mirror of
https://codeberg.org/forgejo/forgejo.git
synced 2024-12-23 12:59:11 -05:00
628 lines
15 KiB
Go
Executable file
628 lines
15 KiB
Go
Executable file
// Copyright 2012 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package ssh
|
|
|
|
import (
|
|
"bytes"
|
|
"crypto"
|
|
"crypto/dsa"
|
|
"crypto/ecdsa"
|
|
"crypto/elliptic"
|
|
"crypto/rsa"
|
|
"crypto/x509"
|
|
"encoding/asn1"
|
|
"encoding/base64"
|
|
"encoding/pem"
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
"math/big"
|
|
)
|
|
|
|
// These constants represent the algorithm names for key types supported by this
|
|
// package.
|
|
const (
|
|
KeyAlgoRSA = "ssh-rsa"
|
|
KeyAlgoDSA = "ssh-dss"
|
|
KeyAlgoECDSA256 = "ecdsa-sha2-nistp256"
|
|
KeyAlgoECDSA384 = "ecdsa-sha2-nistp384"
|
|
KeyAlgoECDSA521 = "ecdsa-sha2-nistp521"
|
|
)
|
|
|
|
// parsePubKey parses a public key of the given algorithm.
|
|
// Use ParsePublicKey for keys with prepended algorithm.
|
|
func parsePubKey(in []byte, algo string) (pubKey PublicKey, rest []byte, err error) {
|
|
switch algo {
|
|
case KeyAlgoRSA:
|
|
return parseRSA(in)
|
|
case KeyAlgoDSA:
|
|
return parseDSA(in)
|
|
case KeyAlgoECDSA256, KeyAlgoECDSA384, KeyAlgoECDSA521:
|
|
return parseECDSA(in)
|
|
case CertAlgoRSAv01, CertAlgoDSAv01, CertAlgoECDSA256v01, CertAlgoECDSA384v01, CertAlgoECDSA521v01:
|
|
cert, err := parseCert(in, certToPrivAlgo(algo))
|
|
if err != nil {
|
|
return nil, nil, err
|
|
}
|
|
return cert, nil, nil
|
|
}
|
|
return nil, nil, fmt.Errorf("ssh: unknown key algorithm: %v", err)
|
|
}
|
|
|
|
// parseAuthorizedKey parses a public key in OpenSSH authorized_keys format
|
|
// (see sshd(8) manual page) once the options and key type fields have been
|
|
// removed.
|
|
func parseAuthorizedKey(in []byte) (out PublicKey, comment string, err error) {
|
|
in = bytes.TrimSpace(in)
|
|
|
|
i := bytes.IndexAny(in, " \t")
|
|
if i == -1 {
|
|
i = len(in)
|
|
}
|
|
base64Key := in[:i]
|
|
|
|
key := make([]byte, base64.StdEncoding.DecodedLen(len(base64Key)))
|
|
n, err := base64.StdEncoding.Decode(key, base64Key)
|
|
if err != nil {
|
|
return nil, "", err
|
|
}
|
|
key = key[:n]
|
|
out, err = ParsePublicKey(key)
|
|
if err != nil {
|
|
return nil, "", err
|
|
}
|
|
comment = string(bytes.TrimSpace(in[i:]))
|
|
return out, comment, nil
|
|
}
|
|
|
|
// ParseAuthorizedKeys parses a public key from an authorized_keys
|
|
// file used in OpenSSH according to the sshd(8) manual page.
