CHANGELOG update.

Some CNAMES left the value of ->uid undefined.

Since there are now special values if this, for CNAMES
to interface names, that could cause a crash
if the undefined value hit the special value.

Also ensure that the special value can't arise
when the uid is encoding the source of an F_CONFIG
record, in case there's a CNAME to it.

CHANGELOG

@@ -67,7 +67,20 @@ version 2.69
 	    Add --servers-file. Allows dynamic update of upstream servers 
 	    full access to configuration. 
 
- 	    
+	    Add --local-service. Accept DNS queries only from hosts 
+            whose address is on a local subnet, ie a subnet for which 
+            an interface exists on the server. This option
+            only has effect if there are no --interface --except-interface,
+            --listen-address or --auth-server options. It is intended 
+            to be set as a default on installation, to allow
+            unconfigured installations to be useful but also safe from 
+	    being used for DNS amplification attacks.
+
+	    Fix crashes in cache_get_cname_target() when dangling CNAMEs
+	    encountered. Thanks to Andy and the rt-n56u project for
+	    find this and helping to chase it down.
+
+
 version 2.68
             Use random addresses for DHCPv6 temporary address
             allocations, instead of algorithmically determined stable

bld/pkg-wrapper

@@ -14,8 +14,11 @@ if grep "^\#[[:space:]]*define[[:space:]]*$search" config.h >/dev/null 2>&1 || \
 
     if [ $op = "--copy" ]; then
 	pkg="$*"
+    elif grep "^\#[[:space:]]*define[[:space:]]*${search}_STATIC" config.h >/dev/null 2>&1 || \
+	      echo $in | grep ${search}_STATIC >/dev/null 2>&1; then
+	pkg=`$pkg  --static $op $*`
     else
-	pkg=`$pkg $op $*` 
+	pkg=`$pkg $op $*`
     fi
 
     if grep "^\#[[:space:]]*define[[:space:]]*${search}_STATIC" config.h >/dev/null 2>&1 || \

debian/changelog

@@ -1,6 +1,12 @@
 dnsmasq (2.69-1) unstable; urgency=low
 
    * New upstream.
+   * Set --local-service. (closes: #732610)
+     This tells dnsmasq to ignore DNS requests that don't come from a local network.
+     It's automatically ignored if  --interface --except-interface, --listen-address
+     or --auth-server exist in the configuration, so for most installations, it will
+     have no effect, but for otherwise-unconfigured installations, it stops dnsmasq
+     from being vulnerable to DNS-reflection attacks.
 
  -- Simon Kelley <simon@thekelleys.org.uk>  Tue, 4 Feb 2014 16:28:12 +0000
 

debian/init

@@ -90,6 +90,14 @@ if [ ! "$DNSMASQ_USER" ]; then
    DNSMASQ_USER="dnsmasq"
 fi
 
+# This tells dnsmasq to ignore DNS requests that don't come from a local network.
+# It's automatically ignored if  --interface --except-interface, --listen-address 
+# or --auth-server exist in the configuration, so for most installations, it will
+# have no effect, but for otherwise-unconfigured installations, it stops dnsmasq
+# from being vulnerable to DNS-reflection attacks.
+
+DNSMASQ_OPTS="$DNSMASQ_OPTS --local-service"
+
 start()
 {
         # Return

