Handle DS records for unsupported crypto algorithms correctly.

Such a DS, as long as it is validated, should allow answers
in the domain is attests to be returned as unvalidated, and not
as a validation error.

CHANGELOG

@@ -44,8 +44,13 @@ version 2.88
 	cases where is can be useful. Thanks to Dominik Derigs for
 	the patch.
 
+	Handle DS records for unsupported crypto algorithms correctly.
+	Such a DS, as long as it is validated, should allow answers
+	in the domain is attests to be returned as unvalidated, and not
+	as a validation error.
+
 	
-(version 2.87
+version 2.87
         Allow arbitrary prefix lengths in --rev-server and
 	--domain=....,local
 

src/crypto.c

@@ -309,14 +309,14 @@ static int dnsmasq_gostdsa_verify(struct blockdata *key_data, unsigned int key_l
       mpz_init(y);
     }
     
-  mpz_import(x, 32 , 1, 1, 0, 0, p);
-  mpz_import(y, 32 , 1, 1, 0, 0, p + 32);
+  mpz_import(x, 32, -1, 1, 0, 0, p);
+  mpz_import(y, 32, -1, 1, 0, 0, p + 32);
 
   if (!ecc_point_set(gost_key, x, y))
-    return 0;
+    return 0; 
   
-  mpz_import(sig_struct->r, 32, 1, 1, 0, 0, sig);
-  mpz_import(sig_struct->s, 32, 1, 1, 0, 0, sig + 32);
+  mpz_import(sig_struct->s, 32, 1, 1, 0, 0, sig);
+  mpz_import(sig_struct->r, 32, 1, 1, 0, 0, sig + 32);
   
   return nettle_gostdsa_verify(gost_key, digest_len, digest, sig_struct);
 }
@@ -390,7 +390,12 @@ static int (*verify_func(int algo))(struct blockdata *key_data, unsigned int key
       return dnsmasq_ecdsa_verify;
       
 #if MIN_VERSION(3, 1)
-    case 15: case 16:
+    case 15:
+      return dnsmasq_eddsa_verify;
+#endif
+
+#if MIN_VERSION(3, 6)
+    case 16:
       return dnsmasq_eddsa_verify;
 #endif
     }
@@ -425,7 +430,9 @@ char *ds_digest_name(int digest)
     {
     case 1: return "sha1";
     case 2: return "sha256";
-    case 3: return "gosthash94";
+#if MIN_VERSION(3, 6)
+    case 3: return "gosthash94cp";
+#endif
     case 4: return "sha384";
     default: return NULL;
     }
@@ -444,11 +451,17 @@ char *algo_digest_name(int algo)
     case 7: return "sha1";        /* RSASHA1-NSEC3-SHA1 */
     case 8: return "sha256";      /* RSA/SHA-256 */
     case 10: return "sha512";     /* RSA/SHA-512 */
-    case 12: return "gosthash94"; /* ECC-GOST */
+#if MIN_VERSION(3, 6)
+    case 12: return "gosthash94cp"; /* ECC-GOST */ 
+#endif
     case 13: return "sha256";     /* ECDSAP256SHA256 */
     case 14: return "sha384";     /* ECDSAP384SHA384 */ 	
+#if MIN_VERSION(3, 1)
     case 15: return "null_hash";  /* ED25519 */
+#  if MIN_VERSION(3, 6)
     case 16: return "null_hash";  /* ED448 */
+#  endif
+#endif
     default: return NULL;
     }
 }

src/dnssec.c

@@ -979,10 +979,13 @@ int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t plen, ch
 }
 
