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Pull request: 4927-ddr-ip-san 

Merge in DNS/adguard-home from 4927-ddr-ip-san to master

Updates #4927.

Squashed commit of the following:

commit 92e7498a7a9101648c4cfdf719adf4eb135fc903
Merge: f4770abf fa0fd90d
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Nov 2 14:29:08 2022 +0300

    Merge branch 'master' into 4927-ddr-ip-san

commit f4770abf98ea2c0db2f0c2ddb9509a29a06c9509
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Wed Nov 2 13:50:40 2022 +0300

    dnsforward: imp logs

commit 8d71371365070e221e104ae20acc8312e840eff9
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Nov 1 20:57:43 2022 +0300

    all: imp code, docs

commit 9793820f2c581e0ffcb28a59677be5c8df0c43f3
Author: Eugene Burkov <E.Burkov@AdGuard.COM>
Date:   Tue Nov 1 19:37:39 2022 +0300

    all: remember the cert props
This commit is contained in:
Eugene Burkov 2022-11-02 14:37:41 +03:00
parent fa0fd90ddd
commit c139287787
6 changed files with 82 additions and 68 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
CHANGELOG.md
View File

@ -39,6 +39,8 @@ and this project adheres to
### Changed
- DNS-over-TLS resolvers aren't returned anymore when the configured TLS
certificate contains no IP addresses ([#4927]).
- Responses with `SERVFAIL` code are now cached for at least 30 seconds.
### Deprecated
@ -63,6 +65,7 @@ and this project adheres to
[#4898]: https://github.com/AdguardTeam/AdGuardHome/issues/4898
[#4916]: https://github.com/AdguardTeam/AdGuardHome/issues/4916
[#4925]: https://github.com/AdguardTeam/AdGuardHome/issues/4925
[#4927]: https://github.com/AdguardTeam/AdGuardHome/issues/4927
[#4942]: https://github.com/AdguardTeam/AdGuardHome/issues/4942
[#4986]: https://github.com/AdguardTeam/AdGuardHome/issues/4986
[#4990]: https://github.com/AdguardTeam/AdGuardHome/issues/4990

18
internal/aghtls/aghtls.go
View File

@ -3,7 +3,9 @@ package aghtls
import (
"crypto/tls"
"crypto/x509"
"fmt"
"net/netip"
"github.com/AdguardTeam/golibs/log"
)
@ -69,3 +71,19 @@ func SaferCipherSuites() (safe []uint16) {
return safe
}
// CertificateHasIP returns true if cert has at least a single IP address among
// its subjectAltNames.
func CertificateHasIP(cert *x509.Certificate) (ok bool) {
if len(cert.IPAddresses) > 0 {
return true
}
for _, name := range cert.DNSNames {
if _, err := netip.ParseAddr(name); err == nil {
return true
}
}
return false
}

