/**
* Create a DS digest for a DNSKEY entry.
*
* @param env: module environment. Uses scratch space.
* @param dnskey_rrset: DNSKEY rrset.
* @param dnskey_idx: index of RR in rrset.
* @param ds_rrset: DS rrset
* @param ds_idx: index of RR in DS rrset.
* @param digest: digest is returned in here (must be correctly sized).
* @return false on error.
*/
static int
ds_create_dnskey_digest(struct module_env* env,
struct ub_packed_rrset_key* dnskey_rrset, size_t dnskey_idx,
struct ub_packed_rrset_key* ds_rrset, size_t ds_idx,
uint8_t* digest)
{
sldns_buffer* b = env->scratch_buffer;
uint8_t* dnskey_rdata;
size_t dnskey_len;
rrset_get_rdata(dnskey_rrset, dnskey_idx, &dnskey_rdata, &dnskey_len);
/* create digest source material in buffer
* digest = digest_algorithm( DNSKEY owner name | DNSKEY RDATA);
* DNSKEY RDATA = Flags | Protocol | Algorithm | Public Key. */
sldns_buffer_clear(b);
sldns_buffer_write(b, dnskey_rrset->rk.dname,
dnskey_rrset->rk.dname_len);
query_dname_tolower(sldns_buffer_begin(b));
sldns_buffer_write(b, dnskey_rdata+2, dnskey_len-2); /* skip rdatalen*/
sldns_buffer_flip(b);
return secalgo_ds_digest(ds_get_digest_algo(ds_rrset, ds_idx),
(unsigned char*)sldns_buffer_begin(b), sldns_buffer_limit(b),
(unsigned char*)digest);
}
int val_favorite_ds_algo(struct ub_packed_rrset_key* ds_rrset)
{
size_t i, num = rrset_get_count(ds_rrset);
int d, digest_algo = 0; /* DS digest algo 0 is not used. */
/* find favorite algo, for now, highest number supported */
for(i=0; i<num; i++) {
if(!ds_digest_algo_is_supported(ds_rrset, i) ||
!ds_key_algo_is_supported(ds_rrset, i)) {
continue;
}
d = ds_get_digest_algo(ds_rrset, i);
if(d > digest_algo)
digest_algo = d;
}
return digest_algo;
}
int ds_digest_match_dnskey(struct module_env* env,
struct ub_packed_rrset_key* dnskey_rrset, size_t dnskey_idx,
struct ub_packed_rrset_key* ds_rrset, size_t ds_idx)
{
uint8_t* ds; /* DS digest */
size_t dslen;
uint8_t* digest; /* generated digest */
size_t digestlen = ds_digest_size_algo(ds_rrset, ds_idx);
if(digestlen == 0) {
verbose(VERB_QUERY, "DS fail: not supported, or DS RR "
"format error");
return 0; /* not supported, or DS RR format error */
}
#ifndef USE_SHA1
if(fake_sha1 && ds_get_digest_algo(ds_rrset, ds_idx)==LDNS_SHA1)
return 1;
#endif
/* check digest length in DS with length from hash function */
ds_get_sigdata(ds_rrset, ds_idx, &ds, &dslen);
if(!ds || dslen != digestlen) {
verbose(VERB_QUERY, "DS fail: DS RR algo and digest do not "
"match each other");
return 0; /* DS algorithm and digest do not match */
}
digest = regional_alloc(env->scratch, digestlen);
if(!digest) {
verbose(VERB_QUERY, "DS fail: out of memory");
return 0; /* mem error */
}
if(!ds_create_dnskey_digest(env, dnskey_rrset, dnskey_idx, ds_rrset,
ds_idx, digest)) {
verbose(VERB_QUERY, "DS fail: could not calc key digest");
return 0; /* digest algo failed */
}
if(memcmp(digest, ds, dslen) != 0) {
verbose(VERB_QUERY, "DS fail: digest is different");
return 0; /* digest different */
}
return 1;
}
void algo_needs_init_ds(struct algo_needs* n, struct ub_packed_rrset_key* ds,
