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
send_fd(int sock,int fd)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
receive_fd(int sock)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