IABSD.fr/src/libexec/talkd/talkd.c

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• Author : deraadt
  Date : 2019-06-28 13:32:41
  Hash : df69c215
  Message : When system calls indicate an error they return -1, not some arbitrary value < 0. errno is only updated in this case. Change all (most?) callers of syscalls to follow this better, and let's see if this strictness helps us in the future.

• libexec/talkd/talkd.c

• /*	$OpenBSD: talkd.c,v 1.26 2019/06/28 13:32:53 deraadt Exp $	*/
  
  /*
   * Copyright (c) 1983 Regents of the University of California.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  /*
   * The top level of the daemon, the format is heavily borrowed
   * from rwhod.c. Basically: find out who and where you are;
   * disconnect all descriptors and ttys, and then endless
   * loop on waiting for and processing requests
   */
  #include <sys/socket.h>
  #include <protocols/talkd.h>
  
  #include <errno.h>
  #include <limits.h>
  #include <paths.h>
  #include <signal.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <syslog.h>
  #include <unistd.h>
  
  #include "talkd.h"
  
  int	debug = 0;
  void	timeout(int);
  long	lastmsgtime;
  
  char	hostname[HOST_NAME_MAX+1];
  
  #define TIMEOUT 30
  #define MAXIDLE 120
  
  int
  main(int argc, char *argv[])
  {
  	if (getuid() != 0) {
  		fprintf(stderr, "%s: getuid: not super-user\n", argv[0]);
  		exit(1);
  	}
  	openlog("talkd", LOG_PID, LOG_DAEMON);
  	if (gethostname(hostname, sizeof(hostname)) == -1) {
  		syslog(LOG_ERR, "gethostname: %m");
  		_exit(1);
  	}
  	if (chdir(_PATH_DEV) == -1) {
  		syslog(LOG_ERR, "chdir: %s: %m", _PATH_DEV);
  		_exit(1);
  	}
  	if (argc > 1 && strcmp(argv[1], "-d") == 0)
  		debug = 1;
  	init_table();
  	signal(SIGALRM, timeout);
  	alarm(TIMEOUT);
  
  	if (pledge("stdio rpath wpath cpath inet dns", NULL) == -1) {
  		syslog(LOG_ERR, "pledge: %m");
  		_exit(1);
  	}
  
  	for (;;) {
  		CTL_RESPONSE response;
  		socklen_t len = sizeof(response.addr);
  		CTL_MSG	request;
  		int cc;
  		struct sockaddr ctl_addr;
  
  		memset(&response, 0, sizeof(response));
  		cc = recvfrom(STDIN_FILENO, (char *)&request,
  		    sizeof(request), 0, (struct sockaddr *)&response.addr,
  		    &len);
  		if (cc != sizeof(request)) {
  			if (cc == -1 && errno != EINTR)
  				syslog(LOG_WARNING, "recvfrom: %m");
  			continue;
  		}
  
  		/* Force NUL termination */
  		request.l_name[sizeof(request.l_name) - 1] = '\0';
  		request.r_name[sizeof(request.r_name) - 1] = '\0';
  		request.r_tty[sizeof(request.r_tty) - 1] = '\0';
  
  		memcpy(&ctl_addr, &request.ctl_addr, sizeof(ctl_addr));
  		ctl_addr.sa_family = ntohs(request.ctl_addr.sa_family);
  		ctl_addr.sa_len = sizeof(ctl_addr);
  		if (ctl_addr.sa_family != AF_INET)
  			continue;
  
  		lastmsgtime = time(0);
  		process_request(&request, &response);
  		/* can block here, is this what I want? */
  		cc = sendto(STDOUT_FILENO, (char *)&response,
  		    sizeof(response), 0, &ctl_addr, sizeof(ctl_addr));
  		if (cc != sizeof(response))
  			syslog(LOG_WARNING, "sendto: %m");
  	}
  }
  
  void
  timeout(int signo)
  {
  	int save_errno = errno;
  
  	if (time(0) - lastmsgtime >= MAXIDLE)
  		_exit(0);
  	alarm(TIMEOUT);
  	errno = save_errno;
  }