From 9f13ded8d3c715147c4759f937cfb712c185ca13 Mon Sep 17 00:00:00 2001 From: Jarno Rajahalme Date: Thu, 10 Mar 2016 10:54:18 -0800 Subject: [PATCH] openvswitch: Add commentary to conntrack.c This makes the code easier to understand and the following patches more focused. Signed-off-by: Jarno Rajahalme Acked-by: Joe Stringer Signed-off-by: Pablo Neira Ayuso --- net/openvswitch/conntrack.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c index 304529015744..2c2bf071f6d6 100644 --- a/net/openvswitch/conntrack.c +++ b/net/openvswitch/conntrack.c @@ -152,8 +152,12 @@ static void ovs_ct_update_key(const struct sk_buff *skb, ct = nf_ct_get(skb, &ctinfo); if (ct) { state = ovs_ct_get_state(ctinfo); + /* All unconfirmed entries are NEW connections. */ if (!nf_ct_is_confirmed(ct)) state |= OVS_CS_F_NEW; + /* OVS persists the related flag for the duration of the + * connection. + */ if (ct->master) state |= OVS_CS_F_RELATED; zone = nf_ct_zone(ct); @@ -165,6 +169,9 @@ static void ovs_ct_update_key(const struct sk_buff *skb, __ovs_ct_update_key(key, state, zone, ct); } +/* This is called to initialize CT key fields possibly coming in from the local + * stack. + */ void ovs_ct_fill_key(const struct sk_buff *skb, struct sw_flow_key *key) { ovs_ct_update_key(skb, NULL, key, false); @@ -199,7 +206,6 @@ static int ovs_ct_set_mark(struct sk_buff *skb, struct sw_flow_key *key, struct nf_conn *ct; u32 new_mark; - /* The connection could be invalid, in which case set_mark is no-op. */ ct = nf_ct_get(skb, &ctinfo); if (!ct) @@ -375,6 +381,11 @@ static bool skb_nfct_cached(const struct net *net, const struct sk_buff *skb, return true; } +/* Pass 'skb' through conntrack in 'net', using zone configured in 'info', if + * not done already. Update key with new CT state. + * Note that if the packet is deemed invalid by conntrack, skb->nfct will be + * set to NULL and 0 will be returned. + */ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key, const struct ovs_conntrack_info *info, struct sk_buff *skb) @@ -418,6 +429,13 @@ static int ovs_ct_lookup(struct net *net, struct sw_flow_key *key, { struct nf_conntrack_expect *exp; + /* If we pass an expected packet through nf_conntrack_in() the + * expectation is typically removed, but the packet could still be + * lost in upcall processing. To prevent this from happening we + * perform an explicit expectation lookup. Expected connections are + * always new, and will be passed through conntrack only when they are + * committed, as it is OK to remove the expectation at that time. + */ exp = ovs_ct_expect_find(net, &info->zone, info->family, skb); if (exp) { u8 state; @@ -455,6 +473,7 @@ static int ovs_ct_commit(struct net *net, struct sw_flow_key *key, err = __ovs_ct_lookup(net, key, info, skb); if (err) return err; + /* This is a no-op if the connection has already been confirmed. */ if (nf_conntrack_confirm(skb) != NF_ACCEPT) return -EINVAL; -- 2.39.5