Support for m.login.token (#2014)

* Add GOPATH to PATH in find-lint.sh.

The user doesn't necessarily have it in PATH.

* Refactor LoginTypePassword and Type to support m.login.token and m.login.sso.

For login token:

* m.login.token will require deleting the token after completeAuth has
  generated an access token, so a cleanup function is returned by
  Type.Login.
* Allowing different login types will require parsing the /login body
  twice: first to extract the "type" and then the type-specific parsing.
  Thus, we will have to buffer the request JSON in /login, like
  UserInteractive already does.

For SSO:

* NewUserInteractive will have to also use GetAccountByLocalpart. It
  makes more sense to just pass a (narrowed-down) accountDB interface
  to it than adding more function pointers.

Code quality:

* Passing around (and down-casting) interface{} for login request types
  has drawbacks in terms of type-safety, and no inherent benefits. We
  always decode JSON anyway. Hence renaming to Type.LoginFromJSON. Code
  that directly uses LoginTypePassword with parsed data can still use
  Login.
* Removed a TODO for SSO. This is already tracked in #1297.
* httputil.UnmarshalJSON is useful because it returns a JSONResponse.

This change is intended to have no functional changes.

* Support login tokens in User API.

This adds full lifecycle functions for login tokens: create, query, delete.

* Support m.login.token in /login.

* Fixes for PR review.

* Set @matrix-org/dendrite-core as repository code owner

* Return event NID from `StoreEvent`, match PSQL vs SQLite behaviour, tweak backfill persistence (#2071)

Co-authored-by: kegsay <kegan@matrix.org>
Co-authored-by: Neil Alexander <neilalexander@users.noreply.github.com>

build/scripts/find-lint.sh

@@ -33,7 +33,7 @@ echo "Looking for lint..."
 # Capture exit code to ensure go.{mod,sum} is restored before exiting
 exit_code=0
 
-golangci-lint run $args || exit_code=1
+PATH="$PATH:${GOPATH:-~/go}/bin" golangci-lint run $args || exit_code=1
 
 # Restore go.{mod,sum}
 mv go.mod.bak go.mod && mv go.sum.bak go.sum

clientapi/auth/auth.go

@@ -42,6 +42,7 @@ type DeviceDatabase interface {
 type AccountDatabase interface {
 	// Look up the account matching the given localpart.
 	GetAccountByLocalpart(ctx context.Context, localpart string) (*api.Account, error)
+	GetAccountByPassword(ctx context.Context, localpart, password string) (*api.Account, error)
 }
 
 // VerifyUserFromRequest authenticates the HTTP request,

clientapi/auth/authtypes/logintypes.go

@@ -10,4 +10,5 @@ const (
 	LoginTypeSharedSecret       = "org.matrix.login.shared_secret"
 	LoginTypeRecaptcha          = "m.login.recaptcha"
 	LoginTypeApplicationService = "m.login.application_service"
+	LoginTypeToken              = "m.login.token"
 )

clientapi/auth/login.go

@@ -0,0 +1,83 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package auth
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"io/ioutil"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/setup/config"
+	uapi "github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+)
+
+// LoginFromJSONReader performs authentication given a login request body reader and
+// some context. It returns the basic login information and a cleanup function to be
+// called after authorization has completed, with the result of the authorization.
+// If the final return value is non-nil, an error occurred and the cleanup function
+// is nil.
+func LoginFromJSONReader(ctx context.Context, r io.Reader, accountDB AccountDatabase, userAPI UserInternalAPIForLogin, cfg *config.ClientAPI) (*Login, LoginCleanupFunc, *util.JSONResponse) {
+	reqBytes, err := ioutil.ReadAll(r)
+	if err != nil {
+		err := &util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("Reading request body failed: " + err.Error()),
+		}
+		return nil, nil, err
+	}
+
+	var header struct {
+		Type string `json:"type"`
+	}
+	if err := json.Unmarshal(reqBytes, &header); err != nil {
+		err := &util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.BadJSON("Reading request body failed: " + err.Error()),
+		}
+		return nil, nil, err
+	}
+
+	var typ Type
+	switch header.Type {
+	case authtypes.LoginTypePassword:
+		typ = &LoginTypePassword{
+			GetAccountByPassword: accountDB.GetAccountByPassword,
+			Config:               cfg,
+		}
+	case authtypes.LoginTypeToken:
+		typ = &LoginTypeToken{
+			UserAPI: userAPI,
+			Config:  cfg,
+		}
+	default:
+		err := util.JSONResponse{
+			Code: http.StatusBadRequest,
+			JSON: jsonerror.InvalidArgumentValue("unhandled login type: " + header.Type),
+		}
+		return nil, nil, &err
+	}
+
+	return typ.LoginFromJSON(ctx, reqBytes)
+}
+
+// UserInternalAPIForLogin contains the aspects of UserAPI required for logging in.
+type UserInternalAPIForLogin interface {
+	uapi.LoginTokenInternalAPI
+}