36
internal/dnsforward/config.go
View File

@ -12,6 +12,7 @@ import (
"github.com/AdguardTeam/AdGuardHome/internal/aghalg"
"github.com/AdguardTeam/AdGuardHome/internal/aghhttp"
"github.com/AdguardTeam/AdGuardHome/internal/aghtls"
"github.com/AdguardTeam/AdGuardHome/internal/filtering"
"github.com/AdguardTeam/dnsproxy/proxy"
"github.com/AdguardTeam/dnsproxy/upstream"
@ -146,13 +147,12 @@ type FilteringConfig struct {
// TLSConfig is the TLS configuration for HTTPS, DNS-over-HTTPS, and DNS-over-TLS
type TLSConfig struct {
cert tls.Certificate
TLSListenAddrs []*net.TCPAddr `yaml:"-" json:"-"`
QUICListenAddrs []*net.UDPAddr `yaml:"-" json:"-"`
HTTPSListenAddrs []*net.TCPAddr `yaml:"-" json:"-"`
// Reject connection if the client uses server name (in SNI) that doesn't match the certificate
StrictSNICheck bool `yaml:"strict_sni_check" json:"-"`
// PEM-encoded certificates chain
CertificateChain string `yaml:"certificate_chain" json:"certificate_chain"`
// PEM-encoded private key
@ -168,13 +168,20 @@ type TLSConfig struct {
// used for ClientID checking and Discovery of Designated Resolvers (DDR).
ServerName string `yaml:"-" json:"-"`
cert tls.Certificate
// DNS names from certificate (SAN) or CN value from Subject
dnsNames []string
// OverrideTLSCiphers, when set, contains the names of the cipher suites to
// use. If the slice is empty, the default safe suites are used.
OverrideTLSCiphers []string `yaml:"override_tls_ciphers,omitempty" json:"-"`
// StrictSNICheck controls if the connections with SNI mismatching the
// certificate's ones should be rejected.
StrictSNICheck bool `yaml:"strict_sni_check" json:"-"`
// hasIPAddrs is set during the certificate parsing and is true if the
// configured certificate contains at least a single IP address.
hasIPAddrs bool
}
// DNSCryptConfig is the DNSCrypt server configuration struct.
@ -459,7 +466,7 @@ func (s *Server) prepareIpsetListSettings() (err error) {
}
// prepareTLS - prepares TLS configuration for the DNS proxy
func (s *Server) prepareTLS(proxyConfig *proxy.Config) error {
func (s *Server) prepareTLS(proxyConfig *proxy.Config) (err error) {
if len(s.conf.CertificateChainData) == 0 || len(s.conf.PrivateKeyData) == 0 {
return nil
}
@ -478,25 +485,26 @@ func (s *Server) prepareTLS(proxyConfig *proxy.Config) error {
proxyConfig.QUICListenAddr,
)
var err error
s.conf.cert, err = tls.X509KeyPair(s.conf.CertificateChainData, s.conf.PrivateKeyData)
if err != nil {
return fmt.Errorf("failed to parse TLS keypair: %w", err)
}
if s.conf.StrictSNICheck {
var x *x509.Certificate
x, err = x509.ParseCertificate(s.conf.cert.Certificate[0])
cert, err := x509.ParseCertificate(s.conf.cert.Certificate[0])
if err != nil {
return fmt.Errorf("x509.ParseCertificate(): %w", err)
}
if len(x.DNSNames) != 0 {
s.conf.dnsNames = x.DNSNames
log.Debug("dns: using DNS names from certificate's SAN: %v", x.DNSNames)
s.conf.hasIPAddrs = aghtls.CertificateHasIP(cert)
if s.conf.StrictSNICheck {
if len(cert.DNSNames) != 0 {
s.conf.dnsNames = cert.DNSNames
log.Debug("dnsforward: using certificate's SAN as DNS names: %v", cert.DNSNames)
sort.Strings(s.conf.dnsNames)
} else {
s.conf.dnsNames = append(s.conf.dnsNames, x.Subject.CommonName)
log.Debug("dns: using DNS name from certificate's CN: %s", x.Subject.CommonName)
s.conf.dnsNames = append(s.conf.dnsNames, cert.Subject.CommonName)
log.Debug("dnsforward: using certificate's CN as DNS name: %s", cert.Subject.CommonName)
}
}

22
internal/dnsforward/dns.go
View File

@ -259,21 +259,13 @@ func (s *Server) onDHCPLeaseChanged(flags int) {
//
// See https://www.ietf.org/archive/id/draft-ietf-add-ddr-10.html.
func (s *Server) processDDRQuery(dctx *dnsContext) (rc resultCode) {
pctx := dctx.proxyCtx
q := pctx.Req.Question[0]
if !s.conf.HandleDDR {
return resultCodeSuccess
}
pctx := dctx.proxyCtx
q := pctx.Req.Question[0]
if q.Name == ddrHostFQDN {
if s.dnsProxy.TLSListenAddr == nil && s.conf.HTTPSListenAddrs == nil &&
s.dnsProxy.QUICListenAddr == nil || q.Qtype != dns.TypeSVCB {
pctx.Res = s.makeResponse(pctx.Req)
return resultCodeFinish
}
pctx.Res = s.makeDDRResponse(pctx.Req)
return resultCodeFinish
@ -291,6 +283,10 @@ func (s *Server) processDDRQuery(dctx *dnsContext) (rc resultCode) {
// [draft standard]: https://www.ietf.org/archive/id/draft-ietf-add-ddr-10.html.
func (s *Server) makeDDRResponse(req *dns.Msg) (resp *dns.Msg) {
resp = s.makeResponse(req)
if req.Question[0].Qtype != dns.TypeSVCB {
return resp
}
// TODO(e.burkov): Think about storing the FQDN version of the server's
// name somewhere.
domainName := dns.Fqdn(s.conf.ServerName)
@ -312,6 +308,11 @@ func (s *Server) makeDDRResponse(req *dns.Msg) (resp *dns.Msg) {
resp.Answer = append(resp.Answer, ans)
}
if s.conf.hasIPAddrs {
// Only add DNS-over-TLS resolvers in case the certificate contains IP
// addresses.
//
// See https://github.com/AdguardTeam/AdGuardHome/issues/4927.
for _, addr := range s.dnsProxy.TLSListenAddr {
values := []dns.SVCBKeyValue{
&dns.SVCBAlpn{Alpn: []string{"dot"}},
@ -327,6 +328,7 @@ func (s *Server) makeDDRResponse(req *dns.Msg) (resp *dns.Msg) {
resp.Answer = append(resp.Answer, ans)
}
}
for _, addr := range s.dnsProxy.QUICListenAddr {
values := []dns.SVCBKeyValue{

