AuthN: Add auth proxy client (#61555)

* AuthN: set up boilerplate for proxy client

* AuthN: Implement Test for proxy client

* AuthN: parse accept list in constructor

* AuthN: add proxy client interface

* AuthN: handle error

* AuthN: Implement the proxy client interface for ldap

* AuthN: change reciever name

* AuthN: add grafana as a proxy client

* AuthN: for error returned

* AuthN: add tests for grafana proxy auth

* AuthN: swap order of grafan and ldap auth

* AuthN: Parse additional proxy headers in proxy client and pass down

pkg/services/authn/authn.go

@@ -25,6 +25,7 @@ const (
 	ClientRender    = "auth.client.render"
 	ClientSession   = "auth.client.session"
 	ClientForm      = "auth.client.form"
+	ClientProxy     = "auth.client.proxy"
 )
 
 const (
@@ -72,6 +73,10 @@ type PasswordClient interface {
 	AuthenticatePassword(ctx context.Context, r *Request, username, password string) (*Identity, error)
 }
 
+type ProxyClient interface {
+	AuthenticateProxy(ctx context.Context, r *Request, username string, additional map[string]string) (*Identity, error)
+}
+
 type Request struct {
 	// OrgID will be populated by authn.Service
 	OrgID int64

pkg/services/authn/authnimpl/service.go

@@ -64,12 +64,18 @@ func ProvideService(
 		s.clients[authn.ClientAnonymous] = clients.ProvideAnonymous(cfg, orgService)
 	}
 
+	var proxyClients []authn.ProxyClient
 	var passwordClients []authn.PasswordClient
-	if !s.cfg.DisableLogin {
-		passwordClients = append(passwordClients, clients.ProvideGrafana(userService))
-	}
 	if s.cfg.LDAPEnabled {
-		passwordClients = append(passwordClients, clients.ProvideLDAP(cfg))
+		ldap := clients.ProvideLDAP(cfg)
+		proxyClients = append(proxyClients, ldap)
+		passwordClients = append(passwordClients, ldap)
+	}
+
+	if !s.cfg.DisableLogin {
+		grafana := clients.ProvideGrafana(cfg, userService)
+		proxyClients = append(proxyClients, grafana)
+		passwordClients = append(passwordClients, grafana)
 	}
 
 	// if we have password clients configure check if basic auth or form auth is enabled
@@ -84,6 +90,15 @@ func ProvideService(
 		}
 	}
 
+	if s.cfg.AuthProxyEnabled && len(proxyClients) > 0 {
+		proxy, err := clients.ProvideProxy(cfg, proxyClients...)
+		if err != nil {
+			s.log.Error("failed to configure auth proxy", "err", err)
+		} else {
+			s.clients[authn.ClientProxy] = proxy
+		}
+	}
+
 	if s.cfg.JWTAuthEnabled {
 		s.clients[authn.ClientJWT] = clients.ProvideJWT(jwtService, cfg)
 	}

pkg/services/authn/authntest/mock.go

@@ -26,3 +26,16 @@ func (m MockClient) Test(ctx context.Context, r *authn.Request) bool {
 	}
 	return false
 }
+
+var _ authn.ProxyClient = new(MockProxyClient)
+
+type MockProxyClient struct {
+	AuthenticateProxyFunc func(ctx context.Context, r *authn.Request, username string, additional map[string]string) (*authn.Identity, error)
+}
+
+func (m MockProxyClient) AuthenticateProxy(ctx context.Context, r *authn.Request, username string, additional map[string]string) (*authn.Identity, error) {
+	if m.AuthenticateProxyFunc != nil {
+		return m.AuthenticateProxyFunc(ctx, r, username, additional)
+	}
+	return nil, nil
+}

pkg/services/authn/clients/grafana.go

@@ -4,23 +4,88 @@ import (
 	"context"
 	"crypto/subtle"
 	"errors"
+	"net/mail"
 
 	"github.com/grafana/grafana/pkg/services/authn"
+	"github.com/grafana/grafana/pkg/services/login"
+	"github.com/grafana/grafana/pkg/services/org"
 	"github.com/grafana/grafana/pkg/services/user"
+	"github.com/grafana/grafana/pkg/setting"
 	"github.com/grafana/grafana/pkg/util"
 )
 