clientapi/auth/login_test.go

@@ -0,0 +1,194 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package auth
+
+import (
+	"context"
+	"database/sql"
+	"net/http"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/setup/config"
+	uapi "github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+)
+
+func TestLoginFromJSONReader(t *testing.T) {
+	ctx := context.Background()
+
+	tsts := []struct {
+		Name string
+		Body string
+
+		WantUsername      string
+		WantDeviceID      string
+		WantDeletedTokens []string
+	}{
+		{
+			Name: "passwordWorks",
+			Body: `{
+				"type": "m.login.password",
+				"identifier": { "type": "m.id.user", "user": "alice" },
+				"password": "herpassword",
+				"device_id": "adevice"
+            }`,
+			WantUsername: "alice",
+			WantDeviceID: "adevice",
+		},
+		{
+			Name: "tokenWorks",
+			Body: `{
+				"type": "m.login.token",
+				"token": "atoken",
+				"device_id": "adevice"
+            }`,
+			WantUsername:      "@auser:example.com",
+			WantDeviceID:      "adevice",
+			WantDeletedTokens: []string{"atoken"},
+		},
+	}
+	for _, tst := range tsts {
+		t.Run(tst.Name, func(t *testing.T) {
+			var accountDB fakeAccountDB
+			var userAPI fakeUserInternalAPI
+			cfg := &config.ClientAPI{
+				Matrix: &config.Global{
+					ServerName: serverName,
+				},
+			}
+			login, cleanup, err := LoginFromJSONReader(ctx, strings.NewReader(tst.Body), &accountDB, &userAPI, cfg)
+			if err != nil {
+				t.Fatalf("LoginFromJSONReader failed: %+v", err)
+			}
+			cleanup(ctx, &util.JSONResponse{Code: http.StatusOK})
+
+			if login.Username() != tst.WantUsername {
+				t.Errorf("Username: got %q, want %q", login.Username(), tst.WantUsername)
+			}
+
+			if login.DeviceID == nil {
+				if tst.WantDeviceID != "" {
+					t.Errorf("DeviceID: got %v, want %q", login.DeviceID, tst.WantDeviceID)
+				}
+			} else {
+				if *login.DeviceID != tst.WantDeviceID {
+					t.Errorf("DeviceID: got %q, want %q", *login.DeviceID, tst.WantDeviceID)
+				}
+			}
+
+			if !reflect.DeepEqual(userAPI.DeletedTokens, tst.WantDeletedTokens) {
+				t.Errorf("DeletedTokens: got %+v, want %+v", userAPI.DeletedTokens, tst.WantDeletedTokens)
+			}
+		})
+	}
+}
+
+func TestBadLoginFromJSONReader(t *testing.T) {
+	ctx := context.Background()
+
+	tsts := []struct {
+		Name string
+		Body string
+
+		WantErrCode string
+	}{
+		{Name: "empty", WantErrCode: "M_BAD_JSON"},
+		{
+			Name:        "badUnmarshal",
+			Body:        `badsyntaxJSON`,
+			WantErrCode: "M_BAD_JSON",
+		},
+		{
+			Name: "badPassword",
+			Body: `{
+				"type": "m.login.password",
+				"identifier": { "type": "m.id.user", "user": "alice" },
+				"password": "invalidpassword",
+				"device_id": "adevice"
+            }`,
+			WantErrCode: "M_FORBIDDEN",
+		},
+		{
+			Name: "badToken",
+			Body: `{
+				"type": "m.login.token",
+				"token": "invalidtoken",
+				"device_id": "adevice"
+            }`,
+			WantErrCode: "M_FORBIDDEN",
+		},
+		{
+			Name: "badType",
+			Body: `{
+				"type": "m.login.invalid",
+				"device_id": "adevice"
+            }`,
+			WantErrCode: "M_INVALID_ARGUMENT_VALUE",
+		},
+	}
+	for _, tst := range tsts {
+		t.Run(tst.Name, func(t *testing.T) {
+			var accountDB fakeAccountDB
+			var userAPI fakeUserInternalAPI
+			cfg := &config.ClientAPI{
+				Matrix: &config.Global{
+					ServerName: serverName,
+				},
+			}
+			_, cleanup, errRes := LoginFromJSONReader(ctx, strings.NewReader(tst.Body), &accountDB, &userAPI, cfg)
+			if errRes == nil {
+				cleanup(ctx, nil)
+				t.Fatalf("LoginFromJSONReader err: got %+v, want code %q", errRes, tst.WantErrCode)
+			} else if merr, ok := errRes.JSON.(*jsonerror.MatrixError); ok && merr.ErrCode != tst.WantErrCode {
+				t.Fatalf("LoginFromJSONReader err: got %+v, want code %q", errRes, tst.WantErrCode)
+			}
+		})
+	}
+}
+
+type fakeAccountDB struct {
+	AccountDatabase
+}
+
+func (*fakeAccountDB) GetAccountByPassword(ctx context.Context, localpart, password string) (*uapi.Account, error) {
+	if password == "invalidpassword" {
+		return nil, sql.ErrNoRows
+	}
+
+	return &uapi.Account{}, nil
+}
+
+type fakeUserInternalAPI struct {
+	UserInternalAPIForLogin
+
+	DeletedTokens []string
+}
+
+func (ua *fakeUserInternalAPI) PerformLoginTokenDeletion(ctx context.Context, req *uapi.PerformLoginTokenDeletionRequest, res *uapi.PerformLoginTokenDeletionResponse) error {
+	ua.DeletedTokens = append(ua.DeletedTokens, req.Token)
+	return nil
+}
+
+func (*fakeUserInternalAPI) QueryLoginToken(ctx context.Context, req *uapi.QueryLoginTokenRequest, res *uapi.QueryLoginTokenResponse) error {
+	if req.Token == "invalidtoken" {
+		return nil
+	}
+
+	res.Data = &uapi.LoginTokenData{UserID: "@auser:example.com"}
+	return nil
+}

clientapi/auth/login_token.go

@@ -0,0 +1,83 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package auth
+
+import (
+	"context"
+	"net/http"
+
+	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
+	"github.com/matrix-org/dendrite/clientapi/httputil"
+	"github.com/matrix-org/dendrite/clientapi/jsonerror"
+	"github.com/matrix-org/dendrite/setup/config"
+	uapi "github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+)
+
+// LoginTypeToken describes how to authenticate with a login token.
+type LoginTypeToken struct {
+	UserAPI uapi.LoginTokenInternalAPI
+	Config  *config.ClientAPI
+}
+
+// Name implements Type.
+func (t *LoginTypeToken) Name() string {
+	return authtypes.LoginTypeToken
+}
+
+// LoginFromJSON implements Type. The cleanup function deletes the token from
+// the database on success.
+func (t *LoginTypeToken) LoginFromJSON(ctx context.Context, reqBytes []byte) (*Login, LoginCleanupFunc, *util.JSONResponse) {
+	var r loginTokenRequest
+	if err := httputil.UnmarshalJSON(reqBytes, &r); err != nil {
+		return nil, nil, err
+	}
+
+	var res uapi.QueryLoginTokenResponse
+	if err := t.UserAPI.QueryLoginToken(ctx, &uapi.QueryLoginTokenRequest{Token: r.Token}, &res); err != nil {
+		util.GetLogger(ctx).WithError(err).Error("UserAPI.QueryLoginToken failed")
+		jsonErr := jsonerror.InternalServerError()
+		return nil, nil, &jsonErr
+	}
+	if res.Data == nil {
+		return nil, nil, &util.JSONResponse{
+			Code: http.StatusForbidden,
+			JSON: jsonerror.Forbidden("invalid login token"),
+		}
+	}
+
+	r.Login.Identifier.Type = "m.id.user"
+	r.Login.Identifier.User = res.Data.UserID
+
+	cleanup := func(ctx context.Context, authRes *util.JSONResponse) {
+		if authRes == nil {
+			util.GetLogger(ctx).Error("No JSONResponse provided to LoginTokenType cleanup function")
+			return
+		}
+		if authRes.Code == http.StatusOK {
+			var res uapi.PerformLoginTokenDeletionResponse
+			if err := t.UserAPI.PerformLoginTokenDeletion(ctx, &uapi.PerformLoginTokenDeletionRequest{Token: r.Token}, &res); err != nil {
+				util.GetLogger(ctx).WithError(err).Error("UserAPI.PerformLoginTokenDeletion failed")
+			}
+		}
+	}
+	return &r.Login, cleanup, nil
+}
+
+// loginTokenRequest struct to hold the possible parameters from an HTTP request.
+type loginTokenRequest struct {
+	Login
+	Token string `json:"token"`
+}

clientapi/auth/password.go

@@ -20,6 +20,8 @@ import (
 	"net/http"
 	"strings"
 
+	"github.com/matrix-org/dendrite/clientapi/auth/authtypes"
+	"github.com/matrix-org/dendrite/clientapi/httputil"
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/dendrite/clientapi/userutil"
 	"github.com/matrix-org/dendrite/setup/config"
@@ -41,16 +43,26 @@ type LoginTypePassword struct {
 }
 
 func (t *LoginTypePassword) Name() string {
-	return "m.login.password"
+	return authtypes.LoginTypePassword
 }
 
-func (t *LoginTypePassword) Request() interface{} {
+func (t *LoginTypePassword) LoginFromJSON(ctx context.Context, reqBytes []byte) (*Login, LoginCleanupFunc, *util.JSONResponse) {
-	return &PasswordRequest{}
+	var r PasswordRequest
+	if err := httputil.UnmarshalJSON(reqBytes, &r); err != nil {
+		return nil, nil, err
+	}
+
+	login, err := t.Login(ctx, &r)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	return login, func(context.Context, *util.JSONResponse) {}, nil
 }
 
 func (t *LoginTypePassword) Login(ctx context.Context, req interface{}) (*Login, *util.JSONResponse) {
 	r := req.(*PasswordRequest)
-	username := r.Username()
+  username := strings.ToLower(r.Username())
 	if username == "" {
 		return nil, &util.JSONResponse{
 			Code: http.StatusUnauthorized,

clientapi/auth/user_interactive.go

@@ -32,22 +32,24 @@ import (
 type Type interface {
 	// Name returns the name of the auth type e.g `m.login.password`
 	Name() string
-	// Request returns a pointer to a new request body struct to unmarshal into.
-	Request() interface{}
 	// Login with the auth type, returning an error response on failure.
 	// Not all types support login, only m.login.password and m.login.token
 	// See https://matrix.org/docs/spec/client_server/r0.6.1#post-matrix-client-r0-login
-	// `req` is guaranteed to be the type returned from Request()
 	// This function will be called when doing login and when doing 'sudo' style
 	// actions e.g deleting devices. The response must be a 401 as per:
 	// "If the homeserver decides that an attempt on a stage was unsuccessful, but the
 	// client may make a second attempt, it returns the same HTTP status 401 response as above,
 	// with the addition of the standard errcode and error fields describing the error."
-	Login(ctx context.Context, req interface{}) (login *Login, errRes *util.JSONResponse)
+	//
+	// The returned cleanup function must be non-nil on success, and will be called after
+	// authorization has been completed. Its argument is the final result of authorization.
+	LoginFromJSON(ctx context.Context, reqBytes []byte) (login *Login, cleanup LoginCleanupFunc, errRes *util.JSONResponse)
 	// TODO: Extend to support Register() flow
 	// Register(ctx context.Context, sessionID string, req interface{})
 }
 