man/dnsmasq.8

@@ -208,6 +208,14 @@ resolve in the global DNS to a A and/or AAAA record which points to
 the address dnsmasq is listening on. When an interface is specified,
 it may be qualified with "/4" or "/6" to specify only the IPv4 or IPv6
 addresses associated with the interface.
+.TP
+.B --local-service
+Accept DNS queries only from hosts whose address is on a local subnet,
+ie a subnet for which an interface exists on the server. This option
+only has effect is there are no --interface --except-interface,
+--listen-address or --auth-server options. It is intended to be set as
+a default on installation, to allow unconfigured installations to be
+useful but also safe from being used for DNS amplification attacks.
 .TP 
 .B \-2, --no-dhcp-interface=<interface name>
 Do not provide DHCP or TFTP on the specified interface, but do provide DNS service.
@@ -599,7 +607,15 @@ clients unable to do validation, use of the AD bit set by dnsmasq is useful, pro
 the dnsmasq server and the client is trusted. Dnsmasq must be compiled with HAVE_DNSSEC enabled, and DNSSEC
 trust anchors provided, see 
 .B --trust-anchor.
-Because the DNSSEC validation process uses the cache, it is not permitted to reduce the cache size below the default when DNSSEC is enabled.
+Because the DNSSEC validation process uses the cache, it is not
+permitted to reduce the cache size below the default when DNSSEC is
+enabled. The nameservers upstream of dnsmasq must be DNSSEC-capable,
+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. In the default mode, this menas that all replies will be
+marked as untrusted. If 
+.B --dnssec-check-unsigned
+is set and the upstream servers don't support DNSSEC, then DNS service will be entirely broken.
 .TP
 .B --trust-anchor=[<class>],<domain>,<key-tag>,<algorithm>,<digest-type>,<digest>
 Provide DS records to act a trust anchors for DNSSEC
@@ -615,7 +631,10 @@ legitimate: they are assumed to be valid and passed on (without the
 attacker forging unsigned replies for signed DNS zones, but it is
 fast. If this flag is set, dnsmasq will check the zones of unsigned
 replies, to ensure that unsigned replies are allowed in those
-zones. The cost of this is more upstream queries and slower performance.
+zones. The cost of this is more upstream queries and slower
+performance. See also the warning about upstream servers in the
+section on 
+.B --dnssec
 .TP
 .B --proxy-dnssec
 Copy the DNSSEC Authenticated Data bit from upstream servers to downstream clients and cache it.  This is an 
@@ -754,7 +773,7 @@ or from /etc/ethers will be served. A static-only subnet with address
 all zeros may be used as a "catch-all" address to enable replies to all
 Information-request packets on a subnet which is provided with
 stateless DHCPv6, ie
-.B --dhcp=range=::,static
+.B --dhcp-range=::,static
 
 For IPv4, the <mode> may be 
 .B proxy
@@ -1843,7 +1862,7 @@ which has tags will be used in preference  to an untagged
 .B dhcp-option,
 provided that _all_ the tags match somewhere in the
 set collected as described above. The prefix '!' on a tag means 'not'
-so --dhcp=option=tag:!purple,3,1.2.3.4 sends the option when the
+so --dhcp-option=tag:!purple,3,1.2.3.4 sends the option when the
 tag purple is not in the set of valid tags. (If using this in a
 command line rather than a configuration file, be sure to escape !,
 which is a shell metacharacter)

src/cache.c

@@ -24,7 +24,6 @@ static struct crec *new_chain = NULL;
 static int cache_inserted = 0, cache_live_freed = 0, insert_error;
 static union bigname *big_free = NULL;
 static int bignames_left, hash_size;
-static int uid = 1;
 
 /* type->string mapping: this is also used by the name-hash function as a mixing table. */
 static const struct {
@@ -73,6 +72,19 @@ static void cache_link(struct crec *crecp);
 static void rehash(int size);
 static void cache_hash(struct crec *crecp);
 
+static unsigned int next_uid(void)
+{
+  static unsigned int uid = 0;
+
+  uid++;
+  
+  /* uid == 0 used to indicate CNAME to interface name. */
+  if (uid == SRC_INTERFACE)
+    uid++;
+  
+  return uid;
+}
+
 void cache_init(void)
 {
   struct crec *crecp;
@@ -88,7 +100,7 @@ void cache_init(void)
 	{
 	  cache_link(crecp);
 	  crecp->flags = 0;
-	  crecp->uid = uid++;
+	  crecp->uid = next_uid();
 	}
     }
   
