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freebsd/contrib/ldns/dane.c
Dag-Erling Smørgrav 17d15b2511 Upgrade to latest ldns (1.6.17) and unbound (1.4.22). 
MFC after:	3 weeks
2014-05-15 03:30:03 +00:00

749 lines
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/*
* Verify or create TLS authentication with DANE (RFC6698)
*
* (c) NLnetLabs 2012
*
* See the file LICENSE for the license.
*
*/
#include <ldns/config.h>
#ifdef USE_DANE
#include <ldns/ldns.h>
#include <ldns/dane.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_NETDB_H
#include <netdb.h>
#endif
#ifdef HAVE_SSL
#include <openssl/ssl.h>
#include <openssl/err.h>
#include <openssl/x509v3.h>
#endif
ldns_status
ldns_dane_create_tlsa_owner(ldns_rdf** tlsa_owner, const ldns_rdf* name,
uint16_t port, ldns_dane_transport transport)
{
char buf[LDNS_MAX_DOMAINLEN];
size_t s;
assert(tlsa_owner != NULL);
assert(name != NULL);
assert(ldns_rdf_get_type(name) == LDNS_RDF_TYPE_DNAME);
s = (size_t)snprintf(buf, LDNS_MAX_DOMAINLEN, "X_%d", (int)port);
buf[0] = (char)(s - 1);
switch(transport) {
case LDNS_DANE_TRANSPORT_TCP:
s += snprintf(buf + s, LDNS_MAX_DOMAINLEN - s, "\004_tcp");
break;
case LDNS_DANE_TRANSPORT_UDP:
s += snprintf(buf + s, LDNS_MAX_DOMAINLEN - s, "\004_udp");
break;
case LDNS_DANE_TRANSPORT_SCTP:
s += snprintf(buf + s, LDNS_MAX_DOMAINLEN - s, "\005_sctp");
break;
default:
return LDNS_STATUS_DANE_UNKNOWN_TRANSPORT;
}
if (s + ldns_rdf_size(name) > LDNS_MAX_DOMAINLEN) {
return LDNS_STATUS_DOMAINNAME_OVERFLOW;
}
memcpy(buf + s, ldns_rdf_data(name), ldns_rdf_size(name));
*tlsa_owner = ldns_rdf_new_frm_data(LDNS_RDF_TYPE_DNAME,
s + ldns_rdf_size(name), buf);
if (*tlsa_owner == NULL) {
return LDNS_STATUS_MEM_ERR;
}
return LDNS_STATUS_OK;
}
#ifdef HAVE_SSL
ldns_status
ldns_dane_cert2rdf(ldns_rdf** rdf, X509* cert,
ldns_tlsa_selector selector,
ldns_tlsa_matching_type matching_type)
{
unsigned char* buf = NULL;
size_t len;
X509_PUBKEY* xpubkey;
EVP_PKEY* epubkey;
unsigned char* digest;
assert(rdf != NULL);
assert(cert != NULL);
switch(selector) {
case LDNS_TLSA_SELECTOR_FULL_CERTIFICATE:
len = (size_t)i2d_X509(cert, &buf);
break;
case LDNS_TLSA_SELECTOR_SUBJECTPUBLICKEYINFO:
#ifndef S_SPLINT_S
xpubkey = X509_get_X509_PUBKEY(cert);
#endif
if (! xpubkey) {
return LDNS_STATUS_SSL_ERR;
}
epubkey = X509_PUBKEY_get(xpubkey);
if (! epubkey) {
return LDNS_STATUS_SSL_ERR;
}
len = (size_t)i2d_PUBKEY(epubkey, &buf);
break;
default:
return LDNS_STATUS_DANE_UNKNOWN_SELECTOR;
}
switch(matching_type) {
case LDNS_TLSA_MATCHING_TYPE_NO_HASH_USED:
*rdf = ldns_rdf_new(LDNS_RDF_TYPE_HEX, len, buf);
return *rdf ? LDNS_STATUS_OK : LDNS_STATUS_MEM_ERR;
break;
case LDNS_TLSA_MATCHING_TYPE_SHA256:
digest = LDNS_XMALLOC(unsigned char, LDNS_SHA256_DIGEST_LENGTH);
if (digest == NULL) {
LDNS_FREE(buf);
return LDNS_STATUS_MEM_ERR;
}
(void) ldns_sha256(buf, (unsigned int)len, digest);
*rdf = ldns_rdf_new(LDNS_RDF_TYPE_HEX, LDNS_SHA256_DIGEST_LENGTH,
digest);
LDNS_FREE(buf);
return *rdf ? LDNS_STATUS_OK : LDNS_STATUS_MEM_ERR;
