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tcpdchk.c

 /*
  * tcpdchk - examine all tcpd access control rules and inetd.conf entries
  * 
  * Usage: tcpdchk [-a] [-d] [-i inet_conf] [-v]
  * 
  * -a: complain about implicit "allow" at end of rule.
  * 
  * -d: rules in current directory.
  * 
  * -i: location of inetd.conf file.
  * 
  * -v: show all rules.
  * 
  * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
  */

#ifndef lint
static char sccsid[] = "@(#) tcpdchk.c 1.8 97/02/12 02:13:25";
#endif

/* System libraries. */

#include <sys/types.h>
#include <sys/stat.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <syslog.h>
#include <setjmp.h>
#include <errno.h>
#include <netdb.h>
#include <string.h>

extern int errno;
extern void exit();
extern int optind;
extern char *optarg;

#ifndef INADDR_NONE
#define INADDR_NONE     (-1)        /* XXX should be 0xffffffff */
#endif

#ifndef S_ISDIR
#define S_ISDIR(m)      (((m) & S_IFMT) == S_IFDIR)
#endif

/* Application-specific. */

#include "tcpd.h"
#include "inetcf.h"
#include "scaffold.h"

 /*
  * Stolen from hosts_access.c...
  */
static char sep[] = ", \t\n";

#define     BUFLEN 2048

int     resident = 0;
int     hosts_access_verbose = 0;
char   *hosts_allow_table = HOSTS_ALLOW;
char   *hosts_deny_table = HOSTS_DENY;
extern jmp_buf tcpd_buf;

 /*
  * Local stuff.
  */
static void usage();
static void parse_table();
static void print_list();
static void check_daemon_list();
static void check_client_list();
static void check_daemon();
static void check_user();
static int check_host();
static int reserved_name();

#define PERMIT    1
#define DENY      0

#define YES 1
#define     NO    0

static int defl_verdict;
static char *myname;
static int allow_check;
static char *inetcf;

int     main(argc, argv)
int     argc;
char  **argv;
{
    struct request_info request;
    struct stat st;
    int     c;

    myname = argv[0];

    /*
     * Parse the JCL.
     */
    while ((c = getopt(argc, argv, "adi:v")) != EOF) {
      switch (c) {
      case 'a':
          allow_check = 1;
          break;
      case 'd':
          hosts_allow_table = "hosts.allow";
          hosts_deny_table = "hosts.deny";
          break;
      case 'i':
          inetcf = optarg;
          break;
      case 'v':
          hosts_access_verbose++;
          break;
      default:
          usage();
          /* NOTREACHED */
      }
    }
    if (argc != optind)
      usage();

    /*
     * When confusion really strikes...
     */
    if (check_path(REAL_DAEMON_DIR, &st) < 0) {
      tcpd_warn("REAL_DAEMON_DIR %s: %m", REAL_DAEMON_DIR);
    } else if (!S_ISDIR(st.st_mode)) {
      tcpd_warn("REAL_DAEMON_DIR %s is not a directory", REAL_DAEMON_DIR);
    }

    /*
     * Process the inet configuration file (or its moral equivalent). This
     * information is used later to find references in hosts.allow/deny to
     * unwrapped services, and other possible problems.
     */
    inetcf = inet_cfg(inetcf);
    if (hosts_access_verbose)
      printf("Using network configuration file: %s\n", inetcf);

    /*
     * These are not run from inetd but may have built-in access control.
     */
    inet_set("portmap", WR_NOT);
    inet_set("rpcbind", WR_NOT);

    /*
     * Check accessibility of access control files.
     */
    (void) check_path(hosts_allow_table, &st);
    (void) check_path(hosts_deny_table, &st);

    /*
     * Fake up an arbitrary service request.
     */
    request_init(&request,
             RQ_DAEMON, "daemon_name",
             RQ_SERVER_NAME, "server_hostname",
             RQ_SERVER_ADDR, "server_addr",
             RQ_USER, "user_name",
             RQ_CLIENT_NAME, "client_hostname",
             RQ_CLIENT_ADDR, "client_addr",
             RQ_FILE, 1,
             0);

    /*
     * Examine all access-control rules.
     */
    defl_verdict = PERMIT;
    parse_table(hosts_allow_table, &request);
    defl_verdict = DENY;
    parse_table(hosts_deny_table, &request);
    return (0);
}

/* usage - explain */

static void usage()
{
    fprintf(stderr, "usage: %s [-a] [-d] [-i inet_conf] [-v]\n", myname);
    fprintf(stderr, "   -a: report rules with implicit \"ALLOW\" at end\n");
    fprintf(stderr, "   -d: use allow/deny files in current directory\n");
    fprintf(stderr, "   -i: location of inetd.conf file\n");
    fprintf(stderr, "   -v: list all rules\n");
    exit(1);
}