 /* The DNS packet is expected to contain the answer to a DS query
-   Put all DSs in the answer which are valid into the cache.
+   Put all DSs in the answer which are valid and have hash and signature algos
+   we support into the cache.
    Also handles replies which prove that there's no DS at this location, 
    either because the zone is unsigned or this isn't a zone cut. These are
    cached too.
+   If none of the DS's are for supported algos, treat the answer as if 
+   it's a proof of no DS at this location. RFC4035 para 5.2.
    return codes:
    STAT_OK          At least one valid DS found and in cache.
    STAT_BOGUS       no DS in reply or not signed, fails validation, bad packet.
@@ -993,8 +996,8 @@ int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t plen, ch
 int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname, int class)
 {
   unsigned char *p = (unsigned char *)(header+1);
-  int qtype, qclass, rc, i, neganswer, nons, neg_ttl = 0;
-  int aclass, atype, rdlen;
+  int qtype, qclass, rc, i, neganswer, nons, neg_ttl = 0, found_supported = 0;
+  int aclass, atype, rdlen, flags;
   unsigned long ttl;
   union all_addr a;
 
@@ -1065,14 +1068,22 @@ int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char
 	      algo = *p++;
 	      digest = *p++;
 	      
-	      if ((key = blockdata_alloc((char*)p, rdlen - 4)))
+	      if (!ds_digest_name(digest) || !ds_digest_name(digest))
+		{
+		  a.log.keytag = keytag;
+		  a.log.algo = algo;
+		  a.log.digest = digest;
+		  log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DS keytag %hu, algo %hu, digest %hu (not supported)", 0);
+		  neg_ttl = ttl;
+		} 
+	      else if ((key = blockdata_alloc((char*)p, rdlen - 4)))
 		{
 		  a.ds.digest = digest;
 		  a.ds.keydata = key;
 		  a.ds.algo = algo;
 		  a.ds.keytag = keytag;
 		  a.ds.keylen = rdlen - 4;
-
+		  
 		  if (!cache_insert(name, &a, class, now, ttl, F_FORWARD | F_DS | F_DNSSECOK))
 		    {
 		      blockdata_free(key);
@@ -1083,26 +1094,29 @@ int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char
 		      a.log.keytag = keytag;
 		      a.log.algo = algo;
 		      a.log.digest = digest;
-		      if (ds_digest_name(digest) && algo_digest_name(algo))
-			log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DS keytag %hu, algo %hu, digest %hu", 0);
-		      else
-			log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DS keytag %hu, algo %hu, digest %hu (not supported)", 0);
+		      log_query(F_NOEXTRA | F_KEYTAG | F_UPSTREAM, name, &a, "DS keytag %hu, algo %hu, digest %hu", 0);
+		      found_supported = 1;
 		    } 
 		}
 	      
 	      p = psave;
 	    }
+
 	  if (!ADD_RDLEN(header, p, plen, rdlen))
 	    return STAT_BOGUS; /* bad packet */
 	}
 
       cache_end_insert();
 
+      /* Fall through if no supported algo DS found. */
+      if (found_supported)
+	return STAT_OK;
     }
-  else
+  
+  flags = F_FORWARD | F_DS | F_NEG | F_DNSSECOK;
+  
+  if (neganswer)
     {
-      int flags = F_FORWARD | F_DS | F_NEG | F_DNSSECOK;
-            
       if (RCODE(header) == NXDOMAIN)
 	flags |= F_NXDOMAIN;
       
@@ -1110,17 +1124,18 @@ int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char
 	 to store presence/absence of NS. */
       if (nons)
 	flags &= ~F_DNSSECOK;
-      
-      cache_start_insert();
-	  
-      /* Use TTL from NSEC for negative cache entries */
-      if (!cache_insert(name, NULL, class, now, neg_ttl, flags))
-	return STAT_BOGUS;
-      
-      cache_end_insert();  
-      
-      log_query(F_NOEXTRA | F_UPSTREAM, name, NULL, nons ? "no DS/cut" : "no DS", 0);
     }
+  
+  cache_start_insert();
+  
+  /* Use TTL from NSEC for negative cache entries */
+  if (!cache_insert(name, NULL, class, now, neg_ttl, flags))
+    return STAT_BOGUS;
+  
+  cache_end_insert();  
+  
+  if (neganswer)
+    log_query(F_NOEXTRA | F_UPSTREAM, name, NULL, nons ? "no DS/cut" : "no DS", 0);
       
   return STAT_OK;
 }