+type LoginCleanupFunc func(context.Context, *util.JSONResponse)
+
 // LoginIdentifier represents identifier types
 // https://matrix.org/docs/spec/client_server/r0.6.1#identifier-types
 type LoginIdentifier struct {
@@ -61,11 +63,8 @@ type LoginIdentifier struct {
 
 // Login represents the shared fields used in all forms of login/sudo endpoints.
 type Login struct {
-	Type       string          `json:"type"`
+	LoginIdentifier                 // Flat fields deprecated in favour of `identifier`.
-	Identifier LoginIdentifier `json:"identifier"`
+	Identifier      LoginIdentifier `json:"identifier"`
-	User       string          `json:"user"`    // deprecated in favour of identifier
-	Medium     string          `json:"medium"`  // deprecated in favour of identifier
-	Address    string          `json:"address"` // deprecated in favour of identifier
 
 	// Both DeviceID and InitialDisplayName can be omitted, or empty strings ("")
 	// Thus a pointer is needed to differentiate between the two
@@ -111,12 +110,11 @@ type UserInteractive struct {
 	Sessions map[string][]string
 }
 
-func NewUserInteractive(getAccByPass GetAccountByPassword, cfg *config.ClientAPI) *UserInteractive {
+func NewUserInteractive(accountDB AccountDatabase, cfg *config.ClientAPI) *UserInteractive {
 	typePassword := &LoginTypePassword{
-		GetAccountByPassword: getAccByPass,
+		GetAccountByPassword: accountDB.GetAccountByPassword,
 		Config:               cfg,
 	}
-	// TODO: Add SSO login
 	return &UserInteractive{
 		Completed: []string{},
 		Flows: []userInteractiveFlow{
@@ -236,18 +234,13 @@ func (u *UserInteractive) Verify(ctx context.Context, bodyBytes []byte, device *
 		}
 	}
 
-	r := loginType.Request()
+	login, cleanup, resErr := loginType.LoginFromJSON(ctx, []byte(gjson.GetBytes(bodyBytes, "auth").Raw))
-	if err := json.Unmarshal([]byte(gjson.GetBytes(bodyBytes, "auth").Raw), r); err != nil {
+	if resErr != nil {
-		return nil, &util.JSONResponse{
+		return nil, u.ResponseWithChallenge(sessionID, resErr.JSON)
-			Code: http.StatusBadRequest,
-			JSON: jsonerror.BadJSON("The request body could not be decoded into valid JSON. " + err.Error()),
-		}
 	}
-	login, resErr := loginType.Login(ctx, r)
+
-	if resErr == nil {
+	u.AddCompletedStage(sessionID, authType)
-		u.AddCompletedStage(sessionID, authType)
+	cleanup(ctx, nil)
-		// TODO: Check if there's more stages to go and return an error
+	// TODO: Check if there's more stages to go and return an error
-		return login, nil
+	return login, nil
-	}
-	return nil, u.ResponseWithChallenge(sessionID, resErr.JSON)
 }

clientapi/auth/user_interactive_test.go

@@ -24,7 +24,11 @@ var (
 	}
 )
 
-func getAccountByPassword(ctx context.Context, localpart, plaintextPassword string) (*api.Account, error) {
+type fakeAccountDatabase struct {
+	AccountDatabase
+}
+
+func (*fakeAccountDatabase) GetAccountByPassword(ctx context.Context, localpart, plaintextPassword string) (*api.Account, error) {
 	acc, ok := lookup[localpart+" "+plaintextPassword]
 	if !ok {
 		return nil, fmt.Errorf("unknown user/password")
@@ -38,7 +42,7 @@ func setup() *UserInteractive {
 			ServerName: serverName,
 		},
 	}
-	return NewUserInteractive(getAccountByPassword, cfg)
+	return NewUserInteractive(&fakeAccountDatabase{}, cfg)
 }
 
 func TestUserInteractiveChallenge(t *testing.T) {

clientapi/httputil/httputil.go

@@ -36,6 +36,10 @@ func UnmarshalJSONRequest(req *http.Request, iface interface{}) *util.JSONRespon
 		return &resp
 	}
 
+	return UnmarshalJSON(body, iface)
+}
+
+func UnmarshalJSON(body []byte, iface interface{}) *util.JSONResponse {
 	if !utf8.Valid(body) {
 		return &util.JSONResponse{
 			Code: http.StatusBadRequest,

clientapi/routing/login.go

@@ -19,7 +19,6 @@ import (
 	"net/http"
 
 	"github.com/matrix-org/dendrite/clientapi/auth"
-	"github.com/matrix-org/dendrite/clientapi/httputil"
 	"github.com/matrix-org/dendrite/clientapi/jsonerror"
 	"github.com/matrix-org/dendrite/clientapi/userutil"
 	"github.com/matrix-org/dendrite/setup/config"
@@ -65,21 +64,14 @@ func Login(
 			JSON: passwordLogin(),
 		}
 	} else if req.Method == http.MethodPost {
-		typePassword := auth.LoginTypePassword{
+		login, cleanup, authErr := auth.LoginFromJSONReader(req.Context(), req.Body, accountDB, userAPI, cfg)
-			GetAccountByPassword: accountDB.GetAccountByPassword,
-			Config:               cfg,
-		}
-		r := typePassword.Request()
-		resErr := httputil.UnmarshalJSONRequest(req, r)
-		if resErr != nil {
-			return *resErr
-		}
-		login, authErr := typePassword.Login(req.Context(), r)
 		if authErr != nil {
 			return *authErr
 		}
 		// make a device/access token
-		return completeAuth(req.Context(), cfg.Matrix.ServerName, userAPI, login, req.RemoteAddr, req.UserAgent())
+		authErr2 := completeAuth(req.Context(), cfg.Matrix.ServerName, userAPI, login, req.RemoteAddr, req.UserAgent())
+		cleanup(req.Context(), &authErr2)
+		return authErr2
 	}
 	return util.JSONResponse{
 		Code: http.StatusMethodNotAllowed,

clientapi/routing/routing.go

@@ -62,7 +62,7 @@ func Setup(
 	mscCfg *config.MSCs,
 ) {
 	rateLimits := httputil.NewRateLimits(&cfg.RateLimiting)
-	userInteractiveAuth := auth.NewUserInteractive(accountDB.GetAccountByPassword, cfg)
+	userInteractiveAuth := auth.NewUserInteractive(accountDB, cfg)
 
 	unstableFeatures := map[string]bool{
 		"org.matrix.e2e_cross_signing": true,

userapi/api/api.go

@@ -24,6 +24,8 @@ import (
 
 // UserInternalAPI is the internal API for information about users and devices.
 type UserInternalAPI interface {
+	LoginTokenInternalAPI
+
 	InputAccountData(ctx context.Context, req *InputAccountDataRequest, res *InputAccountDataResponse) error
 	PerformAccountCreation(ctx context.Context, req *PerformAccountCreationRequest, res *PerformAccountCreationResponse) error
 	PerformPasswordUpdate(ctx context.Context, req *PerformPasswordUpdateRequest, res *PerformPasswordUpdateResponse) error

