src/daemon/privsep_fdpass.c

   1 /* -*- mode: c; c-file-style: "openbsd" -*- */
   2 /*
   3  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
   4  * All rights reserved.
   5  *
   6  * Copyright (c) 2002 Matthieu Herrb
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  *
  13  *    - Redistributions of source code must retain the above copyright
  14  *      notice, this list of conditions and the following disclaimer.
  15  *    - Redistributions in binary form must reproduce the above
  16  *      copyright notice, this list of conditions and the following
  17  *      disclaimer in the documentation and/or other materials provided
  18  *      with the distribution.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  21  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  24  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  27  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  28  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  30  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 #include "lldpd.h"
  35
  36 #include <sys/param.h>
  37 #include <sys/uio.h>
  38 #include <sys/types.h>
  39 #include <sys/socket.h>
  40 #include <sys/stat.h>
  41 #include <err.h>
  42 #include <errno.h>
  43 #include <fcntl.h>
  44 #include <signal.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <unistd.h>
  49
  50 void
  51 send_fd(int sock, int fd)
  52 {
  53         struct msghdr msg;
  54         union {
  55                 struct cmsghdr hdr;
  56                 char buf[CMSG_SPACE(sizeof(int))];
  57         } cmsgbuf;
  58         struct cmsghdr *cmsg;
  59         struct iovec vec;
  60         int result = 0;
  61         ssize_t n;
  62
  63         memset(&msg, 0, sizeof(msg));
  64         memset(&cmsgbuf.buf, 0, sizeof(cmsgbuf.buf));
  65
  66         if (fd >= 0) {
  67                 msg.msg_control = (caddr_t)&cmsgbuf.buf;
  68                 msg.msg_controllen = sizeof(cmsgbuf.buf);
  69                 cmsg = CMSG_FIRSTHDR(&msg);
  70                 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
  71                 cmsg->cmsg_level = SOL_SOCKET;
  72                 cmsg->cmsg_type = SCM_RIGHTS;
  73                 memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
  74         } else {
  75                 result = errno;
  76         }
  77
  78         vec.iov_base = &result;
  79         vec.iov_len = sizeof(int);
  80         msg.msg_iov = &vec;
  81         msg.msg_iovlen = 1;
  82
  83         if ((n = sendmsg(sock, &msg, 0)) == -1)
  84                 log_warn("privsep", "sendmsg(%d)", sock);
  85         if (n != sizeof(int))
  86                 log_warnx("privsep", "sendmsg: expected sent 1 got %ld",
  87                     (long)n);
  88 }
  89
  90 int
  91 receive_fd(int sock)
  92 {
  93         struct msghdr msg;
  94         union {
  95                 struct cmsghdr hdr;
  96                 char buf[CMSG_SPACE(sizeof(int))];
  97         } cmsgbuf;
  98         struct cmsghdr *cmsg;
  99         struct iovec vec;
 100         ssize_t n;
 101         int result;
 102         int fd;
 103
 104         memset(&msg, 0, sizeof(msg));
 105         vec.iov_base = &result;
 106         vec.iov_len = sizeof(int);
 107         msg.msg_iov = &vec;
 108         msg.msg_iovlen = 1;
 109         msg.msg_control = &cmsgbuf.buf;
 110         msg.msg_controllen = sizeof(cmsgbuf.buf);
 111
 112         if ((n = recvmsg(sock, &msg, 0)) == -1)
 113                 log_warn("privsep", "recvmsg");
 114         if (n != sizeof(int))
 115                 log_warnx("privsep", "recvmsg: expected received 1 got %ld",
 116                     (long)n);
 117         if (result == 0) {
 118                 cmsg = CMSG_FIRSTHDR(&msg);
 119                 if (cmsg == NULL) {
 120                         log_warnx("privsep", "no message header");
 121                         return -1;
 122                 }
 123                 if (cmsg->cmsg_type != SCM_RIGHTS)
 124                         log_warnx("privsep", "expected type %d got %d",
 125                             SCM_RIGHTS, cmsg->cmsg_type);
 126                 memcpy(&fd, CMSG_DATA(cmsg), sizeof(int));
 127                 return fd;
 128         } else {
 129                 errno = result;
 130                 return -1;
 131         }
 132 }