 * capabilities to the minimum needed to run the server.
+	 */
+	INIT_CAP;
+
+	/*
+	 * We need to be able to bind() to privileged ports, notably port 53!
+	 */
+	SET_CAP(CAP_NET_BIND_SERVICE);
+
+	/*
+	 * We need chroot() initially too.
+	 */
+	SET_CAP(CAP_SYS_CHROOT);
+
+	/*
+	 * We need setuid() as the kernel supports keeping capabilities after
+	 * setuid().
+	 */
+	SET_CAP(CAP_SETUID);
+
+	/*
+	 * Since we call initgroups, we need this.
+	 */
+	SET_CAP(CAP_SETGID);
+
+	/*
+	 * Without this, we run into problems reading a configuration file
+	 * owned by a non-root user and non-world-readable on startup.
+	 */
+	SET_CAP(CAP_DAC_READ_SEARCH);
+
+	/*
+	 * XXX  We might want to add CAP_SYS_RESOURCE, though it's not
+	 *      clear it would work right given the way linuxthreads work.
+	 * XXXDCL But since we need to be able to set the maximum number
+	 * of files, the stack size, data size, and core dump size to
+	 * support named.conf options, this is now being added to test.
+	 */
+	SET_CAP(CAP_SYS_RESOURCE);
+
+	/*
+	 * We need to be able to set the ownership of the containing
+	 * directory of the pid file when we create it.
+	 */
+	SET_CAP(CAP_CHOWN);
+
+	linux_setcaps(caps);
+
+	FREE_CAP;
+}
+
+static void
+linux_minprivs(void) {
+	cap_t caps;
+	cap_t curcaps;
+	cap_value_t capval;
+	char strbuf[ISC_STRERRORSIZE];
+	int err;
+
+	INIT_CAP;
+	/*%
+	 * Drop all privileges except the ability to bind() to privileged
+	 * ports.
+	 *
+	 * It's important that we drop CAP_SYS_CHROOT.  If we didn't, it
+	 * chroot() could be used to escape from the chrooted area.
+	 */
+
+	SET_CAP(CAP_NET_BIND_SERVICE);
+
+	/*
+	 * XXX  We might want to add CAP_SYS_RESOURCE, though it's not
+	 *      clear it would work right given the way linuxthreads work.
+	 * XXXDCL But since we need to be able to set the maximum number
+	 * of files, the stack size, data size, and core dump size to
+	 * support named.conf options, this is now being added to test.
+	 */
+	SET_CAP(CAP_SYS_RESOURCE);
+
+	linux_setcaps(caps);
+
+	FREE_CAP;
+}
+
+static void
+linux_keepcaps(void) {
+	char strbuf[ISC_STRERRORSIZE];
+	/*%
+	 * Ask the kernel to allow us to keep our capabilities after we
+	 * setuid().
+	 */
+
+	if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) < 0) {
+		if (errno != EINVAL) {
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			named_main_earlyfatal("prctl() failed: %s", strbuf);
+		}
+	} else {
+		non_root_caps = true;
+		if (getuid() != 0) {
+			non_root = true;
+		}
+	}
+}
+
+#endif /* HAVE_SYS_CAPABILITY_H */
+
+static void
+setup_syslog(const char *progname) {
+	int options;
+
+	options = LOG_PID;
+#ifdef LOG_NDELAY
+	options |= LOG_NDELAY;
+#endif /* ifdef LOG_NDELAY */
+	openlog(isc_file_basename(progname), options, ISC_FACILITY);
+}
+
+void
+named_os_init(const char *progname) {
+	setup_syslog(progname);
+#ifdef HAVE_SYS_CAPABILITY_H
+	linux_initialprivs();
+#endif /* ifdef HAVE_SYS_CAPABILITY_H */
+#ifdef SIGXFSZ
+	signal(SIGXFSZ, SIG_IGN);
+#endif /* ifdef SIGXFSZ */
+}
+
+void
+named_os_daemonize(void) {
+	pid_t pid;
+	char strbuf[ISC_STRERRORSIZE];
+
+	if (pipe(dfd) == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlyfatal("pipe(): %s", strbuf);
+	}
+
+	pid = fork();
+	if (pid == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlyfatal("fork(): %s", strbuf);
+	}
+	if (pid != 0) {
+		int n;
+		/*
+		 * Wait for the child to finish loading for the first time.
