commit 2a79fd3908acd88e6cb0e620c314d7b1fee56a02 upstream.

Some drivers, such as vxlan and wireguard, use the skb's dst in order to determine things like PMTU. They therefore loose functionality when flow offloading is enabled. So, we ensure the skb has it before xmit'ing it in the offloading path.

Signed-off-by: Jason A. Donenfeld Jason@zx2c4.com --- net/ipv4/netfilter/nf_flow_table_ipv4.c | 5 +++-- net/ipv6/netfilter/nf_flow_table_ipv6.c | 1 + 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/netfilter/nf_flow_table_ipv4.c b/net/ipv4/netfilter/nf_flow_table_ipv4.c index 0cd46bffa469..fc3923932eda 100644 --- a/net/ipv4/netfilter/nf_flow_table_ipv4.c +++ b/net/ipv4/netfilter/nf_flow_table_ipv4.c @@ -213,7 +213,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, enum flow_offload_tuple_dir dir; struct flow_offload *flow; struct net_device *outdev; - const struct rtable *rt; + struct rtable *rt; struct iphdr *iph; __be32 nexthop;

@@ -234,7 +234,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb, dir = tuplehash->tuple.dir; flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);

- rt = (const struct rtable *)flow->tuplehash[dir].tuple.dst_cache; + rt = (struct rtable *)flow->tuplehash[dir].tuple.dst_cache; if (unlikely(nf_flow_exceeds_mtu(skb, rt))) return NF_ACCEPT;

@@ -251,6 +251,7 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,

skb->dev = outdev; nexthop = rt_nexthop(rt, flow->tuplehash[!dir].tuple.src_v4.s_addr); + skb_dst_set_noref(skb, &rt->dst); neigh_xmit(NEIGH_ARP_TABLE, outdev, &nexthop, skb);

return NF_STOLEN; diff --git a/net/ipv6/netfilter/nf_flow_table_ipv6.c b/net/ipv6/netfilter/nf_flow_table_ipv6.c index 207cb35569b1..2d6652146bba 100644 --- a/net/ipv6/netfilter/nf_flow_table_ipv6.c +++ b/net/ipv6/netfilter/nf_flow_table_ipv6.c @@ -243,6 +243,7 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,

skb->dev = outdev; nexthop = rt6_nexthop(rt, &flow->tuplehash[!dir].tuple.src_v6); + skb_dst_set_noref(skb, &rt->dst); neigh_xmit(NEIGH_ND_TABLE, outdev, nexthop, skb);

return NF_STOLEN;