559 lines
16 KiB
C
559 lines
16 KiB
C
/* $NetBSD: hosts_access.c,v 1.18 2006/01/08 17:20:28 jdc Exp $ */
|
|
|
|
/*
|
|
* This module implements a simple access control language that is based on
|
|
* host (or domain) names, NIS (host) netgroup names, IP addresses (or
|
|
* network numbers) and daemon process names. When a match is found the
|
|
* search is terminated, and depending on whether PROCESS_OPTIONS is defined,
|
|
* a list of options is executed or an optional shell command is executed.
|
|
*
|
|
* Host and user names are looked up on demand, provided that suitable endpoint
|
|
* information is available as sockaddr_in structures or TLI netbufs. As a
|
|
* side effect, the pattern matching process may change the contents of
|
|
* request structure fields.
|
|
*
|
|
* Diagnostics are reported through syslog(3).
|
|
*
|
|
* Compile with -DNETGROUP if your library provides support for netgroups.
|
|
*
|
|
* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
|
|
*/
|
|
|
|
#include <sys/cdefs.h>
|
|
#ifndef lint
|
|
#if 0
|
|
static char sccsid[] = "@(#) hosts_access.c 1.21 97/02/12 02:13:22";
|
|
#else
|
|
__RCSID("$NetBSD: hosts_access.c,v 1.18 2006/01/08 17:20:28 jdc Exp $");
|
|
#endif
|
|
#endif
|
|
|
|
/* System libraries. */
|
|
|
|
#include <sys/types.h>
|
|
#include <sys/param.h>
|
|
#ifdef INET6
|
|
#include <sys/socket.h>
|
|
#endif
|
|
#include <netinet/in.h>
|
|
#include <arpa/inet.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <syslog.h>
|
|
#include <ctype.h>
|
|
#include <errno.h>
|
|
#include <setjmp.h>
|
|
#include <string.h>
|
|
#include <netdb.h>
|
|
#ifdef NETGROUP
|
|
#include <netgroup.h>
|
|
#include <rpcsvc/ypclnt.h>
|
|
#endif
|
|
|
|
/* Local stuff. */
|
|
|
|
#include "tcpd.h"
|
|
|
|
/* Error handling. */
|
|
|
|
extern jmp_buf tcpd_buf;
|
|
|
|
/* Delimiters for lists of daemons or clients. */
|
|
|
|
static char sep[] = ", \t\r\n";
|
|
|
|
/* Constants to be used in assignments only, not in comparisons... */
|
|
|
|
#define YES 1
|
|
#define NO 0
|
|
|
|
/*
|
|
* These variables are globally visible so that they can be redirected in
|
|
* verification mode.
|
|
*/
|
|
|
|
char *hosts_allow_table = HOSTS_ALLOW;
|
|
char *hosts_deny_table = HOSTS_DENY;
|
|
int hosts_access_verbose = 0;
|
|
|
|
/*
|
|
* In a long-running process, we are not at liberty to just go away.
|
|
*/
|
|
|
|
int resident = (-1); /* -1, 0: unknown; +1: yes */
|
|
|
|
/* Forward declarations. */
|
|
|
|
static int table_match __P((char *, struct request_info *));
|
|
static int list_match __P((char *, struct request_info *,
|
|
int (*)(char *, struct request_info *)));
|
|
static int server_match __P((char *, struct request_info *));
|
|
static int client_match __P((char *, struct request_info *));
|
|
static int host_match __P((char *, struct host_info *));
|
|
static int rbl_match __P((char *, char *));
|
|
static int string_match __P((char *, char *));
|
|
static int masked_match __P((char *, char *, char *));
|
|
static int masked_match4 __P((char *, char *, char *));
|
|
#ifdef INET6
|
|
static int masked_match6 __P((char *, char *, char *));
|
|
#endif
|
|
|
|
/* Size of logical line buffer. */
|
|
|
|
#define BUFLEN 2048
|
|
|
|
/* hosts_access - host access control facility */
|
|
|
|
int hosts_access(request)
|
|
struct request_info *request;
|
|
{
|
|
int verdict;
|
|
|
|
/*
|
|
* If the (daemon, client) pair is matched by an entry in the file
|
|
* /etc/hosts.allow, access is granted. Otherwise, if the (daemon,
|
|
* client) pair is matched by an entry in the file /etc/hosts.deny,
|
|
* access is denied. Otherwise, access is granted. A non-existent
|
|
* access-control file is treated as an empty file.
