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 | 525 |
1 files changed, 0 insertions, 525 deletions
diff --git a/vendor/golang.org/x/crypto/ssh/client_auth.go b/vendor/golang.org/x/crypto/ssh/client_auth.go deleted file mode 100644 index 5f44b77..0000000 --- a/vendor/golang.org/x/crypto/ssh/client_auth.go +++ /dev/null @@ -1,525 +0,0 @@ -// Copyright 2011 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -package ssh - -import ( - "bytes" - "errors" - "fmt" - "io" -) - -type authResult int - -const ( - authFailure authResult = iota - authPartialSuccess - authSuccess -) - -// clientAuthenticate authenticates with the remote server. See RFC 4252. -func (c *connection) clientAuthenticate(config *ClientConfig) error { - // initiate user auth session - if err := c.transport.writePacket(Marshal(&serviceRequestMsg{serviceUserAuth})); err != nil { - return err - } - packet, err := c.transport.readPacket() - if err != nil { - return err - } - var serviceAccept serviceAcceptMsg - if err := Unmarshal(packet, &serviceAccept); err != nil { - return err - } - - // during the authentication phase the client first attempts the "none" method - // then any untried methods suggested by the server. - tried := make(map[string]bool) - var lastMethods []string - - sessionID := c.transport.getSessionID() - for auth := AuthMethod(new(noneAuth)); auth != nil; { - ok, methods, err := auth.auth(sessionID, config.User, c.transport, config.Rand) - if err != nil { - return err - } - if ok == authSuccess { - // success - return nil - } else if ok == authFailure { - tried[auth.method()] = true - } - if methods == nil { - methods = lastMethods - } - lastMethods = methods - - auth = nil - - findNext: - for _, a := range config.Auth { - candidateMethod := a.method() - if tried[candidateMethod] { - continue - } - for _, meth := range methods { - if meth == candidateMethod { - auth = a - break findNext - } - } - } - } - return fmt.Errorf("ssh: unable to authenticate, attempted methods %v, no supported methods remain", keys(tried)) -} - -func keys(m map[string]bool) []string { - s := make([]string, 0, len(m)) - - for key := range m { - s = append(s, key) - } - return s -} - -// An AuthMethod represents an instance of an RFC 4252 authentication method. -type AuthMethod interface { - // auth authenticates user over transport t. - // Returns true if authentication is successful. - // 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) - - // method returns the RFC 4252 method name. - method() string -} - -// "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) { - if err := c.writePacket(Marshal(&userAuthRequestMsg{ - User: user, - Service: serviceSSH, - Method: "none", - })); err != nil { - return authFailure, nil, err - } - - return handleAuthResponse(c) -} - -func (n *noneAuth) method() string { - return "none" -} - -// passwordCallback is an AuthMethod that fetches the password through -// 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) { - type passwordAuthMsg struct { - User string `sshtype:"50"` - Service string - Method string - Reply bool - Password string - } - - pw, err := cb() - // REVIEW NOTE: is there a need to support skipping a password attempt? - // The program may only find out that the user doesn't have a password - // when prompting. - if err != nil { - return authFailure, nil, err - } - - if err := c.writePacket(Marshal(&passwordAuthMsg{ - User: user, - Service: serviceSSH, - Method: cb.method(), - Reply: false, - Password: pw, - })); err != nil { - return authFailure, nil, err - } - - return handleAuthResponse(c) -} - -func (cb passwordCallback) method() string { - return "password" -} - -// Password returns an AuthMethod using the given password. -func Password(secret string) AuthMethod { - return passwordCallback(func() (string, error) { return secret, nil }) -} - -// PasswordCallback returns an AuthMethod that uses a callback for -// fetching a password. -func PasswordCallback(prompt func() (secret string, err error)) AuthMethod { - return passwordCallback(prompt) -} - -type publickeyAuthMsg struct { - User string `sshtype:"50"` - Service string - Method string - // HasSig indicates to the receiver packet that the auth request is signed and - // should be used for authentication of the request. - HasSig bool - Algoname string - PubKey []byte - // Sig is tagged with "rest" so Marshal will exclude it during - // validateKey - Sig []byte `ssh:"rest"` -} - -// publicKeyCallback is an AuthMethod that uses a set of key -// pairs for