break;
case LDNS_TLSA_MATCHING_TYPE_SHA512:
digest = LDNS_XMALLOC(unsigned char, LDNS_SHA512_DIGEST_LENGTH);
if (digest == NULL) {
LDNS_FREE(buf);
return LDNS_STATUS_MEM_ERR;
}
(void) ldns_sha512(buf, (unsigned int)len, digest);
*rdf = ldns_rdf_new(LDNS_RDF_TYPE_HEX, LDNS_SHA512_DIGEST_LENGTH,
digest);
LDNS_FREE(buf);
return *rdf ? LDNS_STATUS_OK : LDNS_STATUS_MEM_ERR;
break;
default:
LDNS_FREE(buf);
return LDNS_STATUS_DANE_UNKNOWN_MATCHING_TYPE;
}
}
/* Ordinary PKIX validation of cert (with extra_certs to help)
* against the CA's in store
*/
static ldns_status
ldns_dane_pkix_validate(X509* cert, STACK_OF(X509)* extra_certs,
X509_STORE* store)
{
X509_STORE_CTX* vrfy_ctx;
ldns_status s;
if (! store) {
return LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
}
vrfy_ctx = X509_STORE_CTX_new();
if (! vrfy_ctx) {
return LDNS_STATUS_SSL_ERR;
} else if (X509_STORE_CTX_init(vrfy_ctx, store,
cert, extra_certs) != 1) {
s = LDNS_STATUS_SSL_ERR;
} else if (X509_verify_cert(vrfy_ctx) == 1) {
s = LDNS_STATUS_OK;
} else {
s = LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
}
X509_STORE_CTX_free(vrfy_ctx);
return s;
}
/* Orinary PKIX validation of cert (with extra_certs to help)
* against the CA's in store, but also return the validation chain.
*/
static ldns_status
ldns_dane_pkix_validate_and_get_chain(STACK_OF(X509)** chain, X509* cert,
STACK_OF(X509)* extra_certs, X509_STORE* store)
{
ldns_status s;
X509_STORE* empty_store = NULL;
X509_STORE_CTX* vrfy_ctx;
assert(chain != NULL);
if (! store) {
store = empty_store = X509_STORE_new();
}
s = LDNS_STATUS_SSL_ERR;
vrfy_ctx = X509_STORE_CTX_new();
if (! vrfy_ctx) {
goto exit_free_empty_store;
} else if (X509_STORE_CTX_init(vrfy_ctx, store,
cert, extra_certs) != 1) {
goto exit_free_vrfy_ctx;
} else if (X509_verify_cert(vrfy_ctx) == 1) {
s = LDNS_STATUS_OK;
} else {
s = LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
}
*chain = X509_STORE_CTX_get1_chain(vrfy_ctx);
if (! *chain) {
s = LDNS_STATUS_SSL_ERR;
}
exit_free_vrfy_ctx:
X509_STORE_CTX_free(vrfy_ctx);
exit_free_empty_store:
if (empty_store) {
X509_STORE_free(empty_store);
}
return s;
}
/* Return the validation chain that can be build out of cert, with extra_certs.
*/
static ldns_status
ldns_dane_pkix_get_chain(STACK_OF(X509)** chain,
X509* cert, STACK_OF(X509)* extra_certs)
{
ldns_status s;
X509_STORE* empty_store = NULL;
X509_STORE_CTX* vrfy_ctx;
assert(chain != NULL);
empty_store = X509_STORE_new();
s = LDNS_STATUS_SSL_ERR;
vrfy_ctx = X509_STORE_CTX_new();
if (! vrfy_ctx) {
goto exit_free_empty_store;
} else if (X509_STORE_CTX_init(vrfy_ctx, empty_store,
cert, extra_certs) != 1) {
goto exit_free_vrfy_ctx;
}
(void) X509_verify_cert(vrfy_ctx);
*chain = X509_STORE_CTX_get1_chain(vrfy_ctx);
if (! *chain) {
s = LDNS_STATUS_SSL_ERR;
} else {
s = LDNS_STATUS_OK;
}
exit_free_vrfy_ctx:
X509_STORE_CTX_free(vrfy_ctx);
exit_free_empty_store:
X509_STORE_free(empty_store);
return s;
}
/* Pop n+1 certs and return the last popped.
