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Fix confusion is server=/domain/# combined with server|address=/domain/....

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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
2021-09-18 23:01:12 +01:00
parent 4ac517e4ac
commit de372d6914
2 changed files with 75 additions and 72 deletions
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24
src/dnsmasq.h
View File

@@ -530,18 +530,18 @@ union mysockaddr {
/* The actual values here matter, since we sort on them to get records in the order /* The actual values here matter, since we sort on them to get records in the order
IPv6 addr, IPv4 addr, all zero return, no-data return, send upstream. */ IPv6 addr, IPv4 addr, all zero return, resolvconf servers, upstream server, no-data return */
#define SERV_LITERAL_ADDRESS 1 /* addr is the answer, or NoDATA is the answer, depending on the next three flags */ #define SERV_LITERAL_ADDRESS 1 /* addr is the answer, or NoDATA is the answer, depending on the next four flags */
#define SERV_ALL_ZEROS 2 /* return all zeros for A and AAAA */ #define SERV_USE_RESOLV 2 /* forward this domain in the normal way */
#define SERV_4ADDR 4 /* addr is IPv4 */ #define SERV_ALL_ZEROS 4 /* return all zeros for A and AAAA */
#define SERV_6ADDR 8 /* addr is IPv6 */ #define SERV_4ADDR 8 /* addr is IPv4 */
#define SERV_HAS_SOURCE 16 /* source address defined */ #define SERV_6ADDR 16 /* addr is IPv6 */
#define SERV_FOR_NODOTS 32 /* server for names with no domain part only */ #define SERV_HAS_SOURCE 32 /* source address defined */
#define SERV_WARNED_RECURSIVE 64 /* avoid warning spam */ #define SERV_FOR_NODOTS 64 /* server for names with no domain part only */
#define SERV_FROM_DBUS 128 /* 1 if source is DBus */ #define SERV_WARNED_RECURSIVE 128 /* avoid warning spam */
#define SERV_MARK 256 /* for mark-and-delete and log code */ #define SERV_FROM_DBUS 256 /* 1 if source is DBus */
#define SERV_WILDCARD 512 /* domain has leading '*' */ #define SERV_MARK 512 /* for mark-and-delete and log code */
#define SERV_USE_RESOLV 1024 /* forward this domain in the normal way */ #define SERV_WILDCARD 1024 /* domain has leading '*' */
#define SERV_FROM_RESOLV 2048 /* 1 for servers from resolv, 0 for command line. */ #define SERV_FROM_RESOLV 2048 /* 1 for servers from resolv, 0 for command line. */
#define SERV_FROM_FILE 4096 /* read from --servers-file */ #define SERV_FROM_FILE 4096 /* read from --servers-file */
#define SERV_LOOP 8192 /* server causes forwarding loop */ #define SERV_LOOP 8192 /* server causes forwarding loop */