+var _ authn.ProxyClient = new(Grafana)
 var _ authn.PasswordClient = new(Grafana)
 
-func ProvideGrafana(userService user.Service) *Grafana {
+func ProvideGrafana(cfg *setting.Cfg, userService user.Service) *Grafana {
-	return &Grafana{userService}
+	return &Grafana{cfg, userService}
 }
 
 type Grafana struct {
+	cfg         *setting.Cfg
 	userService user.Service
 }
 
-func (c Grafana) AuthenticatePassword(ctx context.Context, r *authn.Request, username, password string) (*authn.Identity, error) {
+func (c *Grafana) AuthenticateProxy(ctx context.Context, r *authn.Request, username string, additional map[string]string) (*authn.Identity, error) {
+	identity := &authn.Identity{
+		AuthModule: login.AuthProxyAuthModule,
+		AuthID:     username,
+		ClientParams: authn.ClientParams{
+			SyncUser:        true,
+			SyncTeamMembers: true,
+			AllowSignUp:     c.cfg.AuthProxyAutoSignUp,
+		},
+	}
+
+	switch c.cfg.AuthProxyHeaderProperty {
+	case "username":
+		identity.Login = username
+		addr, err := mail.ParseAddress(username)
+		if err == nil {
+			identity.Email = addr.Address
+		}
+	case "email":
+		identity.Login = username
+		identity.Email = username
+	default:
+		return nil, errInvalidProxyHeader.Errorf("invalid auth proxy header property, expected username or email but got: %s", c.cfg.AuthProxyHeaderProperty)
+	}
+
+	if v, ok := additional[proxyFieldName]; ok {
+		identity.Name = v
+	}
+
+	if v, ok := additional[proxyFieldEmail]; ok {
+		identity.Email = v
+	}
+
+	if v, ok := additional[proxyFieldLogin]; ok {
+		identity.Login = v
+	}
+
+	if v, ok := additional[proxyFieldRole]; ok {
+		role := org.RoleType(v)
+		if role.IsValid() {
+			orgID := int64(1)
+			if c.cfg.AutoAssignOrg && c.cfg.AutoAssignOrgId > 0 {
+				orgID = int64(c.cfg.AutoAssignOrgId)
+			}
+			identity.OrgID = orgID
+			identity.OrgRoles = map[int64]org.RoleType{orgID: role}
+		}
+	}
+
+	if v, ok := additional[proxyFieldGroups]; ok {
+		identity.Groups = util.SplitString(v)
+	}
+
+	identity.ClientParams.LookUpParams.Email = &identity.Email
+	identity.ClientParams.LookUpParams.Login = &identity.Login
+
+	return identity, nil
+}
+
+func (c *Grafana) AuthenticatePassword(ctx context.Context, r *authn.Request, username, password string) (*authn.Identity, error) {
 	usr, err := c.userService.GetByLogin(ctx, &user.GetUserByLoginQuery{LoginOrEmail: username})
 	if err != nil {
 		if errors.Is(err, user.ErrUserNotFound) {

pkg/services/authn/clients/grafana_test.go

@@ -2,16 +2,125 @@ package clients
 
 import (
 	"context"
+	"net/http"
 	"testing"
 
+	"github.com/grafana/grafana/pkg/models"
 	"github.com/grafana/grafana/pkg/services/authn"
 	"github.com/grafana/grafana/pkg/services/org"
 	"github.com/grafana/grafana/pkg/services/user"
 	"github.com/grafana/grafana/pkg/services/user/usertest"
+	"github.com/grafana/grafana/pkg/setting"
 	"github.com/grafana/grafana/pkg/util"
 	"github.com/stretchr/testify/assert"
 )
 
