target/linux/generic/patches-4.0/667-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 @@ -886,22 +886,45 @@ static int ip6_dst_lookup_tail(struct sock *sk,
  32  #endif
  33         int err;
  34
  35 -       if (!*dst)
  36 -               *dst = ip6_route_output(net, sk, fl6);
  37 -
  38 -       err = (*dst)->error;
  39 -       if (err)
  40 -               goto out_err_release;
  41 +       /* The correct way to handle this would be to do
  42 +        * ip6_route_get_saddr, and then ip6_route_output; however,
  43 +        * the route-specific preferred source forces the
  44 +        * ip6_route_output call _before_ ip6_route_get_saddr.
  45 +        *
  46 +        * In source specific routing (no src=any default route),
  47 +        * ip6_route_output will fail given src=any saddr, though, so
  48 +        * that's why we try it again later.
  49 +        */
  50 +       if (ipv6_addr_any(&fl6->saddr) && (!*dst || !(*dst)->error)) {
  51 +               struct rt6_info *rt;
  52 +               bool had_dst = *dst != NULL;
  53
  54 -       if (ipv6_addr_any(&fl6->saddr)) {
  55 -               struct rt6_info *rt = (struct rt6_info *) *dst;
  56 +               if (!had_dst)
  57 +                       *dst = ip6_route_output(net, sk, fl6);
  58 +               rt = (*dst)->error ? NULL : (struct rt6_info *)*dst;
  59                 err = ip6_route_get_saddr(net, rt, &fl6->daddr,
  60                                           sk ? inet6_sk(sk)->srcprefs : 0,
  61                                           &fl6->saddr);
  62                 if (err)
  63                         goto out_err_release;
  64 +
  65 +               /* If we had an erroneous initial result, pretend it
  66 +                * never existed and let the SA-enabled version take
  67 +                * over.
  68 +                */
  69 +               if (!had_dst && (*dst)->error) {
  70 +                       dst_release(*dst);
  71 +                       *dst = NULL;
  72 +               }
  73         }
  74
  75 +       if (!*dst)
  76 +               *dst = ip6_route_output(net, sk, fl6);
  77 +
  78 +       err = (*dst)->error;
  79 +       if (err)
  80 +               goto out_err_release;
  81 +
  82  #ifdef CONFIG_IPV6_OPTIMISTIC_DAD
  83         /*
  84          * Here if the dst entry we've looked up
  85 diff --git a/net/ipv6/route.c b/net/ipv6/route.c
  86 index 5c48293..d358888 100644
  87 --- a/net/ipv6/route.c
  88 +++ b/net/ipv6/route.c
  89 @@ -2245,9 +2245,10 @@ int ip6_route_get_saddr(struct net *net,
  90                         unsigned int prefs,
  91                         struct in6_addr *saddr)
  92  {
  93 -       struct inet6_dev *idev = ip6_dst_idev((struct dst_entry *)rt);
  94 +       struct inet6_dev *idev =
  95 +               rt ? ip6_dst_idev((struct dst_entry *)rt) : NULL;
  96         int err = 0;
  97 -       if (rt->rt6i_prefsrc.plen)
  98 +       if (rt && rt->rt6i_prefsrc.plen)
  99                 *saddr = rt->rt6i_prefsrc.addr;
 100         else
 101                 err = ipv6_dev_get_saddr(net, idev ? idev->dev : NULL,
 102 --
 103 2.1.4
 104