Re: [PATCH net-next] net: Fix vti use case with oif in dst lookups for IPv6

[David Ahern]

On 10/9/15 1:17 AM, Steffen Klassert wrote:
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 30caa289c5db..5cedfda4b241 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -37,6 +37,7 @@ static struct dst_entry *xfrm6_dst_lookup(struct net *net, 
int tos, int oif,
        memset(&fl6, 0, sizeof(fl6));
        fl6.flowi6_oif = oif;
+       fl6.flowi6_flags = FLOWI_FLAG_SKIP_NH_OIF;
        memcpy(&fl6.daddr, daddr, sizeof(fl6.daddr));
        if (saddr)
                memcpy(&fl6.saddr, saddr, sizeof(fl6.saddr));

I found that this fix is still not sufficient with the mip6
(Mobile IPv6) use case.

It does not even fix the vti case. The behaviour of the vti devices is
the same, with and without the patch.


The attached patch applied to Linus' tree works for me. Currently the 
above change is not in his tree, so I added it to this patch. Once you 
confirm that it works for you I'll create the delta-patch for net and 
send out.

Thanks,
David
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 92b1aa38f121..2dbd73014a1b 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -874,7 +874,8 @@ static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
 #ifdef CONFIG_IPV6_SUBTREES
            ip6_rt_check(&rt->rt6i_src, &fl6->saddr, np->saddr_cache) ||
 #endif
-           (fl6->flowi6_oif && fl6->flowi6_oif != dst->dev->ifindex)) {
+          (!(fl6->flowi6_flags & FLOWI_FLAG_SKIP_NH_OIF) &&
+             (fl6->flowi6_oif && fl6->flowi6_oif != dst->dev->ifindex))) {
                dst_release(dst);
                dst = NULL;
        }
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index cb32ce250db0..df24cff4a0cb 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1068,6 +1068,9 @@ static struct rt6_info *ip6_pol_route(struct net *net, 
struct fib6_table *table,
        fn = fib6_lookup(&table->tb6_root, &fl6->daddr, &fl6->saddr);
        saved_fn = fn;
 
+       if (fl6->flowi6_flags & FLOWI_FLAG_SKIP_NH_OIF)
+               oif = 0;
+
 redo_rt6_select:
        rt = rt6_select(fn, oif, strict);
        if (rt->rt6i_nsiblings)
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 30caa289c5db..5cedfda4b241 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -37,6 +37,7 @@ static struct dst_entry *xfrm6_dst_lookup(struct net *net, 
int tos, int oif,
 
        memset(&fl6, 0, sizeof(fl6));
        fl6.flowi6_oif = oif;
+       fl6.flowi6_flags = FLOWI_FLAG_SKIP_NH_OIF;
        memcpy(&fl6.daddr, daddr, sizeof(fl6.daddr));
        if (saddr)
                memcpy(&fl6.saddr, saddr, sizeof(fl6.saddr));