1 /* $OpenBSD: monitor_fdpass.c,v 1.23 2026/02/08 19:54:31 dtucker Exp $ */ 2 /* 3 * Copyright 2001 Niels Provos <provos@citi.umich.edu> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/uio.h> 32 #include <sys/un.h> 33 34 #include <errno.h> 35 #include <poll.h> 36 #include <string.h> 37 #include <stdarg.h> 38 39 #include "log.h" 40 #include "monitor_fdpass.h" 41 42 int 43 mm_send_fd(int sock, int fd) 44 { 45 #if defined(HAVE_SENDMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR)) 46 struct msghdr msg; 47 #ifndef HAVE_ACCRIGHTS_IN_MSGHDR 48 union { 49 struct cmsghdr hdr; 50 char buf[CMSG_SPACE(sizeof(int))]; 51 } cmsgbuf; 52 struct cmsghdr *cmsg; 53 #endif 54 struct iovec vec; 55 char ch = '\0'; 56 ssize_t n; 57 struct pollfd pfd; 58 59 memset(&msg, 0, sizeof(msg)); 60 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR 61 msg.msg_accrights = (caddr_t)&fd; 62 msg.msg_accrightslen = sizeof(fd); 63 #else 64 memset(&cmsgbuf, 0, sizeof(cmsgbuf)); 65 msg.msg_control = (caddr_t)&cmsgbuf.buf; 66 msg.msg_controllen = sizeof(cmsgbuf.buf); 67 cmsg = CMSG_FIRSTHDR(&msg); 68 cmsg->cmsg_len = CMSG_LEN(sizeof(int)); 69 cmsg->cmsg_level = SOL_SOCKET; 70 cmsg->cmsg_type = SCM_RIGHTS; 71 *(int *)CMSG_DATA(cmsg) = fd; 72 #endif 73 74 vec.iov_base = &ch; 75 vec.iov_len = 1; 76 msg.msg_iov = &vec; 77 msg.msg_iovlen = 1; 78 79 pfd.fd = sock; 80 pfd.events = POLLOUT; 81 while ((n = sendmsg(sock, &msg, 0)) == -1 && 82 (errno == EAGAIN || errno == EINTR)) { 83 debug3_f("sendmsg(%d): %s", fd, strerror(errno)); 84 (void)poll(&pfd, 1, -1); 85 } 86 if (n == -1) { 87 error_f("sendmsg(%d): %s", fd, strerror(errno)); 88 return -1; 89 } 90 91 if (n != 1) { 92 error_f("sendmsg: expected sent 1 got %zd", n); 93 return -1; 94 } 95 return 0; 96 #else 97 error_f("file descriptor passing not supported"); 98 return -1; 99 #endif 100 } 101 102 int 103 mm_receive_fd(int sock) 104 { 105 #if defined(HAVE_RECVMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR)) 106 struct msghdr msg; 107 #ifndef HAVE_ACCRIGHTS_IN_MSGHDR 108 union { 109 struct cmsghdr hdr; 110 char buf[CMSG_SPACE(sizeof(int))]; 111 } cmsgbuf; 112 struct cmsghdr *cmsg; 113 #endif 114 struct iovec vec; 115 ssize_t n; 116 char ch; 117 int fd; 118 struct pollfd pfd; 119 120 memset(&msg, 0, sizeof(msg)); 121 vec.iov_base = &ch; 122 vec.iov_len = 1; 123 msg.msg_iov = &vec; 124 msg.msg_iovlen = 1; 125 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR 126 msg.msg_accrights = (caddr_t)&fd; 127 msg.msg_accrightslen = sizeof(fd); 128 #else 129 memset(&cmsgbuf, 0, sizeof(cmsgbuf)); 130 msg.msg_control = &cmsgbuf.buf; 131 msg.msg_controllen = sizeof(cmsgbuf.buf); 132 #endif 133 134 pfd.fd = sock; 135 pfd.events = POLLIN; 136 while ((n = recvmsg(sock, &msg, 0)) == -1 && 137 (errno == EAGAIN || errno == EINTR)) { 138 debug3_f("recvmsg: %s", strerror(errno)); 139 (void)poll(&pfd, 1, -1); 140 } 141 if (n == -1) { 142 error_f("recvmsg: %s", strerror(errno)); 143 return -1; 144 } 145 146 if (n != 1) { 147 error_f("recvmsg: expected received 1 got %zd", n); 148 return -1; 149 } 150 151 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR 152 if (msg.msg_accrightslen != sizeof(fd)) { 153 error_f("no fd"); 154 return -1; 155 } 156 #else 157 cmsg = CMSG_FIRSTHDR(&msg); 158 if (cmsg == NULL) { 159 error_f("no message header"); 160 return -1; 161 } 162 163 #ifndef BROKEN_CMSG_TYPE 164 if (cmsg->cmsg_type != SCM_RIGHTS) { 165 error_f("expected %d got %d", SCM_RIGHTS, cmsg->cmsg_type); 166 return -1; 167 } 168 #endif 169 fd = (*(int *)CMSG_DATA(cmsg)); 170 #endif 171 return fd; 172 #else 173 error_f("file descriptor passing not supported"); 174 return -1; 175 #endif 176 } 177