Correct BNF for --trust-anchor in manpage.

0x20 encoding makes them look odd, otherwise.

CHANGELOG

@@ -82,6 +82,35 @@ version 2.91
 	to queries which arrive a dnsmasq already carrying an EDNS client
 	subnet.
 
+	Handle DS queries to auth zones. When dnsmasq is configured to
+	act as an authoritative server and has an authoritative zone
+	configured, and recieves a query for that zone _as_forwarder_
+	it answers the query directly rather than forwarding it. This
+	doesn't affect the answer, but it saves dnsmasq forwarding the
+	query to the recusor upstream, whch then bounces it back to dnsmasq
+	in auth mode. The exception should be when the query is for the root
+	of zone, for a DS RR. The answer to that has to come from the parent,
+	via the recursor, and will typically be a proof-of-nonexistence
+	since dnsmasq doesn't support signed zones. This patch suppresses
+	local answers and forces forwarding to the upstream recursor for such
+	queries. It stops breakage when a DNSSEC validating client makes
+	queries to dnsmasq acting as forwarder for a zone for which it is
+	authoritative.
+
+	Implement "DNS-0x20 encoding", for extra protection against
+	reply-spoof attacks. Since DNS queries are case-insensitive,
+	it's possible to randomly flip the case of letters in a query
+	and still get the correct answer back.
+	This adds an extra dimension for a cache-poisoning attacker
+	to guess when sending replies in-the-blind since it's expected
+	that the legitimate answer will have the same  pattern of upper
+	and lower case as the query, so any replies which don't can be
+	ignored as malicious. The amount of extra entropy clearly depends
+	on the number of a-z and A-Z characters in the query, and this
+	implementation puts a hard limit of 32 bits to make rescource
+	allocation easy. This about doubles entropy over the standard
+	random ID and random port combination. 
+
 	
 version 2.90
 	Fix reversion in --rev-server introduced in 2.88 which

Makefile

@@ -71,8 +71,8 @@ nft_cflags =    `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_NFTSET $(PKG_CONFIG
 nft_libs =      `echo $(COPTS) | $(top)/bld/pkg-wrapper HAVE_NFTSET $(PKG_CONFIG) --libs libnftables`
 version =       -DVERSION='\"`$(top)/bld/get-version $(top)`\"'
 
-sum?=$(shell $(CC) -DDNSMASQ_COMPILE_OPTS $(COPTS) -E $(top)/$(SRC)/dnsmasq.h | ( md5sum 2>/dev/null || md5 ) | cut -f 1 -d ' ')
-sum!=$(CC) -DDNSMASQ_COMPILE_OPTS $(COPTS) -E $(top)/$(SRC)/dnsmasq.h | ( md5sum 2>/dev/null || md5 ) | cut -f 1 -d ' '
+sum?=$(shell echo $(CC) -DDNSMASQ_COMPILE_FLAGS="$(CFLAGS)" -DDNSMASQ_COMPILE_OPTS $(COPTS) -E $(top)/$(SRC)/dnsmasq.h | ( md5sum 2>/dev/null || md5 ) | cut -f 1 -d ' ')
+sum!=echo $(CC) -DDNSMASQ_COMPILE_FLAGS="$(CFLAGS)" -DDNSMASQ_COMPILE_OPTS $(COPTS) -E $(top)/$(SRC)/dnsmasq.h | ( md5sum 2>/dev/null || md5 ) | cut -f 1 -d ' '
 copts_conf = .copts_$(sum)
 
 objs = cache.o rfc1035.o util.o option.o forward.o network.o \

man/dnsmasq.8

@@ -882,7 +882,7 @@ ie capable of returning DNSSEC records with data. If they are not,
 then dnsmasq will not be able to determine the trusted status of
 answers and this means that DNS service will be entirely broken.
 .TP
-.B --trust-anchor=[<class>],<domain>,<key-tag>,<algorithm>,<digest-type>,<digest>
+.B --trust-anchor=<domain>,[<class>,]<key-tag>,<algorithm>,<digest-type>,<digest>
 Provide DS records to act a trust anchors for DNSSEC
 validation. Typically these will be the DS record(s) for Key Signing
 key(s) (KSK) of the root zone,

src/auth.c

@@ -137,7 +137,7 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
       nameoffset = p - (unsigned char *)header;
 
       /* now extract name as .-concatenated string into name */
-      if (!extract_name(header, qlen, &p, name, 1, 4))
+      if (!extract_name(header, qlen, &p, name, EXTR_NAME_EXTRACT, 4))
 	return 0; /* bad packet */
  
       GETSHORT(qtype, p); 
@@ -513,7 +513,7 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
 		 nxdomain = 0;
 		 if ((crecp->flags & flag) && (local_query || filter_zone(zone, flag, &(crecp->addr))))
 		   {
-		     log_query(crecp->flags, name, &crecp->addr, record_source(crecp->uid), 0);
+		     log_query(crecp->flags & ~F_REVERSE, name, &crecp->addr, record_source(crecp->uid), 0);
 		     if (add_resource_record(header, limit, &trunc, nameoffset, &ansp, 
 					     daemon->auth_ttl, NULL, qtype, C_IN, 
 					     qtype == T_A ? "4" : "6", &crecp->addr))

