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 diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
  28 index 7fde1f2..c217775 100644
  29 --- a/net/ipv6/ip6_output.c
  30 +++ b/net/ipv6/ip6_output.c
  31 @@ -897,21 +897,45 @@ static int ip6_dst_lookup_tail(struct so
  32  #endif
  33         int err;
  34
  35 -       if (*dst == NULL)
  36 -               *dst = ip6_route_output(net, sk, fl6);
  37 -
  38 -       if ((err = (*dst)->error))
  39 -               goto out_err_release;
  40 +       /* The correct way to handle this would be to do
  41 +        * ip6_route_get_saddr, and then ip6_route_output; however,
  42 +        * the route-specific preferred source forces the
  43 +        * ip6_route_output call _before_ ip6_route_get_saddr.
  44 +        *
  45 +        * In source specific routing (no src=any default route),
  46 +        * ip6_route_output will fail given src=any saddr, though, so
  47 +        * that's why we try it again later.
  48 +        */
  49 +       if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
  50 +               struct rt6_info *rt;
  51 +               bool had_dst = *dst != NULL;
  52
  53 -       if (ipv6_addr_any(&fl6->saddr)) {
  54 -               struct rt6_info *rt = (struct rt6_info *) *dst;
  55 +               if (!had_dst)
  56 +                       *dst = ip6_route_output(net, sk, fl6);
  57 +               rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
  58                 err = ip6_route_get_saddr(net, rt, &fl6->daddr,
  59                                           sk ? inet6_sk(sk)->srcprefs : 0,
  60                                           &fl6->saddr);
  61                 if (err)
  62                         goto out_err_release;
  63 +
  64 +               /* If we had an erroneous initial result, pretend it
  65 +                * never existed and let the SA-enabled version take
  66 +                * over.
  67 +                */
  68 +               if (!had_dst && (*dst)->error) {
  69 +                       dst_release(*dst);
  70 +                       *dst = NULL;
  71 +               }
  72         }
  73
  74 +       if (!*dst)
  75 +               *dst = ip6_route_output(net, sk, fl6);
  76 +
  77 +       err = (*dst)->error;
  78 +       if (err)
  79 +               goto out_err_release;
  80 +
  81  #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
  82         /*
  83          * Here if the dst entry we've looked up
  84 --- a/net/ipv6/route.c
  85 +++ b/net/ipv6/route.c
  86 @@ -2215,9 +2215,10 @@ int ip6_route_get_saddr(struct net *net,
  87                         unsigned int prefs,
  88                         struct in6_addr *saddr)
  89  {
  90 -       struct inet6_dev *idev = ip6_dst_idev((struct dst_entry *)rt);
  91 +       struct inet6_dev *idev =
  92 +               rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;
  93         int err = 0;
  94 -       if (rt->rt6i_prefsrc.plen)
  95 +       if (rt && rt->rt6i_prefsrc.plen)
  96                 *saddr = rt->rt6i_prefsrc.addr;
  97         else
  98                 err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,