1 /*
2 * Copyright (C) 2014 - David Goulet <dgoulet@ev0ke.net>
3 *
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License, version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
11 * more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program; if not, write to the Free Software Foundation, Inc., 51
15 * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #include <assert.h>
19
20 #include <common/utils.h>
21
22 #include "torsocks.h"
23
TSOCKS_LIBC_DECL(listen,LIBC_LISTEN_RET_TYPE,LIBC_LISTEN_SIG)24 TSOCKS_LIBC_DECL(listen, LIBC_LISTEN_RET_TYPE, LIBC_LISTEN_SIG)
25
26 /*
27 * Torsocks call for listen(2).
28 */
29 LIBC_LISTEN_RET_TYPE tsocks_listen(LIBC_LISTEN_SIG)
30 {
31 int ret;
32 socklen_t addrlen;
33 struct sockaddr sa;
34
35 if (tsocks_config.allow_inbound) {
36 /* Allowed by the user so directly go to the libc. */
37 goto libc_call;
38 }
39
40 addrlen = sizeof(sa);
41
42 ret = getsockname(sockfd, &sa, &addrlen);
43 if (ret < 0) {
44 PERROR("[listen] getsockname");
45 goto error;
46 }
47
48 /*
49 * Listen () on a Unix socket is allowed else we are going to try to match
50 * it on INET localhost socket.
51 */
52 if (sa.sa_family == AF_UNIX) {
53 goto libc_call;
54 }
55
56 /* Inbound localhost connections are allowed. */
57 ret = utils_sockaddr_is_localhost(&sa);
58 if (!ret) {
59 /*
60 * Listen is completely denied here since this means that the
61 * application can accept inbound connections on non localhost that are
62 * obviously NOT handled by the Tor network thus reject this call.
63 */
64 DBG("[listen] Non localhost inbound connection are not allowed.");
65 errno = EPERM;
66 goto error;
67 }
68
69 libc_call:
70 DBG("[listen] Passing listen fd %d to libc", sockfd);
71 return tsocks_libc_listen(LIBC_LISTEN_ARGS);
72
73 error:
74 return -1;
75 }
76
77 /*
78 * Libc hijacked symbol listen(2).
79 */
80 LIBC_LISTEN_DECL
81 {
82 if (!tsocks_libc_listen) {
83 tsocks_initialize();
84 tsocks_libc_listen = tsocks_find_libc_symbol(
85 LIBC_LISTEN_NAME_STR, TSOCKS_SYM_EXIT_NOT_FOUND);
86 }
87
88 return tsocks_listen(LIBC_LISTEN_ARGS);
89 }
90