|
|
*
|
|
* After a rule has been matched, the optional language extensions may
|
|
* decide to grant or refuse service anyway. Or, while a rule is being
|
|
* processed, a serious error is found, and it seems better to play safe
|
|
* and deny service. All this is done by jumping back into the
|
|
* hosts_access() routine, bypassing the regular return from the
|
|
* table_match() function calls below.
|
|
*/
|
|
|
|
if (resident <= 0)
|
|
resident++;
|
|
verdict = setjmp(tcpd_buf);
|
|
if (verdict != 0)
|
|
return (verdict == AC_PERMIT);
|
|
if (table_match(hosts_allow_table, request))
|
|
return (YES);
|
|
if (table_match(hosts_deny_table, request))
|
|
return (NO);
|
|
return (YES);
|
|
}
|
|
|
|
/* table_match - match table entries with (daemon, client) pair */
|
|
|
|
static int table_match(table, request)
|
|
char *table;
|
|
struct request_info *request;
|
|
{
|
|
FILE *fp;
|
|
char sv_list[BUFLEN]; /* becomes list of daemons */
|
|
char *cl_list; /* becomes list of clients */
|
|
char *sh_cmd = NULL; /* becomes optional shell command */
|
|
int match = NO;
|
|
struct tcpd_context saved_context;
|
|
|
|
saved_context = tcpd_context; /* stupid compilers */
|
|
|
|
/*
|
|
* Between the fopen() and fclose() calls, avoid jumps that may cause
|
|
* file descriptor leaks.
|
|
*/
|
|
|
|
if ((fp = fopen(table, "r")) != 0) {
|
|
tcpd_context.file = table;
|
|
tcpd_context.line = 0;
|
|
while (match == NO && xgets(sv_list, sizeof(sv_list), fp) != 0) {
|
|
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, ':');
|
|
match = list_match(sv_list, request, server_match)
|
|
&& list_match(cl_list, request, client_match);
|
|
}
|
|
(void) fclose(fp);
|
|
} else if (errno != ENOENT) {
|
|
tcpd_warn("cannot open %s: %m", table);
|
|
}
|
|
if (match) {
|
|
if (hosts_access_verbose > 1)
|
|
syslog(LOG_DEBUG, "matched: %s line %d",
|
|
tcpd_context.file, tcpd_context.line);
|
|
if (sh_cmd) {
|
|
#ifdef PROCESS_OPTIONS
|
|
process_options(sh_cmd, request);
|
|
#else
|
|
char cmd[BUFSIZ];
|
|
shell_cmd(percent_x(cmd, sizeof(cmd), sh_cmd, request));
|
|
#endif
|
|
}
|
|
}
|
|
tcpd_context = saved_context;
|
|
return (match);
|
|
}
|
|
|
|
/* list_match - match a request against a list of patterns with exceptions */
|
|
|
|
static int list_match(list, request, match_fn)
|
|
char *list;
|
|
struct request_info *request;
|
|
int (*match_fn) __P((char *, struct request_info *));
|
|
{
|
|
char *tok;
|
|
static char *last;
|
|
int l;
|
|
|
|
/*
|
|
* Process tokens one at a time. We have exhausted all possible matches
|
|
* when we reach an "EXCEPT" token or the end of the list. If we do find
|
|
* a match, look for an "EXCEPT" list and recurse to determine whether
|
|
* the match is affected by any exceptions.
|
|
*/
|
|
|
|
for (tok = strtok_r(list, sep, &last); tok != 0;
|
|
tok = strtok_r(NULL, sep, &last)) {
|
|
if (STR_EQ(tok, "EXCEPT")) /* EXCEPT: give up */
|
|
return (NO);
|
|
l = strlen(tok);
|
|
if (*tok == '[' && tok[l - 1] == ']') {
|
|
tok[l - 1] = '\0';
|
|
tok++;
|
|
}
|
|
if (match_fn(tok, request)) { /* YES: look for exceptions */
|
|
while ((tok = strtok_r(NULL, sep, &last)) && STR_NE(tok, "EXCEPT"))
|
|
/* VOID */ ;
|
|
return (tok == 0 || list_match(NULL, request, match_fn) == 0);
|
|
}
|
|
}
|
|
return (NO);
|
|
}
|
|
|
|
/* server_match - match server information */
|
|
|
|
static int server_match(tok, request)
|
|
char *tok;
|
|
struct request_info *request;
|
|
{
|
|
char *host;
|
|
|
|
if ((host = split_at(tok + 1, '@')) == 0) { /* plain daemon */
|
|
return (string_match(tok, eval_daemon(request)));
|
|
} else { /* daemon@host */
|
|
return (string_match(tok, eval_daemon(request))
|
|
&& host_match(host, request->server));
|
|
}
|
|
}
|
|
|
|
/* client_match - match client information */
|
|
|
|
static int client_match(tok, request)
|
|
char *tok;
|
|
struct request_info *request;
|
|
{
|
|
char *host;
|
|
|
|
if ((host = split_at(tok + 1, '@')) == 0) { /* plain host */
|
|
return (host_match(tok, request->client));
|
|
} else { /* user@host */
|
|
return (host_match(host, request->client)
|
|
&& string_match(tok, eval_user(request)));
|
|
}
|
|
}
|
|
|
|
/* host_match - match host name and/or address against pattern */
|
|
|
|
static int host_match(tok, host)
|
|
char *tok;
|
|
struct host_info *host;
|
|
{
|
|
char *mask;
|
|
|
|
/*
|
|
* This code looks a little hairy because we want to avoid unnecessary
|
|
* hostname lookups.
