/* $NetBSD: acl.c,v 1.1.4.2 2024/02/29 11:38:37 martin Exp $ */ /* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /*! \file */ #include #include #include #include #include #include #include #include /* * Create a new ACL, including an IP table and an array with room * for 'n' ACL elements. The elements are uninitialized and the * length is 0. */ isc_result_t dns_acl_create(isc_mem_t *mctx, int n, dns_acl_t **target) { isc_result_t result; dns_acl_t *acl; /* * Work around silly limitation of isc_mem_get(). */ if (n == 0) { n = 1; } acl = isc_mem_get(mctx, sizeof(*acl)); acl->mctx = NULL; isc_mem_attach(mctx, &acl->mctx); acl->name = NULL; isc_refcount_init(&acl->refcount, 1); result = dns_iptable_create(mctx, &acl->iptable); if (result != ISC_R_SUCCESS) { isc_mem_put(mctx, acl, sizeof(*acl)); return (result); } acl->elements = NULL; acl->alloc = 0; acl->length = 0; acl->has_negatives = false; ISC_LINK_INIT(acl, nextincache); /* * Must set magic early because we use dns_acl_detach() to clean up. */ acl->magic = DNS_ACL_MAGIC; acl->elements = isc_mem_get(mctx, n * sizeof(dns_aclelement_t)); acl->alloc = n; memset(acl->elements, 0, n * sizeof(dns_aclelement_t)); *target = acl; return (ISC_R_SUCCESS); } /* * Create a new ACL and initialize it with the value "any" or "none", * depending on the value of the "neg" parameter. * "any" is a positive iptable entry with bit length 0. * "none" is the same as "!any". */ static isc_result_t dns_acl_anyornone(isc_mem_t *mctx, bool neg, dns_acl_t **target) { isc_result_t result; dns_acl_t *acl = NULL; result = dns_acl_create(mctx, 0, &acl); if (result != ISC_R_SUCCESS) { return (result); } result = dns_iptable_addprefix(acl->iptable, NULL, 0, !neg); if (result != ISC_R_SUCCESS) { dns_acl_detach(&acl); return (result); } *target = acl; return (result); } /* * Create a new ACL that matches everything. */ isc_result_t dns_acl_any(isc_mem_t *mctx, dns_acl_t **target) { return (dns_acl_anyornone(mctx, false, target)); } /* * Create a new ACL that matches nothing. */ isc_result_t dns_acl_none(isc_mem_t *mctx, dns_acl_t **target) { return (dns_acl_anyornone(mctx, true, target)); } /* * If pos is true, test whether acl is set to "{ any; }" * If pos is false, test whether acl is set to "{ none; }" */ static bool dns_acl_isanyornone(dns_acl_t *acl, bool pos) { /* Should never happen but let's be safe */ if (acl == NULL || acl->iptable == NULL || acl->iptable->radix == NULL || acl->iptable->radix->head == NULL || acl->iptable->radix->head->prefix == NULL) { return (false); } if (acl->length != 0 || dns_acl_node_count(acl) != 1) { return (false); } if (acl->iptable->radix->head->prefix->bitlen == 0 && acl->iptable->radix->head->data[0] != NULL && acl->iptable->radix->head->data[0] == acl->iptable->radix->head->data[1] && *(bool *)(acl->iptable->radix->head->data[0]) == pos) { return (true); } return (false); /* All others */ } /* * Test whether acl is set to "{ any; }" */ bool dns_acl_isany(dns_acl_t *acl) { return (dns_acl_isanyornone(acl, true)); } /* * Test whether acl is set to "{ none; }" */ bool dns_acl_isnone(dns_acl_t *acl) { return (dns_acl_isanyornone(acl, false)); } /* * Determine whether a given address or signer matches a given ACL. * For a match with a positive ACL element or iptable radix entry, * return with a positive value in match; for a match with a negated ACL * element or radix entry, return with a negative value in match. */ isc_result_t dns_acl_match(const isc_netaddr_t *reqaddr, const dns_name_t *reqsigner, const dns_acl_t *acl, const dns_aclenv_t *env, int *match, const dns_aclelement_t **matchelt) { uint16_t bitlen; isc_prefix_t pfx; isc_radix_node_t *node = NULL; const isc_netaddr_t *addr = reqaddr; isc_netaddr_t v4addr; isc_result_t result; int match_num = -1; unsigned int i; REQUIRE(reqaddr != NULL); REQUIRE(matchelt == NULL || *matchelt == NULL); if (env != NULL && env->match_mapped && addr->family == AF_INET6 && IN6_IS_ADDR_V4MAPPED(&addr->type.in6)) { isc_netaddr_fromv4mapped(&v4addr, addr); addr = &v4addr; } /* Always match with host addresses. */ bitlen = (addr->family == AF_INET6) ? 