|
|
func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error) {
|
|
for len(in) > 0 {
|
|
end := bytes.IndexByte(in, '\n')
|
|
if end != -1 {
|
|
rest = in[end+1:]
|
|
in = in[:end]
|
|
} else {
|
|
rest = nil
|
|
}
|
|
|
|
end = bytes.IndexByte(in, '\r')
|
|
if end != -1 {
|
|
in = in[:end]
|
|
}
|
|
|
|
in = bytes.TrimSpace(in)
|
|
if len(in) == 0 || in[0] == '#' {
|
|
in = rest
|
|
continue
|
|
}
|
|
|
|
i := bytes.IndexAny(in, " \t")
|
|
if i == -1 {
|
|
in = rest
|
|
continue
|
|
}
|
|
|
|
if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
|
|
return out, comment, options, rest, nil
|
|
}
|
|
|
|
// No key type recognised. Maybe there's an options field at
|
|
// the beginning.
|
|
var b byte
|
|
inQuote := false
|
|
var candidateOptions []string
|
|
optionStart := 0
|
|
for i, b = range in {
|
|
isEnd := !inQuote && (b == ' ' || b == '\t')
|
|
if (b == ',' && !inQuote) || isEnd {
|
|
if i-optionStart > 0 {
|
|
candidateOptions = append(candidateOptions, string(in[optionStart:i]))
|
|
}
|
|
optionStart = i + 1
|
|
}
|
|
if isEnd {
|
|
break
|
|
}
|
|
if b == '"' && (i == 0 || (i > 0 && in[i-1] != '\\')) {
|
|
inQuote = !inQuote
|
|
}
|
|
}
|
|
for i < len(in) && (in[i] == ' ' || in[i] == '\t') {
|
|
i++
|
|
}
|
|
if i == len(in) {
|
|
// Invalid line: unmatched quote
|
|
in = rest
|
|
continue
|
|
}
|
|
|
|
in = in[i:]
|
|
i = bytes.IndexAny(in, " \t")
|
|
if i == -1 {
|
|
in = rest
|
|
continue
|
|
}
|
|
|
|
if out, comment, err = parseAuthorizedKey(in[i:]); err == nil {
|
|
options = candidateOptions
|
|
return out, comment, options, rest, nil
|
|
}
|
|
|
|
in = rest
|
|
continue
|
|
}
|
|
|
|
return nil, "", nil, nil, errors.New("ssh: no key found")
|
|
}
|
|
|
|
// ParsePublicKey parses an SSH public key formatted for use in
|
|
// the SSH wire protocol according to RFC 4253, section 6.6.
|
|
func ParsePublicKey(in []byte) (out PublicKey, err error) {
|
|
algo, in, ok := parseString(in)
|
|
if !ok {
|
|
return nil, errShortRead
|
|
}
|
|
var rest []byte
|
|
out, rest, err = parsePubKey(in, string(algo))
|
|
if len(rest) > 0 {
|
|
return nil, errors.New("ssh: trailing junk in public key")
|
|
}
|
|
|
|
return out, err
|
|
}
|
|
|
|
// MarshalAuthorizedKey serializes key for inclusion in an OpenSSH
|
|
// authorized_keys file. The return value ends with newline.
|
|
func MarshalAuthorizedKey(key PublicKey) []byte {
|
|
b := &bytes.Buffer{}
|
|
b.WriteString(key.Type())
|
|
b.WriteByte(' ')
|
|
e := base64.NewEncoder(base64.StdEncoding, b)
|
|
e.Write(key.Marshal())
|
|
e.Close()
|
|
b.WriteByte('\n')
|
|
return b.Bytes()
|
|
}
|
|
|
|
// PublicKey is an abstraction of different types of public keys.
|
|
type PublicKey interface {
|
|
// Type returns the key's type, e.g. "ssh-rsa".
|
|
Type() string
|
|
|
|
// Marshal returns the serialized key data in SSH wire format,
|
|
// with the name prefix.
|
|
Marshal() []byte
|
|
|
|
// Verify that sig is a signature on the given data using this
|
|
// key. This function will hash the data appropriately first.
|
|
Verify(data []byte, sig *Signature) error
|
|
}
|
|
|
|
// A Signer can create signatures that verify against a public key.
|
|
type Signer interface {
|
|
// PublicKey returns an associated PublicKey instance.