@@ -192,10 +204,7 @@ static void cache_free(struct crec *crecp)
 {
   crecp->flags &= ~F_FORWARD;
   crecp->flags &= ~F_REVERSE;
-  crecp->uid = uid++; /* invalidate CNAMES pointing to this. */
-
-  if (uid == -1)
-    uid++;
+  crecp->uid = next_uid(); /* invalidate CNAMES pointing to this. */
 
   if (cache_tail)
     cache_tail->next = crecp;
@@ -256,7 +265,7 @@ char *cache_get_name(struct crec *crecp)
 
 char *cache_get_cname_target(struct crec *crecp)
 {
-  if (crecp->addr.cname.uid != -1)
+  if (crecp->addr.cname.uid != SRC_INTERFACE)
     return cache_get_name(crecp->addr.cname.target.cache);
 
   return crecp->addr.cname.target.int_name->name;
@@ -289,7 +298,7 @@ struct crec *cache_enumerate(int init)
 
 static int is_outdated_cname_pointer(struct crec *crecp)
 {
-  if (!(crecp->flags & F_CNAME) || crecp->addr.cname.uid == -1)
+  if (!(crecp->flags & F_CNAME) || crecp->addr.cname.uid == SRC_INTERFACE)
     return 0;
   
   /* NB. record may be reused as DS or DNSKEY, where uid is 
@@ -774,13 +783,14 @@ static void add_hosts_cname(struct crec *target)
 	crec->name.namep = a->alias;
 	crec->addr.cname.target.cache = target;
 	crec->addr.cname.uid = target->uid;
+	crec->uid = next_uid();
 	cache_hash(crec);
 	add_hosts_cname(crec); /* handle chains */
       }
 }
   
 static void add_hosts_entry(struct crec *cache, struct all_addr *addr, int addrlen, 
-			    int index, struct crec **rhash, int hashsz)
+			    unsigned int index, struct crec **rhash, int hashsz)
 {
   struct crec *lookup = cache_find_by_name(NULL, cache_get_name(cache), 0, cache->flags & (F_IPV4 | F_IPV6));
   int i, nameexists = 0;
@@ -884,7 +894,7 @@ static int gettok(FILE *f, char *token)
     }
 }
 
-static int read_hostsfile(char *filename, int index, int cache_size, struct crec **rhash, int hashsz)
+static int read_hostsfile(char *filename, unsigned int index, int cache_size, struct crec **rhash, int hashsz)
 {  
   FILE *f = fopen(filename, "r");
   char *token = daemon->namebuff, *domain_suffix = NULL;
@@ -1034,7 +1044,8 @@ void cache_reload(void)
 	  cache->flags = F_FORWARD | F_NAMEP | F_CNAME | F_IMMORTAL | F_CONFIG;
 	  cache->name.namep = a->alias;
 	  cache->addr.cname.target.int_name = intr;
-	  cache->addr.cname.uid = -1;
+	  cache->addr.cname.uid = SRC_INTERFACE;
+	  cache->uid = next_uid();
 	  cache_hash(cache);
 	  add_hosts_cname(cache); /* handle chains */
 	}
@@ -1070,7 +1081,7 @@ void cache_reload(void)
 	  {
 	    cache->name.namep = nl->name;
 	    cache->flags = F_HOSTS | F_IMMORTAL | F_FORWARD | F_REVERSE | F_IPV4 | F_NAMEP | F_CONFIG;
-	    add_hosts_entry(cache, (struct all_addr *)&hr->addr, INADDRSZ, 0, (struct crec **)daemon->packet, revhashsz);
+	    add_hosts_entry(cache, (struct all_addr *)&hr->addr, INADDRSZ, SRC_CONFIG, (struct crec **)daemon->packet, revhashsz);
 	  }
 #ifdef HAVE_IPV6
 	if (!IN6_IS_ADDR_UNSPECIFIED(&hr->addr6) &&
@@ -1078,7 +1089,7 @@ void cache_reload(void)
 	  {
 	    cache->name.namep = nl->name;
 	    cache->flags = F_HOSTS | F_IMMORTAL | F_FORWARD | F_REVERSE | F_IPV6 | F_NAMEP | F_CONFIG;
-	    add_hosts_entry(cache, (struct all_addr *)&hr->addr6, IN6ADDRSZ, 0, (struct crec **)daemon->packet, revhashsz);
+	    add_hosts_entry(cache, (struct all_addr *)&hr->addr6, IN6ADDRSZ, SRC_CONFIG, (struct crec **)daemon->packet, revhashsz);
 	  }
 #endif
       }
@@ -1091,7 +1102,7 @@ void cache_reload(void)
     }
     
