xref: /openssh-portable/monitor_fdpass.c (revision 18f64b96)
1 /* $OpenBSD: monitor_fdpass.c,v 1.21 2016/02/29 20:22:36 jca 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
mm_send_fd(int sock,int fd)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("%s: sendmsg(%d): %s", __func__, fd, strerror(errno));
93 		(void)poll(&pfd, 1, -1);
94 	}
95 	if (n == -1) {
96 		error("%s: sendmsg(%d): %s", __func__, fd,
97 		    strerror(errno));
98 		return -1;
99 	}
100 
101 	if (n != 1) {
102 		error("%s: sendmsg: expected sent 1 got %zd", __func__, n);
103 		return -1;
104 	}
105 	return 0;
106 #else
107 	error("%s: file descriptor passing not supported", __func__);
108 	return -1;
109 #endif
110 }
111 
112 int
mm_receive_fd(int sock)113 mm_receive_fd(int sock)
114 {
115 #if defined(HAVE_RECVMSG) && (defined(HAVE_ACCRIGHTS_IN_MSGHDR) || defined(HAVE_CONTROL_IN_MSGHDR))
116 	struct msghdr msg;
117 #ifndef HAVE_ACCRIGHTS_IN_MSGHDR
118 	union {
119 		struct cmsghdr hdr;
120 		char buf[CMSG_SPACE(sizeof(int))];
121 	} cmsgbuf;
122 	struct cmsghdr *cmsg;
123 #endif
124 	struct iovec vec;
125 	ssize_t n;
126 	char ch;
127 	int fd;
128 	struct pollfd pfd;
129 
130 	memset(&msg, 0, sizeof(msg));
131 	vec.iov_base = &ch;
132 	vec.iov_len = 1;
133 	msg.msg_iov = &vec;
134 	msg.msg_iovlen = 1;
135 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
136 	msg.msg_accrights = (caddr_t)&fd;
137 	msg.msg_accrightslen = sizeof(fd);
138 #else
139 	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
140 	msg.msg_control = &cmsgbuf.buf;
141 	msg.msg_controllen = sizeof(cmsgbuf.buf);
142 #endif
143 
144 	pfd.fd = sock;
145 	pfd.events = POLLIN;
146 	while ((n = recvmsg(sock, &msg, 0)) == -1 &&
147 	    (errno == EAGAIN || errno == EINTR)) {
148 		debug3("%s: recvmsg: %s", __func__, strerror(errno));
149 		(void)poll(&pfd, 1, -1);
150 	}
151 	if (n == -1) {
152 		error("%s: recvmsg: %s", __func__, strerror(errno));
153 		return -1;
154 	}
155 
156 	if (n != 1) {
157 		error("%s: recvmsg: expected received 1 got %zd", __func__, n);
158 		return -1;
159 	}
160 
161 #ifdef HAVE_ACCRIGHTS_IN_MSGHDR
162 	if (msg.msg_accrightslen != sizeof(fd)) {
163 		error("%s: no fd", __func__);
164 		return -1;
165 	}
166 #else
167 	cmsg = CMSG_FIRSTHDR(&msg);
168 	if (cmsg == NULL) {
169 		error("%s: no message header", __func__);
170 		return -1;
171 	}
172 
173 #ifndef BROKEN_CMSG_TYPE
174 	if (cmsg->cmsg_type != SCM_RIGHTS) {
175 		error("%s: expected type %d got %d", __func__,
176 		    SCM_RIGHTS, cmsg->cmsg_type);
177 		return -1;
178 	}
179 #endif
180 	fd = (*(int *)CMSG_DATA(cmsg));
181 #endif
182 	return fd;
183 #else
184 	error("%s: file descriptor passing not supported", __func__);
185 	return -1;
186 #endif
187 }
188