From 2738d9d963bd1f06d5114c2b4fa5771a95703991 Mon Sep 17 00:00:00 2001 From: Ritaro Takenaka Date: Tue, 17 May 2022 12:55:30 +0200 Subject: [PATCH] netfilter: flowtable: move dst_check to packet path 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. Fixes: 227e1e4d0d6c ("netfilter: nf_flowtable: skip device lookup from interface index") Signed-off-by: Ritaro Takenaka Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_flow_table_core.c | 23 +---------------------- net/netfilter/nf_flow_table_ip.c | 19 +++++++++++++++++++ 2 files changed, 20 insertions(+), 22 deletions(-) --- a/net/netfilter/nf_flow_table_core.c +++ b/net/netfilter/nf_flow_table_core.c @@ -433,33 +433,12 @@ nf_flow_table_iterate(struct nf_flowtabl 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 flow_offload *flow, void *data) { struct nf_flowtable *flow_table = 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)) { --- a/net/netfilter/nf_flow_table_ip.c +++ b/net/netfilter/nf_flow_table_ip.c @@ -229,6 +229,15 @@ static bool nf_flow_exceeds_mtu(const st return true; } +static inline bool nf_flow_dst_check(struct flow_offload_tuple *tuple) +{ + if (tuple->xmit_type != FLOW_OFFLOAD_XMIT_NEIGH && + tuple->xmit_type != FLOW_OFFLOAD_XMIT_XFRM) + return true; + + return dst_check(tuple->dst_cache, tuple->dst_cookie); +} + static unsigned int nf_flow_xmit_xfrm(struct sk_buff *skb, const struct nf_hook_state *state, struct dst_entry *dst) @@ -364,6 +373,11 @@ nf_flow_offload_ip_hook(void *priv, stru if (nf_flow_state_check(flow, iph->protocol, skb, thoff)) return NF_ACCEPT; + if (!nf_flow_dst_check(&tuplehash->tuple)) { + flow_offload_teardown(flow); + return NF_ACCEPT; + } + if (skb_try_make_writable(skb, thoff + hdrsize)) return NF_DROP; @@ -600,6 +614,11 @@ nf_flow_offload_ipv6_hook(void *priv, st if (nf_flow_state_check(flow, ip6h->nexthdr, skb, thoff)) return NF_ACCEPT; + if (!nf_flow_dst_check(&tuplehash->tuple)) { + flow_offload_teardown(flow); + return NF_ACCEPT; + } + if (skb_try_make_writable(skb, thoff + hdrsize)) return NF_DROP;