   if (!option_bool(OPT_NO_HOSTS))
-    total_size = read_hostsfile(HOSTSFILE, 0, total_size, (struct crec **)daemon->packet, revhashsz);
+    total_size = read_hostsfile(HOSTSFILE, SRC_HOSTS, total_size, (struct crec **)daemon->packet, revhashsz);
   	   
   daemon->addn_hosts = expand_filelist(daemon->addn_hosts);
   for (ah = daemon->addn_hosts; ah; ah = ah->next)
@@ -1155,6 +1166,7 @@ static void add_dhcp_cname(struct crec *target, time_t ttd)
 	    aliasc->name.namep = a->alias;
 	    aliasc->addr.cname.target.cache = target;
 	    aliasc->addr.cname.uid = target->uid;
+	    aliasc->uid = next_uid();
 	    cache_hash(aliasc);
 	    add_dhcp_cname(aliasc, ttd);
 	  }
@@ -1242,7 +1254,7 @@ void cache_add_dhcp_entry(char *host_name, int prot,
 	crec->ttd = ttd;
       crec->addr.addr = *host_address;
       crec->name.namep = host_name;
-      crec->uid = uid++;
+      crec->uid = next_uid();
       cache_hash(crec);
 
       add_dhcp_cname(crec, ttd);
@@ -1368,11 +1380,13 @@ void dump_cache(time_t now)
     }
 }
 
-char *record_source(int index)
+char *record_source(unsigned int index)
 {
   struct hostsfile *ah;
 
-  if (index == 0)
+  if (index == SRC_CONFIG)
+    return "config";
+  else if (index == SRC_HOSTS)
     return HOSTSFILE;
 
   for (ah = daemon->addn_hosts; ah; ah = ah->next)

src/config.h

@@ -18,7 +18,7 @@
 #define MAX_PROCS 20 /* max no children for TCP requests */
 #define CHILD_LIFETIME 150 /* secs 'till terminated (RFC1035 suggests > 120s) */
 #define EDNS_PKTSZ 4096 /* default max EDNS.0 UDP packet from RFC5625 */
-#define KEYBLOCK_LEN 35 /* choose to mininise fragmentation when storing DNSSEC keys */
+#define KEYBLOCK_LEN 40 /* choose to mininise fragmentation when storing DNSSEC keys */
 #define DNSSEC_WORK 50 /* Max number of queries to validate one question */
 #define TIMEOUT 10 /* drop UDP queries after TIMEOUT seconds */
 #define FORWARD_TEST 50 /* try all servers every 50 queries */

src/dnsmasq.c

@@ -661,6 +661,9 @@ int main (int argc, char **argv)
 	my_syslog(LOG_INFO, _("DBus support enabled: bus connection pending"));
     }
 #endif
+
+  if (option_bool(OPT_LOCAL_SERVICE))
+    my_syslog(LOG_INFO, _("DNS service limited to local subnets"));
   
 #ifdef HAVE_DNSSEC
   if (option_bool(OPT_DNSSEC_VALID))

src/dnsmasq.h

@@ -233,7 +233,8 @@ struct event_desc {
 #define OPT_DNSSEC_PERMISS 46
 #define OPT_DNSSEC_DEBUG   47
 #define OPT_DNSSEC_NO_SIGN 48 
-#define OPT_LAST           49
+#define OPT_LOCAL_SERVICE  49
+#define OPT_LAST           50
 
