Merge branch 'morten/keyring'

* morten/keyring:
  agent: add SIGINT to the signal handler
  testdata: Include a test for askpass during signing
  scripts_test: set agent simulator to an underscore env
  agent: Integrate ThreadKeyring into the ssh agent
  keyring/threadkeyring: Implement a keyring pinned to the os thread
  keyring: add a keyctl implementation for keyrings
  keyring/key: implement a boxed byte slice for memory sensitive things
  agent: pass staticcheck

Signed-off-by: Morten Linderud <[email protected]>

agent/agent.go

@@ -18,6 +18,7 @@ import (
 	"log/slog"
 
 	keyfile "github.com/foxboron/go-tpm-keyfiles"
+	"github.com/foxboron/ssh-tpm-agent/internal/keyring"
 	"github.com/foxboron/ssh-tpm-agent/key"
 	"github.com/foxboron/ssh-tpm-agent/signer"
 	"github.com/google/go-tpm/tpm2/transport"
@@ -40,6 +41,7 @@ type Agent struct {
 	listener *net.UnixListener
 	quit     chan interface{}
 	wg       sync.WaitGroup
+	keyring  func() *keyring.ThreadKeyring
 	keys     []*key.SSHTPMKey
 	agents   []agent.ExtendedAgent
 }
@@ -106,7 +108,7 @@ func (a *Agent) signers() ([]ssh.Signer, error) {
 
 	for _, k := range a.keys {
 		s, err := ssh.NewSignerFromSigner(
-			signer.NewSSHKeySigner(k, a.op, a.tpm,
+			signer.NewSSHKeySigner(k, a.keyring(), a.op, a.tpm,
 				func(_ *keyfile.TPMKey) ([]byte, error) {
 					// Shimming the function to get the correct type
 					return a.pin(k)
@@ -432,7 +434,7 @@ func LoadKeys(keyDir string) ([]*key.SSHTPMKey, error) {
 	return keys, err
 }
 
-func NewAgent(listener *net.UnixListener, agents []agent.ExtendedAgent, tpmFetch func() transport.TPMCloser, ownerPassword func() ([]byte, error), pin func(*key.SSHTPMKey) ([]byte, error)) *Agent {
+func NewAgent(listener *net.UnixListener, agents []agent.ExtendedAgent, keyring func() *keyring.ThreadKeyring, tpmFetch func() transport.TPMCloser, ownerPassword func() ([]byte, error), pin func(*key.SSHTPMKey) ([]byte, error)) *Agent {
 	a := &Agent{
 		agents:   agents,
 		tpm:      tpmFetch,
@@ -441,6 +443,7 @@ func NewAgent(listener *net.UnixListener, agents []agent.ExtendedAgent, tpmFetch
 		pin:      pin,
 		quit:     make(chan interface{}),
 		keys:     []*key.SSHTPMKey{},
+		keyring:  keyring,
 	}
 
 	a.wg.Add(1)

agent/agent_test.go

@@ -11,6 +11,7 @@ import (
 	"testing"
 
 	"github.com/foxboron/ssh-tpm-agent/agent"
+	"github.com/foxboron/ssh-tpm-agent/internal/keyring"
 	"github.com/foxboron/ssh-tpm-agent/internal/keytest"
 	"github.com/foxboron/ssh-tpm-agent/key"
 	"github.com/google/go-tpm/tpm2"
@@ -37,6 +38,8 @@ func TestAddKey(t *testing.T) {
 
 	ag := agent.NewAgent(unixList,
 		[]sshagent.ExtendedAgent{},
+		// Keyring callback
+		func() *keyring.ThreadKeyring { return &keyring.ThreadKeyring{} },
 		// TPM Callback
 		func() transport.TPMCloser { return tpm },
 		// Owner password

agent/gocrypto.go

@@ -1,14 +1,5 @@
 package agent
 
-import (
-	"encoding/binary"
-	"fmt"
-
-	"golang.org/x/crypto/ssh"
-
-	sshagent "golang.org/x/crypto/ssh/agent"
-)
-
 // Code taken from crypto/x/ssh/agent
 
 const (
@@ -18,59 +9,58 @@ const (
 	// Constraint extension identifier up to version 2 of the protocol. A
 	// backward incompatible change will be required if we want to add support
 	// for SSH_AGENT_CONSTRAIN_MAXSIGN which uses the same ID.
-	agentConstrainExtensionV00 = 3
+	// agentConstrainExtensionV00 = 3
 	// Constraint extension identifier in version 3 and later of the protocol.
-	agentConstrainExtension = 255
+	// agentConstrainExtension = 255
 )
 