+		 * This would be so much simpler if fork() worked once we
+		 * were multi-threaded.
+		 */
+		(void)close(dfd[1]);
+		do {
+			char buf;
+			n = read(dfd[0], &buf, 1);
+			if (n == 1) {
+				_exit(0);
+			}
+		} while (n == -1 && errno == EINTR);
+		_exit(1);
+	}
+	(void)close(dfd[0]);
+
+	/*
+	 * We're the child.
+	 */
+
+	if (setsid() == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlyfatal("setsid(): %s", strbuf);
+	}
+
+	/*
+	 * Try to set stdin, stdout, and stderr to /dev/null, but press
+	 * on even if it fails.
+	 *
+	 * XXXMLG The close() calls here are unneeded on all but NetBSD, but
+	 * are harmless to include everywhere.  dup2() is supposed to close
+	 * the FD if it is in use, but unproven-pthreads-0.16 is broken
+	 * and will end up closing the wrong FD.  This will be fixed eventually,
+	 * and these calls will be removed.
+	 */
+	if (devnullfd != -1) {
+		if (devnullfd != STDIN_FILENO) {
+			(void)close(STDIN_FILENO);
+			(void)dup2(devnullfd, STDIN_FILENO);
+		}
+		if (devnullfd != STDOUT_FILENO) {
+			(void)close(STDOUT_FILENO);
+			(void)dup2(devnullfd, STDOUT_FILENO);
+		}
+		if (devnullfd != STDERR_FILENO && !named_g_keepstderr) {
+			(void)close(STDERR_FILENO);
+			(void)dup2(devnullfd, STDERR_FILENO);
+		}
+	}
+}
+
+void
+named_os_started(void) {
+	char buf = 0;
+
+	/*
+	 * Signal to the parent that we started successfully.
+	 */
+	if (dfd[0] != -1 && dfd[1] != -1) {
+		if (write(dfd[1], &buf, 1) != 1) {
+			named_main_earlyfatal("unable to signal parent that we "
+					      "otherwise started "
+					      "successfully.");
+		}
+		close(dfd[1]);
+		dfd[0] = dfd[1] = -1;
+	}
+}
+
+void
+named_os_opendevnull(void) {
+	devnullfd = open("/dev/null", O_RDWR, 0);
+}
+
+void
+named_os_closedevnull(void) {
+	if (devnullfd != STDIN_FILENO && devnullfd != STDOUT_FILENO &&
+	    devnullfd != STDERR_FILENO)
+	{
+		close(devnullfd);
+		devnullfd = -1;
+	}
+}
+
+static bool
+all_digits(const char *s) {
+	if (*s == '\0') {
+		return (false);
+	}
+	while (*s != '\0') {
+		if (!isdigit((unsigned char)(*s))) {
+			return (false);
+		}
+		s++;
+	}
+	return (true);
+}
+
+void
+named_os_chroot(const char *root) {
+	char strbuf[ISC_STRERRORSIZE];
+#ifdef HAVE_LIBSCF
+	named_smf_chroot = 0;
+#endif /* ifdef HAVE_LIBSCF */
+	if (root != NULL) {
+#ifdef HAVE_CHROOT
+		if (chroot(root) < 0) {
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			named_main_earlyfatal("chroot(): %s", strbuf);
+		}
+#else  /* ifdef HAVE_CHROOT */
+		named_main_earlyfatal("chroot(): disabled");
+#endif /* ifdef HAVE_CHROOT */
+		if (chdir("/") < 0) {
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			named_main_earlyfatal("chdir(/): %s", strbuf);
+		}
+#ifdef HAVE_LIBSCF
+		/* Set named_smf_chroot flag on successful chroot. */
+		named_smf_chroot = 1;
+#endif /* ifdef HAVE_LIBSCF */
+	}
+}
+
+void
+named_os_inituserinfo(const char *username) {
+	if (username == NULL) {
+		return;
+	}
+
+	if (all_digits(username)) {
+		runas_pw = getpwuid((uid_t)atoi(username));
+	} else {
+		runas_pw = getpwnam(username);
+	}
+	endpwent();
+
+	if (runas_pw == NULL) {