 /* extra flags for my_syslog, we use a couple of facilities since they are known 
    not to occupy the same bits as priorities, no matter how syslog.h is set up. */
@@ -366,7 +367,7 @@ struct crec {
 	struct crec *cache;
 	struct interface_name *int_name;
       } target;
-      int uid; /* -1 if union is interface-name */
+      unsigned int uid; /* 0 if union is interface-name */
     } cname;
     struct {
       struct blockdata *keydata;
@@ -387,7 +388,7 @@ struct crec {
   } addr;
   time_t ttd; /* time to die */
   /* used as class if DNSKEY/DS/RRSIG, index to source for F_HOSTS */
-  int uid; 
+  unsigned int uid; 
   unsigned short flags;
   union {
     char sname[SMALLDNAME];
@@ -426,6 +427,12 @@ struct crec {
 #define F_SECSTAT   (1u<<24)
 #define F_NO_RR     (1u<<25)
 
+/* Values of uid in crecs with F_CONFIG bit set. */
+#define SRC_INTERFACE 0
+#define SRC_CONFIG    1
+#define SRC_HOSTS     2
+#define SRC_AH        3
+
 
 /* struct sockaddr is not large enough to hold any address,
    and specifically not big enough to hold an IPv6 address.
@@ -524,7 +531,7 @@ struct hostsfile {
   struct hostsfile *next;
   int flags;
   char *fname;
-  int index; /* matches to cache entries for logging */
+  unsigned int index; /* matches to cache entries for logging */
 };
 
 
@@ -966,6 +973,7 @@ extern struct daemon {
   pid_t tcp_pids[MAX_PROCS];
   struct randfd randomsocks[RANDOM_SOCKS];
   int v6pktinfo; 
+  struct addrlist *interface_addrs; /* list of all addresses/prefix lengths associated with all local interfaces */
 
   /* DHCP state */
   int dhcpfd, helperfd, pxefd; 
@@ -1003,7 +1011,7 @@ extern struct daemon {
 /* cache.c */
 void cache_init(void);
 void log_query(unsigned int flags, char *name, struct all_addr *addr, char *arg); 
-char *record_source(int index);
+char *record_source(unsigned int index);
 char *querystr(char *desc, unsigned short type);
 struct crec *cache_find_by_addr(struct crec *crecp,
 				struct all_addr *addr, time_t now, 

src/dnssec.c

@@ -827,7 +827,7 @@ static int validate_rrset(time_t now, struct dns_header *header, size_t plen, in
 	  for (; crecp; crecp = cache_find_by_name(crecp, keyname, now, F_DNSKEY))
 	    if (crecp->addr.key.algo == algo && 
 		crecp->addr.key.keytag == key_tag &&
-		crecp->uid == class &&
+		crecp->uid == (unsigned int)class &&
 		verify(crecp->addr.key.keydata, crecp->addr.key.keylen, sig, sig_len, digest, hash->digest_size, algo))
 	      return (labels < name_labels) ? STAT_SECURE_WILDCARD : STAT_SECURE;
 	}
@@ -932,7 +932,7 @@ int dnssec_validate_by_ds(time_t now, struct dns_header *header, size_t plen, ch
 	  
 	  if (recp1->addr.ds.algo == algo && 
 	      recp1->addr.ds.keytag == keytag &&
-	      recp1->uid == class &&
+	      recp1->uid == (unsigned int)class &&
 	      (hash = hash_find(ds_digest_name(recp1->addr.ds.digest))) &&
 	      hash_init(hash, &ctx, &digest))
 	    
@@ -1918,14 +1918,14 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
 int dnssec_chase_cname(time_t now, struct dns_header *header, size_t plen, char *name, char *keyname)
 {
   unsigned char *p = (unsigned char *)(header+1);
-  int type, class, qtype, qclass, rdlen, j, rc;
+  int type, class, qclass, rdlen, j, rc;
   int cname_count = CNAME_CHAIN;
 
