e52f740057
the acl.c code parsing a site-spec has been factored out into a new TU: hostspec. it was superior to the parsing coding in upstream.c in that it properly deals with both ipv4 and ipv6. both upstream and acl now use the new code for parsing, and upstream also for checking for a match. acl.c still uses the old matching code as it has a lot of special case code for specifications containing a hostname, and in case such a spec is encountered, tries to do reverse name lookup to see if a numeric ip matches that spec. removing that code could break existing usecases, however since that was never implemented for upstream nobody will miss it there.
298 lines
8.7 KiB
C
298 lines
8.7 KiB
C
/* tinyproxy - A fast light-weight HTTP proxy
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* Copyright (C) 2000, 2002 Robert James Kaes <rjkaes@users.sourceforge.net>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/* This system handles Access Control for use of this daemon. A list of
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* domains, or IP addresses (including IP blocks) are stored in a list
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* which is then used to compare incoming connections.
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*/
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#include "main.h"
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#include "acl.h"
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#include "heap.h"
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#include "log.h"
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#include "network.h"
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#include "sock.h"
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#include "sblist.h"
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#include "hostspec.h"
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#include <limits.h>
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/*
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* Hold the information about a particular access control. We store
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* whether it's an ALLOW or DENY entry, and also whether it's a string
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* entry (like a domain name) or an IP entry.
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*/
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struct acl_s {
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acl_access_t access;
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struct hostspec h;
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};
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/**
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* If the access list has not been set up, create it.
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*/
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static int init_access_list(acl_list_t *access_list)
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{
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if (!*access_list) {
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*access_list = sblist_new(sizeof(struct acl_s), 16);
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if (!*access_list) {
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log_message (LOG_ERR,
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"Unable to allocate memory for access list");
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return -1;
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}
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}
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return 0;
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}
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/*
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* Inserts a new access control into the list. The function will figure out
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* whether the location is an IP address (with optional netmask) or a
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* domain name.
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*
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* Returns:
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* -1 on failure
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* 0 otherwise.
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*/
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int
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insert_acl (char *location, acl_access_t access_type, acl_list_t *access_list)
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{
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struct acl_s acl;
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assert (location != NULL);
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if (init_access_list(access_list) != 0)
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return -1;
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/*
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* Start populating the access control structure.
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*/
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memset (&acl, 0, sizeof (struct acl_s));
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acl.access = access_type;
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if(hostspec_parse(location, &acl.h) || acl.h.type == HST_NONE)
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return -1;
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if(!sblist_add(*access_list, &acl)) return -1;
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return 0;
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}
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/*
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* This function is called whenever a "string" access control is found in
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* the ACL. From here we do both a text based string comparison, along with
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* a reverse name lookup comparison of the IP addresses.
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*
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* Return: 0 if host is denied
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* 1 if host is allowed
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* -1 if no tests match, so skip
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*/
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static int
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acl_string_processing (struct acl_s *acl, const char *ip_address,
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union sockaddr_union *addr, char *string_addr)
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{
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int match;
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struct addrinfo hints, *res, *ressave;
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size_t test_length, match_length;
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char ipbuf[512];
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assert (acl && acl->h.type == HST_STRING);
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assert (ip_address && strlen (ip_address) > 0);
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/*
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* If the first character of the ACL string is a period, we need to
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* do a string based test only; otherwise, we can do a reverse
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* lookup test as well.