+		named_main_earlyfatal("user '%s' unknown", username);
+	}
+
+	if (getuid() == 0) {
+		char strbuf[ISC_STRERRORSIZE];
+		if (initgroups(runas_pw->pw_name, runas_pw->pw_gid) < 0) {
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			named_main_earlyfatal("initgroups(): %s", strbuf);
+		}
+	}
+}
+
+void
+named_os_changeuser(void) {
+	char strbuf[ISC_STRERRORSIZE];
+	if (runas_pw == NULL || done_setuid) {
+		return;
+	}
+
+	done_setuid = true;
+
+	if (setgid(runas_pw->pw_gid) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlyfatal("setgid(): %s", strbuf);
+	}
+
+	if (setuid(runas_pw->pw_uid) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlyfatal("setuid(): %s", strbuf);
+	}
+
+#if defined(HAVE_SYS_CAPABILITY_H)
+	/*
+	 * Restore the ability of named to drop core after the setuid()
+	 * call has disabled it.
+	 */
+	if (prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlywarning("prctl(PR_SET_DUMPABLE) failed: %s",
+					strbuf);
+	}
+
+	linux_minprivs();
+#endif /* if defined(HAVE_SYS_CAPABILITY_H) */
+}
+
+uid_t
+ns_os_uid(void) {
+	if (runas_pw == NULL) {
+		return (0);
+	}
+	return (runas_pw->pw_uid);
+}
+
+void
+named_os_adjustnofile(void) {
+#if defined(__linux__) || defined(__sun)
+	isc_result_t result;
+	isc_resourcevalue_t newvalue;
+
+	/*
+	 * Linux: max number of open files specified by one thread doesn't seem
+	 * to apply to other threads on Linux.
+	 * Sun: restriction needs to be removed sooner when hundreds of CPUs
+	 * are available.
+	 */
+	newvalue = ISC_RESOURCE_UNLIMITED;
+
+	result = isc_resource_setlimit(isc_resource_openfiles, newvalue);
+	if (result != ISC_R_SUCCESS) {
+		named_main_earlywarning("couldn't adjust limit on open files");
+	}
+#endif /* if defined(__linux__) || defined(__sun) */
+}
+
+void
+named_os_minprivs(void) {
+#if defined(HAVE_SYS_CAPABILITY_H)
+	linux_keepcaps();
+	named_os_changeuser();
+	linux_minprivs();
+#endif /* if defined(HAVE_SYS_CAPABILITY_H) */
+}
+
+static int
+safe_open(const char *filename, mode_t mode, bool append) {
+	int fd;
+	struct stat sb;
+
+	if (stat(filename, &sb) == -1) {
+		if (errno != ENOENT) {
+			return (-1);
+		}
+	} else if ((sb.st_mode & S_IFREG) == 0) {
+		errno = EOPNOTSUPP;
+		return (-1);
+	}
+
+	if (append) {
+		fd = open(filename, O_WRONLY | O_CREAT | O_APPEND, mode);
+	} else {
+		if (unlink(filename) < 0 && errno != ENOENT) {
+			return (-1);
+		}
+		fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, mode);
+	}
+	return (fd);
+}
+
+static void
+cleanup_pidfile(void) {
+	int n;
+	if (pidfile != NULL) {
+		n = unlink(pidfile);
+		if (n == -1 && errno != ENOENT) {
+			named_main_earlywarning("unlink '%s': failed", pidfile);
+		}
+		free(pidfile);
+	}
+	pidfile = NULL;
+}
+
+static void
+cleanup_lockfile(void) {
+	if (singletonfd != -1) {
+		close(singletonfd);
+		singletonfd = -1;
+	}
+
+	if (lockfile != NULL) {
+		int n = unlink(lockfile);
+		if (n == -1 && errno != ENOENT) {
+			named_main_earlywarning("unlink '%s': failed",
+						lockfile);
+		}
+		free(lockfile);
+		lockfile = NULL;
+	}
+}
+
+/*
+ * Ensure that a directory exists.