|
|
PublicKey() PublicKey
|
|
|
|
// Sign returns raw signature for the given data. This method
|
|
// will apply the hash specified for the keytype to the data.
|
|
Sign(rand io.Reader, data []byte) (*Signature, error)
|
|
}
|
|
|
|
type rsaPublicKey rsa.PublicKey
|
|
|
|
func (r *rsaPublicKey) Type() string {
|
|
return "ssh-rsa"
|
|
}
|
|
|
|
// parseRSA parses an RSA key according to RFC 4253, section 6.6.
|
|
func parseRSA(in []byte) (out PublicKey, rest []byte, err error) {
|
|
var w struct {
|
|
E *big.Int
|
|
N *big.Int
|
|
Rest []byte `ssh:"rest"`
|
|
}
|
|
if err := Unmarshal(in, &w); err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
if w.E.BitLen() > 24 {
|
|
return nil, nil, errors.New("ssh: exponent too large")
|
|
}
|
|
e := w.E.Int64()
|
|
if e < 3 || e&1 == 0 {
|
|
return nil, nil, errors.New("ssh: incorrect exponent")
|
|
}
|
|
|
|
var key rsa.PublicKey
|
|
key.E = int(e)
|
|
key.N = w.N
|
|
return (*rsaPublicKey)(&key), w.Rest, nil
|
|
}
|
|
|
|
func (r *rsaPublicKey) Marshal() []byte {
|
|
e := new(big.Int).SetInt64(int64(r.E))
|
|
wirekey := struct {
|
|
Name string
|
|
E *big.Int
|
|
N *big.Int
|
|
}{
|
|
KeyAlgoRSA,
|
|
e,
|
|
r.N,
|
|
}
|
|
return Marshal(&wirekey)
|
|
}
|
|
|
|
func (r *rsaPublicKey) Verify(data []byte, sig *Signature) error {
|
|
if sig.Format != r.Type() {
|
|
return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, r.Type())
|
|
}
|
|
h := crypto.SHA1.New()
|
|
h.Write(data)
|
|
digest := h.Sum(nil)
|
|
return rsa.VerifyPKCS1v15((*rsa.PublicKey)(r), crypto.SHA1, digest, sig.Blob)
|
|
}
|
|
|
|
type rsaPrivateKey struct {
|
|
*rsa.PrivateKey
|
|
}
|
|
|
|
func (r *rsaPrivateKey) PublicKey() PublicKey {
|
|
return (*rsaPublicKey)(&r.PrivateKey.PublicKey)
|
|
}
|
|
|
|
func (r *rsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
|
|
h := crypto.SHA1.New()
|
|
h.Write(data)
|
|
digest := h.Sum(nil)
|
|
blob, err := rsa.SignPKCS1v15(rand, r.PrivateKey, crypto.SHA1, digest)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return &Signature{
|
|
Format: r.PublicKey().Type(),
|
|
Blob: blob,
|
|
}, nil
|
|
}
|
|
|
|
type dsaPublicKey dsa.PublicKey
|
|
|
|
func (r *dsaPublicKey) Type() string {
|
|
return "ssh-dss"
|
|
}
|
|
|
|
// parseDSA parses an DSA key according to RFC 4253, section 6.6.