+func TestGrafana_AuthenticateProxy(t *testing.T) {
+	type testCase struct {
+		desc             string
+		req              *authn.Request
+		username         string
+		proxyProperty    string
+		additional       map[string]string
+		expectedErr      error
+		expectedIdentity *authn.Identity
+	}
+
+	tests := []testCase{
+		{
+			desc:          "expect valid identity",
+			username:      "test",
+			req:           &authn.Request{HTTPRequest: &http.Request{}},
+			proxyProperty: "username",
+			additional: map[string]string{
+				proxyFieldName:   "name",
+				proxyFieldRole:   "Viewer",
+				proxyFieldGroups: "grp1,grp2",
+				proxyFieldEmail:  "email@email.com",
+			},
+			expectedIdentity: &authn.Identity{
+				OrgID:      1,
+				OrgRoles:   map[int64]org.RoleType{1: org.RoleViewer},
+				Login:      "test",
+				Name:       "name",
+				Email:      "email@email.com",
+				AuthModule: "authproxy",
+				AuthID:     "test",
+				Groups:     []string{"grp1", "grp2"},
+				ClientParams: authn.ClientParams{
+					SyncUser:        true,
+					SyncTeamMembers: true,
+					AllowSignUp:     true,
+					LookUpParams: models.UserLookupParams{
+						Email: strPtr("email@email.com"),
+						Login: strPtr("test"),
+					},
+				},
+			},
+		},
+		{
+			desc:       "should set email as both email and login when configured proxy auth header property is email",
+			username:   "test@test.com",
+			req:        &authn.Request{HTTPRequest: &http.Request{Header: map[string][]string{}}},
+			additional: map[string]string{},
+			expectedIdentity: &authn.Identity{
+				Login:      "test@test.com",
+				Email:      "test@test.com",
+				AuthModule: "authproxy",
+				AuthID:     "test@test.com",
+				ClientParams: authn.ClientParams{
+					SyncUser:        true,
+					SyncTeamMembers: true,
+					AllowSignUp:     true,
+					LookUpParams: models.UserLookupParams{
+						Email: strPtr("test@test.com"),
+						Login: strPtr("test@test.com"),
+					},
+				},
+			},
+			proxyProperty: "email",
+		},
+		{
+			desc:          "should return error on invalid auth proxy header property",
+			req:           &authn.Request{HTTPRequest: &http.Request{Header: map[string][]string{}}},
+			proxyProperty: "other",
+			expectedErr:   errInvalidProxyHeader,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			cfg := setting.NewCfg()
+			cfg.AuthProxyAutoSignUp = true
+			cfg.AuthProxyHeaderProperty = tt.proxyProperty
+			c := ProvideGrafana(cfg, usertest.NewUserServiceFake())
+
+			identity, err := c.AuthenticateProxy(context.Background(), tt.req, tt.username, tt.additional)
+			assert.ErrorIs(t, err, tt.expectedErr)
+			if tt.expectedIdentity != nil {
+				assert.Equal(t, tt.expectedIdentity.OrgID, identity.OrgID)
+				assert.Equal(t, tt.expectedIdentity.Login, identity.Login)
+				assert.Equal(t, tt.expectedIdentity.Name, identity.Name)
+				assert.Equal(t, tt.expectedIdentity.Email, identity.Email)
+				assert.Equal(t, tt.expectedIdentity.AuthID, identity.AuthID)
+				assert.Equal(t, tt.expectedIdentity.AuthModule, identity.AuthModule)
+				assert.Equal(t, tt.expectedIdentity.Groups, identity.Groups)
+
+				assert.Equal(t, tt.expectedIdentity.ClientParams.SyncUser, identity.ClientParams.SyncUser)
+				assert.Equal(t, tt.expectedIdentity.ClientParams.AllowSignUp, identity.ClientParams.AllowSignUp)
+				assert.Equal(t, tt.expectedIdentity.ClientParams.SyncTeamMembers, identity.ClientParams.SyncTeamMembers)
+				assert.Equal(t, tt.expectedIdentity.ClientParams.EnableDisabledUsers, identity.ClientParams.EnableDisabledUsers)
+
+				assert.EqualValues(t, tt.expectedIdentity.ClientParams.LookUpParams.Email, identity.ClientParams.LookUpParams.Email)
+				assert.EqualValues(t, tt.expectedIdentity.ClientParams.LookUpParams.Login, identity.ClientParams.LookUpParams.Login)
+				assert.EqualValues(t, tt.expectedIdentity.ClientParams.LookUpParams.UserID, identity.ClientParams.LookUpParams.UserID)
+			} else {
+				assert.Nil(t, tt.expectedIdentity)
+			}
+		})
+	}
+}
+
 func TestGrafana_AuthenticatePassword(t *testing.T) {
 	type testCase struct {
 		desc                 string
@@ -60,7 +169,7 @@ func TestGrafana_AuthenticatePassword(t *testing.T) {
 				userService.ExpectedError = user.ErrUserNotFound
 			}
 
