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
30#ifndef MAXPATHNAMELEN
31#define MAXPATHNAMELEN	BUFSIZ
32#endif
33
34#ifndef STDIN_FILENO
35#define STDIN_FILENO	0
36#endif
37
38/* Local stuff. */
39
40#include "patchlevel.h"
41#include "tcpd.h"
42
43int     allow_severity = SEVERITY;	/* run-time adjustable */
44int     deny_severity = LOG_WARNING;	/* ditto */
45
46main(argc, argv)
47int     argc;
48char  **argv;
49{
50    struct request_info request;
51    char    path[MAXPATHNAMELEN];
52
53    /* Attempt to prevent the creation of world-writable files. */
54
55#ifdef DAEMON_UMASK
56    umask(DAEMON_UMASK);
57#endif
58
59    /*
60     * If argv[0] is an absolute path name, ignore REAL_DAEMON_DIR, and strip
61     * argv[0] to its basename.
62     */
63
64    if (argv[0][0] == '/') {
65	strcpy(path, argv[0]);
66	argv[0] = strrchr(argv[0], '/') + 1;
67    } else {
68	sprintf(path, "%s/%s", REAL_DAEMON_DIR, argv[0]);
69    }
70
71    /*
72     * Open a channel to the syslog daemon. Older versions of openlog()
73     * require only two arguments.
74     */
75
76#ifdef LOG_MAIL
77    (void) openlog(argv[0], LOG_PID, FACILITY);
78#else
79    (void) openlog(argv[0], LOG_PID);
80#endif
81
82    /*
83     * Find out the endpoint addresses of this conversation. Host name
84     * lookups and double checks will be done on demand.
85     */
86
87    request_init(&request, RQ_DAEMON, argv[0], RQ_FILE, STDIN_FILENO, 0);
88    fromhost(&request);
89
90    /*
91     * Optionally look up and double check the remote host name. Sites
92     * concerned with security may choose to refuse connections from hosts
93     * that pretend to have someone elses host name.
94     */
95
96#ifdef PARANOID
97    if (STR_EQ(eval_hostname(request.client), paranoid))
98	refuse(&request);
99#endif
100
101    /*
102     * The BSD rlogin and rsh daemons that came out after 4.3 BSD disallow
103     * socket options at the IP level. They do so for a good reason.
104     * Unfortunately, we cannot use this with SunOS 4.1.x because the
105     * getsockopt() system call can panic the system.
106     */
107
108#ifdef KILL_IP_OPTIONS
109    fix_options(&request);
110#endif
111
112    /*
113     * Check whether this host can access the service in argv[0]. The
114     * access-control code invokes optional shell commands as specified in
115     * the access-control tables.
116     */
117
118#ifdef HOSTS_ACCESS
119    if (!hosts_access(&request))
120	refuse(&request);
121#endif
122
123    /* Report request and invoke the real daemon program. */
124
125#ifdef INET6
126    syslog(allow_severity, "connect from %s (%s)",
127	   eval_client(&request), eval_hostaddr(request.client));
128#else
129    syslog(allow_severity, "connect from %s", eval_client(&request));
130#endif
131    closelog();
132    (void) execv(path, argv);
133    syslog(LOG_ERR, "error: cannot execute %s: %m", path);
134    clean_exit(&request);
135    /* NOTREACHED */
136}
137