src/cache.c

@@ -1852,15 +1852,31 @@ int cache_make_stat(struct txt_record *t)
 #endif
 
 /* There can be names in the cache containing control chars, don't 
-   mess up logging or open security holes. */
+   mess up logging or open security holes. Also convert to all-LC
+   so that 0x20-encoding doesn't make logs look like ransom notes
+   made out of letters cut from a newspaper.
+   Overwrites daemon->workspacename */
 static char *sanitise(char *name)
 {
-  unsigned char *r;
+  unsigned char *r = (unsigned char *)name;
+  
   if (name)
-    for (r = (unsigned char *)name; *r; r++)
-      if (!isprint((int)*r))
-	return "<name unprintable>";
-
+    {
+      char *d = name = daemon->workspacename;
+      
+      for (; *r; r++, d++)
+	if (!isprint((int)*r))
+	  return "<name unprintable>";
+	else
+	  {
+	    unsigned char c = *r;
+	    
+	    *d = (char)((c >= 'A' && c <= 'Z') ? c + 'a' - 'A' : c);
+	  }
+      
+      *d = 0;
+    }
+  
   return name;
 }
 

src/config.h

@@ -362,6 +362,11 @@ HAVE_SOCKADDR_SA_LEN
 #define HAVE_INOTIFY
 #endif
 
+/* This never compiles code, it's only used by the makefile to fingerprint builds. */
+#ifdef DNSMASQ_COMPILE_FLAGS
+static char *compile_flags = DNSMASQ_COMPILE_FLAGS;
+#endif
+
 /* Define a string indicating which options are in use.
    DNSMASQ_COMPILE_OPTS is only defined in dnsmasq.c */
 

src/dnsmasq.h

@@ -790,6 +790,7 @@ struct frec {
   int forwardall, flags;
   time_t time;
   u32 forward_timestamp;
+  unsigned int encode_bitmap;
   int forward_delay;
   struct blockdata *stash; /* saved query or saved reply, whilst we validate */
   size_t stash_len;
@@ -1386,7 +1387,7 @@ int is_rev_synth(int flag, union all_addr *addr, char *name);
 /* rfc1035.c */
 int do_doctor(struct dns_header *header, size_t qlen, char *namebuff);
 int extract_name(struct dns_header *header, size_t plen, unsigned char **pp, 
-                 char *name, int isExtract, int extrabytes);
+                 char *name, int func, unsigned int parm);
 unsigned char *skip_name(unsigned char *ansp, struct dns_header *header, size_t plen, int extrabytes);
 unsigned char *skip_questions(struct dns_header *header, size_t plen);
 unsigned char *skip_section(unsigned char *ansp, int count, struct dns_header *header, size_t plen);
@@ -1413,6 +1414,11 @@ int add_resource_record(struct dns_header *header, char *limit, int *truncp,
 			int *offset, unsigned short type, unsigned short class, char *format, ...);
 int in_arpa_name_2_addr(char *namein, union all_addr *addrp);
 int private_net(struct in_addr addr, int ban_localhost);
+/* extract_name ops */
+#define EXTR_NAME_EXTRACT   1
+#define EXTR_NAME_COMPARE   2
+#define EXTR_NAME_NOCASE    3
+#define EXTR_NAME_FLIP      4
 
 /* auth.c */
 #ifdef HAVE_AUTH

src/dnssec.c

@@ -191,7 +191,7 @@ static int get_rdata(struct dns_header *header, size_t plen, struct rdata_state
 	      /* domain-name, canonicalise */
 	      int len;
 	      
-	      if (!extract_name(header, plen, &state->ip, state->buff, 1, 0) ||
+	      if (!extract_name(header, plen, &state->ip, state->buff, EXTR_NAME_EXTRACT, 0) ||
 		  (len = to_wire(state->buff)) == 0)
 		continue;
 	      
@@ -339,7 +339,7 @@ static int explore_rrset(struct dns_header *header, size_t plen, int class, int
 
       pstart = p;
       
-      if (!(res = extract_name(header, plen, &p, name, 0, 10)))
+      if (!(res = extract_name(header, plen, &p, name, EXTR_NAME_COMPARE, 10)))
 	return 0; /* bad packet */
       
       GETSHORT(stype, p);
@@ -374,14 +374,14 @@ static int explore_rrset(struct dns_header *header, size_t plen, int class, int
 	      if (gotkey)
 		{
 		  /* If there's more than one SIG, ensure they all have same keyname */
-		  if (extract_name(header, plen, &p, keyname, 0, 0) != 1)
+		  if (extract_name(header, plen, &p, keyname, EXTR_NAME_COMPARE, 0) != 1)
 		    return 0;
 		}
 	      else
 		{
 		  gotkey = 1;
 		  
-		  if (!extract_name(header, plen, &p, keyname, 1, 0))
+		  if (!extract_name(header, plen, &p, keyname, EXTR_NAME_EXTRACT, 0))
 		    return 0;
 		  
 		  /* RFC 4035 5.3.1 says that the Signer's Name field MUST equal
@@ -503,7 +503,7 @@ static int validate_rrset(time_t now, struct dns_header *header, size_t plen, in
       GETLONG(sig_inception, p);
       GETSHORT(key_tag, p);
       
-      if (!extract_name(header, plen, &p, keyname, 1, 0))
+      if (!extract_name(header, plen, &p, keyname, EXTR_NAME_EXTRACT, 0))
 	return STAT_BOGUS;
 
       if (!time_check)
@@ -568,7 +568,7 @@ static int validate_rrset(time_t now, struct dns_header *header, size_t plen, in
 	  
 	  p = rrset[i];
 	  