128 : 32; NETADDR_TO_PREFIX_T(addr, pfx, bitlen); /* Assume no match. */ *match = 0; /* Search radix. */ result = isc_radix_search(acl->iptable->radix, &node, &pfx); /* Found a match. */ if (result == ISC_R_SUCCESS && node != NULL) { int fam = ISC_RADIX_FAMILY(&pfx); match_num = node->node_num[fam]; if (*(bool *)node->data[fam]) { *match = match_num; } else { *match = -match_num; } } isc_refcount_destroy(&pfx.refcount); /* Now search non-radix elements for a match with a lower node_num. */ for (i = 0; i < acl->length; i++) { dns_aclelement_t *e = &acl->elements[i]; /* Already found a better match? */ if (match_num != -1 && match_num < e->node_num) { break; } if (dns_aclelement_match(reqaddr, reqsigner, e, env, matchelt)) { if (match_num == -1 || e->node_num < match_num) { if (e->negative) { *match = -e->node_num; } else { *match = e->node_num; } } break; } } return (ISC_R_SUCCESS); } /* * Merge the contents of one ACL into another. Call dns_iptable_merge() * for the IP tables, then concatenate the element arrays. * * If pos is set to false, then the nested ACL is to be negated. This * means reverse the sense of each *positive* element or IP table node, * but leave negatives alone, so as to prevent a double-negative causing * an unexpected positive match in the parent ACL. */ isc_result_t dns_acl_merge(dns_acl_t *dest, dns_acl_t *source, bool pos) { isc_result_t result; unsigned int newalloc, nelem, i; int max_node = 0, nodes; /* Resize the element array if needed. */ if (dest->length + source->length > dest->alloc) { void *newmem; newalloc = dest->alloc + source->alloc; if (newalloc < 4) { newalloc = 4; } newmem = isc_mem_get(dest->mctx, newalloc * sizeof(dns_aclelement_t)); /* Zero. */ memset(newmem, 0, newalloc * sizeof(dns_aclelement_t)); /* Copy in the original elements */ memmove(newmem, dest->elements, dest->length * sizeof(dns_aclelement_t)); /* Release the memory for the old elements array */ isc_mem_put(dest->mctx, dest->elements, dest->alloc * sizeof(dns_aclelement_t)); dest->elements = newmem; dest->alloc = newalloc; } /* * Now copy in the new elements, increasing their node_num * values so as to keep the new ACL consistent. If we're * negating, then negate positive elements, but keep negative * elements the same for security reasons. */ nelem = dest->length; dest->length += source->length; for (i = 0; i < source->length; i++) { if (source->elements[i].node_num > max_node) { max_node = source->elements[i].node_num; } /* Copy type. */ dest->elements[nelem + i].type = source->elements[i].type; /* Adjust node numbering. */ dest->elements[nelem + i].node_num = source->elements[i].node_num + dns_acl_node_count(dest); /* Duplicate nested acl. */ if (source->elements[i].type == dns_aclelementtype_nestedacl && source->elements[i].nestedacl != NULL) { dns_acl_attach(source->elements[i].nestedacl, &dest->elements[nelem + i].nestedacl); } /* Duplicate key name. */ if (source->elements[i].type == dns_aclelementtype_keyname) { dns_name_init(&dest->elements[nelem + i].keyname, NULL); dns_name_dup(&source->elements[i].keyname, dest->mctx, &dest->elements[nelem + i].keyname); } #if defined(HAVE_GEOIP2) /* Duplicate GeoIP data */ if (source->elements[i].type == dns_aclelementtype_geoip) { dest->elements[nelem + i].geoip_elem = source->elements[i].geoip_elem; } #endif /* if defined(HAVE_GEOIP2) */ /* reverse sense of positives if this is a negative