-			c := ProvideGrafana(userService)
+			c := ProvideGrafana(setting.NewCfg(), userService)
 			identity, err := c.AuthenticatePassword(context.Background(), &authn.Request{OrgID: 1}, tt.username, tt.password)
 			assert.ErrorIs(t, err, tt.expectedErr)
 			assert.EqualValues(t, tt.expectedIdentity, identity)

pkg/services/authn/clients/ldap.go

@@ -10,6 +10,7 @@ import (
 	"github.com/grafana/grafana/pkg/setting"
 )
 
+var _ authn.ProxyClient = new(LDAP)
 var _ authn.PasswordClient = new(LDAP)
 
 func ProvideLDAP(cfg *setting.Cfg) *LDAP {
@@ -21,6 +22,19 @@ type LDAP struct {
 	service ldapService
 }
 
+func (c *LDAP) AuthenticateProxy(ctx context.Context, r *authn.Request, username string, _ map[string]string) (*authn.Identity, error) {
+	info, err := c.service.User(username)
+	if errors.Is(err, multildap.ErrDidNotFindUser) {
+		return nil, errIdentityNotFound.Errorf("no user found: %w", err)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	return identityFromLDAPInfo(r.OrgID, info, c.cfg.LDAPAllowSignup), nil
+}
+
 func (c *LDAP) AuthenticatePassword(ctx context.Context, r *authn.Request, username, password string) (*authn.Identity, error) {
 	info, err := c.service.Login(&models.LoginUserQuery{
 		Username: username,
@@ -43,31 +57,12 @@ func (c *LDAP) AuthenticatePassword(ctx context.Context, r *authn.Request, usern
 		return nil, err
 	}
 
-	return &authn.Identity{
+	return identityFromLDAPInfo(r.OrgID, info, c.cfg.LDAPAllowSignup), nil
-		OrgID:          r.OrgID,
-		OrgRoles:       info.OrgRoles,
-		Login:          info.Login,
-		Name:           info.Name,
-		Email:          info.Email,
-		IsGrafanaAdmin: info.IsGrafanaAdmin,
-		AuthModule:     info.AuthModule,
-		AuthID:         info.AuthId,
-		Groups:         info.Groups,
-		ClientParams: authn.ClientParams{
-			SyncUser:            true,
-			SyncTeamMembers:     true,
-			AllowSignUp:         c.cfg.LDAPAllowSignup,
-			EnableDisabledUsers: true,
-			LookUpParams: models.UserLookupParams{
-				Login: &info.Login,
-				Email: &info.Email,
-			},
-		},
-	}, nil
 }
 
 type ldapService interface {
 	Login(query *models.LoginUserQuery) (*models.ExternalUserInfo, error)
+	User(username string) (*models.ExternalUserInfo, error)
 }
 
 // FIXME: remove the implementation if we convert ldap to an actual service
@@ -83,3 +78,37 @@ func (s *ldapServiceImpl) Login(query *models.LoginUserQuery) (*models.ExternalU
 
 	return multildap.New(cfg.Servers).Login(query)
 }
+
+func (s *ldapServiceImpl) User(username string) (*models.ExternalUserInfo, error) {
+	cfg, err := multildap.GetConfig(s.cfg)
+	if err != nil {
+		return nil, err
+	}
+
+	user, _, err := multildap.New(cfg.Servers).User(username)
+	return user, err
+}
+
+func identityFromLDAPInfo(orgID int64, info *models.ExternalUserInfo, allowSignup bool) *authn.Identity {
+	return &authn.Identity{
+		OrgID:          orgID,
+		OrgRoles:       info.OrgRoles,
+		Login:          info.Login,
+		Name:           info.Name,
+		Email:          info.Email,
+		IsGrafanaAdmin: info.IsGrafanaAdmin,
+		AuthModule:     info.AuthModule,
+		AuthID:         info.AuthId,
+		Groups:         info.Groups,
+		ClientParams: authn.ClientParams{
+			SyncUser:            true,
+			SyncTeamMembers:     true,
+			AllowSignUp:         allowSignup,
+			EnableDisabledUsers: true,
+			LookUpParams: models.UserLookupParams{
+				Login: &info.Login,
+				Email: &info.Email,
+			},
+		},
+	}
+}

