On Wed, May 11, 2022 at 09:24:24PM +0900, Ritaro Takenaka wrote:
> Fixes sporadic IPv6 packet loss when flow offloading is enabled.
>
> IPv6 route GC and flowtable GC are not synchronized.
> When dst_cache becomes stale and a packet passes through the flow before
> the flowtable GC teardowns it, the packet can be dropped.
>
> So, it is necessary to check dst every time in packet path.
>
> Signed-off-by: Ritaro Takenaka <ritarot634@xxxxxxxxx>
> ---
> net/netfilter/nf_flow_table_core.c | 23 +----------------------
> net/netfilter/nf_flow_table_ip.c | 17 +++++++++++++++++
> 2 files changed, 18 insertions(+), 22 deletions(-)
>
> diff --git a/net/netfilter/nf_flow_table_core.c b/net/netfilter/nf_flow_table_core.c
> index 3db256da919b..1d99afaf22c1 100644
> --- a/net/netfilter/nf_flow_table_core.c
> +++ b/net/netfilter/nf_flow_table_core.c
> @@ -438,32 +438,11 @@ nf_flow_table_iterate(struct nf_flowtable *flow_table,
> return err;
> }
>
> -static bool flow_offload_stale_dst(struct flow_offload_tuple *tuple)
> -{
> - struct dst_entry *dst;
> -
> - if (tuple->xmit_type == FLOW_OFFLOAD_XMIT_NEIGH ||
> - tuple->xmit_type == FLOW_OFFLOAD_XMIT_XFRM) {
> - dst = tuple->dst_cache;
> - if (!dst_check(dst, tuple->dst_cookie))
> - return true;
> - }
> -
> - return false;
> -}
> -
> -static bool nf_flow_has_stale_dst(struct flow_offload *flow)
> -{
> - return flow_offload_stale_dst(&flow->tuplehash[FLOW_OFFLOAD_DIR_ORIGINAL].tuple) ||
> - flow_offload_stale_dst(&flow->tuplehash[FLOW_OFFLOAD_DIR_REPLY].tuple);
> -}
> -
> static void nf_flow_offload_gc_step(struct nf_flowtable *flow_table,
> struct flow_offload *flow, void *data)
> {
> if (nf_flow_has_expired(flow) ||
> - nf_ct_is_dying(flow->ct) ||
> - nf_flow_has_stale_dst(flow))
> + nf_ct_is_dying(flow->ct))
> set_bit(NF_FLOW_TEARDOWN, &flow->flags);
>
> if (test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {
> diff --git a/net/netfilter/nf_flow_table_ip.c b/net/netfilter/nf_flow_table_ip.c
> index 32c0eb1b4821..402742dd054c 100644
> --- a/net/netfilter/nf_flow_table_ip.c
> +++ b/net/netfilter/nf_flow_table_ip.c
> @@ -367,6 +367,14 @@ nf_flow_offload_ip_hook(void *priv, struct sk_buff *skb,
> if (nf_flow_state_check(flow, iph->protocol, skb, thoff))
> return NF_ACCEPT;
>
> + if (tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_NEIGH ||
> + tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM) {
Probably restore:
static inline bool nf_flow_dst_check(...)
{
if (tuplehash->tuple.xmit_type != FLOW_OFFLOAD_XMIT_NEIGH &&
tuplehash->tuple.xmit_type != FLOW_OFFLOAD_XMIT_XFRM)
return true;
return dst_check(...);
}
and use it.
BTW, could you also search for the Fixes: tag?
Thanks.
> + if (!dst_check(tuplehash->tuple.dst_cache, 0)) {
> + flow_offload_teardown(flow);
> + return NF_ACCEPT;
> + }
> + }
> +
> if (skb_try_make_writable(skb, thoff + hdrsize))
> return NF_DROP;
>
> @@ -624,6 +632,15 @@ nf_flow_offload_ipv6_hook(void *priv, struct sk_buff *skb,
> if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff))
> return NF_ACCEPT;
>
> + if (tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_NEIGH ||
> + tuplehash->tuple.xmit_type == FLOW_OFFLOAD_XMIT_XFRM) {
> + if (!dst_check(tuplehash->tuple.dst_cache,
> + tuplehash->tuple.dst_cookie)) {
> + flow_offload_teardown(flow);
> + return NF_ACCEPT;
> + }
> + }
> +
> if (skb_try_make_writable(skb, thoff + hdrsize))
> return NF_DROP;
>
> --
> 2.34.1
>
