312 lines
6.4 KiB
C
312 lines
6.4 KiB
C
/* $OpenBSD: privsep.c,v 1.8 2004/03/14 19:17:05 otto Exp $ */
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/*
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* Copyright (c) 2003 Can Erkin Acar
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* Copyright (c) 2003 Anil Madhavapeddy <anil@recoil.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/time.h>
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#include <sys/socket.h>
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#include <net/if.h>
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#include <net/bpf.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <pwd.h>
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#include <signal.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 <pcap.h>
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#include <pcap-int.h>
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#include <syslog.h>
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#include <unistd.h>
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#include "pflogd.h"
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enum cmd_types {
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PRIV_SET_SNAPLEN, /* set the snaplength */
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PRIV_OPEN_LOG /* open logfile for appending */
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};
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static int priv_fd = -1;
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static volatile pid_t child_pid = -1;
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volatile sig_atomic_t gotsig_chld = 0;
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static void sig_pass_to_chld(int);
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static void sig_chld(int);
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static int may_read(int, void *, size_t);
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static void must_read(int, void *, size_t);
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static void must_write(int, void *, size_t);
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static int set_snaplen(int snap);
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/* bpf filter expression common to parent and child */
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extern char *filter;
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extern char *errbuf;
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extern char *filename;
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extern pcap_t *hpcap;
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/* based on syslogd privsep */
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int
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priv_init(void)
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{
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int i, fd, socks[2], cmd;
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int snaplen, ret;
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struct passwd *pw;
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#ifdef __FreeBSD__
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for (i = 1; i < NSIG; i++)
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#else
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for (i = 1; i < _NSIG; i++)
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#endif
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signal(i, SIG_DFL);
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/* Create sockets */
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if (socketpair(AF_LOCAL, SOCK_STREAM, PF_UNSPEC, socks) == -1)
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err(1, "socketpair() failed");
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pw = getpwnam("_pflogd");
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if (pw == NULL)
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errx(1, "unknown user _pflogd");
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endpwent();
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child_pid = fork();
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if (child_pid < 0)
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err(1, "fork() failed");
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if (!child_pid) {
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gid_t gidset[1];
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/* Child - drop privileges and return */
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if (chroot(pw->pw_dir) != 0)
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err(1, "unable to chroot");
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if (chdir("/") != 0)
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err(1, "unable to chdir");
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gidset[0] = pw->pw_gid;
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if (setgroups(1, gidset) == -1)
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err(1, "setgroups() failed");
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if (setegid(pw->pw_gid) == -1)
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err(1, "setegid() failed");
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if (setgid(pw->pw_gid) == -1)
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err(1, "setgid() failed");
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if (seteuid(pw->pw_uid) == -1)
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err(1, "seteuid() failed");
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if (setuid(pw->pw_uid) == -1)
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err(1, "setuid() failed");
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close(socks[0]);
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priv_fd = socks[1];
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return 0;
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}
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/* Father */
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/* Pass ALRM/TERM/HUP through to child, and accept CHLD */
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signal(SIGALRM, sig_pass_to_chld);
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signal(SIGTERM, sig_pass_to_chld);
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signal(SIGHUP, sig_pass_to_chld);
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signal(SIGCHLD, sig_chld);
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setproctitle("[priv]");
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close(socks[1]);
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while (!gotsig_chld) {
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if (may_read(socks[0], &cmd, sizeof(int)))
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break;
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switch (cmd) {
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case PRIV_SET_SNAPLEN:
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logmsg(LOG_DEBUG,
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"[priv]: msg PRIV_SET_SNAPLENGTH received");
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must_read(socks[0], &snaplen, sizeof(int));
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ret = set_snaplen(snaplen);
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if (ret) {
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logmsg(LOG_NOTICE,
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"[priv]: set_snaplen failed for snaplen %d",
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snaplen);
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}
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must_write(socks[0], &ret, sizeof(int));
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break;
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case PRIV_OPEN_LOG:
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logmsg(LOG_DEBUG,
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"[priv]: msg PRIV_OPEN_LOG received");
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/* create or append logs but do not follow symlinks */
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fd = open(filename,
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O_RDWR|O_CREAT|O_APPEND|O_NONBLOCK|O_NOFOLLOW,
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0600);
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if (fd < 0)
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logmsg(LOG_NOTICE,
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"[priv]: failed to open %s: %s",
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filename, strerror(errno));
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send_fd(socks[0], fd);
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close(fd);
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break;
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default:
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logmsg(LOG_ERR, "[priv]: unknown command %d", cmd);
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_exit(1);
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/* NOTREACHED */
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}
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}
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_exit(1);
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}
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/* this is called from parent */
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static int
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set_snaplen(int snap)
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{
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if (hpcap == NULL)
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return (1);
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hpcap->snapshot = snap;
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set_pcap_filter();
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return 0;
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}
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/*
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* send the snaplength to privileged process
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*/
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int
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priv_set_snaplen(int snaplen)
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{
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int cmd, ret;
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if (priv_fd < 0)
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errx(1, "%s: called from privileged portion", __func__);
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cmd = PRIV_SET_SNAPLEN;
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must_write(priv_fd, &cmd, sizeof(int));
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must_write(priv_fd, &snaplen, sizeof(int));
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must_read(priv_fd, &ret, sizeof(int));
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/* also set hpcap->snapshot in child */
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if (ret == 0)
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hpcap->snapshot = snaplen;
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return (ret);
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}
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/* Open log-file */
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int
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priv_open_log(void)
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{
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int cmd, fd;
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if (priv_fd < 0)
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errx(1, "%s: called from privileged portion\n", __func__);
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cmd = PRIV_OPEN_LOG;
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must_write(priv_fd, &cmd, sizeof(int));
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fd = receive_fd(priv_fd);
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return (fd);
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}
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/* If priv parent gets a TERM or HUP, pass it through to child instead */
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static void
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sig_pass_to_chld(int sig)
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{
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int oerrno = errno;
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if (child_pid != -1)
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kill(child_pid, sig);
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errno = oerrno;
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}
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/* if parent gets a SIGCHLD, it will exit */
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static void
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sig_chld(int sig)
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{
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gotsig_chld = 1;
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}
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/* Read all data or return 1 for error. */
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static int
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may_read(int fd, void *buf, size_t n)
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{
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char *s = buf;
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ssize_t res, pos = 0;
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while (n > pos) {
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res = read(fd, s + pos, n - pos);
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switch (res) {
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case -1:
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if (errno == EINTR || errno == EAGAIN)
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continue;
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case 0:
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return (1);
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default:
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pos += res;
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}
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}
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return (0);
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}
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/* Read data with the assertion that it all must come through, or
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* else abort the process. Based on atomicio() from openssh. */
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static void
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must_read(int fd, void *buf, size_t n)
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{
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char *s = buf;
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ssize_t res, pos = 0;
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while (n > pos) {
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res = read(fd, s + pos, n - pos);
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switch (res) {
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case -1:
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if (errno == EINTR || errno == EAGAIN)
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continue;
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case 0:
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_exit(0);
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default:
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pos += res;
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}
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}
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}
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/* Write data with the assertion that it all has to be written, or
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* else abort the process. Based on atomicio() from openssh. */
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static void
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must_write(int fd, void *buf, size_t n)
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{
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char *s = buf;
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ssize_t res, pos = 0;
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while (n > pos) {
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res = write(fd, s + pos, n - pos);
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switch (res) {
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case -1:
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if (errno == EINTR || errno == EAGAIN)
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continue;
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case 0:
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_exit(0);
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default:
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pos += res;
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}
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}
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}
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