|
|
*
|
|
* The KNOWN pattern requires that both address AND name be known; some
|
|
* patterns are specific to host names or to host addresses; all other
|
|
* patterns are satisfied when either the address OR the name match.
|
|
*/
|
|
|
|
if (tok[0] == '@') { /* netgroup: look it up */
|
|
#ifdef NETGROUP
|
|
static char *mydomain = 0;
|
|
if (mydomain == 0)
|
|
yp_get_default_domain(&mydomain);
|
|
return (innetgr(tok + 1, eval_hostname(host), NULL, mydomain));
|
|
#else
|
|
tcpd_warn("netgroup support is disabled"); /* not tcpd_jump() */
|
|
return (NO);
|
|
#endif
|
|
} else if (STR_EQ(tok, "KNOWN")) { /* check address and name */
|
|
char *name = eval_hostname(host);
|
|
return (STR_NE(eval_hostaddr(host), unknown) && HOSTNAME_KNOWN(name));
|
|
} else if (STR_EQ(tok, "LOCAL")) { /* local: no dots in name */
|
|
char *name = eval_hostname(host);
|
|
return (strchr(name, '.') == 0 && HOSTNAME_KNOWN(name));
|
|
} else if (strncmp(tok, "{RBL}.", 6) == 0) { /* RBL lookup in domain */
|
|
return rbl_match(tok+6, eval_hostaddr(host));
|
|
} else if ((mask = split_at(tok, '/')) != 0) { /* net/mask */
|
|
return (masked_match(tok, mask, eval_hostaddr(host)));
|
|
} else { /* anything else */
|
|
return (string_match(tok, eval_hostaddr(host))
|
|
|| (NOT_INADDR(tok) && string_match(tok, eval_hostname(host))));
|
|
}
|
|
}
|
|
|
|
/* rbl_match() - match host by looking up in RBL domain */
|
|
|
|
static int rbl_match(rbl_domain, rbl_hostaddr)
|
|
char *rbl_domain; /* RBL domain */
|
|
char *rbl_hostaddr; /* hostaddr */
|
|
{
|
|
char *rbl_name;
|
|
unsigned long host_address;
|
|
int ret = NO;
|
|
size_t len = strlen(rbl_domain) + (4 * 4) + 2;
|
|
|
|
if (dot_quad_addr(rbl_hostaddr, &host_address) != 0) {
|
|
tcpd_warn("unable to convert %s to address", rbl_hostaddr);
|
|
return (NO);
|
|
}
|
|
host_address = ntohl(host_address);
|
|
/* construct the rbl name to look up */
|
|
if ((rbl_name = malloc(len)) == NULL) {
|
|
tcpd_jump("not enough memory to build RBL name for %s in %s", rbl_hostaddr, rbl_domain);
|
|
/* NOTREACHED */
|
|
}
|
|
snprintf(rbl_name, len, "%u.%u.%u.%u.%s",
|
|
(unsigned int) ((host_address) & 0xff),
|
|
(unsigned int) ((host_address >> 8) & 0xff),
|
|
(unsigned int) ((host_address >> 16) & 0xff),
|
|
(unsigned int) ((host_address >> 24) & 0xff),
|
|
rbl_domain);
|
|
/* look it up */
|
|
if (gethostbyname(rbl_name) != NULL) {
|
|
/* successful lookup - they're on the RBL list */
|
|
ret = YES;
|
|
}
|
|
free(rbl_name);
|
|
|
|
return ret;
|
|
}
|
|
|
|
/* string_match - match string against pattern */
|
|
|
|
static int string_match(tok, string)
|
|
char *tok;
|
|
char *string;
|
|
{
|
|
int n;
|
|
|
|
if (tok[0] == '.') { /* suffix */
|
|
n = strlen(string) - strlen(tok);
|
|
return (n > 0 && STR_EQ(tok, string + n));
|
|
} else if (STR_EQ(tok, "ALL")) { /* all: match any */
|
|
return (YES);