-	  if (!extract_name(header, plen, &p, name, 1, 10)) 
+	  if (!extract_name(header, plen, &p, name, EXTR_NAME_EXTRACT, 10)) 
 	    return STAT_BOGUS;
 
 	  name_start = name;
@@ -661,7 +661,7 @@ static int validate_rrset(time_t now, struct dns_header *header, size_t plen, in
       
       /* namebuff used for workspace above, restore to leave unchanged on exit */
       p = (unsigned char*)(rrset[0]);
-      if (!extract_name(header, plen, &p, name, 1, 0))
+      if (!extract_name(header, plen, &p, name, EXTR_NAME_EXTRACT, 0))
 	return STAT_BOGUS;
 
       if (key)
@@ -727,7 +727,7 @@ int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t plen, ch
   static unsigned char **cached_digest;
   static size_t cached_digest_size = 0;
 
-  if (ntohs(header->qdcount) != 1 || RCODE(header) != NOERROR || !extract_name(header, plen, &p, name, 1, 4))
+  if (ntohs(header->qdcount) != 1 || RCODE(header) != NOERROR || !extract_name(header, plen, &p, name, EXTR_NAME_EXTRACT, 4))
     return STAT_BOGUS | DNSSEC_FAIL_NOKEY;
 
   GETSHORT(qtype, p);
@@ -752,7 +752,7 @@ int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t plen, ch
   for (j = ntohs(header->ancount); j != 0; j--) 
     {
       /* Ensure we have type, class  TTL and length */
-      if (!(rc = extract_name(header, plen, &p, name, 0, 10)))
+      if (!(rc = extract_name(header, plen, &p, name, EXTR_NAME_COMPARE, 10)))
 	return STAT_BOGUS; /* bad packet */
   
       GETSHORT(qtype, p); 
@@ -904,7 +904,7 @@ int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t plen, ch
 	      for (j = ntohs(header->ancount); j != 0; j--) 
 		{
 		  /* Ensure we have type, class  TTL and length */
-		  if (!(rc = extract_name(header, plen, &p, name, 0, 10)))
+		  if (!(rc = extract_name(header, plen, &p, name, EXTR_NAME_COMPARE, 10)))
 		    return STAT_BOGUS; /* bad packet */
 		  
 		  GETSHORT(qtype, p); 
@@ -1024,7 +1024,7 @@ int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char
 	}
       
       p = (unsigned char *)(header+1);
-      if (!extract_name(header, plen, &p, name, 1, 4))
+      if (!extract_name(header, plen, &p, name, EXTR_NAME_EXTRACT, 4))
 	return STAT_BOGUS;
 
       p += 4; /* qtype, qclass */
@@ -1050,7 +1050,7 @@ int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char
 	{
 	  unsigned char *psave;
 
-	  if (!(rc = extract_name(header, plen, &p, name, 0, 10)))
+	  if (!(rc = extract_name(header, plen, &p, name, EXTR_NAME_COMPARE, 10)))
 	    return STAT_BOGUS; /* bad packet */
 	  
 	  GETSHORT(atype, p);
@@ -1231,12 +1231,12 @@ static int prove_non_existence_nsec(struct dns_header *header, size_t plen, unsi
       int sig_labels, name_labels;
 
       p = nsecs[i];
-      if (!extract_name(header, plen, &p, workspace1, 1, 10))
+      if (!extract_name(header, plen, &p, workspace1, EXTR_NAME_EXTRACT, 10))
 	return DNSSEC_FAIL_BADPACKET;
       p += 8; /* class, type, TTL */
       GETSHORT(rdlen, p);
       psave = p;
-      if (!extract_name(header, plen, &p, workspace2, 1, 0))
+      if (!extract_name(header, plen, &p, workspace2, EXTR_NAME_EXTRACT, 0))
 	return DNSSEC_FAIL_BADPACKET;
 
       /* If NSEC comes from wildcard expansion, use original wildcard
@@ -1400,7 +1400,7 @@ static int check_nsec3_coverage(struct dns_header *header, size_t plen, int dige
   for (i = 0; i < nsec_count; i++)
     if ((p = nsecs[i]))
       {
-       	if (!extract_name(header, plen, &p, workspace1, 1, 10) ||
+       	if (!extract_name(header, plen, &p, workspace1, EXTR_NAME_EXTRACT, 10) ||
 	    !(base32_len = base32_decode(workspace1, (unsigned char *)workspace2)))
 	  return 0;
 	
@@ -1609,7 +1609,7 @@ static int prove_non_existence_nsec3(struct dns_header *header, size_t plen, uns
       for (i = 0; i < nsec_count; i++)
 	if ((p = nsecs[i]))
 	  {
-	    if (!extract_name(header, plen, &p, workspace1, 1, 0))
+	    if (!extract_name(header, plen, &p, workspace1, EXTR_NAME_EXTRACT, 0))
 	      return DNSSEC_FAIL_BADPACKET;
 
 	    if (!(base32_len = base32_decode(workspace1, (unsigned char *)workspace2)))
@@ -1684,7 +1684,7 @@ static int prove_non_existence(struct dns_header *header, size_t plen, char *key
     {
       unsigned char *pstart = p;
       
