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Date: Fri, 31 Jul 2015 19:08:07 -0700
From: Pravin Shelar <pshelar@...ira.com>
To: Joe Stringer <joestringer@...ira.com>
Cc: netdev <netdev@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>, pablo <pablo@...filter.org>,
Patrick McHardy <kaber@...sh.net>,
Justin Pettit <jpettit@...ira.com>,
Andy Zhou <azhou@...ira.com>, Jesse Gross <jesse@...ira.com>,
Florian Westphal <fwestpha@...hat.com>,
Hannes Sowa <hannes@...hat.com>,
Thomas Graf <tgraf@...ronetworks.com>
Subject: Re: [PATCH net-next 5/9] openvswitch: Add conntrack action
On Thu, Jul 30, 2015 at 11:12 AM, Joe Stringer <joestringer@...ira.com> wrote:
> Expose the kernel connection tracker via OVS. Userspace components can
> make use of the "ct()" action, followed by "recirculate", to populate
> the conntracking state in the OVS flow key, and subsequently match on
> that state.
>
> Example ODP flows allowing traffic from 1->2, only replies from 2->1:
> in_port=1,tcp,action=ct(commit,zone=1),2
> in_port=2,ct_state=-trk,tcp,action=ct(zone=1),recirc(1)
> recirc_id=1,in_port=2,ct_state=+trk+est-new,tcp,action=1
>
> IP fragments are handled by transparently assembling them as part of the
> ct action. The maximum received unit (MRU) size is tracked so that
> refragmentation can occur during output.
>
> IP frag handling contributed by Andy Zhou.
>
> Signed-off-by: Joe Stringer <joestringer@...ira.com>
> Signed-off-by: Justin Pettit <jpettit@...ira.com>
> Signed-off-by: Andy Zhou <azhou@...ira.com>
> ---
> This can be tested with the corresponding userspace component here:
> https://www.github.com/justinpettit/openvswitch conntrack
> ---
> include/uapi/linux/openvswitch.h | 41 ++++
> net/openvswitch/Kconfig | 11 +
> net/openvswitch/Makefile | 1 +
> net/openvswitch/actions.c | 162 ++++++++++++-
> net/openvswitch/conntrack.c | 480 +++++++++++++++++++++++++++++++++++++++
> net/openvswitch/conntrack.h | 82 +++++++
> net/openvswitch/datapath.c | 62 +++--
> net/openvswitch/datapath.h | 6 +
> net/openvswitch/flow.c | 3 +
> net/openvswitch/flow.h | 6 +
> net/openvswitch/flow_netlink.c | 73 ++++--
> net/openvswitch/flow_netlink.h | 4 +-
> net/openvswitch/vport.c | 1 +
> 13 files changed, 897 insertions(+), 35 deletions(-)
> create mode 100644 net/openvswitch/conntrack.c
> create mode 100644 net/openvswitch/conntrack.h
>
...
> diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
> index e50678d..4a62ed4 100644
> --- a/net/openvswitch/actions.c
> +++ b/net/openvswitch/actions.c
> @@ -22,6 +22,7 @@
> #include <linux/in.h>
> #include <linux/ip.h>
..