userapi/api/api_logintoken.go

@@ -0,0 +1,69 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package api
+
+import (
+	"context"
+	"time"
+)
+
+type LoginTokenInternalAPI interface {
+	// PerformLoginTokenCreation creates a new login token and associates it with the provided data.
+	PerformLoginTokenCreation(ctx context.Context, req *PerformLoginTokenCreationRequest, res *PerformLoginTokenCreationResponse) error
+
+	// PerformLoginTokenDeletion ensures the token doesn't exist. Success
+	// is returned even if the token didn't exist, or was already deleted.
+	PerformLoginTokenDeletion(ctx context.Context, req *PerformLoginTokenDeletionRequest, res *PerformLoginTokenDeletionResponse) error
+
+	// QueryLoginToken returns the data associated with a login token. If
+	// the token is not valid, success is returned, but res.Data == nil.
+	QueryLoginToken(ctx context.Context, req *QueryLoginTokenRequest, res *QueryLoginTokenResponse) error
+}
+
+// LoginTokenData is the data that can be retrieved given a login token. This is
+// provided by the calling code.
+type LoginTokenData struct {
+	// UserID is the full mxid of the user.
+	UserID string
+}
+
+// LoginTokenMetadata contains metadata created and maintained by the User API.
+type LoginTokenMetadata struct {
+	Token      string
+	Expiration time.Time
+}
+
+type PerformLoginTokenCreationRequest struct {
+	Data LoginTokenData
+}
+
+type PerformLoginTokenCreationResponse struct {
+	Metadata LoginTokenMetadata
+}
+
+type PerformLoginTokenDeletionRequest struct {
+	Token string
+}
+
+type PerformLoginTokenDeletionResponse struct{}
+
+type QueryLoginTokenRequest struct {
+	Token string
+}
+
+type QueryLoginTokenResponse struct {
+	// Data is nil if the token was invalid.
+	Data *LoginTokenData
+}

userapi/api/api_trace_logintoken.go

@@ -0,0 +1,39 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package api
+
+import (
+	"context"
+
+	"github.com/matrix-org/util"
+)
+
+func (t *UserInternalAPITrace) PerformLoginTokenCreation(ctx context.Context, req *PerformLoginTokenCreationRequest, res *PerformLoginTokenCreationResponse) error {
+	err := t.Impl.PerformLoginTokenCreation(ctx, req, res)
+	util.GetLogger(ctx).Infof("PerformLoginTokenCreation req=%+v res=%+v", js(req), js(res))
+	return err
+}
+
+func (t *UserInternalAPITrace) PerformLoginTokenDeletion(ctx context.Context, req *PerformLoginTokenDeletionRequest, res *PerformLoginTokenDeletionResponse) error {
+	err := t.Impl.PerformLoginTokenDeletion(ctx, req, res)
+	util.GetLogger(ctx).Infof("PerformLoginTokenDeletion req=%+v res=%+v", js(req), js(res))
+	return err
+}
+
+func (t *UserInternalAPITrace) QueryLoginToken(ctx context.Context, req *QueryLoginTokenRequest, res *QueryLoginTokenResponse) error {
+	err := t.Impl.QueryLoginToken(ctx, req, res)
+	util.GetLogger(ctx).Infof("QueryLoginToken req=%+v res=%+v", js(req), js(res))
+	return err
+}

userapi/internal/api_logintoken.go

@@ -0,0 +1,78 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/gomatrixserverlib"
+	"github.com/matrix-org/util"
+)
+
+// PerformLoginTokenCreation creates a new login token and associates it with the provided data.
+func (a *UserInternalAPI) PerformLoginTokenCreation(ctx context.Context, req *api.PerformLoginTokenCreationRequest, res *api.PerformLoginTokenCreationResponse) error {
+	util.GetLogger(ctx).WithField("user_id", req.Data.UserID).Info("PerformLoginTokenCreation")
+	_, domain, err := gomatrixserverlib.SplitID('@', req.Data.UserID)
+	if err != nil {
+		return err
+	}
+	if domain != a.ServerName {
+		return fmt.Errorf("cannot create a login token for a remote user: got %s want %s", domain, a.ServerName)
+	}
+	tokenMeta, err := a.DeviceDB.CreateLoginToken(ctx, &req.Data)
+	if err != nil {
+		return err
+	}
+	res.Metadata = *tokenMeta
+	return nil
+}
+
+// PerformLoginTokenDeletion ensures the token doesn't exist.
+func (a *UserInternalAPI) PerformLoginTokenDeletion(ctx context.Context, req *api.PerformLoginTokenDeletionRequest, res *api.PerformLoginTokenDeletionResponse) error {
+	util.GetLogger(ctx).Info("PerformLoginTokenDeletion")
+	return a.DeviceDB.RemoveLoginToken(ctx, req.Token)
+}
+
+// QueryLoginToken returns the data associated with a login token. If
+// the token is not valid, success is returned, but res.Data == nil.
+func (a *UserInternalAPI) QueryLoginToken(ctx context.Context, req *api.QueryLoginTokenRequest, res *api.QueryLoginTokenResponse) error {
+	tokenData, err := a.DeviceDB.GetLoginTokenDataByToken(ctx, req.Token)
+	if err != nil {
+		res.Data = nil
+		if err == sql.ErrNoRows {
+			return nil
+		}
+		return err
+	}
+	localpart, domain, err := gomatrixserverlib.SplitID('@', tokenData.UserID)
+	if err != nil {
+		return err
+	}
+	if domain != a.ServerName {
+		return fmt.Errorf("cannot return a login token for a remote user: got %s want %s", domain, a.ServerName)
+	}
+	if _, err := a.AccountDB.GetAccountByLocalpart(ctx, localpart); err != nil {
+		res.Data = nil
+		if err == sql.ErrNoRows {
+			return nil
+		}
+		return err
+	}
+	res.Data = tokenData
+	return nil
+}

userapi/inthttp/client_logintoken.go

@@ -0,0 +1,65 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package inthttp
+
+import (
+	"context"
+
+	"github.com/matrix-org/dendrite/internal/httputil"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/opentracing/opentracing-go"
+)
+
+const (
+	PerformLoginTokenCreationPath = "/userapi/performLoginTokenCreation"
+	PerformLoginTokenDeletionPath = "/userapi/performLoginTokenDeletion"
+	QueryLoginTokenPath           = "/userapi/queryLoginToken"
+)
+
+func (h *httpUserInternalAPI) PerformLoginTokenCreation(
+	ctx context.Context,
+	request *api.PerformLoginTokenCreationRequest,
+	response *api.PerformLoginTokenCreationResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "PerformLoginTokenCreation")
+	defer span.Finish()
+
+	apiURL := h.apiURL + PerformLoginTokenCreationPath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}
+
+func (h *httpUserInternalAPI) PerformLoginTokenDeletion(
+	ctx context.Context,
+	request *api.PerformLoginTokenDeletionRequest,
+	response *api.PerformLoginTokenDeletionResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "PerformLoginTokenDeletion")
+	defer span.Finish()
+
+	apiURL := h.apiURL + PerformLoginTokenDeletionPath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}
+
+func (h *httpUserInternalAPI) QueryLoginToken(
+	ctx context.Context,
+	request *api.QueryLoginTokenRequest,
+	response *api.QueryLoginTokenResponse,
+) error {
+	span, ctx := opentracing.StartSpanFromContext(ctx, "QueryLoginToken")
+	defer span.Finish()
+
+	apiURL := h.apiURL + QueryLoginTokenPath
+	return httputil.PostJSON(ctx, span, h.httpClient, apiURL, request, response)
+}

userapi/inthttp/server.go

@@ -27,6 +27,8 @@ import (
 
 // nolint: gocyclo
 func AddRoutes(internalAPIMux *mux.Router, s api.UserInternalAPI) {
+	addRoutesLoginToken(internalAPIMux, s)
+
 	internalAPIMux.Handle(PerformAccountCreationPath,
 		httputil.MakeInternalAPI("performAccountCreation", func(req *http.Request) util.JSONResponse {
 			request := api.PerformAccountCreationRequest{}

