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Date: Tue, 3 Mar 2020 16:30:53 +0200
From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To: Paul Blakey <paulb@...lanox.com>,
Saeed Mahameed <saeedm@...lanox.com>,
Oz Shlomo <ozsh@...lanox.com>,
Jakub Kicinski <jakub.kicinski@...ronome.com>,
Vlad Buslov <vladbu@...lanox.com>,
David Miller <davem@...emloft.net>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Jiri Pirko <jiri@...lanox.com>, Roi Dayan <roid@...lanox.com>
Subject: Re: [PATCH net-next v5 3/3] net/sched: act_ct: Software offload of
established flows
On 03/03/2020 16:21, Paul Blakey wrote:
> Offload nf conntrack processing by looking up the 5-tuple in the
> zone's flow table.
>
> The nf conntrack module will process the packets until a connection is
> in established state. Once in established state, the ct state pointer
> (nf_conn) will be restored on the skb from a successful ft lookup.
>
> Signed-off-by: Paul Blakey <paulb@...lanox.com>
> Acked-by: Jiri Pirko <jiri@...lanox.com>
> ---
> Changelog:
> v4->v5:
> Re-read ip/ip6 header after pulling as skb ptrs may change
> Use pskb_network_may_pull instaed of pskb_may_pull
> v1->v2:
> Add !skip_add curly braces
> Removed extra setting thoff again
> Check tcp proto outside of tcf_ct_flow_table_check_tcp
>
> net/sched/act_ct.c | 162 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 160 insertions(+), 2 deletions(-)
>
Hi Paul,
Thanks for making the changes, I have two more questions below, missed these changes
on my previous review, sorry about that.
> diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
> index 2ab38431..5aff5e7 100644
> --- a/net/sched/act_ct.c
> +++ b/net/sched/act_ct.c
> @@ -186,6 +186,157 @@ static void tcf_ct_flow_table_process_conn(struct tcf_ct_flow_table *ct_ft,
> tcf_ct_flow_table_add(ct_ft, ct, tcp);
> }
>
> +static bool
> +tcf_ct_flow_table_fill_tuple_ipv4(struct sk_buff *skb,
> + struct flow_offload_tuple *tuple)
> +{
> + struct flow_ports *ports;
> + unsigned int thoff;
> + struct iphdr *iph;
> +
> + if (!pskb_network_may_pull(skb, sizeof(*iph)))
> + return false;
> +
> + iph = ip_hdr(skb);
> + thoff = iph->ihl * 4;
> +
> + if (ip_is_fragment(iph) ||
> + unlikely(thoff != sizeof(struct iphdr)))
> + return false;
> +
> + if (iph->protocol != IPPROTO_TCP &&
> + iph->protocol != IPPROTO_UDP)
> + return false;
> +
> + if (iph->ttl <= 1)
> + return false;
> +
> + if (!pskb_network_may_pull(skb, thoff + sizeof(*ports)))
> + return false;
> +
> + iph = ip_hdr(skb);
> + ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
> +
> + tuple->src_v4.s_addr = iph->saddr;
> + tuple->dst_v4.s_addr = iph->daddr;
> + tuple->src_port = ports->source;
> + tuple->dst_port = ports->dest;
> + tuple->l3proto = AF_INET;
> + tuple->l4proto = iph->protocol;
> +
> + return true;
> +}
> +
> +static bool
> +tcf_ct_flow_table_fill_tuple_ipv6(struct sk_buff *skb,
> + struct flow_offload_tuple *tuple)
> +{
> + struct flow_ports *ports;
> + struct ipv6hdr *ip6h;
> + unsigned int thoff;
> +
> + if (!pskb_network_may_pull(skb, sizeof(*ip6h)))
> + return false;
> +
> + ip6h = ipv6_hdr(skb);
> +
> + if (ip6h->nexthdr != IPPROTO_TCP &&
> + ip6h->nexthdr != IPPROTO_UDP)
> + return false;
> +
> + if (ip6h->hop_limit <= 1)
> + return false;
> +
> + thoff = sizeof(*ip6h);
> + if (!pskb_network_may_pull(skb, thoff + sizeof(*ports)))
> + return false;
> +
> + ip6h = ipv6_hdr(skb);
> + ports = (struct flow_ports *)(skb_network_header(skb) + thoff);
> +
> + tuple->src_v6 = ip6h->saddr;
> + tuple->dst_v6 = ip6h->daddr;
> + tuple->src_port = ports->source;
> + tuple->dst_port = ports->dest;
> + tuple->l3proto = AF_INET6;
> + tuple->l4proto = ip6h->nexthdr;
> +
> + return true;
> +}
> +
> +static bool tcf_ct_flow_table_check_tcp(struct flow_offload *flow,
> + struct sk_buff *skb,
> + unsigned int thoff)
> +{
> + struct tcphdr *tcph;
> +
> + if (!pskb_may_pull(skb, thoff + sizeof(*tcph)))
Sorry, I missed this spot in my previous review, but shouldn't this follow the
same logic for the pull ?