> static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
> @@ -52,6 +55,16 @@ struct deferred_action {
> struct sw_flow_key pkt_key;
> };
>
> +struct ovs_frag_data {
> + struct dst_entry *dst;
> + struct vport *vport;
> + struct sw_flow_key *key;
> + struct ovs_skb_cb cb;
> + __be16 vlan_proto;
> +};
> +
> +static DEFINE_PER_CPU(struct ovs_frag_data, ovs_frag_data_storage);
> +
> #define DEFERRED_ACTION_FIFO_SIZE 10
> struct action_fifo {
> int head;
> @@ -594,14 +607,136 @@ static int set_sctp(struct sk_buff *skb, struct sw_flow_key *flow_key,
> return 0;
> }
>
> -static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port)
> +/* Given an IP frame, reconstruct its MAC header. */
> +static void ovs_setup_l2_header(struct sk_buff *skb,
> + const struct ovs_frag_data *data)
> +{
> + struct sw_flow_key *key = data->key;
> +
> + skb_push(skb, ETH_HLEN);
> + skb_reset_mac_header(skb);
> +
> + ether_addr_copy(eth_hdr(skb)->h_source, key->eth.src);
> + ether_addr_copy(eth_hdr(skb)->h_dest, key->eth.dst);
> + eth_hdr(skb)->h_proto = key->eth.type;
> +
> + if ((data->key->eth.tci & htons(VLAN_TAG_PRESENT)) &&
> + !skb_vlan_tag_present(skb))
> + __vlan_hwaccel_put_tag(skb, data->vlan_proto,
> + ntohs(key->eth.tci));
> +}
> +
> +static void prepare_frag(struct vport *vport, struct sw_flow_key *key,
> + struct sk_buff *skb)
> +{
> + unsigned int hlen = ETH_HLEN;
> + struct ovs_frag_data *data;
> +
> + data = this_cpu_ptr(&ovs_frag_data_storage);
> + data->dst = skb_dst(skb);
> + data->vport = vport;
> + data->key = key;
> + data->cb = *OVS_CB(skb);
> +
> + if (key->eth.tci & htons(VLAN_TAG_PRESENT)) {
> + if (skb_vlan_tag_present(skb)) {
> + data->vlan_proto = skb->vlan_proto;
> + } else {
> + data->vlan_proto = vlan_eth_hdr(skb)->h_vlan_proto;
> + hlen += VLAN_HLEN;
> + }
> + }
Not all actions keep flow key uptodate, so here you can access stale values.
> +
> + memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
> + skb_pull(skb, hlen);
> +}
> +
> +static int ovs_vport_output(struct sock *sock, struct sk_buff *skb)
> +{
> + struct ovs_frag_data *data = this_cpu_ptr(&ovs_frag_data_storage);
> + struct vport *vport = data->vport;
> +
> + skb_dst_drop(skb);
> + skb_dst_set(skb, dst_clone(data->dst));
> + *OVS_CB(skb) = data->cb;
> +
> + ovs_setup_l2_header(skb, data);
> + ovs_vport_send(vport, skb);
> +
> + return 0;
> +}
> +
...
> +static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
> + struct sw_flow_key *key)
> {
> struct vport *vport = ovs_vport_rcu(dp, out_port);
>
> - if (likely(vport))
> - ovs_vport_send(vport, skb);
> - else
> + if (likely(vport)) {
> + unsigned int mru = OVS_CB(skb)->mru;
> + struct dst_entry *orig_dst = dst_clone(skb_dst(skb));
> +
> + if (!mru || (skb->len <= mru + ETH_HLEN)) {
This should be marked as likely() case.
> + ovs_vport_send(vport, skb);
> + } else if (!vport->dev) {
> + WARN_ONCE(1, "Cannot fragment packets to vport %s\n",
> + vport->ops->get_name(vport));
> + kfree_skb(skb);
> + } else if (mru > vport->dev->mtu) {
> + kfree_skb(skb);
> + } else if (key->eth.type == htons(ETH_P_IP)) {
> + struct dst_entry ovs_dst;
> +
> + prepare_frag(vport, key, skb);
> + dst_init(&ovs_dst, &ovs_dst_ops, vport->dev,
> + 1, DST_OBSOLETE_NONE, DST_NOCOUNT);
> +
> + skb_dst_drop(skb);
> + skb_dst_set_noref(skb, &ovs_dst);
> + IPCB(skb)->frag_max_size = mru;
> +
> + ip_do_fragment(skb->sk, skb, ovs_vport_output);
> + dev_put(ovs_dst.dev);
> + } else if (key->eth.type == htons(ETH_P_IPV6)) {
> + const struct nf_ipv6_ops *v6ops = nf_get_ipv6_ops();
> + struct rt6_info ovs_rt;
> +
> + if (!v6ops) {
> + kfree_skb(skb);
> + goto exit;
> + }
> +
> + prepare_frag(vport, key, skb);
> + memset(&ovs_rt, 0, sizeof(ovs_rt));
> + dst_init(&ovs_rt.dst, &ovs_dst_ops, vport->dev,
> + 1, DST_OBSOLETE_NONE, DST_NOCOUNT);
> +
> + skb_dst_drop(skb);
> + skb_dst_set_noref(skb, &ovs_rt.dst);
> + IP6CB(skb)->frag_max_size = mru;
> +
> + v6ops->fragment(skb->sk, skb, ovs_vport_output);
> + dev_put(ovs_rt.dst.dev);
> + } else {
> + WARN_ONCE(1, "Failed fragment to %s: MRU=%d, MTU=%d.",
> + ovs_vport_name(vport), mru, vport->dev->mtu);
It would be helpful if the msg also mentions key->eth.type.