userapi/inthttp/server_logintoken.go

@@ -0,0 +1,68 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package inthttp
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/gorilla/mux"
+	"github.com/matrix-org/dendrite/internal/httputil"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+)
+
+// addRoutesLoginToken adds routes for all login token API calls.
+func addRoutesLoginToken(internalAPIMux *mux.Router, s api.UserInternalAPI) {
+	internalAPIMux.Handle(PerformLoginTokenCreationPath,
+		httputil.MakeInternalAPI("performLoginTokenCreation", func(req *http.Request) util.JSONResponse {
+			request := api.PerformLoginTokenCreationRequest{}
+			response := api.PerformLoginTokenCreationResponse{}
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := s.PerformLoginTokenCreation(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
+	internalAPIMux.Handle(PerformLoginTokenDeletionPath,
+		httputil.MakeInternalAPI("performLoginTokenDeletion", func(req *http.Request) util.JSONResponse {
+			request := api.PerformLoginTokenDeletionRequest{}
+			response := api.PerformLoginTokenDeletionResponse{}
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := s.PerformLoginTokenDeletion(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
+	internalAPIMux.Handle(QueryLoginTokenPath,
+		httputil.MakeInternalAPI("queryLoginToken", func(req *http.Request) util.JSONResponse {
+			request := api.QueryLoginTokenRequest{}
+			response := api.QueryLoginTokenResponse{}
+			if err := json.NewDecoder(req.Body).Decode(&request); err != nil {
+				return util.MessageResponse(http.StatusBadRequest, err.Error())
+			}
+			if err := s.QueryLoginToken(req.Context(), &request, &response); err != nil {
+				return util.ErrorResponse(err)
+			}
+			return util.JSONResponse{Code: http.StatusOK, JSON: &response}
+		}),
+	)
+}

userapi/storage/devices/interface.go

@@ -38,4 +38,15 @@ type Database interface {
 	RemoveDevices(ctx context.Context, localpart string, devices []string) error
 	// RemoveAllDevices deleted all devices for this user. Returns the devices deleted.
 	RemoveAllDevices(ctx context.Context, localpart, exceptDeviceID string) (devices []api.Device, err error)
+
+	// CreateLoginToken generates a token, stores and returns it. The lifetime is
+	// determined by the loginTokenLifetime given to the Database constructor.
+	CreateLoginToken(ctx context.Context, data *api.LoginTokenData) (*api.LoginTokenMetadata, error)
+
+	// RemoveLoginToken removes the named token (and may clean up other expired tokens).
+	RemoveLoginToken(ctx context.Context, token string) error
+
+	// GetLoginTokenDataByToken returns the data associated with the given token.
+	// May return sql.ErrNoRows.
+	GetLoginTokenDataByToken(ctx context.Context, token string) (*api.LoginTokenData, error)
 }

userapi/storage/devices/postgres/logintoken_table.go

@@ -0,0 +1,93 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package postgres
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+)
+
+type loginTokenStatements struct {
+	insertStmt        *sql.Stmt
+	deleteStmt        *sql.Stmt
+	selectByTokenStmt *sql.Stmt
+}
+
+// execSchema ensures tables and indices exist.
+func (s *loginTokenStatements) execSchema(db *sql.DB) error {
+	_, err := db.Exec(`
+CREATE TABLE IF NOT EXISTS login_tokens (
+	-- The random value of the token issued to a user
+	token TEXT NOT NULL PRIMARY KEY,
+	-- When the token expires
+	token_expires_at TIMESTAMP NOT NULL,
+
+    -- The mxid for this account
+	user_id TEXT NOT NULL
+);
+
+-- This index allows efficient garbage collection of expired tokens.
+CREATE INDEX IF NOT EXISTS login_tokens_expiration_idx ON login_tokens(token_expires_at);
+`)
+	return err
+}
+
+// prepare runs statement preparation.
+func (s *loginTokenStatements) prepare(db *sql.DB) error {
+	return sqlutil.StatementList{
+		{&s.insertStmt, "INSERT INTO login_tokens(token, token_expires_at, user_id) VALUES ($1, $2, $3)"},
+		{&s.deleteStmt, "DELETE FROM login_tokens WHERE token = $1 OR token_expires_at <= $2"},
+		{&s.selectByTokenStmt, "SELECT user_id FROM login_tokens WHERE token = $1 AND token_expires_at > $2"},
+	}.Prepare(db)
+}
+
+// insert adds an already generated token to the database.
+func (s *loginTokenStatements) insert(ctx context.Context, txn *sql.Tx, metadata *api.LoginTokenMetadata, data *api.LoginTokenData) error {
+	stmt := sqlutil.TxStmt(txn, s.insertStmt)
+	_, err := stmt.ExecContext(ctx, metadata.Token, metadata.Expiration.UTC(), data.UserID)
+	return err
+}
+
+// deleteByToken removes the named token.
+//
+// As a simple way to garbage-collect stale tokens, we also remove all expired tokens.
+// The login_tokens_expiration_idx index should make that efficient.
+func (s *loginTokenStatements) deleteByToken(ctx context.Context, txn *sql.Tx, token string) error {
+	stmt := sqlutil.TxStmt(txn, s.deleteStmt)
+	res, err := stmt.ExecContext(ctx, token, time.Now().UTC())
+	if err != nil {
+		return err
+	}
+	if n, err := res.RowsAffected(); err == nil && n > 1 {
+		util.GetLogger(ctx).WithField("num_deleted", n).Infof("Deleted %d login tokens (%d likely additional expired token)", n, n-1)
+	}
+	return nil
+}
+
+// selectByToken returns the data associated with the given token. May return sql.ErrNoRows.
+func (s *loginTokenStatements) selectByToken(ctx context.Context, token string) (*api.LoginTokenData, error) {
+	var data api.LoginTokenData
+	err := s.selectByTokenStmt.QueryRowContext(ctx, token, time.Now().UTC()).Scan(&data.UserID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &data, nil
+}

userapi/storage/devices/postgres/storage.go

@@ -19,6 +19,7 @@ import (
 	"crypto/rand"
 	"database/sql"
 	"encoding/base64"
+	"time"
 
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/setup/config"
@@ -27,28 +28,38 @@ import (
 	"github.com/matrix-org/gomatrixserverlib"
 )
 
-// The length of generated device IDs
+const (
-var deviceIDByteLength = 6
+	// The length of generated device IDs
+	deviceIDByteLength   = 6
+	loginTokenByteLength = 32
+)
 
 // Database represents a device database.
 type Database struct {
-	db      *sql.DB
+	db                 *sql.DB
-	devices devicesStatements
+	devices            devicesStatements
+	loginTokens        loginTokenStatements
+	loginTokenLifetime time.Duration
 }
 
 // NewDatabase creates a new device database
-func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserverlib.ServerName) (*Database, error) {
+func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserverlib.ServerName, loginTokenLifetime time.Duration) (*Database, error) {
 	db, err := sqlutil.Open(dbProperties)
 	if err != nil {
 		return nil, err
 	}
-	d := devicesStatements{}
+	var d devicesStatements
+	var lt loginTokenStatements
 
 	// Create tables before executing migrations so we don't fail if the table is missing,
 	// and THEN prepare statements so we don't fail due to referencing new columns
 	if err = d.execSchema(db); err != nil {
 		return nil, err
 	}
+	if err = lt.execSchema(db); err != nil {
+		return nil, err
+	}
+
 	m := sqlutil.NewMigrations()
 	deltas.LoadLastSeenTSIP(m)
 	if err = m.RunDeltas(db, dbProperties); err != nil {
@@ -58,8 +69,11 @@ func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserver
 	if err = d.prepare(db, serverName); err != nil {
 		return nil, err
 	}
+	if err = lt.prepare(db); err != nil {
+		return nil, err
+	}
 
