mirror of
https://github.com/gravitational/teleport.git
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105 lines
3.0 KiB
Go
105 lines
3.0 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/teleport/api/utils/sshutils"
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"golang.org/x/crypto/ssh"
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"github.com/gravitational/trace"
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)
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// AlgSigner wraps the provided ssh.Signer to ensure signature algorithm
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// compatibility with OpenSSH.
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//
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// Right now it allows forcing SHA-2 signatures with RSA keys, instead of the
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// default SHA-1 used by x/crypto/ssh. See
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// https://www.openssh.com/txt/release-8.2 for context.
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//
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// If the provided Signer is not an RSA key or does not implement
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// ssh.AlgorithmSigner, it's returned as is.
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//
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// DELETE IN 5.0: assuming https://github.com/golang/go/issues/37278 is fixed
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// by then and we pull in the fix. Also delete all call sites.
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func AlgSigner(s ssh.Signer, alg string) ssh.Signer {
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if alg == "" {
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return s
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}
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if s.PublicKey().Type() != ssh.KeyAlgoRSA && s.PublicKey().Type() != ssh.CertAlgoRSAv01 {
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return s
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}
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as, ok := s.(ssh.AlgorithmSigner)
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if !ok {
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return s
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}
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return fixedAlgorithmSigner{
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AlgorithmSigner: as,
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alg: alg,
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}
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}
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type fixedAlgorithmSigner struct {
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ssh.AlgorithmSigner
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alg string
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}
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func (s fixedAlgorithmSigner) SignWithAlgorithm(rand io.Reader, data []byte, alg string) (*ssh.Signature, error) {
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if alg == "" {
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alg = s.alg
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}
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return s.AlgorithmSigner.SignWithAlgorithm(rand, data, alg)
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}
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func (s fixedAlgorithmSigner) Sign(rand io.Reader, data []byte) (*ssh.Signature, error) {
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return s.AlgorithmSigner.SignWithAlgorithm(rand, data, s.alg)
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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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