acl.c revision 69f3cb5abcb38f105c653c7b3df7cec33b87b292
/*
* Copyright (C) 2004-2007 Internet Systems Consortium, Inc. ("ISC")
* Copyright (C) 1999-2002 Internet Software Consortium.
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
/* $Id: acl.c,v 1.35 2007/09/19 03:03:29 marka Exp $ */
/*! \file */
#include <config.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));
if (acl == NULL)
return (ISC_R_NOMEMORY);
acl->mctx = mctx;
acl->name = NULL;
result = isc_refcount_init(&acl->refcount, 1);
if (result != ISC_R_SUCCESS) {
isc_mem_put(mctx, acl, sizeof(*acl));
return (result);
}
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;
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));
if (acl->elements == NULL) {
result = ISC_R_NOMEMORY;
goto cleanup;
}
acl->alloc = n;
memset(acl->elements, 0, n * sizeof(dns_aclelement_t));
*target = acl;
return (ISC_R_SUCCESS);
cleanup:
dns_acl_detach(&acl);
return (result);
}
/*
* 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, isc_boolean_t 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);
dns_iptable_addprefix(acl->iptable, NULL, 0, ISC_TF(!neg));
*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, ISC_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, ISC_TRUE, target));
}
/*
* If pos is ISC_TRUE, test whether acl is set to "{ any; }"
* If pos is ISC_FALSE, test whether acl is set to "{ none; }"
*/
static isc_boolean_t
dns_acl_isanyornone(dns_acl_t *acl, isc_boolean_t 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 (ISC_FALSE);
if (acl->length != 0 && acl->node_count != 1)
return (ISC_FALSE);
if (acl->iptable->radix->head->prefix->bitlen == 0 &&
*(isc_boolean_t *) (acl->iptable->radix->head->data) == pos)
return (ISC_TRUE);
return (ISC_FALSE); /* All others */
}
/*
* Test whether acl is set to "{ any; }"
*/
isc_boolean_t
dns_acl_isany(dns_acl_t *acl)
{
return (dns_acl_isanyornone(acl, ISC_TRUE));
}
/*
* Test whether acl is set to "{ none; }"
*/
isc_boolean_t
dns_acl_isnone(dns_acl_t *acl)
{
return (dns_acl_isanyornone(acl, ISC_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)
{
isc_uint16_t bitlen;
isc_prefix_t pfx;
isc_radix_node_t *node;
const isc_netaddr_t *addr;
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 == ISC_FALSE ||
reqaddr->family != AF_INET6 ||
!IN6_IS_ADDR_V4MAPPED(&reqaddr->type.in6))
addr = reqaddr;
else {
isc_netaddr_fromv4mapped(&v4addr, reqaddr);
addr = &v4addr;
}
/* Always match with host addresses. */
bitlen = reqaddr->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) {
match_num = node->node_num;
if (*(isc_boolean_t *) node->data == ISC_TRUE)
*match = match_num;
else
*match = -match_num;
}
/* 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];
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;
}
return (ISC_R_SUCCESS);
}
}
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 postive match in the parent ACL.
*/
isc_result_t
dns_acl_merge(dns_acl_t *dest, dns_acl_t *source, isc_boolean_t 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));
if (newmem == NULL)
return (ISC_R_NOMEMORY);
/* Copy in the original elements */
memcpy(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;
memcpy(&dest->elements[nelem], source->elements,
(source->length * sizeof(dns_aclelement_t)));
for (i = 0; i < source->length; i++) {
dest->elements[nelem + i].node_num =
source->elements[i].node_num + dest->node_count;
if (source->elements[i].node_num > max_node)
max_node = source->elements[i].node_num;
if (!pos && source->elements[i].negative == ISC_FALSE)
dest->elements[nelem + i].negative = ISC_TRUE;
}
/*
* Merge the iptables. Make sure the destination ACL's
* node_count value is set correctly afterward.
*/
nodes = max_node + dest->node_count;
result = dns_iptable_merge(dest->iptable, source->iptable, pos);
if (result != ISC_R_SUCCESS)
return (result);
if (nodes > dest->node_count)
dest->node_count = nodes;
return (ISC_R_SUCCESS);
}
/*
* Like dns_acl_match, but matches against the single ACL element 'e'
* rather than a complete ACL, and returns ISC_TRUE iff it matched.
*
* To determine whether the match was prositive 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.
*/
isc_boolean_t
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 (ISC_TRUE);
} else {
return (ISC_FALSE);
}
case dns_aclelementtype_nestedacl:
inner = e->nestedacl;
break;
case dns_aclelementtype_localhost:
if (env == NULL || env->localhost == NULL)
return (ISC_FALSE);
inner = env->localhost;
break;
case dns_aclelementtype_localnets:
if (env == NULL || env->localnets == NULL)
return (ISC_FALSE);
inner = env->localnets;
break;
default:
/* Should be impossible */
INSIST(0);
}
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 (ISC_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 (ISC_FALSE);
}
void
dns_acl_attach(dns_acl_t *source, dns_acl_t **target) {
REQUIRE(DNS_ACL_VALID(source));
isc_refcount_increment(&source->refcount, NULL);
*target = source;
}
static void
destroy(dns_acl_t *dacl) {
unsigned int i;
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_put(dacl->mctx, dacl, sizeof(*dacl));
}
void
dns_acl_detach(dns_acl_t **aclp) {
dns_acl_t *acl = *aclp;
unsigned int refs;
REQUIRE(DNS_ACL_VALID(acl));
isc_refcount_decrement(&acl->refcount, &refs);
if (refs == 0)
destroy(acl);
*aclp = NULL;
}
static isc_once_t insecure_prefix_once = ISC_ONCE_INIT;
static isc_mutex_t insecure_prefix_lock;
static isc_boolean_t insecure_prefix_found;
static void
initialize_action(void) {
RUNTIME_CHECK(isc_mutex_init(&insecure_prefix_lock) == ISC_R_SUCCESS);
}
/*
* Called via isc_radix_walk() to find IP table nodes that are
* insecure.
*/
static void
is_insecure(isc_prefix_t *prefix, void *data) {
isc_boolean_t secure = * (isc_boolean_t *)data;
/* Negated entries are always secure */
if (!secure) {
return;
}
/* If loopback prefix found, return */
switch (prefix->family) {
case AF_INET:
if (prefix->bitlen == 32 &&
htonl(prefix->add.sin.s_addr) == INADDR_LOOPBACK)
return;
break;
case AF_INET6:
if (prefix->bitlen == 128 &&
IN6_IS_ADDR_LOOPBACK(&prefix->add.sin6))
return;
break;
default:
break;
}
/* Non-negated, non-loopback */
insecure_prefix_found = ISC_TRUE;
return;
}
/*
* Return ISC_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 ISC_FALSE is safe.
*/
isc_boolean_t
dns_acl_isinsecure(const dns_acl_t *a) {
unsigned int i;
isc_boolean_t 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 = ISC_FALSE;
isc_radix_process(a->iptable->radix, is_insecure);
insecure = insecure_prefix_found;
UNLOCK(&insecure_prefix_lock);
if (insecure)
return(ISC_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 (ISC_TRUE);
continue;
case dns_aclelementtype_localnets:
return (ISC_TRUE);
default:
INSIST(0);
return (ISC_TRUE);
}
}
/* No insecure elements were found. */
return (ISC_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 = ISC_FALSE;
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;
}
void
dns_aclenv_destroy(dns_aclenv_t *env) {
dns_acl_detach(&env->localhost);
dns_acl_detach(&env->localnets);
}