Jon Chery
107 lines
3.5 KiB
Go
107 lines
3.5 KiB
Go
package security
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import (
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"crypto/ed25519"
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"crypto/rand"
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"crypto/x509"
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"encoding/pem"
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"errors"
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"fmt"
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"os"
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"path/filepath"
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"golang.org/x/crypto/ssh"
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)
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// SSHKeyMode is the file mode for the SSH private key. Matches the
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// CA key mode (REQ-033 spirit: 0600 for private keys).
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const SSHKeyMode os.FileMode = 0o600
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// SSHPubMode is the file mode for the SSH public key (authorized_keys
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// line). Matches the CA cert mode (0644 for public material).
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const SSHPubMode os.FileMode = 0o644
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const (
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sshKeyFile = "orca_ssh_key"
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sshPubFile = "orca_ssh_key.pub"
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)
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// SSHFingerprintSHA256 returns the canonical SSH public-key fingerprint
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// in the form `SHA256:base64` (no trailing padding), as produced by
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// `ssh-keygen -lf` and OpenSSH's host-key verification prompts. This is
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// a thin wrapper over ssh.FingerprintSHA256 (AD-027) for use by the
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// proxmox bootstrap pinned-host-key callback (REQ-058) and any other
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// SSH-domain identity checks. Do NOT reuse security.Fingerprint — that
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// returns an X.509 DER hex digest (different domain; RESEARCH §2.2).
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func SSHFingerprintSHA256(pubKey ssh.PublicKey) string {
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return ssh.FingerprintSHA256(pubKey)
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}
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// GenerateOrLoadSSHKey returns the orca SSH keypair, generating it
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// lazily on first call (D-037). The key is Ed25519 (smaller, faster,
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// more secure than RSA for SSH auth), persisted as PKCS8 PEM to
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// dir/orca_ssh_key (0600) and dir/orca_ssh_key.pub (0644).
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//
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// Idempotent: if both files exist with valid content, they are loaded
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// and returned without regeneration. This matches the CAInit fast-path
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// pattern (D-036 idempotency).
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//
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// Returns:
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// - keyPEM: PKCS8 PEM private key (parses with ssh.ParsePrivateKey)
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// - pubLine: authorized_keys line (ssh-ed25519 AAAA... comment\n)
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func GenerateOrLoadSSHKey(dir string) (keyPEM, pubLine []byte, err error) {
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if dir == "" {
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return nil, nil, errors.New("GenerateOrLoadSSHKey: dir is required")
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}
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if err := os.MkdirAll(dir, 0o755); err != nil {
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return nil, nil, fmt.Errorf("GenerateOrLoadSSHKey: mkdir: %w", err)
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}
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keyPath := filepath.Join(dir, sshKeyFile)
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pubPath := filepath.Join(dir, sshPubFile)
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// Fast path: existing key — load and return.
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if ok, err := bothExist(keyPath, pubPath); err != nil {
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return nil, nil, err
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} else if ok {
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keyPEM, err := os.ReadFile(keyPath)
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if err != nil {
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return nil, nil, fmt.Errorf("read SSH key: %w", err)
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}
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pubLine, err := os.ReadFile(pubPath)
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if err != nil {
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return nil, nil, fmt.Errorf("read SSH pub: %w", err)
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}
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return keyPEM, pubLine, nil
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}
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// Generate Ed25519 keypair.
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pub, priv, err := ed25519.GenerateKey(rand.Reader)
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if err != nil {
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return nil, nil, fmt.Errorf("GenerateOrLoadSSHKey: ed25519 gen: %w", err)
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}
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// Serialize private key as PKCS8 PEM (consistent with ca.key/server.key).
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keyDER, err := x509.MarshalPKCS8PrivateKey(priv)
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if err != nil {
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return nil, nil, fmt.Errorf("GenerateOrLoadSSHKey: marshal key: %w", err)
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}
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keyPEM = pem.EncodeToMemory(&pem.Block{Type: "PRIVATE KEY", Bytes: keyDER})
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// Serialize public key as authorized_keys line.
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sshPub, err := ssh.NewPublicKey(pub)
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if err != nil {
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return nil, nil, fmt.Errorf("GenerateOrLoadSSHKey: new pubkey: %w", err)
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}
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pubLine = ssh.MarshalAuthorizedKey(sshPub)
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// Persist with correct modes (atomic write + chmod).
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if err := writeAtomic(keyPath, SSHKeyMode, keyPEM); err != nil {
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return nil, nil, fmt.Errorf("write SSH key: %w", err)
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}
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if err := writeAtomic(pubPath, SSHPubMode, pubLine); err != nil {
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return nil, nil, fmt.Errorf("write SSH pub: %w", err)
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}
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return keyPEM, pubLine, nil
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}
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