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 | 96 |
1 files changed, 66 insertions, 30 deletions
diff --git a/vendor/golang.org/x/crypto/ssh/client_auth.go b/vendor/golang.org/x/crypto/ssh/client_auth.go index 409b5ea1d..5c3bc2572 100644 --- a/vendor/golang.org/x/crypto/ssh/client_auth.go +++ b/vendor/golang.org/x/crypto/ssh/client_auth.go @@ -71,7 +71,9 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error { for auth := AuthMethod(new(noneAuth)); auth != nil; { ok, methods, err := auth.auth(sessionID, config.User, c.transport, config.Rand, extensions) if err != nil { - return err + // We return the error later if there is no other method left to + // try. + ok = authFailure } if ok == authSuccess { // success @@ -101,6 +103,12 @@ func (c *connection) clientAuthenticate(config *ClientConfig) error { } } } + + if auth == nil && err != nil { + // We have an error and there are no other authentication methods to + // try, so we return it. + return err + } } return fmt.Errorf("ssh: unable to authenticate, attempted methods %v, no supported methods remain", tried) } @@ -217,21 +225,45 @@ func (cb publicKeyCallback) method() string { return "publickey" } -func pickSignatureAlgorithm(signer Signer, extensions map[string][]byte) (as AlgorithmSigner, algo string) { +func pickSignatureAlgorithm(signer Signer, extensions map[string][]byte) (MultiAlgorithmSigner, string, error) { + var as MultiAlgorithmSigner 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 + // If the signer implements MultiAlgorithmSigner we use the algorithms it + // support, if it implements AlgorithmSigner we assume it supports all + // algorithms, otherwise only the key format one. + switch s := signer.(type) { + case MultiAlgorithmSigner: + as = s + case AlgorithmSigner: + as = &multiAlgorithmSigner{ + AlgorithmSigner: s, + supportedAlgorithms: algorithmsForKeyFormat(underlyingAlgo(keyFormat)), + } + default: + as = &multiAlgorithmSigner{ + AlgorithmSigner: algorithmSignerWrapper{signer}, + supportedAlgorithms: []string{underlyingAlgo(keyFormat)}, + } + } + + getFallbackAlgo := func() (string, error) { + // Fallback to use if there is no "server-sig-algs" extension or a + // common algorithm cannot be found. We use the public key format if the + // MultiAlgorithmSigner supports it, otherwise we return an error. + if !contains(as.Algorithms(), underlyingAlgo(keyFormat)) { + return "", fmt.Errorf("ssh: no common public key signature algorithm, server only supports %q for key type %q, signer only supports %v", + underlyingAlgo(keyFormat), keyFormat, as.Algorithms()) + } + return keyFormat, nil } 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 + // If there is no "server-sig-algs" extension use the fallback + // algorithm. + algo, err := getFallbackAlgo() + return as, algo, err } // The server-sig-algs extension only carries underlying signature @@ -245,15 +277,22 @@ func pickSignatureAlgorithm(signer Signer, extensions map[string][]byte) (as Alg } } - keyAlgos := algorithmsForKeyFormat(keyFormat) + // Filter algorithms based on those supported by MultiAlgorithmSigner. + var keyAlgos []string + for _, algo := range algorithmsForKeyFormat(keyFormat) { + if contains(as.Algorithms(), underlyingAlgo(algo)) { + keyAlgos = append(keyAlgos, algo) + } + } + 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 + // If there is no overlap, return the fallback algorithm to support + // servers that fail to list all supported algorithms. + algo, err := getFallbackAlgo() + return as, algo, err } - return as, algo + return as, algo, nil } func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand io.Reader, extensions map[string][]byte) (authResult, []string, error) { @@ -267,10 +306,17 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand return authFailure, nil, err } var methods []string + var errSigAlgo error for _, signer := range signers { pub := signer.PublicKey() - as, algo := pickSignatureAlgorithm(signer, extensions) - + as, algo, err := pickSignatureAlgorithm(signer, extensions) + if err != nil && errSigAlgo == nil { + // If we cannot negotiate a signature algorithm store the first + // error so we can return it to provide a more meaningful message if + // no other signers work. + errSigAlgo = err + continue + } ok, err := validateKey(pub, algo, user, c) if err != nil { return authFailure, nil, err @@ -317,22 +363,12 @@ func (cb publicKeyCallback) auth(session []byte, user string, c packetConn, rand // 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()) { + if success == authSuccess || !contains(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 + return authFailure, methods, errSigAlgo } // validateKey validates the key provided is acceptable to the server. |