-      if (!extract_name(header, plen, &p, daemon->workspacename, 1, 10))
+      if (!extract_name(header, plen, &p, daemon->workspacename, EXTR_NAME_EXTRACT, 10))
 	return DNSSEC_FAIL_BADPACKET;
 	  
       GETSHORT(type, p); 
@@ -1735,7 +1735,7 @@ static int prove_non_existence(struct dns_header *header, size_t plen, char *key
 		{
 		  unsigned char *psav;
 
-		  if (!(res = extract_name(header, plen, &p1, daemon->workspacename, 0, 10)))
+		  if (!(res = extract_name(header, plen, &p1, daemon->workspacename, EXTR_NAME_COMPARE, 10)))
 		    return DNSSEC_FAIL_BADPACKET;
 		  
 		   GETSHORT(type1, p1); 
@@ -1965,7 +1965,7 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
   targets[0] = p1;
   targetidx = 1;
    
-  if (!extract_name(header, plen, &p1, name, 1, 4))
+  if (!extract_name(header, plen, &p1, name, EXTR_NAME_EXTRACT, 4))
     return STAT_BOGUS;
   
   GETSHORT(qtype, p1);
@@ -2003,7 +2003,7 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
       if (i != 0 && !ADD_RDLEN(header, p1, plen, rdlen1))
 	return STAT_BOGUS;
       
-      if (!extract_name(header, plen, &p1, name, 1, 10))
+      if (!extract_name(header, plen, &p1, name, EXTR_NAME_EXTRACT, 10))
 	return STAT_BOGUS; /* bad packet */
       
       GETSHORT(type1, p1);
@@ -2018,7 +2018,7 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
       /* Check if we've done this RRset already */
       for (p2 = ans_start, j = 0; j < i; j++)
 	{
-	  if (!(rc = extract_name(header, plen, &p2, name, 0, 10)))
+	  if (!(rc = extract_name(header, plen, &p2, name, EXTR_NAME_COMPARE, 10)))
 	    return STAT_BOGUS; /* bad packet */
 	  
 	  GETSHORT(type2, p2);
@@ -2115,7 +2115,7 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
 		    if ((p2 = targets[j]))
 		      {
 			int rc1;
-			if (!(rc1 = extract_name(header, plen, &p2, name, 0, 10)))
+			if (!(rc1 = extract_name(header, plen, &p2, name, EXTR_NAME_COMPARE, 10)))
 			  return STAT_BOGUS; /* bad packet */
 			
 			if (class1 == qclass && rc1 == 1 && (type1 == T_CNAME || type1 == qtype || qtype == T_ANY ))
@@ -2149,7 +2149,7 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
 	if (neganswer)
 	  *neganswer = 1;
 	
-	if (!extract_name(header, plen, &p2, name, 1, 10))
+	if (!extract_name(header, plen, &p2, name, EXTR_NAME_EXTRACT, 10))
 	  return STAT_BOGUS; /* bad packet */
 	
 	/* NXDOMAIN or NODATA reply, unanswered question is (name, qclass, qtype) */

src/forward.c

@@ -264,6 +264,8 @@ static void forward_query(int udpfd, union mysockaddr *udpaddr,
   /* new query */
   if (!forward)
     {
+      unsigned char *p;
+
       if (OPCODE(header) != QUERY)
 	{
 	  flags = F_RCODE;
@@ -323,7 +325,12 @@ static void forward_query(int udpfd, union mysockaddr *udpaddr,
       forward->frec_src.orig_id = ntohs(header->id);
       forward->new_id = get_id();
       header->id = ntohs(forward->new_id);
-            
+      
+      forward->encode_bitmap = rand32();
+      p = (unsigned char *)(header+1);
+      if (!extract_name(header, plen, &p, NULL, EXTR_NAME_FLIP, forward->encode_bitmap))
+	goto reply;
+      
       /* Keep copy of query for retries and move to TCP */
       if (!(forward->stash = blockdata_alloc((char *)header, plen)))
 	{
@@ -822,10 +829,6 @@ static void dnssec_validate(struct frec *forward, struct dns_header *header,
 
   daemon->log_display_id = forward->frec_src.log_id;
     
-  /* We've had a reply already, which we're validating. Ignore this duplicate */
-  if (forward->blocking_query || (forward->flags & FREC_GONE_TO_TCP))
-    return;
-
   /* Find the original query that started it all.... */
   for (orig = forward; orig->dependent; orig = orig->dependent);
   
@@ -972,7 +975,8 @@ static void dnssec_validate(struct frec *forward, struct dns_header *header,
 		  new->flags &= ~(FREC_DNSKEY_QUERY | FREC_DS_QUERY);
 		  new->flags |= flags;
 		  new->forwardall = 0;
-		  
+		  new->encode_bitmap = 0;
+
 		  forward->next_dependent = NULL;
 		  new->dependent = forward; /* to find query awaiting new one. */
 		  
