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/*
* Routines to authenticate access to a daemon (hosts allow/deny).
*
* Copyright (C) 1998 Andrew Tridgell
* Copyright (C) 2004-2014 Wayne Davison
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, visit the http://fsf.org website.
*/
#include "rsync.h"
static int allow_forward_dns;
extern const char undetermined_hostname[];
static int match_hostname(const char **host_ptr, const char *addr, const char *tok)
{
struct hostent *hp;
unsigned int i;
const char *host = *host_ptr;
if (!host || !*host)
return 0;
/* First check if the reverse-DNS-determined hostname matches. */
if (iwildmatch(tok, host))
return 1;
if (!allow_forward_dns)
return 0;
/* Fail quietly if tok is an address or wildcarded entry, not a simple hostname. */
if (!tok[strspn(tok, ".0123456789")] || tok[strcspn(tok, ":/*?[")])
return 0;
/* Now try forward-DNS on the token (config-specified hostname) and see if the IP matches. */
if (!(hp = gethostbyname(tok)))
return 0;
for (i = 0; hp->h_addr_list[i] != NULL; i++) {
if (strcmp(addr, inet_ntoa(*(struct in_addr*)(hp->h_addr_list[i]))) == 0) {
/* If reverse lookups are off, we'll use the conf-specified
* hostname in preference to UNDETERMINED. */
if (host == undetermined_hostname) {
if (!(*host_ptr = strdup(tok)))
*host_ptr = undetermined_hostname;
}
return 1;
}
}
return 0;
}
static int match_binary(const char *b1, const char *b2, const char *mask, int addrlen)
{
int i;
for (i = 0; i < addrlen; i++) {
if ((b1[i] ^ b2[i]) & mask[i])
return 0;
}
return 1;
}
static void make_mask(char *mask, int plen, int addrlen)
{
int w, b;
w = plen >> 3;
b = plen & 0x7;
if (w)
memset(mask, 0xff, w);
if (w < addrlen)
mask[w] = 0xff & (0xff<<(8-b));
if (w+1 < addrlen)
memset(mask+w+1, 0, addrlen-w-1);
return;
}
static int match_address(const char *addr, const char *tok)
{
char *p;
struct addrinfo hints, *resa, *rest;
int gai;
int ret = 0;
int addrlen = 0;
#ifdef HAVE_STRTOL
long int bits;
#else
int bits;
#endif
char mask[16];
char *a = NULL, *t = NULL;
if (!addr || !*addr)
return 0;
p = strchr(tok,'/');
if (p)
*p = '\0';
/* Fail quietly if tok is a hostname, not an address. */
if (tok[strspn(tok, ".0123456789")] && strchr(tok, ':') == NULL) {
if (p)
*p = '/';
return 0;
}
memset(&hints, 0, sizeof(hints));
hints.ai_family = PF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
#ifdef AI_NUMERICHOST
hints.ai_flags = AI_NUMERICHOST;
#endif
if (getaddrinfo(addr, NULL, &hints, &resa) != 0) {
if (p)
*p = '/';
return 0;
}
gai = getaddrinfo(tok, NULL, &hints, &rest);
if (p)
*p++ = '/';
if (gai != 0) {
rprintf(FLOG, "error matching address %s: %s\n",
tok, gai_strerror(gai));
freeaddrinfo(resa);
return 0;
}
if (rest->ai_family != resa->ai_family) {
ret = 0;
goto out;
}
switch(resa->ai_family) {
case PF_INET:
a = (char *)&((struct sockaddr_in *)resa->ai_addr)->sin_addr;
t = (char *)&((struct sockaddr_in *)rest->ai_addr)->sin_addr;
addrlen = 4;
break;
#ifdef INET6
case PF_INET6:
{
struct sockaddr_in6 *sin6a, *sin6t;
sin6a = (struct sockaddr_in6 *)resa->ai_addr;
sin6t = (struct sockaddr_in6 *)rest->ai_addr;
a = (char *)&sin6a->sin6_addr;
t = (char *)&sin6t->sin6_addr;
addrlen = 16;
#ifdef HAVE_SOCKADDR_IN6_SCOPE_ID
if (sin6t->sin6_scope_id &&
sin6a->sin6_scope_id != sin6t->sin6_scope_id) {
ret = 0;
goto out;
}
#endif
break;
}
#endif
default:
rprintf(FLOG, "unknown family %u\n", rest->ai_family);
ret = 0;
goto out;
}
bits = -1;
if (p) {
if (inet_pton(resa->ai_addr->sa_family, p, mask) <= 0) {
#ifdef HAVE_STRTOL
char *ep = NULL;
#else
unsigned char *pp;
#endif
#ifdef HAVE_STRTOL
bits = strtol(p, &ep, 10);
if (!*p || *ep) {
rprintf(FLOG, "malformed mask in %s\n", tok);
ret = 0;
goto out;
}
#else
for (pp = (unsigned char *)p; *pp; pp++) {
if (!isascii(*pp) || !isdigit(*pp)) {
rprintf(FLOG, "malformed mask in %s\n", tok);
ret = 0;
goto out;
}
}
bits = atoi(p);
#endif
if (bits == 0) {
ret = 1;
goto out;
}
if (bits < 0 || bits > (addrlen << 3)) {
rprintf(FLOG, "malformed mask in %s\n", tok);
ret = 0;
goto out;
}
}
} else {
bits = 128;
}
if (bits >= 0)
make_mask(mask, bits, addrlen);
ret = match_binary(a, t, mask, addrlen);
out:
freeaddrinfo(resa);
freeaddrinfo(rest);
return ret;
}
static int access_match(const char *list, const char *addr, const char **host_ptr)
{
char *tok;
char *list2 = strdup(list);
if (!list2)
out_of_memory("access_match");
strlower(list2);
for (tok = strtok(list2, " ,\t"); tok; tok = strtok(NULL, " ,\t")) {
if (match_hostname(host_ptr, addr, tok) || match_address(addr, tok)) {
free(list2);
return 1;
}
}
free(list2);
return 0;
}
int allow_access(const char *addr, const char **host_ptr, int i)
{
const char *allow_list = lp_hosts_allow(i);
const char *deny_list = lp_hosts_deny(i);
if (allow_list && !*allow_list)
allow_list = NULL;
if (deny_list && !*deny_list)
deny_list = NULL;
allow_forward_dns = lp_forward_lookup(i);
/* If we match an allow-list item, we always allow access. */
if (allow_list) {
if (access_match(allow_list, addr, host_ptr))
return 1;
/* For an allow-list w/o a deny-list, disallow non-matches. */
if (!deny_list)
return 0;
}
/* If we match a deny-list item (and got past any allow-list
* items), we always disallow access. */
if (deny_list && access_match(deny_list, addr, host_ptr))
return 0;
/* Allow all other access. */
return 1;
}