[v1.15] Multicast Datapath Backport #31668

[ upstream commit b7822a3 ] This commit adds the eBPF map used to implement the synthetic multicast feature. A `BPF_MAP_TYPE_HASH_OF_MAPS`, which employees a `BPF_MAP_TYPE_HASH` inner map, is added to the datapath. The outer eBPF map is keyed by IPv4 multicast group addresses in big endian format and the values are `BPF_MAP_TYPE_HASH` maps. The inner hash map associates IPv4 source addresses with their subscriber multicast metadata. Each key/value in the inner hash map is a subscriber of the owning multicast group. Signed-off-by: Louis DeLosSantos <louis.delos@isovalent.com>

[ upstream commit d7e580f ] This commit introduces IGMPv3 detection and parsing. When bpf_lxc recognizes IGMP messages egressing the Pod we attempt to parse them. The parsing logic is as follows: 1. Determine if traffic is IGMP 2. Determine the IGMP message type 3. If the type is not a membership report simply drop it (for now) 4. Parse each group record in the membership report 5. For any group records which indicate a join add a subscriber to the multicast subscriber map, if it exists. Signed-off-by: Louis DeLosSantos <louis.delos@isovalent.com>

[ upstream commit 8c488dd ] This commit adds parsing of IGMPv2 messages in a similar fashion as IGMPv3 messages. Signed-off-by: Louis DeLosSantos <louis.delos@isovalent.com>

[ upstream commit 2afcb61 ] This commit implements replication and delivery of multicast packets. This commit also enables the Cilium datapath to access both `bpf_clone_redirect` and `bpf_map_for_each_elem` helpers. The datapath flow is illustrated below: ┌──────────────────────────────────────────┐ │ │ │ Sender │ │ ┌──────┐ ┌─────────┐ │ │ │ pod ├─────► bpf_lxc │ │ │ └──────┘ └────┬────┘ │ │ Local Receivers │ eBPF Replication │ │ ┌──────┐ ┌──────┐ │ and Redirection │ │ │ pod ◄─┤ veth ◄─┤(cil_from_container) │ │ └──────┘ └──────┘ │ ┌───────┐ │ │ ├─► vxlan │ │ │ ┌──────┐ ┌──────┐ │ └───┬───┘ │ │ │ pod ◄─┤ veth ◄─┘ │ │ │ └──────┘ └──────┘ ┌────┘ │ │ │ │ └─────────────────────┼────────────────────┘ │ ┌─────────────────────┼────────────────────┐ │ │ │ │ ┌───▼───┐ │ │ │ vxlan │ │ │ └───┬───┘ │ │ Remote Receivers │ eBPF Replication │ │ ┌──────┐ ┌──────┐ │ and Redirection │ │ │ pod ◄─┤ veth ◄─┤ (from_overlay) │ │ └──────┘ └──────┘ │ │ │ │ │ │ ┌──────┐ ┌──────┐ │ │ │ │ pod ◄─┤ veth ◄─┘ │ │ └──────┘ └──────┘ │ │ │ └──────────────────────────────────────────┘ A multicast sender sends a multicast packet. The sender's bpf_lxc program does a lookup in the multicast group map to discover who has subscribed to the group. The program then clones and redirects the packets to the subscriber's ingress device on the host namespace. If the subscriber is remote the packet is cloned and redirected to a vxlan device for encapsulation. Once the host stack forwards the vxlan encap'd packet to the receiving vxlan device on the remote host a similar "clone and redirect" process is performed once the vxlan driver decaps the packet. Signed-off-by: Louis DeLosSantos <louis.delos@isovalent.com>

Signed-off-by: Louis DeLosSantos <louis.delos@isovalent.com>

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[v1.15] Multicast Datapath Backport #31668

[v1.15] Multicast Datapath Backport #31668

Commits on Mar 29, 2024