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feat: add monitor on table chain rule set setelem and obj events (#250)
fixes #224
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module github.com/google/nftables | ||
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go 1.17 | ||
go 1.18 | ||
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require ( | ||
github.com/mdlayher/netlink v1.7.1 | ||
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// Copyright 2018 Google LLC. All Rights Reserved. | ||
// | ||
// Licensed under the Apache License, Version 2.0 (the "License"); | ||
// you may not use this file except in compliance with the License. | ||
// You may obtain a copy of the License at | ||
// | ||
// http://www.apache.org/licenses/LICENSE-2.0 | ||
// | ||
// Unless required by applicable law or agreed to in writing, software | ||
// distributed under the License is distributed on an "AS IS" BASIS, | ||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
// See the License for the specific language governing permissions and | ||
// limitations under the License. | ||
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package nftables | ||
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import ( | ||
"math" | ||
"strings" | ||
"sync" | ||
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"github.com/mdlayher/netlink" | ||
"golang.org/x/sys/unix" | ||
) | ||
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type MonitorAction uint8 | ||
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// Possible MonitorAction values. | ||
const ( | ||
MonitorActionNew MonitorAction = 1 << iota | ||
MonitorActionDel | ||
MonitorActionMask MonitorAction = (1 << iota) - 1 | ||
MonitorActionAny MonitorAction = MonitorActionMask | ||
) | ||
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type MonitorObject uint32 | ||
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// Possible MonitorObject values. | ||
const ( | ||
MonitorObjectTables MonitorObject = 1 << iota | ||
MonitorObjectChains | ||
MonitorObjectSets | ||
MonitorObjectRules | ||
MonitorObjectElements | ||
MonitorObjectRuleset | ||
MonitorObjectMask MonitorObject = (1 << iota) - 1 | ||
MonitorObjectAny MonitorObject = MonitorObjectMask | ||
) | ||
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var ( | ||
monitorFlags = map[MonitorAction]map[MonitorObject]uint32{ | ||
MonitorActionAny: { | ||
MonitorObjectAny: 0xffffffff, | ||
MonitorObjectTables: 1<<unix.NFT_MSG_NEWTABLE | 1<<unix.NFT_MSG_DELTABLE, | ||
MonitorObjectChains: 1<<unix.NFT_MSG_NEWCHAIN | 1<<unix.NFT_MSG_DELCHAIN, | ||
MonitorObjectRules: 1<<unix.NFT_MSG_NEWRULE | 1<<unix.NFT_MSG_DELRULE, | ||
MonitorObjectSets: 1<<unix.NFT_MSG_NEWSET | 1<<unix.NFT_MSG_DELSET, | ||
MonitorObjectElements: 1<<unix.NFT_MSG_NEWSETELEM | 1<<unix.NFT_MSG_DELSETELEM, | ||
MonitorObjectRuleset: 1<<unix.NFT_MSG_NEWTABLE | 1<<unix.NFT_MSG_DELTABLE | | ||
1<<unix.NFT_MSG_NEWCHAIN | 1<<unix.NFT_MSG_DELCHAIN | | ||
1<<unix.NFT_MSG_NEWRULE | 1<<unix.NFT_MSG_DELRULE | | ||
1<<unix.NFT_MSG_NEWSET | 1<<unix.NFT_MSG_DELSET | | ||
1<<unix.NFT_MSG_NEWSETELEM | 1<<unix.NFT_MSG_DELSETELEM | | ||
1<<unix.NFT_MSG_NEWOBJ | 1<<unix.NFT_MSG_DELOBJ, | ||
}, | ||
MonitorActionNew: { | ||
MonitorObjectAny: 1<<unix.NFT_MSG_NEWTABLE | | ||
1<<unix.NFT_MSG_NEWCHAIN | | ||
1<<unix.NFT_MSG_NEWRULE | | ||
1<<unix.NFT_MSG_NEWSET | | ||
1<<unix.NFT_MSG_NEWSETELEM, | ||
MonitorObjectTables: 1 << unix.NFT_MSG_NEWTABLE, | ||
MonitorObjectChains: 1 << unix.NFT_MSG_NEWCHAIN, | ||
MonitorObjectRules: 1 << unix.NFT_MSG_NEWRULE, | ||
MonitorObjectSets: 1 << unix.NFT_MSG_NEWSET, | ||
MonitorObjectRuleset: 1<<unix.NFT_MSG_NEWTABLE | | ||
1<<unix.NFT_MSG_NEWCHAIN | | ||
1<<unix.NFT_MSG_NEWRULE | | ||
1<<unix.NFT_MSG_NEWSET | | ||
1<<unix.NFT_MSG_NEWSETELEM | | ||