acl */ if (!pos && !source->elements[i].negative) { dest->elements[nelem + i].negative = true; } else { dest->elements[nelem + i].negative = source->elements[i].negative; } } /* * Merge the iptables. Make sure the destination ACL's * node_count value is set correctly afterward. */ nodes = max_node + dns_acl_node_count(dest); result = dns_iptable_merge(dest->iptable, source->iptable, pos); if (result != ISC_R_SUCCESS) { return (result); } if (nodes > dns_acl_node_count(dest)) { dns_acl_node_count(dest) = nodes; } return (ISC_R_SUCCESS); } /* * Like dns_acl_match, but matches against the single ACL element 'e' * rather than a complete ACL, and returns true iff it matched. * * To determine whether the match was positive or negative, the * caller should examine e->negative. Since the element 'e' may be * a reference to a named ACL or a nested ACL, a matching element * returned through 'matchelt' is not necessarily 'e' itself. */ bool dns_aclelement_match(const isc_netaddr_t *reqaddr, const dns_name_t *reqsigner, const dns_aclelement_t *e, const dns_aclenv_t *env, const dns_aclelement_t **matchelt) { dns_acl_t *inner = NULL; int indirectmatch; isc_result_t result; switch (e->type) { case dns_aclelementtype_keyname: if (reqsigner != NULL && dns_name_equal(reqsigner, &e->keyname)) { if (matchelt != NULL) { *matchelt = e; } return (true); } else { return (false); } case dns_aclelementtype_nestedacl: inner = e->nestedacl; break; case dns_aclelementtype_localhost: if (env == NULL || env->localhost == NULL) { return (false); } inner = env->localhost; break; case dns_aclelementtype_localnets: if (env == NULL || env->localnets == NULL) { return (false); } inner = env->localnets; break; #if defined(HAVE_GEOIP2) case dns_aclelementtype_geoip: if (env == NULL || env->geoip == NULL) { return (false); } return (dns_geoip_match(reqaddr, env->geoip, &e->geoip_elem)); #endif /* if defined(HAVE_GEOIP2) */ default: UNREACHABLE(); } result = dns_acl_match(reqaddr, reqsigner, inner, env, &indirectmatch, matchelt); INSIST(result == ISC_R_SUCCESS); /* * Treat negative matches in indirect ACLs as "no match". * That way, a negated indirect ACL will never become a * surprise positive match through double negation. * XXXDCL this should be documented. */ if (indirectmatch > 0) { if (matchelt != NULL) { *matchelt = e; } return (true); } /* * A negative indirect match may have set *matchelt, but we don't * want it set when we return. */ if (matchelt != NULL) { *matchelt = NULL; } return (false); } void dns_acl_attach(dns_acl_t *source, dns_acl_t **target) { REQUIRE(DNS_ACL_VALID(source)); isc_refcount_increment(&source->refcount); *target = source; } static void destroy(dns_acl_t *dacl) { unsigned int i; INSIST(!ISC_LINK_LINKED(dacl, nextincache)); for (i = 0; i < dacl->length; i++) { dns_aclelement_t *de = &dacl->elements[i]; if (de->type == dns_aclelementtype_keyname) { dns_name_free(&de->keyname, dacl->mctx); } else if (de->type == dns_aclelementtype_nestedacl) { dns_acl_detach(&de->nestedacl); } } if (dacl->elements != NULL) { isc_mem_put(dacl->mctx, dacl->elements, dacl->alloc * sizeof(dns_aclelement_t)); } if (dacl->name != NULL) { isc_mem_free(dacl->mctx, dacl->name); } if (dacl->iptable != NULL) { dns_iptable_detach(&dacl->iptable); } isc_refcount_destroy(&dacl->refcount); dacl->magic = 0; isc_mem_putanddetach(&dacl->mctx, dacl, sizeof(*dacl)); } void dns_acl_detach(dns_acl_t **aclp) { REQUIRE(aclp != NULL && DNS_ACL_VALID(*aclp)); dns_acl_t *acl = *aclp; *aclp = NULL; if (isc_refcount_decrement(&acl->refcount) == 1) { destroy(acl); } } static isc_once_t insecure_prefix_once = ISC_ONCE_INIT; static isc_mutex_t insecure_prefix_lock; static bool insecure_prefix_found; static void initialize_action(void) { isc_mutex_init(&insecure_prefix_lock); } /* * Called via isc_radix_process() to find IP table nodes that are * insecure. */ static void is_insecure(isc_prefix_t *prefix, void **data) { /* * If all nonexistent or negative then this node is secure. */ if ((data[0] == NULL || !