23
internal/dnsforward/dns_test.go
View File

@ -157,19 +157,9 @@ func TestServer_ProcessDDRQuery(t *testing.T) {
func prepareTestServer(t *testing.T, portDoH, portDoT, portDoQ int, ddrEnabled bool) (s *Server) {
t.Helper()
proxyConf := proxy.Config{}
if portDoT > 0 {
proxyConf.TLSListenAddr = []*net.TCPAddr{{Port: portDoT}}
}
if portDoQ > 0 {
proxyConf.QUICListenAddr = []*net.UDPAddr{{Port: portDoQ}}
}
s = &Server{
dnsProxy: &proxy.Proxy{
Config: proxyConf,
Config: proxy.Config{},
},
conf: ServerConfig{
FilteringConfig: FilteringConfig{
@ -181,8 +171,17 @@ func prepareTestServer(t *testing.T, portDoH, portDoT, portDoQ int, ddrEnabled b
},
}
if portDoT > 0 {
s.dnsProxy.TLSListenAddr = []*net.TCPAddr{{Port: portDoT}}
s.conf.hasIPAddrs = true
}
if portDoQ > 0 {
s.dnsProxy.QUICListenAddr = []*net.UDPAddr{{Port: portDoQ}}
}
if portDoH > 0 {
s.conf.TLSConfig.HTTPSListenAddrs = []*net.TCPAddr{{Port: portDoH}}
s.conf.HTTPSListenAddrs = []*net.TCPAddr{{Port: portDoH}}
}
return s

20
internal/home/tls.go
View File

@ -13,7 +13,6 @@ import (
"encoding/pem"
"fmt"
"net/http"
"net/netip"
"os"
"strings"
"sync"
@ -21,6 +20,7 @@ import (
"github.com/AdguardTeam/AdGuardHome/internal/aghalg"
"github.com/AdguardTeam/AdGuardHome/internal/aghhttp"
"github.com/AdguardTeam/AdGuardHome/internal/aghtls"
"github.com/AdguardTeam/AdGuardHome/internal/dnsforward"
"github.com/AdguardTeam/golibs/errors"
"github.com/AdguardTeam/golibs/log"
@ -513,22 +513,6 @@ func validateCertChain(certs []*x509.Certificate, srvName string) (err error) {
return nil
}
// certHasIP returns true if cert has at least a single IP address either in its
// DNS names or in the IP addresses section.
func certHasIP(cert *x509.Certificate) (ok bool) {
if len(cert.IPAddresses) > 0 {
return true
}
for _, name := range cert.DNSNames {
if _, err := netip.ParseAddr(name); err == nil {
return true
}
}
return false
}
// parseCertChain parses the certificate chain from raw data, and returns it.
// If ok is true, the returned error, if any, is not critical.
func parseCertChain(chain []byte) (parsedCerts []*x509.Certificate, ok bool, err error) {
@ -550,7 +534,7 @@ func parseCertChain(chain []byte) (parsedCerts []*x509.Certificate, ok bool, err
log.Info("tls: number of certs: %d", len(parsedCerts))
if !certHasIP(parsedCerts[0]) {
if !aghtls.CertificateHasIP(parsedCerts[0]) {
err = errors.Error(`certificate has no IP addresses` +
`, this may cause issues with DNS-over-TLS clients`)
}