|
|
func parseDSA(in []byte) (out PublicKey, rest []byte, err error) {
|
|
var w struct {
|
|
P, Q, G, Y *big.Int
|
|
Rest []byte `ssh:"rest"`
|
|
}
|
|
if err := Unmarshal(in, &w); err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
key := &dsaPublicKey{
|
|
Parameters: dsa.Parameters{
|
|
P: w.P,
|
|
Q: w.Q,
|
|
G: w.G,
|
|
},
|
|
Y: w.Y,
|
|
}
|
|
return key, w.Rest, nil
|
|
}
|
|
|
|
func (k *dsaPublicKey) Marshal() []byte {
|
|
w := struct {
|
|
Name string
|
|
P, Q, G, Y *big.Int
|
|
}{
|
|
k.Type(),
|
|
k.P,
|
|
k.Q,
|
|
k.G,
|
|
k.Y,
|
|
}
|
|
|
|
return Marshal(&w)
|
|
}
|
|
|
|
func (k *dsaPublicKey) Verify(data []byte, sig *Signature) error {
|
|
if sig.Format != k.Type() {
|
|
return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, k.Type())
|
|
}
|
|
h := crypto.SHA1.New()
|
|
h.Write(data)
|
|
digest := h.Sum(nil)
|
|
|
|
// Per RFC 4253, section 6.6,
|
|
// The value for 'dss_signature_blob' is encoded as a string containing
|
|
// r, followed by s (which are 160-bit integers, without lengths or
|
|
// padding, unsigned, and in network byte order).
|
|
// For DSS purposes, sig.Blob should be exactly 40 bytes in length.
|
|
if len(sig.Blob) != 40 {
|
|
return errors.New("ssh: DSA signature parse error")
|
|
}
|
|
r := new(big.Int).SetBytes(sig.Blob[:20])
|
|
s := new(big.Int).SetBytes(sig.Blob[20:])
|
|
if dsa.Verify((*dsa.PublicKey)(k), digest, r, s) {
|
|
return nil
|
|
}
|
|
return errors.New("ssh: signature did not verify")
|
|
}
|
|
|
|
type dsaPrivateKey struct {
|
|
*dsa.PrivateKey
|
|
}
|
|
|
|
func (k *dsaPrivateKey) PublicKey() PublicKey {
|
|
return (*dsaPublicKey)(&k.PrivateKey.PublicKey)
|
|
}
|
|
|
|
func (k *dsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
|
|
h := crypto.SHA1.New()
|
|
h.Write(data)
|
|
digest := h.Sum(nil)
|
|
r, s, err := dsa.Sign(rand, k.PrivateKey, digest)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
sig := make([]byte, 40)
|
|
rb := r.Bytes()
|
|
sb := s.Bytes()
|
|
|
|
copy(sig[20-len(rb):20], rb)
|
|
copy(sig[40-len(sb):], sb)
|
|
|
|
return &Signature{
|
|
Format: k.PublicKey().Type(),
|
|
Blob: sig,
|
|
}, nil
|
|
}
|
|
|
|
type ecdsaPublicKey ecdsa.PublicKey
|
|
|
|
func (key *ecdsaPublicKey) Type() string {
|
|
return "ecdsa-sha2-" + key.nistID()
|
|
}
|
|
|
|
func (key *ecdsaPublicKey) nistID() string {
|
|
switch key.Params().BitSize {
|
|
case 256:
|
|
return "nistp256"
|
|
case 384:
|
|
return "nistp384"
|
|
case 521:
|
|
return "nistp521"
|
|
}
|
|
panic("ssh: unsupported ecdsa key size")
|
|
}
|
|
|
|
func supportedEllipticCurve(curve elliptic.Curve) bool {
|
|
return curve == elliptic.P256() || curve == elliptic.P384() || curve == elliptic.P521()
|
|
}
|
|
|
|
// ecHash returns the hash to match the given elliptic curve, see RFC
|
|
// 5656, section 6.2.1
|
|
func ecHash(curve elliptic.Curve) crypto.Hash {
|
|
bitSize := curve.Params().BitSize
|
|
switch {
|
|
case bitSize <= 256:
|
|
return crypto.SHA256
|
|
case bitSize <= 384:
|
|
return crypto.SHA384
|
|
}
|
|
return crypto.SHA512
|
|
}
|
|
|
|
// parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
|
|
func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
|
|
var w struct {
|
|
Curve string
|
|
KeyBytes []byte
|
|
Rest []byte `ssh:"rest"`
|
|
}
|
|
|
|
if err := Unmarshal(in, &w); err != nil {
|
|
return nil, nil, err
|
|
}
|
|
|
|
key := new(ecdsa.PublicKey)
|
|
|
|
switch w.Curve {
|
|
case "nistp256":
|
|
key.Curve = elliptic.P256()
|
|
case "nistp384":
|
|
key.Curve = elliptic.P384()
|
|
case "nistp521":
|
|
key.Curve = elliptic.P521()
|
|
default:
|
|
return nil, nil, errors.New("ssh: unsupported curve")
|
|
}
|
|
|
|
key.X, key.Y = elliptic.Unmarshal(key.Curve, w.KeyBytes)
|
|
if key.X == nil || key.Y == nil {
|
|
return nil, nil, errors.New("ssh: invalid curve point")
|
|
}
|
|
return (*ecdsaPublicKey)(key), w.Rest, nil
|
|
}
|
|
|
|
func (key *ecdsaPublicKey) Marshal() []byte {
|
|
// See RFC 5656, section 3.1.