@@ -1089,7 +1093,7 @@ void reply_query(int fd, time_t now)
     return;
 
   p = (unsigned char *)(header+1);
-  if (!extract_name(header, n, &p, daemon->namebuff, 1, 4))
+  if (!extract_name(header, n, &p, daemon->namebuff, EXTR_NAME_EXTRACT, 4))
     return; /* bad packet */
   GETSHORT(rrtype, p); 
   GETSHORT(class, p);
@@ -1152,18 +1156,20 @@ void reply_query(int fd, time_t now)
   if (daemon->ignore_addr && RCODE(header) == NOERROR &&
       check_for_ignored_address(header, n))
     return;
-  
-  if ((RCODE(header) == REFUSED || RCODE(header) == SERVFAIL) && forward->forwardall == 0)
-    /* for broken servers, attempt to send to another one. */
-    {
+
 #ifdef HAVE_DNSSEC
       /* The query MAY have got a good answer, and be awaiting
 	 the results of further queries, in which case
-	 The Stash contains something else and we don't need to retry anyway. */
+	 the stash contains something else and we don't need to retry anyway.
+	 We may also have already got a truncated reply, and be in the process
+	 of doing the query by TCP so can ignore further, probably truncated, UDP answers. */
       if (forward->blocking_query || (forward->flags & FREC_GONE_TO_TCP))
 	return;
 #endif
       
+  if ((RCODE(header) == REFUSED || RCODE(header) == SERVFAIL) && forward->forwardall == 0)
+    /* for broken servers, attempt to send to another one. */
+    {
       /* Get the saved query back. */
       blockdata_retrieve(forward->stash, forward->stash_len, (void *)header);
       
@@ -1197,7 +1203,11 @@ void reply_query(int fd, time_t now)
   /* denominator controls how many queries we average over. */
   server->query_latency = server->mma_latency/128;
   
-  
+  /* Flip the bits back in the query name. */
+  p = (unsigned char *)(header+1);
+  if (!extract_name(header, n, &p, NULL, EXTR_NAME_FLIP, forward->encode_bitmap))
+    return;
+      
 #ifdef HAVE_DNSSEC
   if (option_bool(OPT_DNSSEC_VALID))
     {
@@ -1693,15 +1703,27 @@ void receive_query(struct listener *listen, time_t now)
 			   &source_addr, auth_dns ? "auth" : "query", type);
       
 #ifdef HAVE_AUTH
-      /* find queries for zones we're authoritative for, and answer them directly */
+      /* Find queries for zones we're authoritative for, and answer them directly.
+	 The exception to this is DS queries for the zone route. They
+	 have to come from the parent zone. Since dnsmasq's auth server
+	 can't do DNSSEC, the zone will be unsigned, and anything using
+	 dnsmasq as a forwarder and doing validation will be expecting to
+	 see the proof of non-existence from the parent. */
       if (!auth_dns && !option_bool(OPT_LOCALISE))
 	for (zone = daemon->auth_zones; zone; zone = zone->next)
-	  if (in_zone(zone, daemon->namebuff, NULL))
-	    {
-	      auth_dns = 1;
-	      local_auth = 1;
-	      break;
-	    }
+	  {
+	    char *cut;
+	    
+	    if (in_zone(zone, daemon->namebuff, &cut))
+	      {
+		if (type != T_DS || cut)
+		  {
+		    auth_dns = 1;
+		    local_auth = 1;
+		  }
+		break;
+	      }
+	  }
 #endif
       
 #ifdef HAVE_LOOP
@@ -1885,7 +1907,7 @@ static ssize_t tcp_talk(int first, int last, int start, unsigned char *packet,
 
   /* Save the query to make sure we get the answer we expect. */
   p = (unsigned char *)(header+1);
-  if (!extract_name(header, qsize, &p, daemon->namebuff, 1, 4))
+  if (!extract_name(header, qsize, &p, daemon->namebuff, EXTR_NAME_EXTRACT, 4))
     return 0;
   GETSHORT(type, p); 
   GETSHORT(class, p);
@@ -1989,12 +2011,12 @@ static ssize_t tcp_talk(int first, int last, int start, unsigned char *packet,
 	    continue;
 	}
 
-      /* If the question section of the reply doesn't match the crc we sent, then
+      /* If the question section of the reply doesn't match the question we sent, then
 	 someone might be attempting to insert bogus values into the cache by 
-	 sending replies containing questions and bogus answers. 
+	 sending replies containing questions and bogus answers.
 	 Try another server, or give up */
       p = (unsigned char *)(header+1);
-      if (extract_name(header, rsize, &p, daemon->namebuff, 0, 4) != 1)
+      if (extract_name(header, rsize, &p, daemon->namebuff, EXTR_NAME_NOCASE, 4) != 1)
 	continue;
       GETSHORT(rtype, p); 
       GETSHORT(rclass, p);
@@ -2327,15 +2349,27 @@ unsigned char *tcp_request(int confd, time_t now,
 				   &peer_addr, auth_dns ? "auth" : "query", qtype);
 	      
 #ifdef HAVE_AUTH
-	      /* find queries for zones we're authoritative for, and answer them directly */
+	      /* Find queries for zones we're authoritative for, and answer them directly.
+		 The exception to this is DS queries for the zone route. They
+		 have to come from the parent zone. Since dnsmasq's auth server
+		 can't do DNSSEC, the zone will be unsigned, and anything using
+		 dnsmasq as a forwarder and doing validation will be expecting to
+		 see the proof of non-existence from the parent. */
 	      if (!auth_dns && !option_bool(OPT_LOCALISE))
 		for (zone = daemon->auth_zones; zone; zone = zone->next)
-		  if (in_zone(zone, daemon->namebuff, NULL))
-		    {
-		      auth_dns = 1;
-		      local_auth = 1;
-		      break;
-		    }
+		  {
+		    char *cut;
+		    
+		    if (in_zone(zone, daemon->namebuff, &cut))
+		      {
+			if (qtype != T_DS || cut)
+			  {
+			    auth_dns = 1;
+			    local_auth = 1;
+			  }
+			break;
+		      }
+		  }
 #endif
 	      
