diff --git a/ChangeLog b/ChangeLog
index a0c5991ba9ebc53ccdccd2ff2ee234b27fb20443..0df8124377a2273ef00cefd5c2706e16dacc17eb 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,8 @@ Changes in version 0.0.9 - UNRELEASED:
- Various meek_lite code cleanups and bug fixes.
- Bug 29077: uTLS for ClientHello camouflage (meek_lite).
- More fixes to HTTP Basic auth.
+ - (meek_lite) Pin the certificate chain public keys for the default
+ Tor Browser Azure bridge (meek_lite).
Changes in version 0.0.8 - 2019-01-20:
- Bug 24793: Send the correct authorization HTTP header for basic auth.
diff --git a/transports/meeklite/hpkp_lite.go b/transports/meeklite/hpkp_lite.go
new file mode 100644
index 0000000000000000000000000000000000000000..9e20d65e896e753a3b88d345e198080438c15ebe
--- /dev/null
+++ b/transports/meeklite/hpkp_lite.go
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2019 Yawning Angel <yawning at schwanenlied dot me>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package meeklite
+
+import (
+ "crypto/sha256"
+ "crypto/x509"
+ "encoding/base64"
+
+ "golang.org/x/net/idna"
+)
+
+var builtinPinDB *hpkpDatabase
+
+type hpkpDatabase struct {
+ pins map[string]map[string]bool
+}
+
+func (db *hpkpDatabase) HasPins(host string) (string, bool) {
+ h, err := normalizeHost(host)
+ return h, (db.pins[host] != nil && err == nil)
+}
+
+func (db *hpkpDatabase) Validate(host string, chains [][]*x509.Certificate) bool {
+ var ok bool
+ if host, ok = db.HasPins(host); !ok {
+ return false
+ }
+
+ pins := db.pins[host]
+ for _, chain := range chains {
+ for _, cert := range chain {
+ derivedPin := sha256.Sum256(cert.RawSubjectPublicKeyInfo)
+ derivedPinEncoded := base64.StdEncoding.EncodeToString(derivedPin[:])
+ if !pins[derivedPinEncoded] {
+ return false
+ }
+ }
+ }
+
+ return true
+}
+
+func (db *hpkpDatabase) Add(host string, pins []string) {
+ h, err := normalizeHost(host)
+ if err != nil {
+ panic("failed to add hpkp pin, invalid host: " + err.Error())
+ }
+
+ pinMap := make(map[string]bool)
+ for _, pin := range pins {
+ pinMap[pin] = true
+ }
+
+ db.pins[h] = pinMap
+}
+
+func normalizeHost(host string) (string, error) {
+ return idna.Lookup.ToASCII(host)
+}
+
+func init() {
+ builtinPinDB = &hpkpDatabase{
+ pins: make(map[string]map[string]bool),
+ }
+
+ // Generated on 2019-02-04.
+ builtinPinDB.Add("ajax.aspnetcdn.com", []string{
+ "PPjoAKk+kCVr9VNPXJkyHXEKnIyd5t5NqpPL3zCvJOE=",
+ "wBdPad95AU7OgLRs0FU/E6ILO1MSCM84kJ9y0H+TT7s=",
+ "Y9mvm0exBk1JoQ57f9Vm28jKo5lFm/woKcVxrYxu80o=",
+ })
+}
diff --git a/transports/meeklite/meek.go b/transports/meeklite/meek.go
index f86e9344bdd98819cbaa24c1a8b6bd32d66e602b..fc97d7f22df52b440dd77b212802e87b10161958 100644
--- a/transports/meeklite/meek.go
+++ b/transports/meeklite/meek.go
@@ -41,6 +41,7 @@ import (
gourl "net/url"
"os"
"runtime"
+ "strings"
"sync"
"time"
@@ -50,9 +51,10 @@ import (
)
const (
- urlArg = "url"
- frontArg = "front"
- utlsArg = "utls"
+ urlArg = "url"
+ frontArg = "front"
+ utlsArg = "utls"
+ disableHPKPArg = "disableHPKP"
maxChanBacklog = 16
@@ -76,7 +78,8 @@ type meekClientArgs struct {
url *gourl.URL
front string
- utls *utls.ClientHelloID
+ utls *utls.ClientHelloID
+ disableHPKP bool
}
func (ca *meekClientArgs) Network() string {
@@ -114,6 +117,12 @@ func newClientArgs(args *pt.Args) (ca *meekClientArgs, err error) {
return nil, err
}
+ // Parse the (optional) HPKP disable argument.
