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
39 int
mm_send_fd(int sock,int fd)40 mm_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
87 int
mm_receive_fd(int sock)88 mm_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