fix subrepo break change

modules/crypto/ssh/agent/client.go

@@ -0,0 +1,615 @@
+// 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 agent implements a client to an ssh-agent daemon.
+
+References:
+  [PROTOCOL.agent]:    http://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/PROTOCOL.agent?rev=HEAD
+*/
+package agent // import "golang.org/x/crypto/ssh/agent"
+
+import (
+	"bytes"
+	"crypto/dsa"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rsa"
+	"encoding/base64"
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"io"
+	"math/big"
+	"sync"
+
+	"github.com/gogits/gogs/modules/crypto/ssh"
+)
+
+// Agent represents the capabilities of an ssh-agent.
+type Agent interface {
+	// List returns the identities known to the agent.
+	List() ([]*Key, error)
+
+	// Sign has the agent sign the data using a protocol 2 key as defined
+	// in [PROTOCOL.agent] section 2.6.2.
+	Sign(key ssh.PublicKey, data []byte) (*ssh.Signature, error)
+
+	// Add adds a private key to the agent.
+	Add(key AddedKey) error
+
+	// Remove removes all identities with the given public key.
+	Remove(key ssh.PublicKey) error
+
+	// RemoveAll removes all identities.
+	RemoveAll() error
+
+	// Lock locks the agent. Sign and Remove will fail, and List will empty an empty list.
+	Lock(passphrase []byte) error
+
+	// Unlock undoes the effect of Lock
+	Unlock(passphrase []byte) error
+
+	// Signers returns signers for all the known keys.
+	Signers() ([]ssh.Signer, error)
+}
+
+// AddedKey describes an SSH key to be added to an Agent.
+type AddedKey struct {
+	// PrivateKey must be a *rsa.PrivateKey, *dsa.PrivateKey or
+	// *ecdsa.PrivateKey, which will be inserted into the agent.
+	PrivateKey interface{}
+	// Certificate, if not nil, is communicated to the agent and will be
+	// stored with the key.
+	Certificate *ssh.Certificate
+	// Comment is an optional, free-form string.
+	Comment string
+	// LifetimeSecs, if not zero, is the number of seconds that the
+	// agent will store the key for.
+	LifetimeSecs uint32
+	// ConfirmBeforeUse, if true, requests that the agent confirm with the
+	// user before each use of this key.
+	ConfirmBeforeUse bool
+}
+
+// See [PROTOCOL.agent], section 3.
+const (
+	agentRequestV1Identities = 1
+
+	// 3.2 Requests from client to agent for protocol 2 key operations
+	agentAddIdentity         = 17
+	agentRemoveIdentity      = 18
+	agentRemoveAllIdentities = 19
+	agentAddIdConstrained    = 25
+
+	// 3.3 Key-type independent requests from client to agent
+	agentAddSmartcardKey            = 20
+	agentRemoveSmartcardKey         = 21
+	agentLock                       = 22
+	agentUnlock                     = 23
+	agentAddSmartcardKeyConstrained = 26
+
+	// 3.7 Key constraint identifiers
+	agentConstrainLifetime = 1
+	agentConstrainConfirm  = 2
+)
+
+// maxAgentResponseBytes is the maximum agent reply size that is accepted. This
+// is a sanity check, not a limit in the spec.
+const maxAgentResponseBytes = 16 << 20
+
+// Agent messages:
+// These structures mirror the wire format of the corresponding ssh agent
+// messages found in [PROTOCOL.agent].
+
+// 3.4 Generic replies from agent to client
+const agentFailure = 5
+
+type failureAgentMsg struct{}
+
+const agentSuccess = 6
+
+type successAgentMsg struct{}
+
+// See [PROTOCOL.agent], section 2.5.2.
+const agentRequestIdentities = 11
+
+type requestIdentitiesAgentMsg struct{}
+
+// See [PROTOCOL.agent], section 2.5.2.
+const agentIdentitiesAnswer = 12
+
+type identitiesAnswerAgentMsg struct {
+	NumKeys uint32 `sshtype:"12"`
+	Keys    []byte `ssh:"rest"`
+}
+
+// See [PROTOCOL.agent], section 2.6.2.
+const agentSignRequest = 13
+
+type signRequestAgentMsg struct {
+	KeyBlob []byte `sshtype:"13"`
+	Data    []byte
+	Flags   uint32
+}
+
+// See [PROTOCOL.agent], section 2.6.2.
+
+// 3.6 Replies from agent to client for protocol 2 key operations
+const agentSignResponse = 14
+
+type signResponseAgentMsg struct {
+	SigBlob []byte `sshtype:"14"`
+}
+
+type publicKey struct {
+	Format string
+	Rest   []byte `ssh:"rest"`
+}
+
+// Key represents a protocol 2 public key as defined in
+// [PROTOCOL.agent], section 2.5.2.