-type constrainExtensionAgentMsg struct {
-	ExtensionName    string `sshtype:"255|3"`
-	ExtensionDetails []byte
+// type constrainExtensionAgentMsg struct {
+// 	ExtensionName    string `sshtype:"255|3"`
+// 	ExtensionDetails []byte
 
-	// Rest is a field used for parsing, not part of message
-	Rest []byte `ssh:"rest"`
-}
+// 	// Rest is a field used for parsing, not part of message
+// 	Rest []byte `ssh:"rest"`
+// }
 
 // 3.7 Key constraint identifiers
 type constrainLifetimeAgentMsg struct {
 	LifetimeSecs uint32 `sshtype:"1"`
 }
 
-func parseConstraints(constraints []byte) (lifetimeSecs uint32, confirmBeforeUse bool, extensions []sshagent.ConstraintExtension, err error) {
-	for len(constraints) != 0 {
-		switch constraints[0] {
-		case agentConstrainLifetime:
-			lifetimeSecs = binary.BigEndian.Uint32(constraints[1:5])
-			constraints = constraints[5:]
-		case agentConstrainConfirm:
-			confirmBeforeUse = true
-			constraints = constraints[1:]
-		case agentConstrainExtension, agentConstrainExtensionV00:
-			var msg constrainExtensionAgentMsg
-			if err = ssh.Unmarshal(constraints, &msg); err != nil {
-				return 0, false, nil, err
-			}
-			extensions = append(extensions, sshagent.ConstraintExtension{
-				ExtensionName:    msg.ExtensionName,
-				ExtensionDetails: msg.ExtensionDetails,
-			})
-			constraints = msg.Rest
-		default:
-			return 0, false, nil, fmt.Errorf("unknown constraint type: %d", constraints[0])
-		}
-	}
-	return
-}
+// func parseConstraints(constraints []byte) (lifetimeSecs uint32, confirmBeforeUse bool, extensions []sshagent.ConstraintExtension, err error) {
+// 	for len(constraints) != 0 {
+// 		switch constraints[0] {
+// 		case agentConstrainLifetime:
+// 			lifetimeSecs = binary.BigEndian.Uint32(constraints[1:5])
+// 			constraints = constraints[5:]
+// 		case agentConstrainConfirm:
+// 			confirmBeforeUse = true
+// 			constraints = constraints[1:]
+// 		// case agentConstrainExtension, agentConstrainExtensionV00:
+// 		// 	var msg constrainExtensionAgentMsg
+// 		// 	if err = ssh.Unmarshal(constraints, &msg); err != nil {
+// 		// 		return 0, false, nil, err
+// 		// 	}
+// 		// 	extensions = append(extensions, sshagent.ConstraintExtension{
+// 		// 		ExtensionName:    msg.ExtensionName,
+// 		// 		ExtensionDetails: msg.ExtensionDetails,
+// 		// 	})
+// 		// 	constraints = msg.Rest
+// 		default:
+// 			return 0, false, nil, fmt.Errorf("unknown constraint type: %d", constraints[0])
+// 		}
+// 	}
+// 	return
+// }
 
-// TODO: Add constraints to our keys
 // func setConstraints(key *key.SSHTPMKey, constraintBytes []byte) error {
-// lifetimeSecs, confirmBeforeUse, constraintExtensions, err := parseConstraints(constraintBytes)
-// if err != nil {
-// 	return err
-// }
+// 	lifetimeSecs, confirmBeforeUse, constraintExtensions, err := parseConstraints(constraintBytes)
+// 	if err != nil {
+// 		return err
+// 	}
 
-// key.LifetimeSecs = lifetimeSecs
-// key.ConfirmBeforeUse = confirmBeforeUse
-// key.ConstraintExtensions = constraintExtensions
-// return nil
+// 	key.LifetimeSecs = lifetimeSecs
+// 	key.ConfirmBeforeUse = confirmBeforeUse
+// 	key.ConstraintExtensions = constraintExtensions
+// 	return nil
 // }