pkg/services/authn/clients/ldap_test.go

@@ -8,11 +8,74 @@ import (
 	"github.com/grafana/grafana/pkg/services/authn"
 	"github.com/grafana/grafana/pkg/services/ldap"
 	"github.com/grafana/grafana/pkg/services/login"
+	"github.com/grafana/grafana/pkg/services/multildap"
 	"github.com/grafana/grafana/pkg/services/org"
 	"github.com/grafana/grafana/pkg/setting"
 	"github.com/stretchr/testify/assert"
 )
 
+func TestLDAP_AuthenticateProxy(t *testing.T) {
+	type testCase struct {
+		desc             string
+		username         string
+		expectedLDAPErr  error
+		expectedLDAPInfo *models.ExternalUserInfo
+		expectedErr      error
+		expectedIdentity *authn.Identity
+	}
+
+	tests := []testCase{
+		{
+			desc:     "should return valid identity when found by ldap service",
+			username: "test",
+			expectedLDAPInfo: &models.ExternalUserInfo{
+				AuthModule: login.LDAPAuthModule,
+				AuthId:     "123",
+				Email:      "test@test.com",
+				Login:      "test",
+				Name:       "test test",
+				Groups:     []string{"1", "2"},
+				OrgRoles:   map[int64]org.RoleType{1: org.RoleViewer},
+			},
+			expectedIdentity: &authn.Identity{
+				OrgID:      1,
+				OrgRoles:   map[int64]org.RoleType{1: org.RoleViewer},
+				Login:      "test",
+				Name:       "test test",
+				Email:      "test@test.com",
+				AuthModule: login.LDAPAuthModule,
+				AuthID:     "123",
+				Groups:     []string{"1", "2"},
+				ClientParams: authn.ClientParams{
+					SyncUser:            true,
+					SyncTeamMembers:     true,
+					AllowSignUp:         false,
+					EnableDisabledUsers: true,
+					LookUpParams: models.UserLookupParams{
+						Email: strPtr("test@test.com"),
+						Login: strPtr("test"),
+					},
+				},
+			},
+		},
+		{
+			desc:            "should return error when user is not found",
+			username:        "test",
+			expectedLDAPErr: multildap.ErrDidNotFindUser,
+			expectedErr:     errIdentityNotFound,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			c := &LDAP{cfg: setting.NewCfg(), service: fakeLDAPService{ExpectedInfo: tt.expectedLDAPInfo, ExpectedErr: tt.expectedLDAPErr}}
+			identity, err := c.AuthenticateProxy(context.Background(), &authn.Request{OrgID: 1}, tt.username, nil)
+			assert.ErrorIs(t, err, tt.expectedErr)
+			assert.EqualValues(t, tt.expectedIdentity, identity)
+		})
+	}
+}
+
 func TestLDAP_AuthenticatePassword(t *testing.T) {
 	type testCase struct {
 		desc             string
@@ -20,7 +83,7 @@ func TestLDAP_AuthenticatePassword(t *testing.T) {
 		password         string
 		expectedErr      error
 		expectedLDAPErr  error
-		expectedInfo     *models.ExternalUserInfo
+		expectedLDAPInfo *models.ExternalUserInfo
 		expectedIdentity *authn.Identity
 	}
 