1<<unix.NFT_MSG_NEWOBJ, | ||
}, | ||
MonitorActionDel: { | ||
MonitorObjectAny: 1<<unix.NFT_MSG_DELTABLE | | ||
1<<unix.NFT_MSG_DELCHAIN | | ||
1<<unix.NFT_MSG_DELRULE | | ||
1<<unix.NFT_MSG_DELSET | | ||
1<<unix.NFT_MSG_DELSETELEM | | ||
1<<unix.NFT_MSG_DELOBJ, | ||
}, | ||
} | ||
monitorFlagsInitOnce sync.Once | ||
) | ||
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type MonitorEventType int | ||
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const ( | ||
MonitorEventTypeNewTable MonitorEventType = unix.NFT_MSG_NEWTABLE | ||
MonitorEventTypeDelTable MonitorEventType = unix.NFT_MSG_DELTABLE | ||
MonitorEventTypeNewChain MonitorEventType = unix.NFT_MSG_NEWCHAIN | ||
MonitorEventTypeDelChain MonitorEventType = unix.NFT_MSG_DELCHAIN | ||
MonitorEventTypeNewRule MonitorEventType = unix.NFT_MSG_NEWRULE | ||
MonitorEventTypeDelRule MonitorEventType = unix.NFT_MSG_DELRULE | ||
MonitorEventTypeNewSet MonitorEventType = unix.NFT_MSG_NEWSET | ||
MonitorEventTypeDelSet MonitorEventType = unix.NFT_MSG_DELSET | ||
MonitorEventTypeNewSetElem MonitorEventType = unix.NFT_MSG_NEWSETELEM | ||
MonitorEventTypeDelSetElem MonitorEventType = unix.NFT_MSG_DELSETELEM | ||
MonitorEventTypeNewObj MonitorEventType = unix.NFT_MSG_NEWOBJ | ||
MonitorEventTypeDelObj MonitorEventType = unix.NFT_MSG_DELOBJ | ||
MonitorEventTypeOOB MonitorEventType = math.MaxInt // out of band event | ||
) | ||
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type MonitorEvent struct { | ||
Type MonitorEventType | ||
Data any | ||
Error error | ||
} | ||
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const ( | ||
monitorOK = iota | ||
monitorClosed | ||
) | ||
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// A Monitor to track actions on objects. | ||
type Monitor struct { | ||
action MonitorAction | ||
object MonitorObject | ||
monitorFlags uint32 | ||
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conn *netlink.Conn | ||
closer netlinkCloser | ||
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// mu covers eventCh and status | ||
mu sync.Mutex | ||
eventCh chan *MonitorEvent | ||
status int | ||
} | ||
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type MonitorOption func(*Monitor) | ||
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func WithMonitorEventBuffer(size int) MonitorOption { | ||
return func(monitor *Monitor) { | ||
monitor.eventCh = make(chan *MonitorEvent, size) | ||
} | ||
} | ||
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// WithMonitorAction to set monitor actions like new, del or any. | ||
func WithMonitorAction(action MonitorAction) MonitorOption { | ||
return func(monitor *Monitor) { | ||
monitor.action = action | ||
} | ||
} | ||
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// WithMonitorObject to set monitor objects. | ||
func WithMonitorObject(object MonitorObject) MonitorOption { | ||
return func(monitor *Monitor) { | ||
monitor.object = object | ||
} | ||
} | ||
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// NewMonitor returns a Monitor with options to be started. | ||
func NewMonitor(opts ...MonitorOption) *Monitor { | ||
monitor := &Monitor{ | ||
status: monitorOK, | ||
} | ||
for _, opt := range opts { | ||
opt(monitor) | ||
} | ||
if monitor.eventCh == nil { | ||
monitor.eventCh = make(chan *MonitorEvent) | ||
} | ||
objects, ok := monitorFlags[monitor.action] | ||
if !ok { | ||
objects = monitorFlags[MonitorActionAny] | ||
} | ||
flags, ok := objects[monitor.object] | ||
if !ok { | ||
flags = objects[MonitorObjectAny] | ||
} | ||
monitor.monitorFlags = flags | ||
return monitor | ||
} | ||
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func (monitor *Monitor) monitor() { | ||
for { | ||
msgs, err := monitor.conn.Receive() | ||
if err != nil { | ||
