Scott Baker | 2c1c482 | 2019-10-16 11:02:41 -0700 | [diff] [blame^] | 1 | // Copyright 2019 The etcd Authors |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | // Package credentials implements gRPC credential interface with etcd specific logic. |
| 16 | // e.g., client handshake with custom authority parameter |
| 17 | package credentials |
| 18 | |
| 19 | import ( |
| 20 | "context" |
| 21 | "crypto/tls" |
| 22 | "net" |
| 23 | "sync" |
| 24 | |
| 25 | "go.etcd.io/etcd/etcdserver/api/v3rpc/rpctypes" |
| 26 | grpccredentials "google.golang.org/grpc/credentials" |
| 27 | ) |
| 28 | |
| 29 | // Config defines gRPC credential configuration. |
| 30 | type Config struct { |
| 31 | TLSConfig *tls.Config |
| 32 | } |
| 33 | |
| 34 | // Bundle defines gRPC credential interface. |
| 35 | type Bundle interface { |
| 36 | grpccredentials.Bundle |
| 37 | UpdateAuthToken(token string) |
| 38 | } |
| 39 | |
| 40 | // NewBundle constructs a new gRPC credential bundle. |
| 41 | func NewBundle(cfg Config) Bundle { |
| 42 | return &bundle{ |
| 43 | tc: newTransportCredential(cfg.TLSConfig), |
| 44 | rc: newPerRPCCredential(), |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | // bundle implements "grpccredentials.Bundle" interface. |
| 49 | type bundle struct { |
| 50 | tc *transportCredential |
| 51 | rc *perRPCCredential |
| 52 | } |
| 53 | |
| 54 | func (b *bundle) TransportCredentials() grpccredentials.TransportCredentials { |
| 55 | return b.tc |
| 56 | } |
| 57 | |
| 58 | func (b *bundle) PerRPCCredentials() grpccredentials.PerRPCCredentials { |
| 59 | return b.rc |
| 60 | } |
| 61 | |
| 62 | func (b *bundle) NewWithMode(mode string) (grpccredentials.Bundle, error) { |
| 63 | // no-op |
| 64 | return nil, nil |
| 65 | } |
| 66 | |
| 67 | // transportCredential implements "grpccredentials.TransportCredentials" interface. |
| 68 | type transportCredential struct { |
| 69 | gtc grpccredentials.TransportCredentials |
| 70 | } |
| 71 | |
| 72 | func newTransportCredential(cfg *tls.Config) *transportCredential { |
| 73 | return &transportCredential{ |
| 74 | gtc: grpccredentials.NewTLS(cfg), |
| 75 | } |
| 76 | } |
| 77 | |
| 78 | func (tc *transportCredential) ClientHandshake(ctx context.Context, authority string, rawConn net.Conn) (net.Conn, grpccredentials.AuthInfo, error) { |
| 79 | // Only overwrite when authority is an IP address! |
| 80 | // Let's say, a server runs SRV records on "etcd.local" that resolves |
| 81 | // to "m1.etcd.local", and its SAN field also includes "m1.etcd.local". |
| 82 | // But what if SAN does not include its resolved IP address (e.g. 127.0.0.1)? |
| 83 | // Then, the server should only authenticate using its DNS hostname "m1.etcd.local", |
| 84 | // instead of overwriting it with its IP address. |
| 85 | // And we do not overwrite "localhost" either. Only overwrite IP addresses! |
| 86 | if isIP(authority) { |
| 87 | target := rawConn.RemoteAddr().String() |
| 88 | if authority != target { |
| 89 | // When user dials with "grpc.WithDialer", "grpc.DialContext" "cc.parsedTarget" |
| 90 | // update only happens once. This is problematic, because when TLS is enabled, |
| 91 | // retries happen through "grpc.WithDialer" with static "cc.parsedTarget" from |
| 92 | // the initial dial call. |
| 93 | // If the server authenticates by IP addresses, we want to set a new endpoint as |
| 94 | // a new authority. Otherwise |
| 95 | // "transport: authentication handshake failed: x509: certificate is valid for 127.0.0.1, 192.168.121.180, not 192.168.223.156" |
| 96 | // when the new dial target is "192.168.121.180" whose certificate host name is also "192.168.121.180" |
| 97 | // but client tries to authenticate with previously set "cc.parsedTarget" field "192.168.223.156" |
| 98 | authority = target |
| 99 | } |
| 100 | } |
| 101 | return tc.gtc.ClientHandshake(ctx, authority, rawConn) |
| 102 | } |
| 103 | |
| 104 | // return true if given string is an IP. |
| 105 | func isIP(ep string) bool { |
| 106 | return net.ParseIP(ep) != nil |
| 107 | } |
| 108 | |
| 109 | func (tc *transportCredential) ServerHandshake(rawConn net.Conn) (net.Conn, grpccredentials.AuthInfo, error) { |
| 110 | return tc.gtc.ServerHandshake(rawConn) |
| 111 | } |
| 112 | |
| 113 | func (tc *transportCredential) Info() grpccredentials.ProtocolInfo { |
| 114 | return tc.gtc.Info() |
| 115 | } |
| 116 | |
| 117 | func (tc *transportCredential) Clone() grpccredentials.TransportCredentials { |
| 118 | return &transportCredential{ |
| 119 | gtc: tc.gtc.Clone(), |
| 120 | } |
| 121 | } |
| 122 | |
| 123 | func (tc *transportCredential) OverrideServerName(serverNameOverride string) error { |
| 124 | return tc.gtc.OverrideServerName(serverNameOverride) |
| 125 | } |
| 126 | |
| 127 | // perRPCCredential implements "grpccredentials.PerRPCCredentials" interface. |
| 128 | type perRPCCredential struct { |
| 129 | authToken string |
| 130 | authTokenMu sync.RWMutex |
| 131 | } |
| 132 | |
| 133 | func newPerRPCCredential() *perRPCCredential { return &perRPCCredential{} } |
| 134 | |
| 135 | func (rc *perRPCCredential) RequireTransportSecurity() bool { return false } |
| 136 | |
| 137 | func (rc *perRPCCredential) GetRequestMetadata(ctx context.Context, s ...string) (map[string]string, error) { |
| 138 | rc.authTokenMu.RLock() |
| 139 | authToken := rc.authToken |
| 140 | rc.authTokenMu.RUnlock() |
| 141 | return map[string]string{rpctypes.TokenFieldNameGRPC: authToken}, nil |
| 142 | } |
| 143 | |
| 144 | func (b *bundle) UpdateAuthToken(token string) { |
| 145 | if b.rc == nil { |
| 146 | return |
| 147 | } |
| 148 | b.rc.UpdateAuthToken(token) |
| 149 | } |
| 150 | |
| 151 | func (rc *perRPCCredential) UpdateAuthToken(token string) { |
| 152 | rc.authTokenMu.Lock() |
| 153 | rc.authToken = token |
| 154 | rc.authTokenMu.Unlock() |
| 155 | } |