> + return false;
> +
> + tcph = (void *)(skb_network_header(skb) + thoff);
> + if (unlikely(tcph->fin || tcph->rst)) {
> + flow_offload_teardown(flow);
> + return false;
> + }
> +
> + return true;
> +}
> +
> +static bool tcf_ct_flow_table_lookup(struct tcf_ct_params *p,
> + struct sk_buff *skb,
> + u8 family)
> +{
> + struct nf_flowtable *nf_ft = &p->ct_ft->nf_ft;
> + struct flow_offload_tuple_rhash *tuplehash;
> + struct flow_offload_tuple tuple = {};
> + enum ip_conntrack_info ctinfo;
> + struct flow_offload *flow;
> + struct nf_conn *ct;
> + unsigned int thoff;
> + int ip_proto;
> + u8 dir;
> +
> + /* Previously seen or loopback */
> + ct = nf_ct_get(skb, &ctinfo);
> + if ((ct && !nf_ct_is_template(ct)) || ctinfo == IP_CT_UNTRACKED)
> + return false;
> +
> + switch (family) {
> + case NFPROTO_IPV4:
> + if (!tcf_ct_flow_table_fill_tuple_ipv4(skb, &tuple))
> + return false;
> + break;
> + case NFPROTO_IPV6:
> + if (!tcf_ct_flow_table_fill_tuple_ipv6(skb, &tuple))
> + return false;
> + break;
> + default:
> + return false;
> + }
> +
> + tuplehash = flow_offload_lookup(nf_ft, &tuple);
> + if (!tuplehash)
> + return false;
> +
> + dir = tuplehash->tuple.dir;
> + flow = container_of(tuplehash, struct flow_offload, tuplehash[dir]);
> + ct = flow->ct;
> +
> + ctinfo = dir == FLOW_OFFLOAD_DIR_ORIGINAL ? IP_CT_ESTABLISHED :
> + IP_CT_ESTABLISHED_REPLY;
> +
> + thoff = ip_hdr(skb)->ihl * 4;
> + ip_proto = ip_hdr(skb)->protocol;
I'm a bit confused about this part, above you treat the skb based on the family
but down here it's always IPv4 ?
> + if (ip_proto == IPPROTO_TCP &&
> + !tcf_ct_flow_table_check_tcp(flow, skb, thoff))
> + return false;
> +
> + nf_conntrack_get(&ct->ct_general);
> + nf_ct_set(skb, ct, ctinfo);
> +
> + return true;
> +}
> +
> static int tcf_ct_flow_tables_init(void)
> {
> return rhashtable_init(&zones_ht, &zones_params);
> @@ -554,6 +705,7 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
> struct nf_hook_state state;
> int nh_ofs, err, retval;
> struct tcf_ct_params *p;
> + bool skip_add = false;
> struct nf_conn *ct;
> u8 family;
>
> @@ -603,6 +755,11 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
> */
> cached = tcf_ct_skb_nfct_cached(net, skb, p->zone, force);
> if (!cached) {
> + if (!commit && tcf_ct_flow_table_lookup(p, skb, family)) {
> + skip_add = true;
> + goto do_nat;
> + }
> +
> /* Associate skb with specified zone. */
> if (tmpl) {
> ct = nf_ct_get(skb, &ctinfo);
> @@ -620,6 +777,7 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
> goto out_push;
> }
>
> +do_nat:
> ct = nf_ct_get(skb, &ctinfo);
> if (!ct)
> goto out_push;
> @@ -637,10 +795,10 @@ static int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
> * even if the connection is already confirmed.
> */
> nf_conntrack_confirm(skb);
> + } else if (!skip_add) {
> + tcf_ct_flow_table_process_conn(p->ct_ft, ct, ctinfo);
> }
>
> - tcf_ct_flow_table_process_conn(p->ct_ft, ct, ctinfo);
> -
> out_push:
> skb_push_rcsum(skb, nh_ofs);
>
>
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