Re: [dpdk-dev] [PATCH v2 1/2] ethdev: introduce conntrack flow action and item

[Ori Kam <orika@nvidia.com>]

Hi Bing,

One more thought, PSB

Best,
Ori
> -----Original Message-----
> From: Bing Zhao <bingz@nvidia.com>
> Sent: Thursday, April 15, 2021 7:41 PM
> To: Ori Kam <orika@nvidia.com>; NBU-Contact-Thomas Monjalon
> <thomas@monjalon.net>; ferruh.yigit@intel.com;
> andrew.rybchenko@oktetlabs.ru
> Cc: dev@dpdk.org; ajit.khaparde@broadcom.com
> Subject: [PATCH v2 1/2] ethdev: introduce conntrack flow action and item
> 
> This commit introduced the conntrack action and item.
> 
> Usually the HW offloading is stateless. For some stateful offloading
> like a TCP connection, HW module will help provide the ability of a
> full offloading w/o SW participation after the connection was
> established.
> 
> The basic usage is that in the first flow the application should add
> the conntrack action and in the following flow(s) the application
> should use the conntrack item to match on the result.
> 
> A TCP connection has two directions traffic. To set a conntrack
> action context correctly, information from packets of both directions
> are required.
> 
> The conntrack action should be created on one port and supply the
> peer port as a parameter to the action. After context creating, it
> could only be used between the ports (dual-port mode) or a single
> port. The application should modify the action via the API
> "action_handle_update" only when before using it to create a flow
> with opposite direction. This will help the driver to recognize the
> direction of the flow to be created, especially in single port mode.
> The traffic from both directions will go through the same port if
> the application works as an "forwarding engine" but not a end point.
> There is no need to call the update interface if the subsequent flows
> have nothing to be changed.
> 
> Query will be supported via action_ctx_query interface, about the
> current packets information and connection status. Tha fields
> query capabilities depends on the HW.
> 
> For the packets received during the conntrack setup, it is suggested
> to re-inject the packets in order to take full advantage of the
> conntrack. Only the valid packets should pass the conntrack, packets
> with invalid TCP information, like out of window, or with invalid
> header, like malformed, should not pass.
> 
> Naming and definition:
> https://elixir.bootlin.com/linux/latest/source/include/uapi/linux/netfilter/nf_co
> nntrack_tcp.h
> https://elixir.bootlin.com/linux/latest/source/net/netfilter/nf_conntrack_proto_
> tcp.c
> 
> Other reference:
> https://www.usenix.org/legacy/events/sec01/invitedtalks/rooij.pdf
> 
> Signed-off-by: Bing Zhao <bingz@nvidia.com>
> ---
>  lib/librte_ethdev/rte_flow.c |   2 +
>  lib/librte_ethdev/rte_flow.h | 195 +++++++++++++++++++++++++++++++++++
>  2 files changed, 197 insertions(+)
> 
> diff --git a/lib/librte_ethdev/rte_flow.c b/lib/librte_ethdev/rte_flow.c
> index 27a161559d..0af601d508 100644
> --- a/lib/librte_ethdev/rte_flow.c
> +++ b/lib/librte_ethdev/rte_flow.c
> @@ -98,6 +98,7 @@ static const struct rte_flow_desc_data
> rte_flow_desc_item[] = {
>  	MK_FLOW_ITEM(PFCP, sizeof(struct rte_flow_item_pfcp)),
>  	MK_FLOW_ITEM(ECPRI, sizeof(struct rte_flow_item_ecpri)),
>  	MK_FLOW_ITEM(GENEVE_OPT, sizeof(struct
> rte_flow_item_geneve_opt)),
> +	MK_FLOW_ITEM(CONNTRACK, sizeof(uint32_t)),
>  };
> 
>  /** Generate flow_action[] entry. */
> @@ -186,6 +187,7 @@ static const struct rte_flow_desc_data
> rte_flow_desc_action[] = {
>  	 * indirect action handle.
>  	 */
>  	MK_FLOW_ACTION(INDIRECT, 0),
> +	MK_FLOW_ACTION(CONNTRACK, sizeof(struct
> rte_flow_action_conntrack)),
>  };
> 
>  int
> diff --git a/lib/librte_ethdev/rte_flow.h b/lib/librte_ethdev/rte_flow.h
> index 91ae25b1da..024d1a2026 100644
> --- a/lib/librte_ethdev/rte_flow.h
> +++ b/lib/librte_ethdev/rte_flow.h
> @@ -551,6 +551,15 @@ enum rte_flow_item_type {
>  	 * See struct rte_flow_item_geneve_opt
>  	 */
>  	RTE_FLOW_ITEM_TYPE_GENEVE_OPT,
> +
> +	/**
> +	 * [META]
> +	 *
> +	 * Matches conntrack state.
> +	 *
> +	 * See struct rte_flow_item_conntrack.