65
src/domain-match.c
View File

@@ -207,16 +207,16 @@ int lookup_domain(char *domain, int flags, int *lowout, int *highout)
} }
} }
if (found) if (found && filter_servers(try, flags, &nlow, &nhigh))
{
/* We've matched a setting which says to use servers without a domain.
Continue the search with empty query */
if (daemon->serverarray[try]->flags & SERV_USE_RESOLV)
crop_query = qlen;
else if (filter_servers(try, flags, &nlow, &nhigh))
/* We have a match, but it may only be (say) an IPv6 address, and /* We have a match, but it may only be (say) an IPv6 address, and
if the query wasn't for an AAAA record, it's no good, and we need if the query wasn't for an AAAA record, it's no good, and we need
to continue generalising */ to continue generalising */
{
/* We've matched a setting which says to use servers without a domain.
Continue the search with empty query */
if (daemon->serverarray[nlow]->flags & SERV_USE_RESOLV)
crop_query = qlen;
else
break; break;
} }
} }
@@ -293,7 +293,7 @@ int filter_servers(int seed, int flags, int *lowout, int *highout)
else else
{ {
/* Now the servers are on order between low and high, in the order /* Now the servers are on order between low and high, in the order
IPv6 addr, IPv4 addr, return zero for both, send upstream, no-data return. IPv6 addr, IPv4 addr, return zero for both, resolvconf servers, send upstream, no-data return.
See which of those match our query in that priority order and narrow (low, high) */ See which of those match our query in that priority order and narrow (low, high) */
@@ -321,6 +321,13 @@ int filter_servers(int seed, int flags, int *lowout, int *highout)
{ {
nlow = i; nlow = i;
/* Short to resolv.conf servers */
for (i = nlow; i < nhigh && (daemon->serverarray[i]->flags & SERV_USE_RESOLV); i++);
if (i != nlow)
nhigh = i;
else
{
/* now look for a server */ /* now look for a server */
for (i = nlow; i < nhigh && !(daemon->serverarray[i]->flags & SERV_LITERAL_ADDRESS); i++); for (i = nlow; i < nhigh && !(daemon->serverarray[i]->flags & SERV_LITERAL_ADDRESS); i++);
@@ -346,6 +353,7 @@ int filter_servers(int seed, int flags, int *lowout, int *highout)
} }
} }
} }
}
*lowout = nlow; *lowout = nlow;
*highout = nhigh; *highout = nhigh;
@@ -521,10 +529,10 @@ static int order_qsort(const void *a, const void *b)
/* Sort all literal NODATA and local IPV4 or IPV6 responses together, /* Sort all literal NODATA and local IPV4 or IPV6 responses together,
in a very specific order. We flip the SERV_LITERAL_ADDRESS bit in a very specific order. We flip the SERV_LITERAL_ADDRESS bit
so the order is IPv6 literal, IPv4 literal, all-zero literal, so the order is IPv6 literal, IPv4 literal, all-zero literal,
upstream server, NXDOMAIN literal. */ unqualified servers, upstream server, NXDOMAIN literal. */
if (rc == 0) if (rc == 0)
rc = ((s2->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS) - rc = ((s2->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_USE_RESOLV | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS) -
((s1->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS); ((s1->flags & (SERV_LITERAL_ADDRESS | SERV_4ADDR | SERV_6ADDR | SERV_USE_RESOLV | SERV_ALL_ZEROS)) ^ SERV_LITERAL_ADDRESS);
/* Finally, order by appearance in /etc/resolv.conf etc, for --strict-order */ /* Finally, order by appearance in /etc/resolv.conf etc, for --strict-order */
if (rc == 0) if (rc == 0)
@@ -634,7 +642,7 @@ int add_update_server(int flags,
{ {
size_t size; size_t size;
if (flags & SERV_LITERAL_ADDRESS) if (flags & SERV_IS_LOCAL)
{ {
if (flags & SERV_6ADDR) if (flags & SERV_6ADDR)
size = sizeof(struct serv_addr6); size = sizeof(struct serv_addr6);
@@ -656,10 +664,19 @@ int add_update_server(int flags,
{ {
serv->next = daemon->local_domains; serv->next = daemon->local_domains;
daemon->local_domains = serv; daemon->local_domains = serv;
if (flags & SERV_4ADDR)
((struct serv_addr4*)serv)->addr = local_addr->addr4;
if (flags & SERV_6ADDR)
((struct serv_addr6*)serv)->addr = local_addr->addr6;
} }
else else
{ {
struct server *s; struct server *s;
memset(serv, 0, sizeof(struct server));
/* Add to the end of the chain, for order */ /* Add to the end of the chain, for order */
if (!daemon->servers) if (!daemon->servers)
daemon->servers = serv; daemon->servers = serv;
@@ -669,25 +686,6 @@ int add_update_server(int flags,
s->next = serv; s->next = serv;
} }
serv->next = NULL;
}
}
if (!(flags & SERV_IS_LOCAL))
memset(serv, 0, sizeof(struct server));
serv->flags = flags;
serv->domain = alloc_domain;
serv->domain_len = strlen(alloc_domain);
if (flags & SERV_4ADDR)
((struct serv_addr4*)serv)->addr = local_addr->addr4;
if (flags & SERV_6ADDR)
((struct serv_addr6*)serv)->addr = local_addr->addr6;
if (!(flags & SERV_IS_LOCAL))
{
#ifdef HAVE_LOOP #ifdef HAVE_LOOP
serv->uid = rand32(); serv->uid = rand32();
#endif #endif
@@ -699,6 +697,11 @@ int add_update_server(int flags,
if (source_addr) if (source_addr)
serv->source_addr = *source_addr; serv->source_addr = *source_addr;
} }
}
serv->flags = flags;
serv->domain = alloc_domain;
serv->domain_len = strlen(alloc_domain);
return 1; return 1;
} }