*(bool *)data[0]) && (data[1] == NULL || !*(bool *)data[1])) { return; } /* * If a loopback address found and the other family * entry doesn't exist or is negative, return. */ if (prefix->bitlen == 32 && htonl(prefix->add.sin.s_addr) == INADDR_LOOPBACK && (data[1] == NULL || !*(bool *)data[1])) { return; } if (prefix->bitlen == 128 && IN6_IS_ADDR_LOOPBACK(&prefix->add.sin6) && (data[0] == NULL || !*(bool *)data[0])) { return; } /* Non-negated, non-loopback */ insecure_prefix_found = true; /* LOCKED */ return; } /* * Return true iff the acl 'a' is considered insecure, that is, * if it contains IP addresses other than those of the local host. * This is intended for applications such as printing warning * messages for suspect ACLs; it is not intended for making access * control decisions. We make no guarantee that an ACL for which * this function returns false is safe. */ bool dns_acl_isinsecure(const dns_acl_t *a) { unsigned int i; bool insecure; RUNTIME_CHECK(isc_once_do(&insecure_prefix_once, initialize_action) == ISC_R_SUCCESS); /* * Walk radix tree to find out if there are any non-negated, * non-loopback prefixes. */ LOCK(&insecure_prefix_lock); insecure_prefix_found = false; isc_radix_process(a->iptable->radix, is_insecure); insecure = insecure_prefix_found; UNLOCK(&insecure_prefix_lock); if (insecure) { return (true); } /* Now check non-radix elements */ for (i = 0; i < a->length; i++) { dns_aclelement_t *e = &a->elements[i]; /* A negated match can never be insecure. */ if (e->negative) { continue; } switch (e->type) { case dns_aclelementtype_keyname: case dns_aclelementtype_localhost: continue; case dns_aclelementtype_nestedacl: if (dns_acl_isinsecure(e->nestedacl)) { return (true); } continue; #if defined(HAVE_GEOIP2) case dns_aclelementtype_geoip: #endif /* if defined(HAVE_GEOIP2) */ case dns_aclelementtype_localnets: return (true); default: UNREACHABLE(); } } /* No insecure elements were found. */ return (false); } /*% * Check whether an address/signer is allowed by a given acl/aclenv. */ bool dns_acl_allowed(isc_netaddr_t *addr, const dns_name_t *signer, dns_acl_t *acl, dns_aclenv_t *aclenv) { int match; isc_result_t result; if (acl == NULL) { return (true); } result = dns_acl_match(addr, signer, acl, aclenv, &match, NULL); if (result == ISC_R_SUCCESS && match > 0) { return (true); } return (false); } /* * Initialize ACL environment, setting up localhost and localnets ACLs */ isc_result_t dns_aclenv_init(isc_mem_t *mctx, dns_aclenv_t *env) { isc_result_t result; env->localhost = NULL; env->localnets = NULL; result = dns_acl_create(mctx, 0, &env->localhost); if (result != ISC_R_SUCCESS) { goto cleanup_nothing; } result = dns_acl_create(mctx, 0, &env->localnets); if (result != ISC_R_SUCCESS) { goto cleanup_localhost; } env->match_mapped = false; #if defined(HAVE_GEOIP2) env->geoip = NULL; #endif /* if defined(HAVE_GEOIP2) */ return (ISC_R_SUCCESS); cleanup_localhost: dns_acl_detach(&env->localhost); cleanup_nothing: return (result); } void dns_aclenv_copy(dns_aclenv_t *t, dns_aclenv_t *s) { dns_acl_detach(&t->localhost); dns_acl_attach(s->localhost, &t->localhost); dns_acl_detach(&t->localnets); dns_acl_attach(s->localnets, &t->localnets); t->match_mapped = s->match_mapped; #if defined(HAVE_GEOIP2) t->geoip = s->geoip; #endif /* if defined(HAVE_GEOIP2) */ } void dns_aclenv_destroy(dns_aclenv_t *env) { if (env->localhost != NULL) { dns_acl_detach(&env->localhost); } if (env->localnets != NULL) { dns_acl_detach(&env->localnets); } }