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nflog.go
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nflog.go
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// Copyright Istio Authors
//
// 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.
package log
import (
"context"
"net"
"github.com/florianl/go-nflog/v2"
"golang.org/x/net/ipv4"
"istio.io/istio/pkg/env"
"istio.io/istio/pkg/log"
)
var TraceLoggingEnabled = env.Register(
"IPTABLES_TRACE_LOGGING",
false,
"When enable, all iptables actions will be logged. "+
"This requires NET_ADMIN privilege and has noisy logs; as a result, this is intended for debugging only").Get()
var iptablesTrace = log.RegisterScope("iptables", "trace logs for iptables")
// ReadNFLOGSocket reads from the nflog socket, sending output to logs.
// This is intended for debugging only.
func ReadNFLOGSocket(ctx context.Context) {
if !TraceLoggingEnabled {
return
}
iptablesTrace.Infof("starting nftable log")
// We expect to read logs from rules like:
// `-j NFLOG --nflog-group 1337`
config := nflog.Config{
Group: 1337,
Copymode: nflog.CopyPacket,
Logger: iptablesTrace,
}
nf, err := nflog.Open(&config)
if err != nil {
log.Errorf("could not open nflog socket: %v", err)
return
}
defer nf.Close()
fn := func(attrs nflog.Attribute) int {
src, dst := "", ""
if attrs.Payload != nil {
v4, err := ipv4.ParseHeader(*attrs.Payload)
if err == nil {
src = v4.Src.String()
dst = v4.Dst.String()
}
}
prefix := ""
if attrs.Prefix != nil {
prefix = *attrs.Prefix
}
comment := IDToCommand[prefix].Comment
uid, gid := uint32(0), uint32(0)
if attrs.UID != nil {
uid = *attrs.UID
}
if attrs.GID != nil {
gid = *attrs.GID
}
inDev, outDev := "", ""
if attrs.InDev != nil {
ii, err := net.InterfaceByIndex(int(*attrs.InDev))
if err == nil {
inDev = ii.Name
}
}
if attrs.OutDev != nil {
ii, err := net.InterfaceByIndex(int(*attrs.OutDev))
if err == nil {
outDev = ii.Name
}
}
iptablesTrace.WithLabels(
"command", prefix,
"uid", uid,
"gid", gid,
"inDev", inDev,
"outDev", outDev,
"src", src,
"dst", dst,
).Infof(comment)
return 0
}
// Register our callback for the nflog
err = nf.RegisterWithErrorFunc(ctx, fn, func(e error) int {
iptablesTrace.Warnf("log failed: %v", e)
return 0
})
if err != nil {
log.Errorf("failed to register nflog callback: %v", err)
return
}
// Block util the context expires
<-ctx.Done()
}