int fav_ds_algo, uint8_t* sigalg)
{
uint8_t algo;
size_t i, total = 0;
size_t num = rrset_get_count(ds);
memset(n->needs, 0, sizeof(uint8_t)*ALGO_NEEDS_MAX);
for(i=0; i<num; i++) {
if(ds_get_digest_algo(ds, i) != fav_ds_algo)
continue;
algo = (uint8_t)ds_get_key_algo(ds, i);
if(!dnskey_algo_id_is_supported((int)algo))
continue;
log_assert(algo != 0); /* we do not support 0 and is EOS */
if(n->needs[algo] == 0) {
n->needs[algo] = 1;
sigalg[total] = algo;
total++;
}
}
sigalg[total] = 0;
n->num = total;
}
enum sec_status
val_verify_DNSKEY_with_DS(struct module_env* env, struct val_env* ve,
struct ub_packed_rrset_key* dnskey_rrset,
struct ub_packed_rrset_key* ds_rrset, char** reason)
{
/* as long as this is false, we can consider this DS rrset to be
* equivalent to no DS rrset. */
int has_useful_ds = 0, digest_algo, alg;
struct algo_needs needs;
size_t i, num;
enum sec_status sec;
if(dnskey_rrset->rk.dname_len != ds_rrset->rk.dname_len ||
query_dname_compare(dnskey_rrset->rk.dname, ds_rrset->rk.dname)
!= 0) {
verbose(VERB_QUERY, "DNSKEY RRset did not match DS RRset "
"by name");
*reason = "DNSKEY RRset did not match DS RRset by name";
return sec_status_bogus;
}
digest_algo = val_favorite_ds_algo(ds_rrset);
algo_needs_init_ds(&needs, ds_rrset, digest_algo);
num = rrset_get_count(ds_rrset);
for(i=0; i<num; i++) {
/* Check to see if we can understand this DS.
* And check it is the strongest digest */
if(!ds_digest_algo_is_supported(ds_rrset, i) ||
!ds_key_algo_is_supported(ds_rrset, i) ||
ds_get_digest_algo(ds_rrset, i) != digest_algo) {
continue;
}
/* Once we see a single DS with a known digestID and
* algorithm, we cannot return INSECURE (with a
* "null" KeyEntry). */
has_useful_ds = true;
sec = verify_dnskeys_with_ds_rr(env, ve, dnskey_rrset,
ds_rrset, i, reason);
if(sec == sec_status_secure) {
if(algo_needs_set_secure(&needs,
(uint8_t)ds_get_key_algo(ds_rrset, i))) {
verbose(VERB_ALGO, "DS matched DNSKEY.");
return sec_status_secure;
}
} else if(sec == sec_status_bogus) {
algo_needs_set_bogus(&needs,
(uint8_t)ds_get_key_algo(ds_rrset, i));
}
}
/* None of the DS's worked out. */
/* If no DSs were understandable, then this is OK. */
if(!has_useful_ds) {
verbose(VERB_ALGO, "No usable DS records were found -- "
"treating as insecure.");
return sec_status_insecure;
}
/* If any were understandable, then it is bad. */
verbose(VERB_QUERY, "Failed to match any usable DS to a DNSKEY.");
if((alg=algo_needs_missing(&needs)) != 0) {
algo_needs_reason(env, alg, reason, "missing verification of "
"DNSKEY signature");
}
return sec_status_bogus;
}
enum sec_status
val_verify_DNSKEY_with_TA(struct module_env* env, struct val_env* ve,
struct ub_packed_rrset_key* dnskey_rrset,
struct ub_packed_rrset_key* ta_ds,
struct ub_packed_rrset_key* ta_dnskey, uint8_t* sigalg, char** reason)
{
/* as long as this is false, we can consider this anchor to be
* equivalent to no anchor. */
int has_useful_ta = 0, digest_algo = 0, alg;
struct algo_needs needs;
size_t i, num;
enum sec_status sec;
if(ta_ds && (dnskey_rrset->rk.dname_len != ta_ds->rk.dname_len ||