authentication. -type publicKeyCallback func() ([]Signer, error) - -func (cb publicKeyCallback) method() string { - return "publickey" -} - -func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader) (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 - // the process with the remaining keys. - - signers, err := cb() - if err != nil { - return authFailure, nil, err - } - var methods []string - for _, signer := range signers { - ok, err := validateKey(signer.PublicKey(), user, c) - if err != nil { - return authFailure, nil, err - } - if !ok { - continue - } - - pub := signer.PublicKey() - pubKey := pub.Marshal() - sign, err := signer.Sign(rand, buildDataSignedForAuth(session, userAuthRequestMsg{ - User: user, - Service: serviceSSH, - Method: cb.method(), - }, []byte(pub.Type()), pubKey)) - if err != nil { - return authFailure, nil, err - } - - // manually wrap the serialized signature in a string - s := Marshal(sign) - sig := make([]byte, stringLength(len(s))) - marshalString(sig, s) - msg := publickeyAuthMsg{ - User: user, - Service: serviceSSH, - Method: cb.method(), - HasSig: true, - Algoname: pub.Type(), - PubKey: pubKey, - Sig: sig, - } - p := Marshal(&msg) - if err := c.writePacket(p); err != nil { - return authFailure, nil, err - } - var success authResult - success, methods, err = handleAuthResponse(c) - if err != nil { - return authFailure, nil, err - } - - // If authentication succeeds or the list of available methods does not - // contain the "publickey" method, do not attempt to authenticate with any - // other keys. According to RFC 4252 Section 7, the latter can occur when - // additional authentication methods are required. - if success == authSuccess || !containsMethod(methods, cb.method()) { - return success, methods, err - } - } - - return authFailure, methods, nil -} - -func containsMethod(methods []string, method string) bool { - for _, m := range methods { - if m == method { - return true - } - } - - return false -} - -// validateKey validates the key provided is acceptable to the server. -func validateKey(key PublicKey, user string, c packetConn) (bool, error) { - pubKey := key.Marshal() - msg := publickeyAuthMsg{ - User: user, - Service: serviceSSH, - Method: "publickey", - HasSig: false, - Algoname: key.Type(), - PubKey: pubKey, - } - if err := c.writePacket(Marshal(&msg)); err != nil { - return false, err - } - - return confirmKeyAck(key, c) -} - -func confirmKeyAck(key PublicKey, c packetConn) (bool, error) { - pubKey := key.Marshal() - algoname := key.Type() - - for { - packet, err := c.readPacket() - if err != nil { - return false, err - } - switch packet[0] { - case msgUserAuthBanner: - if err := handleBannerResponse(c, packet); err != nil { - return false, err - } - case msgUserAuthPubKeyOk: - var msg userAuthPubKeyOkMsg - if err := Unmarshal(packet, &msg); err != nil { - return false, err - } - if msg.Algo != algoname || !bytes.Equal(msg.PubKey, pubKey) { - return false, nil - } - return true, nil - case msgUserAuthFailure: - return false, nil - default: - return false, unexpectedMessageError(msgUserAuthSuccess, packet[0]) - } - } -} - -// PublicKeys returns an AuthMethod that uses the given key -// pairs. -func PublicKeys(signers ...Signer) AuthMethod { - return publicKeyCallback(func() ([]Signer, error) { return signers, nil }) -} - -// PublicKeysCallback returns an AuthMethod that runs the given -// function to obtain a list of key pairs. -func PublicKeysCallback(getSigners func() (signers []Signer, err error)) AuthMethod { - return publicKeyCallback(getSigners) -} - -// handleAuthResponse returns whether the preceding authentication request succeeded -// 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) { - for { - packet, err := c.readPacket() - if err != nil { - return authFailure, nil, err - } - - switch packet[0] { - case msgUserAuthBanner: - if err := handleBannerResponse(c, packet); err != nil { - return authFailure, nil, err - } - case msgUserAuthFailure: - var msg userAuthFailureMsg - if err := Unmarshal(packet, &msg); err != nil { - return authFailure, nil, err - } - if msg.PartialSuccess { - return authPartialSuccess, msg.Methods, nil - } - return authFailure, msg.Methods, nil - case msgUserAuthSuccess: - return authSuccess, nil, nil - default: - return authFailure, nil, unexpectedMessageError(msgUserAuthSuccess, packet[0]) - } - } -} - -func handleBannerResponse(c packetConn, packet []byte) error { - var msg userAuthBannerMsg - if err := Unmarshal(packet, &msg); err != nil { - return err - } - - transport, ok := c.