   /* Get question */
   if (!extract_name(header, plen, &p, name, 1, 4))
     return STAT_BOGUS;
   
-  GETSHORT(qtype, p);
+  p +=2; /* type */
   GETSHORT(qclass, p);
 
   while (1)

src/forward.c

@@ -278,7 +278,7 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
 	  blockdata_retrieve(forward->stash, forward->stash_len, (void *)header);
 	  plen = forward->stash_len;
 	  
-	  if (forward->sentto->addr.sa.sa_family) 
+	  if (forward->sentto->addr.sa.sa_family == AF_INET) 
 	    log_query(F_DNSSEC | F_IPV4, "retry", (struct all_addr *)&forward->sentto->addr.in.sin_addr, "dnssec");
 #ifdef HAVE_IPV6
 	  else
@@ -299,7 +299,7 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
 	  
 	  while (sendto(fd, (char *)header, plen, 0,
 			&forward->sentto->addr.sa,
-			    sa_len(&forward->sentto->addr)) == -1 && retry_send());
+			sa_len(&forward->sentto->addr)) == -1 && retry_send());
 	  
 	  return 1;
 	}
@@ -1076,11 +1076,60 @@ void receive_query(struct listener *listen, time_t now)
     return;
   
   source_addr.sa.sa_family = listen->family;
+  
+  if (listen->family == AF_INET)
+    {
+       /* Source-port == 0 is an error, we can't send back to that. 
+	  http://www.ietf.org/mail-archive/web/dnsop/current/msg11441.html */
+      if (source_addr.in.sin_port == 0)
+	return;
+    }
 #ifdef HAVE_IPV6
-  if (listen->family == AF_INET6)
-    source_addr.in6.sin6_flowinfo = 0;
+  else
+    {
+      /* Source-port == 0 is an error, we can't send back to that. */
+      if (source_addr.in6.sin6_port == 0)
+	return;
+      source_addr.in6.sin6_flowinfo = 0;
+    }
 #endif
-
+  
+  /* We can be configured to only accept queries from at-most-one-hop-away addresses. */
+  if (option_bool(OPT_LOCAL_SERVICE))
+    {
+      struct addrlist *addr;
+#ifdef HAVE_IPV6
+      if (listen->family == AF_INET6) 
+	{
+	  for (addr = daemon->interface_addrs; addr; addr = addr->next)
+	    if ((addr->flags & ADDRLIST_IPV6) &&
+		is_same_net6(&addr->addr.addr.addr6, &source_addr.in6.sin6_addr, addr->prefixlen))
+	      break;
+	}
+      else
+#endif
+	{
+	  struct in_addr netmask;
+	  for (addr = daemon->interface_addrs; addr; addr = addr->next)
+	    {
+	      netmask.s_addr = 0xffffffff << (32 - addr->prefixlen);
+	      if (!(addr->flags & ADDRLIST_IPV6) &&
+		  is_same_net(addr->addr.addr.addr4, source_addr.in.sin_addr, netmask))
+		break;
+	    }
+	}
+      if (!addr)
+	{
+	  static int warned = 0;
+	  if (!warned)
+	    {
+	      my_syslog(LOG_WARNING, _("Ignoring query from non-local network"));
+	      warned = 1;
+	    }
+	  return;
+	}
+    }
+		
   if (check_dst)
     {
       struct ifreq ifr;
@@ -1544,6 +1593,37 @@ unsigned char *tcp_request(int confd, time_t now,
   
