/** verify that a DS RR hashes to a key and that key signs the set */
static enum sec_status
verify_dnskeys_with_ds_rr(struct module_env* env, struct val_env* ve,
struct ub_packed_rrset_key* dnskey_rrset,
struct ub_packed_rrset_key* ds_rrset, size_t ds_idx, char** reason)
{
enum sec_status sec = sec_status_bogus;
size_t i, num, numchecked = 0, numhashok = 0;
num = rrset_get_count(dnskey_rrset);
for(i=0; i<num; i++) {
/* Skip DNSKEYs that don't match the basic criteria. */
if(ds_get_key_algo(ds_rrset, ds_idx)
!= dnskey_get_algo(dnskey_rrset, i)
|| dnskey_calc_keytag(dnskey_rrset, i)
!= ds_get_keytag(ds_rrset, ds_idx)) {
continue;
}
numchecked++;
verbose(VERB_ALGO, "attempt DS match algo %d keytag %d",
ds_get_key_algo(ds_rrset, ds_idx),
ds_get_keytag(ds_rrset, ds_idx));
/* Convert the candidate DNSKEY into a hash using the
* same DS hash algorithm. */
if(!ds_digest_match_dnskey(env, dnskey_rrset, i, ds_rrset,
ds_idx)) {
verbose(VERB_ALGO, "DS match attempt failed");
continue;
}
numhashok++;
verbose(VERB_ALGO, "DS match digest ok, trying signature");
/* Otherwise, we have a match! Make sure that the DNSKEY
* verifies *with this key* */
sec = dnskey_verify_rrset(env, ve, dnskey_rrset,
dnskey_rrset, i, reason);
if(sec == sec_status_secure) {
return sec;
}
/* If it didn't validate with the DNSKEY, try the next one! */
}
if(numchecked == 0)
algo_needs_reason(env, ds_get_key_algo(ds_rrset, ds_idx),
reason, "no keys have a DS");
else if(numhashok == 0)
*reason = "DS hash mismatches key";
else if(!*reason)
*reason = "keyset not secured by DNSKEY that matches DS";
return sec_status_bogus;
}
/** setup sig alg list from dnskey */
static void
setup_sigalg(struct ub_packed_rrset_key* dnskey, uint8_t* sigalg)
{
uint8_t a[ALGO_NEEDS_MAX];
size_t i, n = 0;
memset(a, 0, sizeof(a));
for(i=0; i<rrset_get_count(dnskey); i++) {
uint8_t algo = (uint8_t)dnskey_get_algo(dnskey, i);
if(a[algo] == 0) {
a[algo] = 1;
sigalg[n++] = algo;
}
}
sigalg[n] = 0;
}
void algo_needs_init_dnskey_add(struct algo_needs* n,
struct ub_packed_rrset_key* dnskey, uint8_t* sigalg)
{
uint8_t algo;
size_t i, total = n->num;
size_t num = rrset_get_count(dnskey);
for(i=0; i<num; i++) {
algo = (uint8_t)dnskey_get_algo(dnskey, i);
if(!dnskey_algo_id_is_supported((int)algo))
continue;
if(n->needs[algo] == 0) {
n->needs[algo] = 1;
sigalg[total] = algo;
total++;
}
}
sigalg[total] = 0;
n->num = total;
}
enum sec_status
dnskeyset_verify_rrset_sig(struct module_env* env, struct val_env* ve,
time_t now, struct ub_packed_rrset_key* rrset,
struct ub_packed_rrset_key* dnskey, size_t sig_idx,
struct rbtree_t** sortree, char** reason)
{
/* find matching keys and check them */
enum sec_status sec = sec_status_bogus;
uint16_t tag = rrset_get_sig_keytag(rrset, sig_idx);
int algo = rrset_get_sig_algo(rrset, sig_idx);
size_t i, num = rrset_get_count(dnskey);
size_t numchecked = 0;
int buf_canon = 0;
verbose(VERB_ALGO, "verify sig %d %d", (int)tag, algo);
if(!dnskey_algo_id_is_supported(algo)) {
verbose(VERB_QUERY, "verify sig: unknown algorithm");
return sec_status_insecure;
}