(*handshakeTransport) - if !ok { - return nil - } - - if transport.bannerCallback != nil { - return transport.bannerCallback(msg.Message) - } - - return nil -} - -// KeyboardInteractiveChallenge should print questions, optionally -// 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 -// 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) - -// KeyboardInteractive returns an AuthMethod using a prompt/response -// sequence controlled by the server. -func KeyboardInteractive(challenge KeyboardInteractiveChallenge) AuthMethod { - return challenge -} - -func (cb KeyboardInteractiveChallenge) method() string { - return "keyboard-interactive" -} - -func (cb KeyboardInteractiveChallenge) auth(session []byte, user string, c packetConn, rand io.Reader) (authResult, []string, error) { - type initiateMsg struct { - User string `sshtype:"50"` - Service string - Method string - Language string - Submethods string - } - - if err := c.writePacket(Marshal(&initiateMsg{ - User: user, - Service: serviceSSH, - Method: "keyboard-interactive", - })); err != nil { - return authFailure, nil, err - } - - for { - packet, err := c.readPacket() - if err != nil { - return authFailure, nil, err - } - - // like handleAuthResponse, but with less options. - switch packet[0] { - case msgUserAuthBanner: - if err := handleBannerResponse(c, packet); err != nil { - return authFailure, nil, err - } - continue - case msgUserAuthInfoRequest: - // OK - case msgUserAuthFailure: - var msg userAuthFailureMsg - if err := Unmarshal(packet, &msg); err != nil { - return authFailure, nil, err - } - if msg.PartialSuccess { - return authPartialSuccess, msg.Methods, nil - } - return authFailure, msg.Methods, nil - case msgUserAuthSuccess: - return authSuccess, nil, nil - default: - return authFailure, nil, unexpectedMessageError(msgUserAuthInfoRequest, packet[0]) - } - - var msg userAuthInfoRequestMsg - if err := Unmarshal(packet, &msg); err != nil { - return authFailure, nil, err - } - - // Manually unpack the prompt/echo pairs. - rest := msg.Prompts - var prompts []string - var echos []bool - for i := 0; i < int(msg.NumPrompts); i++ { - prompt, r, ok := parseString(rest) - if !ok || len(r) == 0 { - return authFailure, nil, errors.New("ssh: prompt format error") - } - prompts = append(prompts, string(prompt)) - echos = append(echos, r[0] != 0) - rest = r[1:] - } - - if len(rest) != 0 { - return authFailure, nil, errors.New("ssh: extra data following keyboard-interactive pairs") - } - - answers, err := cb(msg.User, msg.Instruction, prompts, echos) - if err != nil { - return authFailure, nil, err - } - - if len(answers) != len(prompts) { - return authFailure, nil, errors.New("ssh: not enough answers from keyboard-interactive callback") - } - responseLength := 1 + 4 - for _, a := range answers { - responseLength += stringLength(len(a)) - } - serialized := make([]byte, responseLength) - p := serialized - p[0] = msgUserAuthInfoResponse - p = p[1:] - p = marshalUint32(p, uint32(len(answers))) - for _, a := range answers { - p = marshalString(p, []byte(a)) - } - - if err := c.writePacket(serialized); err != nil { - return authFailure, nil, err - } - } -} - -type retryableAuthMethod struct { - authMethod AuthMethod - maxTries int -} - -func (r *retryableAuthMethod) auth(session []byte, user string, c packetConn, rand io.Reader) (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) - if ok != authFailure || err != nil { // either success, partial success or error terminate - return ok, methods, err - } - } - return ok, methods, err -} - -func (r *retryableAuthMethod) method() string { - return r.authMethod.method() -} - -// RetryableAuthMethod is a decorator for other auth methods enabling them to -// be retried up to maxTries before considering that AuthMethod itself failed. -// If maxTries is <= 0, will retry indefinitely -// -// This is useful for interactive clients using challenge/response type -// authentication (e.g. Keyboard-Interactive, Password, etc) where the user -// could mistype their response resulting in the server issuing a -// SSH_MSG_USERAUTH_FAILURE (rfc4252 #8 [password] and rfc4256 #3.4 -// [keyboard-interactive]); Without this decorator, the non-retryable -// AuthMethod would be removed from future consideration, and never tried again -// (and so the user would never be able to retry their entry). -func RetryableAuthMethod(auth AuthMethod, maxTries int) AuthMethod { - return &retryableAuthMethod{authMethod: auth, maxTries: maxTries} -} |