|
|
keyBytes := elliptic.Marshal(key.Curve, key.X, key.Y)
|
|
w := struct {
|
|
Name string
|
|
ID string
|
|
Key []byte
|
|
}{
|
|
key.Type(),
|
|
key.nistID(),
|
|
keyBytes,
|
|
}
|
|
|
|
return Marshal(&w)
|
|
}
|
|
|
|
func (key *ecdsaPublicKey) Verify(data []byte, sig *Signature) error {
|
|
if sig.Format != key.Type() {
|
|
return fmt.Errorf("ssh: signature type %s for key type %s", sig.Format, key.Type())
|
|
}
|
|
|
|
h := ecHash(key.Curve).New()
|
|
h.Write(data)
|
|
digest := h.Sum(nil)
|
|
|
|
// Per RFC 5656, section 3.1.2,
|
|
// The ecdsa_signature_blob value has the following specific encoding:
|
|
// mpint r
|
|
// mpint s
|
|
var ecSig struct {
|
|
R *big.Int
|
|
S *big.Int
|
|
}
|
|
|
|
if err := Unmarshal(sig.Blob, &ecSig); err != nil {
|
|
return err
|
|
}
|
|
|
|
if ecdsa.Verify((*ecdsa.PublicKey)(key), digest, ecSig.R, ecSig.S) {
|
|
return nil
|
|
}
|
|
return errors.New("ssh: signature did not verify")
|
|
}
|
|
|
|
type ecdsaPrivateKey struct {
|
|
*ecdsa.PrivateKey
|
|
}
|
|
|
|
func (k *ecdsaPrivateKey) PublicKey() PublicKey {
|
|
return (*ecdsaPublicKey)(&k.PrivateKey.PublicKey)
|
|
}
|
|
|
|
func (k *ecdsaPrivateKey) Sign(rand io.Reader, data []byte) (*Signature, error) {
|
|
h := ecHash(k.PrivateKey.PublicKey.Curve).New()
|
|
h.Write(data)
|
|
digest := h.Sum(nil)
|
|
r, s, err := ecdsa.Sign(rand, k.PrivateKey, digest)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
sig := make([]byte, intLength(r)+intLength(s))
|
|
rest := marshalInt(sig, r)
|
|
marshalInt(rest, s)
|
|
return &Signature{
|
|
Format: k.PublicKey().Type(),
|
|
Blob: sig,
|
|
}, nil
|
|
}
|
|
|
|
// NewSignerFromKey takes a pointer to rsa, dsa or ecdsa PrivateKey
|
|
// returns a corresponding Signer instance. EC keys should use P256,
|
|
// P384 or P521.
