Add single sign-on support via SSPI on Windows (#8463)

* Add single sign-on support via SSPI on Windows

* Ensure plugins implement interface

* Ensure plugins implement interface

* Move functions used only by the SSPI auth method to sspi_windows.go

* Field SSPISeparatorReplacement of AuthenticationForm should not be required via binding, as binding will insist the field is non-empty even if another login type is selected

* Fix breaking of oauth authentication on download links. Do not create new session with SSPI authentication on download links.

* Update documentation for the new 'SPNEGO with SSPI' login source

* Mention in documentation that ROOT_URL should contain the FQDN of the server

* Make sure that Contexter is not checking for active login sources when the ORM engine is not initialized (eg. when installing)

* Always initialize and free SSO methods, even if they are not enabled, as a method can be activated while the app is running (from Authentication sources)

* Add option in SSPIConfig for removing of domains from logon names

* Update helper text for StripDomainNames option

* Make sure handleSignIn() is called after a new user object is created by SSPI auth method

* Remove default value from text of form field helper

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Remove default value from text of form field helper

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Remove default value from text of form field helper

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Only make a query to the DB to check if SSPI is enabled on handlers that need that information for templates

* Remove code duplication

* Log errors in ActiveLoginSources

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Revert suffix of randomly generated E-mails for Reverse proxy authentication

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Revert unneeded white-space change in template

Co-Authored-By: Lauris BH <lauris@nix.lv>

* Add copyright comments at the top of new files

* Use loopback name for randomly generated emails

* Add locale tag for the SSPISeparatorReplacement field with proper casing

* Revert casing of SSPISeparatorReplacement field in locale file, moving it up, next to other form fields

* Update docs/content/doc/features/authentication.en-us.md

Co-Authored-By: guillep2k <18600385+guillep2k@users.noreply.github.com>

* Remove Priority() method and define the order in which SSO auth methods should be executed in one place

* Log authenticated username only if it's not empty

* Rephrase helper text for automatic creation of users

* Return error if more than one active SSPI auth source is found

* Change newUser() function to return error, letting caller log/handle the error

* Move isPublicResource, isPublicPage and handleSignIn functions outside SSPI auth method to allow other SSO methods to reuse them if needed

* Refactor initialization of the list containing SSO auth methods

* Validate SSPI settings on POST

* Change SSPI to only perform authentication on its own login page, API paths and download links. Leave Toggle middleware to redirect non authenticated users to login page

* Make 'Default language' in SSPI config empty, unless changed by admin

* Show error if admin tries to add a second authentication source of type SSPI

* Simplify declaration of global variable

* Rebuild gitgraph.js on Linux

* Make sure config values containing only whitespace are not accepted

docs/content/doc/features/authentication.en-us.md

@@ -216,3 +216,42 @@ configure this, set the fields below:
 
 - Log in to Gitea as an Administrator and click on "Authentication" under Admin Panel.
   Then click `Add New Source` and fill in the details, changing all where appropriate.
+
+## SPNEGO with SSPI (Kerberos/NTLM, for Windows only)
+
+Gitea supports SPNEGO single sign-on authentication (the scheme defined by RFC4559) for the web part of the server via the Security Support Provider Interface (SSPI) built in Windows. SSPI works only in Windows environments - when both the server and the clients are running Windows.
+
+Before activating SSPI single sign-on authentication (SSO) you have to prepare your environment:
+
+- Create a separate user account in active directory, under which the `gitea.exe` process will be running (eg. `user` under domain `domain.local`):
+
+- Create a service principal name for the host where `gitea.exe` is running with class `HTTP`:
+  - Start `Command Prompt` or `PowerShell` as a priviledged domain user (eg. Domain Administrator)
+  - Run the command below, replacing `host.domain.local` with the fully qualified domain name (FQDN) of the server where the web application will be running, and `domain\user` with the name of the account created in the previous step:
+  ```
+    setspn -A HTTP/host.domain.local domain\user
+  ```
+
+- Sign in (*sign out if you were already signed in*) with the user created
+
+- Make sure that `ROOT_URL` in the `[server]` section of `custom/conf/app.ini` is the fully qualified domain name of the server where the web application will be running - the same you used when creating the service principal name (eg. `host.domain.local`)
+
+- Start the web server (`gitea.exe web`)
+
+- Enable SSPI authentication by adding an `SPNEGO with SSPI` authentication source in `Site Administration -> Authentication Sources`
+
+- Sign in to a client computer in the same domain with any domain user (client computer, different from the server running `gitea.exe`)
+
+- If you are using Chrome, Edge or Internet Explorer, add the URL of the web app to the Local intranet sites (`Internet Options -> Security -> Local intranet -> Sites`)
+
+- Start Chrome, Edge or Internet Explorer and navigate to the FQDN URL of gitea (eg. `http://host.domain.local:3000`)
+
+- Click the `Sign In` button on the dashboard and choose SSPI to be automatically logged in with the same user that is currently logged on to the computer
+
+- If it does not work, make sure that:
+  - You are not running the web browser on the same server where gitea is running. You should be running the web browser on a domain joined computer (client) that is different from the server. If both the client and server are runnning on the same computer NTLM will be prefered over Kerberos.
+  - There is only one `HTTP/...` SPN for the host
+  - The SPN contains only the hostname, without the port
+  - You have added the URL of the web app to the `Local intranet zone`
+  - The clocks of the server and client should not differ with more than 5 minutes (depends on group policy)
+  - `Integrated Windows Authentication` should be enabled in Internet Explorer (under `Advanced settings`)

