1 /* $OpenBSD: privsep_fdpass.c,v 1.8 2012/04/04 17:24:50 deraadt Exp $ */
2
3 /*
4 * Copyright (c) 2002 Matthieu Herrb
5 * Copyright (c) 2001 Niels Provos <provos@citi.umich.edu>
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF MIND, USE, DATA OR PROFITS, WHETHER
16 * IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
17 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20 #include <sys/types.h>
21 #include <sys/socket.h>
22 #include <sys/uio.h>
23
24 #include <err.h>
25 #include <errno.h>
26 #include <fcntl.h>
27 #include <string.h>
28 #include <unistd.h>
29
30 #include "privsep.h"
31
32 void
send_fd(int sock,int fd)33 send_fd(int sock, int fd)
34 {
35 struct msghdr msg;
36 union {
37 struct cmsghdr hdr;
38 char buf[CMSG_SPACE(sizeof(int))];
39 } cmsgbuf;
40 struct cmsghdr *cmsg;
41 struct iovec vec;
42 int result = 0;
43 ssize_t n;
44
45 memset(&msg, 0, sizeof(msg));
46
47 if (fd >= 0) {
48 msg.msg_control = (caddr_t)&cmsgbuf.buf;
49 msg.msg_controllen = sizeof(cmsgbuf.buf);
50 cmsg = CMSG_FIRSTHDR(&msg);
51 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
52 cmsg->cmsg_level = SOL_SOCKET;
53 cmsg->cmsg_type = SCM_RIGHTS;
54 *(int *)CMSG_DATA(cmsg) = fd;
55 } else
56 result = errno;
57
58 vec.iov_base = &result;
59 vec.iov_len = sizeof(int);
60 msg.msg_iov = &vec;
61 msg.msg_iovlen = 1;
62
63 if ((n = sendmsg(sock, &msg, 0)) == -1)
64 warn("%s: sendmsg(%d)", __func__, sock);
65 if (n != sizeof(int))
66 warnx("%s: sendmsg: expected sent 1 got %ld",
67 __func__, (long)n);
68 }
69
70 int
receive_fd(int sock)71 receive_fd(int sock)
72 {
73 struct msghdr msg;
74 union {
75 struct cmsghdr hdr;
76 char buf[CMSG_SPACE(sizeof(int))];
77 } cmsgbuf;
78 struct cmsghdr *cmsg;
79 struct iovec vec;
80 ssize_t n;
81 int result;
82 int fd;
83
84 memset(&msg, 0, sizeof(msg));
85 vec.iov_base = &result;
86 vec.iov_len = sizeof(int);
87 msg.msg_iov = &vec;
88 msg.msg_iovlen = 1;
89 msg.msg_control = &cmsgbuf.buf;
90 msg.msg_controllen = sizeof(cmsgbuf.buf);
91
92 if ((n = recvmsg(sock, &msg, 0)) == -1) {
93 warn("%s: recvmsg", __func__);
94 return -1;
95 }
96 if (n != sizeof(int))
97 warnx("%s: recvmsg: expected received 1 got %ld",
98 __func__, (long)n);
99 if (result == 0) {
100 cmsg = CMSG_FIRSTHDR(&msg);
101 if (cmsg == NULL) {
102 warnx("%s: no message header", __func__);
103 return (-1);
104 }
105 if (cmsg->cmsg_type != SCM_RIGHTS)
106 warnx("%s: expected type %d got %d", __func__,
107 SCM_RIGHTS, cmsg->cmsg_type);
108 fd = (*(int *)CMSG_DATA(cmsg));
109 return (fd);
110 } else {
111 errno = result;
112 return (-1);
113 }
114 }
115