-	return &Database{db, d}, nil
+	return &Database{db, d, lt, loginTokenLifetime}, nil
 }
 
 // GetDeviceByAccessToken returns the device matching the given access token.
@@ -210,3 +224,47 @@ func (d *Database) UpdateDeviceLastSeen(ctx context.Context, localpart, deviceID
 		return d.devices.updateDeviceLastSeen(ctx, txn, localpart, deviceID, ipAddr)
 	})
 }
+
+// CreateLoginToken generates a token, stores and returns it. The lifetime is
+// determined by the loginTokenLifetime given to the Database constructor.
+func (d *Database) CreateLoginToken(ctx context.Context, data *api.LoginTokenData) (*api.LoginTokenMetadata, error) {
+	tok, err := generateLoginToken()
+	if err != nil {
+		return nil, err
+	}
+	meta := &api.LoginTokenMetadata{
+		Token:      tok,
+		Expiration: time.Now().Add(d.loginTokenLifetime),
+	}
+
+	err = sqlutil.WithTransaction(d.db, func(txn *sql.Tx) error {
+		return d.loginTokens.insert(ctx, txn, meta, data)
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return meta, nil
+}
+
+func generateLoginToken() (string, error) {
+	b := make([]byte, loginTokenByteLength)
+	_, err := rand.Read(b)
+	if err != nil {
+		return "", err
+	}
+	return base64.RawURLEncoding.EncodeToString(b), nil
+}
+
+// RemoveLoginToken removes the named token (and may clean up other expired tokens).
+func (d *Database) RemoveLoginToken(ctx context.Context, token string) error {
+	return sqlutil.WithTransaction(d.db, func(txn *sql.Tx) error {
+		return d.loginTokens.deleteByToken(ctx, txn, token)
+	})
+}
+
+// GetLoginTokenDataByToken returns the data associated with the given token.
+// May return sql.ErrNoRows.
+func (d *Database) GetLoginTokenDataByToken(ctx context.Context, token string) (*api.LoginTokenData, error) {
+	return d.loginTokens.selectByToken(ctx, token)
+}

userapi/storage/devices/sqlite3/logintoken_table.go

@@ -0,0 +1,93 @@
+// Copyright 2021 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package sqlite3
+
+import (
+	"context"
+	"database/sql"
+	"time"
+
+	"github.com/matrix-org/dendrite/internal/sqlutil"
+	"github.com/matrix-org/dendrite/userapi/api"
+	"github.com/matrix-org/util"
+)
+
+type loginTokenStatements struct {
+	insertStmt        *sql.Stmt
+	deleteStmt        *sql.Stmt
+	selectByTokenStmt *sql.Stmt
+}
+
+// execSchema ensures tables and indices exist.
+func (s *loginTokenStatements) execSchema(db *sql.DB) error {
+	_, err := db.Exec(`
+CREATE TABLE IF NOT EXISTS login_tokens (
+	-- The random value of the token issued to a user
+	token TEXT NOT NULL PRIMARY KEY,
+	-- When the token expires
+	token_expires_at TIMESTAMP NOT NULL,
+
+    -- The mxid for this account
+	user_id TEXT NOT NULL
+);
+
+-- This index allows efficient garbage collection of expired tokens.
+CREATE INDEX IF NOT EXISTS login_tokens_expiration_idx ON login_tokens(token_expires_at);
+`)
+	return err
+}
+
+// prepare runs statement preparation.
+func (s *loginTokenStatements) prepare(db *sql.DB) error {
+	return sqlutil.StatementList{
+		{&s.insertStmt, "INSERT INTO login_tokens(token, token_expires_at, user_id) VALUES ($1, $2, $3)"},
+		{&s.deleteStmt, "DELETE FROM login_tokens WHERE token = $1 OR token_expires_at <= $2"},
+		{&s.selectByTokenStmt, "SELECT user_id FROM login_tokens WHERE token = $1 AND token_expires_at > $2"},
+	}.Prepare(db)
+}
+
+// insert adds an already generated token to the database.
+func (s *loginTokenStatements) insert(ctx context.Context, txn *sql.Tx, metadata *api.LoginTokenMetadata, data *api.LoginTokenData) error {
+	stmt := sqlutil.TxStmt(txn, s.insertStmt)
+	_, err := stmt.ExecContext(ctx, metadata.Token, metadata.Expiration.UTC(), data.UserID)
+	return err
+}
+
+// deleteByToken removes the named token.
+//
+// As a simple way to garbage-collect stale tokens, we also remove all expired tokens.
+// The login_tokens_expiration_idx index should make that efficient.
+func (s *loginTokenStatements) deleteByToken(ctx context.Context, txn *sql.Tx, token string) error {
+	stmt := sqlutil.TxStmt(txn, s.deleteStmt)
+	res, err := stmt.ExecContext(ctx, token, time.Now().UTC())
+	if err != nil {
+		return err
+	}
+	if n, err := res.RowsAffected(); err == nil && n > 1 {
+		util.GetLogger(ctx).WithField("num_deleted", n).Infof("Deleted %d login tokens (%d likely additional expired token)", n, n-1)
+	}
+	return nil
+}
+
+// selectByToken returns the data associated with the given token. May return sql.ErrNoRows.
+func (s *loginTokenStatements) selectByToken(ctx context.Context, token string) (*api.LoginTokenData, error) {
+	var data api.LoginTokenData
+	err := s.selectByTokenStmt.QueryRowContext(ctx, token, time.Now().UTC()).Scan(&data.UserID)
+	if err != nil {
+		return nil, err
+	}
+
+	return &data, nil
+}

userapi/storage/devices/sqlite3/storage.go

@@ -19,6 +19,7 @@ import (
 	"crypto/rand"
 	"database/sql"
 	"encoding/base64"
+	"time"
 
 	"github.com/matrix-org/dendrite/internal/sqlutil"
 	"github.com/matrix-org/dendrite/setup/config"
@@ -27,30 +28,41 @@ import (
 	"github.com/matrix-org/gomatrixserverlib"
 )
 
-// The length of generated device IDs
+const (
-var deviceIDByteLength = 6
+	// The length of generated device IDs
+	deviceIDByteLength = 6
+
+	loginTokenByteLength = 32
+)
 
 // Database represents a device database.
 type Database struct {
-	db      *sql.DB
+	db                 *sql.DB
-	writer  sqlutil.Writer
+	writer             sqlutil.Writer
-	devices devicesStatements
+	devices            devicesStatements
+	loginTokens        loginTokenStatements
+	loginTokenLifetime time.Duration
 }
 
 // NewDatabase creates a new device database
-func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserverlib.ServerName) (*Database, error) {
+func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserverlib.ServerName, loginTokenLifetime time.Duration) (*Database, error) {
 	db, err := sqlutil.Open(dbProperties)
 	if err != nil {
 		return nil, err
 	}
 	writer := sqlutil.NewExclusiveWriter()
-	d := devicesStatements{}
+	var d devicesStatements
+	var lt loginTokenStatements
 
 	// Create tables before executing migrations so we don't fail if the table is missing,
 	// and THEN prepare statements so we don't fail due to referencing new columns
 	if err = d.execSchema(db); err != nil {
 		return nil, err
 	}
+	if err = lt.execSchema(db); err != nil {
+		return nil, err
+	}
+
 	m := sqlutil.NewMigrations()
 	deltas.LoadLastSeenTSIP(m)
 	if err = m.RunDeltas(db, dbProperties); err != nil {
@@ -59,7 +71,10 @@ func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserver
 	if err = d.prepare(db, writer, serverName); err != nil {
 		return nil, err
 	}
-	return &Database{db, writer, d}, nil
+	if err = lt.prepare(db); err != nil {
+		return nil, err
+	}
+	return &Database{db, writer, d, lt, loginTokenLifetime}, nil
 }
 