+ hpkpOpt, _ := args.Get(disableHPKPArg)
+ if strings.ToLower(hpkpOpt) == "true" {
+ ca.disableHPKP = true
+ }
+
return ca, nil
}
@@ -358,7 +367,7 @@ func newMeekConn(network, addr string, dialFn base.DialFunc, ca *meekClientArgs)
case nil:
rt = &http.Transport{Dial: dialFn}
default:
- rt = newRoundTripper(dialFn, ca.utls)
+ rt = newRoundTripper(dialFn, ca.utls, ca.disableHPKP)
}
conn := &meekConn{
diff --git a/transports/meeklite/transport.go b/transports/meeklite/transport.go
index 2736fe10e3896d013f51c16c8a8aeb5bbc93dcc7..5817be0e7e87d45ef6d60790b6c619af3db26f4a 100644
--- a/transports/meeklite/transport.go
+++ b/transports/meeklite/transport.go
@@ -19,6 +19,7 @@ package meeklite
import (
"crypto/tls"
+ "crypto/x509"
"errors"
"fmt"
"net"
@@ -28,6 +29,7 @@ import (
"strings"
"sync"
+ "gitlab.com/yawning/obfs4.git/common/log"
"gitlab.com/yawning/obfs4.git/transports/base"
utls "gitlab.com/yawning/utls.git"
"golang.org/x/net/http2"
@@ -64,7 +66,8 @@ type roundTripper struct {
dialFn base.DialFunc
transport http.RoundTripper
- initConn net.Conn
+ initConn net.Conn
+ disableHPKP bool
}
func (rt *roundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
@@ -128,7 +131,25 @@ func (rt *roundTripper) dialTLS(network, addr string) (net.Conn, error) {
host = addr
}
- conn := utls.UClient(rawConn, &utls.Config{ServerName: host}, *rt.clientHelloID)
+ var verifyPeerCertificateFn func([][]byte, [][]*x509.Certificate) error
+ if !rt.disableHPKP {
+ if pinHost, ok := builtinPinDB.HasPins(host); ok {
+ if rt.transport == nil {
+ log.Debugf("meek_lite - HPKP enabled for host: %v", pinHost)
+ }
+ verifyPeerCertificateFn = func(rawCerts [][]byte, verifiedChains [][]*x509.Certificate) error {
+ if !builtinPinDB.Validate(pinHost, verifiedChains) {
+ log.Errorf("meek_lite - HPKP validation failure, potential MITM for host: %v", pinHost)
+ return fmt.Errorf("meek_lite: HPKP validation failure for host: %v", pinHost)
+ }
+ return nil
+ }
+ }
+ } else if rt.transport == nil {
+ log.Warnf("meek_lite - HPKP disabled for host: %v", host)
+ }
+
+ conn := utls.UClient(rawConn, &utls.Config{ServerName: host, VerifyPeerCertificate: verifyPeerCertificateFn}, *rt.clientHelloID)
if err = conn.Handshake(); err != nil {
conn.Close()
return nil, err
@@ -170,10 +191,11 @@ func getDialTLSAddr(u *url.URL) string {
return net.JoinHostPort(u.Host, strconv.Itoa(pInt))
}
-func newRoundTripper(dialFn base.DialFunc, clientHelloID *utls.ClientHelloID) http.RoundTripper {
+func newRoundTripper(dialFn base.DialFunc, clientHelloID *utls.ClientHelloID, disableHPKP bool) http.RoundTripper {
return &roundTripper{
clientHelloID: clientHelloID,
dialFn: dialFn,
+ disableHPKP: disableHPKP,
}
}