mirror of https://github.com/k3s-io/k3s
193 lines
5.4 KiB
Go
193 lines
5.4 KiB
Go
// Copyright 2017 Google Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tcpproxy
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import (
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"bufio"
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"bytes"
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"context"
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"crypto/tls"
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"io"
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"net"
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"strings"
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)
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// AddSNIRoute appends a route to the ipPort listener that routes to
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// dest if the incoming TLS SNI server name is sni. If it doesn't
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// match, rule processing continues for any additional routes on
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// ipPort.
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//
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// By default, the proxy will route all ACME tls-sni-01 challenges
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// received on ipPort to all SNI dests. You can disable ACME routing
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// with AddStopACMESearch.
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//
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// The ipPort is any valid net.Listen TCP address.
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func (p *Proxy) AddSNIRoute(ipPort, sni string, dest Target) {
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p.AddSNIMatchRoute(ipPort, equals(sni), dest)
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}
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// AddSNIMatchRoute appends a route to the ipPort listener that routes
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// to dest if the incoming TLS SNI server name is accepted by
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// matcher. If it doesn't match, rule processing continues for any
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// additional routes on ipPort.
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//
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// By default, the proxy will route all ACME tls-sni-01 challenges
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// received on ipPort to all SNI dests. You can disable ACME routing
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// with AddStopACMESearch.
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//
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// The ipPort is any valid net.Listen TCP address.
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func (p *Proxy) AddSNIMatchRoute(ipPort string, matcher Matcher, dest Target) {
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cfg := p.configFor(ipPort)
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if !cfg.stopACME {
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if len(cfg.acmeTargets) == 0 {
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p.addRoute(ipPort, &acmeMatch{cfg})
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}
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cfg.acmeTargets = append(cfg.acmeTargets, dest)
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}
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p.addRoute(ipPort, sniMatch{matcher, dest})
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}
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// AddStopACMESearch prevents ACME probing of subsequent SNI routes.
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// Any ACME challenges on ipPort for SNI routes previously added
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// before this call will still be proxied to all possible SNI
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// backends.
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func (p *Proxy) AddStopACMESearch(ipPort string) {
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p.configFor(ipPort).stopACME = true
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}
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type sniMatch struct {
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matcher Matcher
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target Target
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}
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func (m sniMatch) match(br *bufio.Reader) (Target, string) {
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sni := clientHelloServerName(br)
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if m.matcher(context.TODO(), sni) {
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return m.target, sni
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}
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return nil, ""
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}
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// acmeMatch matches "*.acme.invalid" ACME tls-sni-01 challenges and
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// searches for a Target in cfg.acmeTargets that has the challenge
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// response.
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type acmeMatch struct {
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cfg *config
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}
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func (m *acmeMatch) match(br *bufio.Reader) (Target, string) {
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sni := clientHelloServerName(br)
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if !strings.HasSuffix(sni, ".acme.invalid") {
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return nil, ""
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}
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// TODO: cache. ACME issuers will hit multiple times in a short
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// burst for each issuance event. A short TTL cache + singleflight
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// should have an excellent hit rate.
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// TODO: maybe an acme-specific timeout as well?
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// TODO: plumb context upwards?
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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ch := make(chan Target, len(m.cfg.acmeTargets))
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for _, target := range m.cfg.acmeTargets {
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go tryACME(ctx, ch, target, sni)
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}
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for range m.cfg.acmeTargets {
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if target := <-ch; target != nil {
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return target, sni
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}
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}
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// No target was happy with the provided challenge.
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return nil, ""
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}
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func tryACME(ctx context.Context, ch chan<- Target, dest Target, sni string) {
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var ret Target
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defer func() { ch <- ret }()
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conn, targetConn := net.Pipe()
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defer conn.Close()
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go dest.HandleConn(targetConn)
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deadline, ok := ctx.Deadline()
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if ok {
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conn.SetDeadline(deadline)
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}
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client := tls.Client(conn, &tls.Config{
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ServerName: sni,
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InsecureSkipVerify: true,
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})
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if err := client.Handshake(); err != nil {
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// TODO: log?
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return
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}
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certs := client.ConnectionState().PeerCertificates
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if len(certs) == 0 {
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// TODO: log?
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return
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}
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// acme says the first cert offered by the server must match the
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// challenge hostname.
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if err := certs[0].VerifyHostname(sni); err != nil {
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// TODO: log?
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return
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}
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// Target presented what looks like a valid challenge
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// response, send it back to the matcher.
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ret = dest
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}
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// clientHelloServerName returns the SNI server name inside the TLS ClientHello,
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// without consuming any bytes from br.
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// On any error, the empty string is returned.
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func clientHelloServerName(br *bufio.Reader) (sni string) {
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const recordHeaderLen = 5
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hdr, err := br.Peek(recordHeaderLen)
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if err != nil {
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return ""
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}
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const recordTypeHandshake = 0x16
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if hdr[0] != recordTypeHandshake {
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return "" // Not TLS.
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}
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recLen := int(hdr[3])<<8 | int(hdr[4]) // ignoring version in hdr[1:3]
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helloBytes, err := br.Peek(recordHeaderLen + recLen)
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if err != nil {
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return ""
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}
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tls.Server(sniSniffConn{r: bytes.NewReader(helloBytes)}, &tls.Config{
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GetConfigForClient: func(hello *tls.ClientHelloInfo) (*tls.Config, error) {
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sni = hello.ServerName
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return nil, nil
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},
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}).Handshake()
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return
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}
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// sniSniffConn is a net.Conn that reads from r, fails on Writes,
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// and crashes otherwise.
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type sniSniffConn struct {
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r io.Reader
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net.Conn // nil; crash on any unexpected use
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}
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func (c sniSniffConn) Read(p []byte) (int, error) { return c.r.Read(p) }
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func (sniSniffConn) Write(p []byte) (int, error) { return 0, io.EOF }
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