 // GetDeviceByAccessToken returns the device matching the given access token.
@@ -210,3 +225,47 @@ func (d *Database) UpdateDeviceLastSeen(ctx context.Context, localpart, deviceID
 		return d.devices.updateDeviceLastSeen(ctx, txn, localpart, deviceID, ipAddr)
 	})
 }
+
+// CreateLoginToken generates a token, stores and returns it. The lifetime is
+// determined by the loginTokenLifetime given to the Database constructor.
+func (d *Database) CreateLoginToken(ctx context.Context, data *api.LoginTokenData) (*api.LoginTokenMetadata, error) {
+	tok, err := generateLoginToken()
+	if err != nil {
+		return nil, err
+	}
+	meta := &api.LoginTokenMetadata{
+		Token:      tok,
+		Expiration: time.Now().Add(d.loginTokenLifetime),
+	}
+
+	err = d.writer.Do(d.db, nil, func(txn *sql.Tx) error {
+		return d.loginTokens.insert(ctx, txn, meta, data)
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	return meta, nil
+}
+
+func generateLoginToken() (string, error) {
+	b := make([]byte, loginTokenByteLength)
+	_, err := rand.Read(b)
+	if err != nil {
+		return "", err
+	}
+	return base64.RawURLEncoding.EncodeToString(b), nil
+}
+
+// RemoveLoginToken removes the named token (and may clean up other expired tokens).
+func (d *Database) RemoveLoginToken(ctx context.Context, token string) error {
+	return d.writer.Do(d.db, nil, func(txn *sql.Tx) error {
+		return d.loginTokens.deleteByToken(ctx, txn, token)
+	})
+}
+
+// GetLoginTokenDataByToken returns the data associated with the given token.
+// May return sql.ErrNoRows.
+func (d *Database) GetLoginTokenDataByToken(ctx context.Context, token string) (*api.LoginTokenData, error) {
+	return d.loginTokens.selectByToken(ctx, token)
+}

userapi/storage/devices/storage.go

@@ -19,6 +19,7 @@ package devices
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/userapi/storage/devices/postgres"
@@ -27,13 +28,14 @@ import (
 )
 
 // NewDatabase opens a new Postgres or Sqlite database (based on dataSourceName scheme)
-// and sets postgres connection parameters
+// and sets postgres connection parameters. loginTokenLifetime determines how long a
-func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserverlib.ServerName) (Database, error) {
+// login token from CreateLoginToken is valid.
+func NewDatabase(dbProperties *config.DatabaseOptions, serverName gomatrixserverlib.ServerName, loginTokenLifetime time.Duration) (Database, error) {
 	switch {
 	case dbProperties.ConnectionString.IsSQLite():
-		return sqlite3.NewDatabase(dbProperties, serverName)
+		return sqlite3.NewDatabase(dbProperties, serverName, loginTokenLifetime)
 	case dbProperties.ConnectionString.IsPostgres():
-		return postgres.NewDatabase(dbProperties, serverName)
+		return postgres.NewDatabase(dbProperties, serverName, loginTokenLifetime)
 	default:
 		return nil, fmt.Errorf("unexpected database type")
 	}

userapi/storage/devices/storage_wasm.go

@@ -16,6 +16,7 @@ package devices
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/matrix-org/dendrite/setup/config"
 	"github.com/matrix-org/dendrite/userapi/storage/devices/sqlite3"
@@ -25,10 +26,11 @@ import (
 func NewDatabase(
 	dbProperties *config.DatabaseOptions,
 	serverName gomatrixserverlib.ServerName,
+	loginTokenLifetime time.Duration,
 ) (Database, error) {
 	switch {
 	case dbProperties.ConnectionString.IsSQLite():
-		return sqlite3.NewDatabase(dbProperties, serverName)
+		return sqlite3.NewDatabase(dbProperties, serverName, loginTokenLifetime)
 	case dbProperties.ConnectionString.IsPostgres():
 		return nil, fmt.Errorf("can't use Postgres implementation")
 	default:

userapi/userapi.go

@@ -15,6 +15,8 @@
 package userapi
 
 import (
+	"time"
+
 	"github.com/gorilla/mux"
 	keyapi "github.com/matrix-org/dendrite/keyserver/api"
 	"github.com/matrix-org/dendrite/setup/config"
@@ -26,6 +28,13 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+// defaultLoginTokenLifetime determines how old a valid token may be.
+//
+// NOTSPEC: The current spec says "SHOULD be limited to around five
+// seconds". Since TCP retries are on the order of 3 s, 5 s sounds very low.
+// Synapse uses 2 min (https://github.com/matrix-org/synapse/blob/78d5f91de1a9baf4dbb0a794cb49a799f29f7a38/synapse/handlers/auth.py#L1323-L1325).
+const defaultLoginTokenLifetime = 2 * time.Minute
+
 // AddInternalRoutes registers HTTP handlers for the internal API. Invokes functions
 // on the given input API.
 func AddInternalRoutes(router *mux.Router, intAPI api.UserInternalAPI) {
@@ -37,11 +46,21 @@ func AddInternalRoutes(router *mux.Router, intAPI api.UserInternalAPI) {
 func NewInternalAPI(
 	accountDB accounts.Database, cfg *config.UserAPI, appServices []config.ApplicationService, keyAPI keyapi.KeyInternalAPI,
 ) api.UserInternalAPI {
-	deviceDB, err := devices.NewDatabase(&cfg.DeviceDatabase, cfg.Matrix.ServerName)
+	deviceDB, err := devices.NewDatabase(&cfg.DeviceDatabase, cfg.Matrix.ServerName, defaultLoginTokenLifetime)
 	if err != nil {
 		logrus.WithError(err).Panicf("failed to connect to device db")
 	}
 
+	return newInternalAPI(accountDB, deviceDB, cfg, appServices, keyAPI)
+}
+
+func newInternalAPI(
+	accountDB accounts.Database,
+	deviceDB devices.Database,
+	cfg *config.UserAPI,
+	appServices []config.ApplicationService,
+	keyAPI keyapi.KeyInternalAPI,
+) api.UserInternalAPI {
 	return &internal.UserInternalAPI{
 		AccountDB:   accountDB,
 		DeviceDB:    deviceDB,

userapi/userapi_test.go

@@ -1,4 +1,18 @@
-package userapi_test
+// Copyright 2020 The Matrix.org Foundation C.I.C.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package userapi
 
 import (
 	"context"
@@ -6,15 +20,16 @@ import (
 	"net/http"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/gorilla/mux"
 	"github.com/matrix-org/dendrite/internal/httputil"
 	"github.com/matrix-org/dendrite/internal/test"
 	"github.com/matrix-org/dendrite/setup/config"
-	"github.com/matrix-org/dendrite/userapi"
 	"github.com/matrix-org/dendrite/userapi/api"
 	"github.com/matrix-org/dendrite/userapi/inthttp"
 	"github.com/matrix-org/dendrite/userapi/storage/accounts"
+	"github.com/matrix-org/dendrite/userapi/storage/devices"
 	"github.com/matrix-org/gomatrixserverlib"
 	"golang.org/x/crypto/bcrypt"
 )
@@ -23,31 +38,41 @@ const (
 	serverName = gomatrixserverlib.ServerName("example.com")
 )
 