> +	 */
> +	RTE_FLOW_ITEM_TYPE_CONNTRACK,
>  };
> 
>  /**
> @@ -1685,6 +1694,51 @@ rte_flow_item_geneve_opt_mask = {
>  };
>  #endif
> 
> +/**
> + * The packet is with valid state after conntrack checking.
> + */
> +#define RTE_FLOW_CONNTRACK_FLAG_PKT_STATE_VALID (1 << 0)
> +/**
> + * The state of the connection was changed.
> + */
> +#define RTE_FLOW_CONNTRACK_FLAG_PKT_STATE_CHANGED (1 << 1)
> +/**
> + * Error is detected on this packet for this connection and
> + * an invalid state is set.
> + */
> +#define RTE_FLOW_CONNTRACK_FLAG_PKT_STATE_INVAL (1 << 2)
> +/**
> + * The HW connection tracking module is disabled.
> + * It can be due to application command or an invalid state.
> + */
> +#define RTE_FLOW_CONNTRACK_FLAG_HW_DISABLED (1 << 3)
> +/**
> + * The packet contains some bad field(s) and cannot continue
> + * with the conntrack module checking.
> + */
> +#define RTE_FLOW_CONNTRACK_FLAG_PKT_BAD (1 << 4)
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this structure may change without prior notice
> + *
> + * RTE_FLOW_ITEM_TYPE_CONNTRACK
> + *
> + * Matches the state of a packet after it passed the connection tracking
> + * examination. The state is a bit mask of one RTE_FLOW_CONNTRACK_FLAG*
> + * or a reasonable combination of these bits.
> + */
> +struct rte_flow_item_conntrack {
> +	uint32_t flags;
> +};
> +
> +/** Default mask for RTE_FLOW_ITEM_TYPE_CONNTRACK. */
> +#ifndef __cplusplus
> +static const struct rte_flow_item_conntrack rte_flow_item_conntrack_mask =
> {
> +	.flags = 0xffffffff,
> +};
> +#endif
> +
>  /**
>   * Matching pattern item definition.
>   *
> @@ -2277,6 +2331,17 @@ enum rte_flow_action_type {
>  	 * same port or across different ports.
>  	 */
>  	RTE_FLOW_ACTION_TYPE_INDIRECT,
> +
> +	/**
> +	 * [META]
> +	 *
> +	 * Enable tracking a TCP connection state.
> +	 *
> +	 * Send packet to HW connection tracking module for examination.
> +	 *
> +	 * See struct rte_flow_action_conntrack.
> +	 */
> +	RTE_FLOW_ACTION_TYPE_CONNTRACK,
>  };
> 
>  /**
> @@ -2875,6 +2940,136 @@ struct rte_flow_action_set_dscp {
>   */
>  struct rte_flow_action_handle;
> 
> +/**
> + * The state of a TCP connection.
> + */
> +enum rte_flow_conntrack_state {
> +	/**< SYN-ACK packet was seen. */
> +	RTE_FLOW_CONNTRACK_STATE_SYN_RECV,
> +	/**< 3-way handshark was done. */
> +	RTE_FLOW_CONNTRACK_STATE_ESTABLISHED,
> +	/**< First FIN packet was received to close the connection. */
> +	RTE_FLOW_CONNTRACK_STATE_FIN_WAIT,
> +	/**< First FIN was ACKed. */
> +	RTE_FLOW_CONNTRACK_STATE_CLOSE_WAIT,
> +	/**< Second FIN was received, waiting for the last ACK. */
> +	RTE_FLOW_CONNTRACK_STATE_LAST_ACK,
> +	/**< Second FIN was ACKed, connection was closed. */
> +	RTE_FLOW_CONNTRACK_STATE_TIME_WAIT,
> +};
> +
> +/**
> + * The last passed TCP packet flags of a connection.
> + */
> +enum rte_flow_conntrack_tcp_last_index {
> +	RTE_FLOW_CONNTRACK_FLAG_NONE = 0, /**< No Flag. */
> +	RTE_FLOW_CONNTRACK_FLAG_SYN = (1 << 0), /**< With SYN flag. */
> +	RTE_FLOW_CONNTRACK_FLAG_SYNACK = (1 << 1), /**< With SYN+ACK
> flag. */
> +	RTE_FLOW_CONNTRACK_FLAG_FIN = (1 << 2), /**< With FIN flag. */
> +	RTE_FLOW_CONNTRACK_FLAG_ACK = (1 << 3), /**< With ACK flag. */
> +	RTE_FLOW_CONNTRACK_FLAG_RST = (1 << 4), /**< With RST flag. */
> +};
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this structure may change without prior notice
> + *
> + * Configuration parameters for each direction of a TCP connection.
> + */
> +struct rte_flow_tcp_dir_param {
> +	uint32_t scale:4; /**< TCP window scaling factor, 0xF to disable. */
> +	uint32_t close_initiated:1; /**< The FIN was sent by this direction. */
> +	/**< An ACK packet has been received by this side. */
> +	uint32_t last_ack_seen:1;
> +	/**< If set, indicates that there is unacked data of the connection. */
> +	uint32_t data_unacked:1;
> +	/**< Maximal value of sequence + payload length over sent
> +	 * packets (next ACK from the opposite direction).
> +	 */
> +	uint32_t sent_end;
> +	/**< Maximal value of (ACK + window size) over received packet +
> length
> +	 * over sent packet (maximal sequence could be sent).
> +	 */
> +	uint32_t reply_end;

