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Commit e16e888b authored by Markus Stenberg's avatar Markus Stenberg Committed by David S. Miller
Browse files

ipv6: Fixed source specific default route handling. 



If there are only IPv6 source specific default routes present, the
host gets -ENETUNREACH on e.g. connect() because ip6_dst_lookup_tail
calls ip6_route_output first, and given source address any, it fails,
and ip6_route_get_saddr is never called.

The change is to use the ip6_route_get_saddr, even if the initial
ip6_route_output fails, and then doing ip6_route_output _again_ after
we have appropriate source address available.

Note that this is '99% fix' to the problem; a correct fix would be to
do route lookups only within addrconf.c when picking a source address,
and never call ip6_route_output before source address has been
populated.

Signed-off-by: default avatarMarkus Stenberg <markus.stenberg@iki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0a801445

net/ipv6/ip6_output.c

+31 −8
Original line number Diff line number Diff line
@@ -886,21 +886,44 @@ static int ip6_dst_lookup_tail(struct sock *sk, 
#endif

	int err;



	if (!*dst)

		*dst = ip6_route_output(net, sk, fl6);



	err = (*dst)->error;

	if (err)

		goto out_err_release;

	/* The correct way to handle this would be to do

	 * ip6_route_get_saddr, and then ip6_route_output; however,

	 * the route-specific preferred source forces the

	 * ip6_route_output call _before_ ip6_route_get_saddr.

	 *

	 * In source specific routing (no src=any default route),

	 * ip6_route_output will fail given src=any saddr, though, so

	 * that's why we try it again later.

	 */

	if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {

		struct rt6_info *rt;

		bool had_dst = *dst != NULL;



	if (ipv6_addr_any(&fl6->saddr)) {

		struct rt6_info *rt = (struct rt6_info *) *dst;

		if (!had_dst)

			*dst = ip6_route_output(net, sk, fl6);

		rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;

		err = ip6_route_get_saddr(net, rt, &fl6->daddr,

					  sk ? inet6_sk(sk)->srcprefs : 0,

					  &fl6->saddr);

		if (err)

			goto out_err_release;



		/* If we had an erroneous initial result, pretend it

		 * never existed and let the SA-enabled version take

		 * over.

		 */

		if (!had_dst && (*dst)->error) {

			dst_release(*dst);

			*dst = NULL;

		}

	}



	if (!*dst)

		*dst = ip6_route_output(net, sk, fl6);



	err = (*dst)->error;

	if (err)

		goto out_err_release;



#ifdef CONFIG_IPV6_OPTIMISTIC_DAD

	/*

net/ipv6/route.c

+3 −2
Original line number Diff line number Diff line
@@ -2245,9 +2245,10 @@ int ip6_route_get_saddr(struct net *net, 
			unsigned int prefs,

			struct in6_addr *saddr)

{

	struct inet6_dev *idev = ip6_dst_idev((struct dst_entry *)rt);

	struct inet6_dev *idev =

		rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;

	int err = 0;

	if (rt->rt6i_prefsrc.plen)

	if (rt && rt->rt6i_prefsrc.plen)

		*saddr = rt->rt6i_prefsrc.addr;

	else

		err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,