   if (getpeername(confd, (struct sockaddr *)&peer_addr, &peer_len) == -1)
     return packet;
+  
+  /* We can be configured to only accept queries from at-most-one-hop-away addresses. */
+  if (option_bool(OPT_LOCAL_SERVICE))
+    {
+      struct addrlist *addr;
+#ifdef HAVE_IPV6
+      if (peer_addr.sa.sa_family == AF_INET6) 
+	{
+	  for (addr = daemon->interface_addrs; addr; addr = addr->next)
+	    if ((addr->flags & ADDRLIST_IPV6) &&
+		is_same_net6(&addr->addr.addr.addr6, &peer_addr.in6.sin6_addr, addr->prefixlen))
+	      break;
+	}
+      else
+#endif
+	{
+	  struct in_addr netmask;
+	  for (addr = daemon->interface_addrs; addr; addr = addr->next)
+	    {
+	      netmask.s_addr = 0xffffffff << (32 - addr->prefixlen);
+	      if (!(addr->flags & ADDRLIST_IPV6) && 
+		  is_same_net(addr->addr.addr.addr4, peer_addr.in.sin_addr, netmask))
+		break;
+	    }
+	}
+      if (!addr)
+	{
+	  my_syslog(LOG_WARNING, _("Ignoring query from non-local network"));
+	  return packet;
+	}
+    }
 
   while (1)
     {

src/network.c

@@ -268,7 +268,40 @@ static int iface_allowed(struct iface_param *param, int if_index, char *label,
   
   if (!label)
     label = ifr.ifr_name;
+ 
+  /* maintain a list of all addresses on all interfaces for --local-service option */
+  if (option_bool(OPT_LOCAL_SERVICE))
+    {
+      struct addrlist *al;
 
+      if (param->spare)
+	{
+	  al = param->spare;
+	  param->spare = al->next;
+	}
+      else
+	al = whine_malloc(sizeof(struct addrlist));
+      
+      if (al)
+	{
+	  al->next = daemon->interface_addrs;
+	  daemon->interface_addrs = al;
+	  al->prefixlen = prefixlen;
+	  
+	  if (addr->sa.sa_family == AF_INET)
+	    {
+	      al->addr.addr.addr4 = addr->in.sin_addr;
+	      al->flags = 0;
+	    }
+#ifdef HAVE_IPV6
+	  else
+	    {
+	      al->addr.addr.addr6 = addr->in6.sin6_addr;
+	      al->flags = ADDRLIST_IPV6;
+	    } 
+#endif
+	}
+    }
   
 #ifdef HAVE_IPV6
   if (addr->sa.sa_family != AF_INET6 || !IN6_IS_ADDR_LINKLOCAL(&addr->in6.sin6_addr))
@@ -565,6 +598,15 @@ int enumerate_interfaces(int reset)
       intname->addr = NULL;
     }
 
+  /* Remove list of addresses of local interfaces */
+  for (addr = daemon->interface_addrs; addr; addr = tmp)
+    {
+      tmp = addr->next;
+      addr->next = spare;
+      spare = addr;
+    }
+  daemon->interface_addrs = NULL;
+  
 #ifdef HAVE_AUTH
   /* remove addresses stored against auth_zone subnets, but not 
    ones configured as address literals */
@@ -1528,7 +1570,8 @@ void newaddress(time_t now)
 {
   (void)now;
   
-  if (option_bool(OPT_CLEVERBIND) || daemon->doing_dhcp6 || daemon->relay6 || daemon->doing_ra)
+  if (option_bool(OPT_CLEVERBIND) || option_bool(OPT_LOCAL_SERVICE) ||
+      daemon->doing_dhcp6 || daemon->relay6 || daemon->doing_ra)
     enumerate_interfaces(0);
   
   if (option_bool(OPT_CLEVERBIND))

src/option.c

@@ -144,6 +144,7 @@ struct myoption {
 #define LOPT_REV_SERV     332
 #define LOPT_SERVERS_FILE 333
 #define LOPT_DNSSEC_CHECK 334
+#define LOPT_LOCAL_SERVICE 335
 