|
|
} else if (STR_EQ(tok, "KNOWN")) { /* not unknown */
|
|
return (STR_NE(string, unknown));
|
|
} else if (tok[(n = strlen(tok)) - 1] == '.') { /* prefix */
|
|
return (STRN_EQ(tok, string, n));
|
|
} else { /* exact match */
|
|
return (STR_EQ(tok, string));
|
|
}
|
|
}
|
|
|
|
/* masked_match - match address against netnumber/netmask */
|
|
|
|
static int masked_match(net_tok, mask_tok, string)
|
|
char *net_tok;
|
|
char *mask_tok;
|
|
char *string;
|
|
{
|
|
#ifndef INET6
|
|
return masked_match4(net_tok, mask_tok, string);
|
|
#else
|
|
/*
|
|
* masked_match4() is kept just for supporting shortened IPv4 address form.
|
|
* If we could get rid of shortened IPv4 form, we could just always use
|
|
* masked_match6().
|
|
*/
|
|
if (dot_quad_addr(net_tok, NULL) != INADDR_NONE &&
|
|
dot_quad_addr(mask_tok, NULL) != INADDR_NONE &&
|
|
dot_quad_addr(string, NULL) != INADDR_NONE) {
|
|
return masked_match4(net_tok, mask_tok, string);
|
|
} else
|
|
return masked_match6(net_tok, mask_tok, string);
|
|
#endif
|
|
}
|
|
|
|
static int masked_match4(net_tok, mask_tok, string)
|
|
char *net_tok;
|
|
char *mask_tok;
|
|
char *string;
|
|
{
|
|
unsigned long net;
|
|
unsigned long mask;
|
|
unsigned long addr;
|
|
|
|
/*
|
|
* Disallow forms other than dotted quad: the treatment that inet_addr()
|
|
* gives to forms with less than four components is inconsistent with the
|
|
* access control language. John P. Rouillard <rouilj@cs.umb.edu>.
|
|
*/
|
|
|
|
if (dot_quad_addr(string, &addr) != 0)
|
|
return (NO);
|
|
if (dot_quad_addr(net_tok, &net) != 0 ||
|
|
dot_quad_addr(mask_tok, &mask) != 0) {
|
|
tcpd_warn("bad net/mask expression: %s/%s", net_tok, mask_tok);
|
|
return (NO); /* not tcpd_jump() */
|
|
}
|
|
|
|
if ((net & ~mask) != 0)
|
|
tcpd_warn("host bits not all zero in %s/%s", net_tok, mask_tok);
|
|
|
|
return ((addr & mask) == net);
|
|
}
|
|
|
|
#ifdef INET6
|
|
static int masked_match6(net_tok, mask_tok, string)
|
|
char *net_tok;
|
|
char *mask_tok;
|
|
char *string;
|
|
{
|
|
union {
|
|
struct sockaddr sa;
|
|
struct sockaddr_in sin;
|
|
struct sockaddr_in6 sin6;
|
|
} net, mask, addr;
|
|
struct addrinfo hints, *res;
|
|
unsigned long masklen;
|
|
char *ep;
|
|
int i;
|
|
char *np, *mp, *ap;
|
|
int alen;
|
|
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = PF_UNSPEC;
|
|
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
|
|
hints.ai_flags = AI_NUMERICHOST;
|
|
if (getaddrinfo(net_tok, "0", &hints, &res) == 0) {
|
|
if (res->ai_addrlen > sizeof(net) || res->ai_next) {
|
|
freeaddrinfo(res);
|
|
return NO;
|
|
}
|
|
memcpy(&net, res->ai_addr, res->ai_addrlen);
|
|
freeaddrinfo(res);
|
|
} else
|
|
return NO;
|
|
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = net.sa.sa_family;
|
|
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
|
|
hints.ai_flags = AI_NUMERICHOST;
|
|
ep = NULL;