if strings.Contains(err.Error(), "use of closed file") { | ||
// ignore the error that be closed | ||
break | ||
} else { | ||
// any other errors will be send to user, and then to close eventCh | ||
event := &MonitorEvent{ | ||
Type: MonitorEventTypeOOB, | ||
Data: nil, | ||
Error: err, | ||
} | ||
monitor.eventCh <- event | ||
break | ||
} | ||
} | ||
for _, msg := range msgs { | ||
if msg.Header.Type&0xff00>>8 != netlink.HeaderType(unix.NFNL_SUBSYS_NFTABLES) { | ||
continue | ||
} | ||
msgType := msg.Header.Type & 0x00ff | ||
if monitor.monitorFlags&1<<msgType == 0 { | ||
continue | ||
} | ||
switch msgType { | ||
case unix.NFT_MSG_NEWTABLE, unix.NFT_MSG_DELTABLE: | ||
table, err := tableFromMsg(msg) | ||
event := &MonitorEvent{ | ||
Type: MonitorEventType(msgType), | ||
Data: table, | ||
Error: err, | ||
} | ||
monitor.eventCh <- event | ||
case unix.NFT_MSG_NEWCHAIN, unix.NFT_MSG_DELCHAIN: | ||
chain, err := chainFromMsg(msg) | ||
event := &MonitorEvent{ | ||
Type: MonitorEventType(msgType), | ||
Data: chain, | ||
Error: err, | ||
} | ||
monitor.eventCh <- event | ||
case unix.NFT_MSG_NEWRULE, unix.NFT_MSG_DELRULE: | ||
rule, err := parseRuleFromMsg(msg) | ||
event := &MonitorEvent{ | ||
Type: MonitorEventType(msgType), | ||
Data: rule, | ||
Error: err, | ||
} | ||
monitor.eventCh <- event | ||
case unix.NFT_MSG_NEWSET, unix.NFT_MSG_DELSET: | ||
set, err := setsFromMsg(msg) | ||
event := &MonitorEvent{ | ||
Type: MonitorEventType(msgType), | ||
Data: set, | ||
Error: err, | ||
} | ||
monitor.eventCh <- event | ||
case unix.NFT_MSG_NEWSETELEM, unix.NFT_MSG_DELSETELEM: | ||
elems, err := elementsFromMsg(uint8(TableFamilyUnspecified), msg) | ||
event := &MonitorEvent{ | ||
Type: MonitorEventType(msgType), | ||
Data: elems, | ||
Error: err, | ||
} | ||
monitor.eventCh <- event | ||
case unix.NFT_MSG_NEWOBJ, unix.NFT_MSG_DELOBJ: | ||
obj, err := objFromMsg(msg) | ||
event := &MonitorEvent{ | ||
Type: MonitorEventType(msgType), | ||
Data: obj, | ||
Error: err, | ||
} | ||
monitor.eventCh <- event | ||
} | ||
} | ||
} | ||
monitor.mu.Lock() | ||
defer monitor.mu.Unlock() | ||
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if monitor.status != monitorClosed { | ||
monitor.status = monitorClosed | ||
} | ||
close(monitor.eventCh) | ||
} | ||
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func (monitor *Monitor) Close() error { | ||
monitor.mu.Lock() | ||
defer monitor.mu.Unlock() | ||
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if monitor.status != monitorClosed { | ||
monitor.status = monitorClosed | ||
return monitor.closer() | ||
} | ||
return nil | ||
} | ||
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// AddMonitor to perform the monitor immediately. The channel will be closed after | ||
// calling Close on Monitor or encountering a netlink conn error while Receive. | ||
// Caller may receive a MonitorEventTypeOOB event which contains an error we didn't | ||
// handle, for now. | ||
func (cc *Conn) AddMonitor(monitor *Monitor) (chan *MonitorEvent, error) { | ||
conn, closer, err := cc.netlinkConn() | ||
if err != nil { | ||
return nil, err | ||
} | ||
monitor.conn = conn | ||
monitor.closer = closer | ||
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if monitor.monitorFlags != 0 { | ||
if err = conn.JoinGroup(uint32(unix.NFNLGRP_NFTABLES)); err != nil { | ||
monitor.closer() | ||
return nil, err | ||
} | ||
} | ||
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go monitor.monitor() | ||
return monitor.eventCh, nil | ||
} | ||
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func parseRuleFromMsg(msg netlink.Message) (*Rule, error) { | ||
genmsg := &NFGenMsg{} | ||
genmsg.Decode(msg.Data[:4]) | ||
return ruleFromMsg(TableFamily(genmsg.NFGenFamily), msg) | ||
} |
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