 #ifdef HAVE_GETOPT_LONG
 static const struct option opts[] =  
@@ -175,6 +176,7 @@ static const struct myoption opts[] =
     { "domain-suffix", 1, 0, 's' },
     { "interface", 1, 0, 'i' },
     { "listen-address", 1, 0, 'a' },
+    { "local-service", 0, 0, LOPT_LOCAL_SERVICE },
     { "bogus-priv", 0, 0, 'b' },
     { "bogus-nxdomain", 1, 0, 'B' },
     { "selfmx", 0, 0, 'e' },
@@ -448,6 +450,7 @@ static struct {
   { LOPT_QUIET_DHCP, OPT_QUIET_DHCP, NULL, gettext_noop("Do not log routine DHCP."), NULL },
   { LOPT_QUIET_DHCP6, OPT_QUIET_DHCP6, NULL, gettext_noop("Do not log routine DHCPv6."), NULL },
   { LOPT_QUIET_RA, OPT_QUIET_RA, NULL, gettext_noop("Do not log RA."), NULL },
+  { LOPT_LOCAL_SERVICE, OPT_LOCAL_SERVICE, NULL, gettext_noop("Accept queries only from directly-connected networks"), NULL },
   { 0, 0, NULL, NULL, NULL }
 }; 
 
@@ -1661,7 +1664,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
     case 'H': /* --addn-hosts */
       {
 	struct hostsfile *new = opt_malloc(sizeof(struct hostsfile));
-	static int hosts_index = 1;
+	static unsigned int hosts_index = SRC_AH;
 	new->fname = opt_string_alloc(arg);
 	new->index = hosts_index++;
 	new->flags = 0;
@@ -4017,10 +4020,11 @@ static int one_file(char *file, int hard_opt)
 /* expand any name which is a directory */
 struct hostsfile *expand_filelist(struct hostsfile *list)
 {
-  int i;
+  unsigned int i;
   struct hostsfile *ah;
 
-  for (i = 0, ah = list; ah; ah = ah->next)
+  /* find largest used index */
+  for (i = SRC_AH, ah = list; ah; ah = ah->next)
     {
       if (i <= ah->index)
 	i = ah->index + 1;
@@ -4457,6 +4461,11 @@ void read_opts(int argc, char **argv, char *compile_opts)
   else if (option_bool(OPT_DHCP_FQDN))
     die(_("there must be a default domain when --dhcp-fqdn is set"), NULL, EC_BADCONF);
 
+  /* If there's access-control config, then ignore --local-service, it's intended
+     as a system default to keep otherwise unconfigured installations safe. */
+  if (daemon->if_names || daemon->if_except || daemon->if_addrs || daemon->authserver)
+    reset_option_bool(OPT_LOCAL_SERVICE); 
+
   if (testmode)
     {
       fprintf(stderr, "dnsmasq: %s.\n", _("syntax check OK"));

src/rfc1035.c

@@ -1065,6 +1065,8 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 		      if (newc)
 			{
 			  newc->addr.cname.target.cache = NULL;
+			  /* anything other than zero, to avoid being mistaken for CNAME to interface-name */ 
+			  newc->addr.cname.uid = 1; 
 			  if (cpp)
 			    {
 			      cpp->addr.cname.target.cache = newc;
@@ -1456,7 +1458,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 {
   char *name = daemon->namebuff;
   unsigned char *p, *ansp, *pheader;
-  int qtype, qclass;
+  unsigned int qtype, qclass;
   struct all_addr addr;
   int nameoffset;
   unsigned short flag;
@@ -2016,7 +2018,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
 			    
 			    strcpy(name, cname_target);
 			    /* check if target interface_name */
-			    if (crecp->addr.cname.uid == -1)
+			    if (crecp->addr.cname.uid == SRC_INTERFACE)
 			      goto intname_restart;
 			    else
 			      goto cname_restart;

src/rfc2131.c

@@ -962,6 +962,8 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
     case DHCPDISCOVER:
       if (ignore || have_config(config, CONFIG_DISABLE))
 	{
+	  if (option_bool(OPT_QUIET_DHCP))
+	    return 0;
 	  message = _("ignored");
 	  opt = NULL;
 	}