 	      norebind = domain_no_rebind(daemon->namebuff);
@@ -3023,8 +3057,9 @@ static struct frec *lookup_frec(char *target, int class, int rrtype, int id, int
       {
 	unsigned char *p = (unsigned char *)(header+1);
 	int hclass, hrrtype;
-		   
-	if (extract_name(header, f->stash_len, &p, target, 0, 4) != 1)
+
+	/* Case sensitive compare for DNS-0x20 encoding. */
+	if (extract_name(header, f->stash_len, &p, target, EXTR_NAME_NOCASE, 4) != 1)
 	  continue;
 		   
 	GETSHORT(hrrtype, p);

src/option.c

@@ -568,7 +568,7 @@ static struct {
   { LOPT_CMARK_ALST, ARG_DUP, "<connmark>[/<mask>][,<pattern>[/<pattern>...]]", gettext_noop("Set allowed DNS patterns for a connection-track mark."), NULL },
   { LOPT_SYNTH, ARG_DUP, "<domain>,<range>,[<prefix>]", gettext_noop("Specify a domain and address range for synthesised names"), NULL },
   { LOPT_SEC_VALID, OPT_DNSSEC_VALID, NULL, gettext_noop("Activate DNSSEC validation"), NULL },
-  { LOPT_TRUST_ANCHOR, ARG_DUP, "<domain>,[<class>],...", gettext_noop("Specify trust anchor key digest."), NULL },
+  { LOPT_TRUST_ANCHOR, ARG_DUP, "<domain>,[<class>,]...", gettext_noop("Specify trust anchor key digest."), NULL },
   { LOPT_DNSSEC_DEBUG, OPT_DNSSEC_DEBUG, NULL, gettext_noop("Disable upstream checking for DNSSEC debugging."), NULL },
   { LOPT_DNSSEC_CHECK, ARG_DUP, NULL, gettext_noop("Ensure answers without DNSSEC are in unsigned zones."), NULL },
   { LOPT_DNSSEC_TIME, OPT_DNSSEC_TIME, NULL, gettext_noop("Don't check DNSSEC signature timestamps until first cache-reload"), NULL },

src/rfc1035.c

@@ -16,16 +16,29 @@
 
 #include "dnsmasq.h"
 
+/* EXTR_NAME_EXTRACT -> extract name
+   EXTR_NAME_COMPARE -> compare name, case insensitive
+   EXTR_NAME_NOCASE -> compare name, case sensitive
+   EXTR_NAME_FLIP -> flip 0x20 bits in packet, controlled by bitmap in parm. name may be NULL 
+   
+   return = 0 -> error
+   return = 1 -> extract OK, compare OK, flip OK
+   return = 2 -> extract OK, compare failed.
+*/
 int extract_name(struct dns_header *header, size_t plen, unsigned char **pp, 
-		 char *name, int isExtract, int extrabytes)
+		 char *name, int func, unsigned int parm)
 {
   unsigned char *cp = (unsigned char *)name, *p = *pp, *p1 = NULL;
   unsigned int j, l, namelen = 0, hops = 0;
-  int retvalue = 1;
+  int retvalue = 1, case_insens = 1, isExtract = 0, flip = 0, extrabytes = (int)parm;
+  
+  if (func == EXTR_NAME_EXTRACT)
+    isExtract = 1, *cp = 0;
+  else if (func == EXTR_NAME_NOCASE)
+    case_insens = 0;
+  else if (func == EXTR_NAME_FLIP)
+    flip = 1, extrabytes = 0;
   
-  if (isExtract)
-    *cp = 0;
-
   while (1)
     { 
       unsigned int label_type;
@@ -46,7 +59,7 @@ int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
 		cp--;
 	      *cp = 0; /* terminate: lose final period */
 	    }
-	  else if (*cp != 0)
+	  else if (!flip && *cp != 0)
 	    retvalue = 2;
 	  
 	  if (p1) /* we jumped via compression */
@@ -85,7 +98,7 @@ int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
 	  if (!CHECK_LEN(header, p, plen, l))
 	    return 0;
 	  
-	  for(j=0; j<l; j++, p++)
+	  for (j=0; j<l; j++, p++)
 	    if (isExtract)
 	      {
 		unsigned char c = *p;
@@ -98,6 +111,18 @@ int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
 		else
 		  *cp++ = c; 
 	      }
+	    else if (flip)
+	      {
+		unsigned char c = *p;
+
+		/* parm is unsigned. We only flip up to the first 32 alpha-chars. */
+		if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
+		  {
+		    if (parm & 1)
+		      *p ^= 0x20;
+		    parm >>= 1;
+		  }
+	      }
 	    else 
 	      {
 		unsigned char c1 = *cp, c2 = *p;
@@ -107,15 +132,15 @@ int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
 		else 
 		  {
 		    cp++;
-		    if (c1 >= 'A' && c1 <= 'Z')
-		      c1 += 'a' - 'A';
 
 		    if (c1 == NAME_ESCAPE)
 		      c1 = (*cp++)-1;
+		    else if (case_insens && c1 >= 'A' && c1 <= 'Z')
+		      c1 += 'a' - 'A';
 		    
