Family ovs_packet netlink specification

Summary

OVS packet execution over generic netlink.

Only OVS_PACKET_CMD_EXECUTE is exposed as a genl operation. OVS_PACKET_CMD_MISS and OVS_PACKET_CMD_ACTION are kernel-to-userspace upcalls sent via genlmsg_unicast() to the vport’s upcall_pid and have no associated genl_ops or multicast group.

Several attributes in the attribute set (userdata, egress-tun-key, len) exist for the upcall path and are not used by the EXECUTE operation. For EXECUTE, packet, key, and actions are mandatory (kernel returns -EINVAL without them).

Operations

miss

Notify userspace of a flow table miss for a received packet.

value:

1

attribute-set:

packet

event:

attributes:

[packet, key, userdata, actions, egress-tun-key, mru, len, hash]

action

Notify userspace as requested by an OVS_ACTION_ATTR_USERSPACE action.

value:

2

attribute-set:

packet

event:

attributes:

[packet, key, userdata, actions, egress-tun-key, mru, len, hash]

execute

Apply actions to a packet.

value:

3

attribute-set:

packet

do:

request

attributes:

[packet, key, actions, probe, mru, hash, upcall-pid]

Definitions

ovs-header

type:

struct

members:

dp-ifindex (u32):

Attribute sets

packet

packet (binary)

doc:

Packet data, from the start of the Ethernet header.

key (binary)

doc:

Nested OVS_KEY_ATTR_* attributes, extracted flow key. Defined as binary because the key attribute-set belongs to the ovs_flow family spec; cross-spec references are not supported.

actions (binary)

doc:

Nested OVS_ACTION_ATTR_* attributes. Defined as binary for the same reason as key.

userdata (binary)

doc:

Opaque userspace cookie from OVS_USERSPACE_ATTR_USERDATA.

egress-tun-key (binary)

doc:

Nested OVS_TUNNEL_KEY_ATTR_* for output tunnel metadata.

unused1 (unused)

unused2 (unused)

probe (flag)

doc:

Packet operation is a feature probe, error logging suppressed.

mru (u16)

doc:

Maximum received IP fragment size.

len (u32)

doc:

Packet size before truncation.

hash (u64)

doc:

Packet hash, low 32 bits are skb hash, upper bits are flags.

upcall-pid (u32)

doc:

Netlink PID to use for upcalls during EXECUTE processing.