+ * NOTE: This function overwrites the '/' characters in 'filename' with
+ * nulls. The caller should copy the filename to a fresh buffer first.
+ */
+static int
+mkdirpath(char *filename, void (*report)(const char *, ...)) {
+	char *slash = strrchr(filename, '/');
+	char strbuf[ISC_STRERRORSIZE];
+	unsigned int mode;
+
+	if (slash != NULL && slash != filename) {
+		struct stat sb;
+		*slash = '\0';
+
+		if (stat(filename, &sb) == -1) {
+			if (errno != ENOENT) {
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				(*report)("couldn't stat '%s': %s", filename,
+					  strbuf);
+				goto error;
+			}
+			if (mkdirpath(filename, report) == -1) {
+				goto error;
+			}
+			/*
+			 * Handle "//", "/./" and "/../" in path.
+			 */
+			if (!strcmp(slash + 1, "") || !strcmp(slash + 1, ".") ||
+			    !strcmp(slash + 1, ".."))
+			{
+				*slash = '/';
+				return (0);
+			}
+			mode = S_IRUSR | S_IWUSR | S_IXUSR; /* u=rwx */
+			mode |= S_IRGRP | S_IXGRP;	    /* g=rx */
+			mode |= S_IROTH | S_IXOTH;	    /* o=rx */
+			if (mkdir(filename, mode) == -1) {
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				(*report)("couldn't mkdir '%s': %s", filename,
+					  strbuf);
+				goto error;
+			}
+			if (runas_pw != NULL &&
+			    chown(filename, runas_pw->pw_uid,
+				  runas_pw->pw_gid) == -1)
+			{
+				strerror_r(errno, strbuf, sizeof(strbuf));
+				(*report)("couldn't chown '%s': %s", filename,
+					  strbuf);
+			}
+		}
+		*slash = '/';
+	}
+	return (0);
+
+error:
+	*slash = '/';
+	return (-1);
+}
+
+#if !HAVE_SYS_CAPABILITY_H
+static void
+setperms(uid_t uid, gid_t gid) {
+#if defined(HAVE_SETEGID) || defined(HAVE_SETRESGID)
+	char strbuf[ISC_STRERRORSIZE];
+#endif /* if defined(HAVE_SETEGID) || defined(HAVE_SETRESGID) */
+#if !defined(HAVE_SETEGID) && defined(HAVE_SETRESGID)
+	gid_t oldgid, tmpg;
+#endif /* if !defined(HAVE_SETEGID) && defined(HAVE_SETRESGID) */
+#if !defined(HAVE_SETEUID) && defined(HAVE_SETRESUID)
+	uid_t olduid, tmpu;
+#endif /* if !defined(HAVE_SETEUID) && defined(HAVE_SETRESUID) */
+#if defined(HAVE_SETEGID)
+	if (getegid() != gid && setegid(gid) == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlywarning("unable to set effective "
+					"gid to %ld: %s",
+					(long)gid, strbuf);
+	}
+#elif defined(HAVE_SETRESGID)
+	if (getresgid(&tmpg, &oldgid, &tmpg) == -1 || oldgid != gid) {
+		if (setresgid(-1, gid, -1) == -1) {
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			named_main_earlywarning("unable to set effective "
+						"gid to %d: %s",
+						gid, strbuf);
+		}
+	}
+#endif /* if defined(HAVE_SETEGID) */
+
+#if defined(HAVE_SETEUID)
+	if (geteuid() != uid && seteuid(uid) == -1) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlywarning("unable to set effective "
+					"uid to %ld: %s",
+					(long)uid, strbuf);
+	}
+#elif defined(HAVE_SETRESUID)
+	if (getresuid(&tmpu, &olduid, &tmpu) == -1 || olduid != uid) {
+		if (setresuid(-1, uid, -1) == -1) {
+			strerror_r(errno, strbuf, sizeof(strbuf));
+			named_main_earlywarning("unable to set effective "
+						"uid to %d: %s",
+						uid, strbuf);
+		}
+	}
+#endif /* if defined(HAVE_SETEUID) */
+}
+#endif /* !HAVE_SYS_CAPABILITY_H */
+
+FILE *
+named_os_openfile(const char *filename, mode_t mode, bool switch_user) {
+	char strbuf[ISC_STRERRORSIZE], *f;
+	FILE *fp;
+	int fd;
+
+	/*
+	 * Make the containing directory if it doesn't exist.
