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Fix dnsonly nameserver

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This commit is contained in:
Daniel 2019-05-10 12:10:09 +02:00
parent e37f706223
commit 79c62036f3
1 changed files with 97 additions and 25 deletions
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122
nameserver/only/nameserver.go
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@ -1,6 +1,7 @@
package only
import (
"context"
"net"
"time"
@ -12,10 +13,33 @@ import (
"github.com/Safing/portmaster/analytics/algs"
"github.com/Safing/portmaster/intel"
"github.com/Safing/portmaster/network/netutils"
"github.com/Safing/portmaster/status"
)
var (
localhostIPs []dns.RR
)
func init() {
modules.Register("nameserver", nil, start, nil, "intel")
modules.Register("nameserver", prep, start, nil, "intel")
}
func prep() error {
intel.SetLocalAddrFactory(func(network string) net.Addr { return nil })
localhostIPv4, err := dns.NewRR("localhost. 17 IN A 127.0.0.1")
if err != nil {
return err
}
localhostIPv6, err := dns.NewRR("localhost. 17 IN AAAA ::1")
if err != nil {
return err
}
localhostIPs = []dns.RR{localhostIPv4, localhostIPv6}
return nil
}
func start() error {
@ -44,62 +68,110 @@ func nxDomain(w dns.ResponseWriter, query *dns.Msg) {
func handleRequest(w dns.ResponseWriter, query *dns.Msg) {
// TODO: if there are 3 request for the same domain/type in a row, delete all caches of that domain
// TODO: handle securityLevelOff
// only process first question, that's how everyone does it.
question := query.Question[0]
fqdn := dns.Fqdn(question.Name)
qtype := dns.Type(question.Qtype)
// debug log
rAddr, ok := w.RemoteAddr().(*net.UDPAddr)
if !ok {
log.Warningf("nameserver: could not get address of request, returning nxdomain")
// check class
if question.Qclass != dns.ClassINET {
// we only serve IN records, return nxdomain
nxDomain(w, query)
return
}
// log.Tracef("nameserver: got request for %s%s from %s:%d", fqdn, qtype, rAddr.IP, uint16(rAddr.Port))
// use this to time how long it takes process this request
// timed := time.Now()
// defer log.Tracef("nameserver: took %s to handle request for %s%s", time.Now().Sub(timed).String(), fqdn, qtype.String())
// handle request for localhost
if fqdn == "localhost." {
m := new(dns.Msg)
m.SetReply(query)
m.Answer = localhostIPs
w.WriteMsg(m)
}
// get addresses
remoteAddr, ok := w.RemoteAddr().(*net.UDPAddr)
if !ok {
log.Warningf("nameserver: could not get remote address of request for %s%s, ignoring", fqdn, qtype)
return
}
localAddr, ok := w.RemoteAddr().(*net.UDPAddr)
if !ok {
log.Warningf("nameserver: could not get local address of request for %s%s, ignoring", fqdn, qtype)
return
}
// ignore external request
if !remoteAddr.IP.Equal(localAddr.IP) {
log.Warningf("nameserver: external request for %s%s, ignoring", fqdn, qtype)
return
}
// check if valid domain name
if !netutils.IsValidFqdn(fqdn) {
log.Tracef("nameserver: domain name %s is invalid, returning nxdomain", fqdn)
log.Debugf("nameserver: domain name %s is invalid, returning nxdomain", fqdn)
nxDomain(w, query)
return
}
// start tracer
ctx := log.AddTracer(context.Background())
log.Tracer(ctx).Tracef("nameserver: handling new request for %s%s from %s:%d", fqdn, qtype, remoteAddr.IP, remoteAddr.Port)
// TODO: if there are 3 request for the same domain/type in a row, delete all caches of that domain
// check for possible DNS tunneling / data transmission
// TODO: improve this
lms := algs.LmsScoreOfDomain(fqdn)
log.Tracef("nameserver: domain %s has lms score of %f", fqdn, lms)
// log.Tracef("nameserver: domain %s has lms score of %f", fqdn, lms)
if lms < 10 {
log.Tracef("nameserver: possible data tunnel: %s has lms score of %f, returning nxdomain", fqdn, lms)
nxDomain(w, query)
return
}
// check class
if question.Qclass != dns.ClassINET {
// we only serve IN records, send NXDOMAIN
log.WarningTracef(ctx, "nameserver: possible data tunnel by %s:%d: %s has lms score of %f, returning nxdomain", remoteAddr.IP, remoteAddr.Port, fqdn, lms)
nxDomain(w, query)
return
}
// get intel and RRs
// start = time.Now()
_, rrCache := intel.GetIntelAndRRs(fqdn, qtype, 0)
_, rrCache := intel.GetIntelAndRRs(ctx, fqdn, qtype, status.SecurityLevelDynamic)
// log.Tracef("nameserver: took %s to get intel and RRs", time.Since(start))
if rrCache == nil {
// TODO: analyze nxdomain requests, malware could be trying DGA-domains
log.Infof("nameserver: %s%s is nxdomain", fqdn, qtype)
log.WarningTracef(ctx, "nameserver: %s:%d requested %s%s, is nxdomain", remoteAddr.IP, remoteAddr.Port, fqdn, qtype)
nxDomain(w, query)
return
}
// save IP addresses to IPInfo
for _, rr := range append(rrCache.Answer, rrCache.Extra...) {
switch v := rr.(type) {
case *dns.A:
ipInfo, err := intel.GetIPInfo(v.A.String())
if err != nil {
ipInfo = &intel.IPInfo{
IP: v.A.String(),
Domains: []string{fqdn},
}
ipInfo.Save()
} else {
if ipInfo.AddDomain(fqdn) {
ipInfo.Save()
}
}
case *dns.AAAA:
ipInfo, err := intel.GetIPInfo(v.AAAA.String())
if err != nil {
ipInfo = &intel.IPInfo{
IP: v.AAAA.String(),
Domains: []string{fqdn},
}
ipInfo.Save()
} else {
if ipInfo.AddDomain(fqdn) {
ipInfo.Save()
}
}
}
}
// reply to query
m := new(dns.Msg)
m.SetReply(query)
@ -107,5 +179,5 @@ func handleRequest(w dns.ResponseWriter, query *dns.Msg) {
m.Ns = rrCache.Ns
m.Extra = rrCache.Extra
w.WriteMsg(m)
log.Tracef("nameserver: replied to request for %s%s from %s:%d", fqdn, qtype, rAddr.IP, uint16(rAddr.Port))
log.DebugTracef(ctx, "nameserver: returning response %s%s to %s:%d", fqdn, qtype, remoteAddr.IP, remoteAddr.Port)
}