+type Key struct {
+	Format  string
+	Blob    []byte
+	Comment string
+}
+
+func clientErr(err error) error {
+	return fmt.Errorf("agent: client error: %v", err)
+}
+
+// String returns the storage form of an agent key with the format, base64
+// encoded serialized key, and the comment if it is not empty.
+func (k *Key) String() string {
+	s := string(k.Format) + " " + base64.StdEncoding.EncodeToString(k.Blob)
+
+	if k.Comment != "" {
+		s += " " + k.Comment
+	}
+
+	return s
+}
+
+// Type returns the public key type.
+func (k *Key) Type() string {
+	return k.Format
+}
+
+// Marshal returns key blob to satisfy the ssh.PublicKey interface.
+func (k *Key) Marshal() []byte {
+	return k.Blob
+}
+
+// Verify satisfies the ssh.PublicKey interface, but is not
+// implemented for agent keys.
+func (k *Key) Verify(data []byte, sig *ssh.Signature) error {
+	return errors.New("agent: agent key does not know how to verify")
+}
+
+type wireKey struct {
+	Format string
+	Rest   []byte `ssh:"rest"`
+}
+
+func parseKey(in []byte) (out *Key, rest []byte, err error) {
+	var record struct {
+		Blob    []byte
+		Comment string
+		Rest    []byte `ssh:"rest"`
+	}
+
+	if err := ssh.Unmarshal(in, &record); err != nil {
+		return nil, nil, err
+	}
+
+	var wk wireKey
+	if err := ssh.Unmarshal(record.Blob, &wk); err != nil {
+		return nil, nil, err
+	}
+
+	return &Key{
+		Format:  wk.Format,
+		Blob:    record.Blob,
+		Comment: record.Comment,
+	}, record.Rest, nil
+}
+
+// client is a client for an ssh-agent process.
+type client struct {
+	// conn is typically a *net.UnixConn
+	conn io.ReadWriter
+	// mu is used to prevent concurrent access to the agent
+	mu sync.Mutex
+}
+
+// NewClient returns an Agent that talks to an ssh-agent process over
+// the given connection.
+func NewClient(rw io.ReadWriter) Agent {
+	return &client{conn: rw}
+}
+
+// call sends an RPC to the agent. On success, the reply is
+// unmarshaled into reply and replyType is set to the first byte of
+// the reply, which contains the type of the message.
+func (c *client) call(req []byte) (reply interface{}, err error) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	msg := make([]byte, 4+len(req))
+	binary.BigEndian.PutUint32(msg, uint32(len(req)))
+	copy(msg[4:], req)
+	if _, err = c.conn.Write(msg); err != nil {
+		return nil, clientErr(err)
+	}
+
+	var respSizeBuf [4]byte
+	if _, err = io.ReadFull(c.conn, respSizeBuf[:]); err != nil {
+		return nil, clientErr(err)
+	}
+	respSize := binary.BigEndian.Uint32(respSizeBuf[:])
+	if respSize > maxAgentResponseBytes {
+		return nil, clientErr(err)
+	}
+
+	buf := make([]byte, respSize)
+	if _, err = io.ReadFull(c.conn, buf); err != nil {
+		return nil, clientErr(err)
+	}
+	reply, err = unmarshal(buf)
+	if err != nil {
+		return nil, clientErr(err)
+	}
+	return reply, err
+}
+
+func (c *client) simpleCall(req []byte) error {
+	resp, err := c.call(req)
+	if err != nil {
+		return err
+	}
+	if _, ok := resp.(*successAgentMsg); ok {
+		return nil
+	}
+	return errors.New("agent: failure")
+}
+
+func (c *client) RemoveAll() error {
+	return c.simpleCall([]byte{agentRemoveAllIdentities})
+}
+
+func (c *client) Remove(key ssh.PublicKey) error {
+	req := ssh.Marshal(&agentRemoveIdentityMsg{
+		KeyBlob: key.Marshal(),
+	})
+	return c.simpleCall(req)
+}
+
+func (c *client) Lock(passphrase []byte) error {
+	req := ssh.Marshal(&agentLockMsg{
+		Passphrase: passphrase,
+	})
+	return c.simpleCall(req)
+}
+
+func (c *client) Unlock(passphrase []byte) error {
+	req := ssh.Marshal(&agentUnlockMsg{
+		Passphrase: passphrase,
+	})
+	return c.simpleCall(req)
+}
+
+// List returns the identities known to the agent.
+func (c *client) List() ([]*Key, error) {
+	// see [PROTOCOL.agent] section 2.5.2.