cmd/scripts_test.go

@@ -29,7 +29,7 @@ func ScriptsWithPath(t *testing.T, path string) {
 		Deadline: time.Now().Add(5 * time.Second),
 		Setup: func(e *testscript.Env) error {
 			e.Setenv("PATH", tmp+string(filepath.ListSeparator)+e.Getenv("PATH"))
-			e.Vars = append(e.Vars, "SSH_TPM_AGENT_SIMULATOR=1")
+			e.Vars = append(e.Vars, "_SSH_TPM_AGENT_SIMULATOR=1")
 			e.Vars = append(e.Vars, fmt.Sprintf("SSH_AUTH_SOCK=%s/agent.sock", e.WorkDir))
 			e.Vars = append(e.Vars, fmt.Sprintf("SSH_TPM_AUTH_SOCK=%s/agent.sock", e.WorkDir))
 			e.Vars = append(e.Vars, fmt.Sprintf("HOME=%s", e.WorkDir))

cmd/ssh-tpm-agent/main.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"context"
+	"errors"
 	"flag"
 	"fmt"
 	"log"
@@ -17,6 +19,7 @@ import (
 
 	"github.com/foxboron/ssh-tpm-agent/agent"
 	"github.com/foxboron/ssh-tpm-agent/askpass"
+	"github.com/foxboron/ssh-tpm-agent/internal/keyring"
 	"github.com/foxboron/ssh-tpm-agent/key"
 	"github.com/foxboron/ssh-tpm-agent/utils"
 	"github.com/google/go-tpm/tpm2/transport"
@@ -198,8 +201,22 @@ func main() {
 		os.Exit(1)
 	}
 
+	// TODO: Ensure the agent also uses thix context
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	agentkeyring, err := keyring.NewThreadKeyring(ctx, keyring.SessionKeyring)
+	if err != nil {
+		log.Fatal(err)
+	}
+
 	agent := agent.NewAgent(listener, agents,
 
+		// Keyring Callback
+		func() *keyring.ThreadKeyring {
+			return agentkeyring
+		},
+
 		// TPM Callback
 		func() (tpm transport.TPMCloser) {
 			// the agent will close the TPM after this is called
@@ -216,7 +233,6 @@ func main() {
 				return askpass.ReadPassphrase("Enter owner password for TPM", askpass.RP_USE_ASKPASS)
 			} else {
 				ownerPassword := os.Getenv("SSH_TPM_AGENT_OWNER_PASSWORD")
-
 				return []byte(ownerPassword), nil
 			}
 		},
@@ -225,23 +241,31 @@ func main() {
 		// SSHKeySigner in signer/signer.go resets this value if
 		// we get a TPMRCAuthFail
 		func(key *key.SSHTPMKey) ([]byte, error) {
-			if len(key.Userauth) != 0 {
-				slog.Debug("providing cached userauth for key", slog.String("desc", key.Description))
-				return key.Userauth, nil
-			}
-			keyInfo := fmt.Sprintf("Enter passphrase for (%s): ", key.Description)
-			userauth, err := askpass.ReadPassphrase(keyInfo, askpass.RP_USE_ASKPASS)
-			if !noCache && err == nil {
-				slog.Debug("caching userauth for key", slog.String("desc", key.Description))
-				key.Userauth = userauth
+			auth, err := agentkeyring.ReadKey(key.Fingerprint())
+			if err == nil {
+				slog.Debug("providing cached userauth for key", slog.String("fp", key.Fingerprint()))
+				// TODO: This is not great, but easier for now
+				return auth.Read(), nil
+			} else if errors.Is(err, syscall.ENOKEY) || errors.Is(err, syscall.EACCES) {
+				keyInfo := fmt.Sprintf("Enter passphrase for (%s): ", key.Description)
+				// TODOt kjk: askpass should box the byte slice
+				userauth, err := askpass.ReadPassphrase(keyInfo, askpass.RP_USE_ASKPASS)
+				if !noCache && err == nil {
+					slog.Debug("caching userauth for key in keyring", slog.String("fp", key.Fingerprint()))
+					if err := agentkeyring.AddKey(key.Fingerprint(), userauth); err != nil {
+						return nil, err
+					}
+				}
+				return userauth, err
 			}
-			return userauth, err
+			return nil, fmt.Errorf("failed getting pin for key: %w", err)
 		},
 	)
 