go.mod

@@ -78,6 +78,7 @@ require (
 	github.com/pquerna/otp v0.0.0-20160912161815-54653902c20e
 	github.com/prometheus/client_golang v1.1.0
 	github.com/prometheus/procfs v0.0.4 // indirect
+	github.com/quasoft/websspi v1.0.0
 	github.com/remyoudompheng/bigfft v0.0.0-20190321074620-2f0d2b0e0001 // indirect
 	github.com/russross/blackfriday/v2 v2.0.1
 	github.com/saintfish/chardet v0.0.0-20120816061221-3af4cd4741ca // indirect
@@ -101,7 +102,7 @@ require (
 	golang.org/x/crypto v0.0.0-20191117063200-497ca9f6d64f
 	golang.org/x/net v0.0.0-20191101175033-0deb6923b6d9
 	golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45
-	golang.org/x/sys v0.0.0-20190910064555-bbd175535a8b
+	golang.org/x/sys v0.0.0-20191010194322-b09406accb47
 	golang.org/x/text v0.3.2
 	golang.org/x/tools v0.0.0-20190910221609-7f5965fd7709 // indirect
 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect

go.sum

@@ -459,6 +459,8 @@ github.com/prometheus/procfs v0.0.4 h1:w8DjqFMJDjuVwdZBQoOozr4MVWOnwF7RcL/7uxBjY
 github.com/prometheus/procfs v0.0.4/go.mod h1:4A/X28fw3Fc593LaREMrKMqOKvUAntwMDaekg4FpcdQ=
 github.com/prometheus/tsdb v0.7.1/go.mod h1:qhTCs0VvXwvX/y3TZrWD7rabWM+ijKTux40TwIPHuXU=
 github.com/prometheus/tsdb v0.10.0/go.mod h1:oi49uRhEe9dPUTlS3JRZOwJuVi6tmh10QSgwXEyGCt4=
+github.com/quasoft/websspi v1.0.0 h1:5nDgdM5xSur9s+B5w2xQ5kxf5nUGqgFgU4W0aDLZ8Mw=
+github.com/quasoft/websspi v1.0.0/go.mod h1:HmVdl939dQ0WIXZhyik+ARdI03M6bQzaSEKcgpFmewk=
 github.com/rcrowley/go-metrics v0.0.0-20181016184325-3113b8401b8a/go.mod h1:bCqnVzQkZxMG4s8nGwiZ5l3QUCyqpo9Y+/ZMZ9VjZe4=
 github.com/remyoudompheng/bigfft v0.0.0-20190321074620-2f0d2b0e0001 h1:YDeskXpkNDhPdWN3REluVa46HQOVuVkjkd2sWnrABNQ=
 github.com/remyoudompheng/bigfft v0.0.0-20190321074620-2f0d2b0e0001/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
@@ -656,8 +658,8 @@ golang.org/x/sys v0.0.0-20190726091711-fc99dfbffb4e/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190730183949-1393eb018365/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190801041406-cbf593c0f2f3/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20190813064441-fde4db37ae7a/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190910064555-bbd175535a8b h1:3S2h5FadpNr0zUUCVZjlKIEYF+KaX/OBplTGo89CYHI=
-golang.org/x/sys v0.0.0-20190910064555-bbd175535a8b/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20191010194322-b09406accb47 h1:/XfQ9z7ib8eEJX2hdgFTZJ/ntt0swNk5oYBziWeTCvY=
+golang.org/x/sys v0.0.0-20191010194322-b09406accb47/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=

models/login_source.go

@@ -39,6 +39,7 @@ const (
 	LoginPAM              // 4
 	LoginDLDAP            // 5
 	LoginOAuth2           // 6
+	LoginSSPI             // 7
 )
 
 // LoginNames contains the name of LoginType values.
@@ -48,6 +49,7 @@ var LoginNames = map[LoginType]string{
 	LoginSMTP:   "SMTP",
 	LoginPAM:    "PAM",
 	LoginOAuth2: "OAuth2",
+	LoginSSPI:   "SPNEGO with SSPI",
 }
 