-		    if (c2 >= 'A' && c2 <= 'Z')
+		    if (case_insens && c2 >= 'A' && c2 <= 'Z')
 		      c2 += 'a' - 'A';
-		     
+		    
 		    if (c1 != c2)
 		      retvalue =  2;
 		  }
@@ -123,7 +148,7 @@ int extract_name(struct dns_header *header, size_t plen, unsigned char **pp,
 	    
 	  if (isExtract)
 	    *cp++ = '.';
-	  else if (*cp != 0 && *cp++ != '.')
+	  else if (!flip && *cp != 0 && *cp++ != '.')
 	    retvalue = 2;
 	}
       else
@@ -399,7 +424,7 @@ int do_doctor(struct dns_header *header, size_t qlen, char *namebuff)
       if (i == ntohs(header->ancount) && !(p = skip_section(p, ntohs(header->nscount), header, qlen)))
 	return done;
       
-      if (!extract_name(header, qlen, &p, namebuff, 1, 10))
+      if (!extract_name(header, qlen, &p, namebuff, EXTR_NAME_EXTRACT, 10))
 	return done; /* bad packet */
       
       GETSHORT(qtype, p); 
@@ -480,7 +505,7 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
   
   for (i = 0; i < ntohs(header->nscount); i++)
     {
-      if (!extract_name(header, qlen, &p, daemon->workspacename, 1, 0))
+      if (!extract_name(header, qlen, &p, daemon->workspacename, EXTR_NAME_EXTRACT, 0))
 	return 0; /* bad packet */
       
       GETSHORT(qtype, p); 
@@ -509,7 +534,7 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
 	      
 	      for (j = 0; j < 2; j++) /* MNAME, RNAME */
 		{
-		  if (!extract_name(header, qlen, &p, daemon->workspacename, 1, 0))
+		  if (!extract_name(header, qlen, &p, daemon->workspacename, EXTR_NAME_EXTRACT, 0))
 		    {
 		      if (!no_cache)
 			blockdata_free(addr.rrblock.rrdata);
@@ -660,7 +685,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 
   namep = p = (unsigned char *)(header+1);
   
-  if (ntohs(header->qdcount) != 1 || !extract_name(header, qlen, &p, name, 1, 4))
+  if (ntohs(header->qdcount) != 1 || !extract_name(header, qlen, &p, name, EXTR_NAME_EXTRACT, 4))
     return 2; /* bad packet */
   
   GETSHORT(qtype, p); 
@@ -684,7 +709,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 	  for (j = 0; j < ntohs(header->ancount); j++) 
 	    {
 	      int secflag = 0;
-	      if (!(res = extract_name(header, qlen, &p1, name, 0, 10)))
+	      if (!(res = extract_name(header, qlen, &p1, name, EXTR_NAME_COMPARE, 10)))
 		return 2; /* bad packet */
 	      
 	      GETSHORT(aqtype, p1); 
@@ -722,7 +747,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 		  if (aqtype == T_CNAME)
 		    log_query(secflag | F_CNAME | F_FORWARD | F_UPSTREAM, name, NULL, NULL, 0);
 		  
-		  if (!extract_name(header, qlen, &p1, name, 1, 0))
+		  if (!extract_name(header, qlen, &p1, name, EXTR_NAME_EXTRACT, 0))
 		    return 2;
 		  
 		  if (aqtype == T_CNAME)
@@ -800,7 +825,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 	{
 	  int secflag = 0;
 	  
-	  if (!(res = extract_name(header, qlen, &p1, name, 0, 10)))
+	  if (!(res = extract_name(header, qlen, &p1, name, EXTR_NAME_COMPARE, 10)))
 	    return 2; /* bad packet */
 	  
 	  GETSHORT(aqtype, p1); 
@@ -862,7 +887,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 		}
 	      
 	      namep = p1;
-	      if (!extract_name(header, qlen, &p1, name, 1, 0))
+	      if (!extract_name(header, qlen, &p1, name, EXTR_NAME_EXTRACT, 0))
 		return 2;
 	      
 	      if (qtype != T_CNAME)
@@ -932,7 +957,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 			      /* Name, extract it then re-encode. */
 			      int len;
 			      
-			      if (!extract_name(header, qlen, &p1, name, 1, 0))
+			      if (!extract_name(header, qlen, &p1, name, EXTR_NAME_EXTRACT, 0))
 				{
 				  blockdata_free(addr.rrblock.rrdata);
 				  return 2;
@@ -965,7 +990,7 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 			} while (desc != -1);
 		      
 		      /* we overwrote the original name, so get it back here. */
-		      if (!extract_name(header, qlen, &tmp, name, 1, 0))
+		      if (!extract_name(header, qlen, &tmp, name, EXTR_NAME_EXTRACT, 0))
 			{
 			  blockdata_free(addr.rrblock.rrdata);
 			  return 2;
@@ -1127,7 +1152,7 @@ void report_addresses(struct dns_header *header, size_t len, u32 mark)
     {
       int aqtype, aqclass, ardlen;
       
