mirror of
https://github.com/gravitational/teleport.git
synced 2026-10-31 20:39:37 +08:00
Andrew LeFevre
de2e55bb69
To prevent users from being able to directly connect to registered OpenSSH (Agentless) nodes, the OpenSSH CA was introduced. When connecting to Agentless nodes, the Proxy will forward the connection so the session can be recorded. The forwarding SSH server is configured to authenticate to the target node with a certificate signed by OpenSSH CA, which users do not have access to.
79 lines
2.3 KiB
Go
79 lines
2.3 KiB
Go
/*
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Copyright 2023 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 agentless provides functions to allow connecting to registered
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// OpenSSH (agentless) nodes.
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package agentless
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import (
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"context"
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"time"
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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/client/proto"
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"github.com/gravitational/teleport/api/utils/sshutils"
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"github.com/gravitational/teleport/lib/auth"
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"github.com/gravitational/teleport/lib/auth/native"
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)
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// SiteClientGetter returns an auth client to a given cluster.
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type SiteClientGetter interface {
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GetSiteClient(ctx context.Context, clusterName string) (auth.ClientI, error)
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}
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// CreateAuthSigner attempts to create a [ssh.Signer] that is signed with
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// OpenSSH CA and can be used to authenticate to agentless nodes.
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func CreateAuthSigner(ctx context.Context, username, clusterName string, ttl time.Duration, clientGetter SiteClientGetter) (ssh.Signer, error) {
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// generate a new key pair
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priv, err := native.GeneratePrivateKey()
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if err != nil {
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return nil, trace.Wrap(err)
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}
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// sign new public key with OpenSSH CA
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client, err := clientGetter.GetSiteClient(ctx, clusterName)
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if err != nil {
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return nil, trace.Wrap(err)
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}
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reply, err := client.GenerateOpenSSHCert(ctx, &proto.OpenSSHCertRequest{
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Username: username,
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PublicKey: priv.MarshalSSHPublicKey(),
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TTL: proto.Duration(ttl),
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Cluster: clusterName,
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})
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if err != nil {
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return nil, trace.Wrap(err)
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}
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// parse returned certificate bytes and create a signer with it
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cert, err := sshutils.ParseCertificate(reply.Cert)
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if err != nil {
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return nil, trace.Wrap(err)
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}
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privSigner, err := ssh.NewSignerFromSigner(priv.Signer)
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if err != nil {
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return nil, trace.Wrap(err)
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}
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signer, err := ssh.NewCertSigner(cert, privSigner)
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if err != nil {
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return nil, trace.Wrap(err)
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}
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return signer, nil
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}
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