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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 07:24:22 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 07:24:22 +0000 |
commit | 45d6379135504814ab723b57f0eb8be23393a51d (patch) | |
tree | d4f2ec4acca824a8446387a758b0ce4238a4dffa /lib/dns/acl.c | |
parent | Initial commit. (diff) | |
download | bind9-upstream.tar.xz bind9-upstream.zip |
Adding upstream version 1:9.16.44.upstream/1%9.16.44upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | lib/dns/acl.c | 665 |
1 files changed, 665 insertions, 0 deletions
diff --git a/lib/dns/acl.c b/lib/dns/acl.c new file mode 100644 index 0000000..9359e53 --- /dev/null +++ b/lib/dns/acl.c @@ -0,0 +1,665 @@ +/* + * 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 <inttypes.h> +#include <stdbool.h> + +#include <isc/mem.h> +#include <isc/once.h> +#include <isc/string.h> +#include <isc/util.h> + +#include <dns/acl.h> +#include <dns/iptable.h> + +/* + * 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); + } +} |