@@ -29,7 +92,7 @@ func TestLDAP_AuthenticatePassword(t *testing.T) {
 			desc:     "should successfully authenticate with correct username and password",
 			username: "test",
 			password: "test123",
-			expectedInfo: &models.ExternalUserInfo{
+			expectedLDAPInfo: &models.ExternalUserInfo{
 				AuthModule: login.LDAPAuthModule,
 				AuthId:     "123",
 				Email:      "test@test.com",
@@ -77,7 +140,7 @@ func TestLDAP_AuthenticatePassword(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.desc, func(t *testing.T) {
-			c := &LDAP{cfg: setting.NewCfg(), service: fakeLDAPService{ExpectedInfo: tt.expectedInfo, ExpectedErr: tt.expectedLDAPErr}}
+			c := &LDAP{cfg: setting.NewCfg(), service: fakeLDAPService{ExpectedInfo: tt.expectedLDAPInfo, ExpectedErr: tt.expectedLDAPErr}}
 
 			identity, err := c.AuthenticatePassword(context.Background(), &authn.Request{OrgID: 1}, tt.username, tt.password)
 			assert.ErrorIs(t, err, tt.expectedErr)
@@ -100,3 +163,7 @@ type fakeLDAPService struct {
 func (f fakeLDAPService) Login(query *models.LoginUserQuery) (*models.ExternalUserInfo, error) {
 	return f.ExpectedInfo, f.ExpectedErr
 }
+
+func (f fakeLDAPService) User(username string) (*models.ExternalUserInfo, error) {
+	return f.ExpectedInfo, f.ExpectedErr
+}

pkg/services/authn/clients/proxy.go

@@ -0,0 +1,147 @@
+package clients
+
+import (
+	"context"
+	"fmt"
+	"net"
+	"path"
+	"strings"
+
+	"github.com/grafana/grafana/pkg/services/authn"
+	"github.com/grafana/grafana/pkg/setting"
+	"github.com/grafana/grafana/pkg/util"
+	"github.com/grafana/grafana/pkg/util/errutil"
+)
+
+const (
+	proxyFieldName   = "Name"
+	proxyFieldEmail  = "Email"
+	proxyFieldLogin  = "Login"
+	proxyFieldRole   = "Role"
+	proxyFieldGroups = "Groups"
+)
+
+var proxyFields = [...]string{proxyFieldName, proxyFieldEmail, proxyFieldLogin, proxyFieldRole, proxyFieldGroups}
+
+var (
+	errNotAcceptedIP      = errutil.NewBase(errutil.StatusUnauthorized, "auth-proxy.invalid-ip")
+	errEmptyProxyHeader   = errutil.NewBase(errutil.StatusUnauthorized, "auth-proxy.empty-header")
+	errInvalidProxyHeader = errutil.NewBase(errutil.StatusInternal, "auth-proxy.invalid-proxy-header")
+)
+
+var _ authn.Client = new(Proxy)
+
+func ProvideProxy(cfg *setting.Cfg, clients ...authn.ProxyClient) (*Proxy, error) {
+	list, err := parseAcceptList(cfg.AuthProxyWhitelist)
+	if err != nil {
+		return nil, err
+	}
+	return &Proxy{cfg, clients, list}, nil
+}
+
+type Proxy struct {
+	cfg         *setting.Cfg
+	clients     []authn.ProxyClient
+	acceptedIPs []*net.IPNet
+}
+
+func (c *Proxy) Authenticate(ctx context.Context, r *authn.Request) (*authn.Identity, error) {
+	if !c.isAllowedIP(r) {
+		return nil, errNotAcceptedIP.Errorf("request ip is not in the configured accept list")
+	}
+
+	username := getProxyHeader(r, c.cfg.AuthProxyHeaderName, c.cfg.AuthProxyHeadersEncoded)
+	if len(username) == 0 {
+		return nil, errEmptyProxyHeader.Errorf("no username provided in auth proxy header")
+	}
+
+	additional := getAdditionalProxyHeaders(r, c.cfg)
+
+	// FIXME: add cache to prevent sync on every request
+
+	var clientErr error
+	for _, proxyClient := range c.clients {
+		var identity *authn.Identity
+		identity, clientErr = proxyClient.AuthenticateProxy(ctx, r, username, additional)
+		if identity != nil {
+			return identity, nil
+		}
+	}
+
+	return nil, clientErr
+}
+
+func (c *Proxy) Test(ctx context.Context, r *authn.Request) bool {
+	return len(getProxyHeader(r, c.cfg.AuthProxyHeaderName, c.cfg.AuthProxyHeadersEncoded)) != 0
+}
+
+func (c *Proxy) isAllowedIP(r *authn.Request) bool {
+	if len(c.acceptedIPs) == 0 {
+		return true
+	}
+
+	host, _, err := net.SplitHostPort(r.HTTPRequest.RemoteAddr)
+	if err != nil {
+		return false
+	}
+
+	ip := net.ParseIP(host)
+	for _, v := range c.acceptedIPs {
+		if v.Contains(ip) {
+			return true
+		}
+	}
+
+	return false
+}
+
+func parseAcceptList(s string) ([]*net.IPNet, error) {
+	if len(strings.TrimSpace(s)) == 0 {
+		return nil, nil
+	}
+	addresses := strings.Split(s, ",")
+	list := make([]*net.IPNet, 0, len(addresses))
+	for _, addr := range addresses {
+		result, err := coerceProxyAddress(addr)
+		if err != nil {
+			return nil, err
+		}
+		list = append(list, result)
+	}
+	return list, nil
+}
+
+// coerceProxyAddress gets network of the presented CIDR notation
+func coerceProxyAddress(proxyAddr string) (*net.IPNet, error) {
+	proxyAddr = strings.TrimSpace(proxyAddr)
+	if !strings.Contains(proxyAddr, "/") {
+		proxyAddr = path.Join(proxyAddr, "32")
+	}
+
+	_, network, err := net.ParseCIDR(proxyAddr)
+	if err != nil {
+		return nil, fmt.Errorf("could not parse the network: %w", err)
+	}
+	return network, nil
+}
+
+func getProxyHeader(r *authn.Request, headerName string, encoded bool) string {
+	if r.HTTPRequest == nil {
+		return ""
+	}
+	v := r.HTTPRequest.Header.Get(headerName)
+	if encoded {
+		v = util.DecodeQuotedPrintable(v)
+	}
+	return v
+}
+
+func getAdditionalProxyHeaders(r *authn.Request, cfg *setting.Cfg) map[string]string {
+	additional := make(map[string]string, len(proxyFields))
+	for _, k := range proxyFields {
+		if v := getProxyHeader(r, cfg.AuthProxyHeaders[k], cfg.AuthProxyHeadersEncoded); v != "" {
+			additional[k] = v
+		}
+	}
+	return additional
+}