*/
static ldns_status
ldns_dane_get_nth_cert_from_validation_chain(
X509** cert, STACK_OF(X509)* chain, int n, bool ca)
{
if (n >= sk_X509_num(chain) || n < 0) {
return LDNS_STATUS_DANE_OFFSET_OUT_OF_RANGE;
}
*cert = sk_X509_pop(chain);
while (n-- > 0) {
X509_free(*cert);
*cert = sk_X509_pop(chain);
}
if (ca && ! X509_check_ca(*cert)) {
return LDNS_STATUS_DANE_NON_CA_CERTIFICATE;
}
return LDNS_STATUS_OK;
}
/* Create validation chain with cert and extra_certs and returns the last
* self-signed (if present).
*/
static ldns_status
ldns_dane_pkix_get_last_self_signed(X509** out_cert,
X509* cert, STACK_OF(X509)* extra_certs)
{
ldns_status s;
X509_STORE* empty_store = NULL;
X509_STORE_CTX* vrfy_ctx;
assert(out_cert != NULL);
empty_store = X509_STORE_new();
s = LDNS_STATUS_SSL_ERR;
vrfy_ctx = X509_STORE_CTX_new();
if (! vrfy_ctx) {
goto exit_free_empty_store;
} else if (X509_STORE_CTX_init(vrfy_ctx, empty_store,
cert, extra_certs) != 1) {
goto exit_free_vrfy_ctx;
}
(void) X509_verify_cert(vrfy_ctx);
if (vrfy_ctx->error == X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN ||
vrfy_ctx->error == X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT){
*out_cert = X509_STORE_CTX_get_current_cert( vrfy_ctx);
s = LDNS_STATUS_OK;
} else {
s = LDNS_STATUS_DANE_PKIX_NO_SELF_SIGNED_TRUST_ANCHOR;
}
exit_free_vrfy_ctx:
X509_STORE_CTX_free(vrfy_ctx);
exit_free_empty_store:
X509_STORE_free(empty_store);
return s;
}
ldns_status
ldns_dane_select_certificate(X509** selected_cert,
X509* cert, STACK_OF(X509)* extra_certs,
X509_STORE* pkix_validation_store,
ldns_tlsa_certificate_usage cert_usage, int offset)
{
ldns_status s;
STACK_OF(X509)* pkix_validation_chain = NULL;
assert(selected_cert != NULL);
assert(cert != NULL);
/* With PKIX validation explicitely turned off (pkix_validation_store
* == NULL), treat the "CA constraint" and "Service certificate
* constraint" the same as "Trust anchor assertion" and "Domain issued
* certificate" respectively.
*/
if (pkix_validation_store == NULL) {
switch (cert_usage) {
case LDNS_TLSA_USAGE_CA_CONSTRAINT:
cert_usage = LDNS_TLSA_USAGE_TRUST_ANCHOR_ASSERTION;
break;
case LDNS_TLSA_USAGE_SERVICE_CERTIFICATE_CONSTRAINT:
cert_usage = LDNS_TLSA_USAGE_DOMAIN_ISSUED_CERTIFICATE;
break;
default:
break;
}
}
/* Now what to do with each Certificate usage...
*/
switch (cert_usage) {
case LDNS_TLSA_USAGE_CA_CONSTRAINT:
s = ldns_dane_pkix_validate_and_get_chain(
&pkix_validation_chain,
cert, extra_certs,
pkix_validation_store);
if (! pkix_validation_chain) {
return s;
}
if (s == LDNS_STATUS_OK) {
if (offset == -1) {
offset = 0;
}
s = ldns_dane_get_nth_cert_from_validation_chain(
selected_cert, pkix_validation_chain,
offset, true);
}
sk_X509_pop_free(pkix_validation_chain, X509_free);
return s;
break;
case LDNS_TLSA_USAGE_SERVICE_CERTIFICATE_CONSTRAINT:
*selected_cert = cert;
return ldns_dane_pkix_validate(cert, extra_certs,
pkix_validation_store);
break;
case LDNS_TLSA_USAGE_TRUST_ANCHOR_ASSERTION:
if (offset == -1) {
s = ldns_dane_pkix_get_last_self_signed(
selected_cert, cert, extra_certs);
return s;
} else {
s = ldns_dane_pkix_get_chain(
&pkix_validation_chain,
cert, extra_certs);
if (s == LDNS_STATUS_OK) {
s =
ldns_dane_get_nth_cert_from_validation_chain(
selected_cert, pkix_validation_chain,
offset, false);
} else if (! pkix_validation_chain) {
return s;
}
sk_X509_pop_free(pkix_validation_chain, X509_free);
return s;
}
break;
case LDNS_TLSA_USAGE_DOMAIN_ISSUED_CERTIFICATE:
*selected_cert = cert;
return LDNS_STATUS_OK;
break;
default:
return LDNS_STATUS_DANE_UNKNOWN_CERTIFICATE_USAGE;
break;
}
}
ldns_status
ldns_dane_create_tlsa_rr(ldns_rr** tlsa,
ldns_tlsa_certificate_usage certificate_usage,
ldns_tlsa_selector selector,
ldns_tlsa_matching_type matching_type,
X509* cert)
{
ldns_rdf* rdf;
ldns_status s;
assert(tlsa != NULL);
assert(cert != NULL);
/* create rr */
*tlsa = ldns_rr_new_frm_type(LDNS_RR_TYPE_TLSA);
if (*tlsa == NULL) {
return LDNS_STATUS_MEM_ERR;
}
rdf = ldns_native2rdf_int8(LDNS_RDF_TYPE_INT8,
