Move source from ndhc/ to src/ since ifchd is no longer a separate program.
This commit is contained in:
Nicholas J. Kain
406
src/ifchd.c
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406
src/ifchd.c
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@@ -0,0 +1,406 @@
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/* ifchd.c - interface change daemon
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*
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* Copyright (c) 2004-2014 Nicholas J. Kain <njkain at gmail dot com>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* - Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* - Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/epoll.h>
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#include <sys/signalfd.h>
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#include <sys/prctl.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <errno.h>
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#include <getopt.h>
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#include "nk/log.h"
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#include "nk/privilege.h"
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#include "nk/signals.h"
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#include "nk/io.h"
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#include "seccomp.h"
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#include "ifchd.h"
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#include "ndhc.h"
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#include "ifchd-parse.h"
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#include "sys.h"
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#include "ifset.h"
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struct ifchd_client cl;
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static int epollfd, signalFd;
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/* Slots are for signalFd and the ndhc -> ifchd pipe. */
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static struct epoll_event events[2];
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static int resolv_conf_fd = -1;
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/* int ntp_conf_fd = -1; */
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/* If true, allow HOSTNAME changes from dhcp server. */
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int allow_hostname = 0;
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uid_t ifch_uid = 0;
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gid_t ifch_gid = 0;
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static void writeordie(int fd, const char *buf, size_t len)
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{
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ssize_t r = safe_write(fd, buf, len);
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if (r < 0 || (size_t)r != len)
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suicide("%s: (%s) write failed: %d", client_config.interface,
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__func__, r);
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}
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/* Writes a new resolv.conf based on the information we have received. */
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static void write_resolve_conf(void)
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{
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static const char ns_str[] = "nameserver ";
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static const char dom_str[] = "domain ";
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static const char srch_str[] = "search ";
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int r;
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off_t off;
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char buf[MAX_BUF];
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if (resolv_conf_fd < 0)
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return;
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if (strlen(cl.namesvrs) == 0)
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return;
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if (lseek(resolv_conf_fd, 0, SEEK_SET) < 0)
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return;
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char *p = cl.namesvrs;
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while (p && (*p != '\0')) {
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char *q = strchr(p, ',');
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if (!q)
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q = strchr(p, '\0');
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else
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*q++ = '\0';
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ssize_t sl = snprintf(buf, sizeof buf, "%s", p);
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if (sl < 0 || (size_t)sl >= sizeof buf) {
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log_warning("%s: (%s) snprintf failed appending nameservers",
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client_config.interface, __func__);
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}
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writeordie(resolv_conf_fd, ns_str, strlen(ns_str));
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writeordie(resolv_conf_fd, buf, strlen(buf));
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writeordie(resolv_conf_fd, "\n", 1);
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p = q;
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}
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p = cl.domains;
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int numdoms = 0;
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while (p && (*p != '\0')) {
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char *q = strchr(p, ',');
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if (!q)
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q = strchr(p, '\0');
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else
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*q++ = '\0';
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ssize_t sl = snprintf(buf, sizeof buf, "%s", p);
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if (sl < 0 || (size_t)sl >= sizeof buf) {
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log_warning("%s: (%s) snprintf failed appending domains",
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client_config.interface, __func__);
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}
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if (numdoms == 0) {
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writeordie(resolv_conf_fd, dom_str, strlen(dom_str));
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writeordie(resolv_conf_fd, buf, strlen(buf));
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} else {
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if (numdoms == 1) {
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writeordie(resolv_conf_fd, "\n", 1);
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writeordie(resolv_conf_fd, srch_str, strlen(srch_str));
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writeordie(resolv_conf_fd, buf, strlen(buf));
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} else {
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writeordie(resolv_conf_fd, " ", 1);
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writeordie(resolv_conf_fd, buf, strlen(buf));
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}
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}
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++numdoms;
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p = q;
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if (numdoms > 6)
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break;
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}
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writeordie(resolv_conf_fd, "\n", 1);
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off = lseek(resolv_conf_fd, 0, SEEK_CUR);
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if (off < 0) {
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log_line("write_resolve_conf: lseek returned error: %s",
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strerror(errno));
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return;
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}
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retry:
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r = ftruncate(resolv_conf_fd, off);
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if (r < 0) {
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if (errno == EINTR)
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goto retry;
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log_line("write_resolve_conf: ftruncate returned error: %s",
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strerror(errno));
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return;
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}
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r = fsync(resolv_conf_fd);
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if (r < 0) {
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log_line("write_resolve_conf: fsync returned error: %s",
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strerror(errno));
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return;
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}