-      if (!extract_name(header, len, &p, daemon->namebuff, 1, 10))
+      if (!extract_name(header, len, &p, daemon->namebuff, EXTR_NAME_EXTRACT, 10))
 	return;
       
       if (!CHECK_LEN(header, p, len, 10))
@@ -1145,7 +1170,7 @@ void report_addresses(struct dns_header *header, size_t len, u32 mark)
 	{
 	  if (aqtype == T_CNAME)
 	    {
-	      if (!extract_name(header, len, &p, daemon->workspacename, 1, 0))
+	      if (!extract_name(header, len, &p, daemon->workspacename, EXTR_NAME_EXTRACT, 0))
 		return;
 	      if (safe_name(daemon->namebuff) && safe_name(daemon->workspacename))
 		ubus_event_bcast_connmark_allowlist_resolved(mark, daemon->namebuff, daemon->workspacename, attl);
@@ -1195,7 +1220,7 @@ unsigned int extract_request(struct dns_header *header, size_t qlen, char *name,
   if (!(header->hb3 & HB3_QR) && (ntohs(header->ancount) != 0 || ntohs(header->nscount) != 0))
     return 0; /* non-standard query. */
   
-  if (!extract_name(header, qlen, &p, name, 1, 4))
+  if (!extract_name(header, qlen, &p, name, EXTR_NAME_EXTRACT, 4))
     return 0; /* bad packet */
    
   GETSHORT(qtype, p); 
@@ -1309,7 +1334,7 @@ static int check_bad_address(struct dns_header *header, size_t qlen, struct bogu
 
   for (i = ntohs(header->ancount); i != 0; i--)
     {
-      if (name && !extract_name(header, qlen, &p, name, 1, 10))
+      if (name && !extract_name(header, qlen, &p, name, EXTR_NAME_EXTRACT, 10))
 	return 0; /* bad packet */
 
       if (!name && !(p = skip_name(p, header, qlen, 10)))
@@ -1559,7 +1584,7 @@ static unsigned long crec_ttl(struct crec *crecp, time_t now)
     return daemon->max_ttl;
 }
 
-static int cache_validated(const struct crec *crecp)
+static int cache_not_validated(const struct crec *crecp)
 {
   return (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK));
 }
@@ -1619,7 +1644,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
   nameoffset = p - (unsigned char *)header;
   
   /* now extract name as .-concatenated string into name */
-  if (!extract_name(header, qlen, &p, name, 1, 4))
+  if (!extract_name(header, qlen, &p, name, EXTR_NAME_EXTRACT, 4))
     return 0; /* bad packet */
   
   GETSHORT(qtype, p); 
@@ -1660,7 +1685,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 	
 	/* If the client asked for DNSSEC  don't use cached data. */
 	if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
-	    (rd_bit && (!do_bit || cache_validated(crecp))))
+	    (rd_bit && (!do_bit || cache_not_validated(crecp))))
 	  {
 	    if (crecp->flags & F_CONFIG || qtype == T_CNAME)
 	      ans = 1;
@@ -1819,7 +1844,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 		 the zone is unsigned, which implies that we're doing
 		 validation. */
 	      if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
-		  (rd_bit && (!do_bit || cache_validated(crecp)) ))
+		  (rd_bit && (!do_bit || cache_not_validated(crecp)) ))
 		{
 		  do 
 		    { 
@@ -1975,7 +2000,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 	      
 	      /* If the client asked for DNSSEC  don't use cached data. */
 	      if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
-		  (rd_bit && (!do_bit || cache_validated(crecp)) ))
+		  (rd_bit && (!do_bit || cache_not_validated(crecp)) ))
 		do
 		  { 
 		    int stale_flag = 0;
@@ -2157,19 +2182,19 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
       
       if (!ans)
 	{
-	  if ((crecp = cache_find_by_name(NULL, name, now, F_RR | F_NXDOMAIN)) &&
-	      rd_bit && (!do_bit || cache_validated(crecp)))
+	  if ((crecp = cache_find_by_name(NULL, name, now, F_RR | F_NXDOMAIN)) && rd_bit)
 	    do
 	      {
 		int flags = crecp->flags;
 		unsigned short rrtype;
-		
+
 		if (flags & F_KEYTAG)
 		  rrtype = crecp->addr.rrblock.rrtype;
 		else
 		  rrtype = crecp->addr.rrdata.rrtype;
 		
-		if ((flags & F_NXDOMAIN) || rrtype == qtype)
+		if (((flags & F_NXDOMAIN) || rrtype == qtype) &&
+		    (!do_bit || cache_not_validated(crecp)))
 		  {
 		    char *rrdata = NULL;
 		    unsigned short rrlen = 0;
@@ -2232,14 +2257,15 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 	}
       
       
-      if (qtype != T_ANY && !ans && rr_on_list(daemon->filter_rr, qtype))
+      if (qtype != T_ANY && !ans && rr_on_list(daemon->filter_rr, qtype) && !do_bit)
 	{
 	  /* We don't have a cached answer and when we get an answer from upstream we're going to
 	     filter it anyway. If we have a cached answer for the domain for another RRtype then
 	     that may be enough to tell us if the answer should be NODATA and save the round trip.
 	     Cached NXDOMAIN has already been handled, so here we look for any record for the domain,
 	     since its existence allows us to return a NODATA answer. Note that we never set the AD flag,
-	     since we didn't authenticate the record. */
+	     since we didn't authenticate the record; this doesn't work if we want auth data, so
+	     don't use this shortcut in that case. */
 	  
 	  if (cache_find_by_name(NULL, name, now, F_IPV4 | F_IPV6 | F_RR | F_CNAME))
 	    {