diff options
Diffstat (limited to 'vendor/golang.org/x/crypto/ssh/client_auth.go')
| -rw-r--r-- | vendor/golang.org/x/crypto/ssh/client_auth.go | 132 |
1 files changed, 108 insertions, 24 deletions
diff --git a/vendor/golang.org/x/crypto/ssh/client_auth.go b/vendor/golang.org/x/crypto/ssh/client_auth.go index c611aeb6..409b5ea1 100644 --- a/vendor/golang.org/x/crypto/ssh/client_auth.go +++ b/vendor/golang.org/x/crypto/ssh/client_auth.go @@ -9,6 +9,7 @@ import ( "errors" "fmt" "io" + "strings" ) type authResult int @@ -29,6 +30,33 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error { if err != nil { return err } + // The server may choose to send a SSH_MSG_EXT_INFO at this point (if we + // advertised willingness to receive one, which we always do) or not. See + // RFC 8308, Section 2.4. + extensions := make(map[string][]byte) + if len(packet) > 0 && packet[0] == msgExtInfo { + var extInfo extInfoMsg + if err := Unmarshal(packet, &extInfo); err != nil { + return err + } + payload := extInfo.Payload + for i := uint32(0); i < extInfo.NumExtensions; i++ { + name, rest, ok := parseString(payload) + if !ok { + return parseError(msgExtInfo) + } + value, rest, ok := parseString(rest) + if !ok { + return parseError(msgExtInfo) + } + extensions[string(name)] = value + payload = rest + } + packet, err = c.transport.readPacket() + if err != nil { + return err + } + } var serviceAccept serviceAcceptMsg if err := Unmarshal(packet, &serviceAccept); err != nil { return err @@ -41,7 +69,7 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error { sessionID := c.transport.getSessionID() for auth := AuthMethod(new(noneAuth)); auth != nil; { - ok, methods, err := auth.auth(sessionID, config.User, c.transport, config.Rand) + ok, methods, err := auth.auth(sessionID, config.User, c.transport, config.Rand, extensions) if err != nil { return err } @@ -93,7 +121,7 @@ type AuthMethod interface { // If authentication is not successful, a []string of alternative // method names is returned. If the slice is nil, it will be ignored // and the previous set of possible methods will be reused. - auth(session []byte, user string, p packetConn, rand io.Reader) (authResult, []string, error) + auth(session []byte, user string, p packetConn, rand io.Reader, extensions map[string][]byte) (authResult, []string, error) // method returns the RFC 4252 method name. method() string @@ -102,7 +130,7 @@ type AuthMethod interface { // "none" authentication, RFC 4252 section 5.2. type noneAuth int -func (n *noneAuth) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) { +func (n *noneAuth) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) { if err := c.writePacket(Marshal(&userAuthRequestMsg{ User: user, Service: serviceSSH, @@ -122,7 +150,7 @@ func (n *noneAuth) method() string { // a function call, e.g. by prompting the user. type passwordCallback func() (password string, err error) -func (cb passwordCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) { +func (cb passwordCallback) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) { type passwordAuthMsg struct { User string `sshtype:"50"` Service string @@ -189,7 +217,46 @@ func (cb publicKeyCallback) method() string { return "publickey" } -func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) { +func pickSignatureAlgorithm(signer Signer, extensions map[string][]byte) (as AlgorithmSigner, algo string) { + keyFormat := signer.PublicKey().Type() + + // Like in sendKexInit, if the public key implements AlgorithmSigner we + // assume it supports all algorithms, otherwise only the key format one. + as, ok := signer.(AlgorithmSigner) + if !ok { + return algorithmSignerWrapper{signer}, keyFormat + } + + extPayload, ok := extensions["server-sig-algs"] + if !ok { + // If there is no "server-sig-algs" extension, fall back to the key + // format algorithm. + return as, keyFormat + } + + // The server-sig-algs extension only carries underlying signature + // algorithm, but we are trying to select a protocol-level public key + // algorithm, which might be a certificate type. Extend the list of server + // supported algorithms to include the corresponding certificate algorithms. + serverAlgos := strings.Split(string(extPayload), ",") + for _, algo := range serverAlgos { + if certAlgo, ok := certificateAlgo(algo); ok { + serverAlgos = append(serverAlgos, certAlgo) + } + } + + keyAlgos := algorithmsForKeyFormat(keyFormat) + algo, err := findCommon("public key signature algorithm", keyAlgos, serverAlgos) + if err != nil { + // If there is no overlap, try the key anyway with the key format + // algorithm, to support servers that fail to list all supported + // algorithms. + return as, keyFormat + } + return as, algo +} + +func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader, extensions map[string][]byte) (authResult, []string, error) { // Authentication is performed by sending an enquiry to test if a key is // acceptable to the remote. If the key is acceptable, the client will // attempt to authenticate with the valid key. If not the client will repeat @@ -201,7 +268,10 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand } var methods []string for _, signer := range signers { - ok, err := validateKey(signer.PublicKey(), user, c) + pub := signer.PublicKey() + as, algo := pickSignatureAlgorithm(signer, extensions) + + ok, err := validateKey(pub, algo, user, c) if err != nil { return authFailure, nil, err } @@ -209,13 +279,13 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand continue } - pub := signer.PublicKey() pubKey := pub.Marshal() - sign, err := signer.Sign(rand, buildDataSignedForAuth(session, userAuthRequestMsg{ + data := buildDataSignedForAuth(session, userAuthRequestMsg{ User: user, Service: serviceSSH, Method: cb.method(), - }, []byte(pub.Type()), pubKey)) + }, algo, pubKey) + sign, err := as.SignWithAlgorithm(rand, data, underlyingAlgo(algo)) if err != nil { return authFailure, nil, err } @@ -229,7 +299,7 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand Service: serviceSSH, Method: cb.method(), HasSig: true, - Algoname: pub.Type(), + Algoname: algo, PubKey: pubKey, Sig: sig, } @@ -266,26 +336,25 @@ func containsMethod(methods []string, method string) bool { } // validateKey validates the key provided is acceptable to the server. -func validateKey(key PublicKey, user string, c packetConn) (bool, error) { +func validateKey(key PublicKey, algo string, user string, c packetConn) (bool, error) { pubKey := key.Marshal() msg := publickeyAuthMsg{ User: user, Service: serviceSSH, Method: "publickey", HasSig: false, - Algoname: key.Type(), + Algoname: algo, PubKey: pubKey, } if err := c.writePacket(Marshal(&msg)); err != nil { return false, err } - return confirmKeyAck(key, c) + return confirmKeyAck(key, algo, c) } -func confirmKeyAck(key PublicKey, c packetConn) (bool, error) { +func confirmKeyAck(key PublicKey, algo string, c packetConn) (bool, error) { pubKey := key.Marshal() - algoname := key.Type() for { packet, err := c.readPacket() @@ -302,14 +371,14 @@ func confirmKeyAck(key PublicKey, c packetConn) (bool, error) { if err := Unmarshal(packet, &msg); err != nil { return false, err } - if msg.Algo != algoname || !bytes.Equal(msg.PubKey, pubKey) { + if msg.Algo != algo || !bytes.Equal(msg.PubKey, pubKey) { return false, nil } return true, nil case msgUserAuthFailure: return false, nil default: - return false, unexpectedMessageError(msgUserAuthSuccess, packet[0]) + return false, unexpectedMessageError(msgUserAuthPubKeyOk, packet[0]) } } } @@ -330,6 +399,7 @@ func PublicKeysCallback(getSigners func() (signers []Signer, err error)) AuthMet // along with a list of remaining authentication methods to try next and // an error if an unexpected response was received. func handleAuthResponse(c packetConn) (authResult, []string, error) { + gotMsgExtInfo := false for { packet, err := c.readPacket() if err != nil { @@ -341,6 +411,12 @@ func handleAuthResponse(c packetConn) (authResult, []string, error) { if err := handleBannerResponse(c, packet); err != nil { return authFailure, nil, err } + case msgExtInfo: + // Ignore post-authentication RFC 8308 extensions, once. + if gotMsgExtInfo { + return authFailure, nil, unexpectedMessageError(msgUserAuthSuccess, packet[0]) + } + gotMsgExtInfo = true case msgUserAuthFailure: var msg userAuthFailureMsg if err := Unmarshal(packet, &msg); err != nil { @@ -380,10 +456,10 @@ func handleBannerResponse(c packetConn, packet []byte) error { // disabling echoing (e.g. for passwords), and return all the answers. // Challenge may be called multiple times in a single session. After // successful authentication, the server may send a challenge with no -// questions, for which the user and instruction messages should be +// questions, for which the name and instruction messages should be // printed. RFC 4256 section 3.3 details how the UI should behave for // both CLI and GUI environments. -type KeyboardInteractiveChallenge func(user, instruction string, questions []string, echos []bool) (answers []string, err error) +type KeyboardInteractiveChallenge func(name, instruction string, questions []string, echos []bool) (answers []string, err error) // KeyboardInteractive returns an AuthMethod using a prompt/response // sequence controlled by the server. @@ -395,7 +471,7 @@ func (cb KeyboardInteractiveChallenge) method() string { return "keyboard-interactive" } -func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) { +func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) { type initiateMsg struct { User string `sshtype:"50"` Service string @@ -412,6 +488,7 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe return authFailure, nil, err } + gotMsgExtInfo := false for { packet, err := c.readPacket() if err != nil { @@ -425,6 +502,13 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe return authFailure, nil, err } continue + case msgExtInfo: + // Ignore post-authentication RFC 8308 extensions, once. + if gotMsgExtInfo { + return authFailure, nil, unexpectedMessageError(msgUserAuthInfoRequest, packet[0]) + } + gotMsgExtInfo = true + continue case msgUserAuthInfoRequest: // OK case msgUserAuthFailure: @@ -465,7 +549,7 @@ func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packe return authFailure, nil, errors.New("ssh: extra data following keyboard-interactive pairs") } - answers, err := cb(msg.User, msg.Instruction, prompts, echos) + answers, err := cb(msg.Name, msg.Instruction, prompts, echos) if err != nil { return authFailure, nil, err } @@ -497,9 +581,9 @@ type retryableAuthMethod struct { maxTries int } -func (r *retryableAuthMethod) auth(session []byte, user string, c packetConn, rand io.Reader) (ok authResult, methods []string, err error) { +func (r *retryableAuthMethod) auth(session []byte, user string, c packetConn, rand io.Reader, extensions map[string][]byte) (ok authResult, methods []string, err error) { for i := 0; r.maxTries <= 0 || i < r.maxTries; i++ { - ok, methods, err = r.authMethod.auth(session, user, c, rand) + ok, methods, err = r.authMethod.auth(session, user, c, rand, extensions) if ok != authFailure || err != nil { // either success, partial success or error terminate return ok, methods, err } @@ -542,7 +626,7 @@ type gssAPIWithMICCallback struct { target string } -func (g *gssAPIWithMICCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) { +func (g *gssAPIWithMICCallback) auth(session []byte, user string, c packetConn, rand io.Reader, _ map[string][]byte) (authResult, []string, error) { m := &userAuthRequestMsg{ User: user, Service: serviceSSH, |