 	// Signal handling
 	c := make(chan os.Signal, 1)
 	signal.Notify(c, syscall.SIGHUP)
+	signal.Notify(c, syscall.SIGINT)
 	go func() {
 		for range c {
 			agent.Stop()

cmd/ssh-tpm-agent/main_test.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/foxboron/ssh-tpm-agent/agent"
+	"github.com/foxboron/ssh-tpm-agent/internal/keyring"
 	"github.com/foxboron/ssh-tpm-agent/internal/keytest"
 	"github.com/foxboron/ssh-tpm-agent/key"
 	"github.com/google/go-tpm/tpm2"
@@ -135,6 +136,8 @@ func runSSHAuth(t *testing.T, keytype tpm2.TPMAlgID, bits int, pin []byte, keyfn
 
 	ag := agent.NewAgent(unixList,
 		[]sshagent.ExtendedAgent{},
+		// Keyring  Callback
+		func() *keyring.ThreadKeyring { return &keyring.ThreadKeyring{} },
 		// TPM Callback
 		func() transport.TPMCloser { return tpm },
 		// Owner password

cmd/ssh-tpm-agent/testdata/script/agent_password.txt

@@ -0,0 +1,44 @@
+# Create an askpass binary
+exec go build -o askpass-test askpass.go
+exec ./askpass-test passphrase
+
+# Env
+env SSH_ASKPASS=./askpass-test
+env SSH_ASKPASS_REQUIRE=force
+
+# ssh sign file with password
+env _ASKPASS_PASSWORD=12345
+exec ssh-tpm-agent -d --no-load &agent&
+exec ssh-tpm-keygen -N $_ASKPASS_PASSWORD
+exec ssh-tpm-add
+stdout id_ecdsa.tpm
+exec ssh-add -l
+stdout ECDSA
+exec ssh-keygen -Y sign -n file -f .ssh/id_ecdsa.pub file_to_sign.txt
+stdin file_to_sign.txt
+exec ssh-keygen -Y check-novalidate -n file -f .ssh/id_ecdsa.pub -s file_to_sign.txt.sig
+exists file_to_sign.txt.sig
+exec ssh-add -D
+rm file_to_sign.txt.sig
+rm .ssh/id_ecdsa.tpm .ssh/id_ecdsa.pub
+
+-- file_to_sign.txt --
+Hello World
+
+-- go.mod --
+module example.com/askpass
+
+-- askpass.go --
+package main
+
+import (
+  "fmt"
+  "os"
+  "strings"
+)
+
+func main() {
+  if strings.Contains(os.Args[1], "passphrase") {
+	  fmt.Println(os.Getenv("_ASKPASS_PASSWORD"))
+  }
+}

go.mod

@@ -5,13 +5,14 @@ go 1.22.4
 toolchain go1.22.5
 
 require (
+	github.com/awnumar/memcall v0.4.0
 	github.com/foxboron/go-tpm-keyfiles v0.0.0-20240805214234-f870d6f1ff68
 	github.com/foxboron/ssh-tpm-ca-authority v0.0.0-20240806093457-88eeced81948
 	github.com/google/go-tpm v0.9.2-0.20240625170440-991b038b62b6
 	github.com/google/go-tpm-tools v0.4.4
 	github.com/rogpeppe/go-internal v1.13.1
 	golang.org/x/crypto v0.25.0
-	golang.org/x/sys v0.27.0
+	golang.org/x/sys v0.28.0
 	golang.org/x/term v0.26.0
 )
 

go.sum

@@ -1,3 +1,5 @@
+github.com/awnumar/memcall v0.4.0 h1:B7hgZYdfH6Ot1Goaz8jGne/7i8xD4taZie/PNSFZ29g=
+github.com/awnumar/memcall v0.4.0/go.mod h1:8xOx1YbfyuCg3Fy6TO8DK0kZUua3V42/goA5Ru47E8w=
 github.com/coreos/go-oidc/v3 v3.11.0 h1:Ia3MxdwpSw702YW0xgfmP1GVCMA9aEFWu12XUZ3/OtI=
 github.com/coreos/go-oidc/v3 v3.11.0/go.mod h1:gE3LgjOgFoHi9a4ce4/tJczr0Ai2/BoDhf0r5lltWI0=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -93,8 +95,8 @@ golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBc
 golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
-golang.org/x/sys v0.27.0 h1:wBqf8DvsY9Y/2P8gAfPDEYNuS30J4lPHJxXSb/nJZ+s=
-golang.org/x/sys v0.27.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/sys v0.28.0 h1:Fksou7UEQUWlKvIdsqzJmUmCX3cZuD2+P3XyyzwMhlA=
+golang.org/x/sys v0.28.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/term v0.5.0/go.mod h1:jMB1sMXY+tzblOD4FWmEbocvup2/aLOaQEp7JmGp78k=