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https://github.com/pi-hole/dnsmasq.git
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Fix confusion is server=/domain/# combined with server|address=/domain/....
The 2.86 domain matching rewrite failed to take into account the possibilty that server=/example.com/# could be combined with, for example address=/example.com/1.2.3.4 resulting in the struct server datastructure for the former getting passed to forward_query(), rapidly followed by a SEGV. This fix makes server=/example.com/# a fully fledged member of the priority list, which is now IPv6 addr, IPv4 addr, all zero return, resolvconf servers, upstream servers, no-data return Thanks to dl6er@dl6er.de for finding and characterising the bug.
This commit is contained in:
Simon Kelley
@@ -530,18 +530,18 @@ union mysockaddr {
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/* The actual values here matter, since we sort on them to get records in the order
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IPv6 addr, IPv4 addr, all zero return, no-data return, send upstream. */
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#define SERV_LITERAL_ADDRESS 1 /* addr is the answer, or NoDATA is the answer, depending on the next three flags */
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#define SERV_ALL_ZEROS 2 /* return all zeros for A and AAAA */
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#define SERV_4ADDR 4 /* addr is IPv4 */
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#define SERV_6ADDR 8 /* addr is IPv6 */
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#define SERV_HAS_SOURCE 16 /* source address defined */
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#define SERV_FOR_NODOTS 32 /* server for names with no domain part only */
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#define SERV_WARNED_RECURSIVE 64 /* avoid warning spam */
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#define SERV_FROM_DBUS 128 /* 1 if source is DBus */
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#define SERV_MARK 256 /* for mark-and-delete and log code */
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#define SERV_WILDCARD 512 /* domain has leading '*' */
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#define SERV_USE_RESOLV 1024 /* forward this domain in the normal way */
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IPv6 addr, IPv4 addr, all zero return, resolvconf servers, upstream server, no-data return */
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#define SERV_LITERAL_ADDRESS 1 /* addr is the answer, or NoDATA is the answer, depending on the next four flags */
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#define SERV_USE_RESOLV 2 /* forward this domain in the normal way */
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#define SERV_ALL_ZEROS 4 /* return all zeros for A and AAAA */
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#define SERV_4ADDR 8 /* addr is IPv4 */
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#define SERV_6ADDR 16 /* addr is IPv6 */
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#define SERV_HAS_SOURCE 32 /* source address defined */
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#define SERV_FOR_NODOTS 64 /* server for names with no domain part only */
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#define SERV_WARNED_RECURSIVE 128 /* avoid warning spam */
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#define SERV_FROM_DBUS 256 /* 1 if source is DBus */
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#define SERV_MARK 512 /* for mark-and-delete and log code */
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#define SERV_WILDCARD 1024 /* domain has leading '*' */
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#define SERV_FROM_RESOLV 2048 /* 1 for servers from resolv, 0 for command line. */
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#define SERV_FROM_FILE 4096 /* read from --servers-file */
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#define SERV_LOOP 8192 /* server causes forwarding loop */
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@@ -207,16 +207,16 @@ int lookup_domain(char *domain, int flags, int *lowout, int *highout)
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}
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}
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if (found)
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{
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/* We've matched a setting which says to use servers without a domain.
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Continue the search with empty query */
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if (daemon->serverarray[try]->flags & SERV_USE_RESOLV)
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crop_query = qlen;
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else if (filter_servers(try, flags, &nlow, &nhigh))
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if (found && filter_servers(try, flags, &nlow, &nhigh))
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/* We have a match, but it may only be (say) an IPv6 address, and
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if the query wasn't for an AAAA record, it's no good, and we need
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to continue generalising */
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{
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/* We've matched a setting which says to use servers without a domain.
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Continue the search with empty query */
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if (daemon->serverarray[nlow]->flags & SERV_USE_RESOLV)
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crop_query = qlen;
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else
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break;
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}
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}
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@@ -293,7 +293,7 @@ int filter_servers(int seed, int flags, int *lowout, int *highout)
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else
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{
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/* Now the servers are on order between low and high, in the order
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IPv6 addr, IPv4 addr, return zero for both, send upstream, no-data return.
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IPv6 addr, IPv4 addr, return zero for both, resolvconf servers, send upstream, no-data return.
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See which of those match our query in that priority order and narrow (low, high) */
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@@ -321,6 +321,13 @@ int filter_servers(int seed, int flags, int *lowout, int *highout)
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{
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nlow = i;
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/* Short to resolv.conf servers */
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for (i = nlow; i < nhigh && (daemon->serverarray[i]->flags & SERV_USE_RESOLV); i++);
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if (i != nlow)
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nhigh = i;
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else
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{
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/* now look for a server */
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for (i = nlow; i < nhigh && !(daemon->serverarray[i]->flags & SERV_LITERAL_ADDRESS); i++);
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@@ -346,6 +353,7 @@ int filter_servers(int seed, int flags, int *lowout, int *highout)
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}
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}
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}
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}
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*lowout = nlow;
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*highout = nhigh;
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@@ -521,10 +529,10 @@ static int order_qsort(const void *a, const void *b)
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/* Sort all literal NODATA and local IPV4 or IPV6 responses together,
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in a very specific order. We flip the SERV_LITERAL_ADDRESS bit
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so the order is IPv6 literal, IPv4 literal, all-zero literal,
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upstream server, NXDOMAIN literal. */
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unqualified servers, upstream server, NXDOMAIN literal. */
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if (rc == 0)
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rc = ((s2->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS) -
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((s1->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS);
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rc = ((s2->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_USE_RESOLV | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS) -
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((s1->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_USE_RESOLV | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS);
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/* Finally, order by appearance in /etc/resolv.conf etc, for --strict-order */
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if (rc == 0)
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@@ -634,7 +642,7 @@ int add_update_server(int flags,
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{
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size_t size;
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if (flags & SERV_LITERAL_ADDRESS)
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if (flags & SERV_IS_LOCAL)
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{
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if (flags & SERV_6ADDR)
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size = sizeof(struct serv_addr6);
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@@ -656,10 +664,19 @@ int add_update_server(int flags,
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{
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serv->next = daemon->local_domains;
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daemon->local_domains = serv;
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if (flags & SERV_4ADDR)
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((struct serv_addr4*)serv)->addr = local_addr->addr4;
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if (flags & SERV_6ADDR)
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((struct serv_addr6*)serv)->addr = local_addr->addr6;
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}
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else
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{
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struct server *s;
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memset(serv, 0, sizeof(struct server));
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/* Add to the end of the chain, for order */
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if (!daemon->servers)
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daemon->servers = serv;
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@@ -669,25 +686,6 @@ int add_update_server(int flags,
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s->next = serv;
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}
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serv->next = NULL;
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}
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}
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if (!(flags & SERV_IS_LOCAL))
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memset(serv, 0, sizeof(struct server));
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serv->flags = flags;
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serv->domain = alloc_domain;
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serv->domain_len = strlen(alloc_domain);
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if (flags & SERV_4ADDR)
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((struct serv_addr4*)serv)->addr = local_addr->addr4;
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if (flags & SERV_6ADDR)
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((struct serv_addr6*)serv)->addr = local_addr->addr6;
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if (!(flags & SERV_IS_LOCAL))
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{
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#ifdef HAVE_LOOP
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serv->uid = rand32();
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#endif
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@@ -699,6 +697,11 @@ int add_update_server(int flags,
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if (source_addr)
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serv->source_addr = *source_addr;
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}
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}
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serv->flags = flags;
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serv->domain = alloc_domain;
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serv->domain_len = strlen(alloc_domain);
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return 1;
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}
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