File: tcpdchk.c

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 /*
  * 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>
#ifdef INET6
#include <sys/socket.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.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"

unsigned long cidr_mask_addr(char *str);

/* list of programs which are known to be linked with libwrap in debian */
static const char *const libwrap_programs[] = {
    "portmap", "mountd", "statd", "ugidd",
    "redir", "rlinetd",
    "sshd",
    "atftpd",
    "diald",
    "esound",
    "gdm", "gnome-session",
    "icecast", "icecast_admin", "icecast_client", "icecast_source",
    "mysqld",
    "ntop",
    "pptpd",
    "rquotad",
    "sendmail", "smail",
    NULL
};

 /*
  * 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.
     */
    for (c = 0; libwrap_programs[c]; c++)
	inet_set(libwrap_programs[c], WR_YES);

    /*
     * 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 \"/\"", 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 \"/\"", 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);
    }
}

#ifdef INET6
static int is_inet6_addr(pat)
    char *pat;
{
    struct addrinfo hints, *res;
    int len, ret;
    char ch;

    if (*pat != '[')
	return (0);
    len = strlen(pat);
    if ((ch = pat[len - 1]) != ']')
	return (0);
    pat[len - 1] = '\0';
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET6;
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_PASSIVE | AI_NUMERICHOST;
    if ((ret = getaddrinfo(pat + 1, NULL, &hints, &res)) == 0)
	freeaddrinfo(res);
    pat[len - 1] = ch;
    return (ret == 0);
}
#endif

/* check_host - criticize host pattern */

static int check_host(pat)
char   *pat;
{
    char    buf[BUFSIZ];
    char   *mask;
    int     addr_count = 1;
    FILE   *fp;
    struct tcpd_context saved_context;
    char   *cp;
    char   *wsp = " \t\r\n";

    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 (pat[0] == '/') {			/* /path/name */
	if ((fp = fopen(pat, "r")) != 0) {
	    saved_context = tcpd_context;
	    tcpd_context.file = pat;
	    tcpd_context.line = 0;
	    while (fgets(buf, sizeof(buf), fp)) {
		tcpd_context.line++;
		for (cp = strtok(buf, wsp); cp; cp = strtok((char *) 0, wsp))
		    check_host(cp);
	    }
	    tcpd_context = saved_context;
	    fclose(fp);
	} else if (errno != ENOENT) {
	    tcpd_warn("open %s: %m", pat);
	}
    } else if (mask = split_at(pat, '/')) {	/* network/netmask */
#ifdef INET6
	int mask_len;

	if ((dot_quad_addr(pat) == INADDR_NONE
	    || dot_quad_addr(mask) == INADDR_NONE && cidr_mask_addr(mask) == 0)
	    && (!is_inet6_addr(pat)
		|| ((mask_len = atoi(mask)) < 0 || mask_len > 128)))
#else
	if (dot_quad_addr(pat) == INADDR_NONE
	    || dot_quad_addr(mask) == INADDR_NONE && cidr_mask_addr(mask) == 0)
#endif
	    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 */ ;
#ifdef INET6
    } else if (is_inet6_addr(pat)) { /* IPv6 address */
	addr_count = 1;
#endif
    } 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"));
}