src/privsep_fdpass.c

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