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}
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/* XXX: addme */
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void perform_timezone(const char *str, size_t len)
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{
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(void)len;
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log_line("Timezone setting NYI: '%s'", str);
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}
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/* Add a dns server to the /etc/resolv.conf -- we already have a fd. */
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void perform_dns(const char *str, size_t len)
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{
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if (!str || resolv_conf_fd < 0)
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return;
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if (len > sizeof cl.namesvrs) {
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log_line("DNS server list is too long: %zu > %zu", len, cl.namesvrs);
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return;
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}
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ssize_t sl = snprintf(cl.namesvrs, sizeof cl.namesvrs, "%s", str);
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if (sl < 0 || (size_t)sl >= sizeof cl.namesvrs) {
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log_warning("%s: (%s) snprintf failed",
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client_config.interface, __func__);
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}
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write_resolve_conf();
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log_line("Added DNS server: '%s'", str);
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}
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/* Updates for print daemons are too non-standard to be useful. */
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void perform_lprsvr(const char *str, size_t len)
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{
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(void)len;
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log_line("Line printer server setting NYI: '%s'", str);
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}
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/* Sets machine hostname. */
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void perform_hostname(const char *str, size_t len)
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{
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if (!allow_hostname || !str)
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return;
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if (sethostname(str, len) < 0)
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log_line("sethostname returned %s", strerror(errno));
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else
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log_line("Set hostname: '%s'", str);
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}
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/* update "domain" and "search" in /etc/resolv.conf */
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void perform_domain(const char *str, size_t len)
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{
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if (!str || resolv_conf_fd < 0)
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return;
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if (len > sizeof cl.domains) {
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log_line("DNS domain list is too long: %zu > %zu", len, cl.namesvrs);
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return;
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}
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ssize_t sl = snprintf(cl.domains, sizeof cl.domains, "%s", str);
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if (sl < 0 || (size_t)sl >= sizeof cl.domains) {
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log_warning("%s: (%s) snprintf failed",
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client_config.interface, __func__);
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}
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write_resolve_conf();
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log_line("Added DNS domain: '%s'", str);
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}
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/* I don't think this can be done without a netfilter extension
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* that isn't in the mainline kernels. */
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void perform_ipttl(const char *str, size_t len)
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{
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(void)len;
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log_line("TTL setting NYI: '%s'", str);
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}
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/* XXX: addme */
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void perform_ntpsrv(const char *str, size_t len)
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{
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(void)len;
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log_line("NTP server setting NYI: '%s'", str);
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}
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/* Maybe Samba cares about this feature? I don't know. */
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void perform_wins(const char *str, size_t len)
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{
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(void)str;
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(void)len;
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}
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static void setup_signals_ifch(void)
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{
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, SIGPIPE);
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sigaddset(&mask, SIGUSR1);
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sigaddset(&mask, SIGUSR2);
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sigaddset(&mask, SIGTSTP);
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sigaddset(&mask, SIGTTIN);
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sigaddset(&mask, SIGCHLD);
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sigaddset(&mask, SIGHUP);
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sigaddset(&mask, SIGINT);
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sigaddset(&mask, SIGTERM);
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if (sigprocmask(SIG_BLOCK, &mask, NULL) < 0)
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suicide("sigprocmask failed");
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signalFd = signalfd(-1, &mask, SFD_NONBLOCK);
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if (signalFd < 0)
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suicide("signalfd failed");
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}
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static void signal_dispatch(void)
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{
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int t;
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size_t off = 0;
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struct signalfd_siginfo si = {0};
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again:
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t = read(signalFd, (char *)&si + off, sizeof si - off);
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if (t < 0) {
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if (t == EAGAIN || t == EWOULDBLOCK || t == EINTR)
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goto again;
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else
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suicide("signalfd read error");
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}
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if (off + (unsigned)t < sizeof si)
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off += t;
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switch (si.ssi_signo) {
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case SIGINT:
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case SIGTERM:
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exit(EXIT_SUCCESS);
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break;
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case SIGPIPE:
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log_line("ndhc-ifch: IPC pipe closed. Exiting.");
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exit(EXIT_SUCCESS);
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break;
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default:
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break;
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}
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}
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static void inform_execute(char c)
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{
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ssize_t r = safe_write(pToNdhcW, &c, sizeof c);
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if (r == 0) {
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// Remote end hung up.