 // SecurityProtocolNames contains the name of SecurityProtocol values.
@@ -63,6 +65,7 @@ var (
 	_ core.Conversion = &SMTPConfig{}
 	_ core.Conversion = &PAMConfig{}
 	_ core.Conversion = &OAuth2Config{}
+	_ core.Conversion = &SSPIConfig{}
 )
 
 // LDAPConfig holds configuration for LDAP login source.
@@ -140,6 +143,25 @@ func (cfg *OAuth2Config) ToDB() ([]byte, error) {
 	return json.Marshal(cfg)
 }
 
+// SSPIConfig holds configuration for SSPI single sign-on.
+type SSPIConfig struct {
+	AutoCreateUsers      bool
+	AutoActivateUsers    bool
+	StripDomainNames     bool
+	SeparatorReplacement string
+	DefaultLanguage      string
+}
+
+// FromDB fills up an SSPIConfig from serialized format.
+func (cfg *SSPIConfig) FromDB(bs []byte) error {
+	return json.Unmarshal(bs, cfg)
+}
+
+// ToDB exports an SSPIConfig to a serialized format.
+func (cfg *SSPIConfig) ToDB() ([]byte, error) {
+	return json.Marshal(cfg)
+}
+
 // LoginSource represents an external way for authorizing users.
 type LoginSource struct {
 	ID            int64 `xorm:"pk autoincr"`
@@ -176,6 +198,8 @@ func (source *LoginSource) BeforeSet(colName string, val xorm.Cell) {
 			source.Cfg = new(PAMConfig)
 		case LoginOAuth2:
 			source.Cfg = new(OAuth2Config)
+		case LoginSSPI:
+			source.Cfg = new(SSPIConfig)
 		default:
 			panic("unrecognized login source type: " + com.ToStr(*val))
 		}
@@ -212,6 +236,11 @@ func (source *LoginSource) IsOAuth2() bool {
 	return source.Type == LoginOAuth2
 }
 
+// IsSSPI returns true of this source is of the SSPI type.
+func (source *LoginSource) IsSSPI() bool {
+	return source.Type == LoginSSPI
+}
+
 // HasTLS returns true of this source supports TLS.
 func (source *LoginSource) HasTLS() bool {
 	return ((source.IsLDAP() || source.IsDLDAP()) &&
@@ -264,6 +293,11 @@ func (source *LoginSource) OAuth2() *OAuth2Config {
 	return source.Cfg.(*OAuth2Config)
 }
 
+// SSPI returns SSPIConfig for this source, if of SSPI type.
+func (source *LoginSource) SSPI() *SSPIConfig {
+	return source.Cfg.(*SSPIConfig)
+}
+
 // CreateLoginSource inserts a LoginSource in the DB if not already
 // existing with the given name.
 func CreateLoginSource(source *LoginSource) error {
@@ -300,6 +334,38 @@ func LoginSources() ([]*LoginSource, error) {
 	return auths, x.Find(&auths)
 }
 
+// LoginSourcesByType returns all sources of the specified type
+func LoginSourcesByType(loginType LoginType) ([]*LoginSource, error) {
+	sources := make([]*LoginSource, 0, 1)
+	if err := x.Where("type = ?", loginType).Find(&sources); err != nil {
+		return nil, err
+	}
+	return sources, nil
+}
+
+// ActiveLoginSources returns all active sources of the specified type
+func ActiveLoginSources(loginType LoginType) ([]*LoginSource, error) {
+	sources := make([]*LoginSource, 0, 1)
+	if err := x.Where("is_actived = ? and type = ?", true, loginType).Find(&sources); err != nil {
+		return nil, err
+	}
+	return sources, nil
+}
+
+// IsSSPIEnabled returns true if there is at least one activated login
+// source of type LoginSSPI
+func IsSSPIEnabled() bool {
+	if !HasEngine {
+		return false
+	}
+	sources, err := ActiveLoginSources(LoginSSPI)
+	if err != nil {
+		log.Error("ActiveLoginSources: %v", err)
+		return false
+	}
+	return len(sources) > 0
+}
+
 // GetLoginSourceByID returns login source by given ID.
 func GetLoginSourceByID(id int64) (*LoginSource, error) {
 	source := new(LoginSource)
@@ -719,8 +785,8 @@ func UserSignIn(username, password string) (*User, error) {
 	}
 
 	for _, source := range sources {
-		if source.IsOAuth2() {
-			// don't try to authenticate against OAuth2 sources
+		if source.IsOAuth2() || source.IsSSPI() {
+			// don't try to authenticate against OAuth2 and SSPI sources here
 			continue
 		}
 		authUser, err := ExternalUserLogin(nil, username, password, source, true)