|
|
func NewSignerFromKey(k interface{}) (Signer, error) {
|
|
var sshKey Signer
|
|
switch t := k.(type) {
|
|
case *rsa.PrivateKey:
|
|
sshKey = &rsaPrivateKey{t}
|
|
case *dsa.PrivateKey:
|
|
sshKey = &dsaPrivateKey{t}
|
|
case *ecdsa.PrivateKey:
|
|
if !supportedEllipticCurve(t.Curve) {
|
|
return nil, errors.New("ssh: only P256, P384 and P521 EC keys are supported.")
|
|
}
|
|
|
|
sshKey = &ecdsaPrivateKey{t}
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %T", k)
|
|
}
|
|
return sshKey, nil
|
|
}
|
|
|
|
// NewPublicKey takes a pointer to rsa, dsa or ecdsa PublicKey
|
|
// and returns a corresponding ssh PublicKey instance. EC keys should use P256, P384 or P521.
|
|
func NewPublicKey(k interface{}) (PublicKey, error) {
|
|
var sshKey PublicKey
|
|
switch t := k.(type) {
|
|
case *rsa.PublicKey:
|
|
sshKey = (*rsaPublicKey)(t)
|
|
case *ecdsa.PublicKey:
|
|
if !supportedEllipticCurve(t.Curve) {
|
|
return nil, errors.New("ssh: only P256, P384 and P521 EC keys are supported.")
|
|
}
|
|
sshKey = (*ecdsaPublicKey)(t)
|
|
case *dsa.PublicKey:
|
|
sshKey = (*dsaPublicKey)(t)
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %T", k)
|
|
}
|
|
return sshKey, nil
|
|
}
|
|
|
|
// ParsePrivateKey returns a Signer from a PEM encoded private key. It supports
|
|
// the same keys as ParseRawPrivateKey.
|
|
func ParsePrivateKey(pemBytes []byte) (Signer, error) {
|
|
key, err := ParseRawPrivateKey(pemBytes)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return NewSignerFromKey(key)
|
|
}
|
|
|
|
// ParseRawPrivateKey returns a private key from a PEM encoded private key. It
|
|
// supports RSA (PKCS#1), DSA (OpenSSL), and ECDSA private keys.
|
|
func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
|
|
block, _ := pem.Decode(pemBytes)
|
|
if block == nil {
|
|
return nil, errors.New("ssh: no key found")
|
|
}
|
|
|
|
switch block.Type {
|
|
case "RSA PRIVATE KEY":
|
|
return x509.ParsePKCS1PrivateKey(block.Bytes)
|
|
case "EC PRIVATE KEY":
|
|
return x509.ParseECPrivateKey(block.Bytes)
|
|
case "DSA PRIVATE KEY":
|
|
return ParseDSAPrivateKey(block.Bytes)
|
|
default:
|
|
return nil, fmt.Errorf("ssh: unsupported key type %q", block.Type)
|
|
}
|
|
}
|
|
|
|
// ParseDSAPrivateKey returns a DSA private key from its ASN.1 DER encoding, as
|
|
// specified by the OpenSSL DSA man page.
|
|
func ParseDSAPrivateKey(der []byte) (*dsa.PrivateKey, error) {
|
|
var k struct {
|
|
Version int
|
|
P *big.Int
|
|
Q *big.Int
|
|
G *big.Int
|
|
Priv *big.Int
|
|
Pub *big.Int
|
|
}
|
|
rest, err := asn1.Unmarshal(der, &k)
|
|
if err != nil {
|
|
return nil, errors.New("ssh: failed to parse DSA key: " + err.Error())
|
|
}
|
|
if len(rest) > 0 {
|
|
return nil, errors.New("ssh: garbage after DSA key")
|
|
}
|
|
|
|
return &dsa.PrivateKey{
|
|
PublicKey: dsa.PublicKey{
|
|
Parameters: dsa.Parameters{
|
|
P: k.P,
|
|
Q: k.Q,
|
|
G: k.G,
|
|
},
|
|
Y: k.Priv,
|
|
},
|
|
X: k.Pub,
|
|
}, nil
|
|
}
|