+	req := []byte{agentRequestIdentities}
+
+	msg, err := c.call(req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch msg := msg.(type) {
+	case *identitiesAnswerAgentMsg:
+		if msg.NumKeys > maxAgentResponseBytes/8 {
+			return nil, errors.New("agent: too many keys in agent reply")
+		}
+		keys := make([]*Key, msg.NumKeys)
+		data := msg.Keys
+		for i := uint32(0); i < msg.NumKeys; i++ {
+			var key *Key
+			var err error
+			if key, data, err = parseKey(data); err != nil {
+				return nil, err
+			}
+			keys[i] = key
+		}
+		return keys, nil
+	case *failureAgentMsg:
+		return nil, errors.New("agent: failed to list keys")
+	}
+	panic("unreachable")
+}
+
+// Sign has the agent sign the data using a protocol 2 key as defined
+// in [PROTOCOL.agent] section 2.6.2.
+func (c *client) Sign(key ssh.PublicKey, data []byte) (*ssh.Signature, error) {
+	req := ssh.Marshal(signRequestAgentMsg{
+		KeyBlob: key.Marshal(),
+		Data:    data,
+	})
+
+	msg, err := c.call(req)
+	if err != nil {
+		return nil, err
+	}
+
+	switch msg := msg.(type) {
+	case *signResponseAgentMsg:
+		var sig ssh.Signature
+		if err := ssh.Unmarshal(msg.SigBlob, &sig); err != nil {
+			return nil, err
+		}
+
+		return &sig, nil
+	case *failureAgentMsg:
+		return nil, errors.New("agent: failed to sign challenge")
+	}
+	panic("unreachable")
+}
+
+// unmarshal parses an agent message in packet, returning the parsed
+// form and the message type of packet.
+func unmarshal(packet []byte) (interface{}, error) {
+	if len(packet) < 1 {
+		return nil, errors.New("agent: empty packet")
+	}
+	var msg interface{}
+	switch packet[0] {
+	case agentFailure:
+		return new(failureAgentMsg), nil
+	case agentSuccess:
+		return new(successAgentMsg), nil
+	case agentIdentitiesAnswer:
+		msg = new(identitiesAnswerAgentMsg)
+	case agentSignResponse:
+		msg = new(signResponseAgentMsg)
+	default:
+		return nil, fmt.Errorf("agent: unknown type tag %d", packet[0])
+	}
+	if err := ssh.Unmarshal(packet, msg); err != nil {
+		return nil, err
+	}
+	return msg, nil
+}
+
+type rsaKeyMsg struct {
+	Type        string `sshtype:"17"`
+	N           *big.Int
+	E           *big.Int
+	D           *big.Int
+	Iqmp        *big.Int // IQMP = Inverse Q Mod P
+	P           *big.Int
+	Q           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type dsaKeyMsg struct {
+	Type        string `sshtype:"17"`
+	P           *big.Int
+	Q           *big.Int
+	G           *big.Int
+	Y           *big.Int
+	X           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type ecdsaKeyMsg struct {
+	Type        string `sshtype:"17"`
+	Curve       string
+	KeyBytes    []byte
+	D           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+// Insert adds a private key to the agent.
+func (c *client) insertKey(s interface{}, comment string, constraints []byte) error {
+	var req []byte
+	switch k := s.(type) {
+	case *rsa.PrivateKey:
+		if len(k.Primes) != 2 {
+			return fmt.Errorf("agent: unsupported RSA key with %d primes", len(k.Primes))
+		}
+		k.Precompute()
+		req = ssh.Marshal(rsaKeyMsg{
+			Type:        ssh.KeyAlgoRSA,
+			N:           k.N,
+			E:           big.NewInt(int64(k.E)),
+			D:           k.D,
+			Iqmp:        k.Precomputed.Qinv,
+			P:           k.Primes[0],
+			Q:           k.Primes[1],
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *dsa.PrivateKey:
+		req = ssh.Marshal(dsaKeyMsg{
+			Type:        ssh.KeyAlgoDSA,
+			P:           k.P,
+			Q:           k.Q,
+			G:           k.G,
+			Y:           k.Y,
+			X:           k.X,
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *ecdsa.PrivateKey:
+		nistID := fmt.Sprintf("nistp%d", k.Params().BitSize)
+		req = ssh.Marshal(ecdsaKeyMsg{
+			Type:        "ecdsa-sha2-" + nistID,
+			Curve:       nistID,
+			KeyBytes:    elliptic.Marshal(k.Curve, k.X, k.Y),
+			D:           k.D,
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	default:
+		return fmt.Errorf("agent: unsupported key type %T", s)
+	}
+
+	// if constraints are present then the message type needs to be changed.
