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
13 #ifndef lint
14 static char sccsid[] = "@(#) tcpd.c 1.10 96/02/11 17:01:32";
15 #endif
16
17 /* System libraries. */
18
19 #include <sys/types.h>
20 #include <sys/param.h>
21 #include <sys/stat.h>
22 #include <sys/socket.h>
23 #include <netinet/in.h>
24 #include <stdio.h>
25 #include <syslog.h>
26 #include <string.h>
27
28 #ifndef MAXPATHNAMELEN
29 #define MAXPATHNAMELEN BUFSIZ
30 #endif
31
32 #ifndef STDIN_FILENO
33 #define STDIN_FILENO 0
34 #endif
35
36 /* Local stuff. */
37
38 #include "patchlevel.h"
39 #include "tcpd.h"
40
41 int allow_severity = SEVERITY; /* run-time adjustable */
42 int deny_severity = LOG_WARNING; /* ditto */
43
44 int
main(argc,argv)45 main(argc, argv)
46 int argc;
47 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 strcpy(path, argv[0]);
65 argv[0] = strrchr(argv[0], '/') + 1;
66 } else {
67 sprintf(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 syslog(allow_severity, "connect from %s", eval_client(&request));
125 closelog();
126 (void) execv(path, argv);
127 syslog(LOG_ERR, "error: cannot execute %s: %m", path);
128 clean_exit(&request);
129 /* NOTREACHED */
130 }
131