crypto/openssh/monitor_fdpass.c

   1 /* $OpenBSD: monitor_fdpass.c,v 1.22 2020/10/18 11:32:01 djm 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 #ifdef HAVE_SYS_UN_H
  33 #include <sys/un.h>
  34 #endif
  35
  36 #include <errno.h>
  37 #include <string.h>
  38 #include <stdarg.h>
  39
  40 #ifdef HAVE_POLL_H
  41 # include <poll.h>
  42 #else
  43 # ifdef HAVE_SYS_POLL_H
  44 #  include <sys/poll.h>
  45 # endif
  46 #endif
  47
  48 #include "log.h"
  49 #include "monitor_fdpass.h"
  50
  51 int
  52 mm_send_fd(int sock, int fd)
  53 {
  54 #if defined(HAVE_SENDMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))
  55         struct msghdr msg;
  56 #ifndef HAVE_ACCRIGHTS_IN_MSGHDR
  57         union {
  58                 struct cmsghdr hdr;
  59                 char buf[CMSG_SPACE(sizeof(int))];
  60         } cmsgbuf;
  61         struct cmsghdr *cmsg;
  62 #endif
  63         struct iovec vec;
  64         char ch = '\0';
  65         ssize_t n;
  66         struct pollfd pfd;
  67
  68         memset(&msg, 0, sizeof(msg));
  69 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
  70         msg.msg_accrights = (caddr_t)&fd;
  71         msg.msg_accrightslen = sizeof(fd);
  72 #else
  73         memset(&cmsgbuf, 0, sizeof(cmsgbuf));
  74         msg.msg_control = (caddr_t)&cmsgbuf.buf;
  75         msg.msg_controllen = sizeof(cmsgbuf.buf);
  76         cmsg = CMSG_FIRSTHDR(&msg);
  77         cmsg->cmsg_len = CMSG_LEN(sizeof(int));
  78         cmsg->cmsg_level = SOL_SOCKET;
  79         cmsg->cmsg_type = SCM_RIGHTS;
  80         *(int *)CMSG_DATA(cmsg) = fd;
  81 #endif
  82
  83         vec.iov_base = &ch;
  84         vec.iov_len = 1;
  85         msg.msg_iov = &vec;
  86         msg.msg_iovlen = 1;
  87
  88         pfd.fd = sock;
  89         pfd.events = POLLOUT;
  90         while ((n = sendmsg(sock, &msg, 0)) == -1 &&
  91             (errno == EAGAIN || errno == EINTR)) {
  92                 debug3_f("sendmsg(%d): %s", fd, strerror(errno));
  93                 (void)poll(&pfd, 1, -1);
  94         }
  95         if (n == -1) {
  96                 error_f("sendmsg(%d): %s", fd, strerror(errno));
  97                 return -1;
  98         }
  99
 100         if (n != 1) {
 101                 error_f("sendmsg: expected sent 1 got %zd", n);
 102                 return -1;
 103         }
 104         return 0;
 105 #else
 106         error("%s: file descriptor passing not supported", __func__);
 107         return -1;
 108 #endif
 109 }
 110
 111 int
 112 mm_receive_fd(int sock)
 113 {
 114 #if defined(HAVE_RECVMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))
 115         struct msghdr msg;
 116 #ifndef HAVE_ACCRIGHTS_IN_MSGHDR
 117         union {
 118                 struct cmsghdr hdr;
 119                 char buf[CMSG_SPACE(sizeof(int))];
 120         } cmsgbuf;
 121         struct cmsghdr *cmsg;
 122 #endif
 123         struct iovec vec;
 124         ssize_t n;
 125         char ch;
 126         int fd;
 127         struct pollfd pfd;
 128
 129         memset(&msg, 0, sizeof(msg));
 130         vec.iov_base = &ch;
 131         vec.iov_len = 1;
 132         msg.msg_iov = &vec;
 133         msg.msg_iovlen = 1;
 134 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
 135         msg.msg_accrights = (caddr_t)&fd;
 136         msg.msg_accrightslen = sizeof(fd);
 137 #else
 138         memset(&cmsgbuf, 0, sizeof(cmsgbuf));
 139         msg.msg_control = &cmsgbuf.buf;
 140         msg.msg_controllen = sizeof(cmsgbuf.buf);
 141 #endif
 142
 143         pfd.fd = sock;
 144         pfd.events = POLLIN;
 145         while ((n = recvmsg(sock, &msg, 0)) == -1 &&
 146             (errno == EAGAIN || errno == EINTR)) {
 147                 debug3_f("recvmsg: %s", strerror(errno));
 148                 (void)poll(&pfd, 1, -1);
 149         }
 150         if (n == -1) {
 151                 error_f("recvmsg: %s", strerror(errno));
 152                 return -1;
 153         }
 154
 155         if (n != 1) {
 156                 error_f("recvmsg: expected received 1 got %zd", n);
 157                 return -1;
 158         }
 159
 160 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
 161         if (msg.msg_accrightslen != sizeof(fd)) {
 162                 error_f("no fd");
 163                 return -1;
 164         }
 165 #else
 166         cmsg = CMSG_FIRSTHDR(&msg);
 167         if (cmsg == NULL) {
 168                 error_f("no message header");
 169                 return -1;
 170         }
 171
 172 #ifndef BROKEN_CMSG_TYPE
 173         if (cmsg->cmsg_type != SCM_RIGHTS) {
 174                 error_f("expected %d got %d", SCM_RIGHTS, cmsg->cmsg_type);
 175                 return -1;
 176         }
 177 #endif
 178         fd = (*(int *)CMSG_DATA(cmsg));
 179 #endif
 180         return fd;
 181 #else
 182         error_f("file descriptor passing not supported");
 183         return -1;
 184 #endif
 185 }