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 <sys/types.h>
28#include <sys/socket.h>
29#include <sys/uio.h>
30
31#include <errno.h>
32#include <poll.h>
33#include <string.h>
34#include <stdarg.h>
35
36#include "log.h"
37#include "monitor_fdpass.h"
38
39int
40mm_send_fd(int sock, int fd)
41{
42	struct msghdr msg;
43	union {
44		struct cmsghdr hdr;
45		char buf[CMSG_SPACE(sizeof(int))];
46	} cmsgbuf;
47	struct cmsghdr *cmsg;
48	struct iovec vec;
49	char ch = '\0';
50	ssize_t n;
51	struct pollfd pfd;
52
53	memset(&msg, 0, sizeof(msg));
54	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
55	msg.msg_control = (caddr_t)&cmsgbuf.buf;
56	msg.msg_controllen = sizeof(cmsgbuf.buf);
57	cmsg = CMSG_FIRSTHDR(&msg);
58	cmsg->cmsg_len = CMSG_LEN(sizeof(int));
59	cmsg->cmsg_level = SOL_SOCKET;
60	cmsg->cmsg_type = SCM_RIGHTS;
61	*(int *)CMSG_DATA(cmsg) = fd;
62
63	vec.iov_base = &ch;
64	vec.iov_len = 1;
65	msg.msg_iov = &vec;
66	msg.msg_iovlen = 1;
67
68	pfd.fd = sock;
69	pfd.events = POLLOUT;
70	while ((n = sendmsg(sock, &msg, 0)) == -1 &&
71	    (errno == EAGAIN || errno == EINTR)) {
72		debug3_f("sendmsg(%d): %s", fd, strerror(errno));
73		(void)poll(&pfd, 1, -1);
74	}
75	if (n == -1) {
76		error_f("sendmsg(%d): %s", fd, strerror(errno));
77		return -1;
78	}
79
80	if (n != 1) {
81		error_f("sendmsg: expected sent 1 got %zd", n);
82		return -1;
83	}
84	return 0;
85}
86
87int
88mm_receive_fd(int sock)
89{
90	struct msghdr msg;
91	union {
92		struct cmsghdr hdr;
93		char buf[CMSG_SPACE(sizeof(int))];
94	} cmsgbuf;
95	struct cmsghdr *cmsg;
96	struct iovec vec;
97	ssize_t n;
98	char ch;
99	int fd;
100	struct pollfd pfd;
101
102	memset(&msg, 0, sizeof(msg));
103	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
104	vec.iov_base = &ch;
105	vec.iov_len = 1;
106	msg.msg_iov = &vec;
107	msg.msg_iovlen = 1;
108	msg.msg_control = &cmsgbuf.buf;
109	msg.msg_controllen = sizeof(cmsgbuf.buf);
110
111	pfd.fd = sock;
112	pfd.events = POLLIN;
113	while ((n = recvmsg(sock, &msg, 0)) == -1 &&
114	    (errno == EAGAIN || errno == EINTR)) {
115		debug3_f("recvmsg: %s", strerror(errno));
116		(void)poll(&pfd, 1, -1);
117	}
118	if (n == -1) {
119		error_f("recvmsg: %s", strerror(errno));
120		return -1;
121	}
122
123	if (n != 1) {
124		error_f("recvmsg: expected received 1 got %zd", n);
125		return -1;
126	}
127
128	cmsg = CMSG_FIRSTHDR(&msg);
129	if (cmsg == NULL) {
130		error_f("no message header");
131		return -1;
132	}
133
134	if (cmsg->cmsg_type != SCM_RIGHTS) {
135		error_f("expected %d got %d", SCM_RIGHTS, cmsg->cmsg_type);
136		return -1;
137	}
138	fd = (*(int *)CMSG_DATA(cmsg));
139	return fd;
140}
141