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exit(EXIT_SUCCESS);
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} else if (r < 0)
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suicide("%s: (%s) error writing to ifch -> ndhc pipe: %s",
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client_config.interface, __func__, strerror(errno));
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}
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static void process_client_pipe(void)
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{
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char buf[MAX_BUF];
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memset(buf, '\0', sizeof buf);
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ssize_t r = safe_read(pToIfchR, buf, sizeof buf - 1);
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if (r == 0) {
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// Remote end hung up.
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exit(EXIT_SUCCESS);
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} else if (r < 0) {
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if (errno == EAGAIN || errno == EWOULDBLOCK)
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return;
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suicide("%s: (%s) error reading from ndhc -> ifch pipe: %s",
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client_config.interface, __func__, strerror(errno));
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}
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if (execute_buffer(buf) < 0) {
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inform_execute('-');
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suicide("%s: (%s) received invalid commands: '%s'",
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client_config.interface, __func__, buf);
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} else
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inform_execute('+');
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}
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static void do_ifch_work(void)
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{
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epollfd = epoll_create1(0);
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if (epollfd < 0)
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suicide("epoll_create1 failed");
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if (enforce_seccomp_ifch())
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log_line("ifch seccomp filter cannot be installed");
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cl.state = STATE_NOTHING;
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memset(cl.ibuf, 0, sizeof cl.ibuf);
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memset(cl.namesvrs, 0, sizeof cl.namesvrs);
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memset(cl.domains, 0, sizeof cl.domains);
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epoll_add(epollfd, pToIfchR);
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epoll_add(epollfd, signalFd);
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for (;;) {
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int r = epoll_wait(epollfd, events, 2, -1);
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if (r < 0) {
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if (errno == EINTR)
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continue;
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else
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suicide("epoll_wait failed");
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}
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for (int i = 0; i < r; ++i) {
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int fd = events[i].data.fd;
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if (fd == pToIfchR)
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process_client_pipe();
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else if (fd == signalFd)
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signal_dispatch();
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else
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suicide("ifch: unexpected fd while performing epoll");
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}
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}
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}
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void ifch_main(void)
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{
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prctl(PR_SET_NAME, "ndhc: ifch");
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umask(077);
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setup_signals_ifch();
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// If we are requested to update resolv.conf, preopen the fd before
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// we drop root privileges, making sure that if we create
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// resolv.conf, it will be world-readable.
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if (strncmp(resolv_conf_d, "", sizeof resolv_conf_d)) {
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umask(022);
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resolv_conf_fd = open(resolv_conf_d, O_RDWR | O_CREAT, 644);
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umask(077);
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if (resolv_conf_fd < 0) {
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suicide("FATAL - unable to open resolv.conf");
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}
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}
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memset(resolv_conf_d, '\0', sizeof resolv_conf_d);
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nk_set_chroot(chroot_dir);
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memset(chroot_dir, '\0', sizeof chroot_dir);
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nk_set_uidgid(ifch_uid, ifch_gid, "cap_net_admin=ep");
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do_ifch_work();
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}
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Block a user