> + kfree_skb(skb);
> + }
> +exit:
> + dst_release(orig_dst);
> + } else {
> kfree_skb(skb);
> + }
> }
>
> static int output_userspace(struct datapath *dp, struct sk_buff *skb,
> @@ -615,6 +750,10 @@ static int output_userspace(struct datapath *dp, struct sk_buff *skb,
>
> memset(&upcall, 0, sizeof(upcall));
> upcall.cmd = OVS_PACKET_CMD_ACTION;
> + upcall.userdata = NULL;
> + upcall.portid = 0;
> + upcall.egress_tun_info = NULL;
> + upcall.mru = OVS_CB(skb)->mru;
>
> for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
> a = nla_next(a, &rem)) {
> @@ -874,7 +1013,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
> struct sk_buff *out_skb = skb_clone(skb, GFP_ATOMIC);
>
> if (out_skb)
> - do_output(dp, out_skb, prev_port);
> + do_output(dp, out_skb, prev_port, key);
>
> prev_port = -1;
> }
> @@ -931,16 +1070,25 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
> case OVS_ACTION_ATTR_SAMPLE:
> err = sample(dp, skb, key, a, attr, len);
> break;
> +
> + case OVS_ACTION_ATTR_CT:
> + err = ovs_ct_execute(skb, key, nla_data(a));
> + break;
> }
>
> if (unlikely(err)) {
> - kfree_skb(skb);
> + /* Hide stolen fragments from user space. */
> + if (err == -EINPROGRESS)
> + err = 0;
This does not look safe for error returned from all cases, Can you
check this case specifically for the CT action case.
> + else
> + kfree_skb(skb);
> +
> return err;
> }
> }
>
> if (prev_port != -1)
> - do_output(dp, skb, prev_port);
> + do_output(dp, skb, prev_port, key);
> else
> consume_skb(skb);
>
> diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
> new file mode 100644
> index 0000000..284b89e
> --- /dev/null
> +++ b/net/openvswitch/conntrack.c
> @@ -0,0 +1,480 @@
...
> +
> +static struct net *ovs_get_net(const struct sk_buff *skb)
> +{
> + struct vport *vport;
> +
> + vport = OVS_CB(skb)->input_vport;
> + if (!vport) {
I do not think this is possible, OVS always initialize input_vport.
> + WARN_ONCE(1, "Can't obtain netns from vport");
> + return ERR_PTR(-EINVAL);
> + }
> +
> + return read_pnet(&vport->dp->net);
> +}
> +
...
> +
> +static inline void ovs_ct_free_action(const struct nlattr *a) { }
> +#endif
> +#endif /* ovs_conntrack.h */
> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> index d5b5473..23717a3 100644
> --- a/net/openvswitch/datapath.c
> +++ b/net/openvswitch/datapath.c
> @@ -275,6 +275,8 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
> memset(&upcall, 0, sizeof(upcall));
> upcall.cmd = OVS_PACKET_CMD_MISS;
> upcall.portid = ovs_vport_find_upcall_portid(p, skb);
> + upcall.egress_tun_info = NULL;
There is no need to set egress_tun_info to NULL.
> + upcall.mru = OVS_CB(skb)->mru;
> error = ovs_dp_upcall(dp, skb, key, &upcall);
> if (unlikely(error))
> kfree_skb(skb);
> @@ -400,9 +402,23 @@ static size_t upcall_msg_size(const struct dp_upcall_info *upcall_info,
--
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