|
|
if (getaddrinfo(mask_tok, "0", &hints, &res) == 0) {
|
|
if (res->ai_family == AF_INET6 &&
|
|
((struct sockaddr_in6 *)res->ai_addr)->sin6_scope_id) {
|
|
freeaddrinfo(res);
|
|
return NO;
|
|
}
|
|
if (res->ai_addrlen > sizeof(mask) || res->ai_next) {
|
|
freeaddrinfo(res);
|
|
return NO;
|
|
}
|
|
memcpy(&mask, res->ai_addr, res->ai_addrlen);
|
|
freeaddrinfo(res);
|
|
} else {
|
|
ep = NULL;
|
|
masklen = strtoul(mask_tok, &ep, 10);
|
|
if (ep && !*ep) {
|
|
memset(&mask, 0, sizeof(mask));
|
|
mask.sa.sa_family = net.sa.sa_family;
|
|
mask.sa.sa_len = net.sa.sa_len;
|
|
switch (mask.sa.sa_family) {
|
|
case AF_INET:
|
|
mp = (char *)&mask.sin.sin_addr;
|
|
alen = sizeof(mask.sin.sin_addr);
|
|
break;
|
|
case AF_INET6:
|
|
mp = (char *)&mask.sin6.sin6_addr;
|
|
alen = sizeof(mask.sin6.sin6_addr);
|
|
break;
|
|
default:
|
|
return NO;
|
|
}
|
|
if (masklen / 8 > alen)
|
|
return NO;
|
|
memset(mp, 0xff, masklen / 8);
|
|
if (masklen % 8)
|
|
mp[masklen / 8] = 0xff00 >> (masklen % 8);
|
|
} else
|
|
return NO;
|
|
}
|
|
|
|
memset(&hints, 0, sizeof(hints));
|
|
hints.ai_family = PF_UNSPEC;
|
|
hints.ai_socktype = SOCK_DGRAM; /*dummy*/
|
|
hints.ai_flags = AI_NUMERICHOST;
|
|
if (getaddrinfo(string, "0", &hints, &res) == 0) {
|
|
if (res->ai_addrlen > sizeof(addr) || res->ai_next) {
|
|
freeaddrinfo(res);
|
|
return NO;
|
|
}
|
|
/* special case - IPv4 mapped address */
|
|
if (net.sa.sa_family == AF_INET && res->ai_family == AF_INET6 &&
|
|
IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)res->ai_addr)->sin6_addr)) {
|
|
memset(&addr, 0, sizeof(addr));
|
|
addr.sa.sa_family = net.sa.sa_family;
|
|
addr.sa.sa_len = net.sa.sa_len;
|
|
memcpy(&addr.sin.sin_addr,
|
|
&((struct sockaddr_in6 *)res->ai_addr)->sin6_addr.s6_addr[12],
|
|
sizeof(addr.sin.sin_addr));
|
|
} else
|
|
memcpy(&addr, res->ai_addr, res->ai_addrlen);
|
|
freeaddrinfo(res);
|
|
} else
|
|
return NO;
|
|
|
|
if (net.sa.sa_family != mask.sa.sa_family ||
|
|
net.sa.sa_family != addr.sa.sa_family) {
|
|
return NO;
|
|
}
|
|
|
|
switch (net.sa.sa_family) {
|
|
case AF_INET:
|
|
np = (char *)&net.sin.sin_addr;
|
|
mp = (char *)&mask.sin.sin_addr;
|
|
ap = (char *)&addr.sin.sin_addr;
|
|
alen = sizeof(net.sin.sin_addr);
|
|
break;
|
|
case AF_INET6:
|
|
np = (char *)&net.sin6.sin6_addr;
|
|
mp = (char *)&mask.sin6.sin6_addr;
|
|
ap = (char *)&addr.sin6.sin6_addr;
|
|
alen = sizeof(net.sin6.sin6_addr);
|
|
break;
|
|
default:
|
|
return NO;
|
|
}
|
|
|
|
for (i = 0; i < alen; i++)
|
|
if (np[i] & ~mp[i]) {
|
|
tcpd_warn("host bits not all zero in %s/%s", net_tok, mask_tok);
|
|
break;
|
|
}
|
|
|
|
for (i = 0; i < alen; i++)
|
|
ap[i] &= mp[i];
|
|
|
|
if (addr.sa.sa_family == AF_INET6 && addr.sin6.sin6_scope_id &&
|
|
addr.sin6.sin6_scope_id != net.sin6.sin6_scope_id)
|
|
return NO;
|
|
return (memcmp(ap, np, alen) == 0);
|
|
}
|
|
#endif
|