6b5291654f
nfacct is netfilter's accounting subsystem. This utility allows interactions with the subsystem using lower level netlink API. Signed-off-by: Daman Arora <aroradaman@gmail.com>
84 lines
2.6 KiB
Go
84 lines
2.6 KiB
Go
//go:build linux
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// +build linux
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/*
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Copyright 2024 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package nfacct
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import (
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"github.com/vishvananda/netlink/nl"
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"github.com/vishvananda/netns"
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"golang.org/x/sys/unix"
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)
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// handler is an injectable interface for creating netlink request.
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type handler interface {
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newRequest(cmd int, flags uint16) request
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}
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// request is an injectable interface representing a netlink request.
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type request interface {
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Serialize() []byte
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AddData(data nl.NetlinkRequestData)
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AddRawData(data []byte)
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Execute(sockType int, resType uint16) ([][]byte, error)
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}
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// netlinkHandler is an implementation of the handler interface. It maintains a netlink socket
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// for communication with the NFAcct subsystem.
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type netlinkHandler struct {
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socket *nl.NetlinkSocket
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}
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// newNetlinkHandler initializes a netlink socket in the current network namespace and returns
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// an instance of netlinkHandler with the initialized socket.
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func newNetlinkHandler() (handler, error) {
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socket, err := nl.GetNetlinkSocketAt(netns.None(), netns.None(), unix.NETLINK_NETFILTER)
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if err != nil {
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return nil, err
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}
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return &netlinkHandler{socket: socket}, nil
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}
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// newRequest creates a netlink request tailored for the NFAcct subsystem encapsulating the
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// specified cmd and flags. It incorporates the netlink header and netfilter generic header
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// into the resulting request.
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func (n *netlinkHandler) newRequest(cmd int, flags uint16) request {
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req := &nl.NetlinkRequest{
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// netlink message header
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// (definition: https://github.com/torvalds/linux/blob/v6.7/include/uapi/linux/netlink.h#L44-L58)
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NlMsghdr: unix.NlMsghdr{
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Len: uint32(unix.SizeofNlMsghdr),
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Type: uint16(cmd | (unix.NFNL_SUBSYS_ACCT << 8)),
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Flags: flags,
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},
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Sockets: map[int]*nl.SocketHandle{
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unix.NETLINK_NETFILTER: {Socket: n.socket},
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},
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Data: []nl.NetlinkRequestData{
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// netfilter generic message
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// (definition: https://github.com/torvalds/linux/blob/v6.7/include/uapi/linux/netfilter/nfnetlink.h#L32-L38)
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&nl.Nfgenmsg{
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NfgenFamily: uint8(unix.AF_NETLINK),
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Version: nl.NFNETLINK_V0,
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ResId: 0,
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},
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},
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}
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return req
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}
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