+	 */
+	f = strdup(filename);
+	if (f == NULL) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlywarning("couldn't strdup() '%s': %s", filename,
+					strbuf);
+		return (NULL);
+	}
+	if (mkdirpath(f, named_main_earlywarning) == -1) {
+		free(f);
+		return (NULL);
+	}
+	free(f);
+
+	if (switch_user && runas_pw != NULL) {
+		uid_t olduid = getuid();
+		gid_t oldgid = getgid();
+#if HAVE_SYS_CAPABILITY_H
+		REQUIRE(olduid == runas_pw->pw_uid);
+		REQUIRE(oldgid == runas_pw->pw_gid);
+#else /* HAVE_SYS_CAPABILITY_H */
+		/* Set UID/GID to the one we'll be running with eventually */
+		setperms(runas_pw->pw_uid, runas_pw->pw_gid);
+#endif
+		fd = safe_open(filename, mode, false);
+
+#if !HAVE_SYS_CAPABILITY_H
+		/* Restore UID/GID to previous uid/gid */
+		setperms(olduid, oldgid);
+#endif
+
+		if (fd == -1) {
+			fd = safe_open(filename, mode, false);
+			if (fd != -1) {
+				named_main_earlywarning("Required root "
+							"permissions to open "
+							"'%s'.",
+							filename);
+			} else {
+				named_main_earlywarning("Could not open "
+							"'%s'.",
+							filename);
+			}
+			named_main_earlywarning("Please check file and "
+						"directory permissions "
+						"or reconfigure the filename.");
+		}
+	} else {
+		fd = safe_open(filename, mode, false);
+	}
+
+	if (fd < 0) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlywarning("could not open file '%s': %s",
+					filename, strbuf);
+		return (NULL);
+	}
+
+	fp = fdopen(fd, "w");
+	if (fp == NULL) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlywarning("could not fdopen() file '%s': %s",
+					filename, strbuf);
+	}
+
+	return (fp);
+}
+
+void
+named_os_writepidfile(const char *filename, bool first_time) {
+	FILE *fh;
+	pid_t pid;
+	char strbuf[ISC_STRERRORSIZE];
+	void (*report)(const char *, ...);
+
+	/*
+	 * The caller must ensure any required synchronization.