This comment is for all members that are part of the packet,
Do you think it should be in network order?
I can see the advantage in both ways nice I assume the app needs this data 
in host byte-order  but since in most other cases we use network byte-order to 
set values that are coming from the packet itself maybe it is better to use network
byte-order (will also save the conversion)

> +	/**< Maximal value of actual window size over sent packets. */
> +	uint32_t max_win;
> +	/**< Maximal value of ACK over sent packets. */
> +	uint32_t max_ack;
> +};
> +
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this structure may change without prior notice
> + *
> + * RTE_FLOW_ACTION_TYPE_CONNTRACK
> + *
> + * Configuration and initial state for the connection tracking module.
> + * This structure could be used for both setting and query.
> + */
> +struct rte_flow_action_conntrack {
> +	uint16_t peer_port; /**< The peer port number, can be the same port.
> */
> +	/**< Direction of this connection when creating a flow, the value only
> +	 * affects the subsequent flows creation.
> +	 */
> +	uint32_t is_original_dir:1;
> +	/**< Enable / disable the conntrack HW module. When disabled, the
> +	 * result will always be RTE_FLOW_CONNTRACK_FLAG_DISABLED.
> +	 * In this state the HW will act as passthrough.
> +	 * It only affects this conntrack object in the HW without any effect
> +	 * to the other objects.
> +	 */
> +	uint32_t enable:1;
> +	/**< At least one ack was seen, after the connection was established.
> */
> +	uint32_t live_connection:1;
> +	/**< Enable selective ACK on this connection. */
> +	uint32_t selective_ack:1;
> +	/**< A challenge ack has passed. */
> +	uint32_t challenge_ack_passed:1;
> +	/**< 1: The last packet is seen that comes from the original direction.
> +	 * 0: From the reply direction.
> +	 */
> +	uint32_t last_direction:1;
> +	/**< No TCP check will be done except the state change. */
> +	uint32_t liberal_mode:1;
> +	/**< The current state of the connection. */
> +	enum rte_flow_conntrack_state state;
> +	/**< Scaling factor for maximal allowed ACK window. */
> +	uint8_t max_ack_window;
> +	/**< Maximal allowed number of retransmission times. */
> +	uint8_t retransmission_limit;
> +	/**< TCP parameters of the original direction. */
> +	struct rte_flow_tcp_dir_param original_dir;
> +	/**< TCP parameters of the reply direction. */
> +	struct rte_flow_tcp_dir_param reply_dir;
> +	/**< The window value of the last packet passed this conntrack. */
> +	uint16_t last_window;
> +	enum rte_flow_conntrack_tcp_last_index last_index;
> +	/**< The sequence of the last packet passed this conntrack. */
> +	uint32_t last_seq;
> +	/**< The acknowledgement of the last packet passed this conntrack. */
> +	uint32_t last_ack;
> +	/**< The total value ACK + payload length of the last packet passed
> +	 * this conntrack.
> +	 */
> +	uint32_t last_end;
> +};
> +
> +/**
> + * RTE_FLOW_ACTION_TYPE_CONNTRACK
> + *
> + * Wrapper structure for the context update interface.
> + * Ports cannot support updating, and the only valid solution is to
> + * destroy the old context and create a new one instead.
> + */
> +struct rte_flow_modify_conntrack {
> +	/**< New connection tracking parameters to be updated. */
> +	struct rte_flow_action_conntrack new_ct;
> +	uint32_t direction:1; /**< The direction field will be updated. */
> +	/**< All the other fields except direction will be updated. */
> +	uint32_t state:1;
> +	uint32_t reserved:30; /**< Reserved bits for the future usage. */
> +};
> +
>  /**
>   * Field IDs for MODIFY_FIELD action.
>   */
> --
> 2.19.0.windows.1