3 files changed, 131 insertions, 0 deletions
diff --git a/services/auth/source/pam/assert_interface_test.go b/services/auth/source/pam/assert_interface_test.go
new file mode 100644
index 0000000000..a0bebdf9c6
--- /dev/null
+++ b/services/auth/source/pam/assert_interface_test.go
@@ -0,0 +1,22 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package pam_test
+
+import (
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/services/auth"
+	"code.gitea.io/gitea/services/auth/source/pam"
+)
+
+// This test file exists to assert that our Source exposes the interfaces that we expect
+// It tightly binds the interfaces and implementation without breaking go import cycles
+
+type sourceInterface interface {
+	auth.PasswordAuthenticator
+	models.LoginConfig
+	models.LoginSourceSettable
+}
+
+var _ (sourceInterface) = &pam.Source{}
diff --git a/services/auth/source/pam/source.go b/services/auth/source/pam/source.go
new file mode 100644
index 0000000000..b717ee6fe8
--- /dev/null
+++ b/services/auth/source/pam/source.go
@@ -0,0 +1,47 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package pam
+
+import (
+	"code.gitea.io/gitea/models"
+
+	jsoniter "github.com/json-iterator/go"
+)
+
+// __________  _____      _____
+// \______   \/  _  \    /     \
+//  |     ___/  /_\  \  /  \ /  \
+//  |    |  /    |    \/    Y    \
+//  |____|  \____|__  /\____|__  /
+//                  \/         \/
+
+// Source holds configuration for the PAM login source.
+type Source struct {
+	ServiceName string // pam service (e.g. system-auth)
+	EmailDomain string
+
+	// reference to the loginSource
+	loginSource *models.LoginSource
+}
+
+// FromDB fills up a PAMConfig from serialized format.
+func (source *Source) FromDB(bs []byte) error {
+	return models.JSONUnmarshalHandleDoubleEncode(bs, &source)
+}
+
+// ToDB exports a PAMConfig to a serialized format.
+func (source *Source) ToDB() ([]byte, error) {
+	json := jsoniter.ConfigCompatibleWithStandardLibrary
+	return json.Marshal(source)
+}
+
+// SetLoginSource sets the related LoginSource
+func (source *Source) SetLoginSource(loginSource *models.LoginSource) {
+	source.loginSource = loginSource
+}
+
+func init() {
+	models.RegisterLoginTypeConfig(models.LoginPAM, &Source{})
+}
diff --git a/services/auth/source/pam/source_authenticate.go b/services/auth/source/pam/source_authenticate.go
new file mode 100644
index 0000000000..6ca0642904
--- /dev/null
+++ b/services/auth/source/pam/source_authenticate.go
@@ -0,0 +1,62 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package pam
+
+import (
+	"fmt"
+	"strings"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/auth/pam"
+	"code.gitea.io/gitea/modules/setting"
+
+	"github.com/google/uuid"
+)
+
+// Authenticate queries if login/password is valid against the PAM,
+// and create a local user if success when enabled.
+func (source *Source) Authenticate(user *models.User, login, password string) (*models.User, error) {
+	pamLogin, err := pam.Auth(source.ServiceName, login, password)
+	if err != nil {
+		if strings.Contains(err.Error(), "Authentication failure") {
+			return nil, models.ErrUserNotExist{Name: login}
+		}
+		return nil, err
+	}
+
+	if user != nil {
+		return user, nil
+	}
+
+	// Allow PAM sources with `@` in their name, like from Active Directory
+	username := pamLogin
+	email := pamLogin
+	idx := strings.Index(pamLogin, "@")
+	if idx > -1 {
+		username = pamLogin[:idx]
+	}
+	if models.ValidateEmail(email) != nil {
+		if source.EmailDomain != "" {
+			email = fmt.Sprintf("%s@%s", username, source.EmailDomain)
+		} else {
+			email = fmt.Sprintf("%s@%s", username, setting.Service.NoReplyAddress)
+		}
+		if models.ValidateEmail(email) != nil {
+			email = uuid.New().String() + "@localhost"
+		}
+	}
+
+	user = &models.User{
+		LowerName:   strings.ToLower(username),
+		Name:        username,
+		Email:       email,
+		Passwd:      password,
+		LoginType:   models.LoginPAM,
+		LoginSource: source.loginSource.ID,
+		LoginName:   login, // This is what the user typed in
+		IsActive:    true,
+	}
+	return user, models.CreateUser(user)
+}