+	 */
+
+	report = first_time ? named_main_earlyfatal : named_main_earlywarning;
+
+	cleanup_pidfile();
+
+	if (filename == NULL) {
+		return;
+	}
+
+	pidfile = strdup(filename);
+	if (pidfile == NULL) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		(*report)("couldn't strdup() '%s': %s", filename, strbuf);
+		return;
+	}
+
+	fh = named_os_openfile(filename, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH,
+			       first_time);
+	if (fh == NULL) {
+		cleanup_pidfile();
+		return;
+	}
+	pid = getpid();
+	if (fprintf(fh, "%ld\n", (long)pid) < 0) {
+		(*report)("fprintf() to pid file '%s' failed", filename);
+		(void)fclose(fh);
+		cleanup_pidfile();
+		return;
+	}
+	if (fflush(fh) == EOF) {
+		(*report)("fflush() to pid file '%s' failed", filename);
+		(void)fclose(fh);
+		cleanup_pidfile();
+		return;
+	}
+	(void)fclose(fh);
+}
+
+bool
+named_os_issingleton(const char *filename) {
+	char strbuf[ISC_STRERRORSIZE];
+	struct flock lock;
+
+	if (singletonfd != -1) {
+		return (true);
+	}
+
+	if (strcasecmp(filename, "none") == 0) {
+		return (true);
+	}
+
+	/*
+	 * Make the containing directory if it doesn't exist.
+	 */
+	lockfile = strdup(filename);
+	if (lockfile == NULL) {
+		strerror_r(errno, strbuf, sizeof(strbuf));
+		named_main_earlyfatal("couldn't allocate memory for '%s': %s",
+				      filename, strbuf);
+	} else {
+		int ret = mkdirpath(lockfile, named_main_earlywarning);
+		if (ret == -1) {
+			named_main_earlywarning("couldn't create '%s'",
+						filename);
+			cleanup_lockfile();
+			return (false);
+		}
+	}
+
+	/*
+	 * named_os_openfile() uses safeopen() which removes any existing
+	 * files. We can't use that here.
+	 */
+	singletonfd = open(filename, O_WRONLY | O_CREAT,
+			   S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
+	if (singletonfd == -1) {
+		cleanup_lockfile();
+		return (false);
+	}
+
+	memset(&lock, 0, sizeof(lock));
+	lock.l_type = F_WRLCK;
+	lock.l_whence = SEEK_SET;
+	lock.l_start = 0;
+	lock.l_len = 1;
+
+	/* Non-blocking (does not wait for lock) */
+	if (fcntl(singletonfd, F_SETLK, &lock) == -1) {
+		close(singletonfd);
+		singletonfd = -1;
+		return (false);
+	}
+
+	return (true);
+}
+
+void
+named_os_shutdown(void) {
+	closelog();
+	cleanup_pidfile();
+	cleanup_lockfile();
+}
+
+void
+named_os_shutdownmsg(char *command, isc_buffer_t *text) {
+	char *last, *ptr;
+	pid_t pid;
+
+	/* Skip the command name. */
+	if (strtok_r(command, " \t", &last) == NULL) {
+		return;
+	}
+
+	if ((ptr = strtok_r(NULL, " \t", &last)) == NULL) {
+		return;
+	}
+
+	if (strcmp(ptr, "-p") != 0) {
+		return;
+	}
+
+	pid = getpid();
+
+	(void)isc_buffer_printf(text, "pid: %ld", (long)pid);
+}
+
+void
+named_os_tzset(void) {
+#ifdef HAVE_TZSET
+	tzset();
+#endif /* ifdef HAVE_TZSET */
+}
+
+#ifdef HAVE_UNAME
+static char unamebuf[sizeof(struct utsname)];
+#else
+static const char unamebuf[] = { "unknown architecture" };
+#endif
+static const char *unamep = NULL;
+
+static void
+getuname(void) {
+#ifdef HAVE_UNAME
+	struct utsname uts;
+
+	memset(&uts, 0, sizeof(uts));
+	if (uname(&uts) < 0) {
+		snprintf(unamebuf, sizeof(unamebuf), "unknown architecture");
+		return;
+	}
+
+	snprintf(unamebuf, sizeof(unamebuf), "%s %s %s %s", uts.sysname,
+		 uts.machine, uts.release, uts.version);
+#endif /* ifdef HAVE_UNAME */
+	unamep = unamebuf;
+}
+
+const char *
+named_os_uname(void) {
+	if (unamep == NULL) {
+		getuname();
+	}
+	return (unamep);
+}