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*/
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if (acl->h.address.string[0] != '.') {
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memset (&hints, 0, sizeof (struct addrinfo));
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hints.ai_family = AF_UNSPEC;
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hints.ai_socktype = SOCK_STREAM;
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if (getaddrinfo (acl->h.address.string, NULL, &hints, &res) != 0)
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goto STRING_TEST;
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ressave = res;
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match = FALSE;
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do {
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get_ip_string (res->ai_addr, ipbuf, sizeof (ipbuf));
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if (strcmp (ip_address, ipbuf) == 0) {
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match = TRUE;
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break;
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}
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} while ((res = res->ai_next) != NULL);
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freeaddrinfo (ressave);
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if (match) {
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if (acl->access == ACL_DENY)
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return 0;
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else
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return 1;
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}
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}
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STRING_TEST:
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if(string_addr[0] == 0) {
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/* only do costly hostname resolution when it is absolutely needed,
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and only once */
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if(getnameinfo ((void *) addr, sizeof (*addr),
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string_addr, HOSTNAME_LENGTH, NULL, 0, 0) != 0)
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return -1;
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}
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test_length = strlen (string_addr);
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match_length = strlen (acl->h.address.string);
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/*
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* If the string length is shorter than AC string, return a -1 so
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* that the "driver" will skip onto the next control in the list.
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*/
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if (test_length < match_length)
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return -1;
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if (strcasecmp
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(string_addr + (test_length - match_length),
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acl->h.address.string) == 0) {
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if (acl->access == ACL_DENY)
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return 0;
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else
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return 1;
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}
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/* Indicate that no tests succeeded, so skip to next control. */
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return -1;
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}
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/*
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* Compare the supplied numeric IP address with the supplied ACL structure.
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*
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* Return:
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* 1 IP address is allowed
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* 0 IP address is denied
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* -1 neither allowed nor denied.
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*/
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static int check_numeric_acl (const struct acl_s *acl, uint8_t addr[IPV6_LEN])
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{
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uint8_t x, y;
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int i;
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assert (acl && acl->h.type == ACL_NUMERIC);
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for (i = 0; i != IPV6_LEN; ++i) {
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x = addr[i] & acl->h.address.ip.mask[i];
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y = acl->h.address.ip.network[i];
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/* If x and y don't match, the IP addresses don't match */
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if (x != y)
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return -1;
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}
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/* The addresses match, return the permission */
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return (acl->access == ACL_ALLOW);
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}
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/*
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* Checks whether a connection is allowed.
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*
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* Returns:
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* 1 if allowed
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* 0 if denied
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*/
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int check_acl (const char *ip, union sockaddr_union *addr, acl_list_t access_list)
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{
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struct acl_s *acl;
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int perm = 0, is_numeric_addr;
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size_t i;
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char string_addr[HOSTNAME_LENGTH];
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uint8_t numeric_addr[IPV6_LEN];
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assert (ip != NULL);
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assert (addr != NULL);
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string_addr[0] = 0;
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/*
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* If there is no access list allow everything.
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*/
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if (!access_list)
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return 1;
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is_numeric_addr = (full_inet_pton (ip, &numeric_addr) > 0);
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for (i = 0; i < sblist_getsize (access_list); ++i) {
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acl = sblist_get (access_list, i);
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switch (acl->h.type) {
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case HST_STRING:
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perm = acl_string_processing (acl, ip, addr, string_addr);
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break;
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case HST_NUMERIC:
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if (ip[0] == '\0')
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continue;
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perm = is_numeric_addr
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? check_numeric_acl (acl, numeric_addr)
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: -1;
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break;
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case HST_NONE:
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perm = -1;
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break;
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}
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/*
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* Check the return value too see if the IP address is
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* allowed or denied.
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*/
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if (perm == 0)
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break;
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else if (perm == 1)
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return perm;
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}
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/*
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* Deny all connections by default.
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*/
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log_message (LOG_NOTICE, "Unauthorized connection from \"%s\".",
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ip);
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return 0;
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}
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void flush_access_list (acl_list_t access_list)
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{
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struct acl_s *acl;
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size_t i;
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if (!access_list) {
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return;
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}
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/*
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* We need to free allocated data hanging off the acl entries
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* before we can free the acl entries themselves.
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* A hierarchical memory system would be great...
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*/
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for (i = 0; i < sblist_getsize (access_list); ++i) {
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acl = sblist_get (access_list, i);
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if (acl->h.type == HST_STRING) {
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safefree (acl->h.address.string);
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}
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}
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sblist_free (access_list);
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}
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