1 /* $OpenBSD: privsep_fdpass.c,v 1.11 2015/07/09 20:16:04 bluhm Exp $ */ 2 3 /* 4 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 5 * All rights reserved. 6 * 7 * Copyright (c) 2002 Matthieu Herrb 8 * All rights reserved. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 14 * - Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * - Redistributions in binary form must reproduce the above 17 * copyright notice, this list of conditions and the following 18 * disclaimer in the documentation and/or other materials provided 19 * with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 29 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 31 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 * POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 #include <err.h> 36 #include <errno.h> 37 #include <stdio.h> 38 #include <stdlib.h> 39 #include <string.h> 40 #include <unistd.h> 41 42 #include "syslogd.h" 43 44 void 45 send_fd(int sock, int fd) 46 { 47 struct msghdr msg; 48 union { 49 struct cmsghdr hdr; 50 char buf[CMSG_SPACE(sizeof(int))]; 51 } cmsgbuf; 52 struct cmsghdr *cmsg; 53 struct iovec vec; 54 int result = 0; 55 ssize_t n; 56 57 memset(&msg, 0, sizeof(msg)); 58 59 if (fd >= 0) { 60 msg.msg_control = (caddr_t)&cmsgbuf.buf; 61 msg.msg_controllen = sizeof(cmsgbuf.buf); 62 cmsg = CMSG_FIRSTHDR(&msg); 63 cmsg->cmsg_len = CMSG_LEN(sizeof(int)); 64 cmsg->cmsg_level = SOL_SOCKET; 65 cmsg->cmsg_type = SCM_RIGHTS; 66 *(int *)CMSG_DATA(cmsg) = fd; 67 } else { 68 result = errno; 69 } 70 71 vec.iov_base = &result; 72 vec.iov_len = sizeof(int); 73 msg.msg_iov = &vec; 74 msg.msg_iovlen = 1; 75 76 if ((n = sendmsg(sock, &msg, 0)) == -1) 77 warn("%s: sendmsg(%d)", "send_fd", sock); 78 if (n != sizeof(int)) 79 warnx("%s: sendmsg: expected sent 1 got %ld", 80 "send_fd", (long)n); 81 } 82 83 int 84 receive_fd(int sock) 85 { 86 struct msghdr msg; 87 union { 88 struct cmsghdr hdr; 89 char buf[CMSG_SPACE(sizeof(int))]; 90 } cmsgbuf; 91 struct cmsghdr *cmsg; 92 struct iovec vec; 93 ssize_t n; 94 int result; 95 int fd; 96 97 memset(&msg, 0, sizeof(msg)); 98 vec.iov_base = &result; 99 vec.iov_len = sizeof(int); 100 msg.msg_iov = &vec; 101 msg.msg_iovlen = 1; 102 msg.msg_control = &cmsgbuf.buf; 103 msg.msg_controllen = sizeof(cmsgbuf.buf); 104 105 if ((n = recvmsg(sock, &msg, 0)) == -1) { 106 warn("%s: recvmsg", "receive_fd"); 107 /* receive message failed, but the result is in the socket */ 108 if (errno == EMSGSIZE) 109 recv(sock, &result, sizeof(int), MSG_DONTWAIT); 110 return -1; 111 } 112 if (n != sizeof(int)) 113 warnx("%s: recvmsg: expected received 1 got %ld", 114 "receive_fd", (long)n); 115 if (result == 0) { 116 cmsg = CMSG_FIRSTHDR(&msg); 117 if (cmsg == NULL) { 118 warnx("%s: no message header", "receive_fd"); 119 return (-1); 120 } 121 if (cmsg->cmsg_type != SCM_RIGHTS) 122 warnx("%s: expected type %d got %d", "receive_fd", 123 SCM_RIGHTS, cmsg->cmsg_type); 124 fd = (*(int *)CMSG_DATA(cmsg)); 125 return fd; 126 } else { 127 errno = result; 128 return -1; 129 } 130 } 131