target/linux/generic/patches-3.18/667-ipv6-Fixed-source-specific-default-route-handling.patch

   1 From e16e888b525503be05b3aea64190e8b3bdef44d0 Mon Sep 17 00:00:00 2001
   2 From: Markus Stenberg <markus.stenberg@iki.fi>
   3 Date: Tue, 5 May 2015 13:36:59 +0300
   4 Subject: [PATCH] ipv6: Fixed source specific default route handling.
   5
   6 If there are only IPv6 source specific default routes present, the
   7 host gets -ENETUNREACH on e.g. connect() because ip6_dst_lookup_tail
   8 calls ip6_route_output first, and given source address any, it fails,
   9 and ip6_route_get_saddr is never called.
  10
  11 The change is to use the ip6_route_get_saddr, even if the initial
  12 ip6_route_output fails, and then doing ip6_route_output _again_ after
  13 we have appropriate source address available.
  14
  15 Note that this is '99% fix' to the problem; a correct fix would be to
  16 do route lookups only within addrconf.c when picking a source address,
  17 and never call ip6_route_output before source address has been
  18 populated.
  19
  20 Signed-off-by: Markus Stenberg <markus.stenberg@iki.fi>
  21 Signed-off-by: David S. Miller <davem@davemloft.net>
  22 ---
  23  net/ipv6/ip6_output.c | 39 +++++++++++++++++++++++++++++++--------
  24  net/ipv6/route.c      |  5 +++--
  25  2 files changed, 34 insertions(+), 10 deletions(-)
  26
  27 --- a/net/ipv6/ip6_output.c
  28 +++ b/net/ipv6/ip6_output.c
  29 @@ -900,21 +900,45 @@ static int ip6_dst_lookup_tail(struct so
  30  #endif
  31         int err;
  32
  33 -       if (*dst == NULL)
  34 -               *dst = ip6_route_output(net, sk, fl6);
  35 -
  36 -       if ((err = (*dst)->error))
  37 -               goto out_err_release;
  38 +       /* The correct way to handle this would be to do
  39 +        * ip6_route_get_saddr, and then ip6_route_output; however,
  40 +        * the route-specific preferred source forces the
  41 +        * ip6_route_output call _before_ ip6_route_get_saddr.
  42 +        *
  43 +        * In source specific routing (no src=any default route),
  44 +        * ip6_route_output will fail given src=any saddr, though, so
  45 +        * that's why we try it again later.
  46 +        */
  47 +       if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
  48 +               struct rt6_info *rt;
  49 +               bool had_dst = *dst != NULL;
  50
  51 -       if (ipv6_addr_any(&fl6->saddr)) {
  52 -               struct rt6_info *rt = (struct rt6_info *) *dst;
  53 +               if (!had_dst)
  54 +                       *dst = ip6_route_output(net, sk, fl6);
  55 +               rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
  56                 err = ip6_route_get_saddr(net, rt, &fl6->daddr,
  57                                           sk ? inet6_sk(sk)->srcprefs : 0,
  58                                           &fl6->saddr);
  59                 if (err)
  60                         goto out_err_release;
  61 +
  62 +               /* If we had an erroneous initial result, pretend it
  63 +                * never existed and let the SA-enabled version take
  64 +                * over.
  65 +                */
  66 +               if (!had_dst && (*dst)->error) {
  67 +                       dst_release(*dst);
  68 +                       *dst = NULL;
  69 +               }
  70         }
  71
  72 +       if (!*dst)
  73 +               *dst = ip6_route_output(net, sk, fl6);
  74 +
  75 +       err = (*dst)->error;
  76 +       if (err)
  77 +               goto out_err_release;
  78 +
  79  #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
  80         /*
  81          * Here if the dst entry we've looked up
  82 --- a/net/ipv6/route.c
  83 +++ b/net/ipv6/route.c
  84 @@ -2182,9 +2182,10 @@ int ip6_route_get_saddr(struct net *net,
  85                         unsigned int prefs,
  86                         struct in6_addr *saddr)
  87  {
  88 -       struct inet6_dev *idev = ip6_dst_idev((struct dst_entry *)rt);
  89 +       struct inet6_dev *idev =
  90 +               rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;
  91         int err = 0;
  92 -       if (rt->rt6i_prefsrc.plen)
  93 +       if (rt && rt->rt6i_prefsrc.plen)
  94                 *saddr = rt->rt6i_prefsrc.addr;
  95         else
  96                 err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,