(uint8_t)certificate_usage);
if (rdf == NULL) {
goto memerror;
}
(void) ldns_rr_set_rdf(*tlsa, rdf, 0);
rdf = ldns_native2rdf_int8(LDNS_RDF_TYPE_INT8, (uint8_t)selector);
if (rdf == NULL) {
goto memerror;
}
(void) ldns_rr_set_rdf(*tlsa, rdf, 1);
rdf = ldns_native2rdf_int8(LDNS_RDF_TYPE_INT8, (uint8_t)matching_type);
if (rdf == NULL) {
goto memerror;
}
(void) ldns_rr_set_rdf(*tlsa, rdf, 2);
s = ldns_dane_cert2rdf(&rdf, cert, selector, matching_type);
if (s == LDNS_STATUS_OK) {
(void) ldns_rr_set_rdf(*tlsa, rdf, 3);
return LDNS_STATUS_OK;
}
ldns_rr_free(*tlsa);
*tlsa = NULL;
return s;
memerror:
ldns_rr_free(*tlsa);
*tlsa = NULL;
return LDNS_STATUS_MEM_ERR;
}
/* Return tlsas that actually are TLSA resource records with known values
* for the Certificate usage, Selector and Matching type rdata fields.
*/
static ldns_rr_list*
ldns_dane_filter_unusable_records(const ldns_rr_list* tlsas)
{
size_t i;
ldns_rr_list* r = ldns_rr_list_new();
ldns_rr* tlsa_rr;
if (! r) {
return NULL;
}
for (i = 0; i < ldns_rr_list_rr_count(tlsas); i++) {
tlsa_rr = ldns_rr_list_rr(tlsas, i);
if (ldns_rr_get_type(tlsa_rr) == LDNS_RR_TYPE_TLSA &&
ldns_rr_rd_count(tlsa_rr) == 4 &&
ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 0)) <= 3 &&
ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 1)) <= 1 &&
ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 2)) <= 2) {
if (! ldns_rr_list_push_rr(r, tlsa_rr)) {
ldns_rr_list_free(r);
return NULL;
}
}
}
return r;
}
/* Return whether cert/selector/matching_type matches data.
*/
static ldns_status
ldns_dane_match_cert_with_data(X509* cert, ldns_tlsa_selector selector,
ldns_tlsa_matching_type matching_type, ldns_rdf* data)
{
ldns_status s;
ldns_rdf* match_data;
s = ldns_dane_cert2rdf(&match_data, cert, selector, matching_type);
if (s == LDNS_STATUS_OK) {
if (ldns_rdf_compare(data, match_data) != 0) {
s = LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH;
}
ldns_rdf_free(match_data);
}
return s;
}
/* Return whether any certificate from the chain with selector/matching_type
* matches data.
* ca should be true if the certificate has to be a CA certificate too.
*/
static ldns_status
ldns_dane_match_any_cert_with_data(STACK_OF(X509)* chain,
ldns_tlsa_selector selector,
ldns_tlsa_matching_type matching_type,
ldns_rdf* data, bool ca)
{
ldns_status s = LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH;
size_t n, i;
X509* cert;
n = (size_t)sk_X509_num(chain);
for (i = 0; i < n; i++) {
cert = sk_X509_pop(chain);
if (! cert) {
s = LDNS_STATUS_SSL_ERR;
break;
}
s = ldns_dane_match_cert_with_data(cert,
selector, matching_type, data);
if (ca && s == LDNS_STATUS_OK && ! X509_check_ca(cert)) {
s = LDNS_STATUS_DANE_NON_CA_CERTIFICATE;
}
X509_free(cert);
if (s != LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH) {
break;
}
/* when s == LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH,
* try to match the next certificate
*/
}
return s;
}
ldns_status
ldns_dane_verify_rr(const ldns_rr* tlsa_rr,
X509* cert, STACK_OF(X509)* extra_certs,
X509_STORE* pkix_validation_store)
{
ldns_status s;
STACK_OF(X509)* pkix_validation_chain = NULL;
ldns_tlsa_certificate_usage cert_usage;
ldns_tlsa_selector selector;
ldns_tlsa_matching_type matching_type;
ldns_rdf* data;
if (! tlsa_rr) {
/* No TLSA, so regular PKIX validation
*/
return ldns_dane_pkix_validate(cert, extra_certs,
pkix_validation_store);
}
cert_usage = ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 0));
selector = ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 1));
matching_type = ldns_rdf2native_int8(ldns_rr_rdf(tlsa_rr, 2));
data = ldns_rr_rdf(tlsa_rr, 3) ;
switch (cert_usage) {
case LDNS_TLSA_USAGE_CA_CONSTRAINT:
s = ldns_dane_pkix_validate_and_get_chain(
&pkix_validation_chain,
cert, extra_certs,
pkix_validation_store);
if (! pkix_validation_chain) {
return s;
}
if (s == LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE) {
/*
* NO PKIX validation. We still try to match *any*
* certificate from the chain, so we return
* TLSA errors over PKIX errors.
