mirror of
https://github.com/gravitational/teleport.git
synced 2026-11-01 13:39:37 +08:00
Jakub Nyckowski
d68c90929f
This change introduces a workaround for OpenSSH 7.x bug related to SHA-2 signed certificates. Teleport signs all certificates with SHA-2-512, which prevents us from connecting to older sshd. As a workaround, we will send the same certificate signed with SHA-2-512 (as we do right now) and SHA-1 if the first authentication fails. We always send the SHA-2 certificates first, so newer OpenSSH versions should always use SHA-2 certs as they do right now.
77 lines
2.4 KiB
Go
77 lines
2.4 KiB
Go
/*
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Copyright 2015-2017 Gravitational, Inc.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package sshutils
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import (
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"crypto"
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"io"
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"github.com/gravitational/trace"
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"golang.org/x/crypto/ssh"
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"github.com/gravitational/teleport/api/utils/sshutils"
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)
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// LegacySHA1Signer always forces use of SHA-1 for signing. It should be not
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// be used until necessary.
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// This struct should not implement SignWithAlgorithm() method
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// from ssh.AlgorithmSigner interface. This would break the SHA-1 signing.
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type LegacySHA1Signer struct {
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Signer ssh.AlgorithmSigner
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}
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// PublicKey returns the public key from the underlying signer.
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func (s *LegacySHA1Signer) PublicKey() ssh.PublicKey {
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return s.Signer.PublicKey()
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}
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// Sign forces the SHA-1 signature.
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func (s *LegacySHA1Signer) Sign(rand io.Reader, data []byte) (*ssh.Signature, error) {
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return s.Signer.SignWithAlgorithm(rand, data, ssh.KeyAlgoRSA)
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}
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// NewSigner returns new ssh Signer from private key + certificate pair. The
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// signer can be used to create "auth methods" i.e. login into Teleport SSH
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// servers.
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func NewSigner(keyBytes, certBytes []byte) (ssh.Signer, error) {
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keySigner, err := ssh.ParsePrivateKey(keyBytes)
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if err != nil {
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return nil, trace.Wrap(err, "failed to parse SSH private key")
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}
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cert, err := sshutils.ParseCertificate(certBytes)
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if err != nil {
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return nil, trace.Wrap(err, "failed to parse SSH certificate")
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}
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return ssh.NewCertSigner(cert, keySigner)
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}
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// CryptoPublicKey extracts public key from RSA public key in authorized_keys format
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func CryptoPublicKey(publicKey []byte) (crypto.PublicKey, error) {
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// reuse the same RSA keys for SSH and TLS keys
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pubKey, _, _, _, err := ssh.ParseAuthorizedKey(publicKey)
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if err != nil {
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return nil, trace.Wrap(err)
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}
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cryptoPubKey, ok := pubKey.(ssh.CryptoPublicKey)
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if !ok {
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return nil, trace.BadParameter("expected ssh.CryptoPublicKey, got %T", pubKey)
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}
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return cryptoPubKey.CryptoPublicKey(), nil
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}
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