/* $Id: acl.c,v 1.21 2005-07-12 17:39:43 rjkaes Exp $ * * This system handles Access Control for use of this daemon. A list of * domains, or IP addresses (including IP blocks) are stored in a list * which is then used to compare incoming connections. * * Copyright (C) 2000,2002 Robert James Kaes (rjkaes@users.sourceforge.net) * * 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 2, 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. */ #include "tinyproxy.h" #include "acl.h" #include "heap.h" #include "log.h" #include "network.h" #include "sock.h" #include "vector.h" /* Define how long an IPv6 address is in bytes (128 bits, 16 bytes) */ #define IPV6_LEN 16 enum acl_type { ACL_STRING, ACL_NUMERIC }; /* * Hold the information about a particular access control. We store * whether it's an ALLOW or DENY entry, and also whether it's a string * entry (like a domain name) or an IP entry. */ struct acl_s { acl_access_t access; enum acl_type type; union { char* string; struct { unsigned char octet[IPV6_LEN]; unsigned char mask[IPV6_LEN]; } ip; } address; }; /* * All the access lists are stored in a vector. */ static vector_t access_list = NULL; /* * Inserts a new access control into the list. The function will figure out * whether the location is an IP address (with optional netmask) or a * domain name. * * Returns: * -1 on failure * 0 otherwise. */ int insert_acl(char *location, acl_access_t access_type) { struct acl_s acl; int i, ret, mask; char *p, ip_dst[IPV6_LEN]; assert(location != NULL); /* * If the access list has not been set up, create it. */ if (!access_list) { access_list = vector_create(); if (!access_list) { log_message(LOG_ERR, "Unable to allocate memory for access list"); return -1; } } /* * Start populating the access control structure. */ memset(&acl, 0, sizeof(struct acl_s)); acl.access = access_type; /* * Check for a valid IP address (the simplest case) first. */ if (full_inet_pton(location, ip_dst) > 0) { acl.type = ACL_NUMERIC; memcpy(acl.address.ip.octet, ip_dst, IPV6_LEN); memset(acl.address.ip.mask, 0xff, IPV6_LEN); } else { /* * At this point we're either a hostname or an * IP address with a slash. */ p = strchr(location, '/'); if (p != NULL) { /* * We have a slash, so it's intended to be an * IP address with mask */ *p = '\0'; if (full_inet_pton(location, ip_dst) <= 0) return -1; acl.type = ACL_NUMERIC; memcpy(acl.address.ip.octet, ip_dst, IPV6_LEN); mask = strtol(p + 1, NULL, 10); for (i = 0; i != IPV6_LEN; ++i) { if (mask >= ((i + 1) * 8)) acl.address.ip.mask[i] = 0xff; else acl.address.ip.mask[i] = 0xff << (8 - (mask - i * 8)); } } else { /* In all likelihood a string */ acl.type = ACL_STRING; acl.address.string = safestrdup(location); if (!acl.address.string) return -1; } } /* * Add the entry and then clean up. */ ret = vector_append(access_list, &acl, sizeof(struct acl_s)); safefree(acl.address.string); return ret; } /* * This function is called whenever a "string" access control is found in * the ACL. From here we do both a text based string comparison, along with * a reverse name lookup comparison of the IP addresses. * * Return: 0 if host is denied * 1 if host is allowed * -1 if no tests match, so skip */ static int acl_string_processing(struct acl_s* acl, const char* ip_address, const char* string_address) { int match; struct addrinfo hints, *res, *ressave; size_t test_length, match_length; char ipbuf[512]; assert(acl && acl->type == ACL_STRING); assert(ip_address && strlen(ip_address) > 0); assert(string_address && strlen(string_address) > 0); /* * If the first character of the ACL string is a period, we need to * do a string based test only; otherwise, we can do a reverse * lookup test as well. */ if (acl->address.string[0] != '.') { memset(&hints, 0, sizeof(struct addrinfo)); hints.ai_family = AF_UNSPEC; hints.ai_socktype = SOCK_STREAM; if (getaddrinfo(acl->address.string, NULL, &hints, &res) != 0) goto STRING_TEST; ressave = res; match = FALSE; do { get_ip_string(res->ai_addr, ipbuf, sizeof(ipbuf)); if (strcmp(ip_address, ipbuf) == 0) { match = TRUE; break; } } while ((res = res->ai_next) != NULL); freeaddrinfo(ressave); if (match) { if (acl->access == ACL_DENY) return 0; else return 1; } } STRING_TEST: test_length = strlen(string_address); match_length = strlen(acl->address.string); /* * If the string length is shorter than AC string, return a -1 so * that the "driver" will skip onto the next control in the list. */ if (test_length < match_length) return -1; if (strcasecmp(string_address + (test_length - match_length), acl->address.string) == 0) { if (acl->access == ACL_DENY) return 0; else return 1; } /* Indicate that no tests succeeded, so skip to next control. */ return -1; } /* * Compare the supplied numeric IP address with the supplied ACL structure. * * Return: * 1 IP address is allowed * 0 IP address is denied * -1 neither allowed nor denied. */ static int check_numeric_acl(const struct acl_s* acl, const char* ip) { uint8_t addr[IPV6_LEN], x, y; int i; assert(acl && acl->type == ACL_NUMERIC); assert(ip && strlen(ip) > 0); if (full_inet_pton(ip, &addr) <= 0) return -1; for (i = 0; i != IPV6_LEN; ++i) { x = addr[i] & acl->address.ip.mask[i]; y = acl->address.ip.octet[i] & acl->address.ip.mask[i]; /* If x and y don't match, the IP addresses don't match */ if (x != y) return 0; } /* The addresses match, return the permission */ return (acl->access == ACL_ALLOW); } /* * Checks whether file descriptor is allowed. * * Returns: * 1 if allowed * 0 if denied */ int check_acl(int fd, const char* ip, const char* host) { struct acl_s* acl; int perm; int i; assert(fd >= 0); assert(ip != NULL); assert(host != NULL); /* * If there is no access list allow everything. */ if (!access_list) return 1; for (i = 0; i != vector_length(access_list); ++i) { acl = vector_getentry(access_list, i, NULL); switch (acl->type) { case ACL_STRING: perm = acl_string_processing(acl, ip, host); break; case ACL_NUMERIC: if (ip[0] == '\0') continue; perm = check_numeric_acl(acl, ip); break; } /* * Check the return value too see if the IP address is * allowed or denied. */ if (perm == 0) break; else if (perm == 1) return perm; } /* * Deny all connections by default. */ log_message(LOG_NOTICE, "Unauthorized connection from \"%s\" [%s].", host, ip); return 0; }