2.11BSD#431 - /usr/src/libexec/tcpd/tcpd.c

   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 1.9 94/12/28 17:42:46";
  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: main(argc, argv)
  45: int     argc;
  46: char  **argv;
  47: {
  48:     struct request_info request;
  49:     char    path[MAXPATHNAMELEN];
  50: 
  51:     /* Attempt to prevent the creation of world-writable files. */
  52: 
  53: #ifdef DAEMON_UMASK
  54:     umask(DAEMON_UMASK);
  55: #endif
  56: 
  57:     /*
  58:      * If argv[0] is an absolute path name, ignore REAL_DAEMON_DIR, and strip
  59:      * argv[0] to its basename.
  60:      */
  61: 
  62:     if (argv[0][0] == '/') {
  63:     strcpy(path, argv[0]);
  64:     argv[0] = strrchr(argv[0], '/') + 1;
  65:     } else {
  66:     sprintf(path, "%s/%s", REAL_DAEMON_DIR, argv[0]);
  67:     }
  68: 
  69:     /*
  70:      * Open a channel to the syslog daemon. Older versions of openlog()
  71:      * require only two arguments.
  72:      */
  73: 
  74: #ifdef LOG_MAIL
  75:     (void) openlog(argv[0], LOG_PID, FACILITY);
  76: #else
  77:     (void) openlog(argv[0], LOG_PID);
  78: #endif
  79: 
  80:     /*
  81:      * Find out the endpoint addresses of this conversation. Host name
  82:      * lookups and double checks will be done on demand.
  83:      */
  84: 
  85:     request_init(&request, RQ_DAEMON, argv[0], RQ_FILE, STDIN_FILENO, 0);
  86:     fromhost(&request);
  87: 
  88:     /*
  89:      * Optionally look up and double check the remote host name. Sites
  90:      * concerned with security may choose to refuse connections from hosts
  91:      * that pretend to have someone elses host name.
  92:      */
  93: 
  94: #ifdef PARANOID
  95:     if (STR_EQ(eval_hostname(request.client), paranoid))
  96:     refuse(&request);
  97: #endif
  98: 
  99:     /*
 100:      * The BSD rlogin and rsh daemons that came out after 4.3 BSD disallow
 101:      * socket options at the IP level. They do so for a good reason.
 102:      * Unfortunately, we cannot use this with SunOS 4.1.x because the
 103:      * getsockopt() system call can panic the system.
 104:      */
 105: 
 106: #ifdef KILL_IP_OPTIONS
 107:     fix_options(&request);
 108: #endif
 109: 
 110:     /*
 111:      * Check whether this host can access the service in argv[0]. The
 112:      * access-control code invokes optional shell commands as specified in
 113:      * the access-control tables.
 114:      */
 115: 
 116: #ifdef HOSTS_ACCESS
 117:     if (!hosts_access(&request))
 118:     refuse(&request);
 119: #endif
 120: 
 121:     /* Report request and invoke the real daemon program. */
 122: 
 123:     syslog(allow_severity, "connect from %s", eval_client(&request));
 124:     (void) execv(path, argv);
 125:     syslog(LOG_ERR, "error: cannot execute %s: %m", path);
 126:     clean_exit(&request);
 127:     /* NOTREACHED */
 128: }

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