for(i=0; i<num; i++) {
/* see if key matches keytag and algo */
if(algo != dnskey_get_algo(dnskey, i) ||
tag != dnskey_calc_keytag(dnskey, i))
continue;
numchecked ++;
/* see if key verifies */
sec = dnskey_verify_rrset_sig(env->scratch,
env->scratch_buffer, ve, now, rrset, dnskey, i,
sig_idx, sortree, &buf_canon, reason);
if(sec == sec_status_secure)
return sec;
}
if(numchecked == 0) {
*reason = "signatures from unknown keys";
verbose(VERB_QUERY, "verify: could not find appropriate key");
return sec_status_bogus;
}
return sec_status_bogus;
}
enum sec_status
dnskey_verify_rrset(struct module_env* env, struct val_env* ve,
struct ub_packed_rrset_key* rrset, struct ub_packed_rrset_key* dnskey,
size_t dnskey_idx, char** reason)
{
enum sec_status sec;
size_t i, num, numchecked = 0;
rbtree_t* sortree = NULL;
int buf_canon = 0;
uint16_t tag = dnskey_calc_keytag(dnskey, dnskey_idx);
int algo = dnskey_get_algo(dnskey, dnskey_idx);
num = rrset_get_sigcount(rrset);
if(num == 0) {
verbose(VERB_QUERY, "rrset failed to verify due to a lack of "
"signatures");
*reason = "no signatures";
return sec_status_bogus;
}
for(i=0; i<num; i++) {
/* see if sig matches keytag and algo */
if(algo != rrset_get_sig_algo(rrset, i) ||
tag != rrset_get_sig_keytag(rrset, i))
continue;
buf_canon = 0;
sec = dnskey_verify_rrset_sig(env->scratch,
env->scratch_buffer, ve, *env->now, rrset,
dnskey, dnskey_idx, i, &sortree, &buf_canon, reason);
if(sec == sec_status_secure)
return sec;
numchecked ++;
}
verbose(VERB_ALGO, "rrset failed to verify: all signatures are bogus");
if(!numchecked) *reason = "signature missing";
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;
}
int dnskey_algo_is_supported(struct ub_packed_rrset_key* dnskey_rrset,
size_t dnskey_idx)
{
return dnskey_algo_id_is_supported(dnskey_get_algo(dnskey_rrset,
dnskey_idx));
}
enum sec_status
dnskey_verify_rrset_sig(struct regional* region, sldns_buffer* buf,
struct val_env* ve, time_t now,
struct ub_packed_rrset_key* rrset, struct ub_packed_rrset_key* dnskey,
size_t dnskey_idx, size_t sig_idx,
struct rbtree_t** sortree, int* buf_canon, char** reason)
{
enum sec_status sec;
uint8_t* sig; /* RRSIG rdata */
size_t siglen;
size_t rrnum = rrset_get_count(rrset);
uint8_t* signer; /* rrsig signer name */
size_t signer_len;
unsigned char* sigblock; /* signature rdata field */
unsigned int sigblock_len;
uint16_t ktag; /* DNSKEY key tag */
unsigned char* key; /* public key rdata field */
unsigned int keylen;
rrset_get_rdata(rrset, rrnum + sig_idx, &sig, &siglen);
/* min length of rdatalen, fixed rrsig, root signer, 1 byte sig */
if(siglen < 2+20) {
verbose(VERB_QUERY, "verify: signature too short");
*reason = "signature too short";
return sec_status_bogus;
}
if(!(dnskey_get_flags(dnskey, dnskey_idx) & DNSKEY_BIT_ZSK)) {
verbose(VERB_QUERY, "verify: dnskey without ZSK flag");
*reason = "dnskey without ZSK flag";
return sec_status_bogus;
}
if(dnskey_get_protocol(dnskey, dnskey_idx) != LDNS_DNSSEC_KEYPROTO) {
/* RFC 4034 says DNSKEY PROTOCOL MUST be 3 */
verbose(VERB_QUERY, "verify: dnskey has wrong key protocol");