-func MustMakeInternalAPI(t *testing.T) (api.UserInternalAPI, accounts.Database) {
+type apiTestOpts struct {
-	accountDB, err := accounts.NewDatabase(&config.DatabaseOptions{
+	loginTokenLifetime time.Duration
-		ConnectionString: "file::memory:",
+}
-	}, serverName, bcrypt.MinCost, config.DefaultOpenIDTokenLifetimeMS)
+
+func MustMakeInternalAPI(t *testing.T, opts apiTestOpts) (api.UserInternalAPI, accounts.Database) {
+	if opts.loginTokenLifetime == 0 {
+		opts.loginTokenLifetime = defaultLoginTokenLifetime
+	}
+	dbopts := &config.DatabaseOptions{
+		ConnectionString:   "file::memory:",
+		MaxOpenConnections: 1,
+		MaxIdleConnections: 1,
+	}
+	accountDB, err := accounts.NewDatabase(dbopts, serverName, bcrypt.MinCost, config.DefaultOpenIDTokenLifetimeMS)
 	if err != nil {
 		t.Fatalf("failed to create account DB: %s", err)
 	}
+	deviceDB, err := devices.NewDatabase(dbopts, serverName, opts.loginTokenLifetime)
+	if err != nil {
+		t.Fatalf("failed to create device DB: %s", err)
+	}
+
 	cfg := &config.UserAPI{
-		DeviceDatabase: config.DatabaseOptions{
-			ConnectionString:   "file::memory:",
-			MaxOpenConnections: 1,
-			MaxIdleConnections: 1,
-		},
 		Matrix: &config.Global{
 			ServerName: serverName,
 		},
 	}
 
-	return userapi.NewInternalAPI(accountDB, cfg, nil, nil), accountDB
+	return newInternalAPI(accountDB, deviceDB, cfg, nil, nil), accountDB
 }
 
 func TestQueryProfile(t *testing.T) {
 	aliceAvatarURL := "mxc://example.com/alice"
 	aliceDisplayName := "Alice"
-	userAPI, accountDB := MustMakeInternalAPI(t)
+	userAPI, accountDB := MustMakeInternalAPI(t, apiTestOpts{})
 	_, err := accountDB.CreateAccount(context.TODO(), "alice", "foobar", "")
 	if err != nil {
 		t.Fatalf("failed to make account: %s", err)
@@ -106,7 +131,7 @@ func TestQueryProfile(t *testing.T) {
 
 	t.Run("HTTP API", func(t *testing.T) {
 		router := mux.NewRouter().PathPrefix(httputil.InternalPathPrefix).Subrouter()
-		userapi.AddInternalRoutes(router, userAPI)
+		AddInternalRoutes(router, userAPI)
 		apiURL, cancel := test.ListenAndServe(t, router, false)
 		defer cancel()
 		httpAPI, err := inthttp.NewUserAPIClient(apiURL, &http.Client{})
@@ -119,3 +144,115 @@ func TestQueryProfile(t *testing.T) {
 		runCases(userAPI)
 	})
 }
+
+func TestLoginToken(t *testing.T) {
+	ctx := context.Background()
+
+	t.Run("tokenLoginFlow", func(t *testing.T) {
+		userAPI, accountDB := MustMakeInternalAPI(t, apiTestOpts{})
+
+		_, err := accountDB.CreateAccount(ctx, "auser", "apassword", "")
+		if err != nil {
+			t.Fatalf("failed to make account: %s", err)
+		}
+
+		t.Log("Creating a login token like the SSO callback would...")
+
+		creq := api.PerformLoginTokenCreationRequest{
+			Data: api.LoginTokenData{UserID: "@auser:example.com"},
+		}
+		var cresp api.PerformLoginTokenCreationResponse
+		if err := userAPI.PerformLoginTokenCreation(ctx, &creq, &cresp); err != nil {
+			t.Fatalf("PerformLoginTokenCreation failed: %v", err)
+		}
+
+		if cresp.Metadata.Token == "" {
+			t.Errorf("PerformLoginTokenCreation Token: got %q, want non-empty", cresp.Metadata.Token)
+		}
+		if cresp.Metadata.Expiration.Before(time.Now()) {
+			t.Errorf("PerformLoginTokenCreation Expiration: got %v, want non-expired", cresp.Metadata.Expiration)
+		}
+
+		t.Log("Querying the login token like /login with m.login.token would...")
+
+		qreq := api.QueryLoginTokenRequest{Token: cresp.Metadata.Token}
+		var qresp api.QueryLoginTokenResponse
+		if err := userAPI.QueryLoginToken(ctx, &qreq, &qresp); err != nil {
+			t.Fatalf("QueryLoginToken failed: %v", err)
+		}
+
+		if qresp.Data == nil {
+			t.Errorf("QueryLoginToken Data: got %v, want non-nil", qresp.Data)
+		} else if want := "@auser:example.com"; qresp.Data.UserID != want {
+			t.Errorf("QueryLoginToken UserID: got %q, want %q", qresp.Data.UserID, want)
+		}
+
+		t.Log("Deleting the login token like /login with m.login.token would...")
+
+		dreq := api.PerformLoginTokenDeletionRequest{Token: cresp.Metadata.Token}
+		var dresp api.PerformLoginTokenDeletionResponse
+		if err := userAPI.PerformLoginTokenDeletion(ctx, &dreq, &dresp); err != nil {
+			t.Fatalf("PerformLoginTokenDeletion failed: %v", err)
+		}
+	})
+
+	t.Run("expiredTokenIsNotReturned", func(t *testing.T) {
+		userAPI, _ := MustMakeInternalAPI(t, apiTestOpts{loginTokenLifetime: -1 * time.Second})
+
+		creq := api.PerformLoginTokenCreationRequest{
+			Data: api.LoginTokenData{UserID: "@auser:example.com"},
+		}
+		var cresp api.PerformLoginTokenCreationResponse
+		if err := userAPI.PerformLoginTokenCreation(ctx, &creq, &cresp); err != nil {
+			t.Fatalf("PerformLoginTokenCreation failed: %v", err)
+		}
+
+		qreq := api.QueryLoginTokenRequest{Token: cresp.Metadata.Token}
+		var qresp api.QueryLoginTokenResponse
+		if err := userAPI.QueryLoginToken(ctx, &qreq, &qresp); err != nil {
+			t.Fatalf("QueryLoginToken failed: %v", err)
+		}
+
+		if qresp.Data != nil {
+			t.Errorf("QueryLoginToken Data: got %v, want nil", qresp.Data)
+		}
+	})
+
+	t.Run("deleteWorks", func(t *testing.T) {
+		userAPI, _ := MustMakeInternalAPI(t, apiTestOpts{})
+
+		creq := api.PerformLoginTokenCreationRequest{
+			Data: api.LoginTokenData{UserID: "@auser:example.com"},
+		}
+		var cresp api.PerformLoginTokenCreationResponse
+		if err := userAPI.PerformLoginTokenCreation(ctx, &creq, &cresp); err != nil {
+			t.Fatalf("PerformLoginTokenCreation failed: %v", err)
+		}
+
+		dreq := api.PerformLoginTokenDeletionRequest{Token: cresp.Metadata.Token}
+		var dresp api.PerformLoginTokenDeletionResponse
+		if err := userAPI.PerformLoginTokenDeletion(ctx, &dreq, &dresp); err != nil {
+			t.Fatalf("PerformLoginTokenDeletion failed: %v", err)
+		}
+
+		qreq := api.QueryLoginTokenRequest{Token: cresp.Metadata.Token}
+		var qresp api.QueryLoginTokenResponse
+		if err := userAPI.QueryLoginToken(ctx, &qreq, &qresp); err != nil {
+			t.Fatalf("QueryLoginToken failed: %v", err)
+		}
+
+		if qresp.Data != nil {
+			t.Errorf("QueryLoginToken Data: got %v, want nil", qresp.Data)
+		}
+	})
+
+	t.Run("deleteUnknownIsNoOp", func(t *testing.T) {
+		userAPI, _ := MustMakeInternalAPI(t, apiTestOpts{})
+
+		dreq := api.PerformLoginTokenDeletionRequest{Token: "non-existent token"}
+		var dresp api.PerformLoginTokenDeletionResponse
+		if err := userAPI.PerformLoginTokenDeletion(ctx, &dreq, &dresp); err != nil {
+			t.Fatalf("PerformLoginTokenDeletion failed: %v", err)
+		}
+	})
+}