1 /*
2  * General front end for stream and datagram IP services. This program logs
3  * the remote host name and then invokes the real daemon. For example,
4  * install as /usr/etc/{tftpd,fingerd,telnetd,ftpd,rlogind,rshd,rexecd},
5  * after saving the real daemons in the directory specified with the
6  * REAL_DAEMON_DIR macro. This arrangement requires that the network daemons
7  * are started by inetd or something similar. Connections and diagnostics
8  * are logged through syslog(3).
9  *
10  * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
11  *
12  * $FreeBSD$
13  */
14
15#ifndef lint
16static char sccsid[] = "@(#) tcpd.c 1.10 96/02/11 17:01:32";
17#endif
18
19/* System libraries. */
20
21#include <sys/types.h>
22#include <sys/param.h>
23#include <sys/stat.h>
24#include <sys/socket.h>
25#include <netinet/in.h>
26#include <stdio.h>
27#include <syslog.h>
28#include <string.h>
29#include <unistd.h>
30
31#ifndef MAXPATHNAMELEN
32#define MAXPATHNAMELEN	BUFSIZ
33#endif
34
35#ifndef STDIN_FILENO
36#define STDIN_FILENO	0
37#endif
38
39/* Local stuff. */
40
41#include "patchlevel.h"
42#include "tcpd.h"
43
44int     allow_severity = SEVERITY;	/* run-time adjustable */
45int     deny_severity = LOG_WARNING;	/* ditto */
46
47main(int argc, char **argv)
48{
49    struct request_info request;
50    char    path[MAXPATHNAMELEN];
51
52    /* Attempt to prevent the creation of world-writable files. */
53
54#ifdef DAEMON_UMASK
55    umask(DAEMON_UMASK);
56#endif
57
58    /*
59     * If argv[0] is an absolute path name, ignore REAL_DAEMON_DIR, and strip
60     * argv[0] to its basename.
61     */
62
63    if (argv[0][0] == '/') {
64	strlcpy(path, argv[0], sizeof(path));
65	argv[0] = strrchr(argv[0], '/') + 1;
66    } else {
67	snprintf(path, sizeof(path), "%s/%s", REAL_DAEMON_DIR, argv[0]);
68    }
69
70    /*
71     * Open a channel to the syslog daemon. Older versions of openlog()
72     * require only two arguments.
73     */
74
75#ifdef LOG_MAIL
76    (void) openlog(argv[0], LOG_PID, FACILITY);
77#else
78    (void) openlog(argv[0], LOG_PID);
79#endif
80
81    /*
82     * Find out the endpoint addresses of this conversation. Host name
83     * lookups and double checks will be done on demand.
84     */
85
86    request_init(&request, RQ_DAEMON, argv[0], RQ_FILE, STDIN_FILENO, 0);
87    fromhost(&request);
88
89    /*
90     * Optionally look up and double check the remote host name. Sites
91     * concerned with security may choose to refuse connections from hosts
92     * that pretend to have someone elses host name.
93     */
94
95#ifdef PARANOID
96    if (STR_EQ(eval_hostname(request.client), paranoid))
97	refuse(&request);
98#endif
99
100    /*
101     * The BSD rlogin and rsh daemons that came out after 4.3 BSD disallow
102     * socket options at the IP level. They do so for a good reason.
103     * Unfortunately, we cannot use this with SunOS 4.1.x because the
104     * getsockopt() system call can panic the system.
105     */
106
107#ifdef KILL_IP_OPTIONS
108    fix_options(&request);
109#endif
110
111    /*
112     * Check whether this host can access the service in argv[0]. The
113     * access-control code invokes optional shell commands as specified in
114     * the access-control tables.
115     */
116
117#ifdef HOSTS_ACCESS
118    if (!hosts_access(&request))
119	refuse(&request);
120#endif
121
122    /* Report request and invoke the real daemon program. */
123
124#ifdef INET6
125    syslog(allow_severity, "connect from %s (%s)",
126	   eval_client(&request), eval_hostaddr(request.client));
127#else
128    syslog(allow_severity, "connect from %s", eval_client(&request));
129#endif
130    closelog();
131    (void) execv(path, argv);
132    syslog(LOG_ERR, "error: cannot execute %s: %m", path);
133    clean_exit(&request);
134    /* NOTREACHED */
135}
136