/* parse_table - like table_match(), but examines _all_ entries */

static void parse_table(table, request)
char   *table;
struct request_info *request;
{
    FILE   *fp;
    int     real_verdict;
    char    sv_list[BUFLEN];        /* becomes list of daemons */
    char   *cl_list;                /* becomes list of requests */
    char   *sh_cmd;                 /* becomes optional shell command */
    char    buf[BUFSIZ];
    int     verdict;
    struct tcpd_context saved_context;

    saved_context = tcpd_context;         /* stupid compilers */

    if (fp = fopen(table, "r")) {
      tcpd_context.file = table;
      tcpd_context.line = 0;
      while (xgets(sv_list, sizeof(sv_list), fp)) {
          if (sv_list[strlen(sv_list) - 1] != '\n') {
            tcpd_warn("missing newline or line too long");
            continue;
          }
          if (sv_list[0] == '#' || sv_list[strspn(sv_list, " \t\r\n")] == 0)
            continue;
          if ((cl_list = split_at(sv_list, ':')) == 0) {
            tcpd_warn("missing \":\" separator");
            continue;
          }
          sh_cmd = split_at(cl_list, ':');

          if (hosts_access_verbose)
            printf("\n>>> Rule %s line %d:\n",
                   tcpd_context.file, tcpd_context.line);

          if (hosts_access_verbose)
            print_list("daemons:  ", sv_list);
          check_daemon_list(sv_list);

          if (hosts_access_verbose)
            print_list("clients:  ", cl_list);
          check_client_list(cl_list);

#ifdef PROCESS_OPTIONS
          real_verdict = defl_verdict;
          if (sh_cmd) {
            verdict = setjmp(tcpd_buf);
            if (verdict != 0) {
                real_verdict = (verdict == AC_PERMIT);
            } else {
                dry_run = 1;
                process_options(sh_cmd, request);
                if (dry_run == 1 && real_verdict && allow_check)
                  tcpd_warn("implicit \"allow\" at end of rule");
            }
          } else if (defl_verdict && allow_check) {
            tcpd_warn("implicit \"allow\" at end of rule");
          }
          if (hosts_access_verbose)
            printf("access:   %s\n", real_verdict ? "granted" : "denied");
#else
          if (sh_cmd)
            shell_cmd(percent_x(buf, sizeof(buf), sh_cmd, request));
          if (hosts_access_verbose)
            printf("access:   %s\n", defl_verdict ? "granted" : "denied");
#endif
      }
      (void) fclose(fp);
    } else if (errno != ENOENT) {
      tcpd_warn("cannot open %s: %m", table);
    }
    tcpd_context = saved_context;
}

/* print_list - pretty-print a list */

static void print_list(title, list)
char   *title;
char   *list;
{
    char    buf[BUFLEN];
    char   *cp;
    char   *next;

    fputs(title, stdout);
    strcpy(buf, list);

    for (cp = strtok(buf, sep); cp != 0; cp = next) {
      fputs(cp, stdout);
      next = strtok((char *) 0, sep);
      if (next != 0)
          fputs(" ", stdout);
    }
    fputs("\n", stdout);
}

/* check_daemon_list - criticize daemon list */

static void check_daemon_list(list)
char   *list;
{
    char    buf[BUFLEN];
    char   *cp;
    char   *host;
    int     daemons = 0;

    strcpy(buf, list);

    for (cp = strtok(buf, sep); cp != 0; cp = strtok((char *) 0, sep)) {
      if (STR_EQ(cp, "EXCEPT")) {
          daemons = 0;
      } else {
          daemons++;
          if ((host = split_at(cp + 1, '@')) != 0 && check_host(host) > 1) {
            tcpd_warn("host %s has more than one address", host);
            tcpd_warn("(consider using an address instead)");
          }
          check_daemon(cp);
      }
    }
    if (daemons == 0)
      tcpd_warn("daemon list is empty or ends in EXCEPT");
}

/* check_client_list - criticize client list */

static void check_client_list(list)
char   *list;
{
    char    buf[BUFLEN];
    char   *cp;
    char   *host;
    int     clients = 0;

    strcpy(buf, list);

    for (cp = strtok(buf, sep); cp != 0; cp = strtok((char *) 0, sep)) {
      if (STR_EQ(cp, "EXCEPT")) {
          clients = 0;
      } else {
          clients++;
          if (host = split_at(cp + 1, '@')) {   /* user@host */
            check_user(cp);
            check_host(host);
          } else {
            check_host(cp);
          }
      }
    }
    if (clients == 0)
      tcpd_warn("client list is empty or ends in EXCEPT");
}