*reason = "dnskey has wrong protocolnumber";
return sec_status_bogus;
}
/* verify as many fields in rrsig as possible */
signer = sig+2+18;
signer_len = dname_valid(signer, siglen-2-18);
if(!signer_len) {
verbose(VERB_QUERY, "verify: malformed signer name");
*reason = "signer name malformed";
return sec_status_bogus; /* signer name invalid */
}
if(!dname_subdomain_c(rrset->rk.dname, signer)) {
verbose(VERB_QUERY, "verify: signer name is off-tree");
*reason = "signer name off-tree";
return sec_status_bogus; /* signer name offtree */
}
sigblock = (unsigned char*)signer+signer_len;
if(siglen < 2+18+signer_len+1) {
verbose(VERB_QUERY, "verify: too short, no signature data");
*reason = "signature too short, no signature data";
return sec_status_bogus; /* sig rdf is < 1 byte */
}
sigblock_len = (unsigned int)(siglen - 2 - 18 - signer_len);
/* verify key dname == sig signer name */
if(query_dname_compare(signer, dnskey->rk.dname) != 0) {
verbose(VERB_QUERY, "verify: wrong key for rrsig");
log_nametypeclass(VERB_QUERY, "RRSIG signername is",
signer, 0, 0);
log_nametypeclass(VERB_QUERY, "the key name is",
dnskey->rk.dname, 0, 0);
*reason = "signer name mismatches key name";
return sec_status_bogus;
}
/* verify covered type */
/* memcmp works because type is in network format for rrset */
if(memcmp(sig+2, &rrset->rk.type, 2) != 0) {
verbose(VERB_QUERY, "verify: wrong type covered");
*reason = "signature covers wrong type";
return sec_status_bogus;
}
/* verify keytag and sig algo (possibly again) */
if((int)sig[2+2] != dnskey_get_algo(dnskey, dnskey_idx)) {
verbose(VERB_QUERY, "verify: wrong algorithm");
*reason = "signature has wrong algorithm";
return sec_status_bogus;
}
ktag = htons(dnskey_calc_keytag(dnskey, dnskey_idx));
if(memcmp(sig+2+16, &ktag, 2) != 0) {
verbose(VERB_QUERY, "verify: wrong keytag");
*reason = "signature has wrong keytag";
return sec_status_bogus;
}
/* verify labels is in a valid range */
if((int)sig[2+3] > dname_signame_label_count(rrset->rk.dname)) {
verbose(VERB_QUERY, "verify: labelcount out of range");
*reason = "signature labelcount out of range";
return sec_status_bogus;
}
/* original ttl, always ok */
if(!*buf_canon) {
/* create rrset canonical format in buffer, ready for
* signature */
if(!rrset_canonical(region, buf, rrset, sig+2,
18 + signer_len, sortree)) {
log_err("verify: failed due to alloc error");
return sec_status_unchecked;
}
*buf_canon = 1;
}
/* check that dnskey is available */
dnskey_get_pubkey(dnskey, dnskey_idx, &key, &keylen);
if(!key) {
verbose(VERB_QUERY, "verify: short DNSKEY RR");
return sec_status_unchecked;
}
/* verify */
sec = verify_canonrrset(buf, (int)sig[2+2],
sigblock, sigblock_len, key, keylen, reason);
if(sec == sec_status_secure) {
/* check if TTL is too high - reduce if so */
adjust_ttl(ve, now, rrset, sig+2+4, sig+2+8, sig+2+12);
/* verify inception, expiration dates
* Do this last so that if you ignore expired-sigs the
* rest is sure to be OK. */
if(!check_dates(ve, now, sig+2+8, sig+2+12, reason)) {
return sec_status_bogus;
}
}
return sec;
}
