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(argc, argv)
48int     argc;
49char  **argv;
50{
51    struct request_info request;
52    char    path[MAXPATHNAMELEN];
53
54    /* Attempt to prevent the creation of world-writable files. */
55
56#ifdef DAEMON_UMASK
57    umask(DAEMON_UMASK);
58#endif
59
60    /*
61     * If argv[0] is an absolute path name, ignore REAL_DAEMON_DIR, and strip
62     * argv[0] to its basename.
63     */
64
65    if (argv[0][0] == '/') {
66	strlcpy(path, argv[0], sizeof(path));
67	argv[0] = strrchr(argv[0], '/') + 1;
68    } else {
69	snprintf(path, sizeof(path), "%s/%s", REAL_DAEMON_DIR, argv[0]);
70    }
71
72    /*
73     * Open a channel to the syslog daemon. Older versions of openlog()
74     * require only two arguments.
75     */
76
77#ifdef LOG_MAIL
78    (void) openlog(argv[0], LOG_PID, FACILITY);
79#else
80    (void) openlog(argv[0], LOG_PID);
81#endif
82
83    /*
84     * Find out the endpoint addresses of this conversation. Host name
85     * lookups and double checks will be done on demand.
86     */
87
88    request_init(&request, RQ_DAEMON, argv[0], RQ_FILE, STDIN_FILENO, 0);
89    fromhost(&request);
90
91    /*
92     * Optionally look up and double check the remote host name. Sites
93     * concerned with security may choose to refuse connections from hosts
94     * that pretend to have someone elses host name.
95     */
96
97#ifdef PARANOID
98    if (STR_EQ(eval_hostname(request.client), paranoid))
99	refuse(&request);
100#endif
101
102    /*
103     * The BSD rlogin and rsh daemons that came out after 4.3 BSD disallow
104     * socket options at the IP level. They do so for a good reason.
105     * Unfortunately, we cannot use this with SunOS 4.1.x because the
106     * getsockopt() system call can panic the system.
107     */
108
109#ifdef KILL_IP_OPTIONS
110    fix_options(&request);
111#endif
112
113    /*
114     * Check whether this host can access the service in argv[0]. The
115     * access-control code invokes optional shell commands as specified in
116     * the access-control tables.
117     */
118
119#ifdef HOSTS_ACCESS
120    if (!hosts_access(&request))
121	refuse(&request);
122#endif
123
124    /* Report request and invoke the real daemon program. */
125
126#ifdef INET6
127    syslog(allow_severity, "connect from %s (%s)",
128	   eval_client(&request), eval_hostaddr(request.client));
129#else
130    syslog(allow_severity, "connect from %s", eval_client(&request));
131#endif
132    closelog();
133    (void) execv(path, argv);
134    syslog(LOG_ERR, "error: cannot execute %s: %m", path);
135    clean_exit(&request);
136    /* NOTREACHED */
137}
138