+	if len(constraints) != 0 {
+		req[0] = agentAddIdConstrained
+	}
+
+	resp, err := c.call(req)
+	if err != nil {
+		return err
+	}
+	if _, ok := resp.(*successAgentMsg); ok {
+		return nil
+	}
+	return errors.New("agent: failure")
+}
+
+type rsaCertMsg struct {
+	Type        string `sshtype:"17"`
+	CertBytes   []byte
+	D           *big.Int
+	Iqmp        *big.Int // IQMP = Inverse Q Mod P
+	P           *big.Int
+	Q           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type dsaCertMsg struct {
+	Type        string `sshtype:"17"`
+	CertBytes   []byte
+	X           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+type ecdsaCertMsg struct {
+	Type        string `sshtype:"17"`
+	CertBytes   []byte
+	D           *big.Int
+	Comments    string
+	Constraints []byte `ssh:"rest"`
+}
+
+// Insert adds a private key to the agent. If a certificate is given,
+// that certificate is added instead as public key.
+func (c *client) Add(key AddedKey) error {
+	var constraints []byte
+
+	if secs := key.LifetimeSecs; secs != 0 {
+		constraints = append(constraints, agentConstrainLifetime)
+
+		var secsBytes [4]byte
+		binary.BigEndian.PutUint32(secsBytes[:], secs)
+		constraints = append(constraints, secsBytes[:]...)
+	}
+
+	if key.ConfirmBeforeUse {
+		constraints = append(constraints, agentConstrainConfirm)
+	}
+
+	if cert := key.Certificate; cert == nil {
+		return c.insertKey(key.PrivateKey, key.Comment, constraints)
+	} else {
+		return c.insertCert(key.PrivateKey, cert, key.Comment, constraints)
+	}
+}
+
+func (c *client) insertCert(s interface{}, cert *ssh.Certificate, comment string, constraints []byte) error {
+	var req []byte
+	switch k := s.(type) {
+	case *rsa.PrivateKey:
+		if len(k.Primes) != 2 {
+			return fmt.Errorf("agent: unsupported RSA key with %d primes", len(k.Primes))
+		}
+		k.Precompute()
+		req = ssh.Marshal(rsaCertMsg{
+			Type:        cert.Type(),
+			CertBytes:   cert.Marshal(),
+			D:           k.D,
+			Iqmp:        k.Precomputed.Qinv,
+			P:           k.Primes[0],
+			Q:           k.Primes[1],
+			Comments:    comment,
+			Constraints: constraints,
+		})
+	case *dsa.PrivateKey:
+		req = ssh.Marshal(dsaCertMsg{
+			Type:      cert.Type(),
+			CertBytes: cert.Marshal(),
+			X:         k.X,
+			Comments:  comment,
+		})
+	case *ecdsa.PrivateKey:
+		req = ssh.Marshal(ecdsaCertMsg{
+			Type:      cert.Type(),
+			CertBytes: cert.Marshal(),
+			D:         k.D,
+			Comments:  comment,
+		})
+	default:
+		return fmt.Errorf("agent: unsupported key type %T", s)
+	}
+
+	// if constraints are present then the message type needs to be changed.
+	if len(constraints) != 0 {
+		req[0] = agentAddIdConstrained
+	}
+
+	signer, err := ssh.NewSignerFromKey(s)
+	if err != nil {
+		return err
+	}
+	if bytes.Compare(cert.Key.Marshal(), signer.PublicKey().Marshal()) != 0 {
+		return errors.New("agent: signer and cert have different public key")
+	}
+
+	resp, err := c.call(req)
+	if err != nil {
+		return err
+	}
+	if _, ok := resp.(*successAgentMsg); ok {
+		return nil
+	}
+	return errors.New("agent: failure")
+}
+
+// Signers provides a callback for client authentication.
+func (c *client) Signers() ([]ssh.Signer, error) {
+	keys, err := c.List()
+	if err != nil {
+		return nil, err
+	}
+
+	var result []ssh.Signer
+	for _, k := range keys {
+		result = append(result, &agentKeyringSigner{c, k})
+	}
+	return result, nil
+}
+
+type agentKeyringSigner struct {
+	agent *client
+	pub   ssh.PublicKey
+}
+
+func (s *agentKeyringSigner) PublicKey() ssh.PublicKey {
+	return s.pub
+}
+
+func (s *agentKeyringSigner) Sign(rand io.Reader, data []byte) (*ssh.Signature, error) {
+	// The agent has its own entropy source, so the rand argument is ignored.
+	return s.agent.Sign(s.pub, data)
+}