query_dname_compare(dnskey_rrset->rk.dname, ta_ds->rk.dname)
!= 0)) {
verbose(VERB_QUERY, "DNSKEY RRset did not match DS RRset "
"by name");
*reason = "DNSKEY RRset did not match DS RRset by name";
return sec_status_bogus;
}
if(ta_dnskey && (dnskey_rrset->rk.dname_len != ta_dnskey->rk.dname_len
|| query_dname_compare(dnskey_rrset->rk.dname, ta_dnskey->rk.dname)
!= 0)) {
verbose(VERB_QUERY, "DNSKEY RRset did not match anchor RRset "
"by name");
*reason = "DNSKEY RRset did not match anchor RRset by name";
return sec_status_bogus;
}
if(ta_ds)
digest_algo = val_favorite_ds_algo(ta_ds);
if(sigalg) {
if(ta_ds)
algo_needs_init_ds(&needs, ta_ds, digest_algo, sigalg);
else memset(&needs, 0, sizeof(needs));
if(ta_dnskey)
algo_needs_init_dnskey_add(&needs, ta_dnskey, sigalg);
}
if(ta_ds) {
num = rrset_get_count(ta_ds);
for(i=0; i<num; i++) {
/* Check to see if we can understand this DS.
* And check it is the strongest digest */
if(!ds_digest_algo_is_supported(ta_ds, i) ||
!ds_key_algo_is_supported(ta_ds, i) ||
ds_get_digest_algo(ta_ds, i) != digest_algo)
continue;
/* Once we see a single DS with a known digestID and
* algorithm, we cannot return INSECURE (with a
* "null" KeyEntry). */
has_useful_ta = 1;
sec = verify_dnskeys_with_ds_rr(env, ve, dnskey_rrset,
ta_ds, i, reason);
if(sec == sec_status_secure) {
if(!sigalg || algo_needs_set_secure(&needs,
(uint8_t)ds_get_key_algo(ta_ds, i))) {
verbose(VERB_ALGO, "DS matched DNSKEY.");
return sec_status_secure;
}
} else if(sigalg && sec == sec_status_bogus) {
algo_needs_set_bogus(&needs,
(uint8_t)ds_get_key_algo(ta_ds, i));
}
}
}
/* None of the DS's worked out: check the DNSKEYs. */
if(ta_dnskey) {
num = rrset_get_count(ta_dnskey);
for(i=0; i<num; i++) {
/* Check to see if we can understand this DNSKEY */
if(!dnskey_algo_is_supported(ta_dnskey, i))
continue;
/* we saw a useful TA */
has_useful_ta = 1;
sec = dnskey_verify_rrset(env, ve, dnskey_rrset,
ta_dnskey, i, reason);
if(sec == sec_status_secure) {
if(!sigalg || algo_needs_set_secure(&needs,
(uint8_t)dnskey_get_algo(ta_dnskey, i))) {
verbose(VERB_ALGO, "anchor matched DNSKEY.");
return sec_status_secure;
}
} else if(sigalg && sec == sec_status_bogus) {
algo_needs_set_bogus(&needs,
(uint8_t)dnskey_get_algo(ta_dnskey, i));
}
}
}
/* If no DSs were understandable, then this is OK. */
if(!has_useful_ta) {
verbose(VERB_ALGO, "No usable trust anchors were found -- "
"treating as insecure.");
return sec_status_insecure;
}
/* If any were understandable, then it is bad. */
verbose(VERB_QUERY, "Failed to match any usable anchor to a DNSKEY.");
if(sigalg && (alg=algo_needs_missing(&needs)) != 0) {
algo_needs_reason(env, alg, reason, "missing verification of "
"DNSKEY signature");
}
return sec_status_bogus;
}
/**
* Return size of DS digest according to its hash algorithm.
* @param k: DS rrset.
* @param idx: which DS.
* @return size in bytes of digest, or 0 if not supported.
*/
static size_t
ds_digest_size_algo(struct ub_packed_rrset_key* k, size_t idx)
{
return ds_digest_size_supported(ds_get_digest_algo(k, idx));
}