/* check_daemon - criticize daemon pattern */

static void check_daemon(pat)
char   *pat;
{
    if (pat[0] == '@') {
      tcpd_warn("%s: daemon name begins with \"@\"", pat);
    } else if (pat[0] == '.') {
      tcpd_warn("%s: daemon name begins with dot", pat);
    } else if (pat[strlen(pat) - 1] == '.') {
      tcpd_warn("%s: daemon name ends in dot", pat);
    } else if (STR_EQ(pat, "ALL") || STR_EQ(pat, unknown)) {
       /* void */ ;
    } else if (STR_EQ(pat, "FAIL")) {           /* obsolete */
      tcpd_warn("FAIL is no longer recognized");
      tcpd_warn("(use EXCEPT or DENY instead)");
    } else if (reserved_name(pat)) {
      tcpd_warn("%s: daemon name may be reserved word", pat);
    } else {
      switch (inet_get(pat)) {
      case WR_UNKNOWN:
          tcpd_warn("%s: no such process name in %s", pat, inetcf);
          inet_set(pat, WR_YES);          /* shut up next time */
          break;
      case WR_NOT:
          tcpd_warn("%s: service possibly not wrapped", pat);
          inet_set(pat, WR_YES);
          break;
      }
    }
}

/* check_user - criticize user pattern */

static void check_user(pat)
char   *pat;
{
    if (pat[0] == '@') {                  /* @netgroup */
      tcpd_warn("%s: user name begins with \"@\"", pat);
    } else if (pat[0] == '.') {
      tcpd_warn("%s: user name begins with dot", pat);
    } else if (pat[strlen(pat) - 1] == '.') {
      tcpd_warn("%s: user name ends in dot", pat);
    } else if (STR_EQ(pat, "ALL") || STR_EQ(pat, unknown)
             || STR_EQ(pat, "KNOWN")) {
       /* void */ ;
    } else if (STR_EQ(pat, "FAIL")) {           /* obsolete */
      tcpd_warn("FAIL is no longer recognized");
      tcpd_warn("(use EXCEPT or DENY instead)");
    } else if (reserved_name(pat)) {
      tcpd_warn("%s: user name may be reserved word", pat);
    }
}

/* check_host - criticize host pattern */

static int check_host(pat)
char   *pat;
{
    char   *mask;
    int     addr_count = 1;

    if (pat[0] == '@') {                  /* @netgroup */
#ifdef NO_NETGRENT
      /* SCO has no *netgrent() support */
#else
#ifdef NETGROUP
      char   *machinep;
      char   *userp;
      char   *domainp;

      setnetgrent(pat + 1);
      if (getnetgrent(&machinep, &userp, &domainp) == 0)
          tcpd_warn("%s: unknown or empty netgroup", pat + 1);
      endnetgrent();
#else
      tcpd_warn("netgroup support disabled");
#endif
#endif
    } else if (mask = split_at(pat, '/')) {     /* network/netmask */
      if (dot_quad_addr(pat) == INADDR_NONE
          || dot_quad_addr(mask) == INADDR_NONE)
          tcpd_warn("%s/%s: bad net/mask pattern", pat, mask);
    } else if (STR_EQ(pat, "FAIL")) {           /* obsolete */
      tcpd_warn("FAIL is no longer recognized");
      tcpd_warn("(use EXCEPT or DENY instead)");
    } else if (reserved_name(pat)) {            /* other reserved */
       /* void */ ;
    } else if (NOT_INADDR(pat)) {         /* internet name */
      if (pat[strlen(pat) - 1] == '.') {
          tcpd_warn("%s: domain or host name ends in dot", pat);
      } else if (pat[0] != '.') {
          addr_count = check_dns(pat);
      }
    } else {                              /* numeric form */
      if (STR_EQ(pat, "0.0.0.0") || STR_EQ(pat, "255.255.255.255")) {
          /* void */ ;
      } else if (pat[0] == '.') {
          tcpd_warn("%s: network number begins with dot", pat);
      } else if (pat[strlen(pat) - 1] != '.') {
          check_dns(pat);
      }
    }
    return (addr_count);
}

/* reserved_name - determine if name is reserved */

static int reserved_name(pat)
char   *pat;
{
    return (STR_EQ(pat, unknown)
          || STR_EQ(pat, "KNOWN")
          || STR_EQ(pat, paranoid)
          || STR_EQ(pat, "ALL")
          || STR_EQ(pat, "LOCAL"));
}

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