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netfilter: flowtable: move dst_check to packet path

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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: 227e1e4d0d ("netfilter: nf_flowtable: skip device lookup from interface index")
Signed-off-by: Ritaro Takenaka <ritarot634@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Ritaro Takenaka 2022-05-17 12:55:30 +02:00 committed by Pablo Neira Ayuso
parent e5eaac2beb
commit 2738d9d963
2 changed files with 20 additions and 22 deletions
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23
net/netfilter/nf_flow_table_core.c
View File

@ -421,32 +421,11 @@ 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))
flow_offload_teardown(flow);
if (test_bit(NF_FLOW_TEARDOWN, &flow->flags)) {

19
net/netfilter/nf_flow_table_ip.c
View File

@ -248,6 +248,15 @@ static bool nf_flow_exceeds_mtu(const struct sk_buff *skb, unsigned int mtu)
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)
@ -367,6 +376,11 @@ 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 (!nf_flow_dst_check(&tuplehash->tuple)) {
flow_offload_teardown(flow);
return NF_ACCEPT;
}
if (skb_try_make_writable(skb, thoff + hdrsize))
return NF_DROP;
@ -624,6 +638,11 @@ 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 (!nf_flow_dst_check(&tuplehash->tuple)) {
flow_offload_teardown(flow);
return NF_ACCEPT;
}
if (skb_try_make_writable(skb, thoff + hdrsize))
return NF_DROP;