*
* i.e. When the TLSA matches no certificate, we return
* TLSA_DID_NOT_MATCH and not PKIX_DID_NOT_VALIDATE
*/
s = ldns_dane_match_any_cert_with_data(
pkix_validation_chain,
selector, matching_type, data, true);
if (s == LDNS_STATUS_OK) {
/* A TLSA record did match a cert from the
* chain, thus the error is failed PKIX
* validation.
*/
s = LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE;
}
} else if (s == LDNS_STATUS_OK) {
/* PKIX validated, does the TLSA match too? */
s = ldns_dane_match_any_cert_with_data(
pkix_validation_chain,
selector, matching_type, data, true);
}
sk_X509_pop_free(pkix_validation_chain, X509_free);
return s;
break;
case LDNS_TLSA_USAGE_SERVICE_CERTIFICATE_CONSTRAINT:
s = ldns_dane_match_cert_with_data(cert,
selector, matching_type, data);
if (s == LDNS_STATUS_OK) {
return ldns_dane_pkix_validate(cert, extra_certs,
pkix_validation_store);
}
return s;
break;
case LDNS_TLSA_USAGE_TRUST_ANCHOR_ASSERTION:
s = ldns_dane_pkix_get_chain(&pkix_validation_chain,
cert, extra_certs);
if (s == LDNS_STATUS_OK) {
s = ldns_dane_match_any_cert_with_data(
pkix_validation_chain,
selector, matching_type, data, false);
} else if (! pkix_validation_chain) {
return s;
}
sk_X509_pop_free(pkix_validation_chain, X509_free);
return s;
break;
case LDNS_TLSA_USAGE_DOMAIN_ISSUED_CERTIFICATE:
return ldns_dane_match_cert_with_data(cert,
selector, matching_type, data);
break;
default:
break;
}
return LDNS_STATUS_DANE_UNKNOWN_CERTIFICATE_USAGE;
}
ldns_status
ldns_dane_verify(ldns_rr_list* tlsas,
X509* cert, STACK_OF(X509)* extra_certs,
X509_STORE* pkix_validation_store)
{
size_t i;
ldns_rr* tlsa_rr;
ldns_status s = LDNS_STATUS_OK, ps;
assert(cert != NULL);
if (tlsas && ldns_rr_list_rr_count(tlsas) > 0) {
tlsas = ldns_dane_filter_unusable_records(tlsas);
if (! tlsas) {
return LDNS_STATUS_MEM_ERR;
}
}
if (! tlsas || ldns_rr_list_rr_count(tlsas) == 0) {
/* No TLSA's, so regular PKIX validation
*/
return ldns_dane_pkix_validate(cert, extra_certs,
pkix_validation_store);
} else {
for (i = 0; i < ldns_rr_list_rr_count(tlsas); i++) {
tlsa_rr = ldns_rr_list_rr(tlsas, i);
ps = s;
s = ldns_dane_verify_rr(tlsa_rr, cert, extra_certs,
pkix_validation_store);
if (s != LDNS_STATUS_DANE_TLSA_DID_NOT_MATCH &&
s != LDNS_STATUS_DANE_PKIX_DID_NOT_VALIDATE) {
/* which would be LDNS_STATUS_OK (match)
* or some fatal error preventing use from
* trying the next TLSA record.
*/
break;
}
s = (s > ps ? s : ps); /* prefer PKIX_DID_NOT_VALIDATE
* over TLSA_DID_NOT_MATCH
*/
}
ldns_rr_list_free(tlsas);
}
return s;
}
#endif /* HAVE_SSL */
#endif /* USE_DANE */
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