pkg/services/authn/clients/proxy_test.go

@@ -0,0 +1,172 @@
+package clients
+
+import (
+	"context"
+	"net/http"
+	"testing"
+
+	"github.com/grafana/grafana/pkg/services/authn/authntest"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/grafana/grafana/pkg/services/authn"
+	"github.com/grafana/grafana/pkg/setting"
+)
+
+func TestProxy_Authenticate(t *testing.T) {
+	type testCase struct {
+		desc               string
+		req                *authn.Request
+		ips                string
+		proxyHeader        string
+		proxyHeaders       map[string]string
+		expectedErr        error
+		expectedUsername   string
+		expectedAdditional map[string]string
+	}
+
+	tests := []testCase{
+		{
+			desc: "should authenticate using passed in proxy client",
+			ips:  "127.0.0.1",
+			req: &authn.Request{
+				HTTPRequest: &http.Request{
+					Header: map[string][]string{
+						"X-Username": {"username"},
+						"X-Name":     {"name"},
+						"X-Email":    {"email"},
+						"X-Login":    {"login"},
+						"X-Role":     {"Viewer"},
+						"X-Group":    {"grp1,grp2"},
+					},
+					RemoteAddr: "127.0.0.1:333",
+				},
+			},
+			proxyHeader: "X-Username",
+			proxyHeaders: map[string]string{
+				proxyFieldName:   "X-Name",
+				proxyFieldEmail:  "X-Email",
+				proxyFieldLogin:  "X-Login",
+				proxyFieldRole:   "X-Role",
+				proxyFieldGroups: "X-Group",
+			},
+			expectedUsername: "username",
+			expectedAdditional: map[string]string{
+				proxyFieldName:   "name",
+				proxyFieldEmail:  "email",
+				proxyFieldLogin:  "login",
+				proxyFieldRole:   "Viewer",
+				proxyFieldGroups: "grp1,grp2",
+			},
+		},
+		{
+			desc: "should fail when proxy header is empty",
+			req: &authn.Request{
+				HTTPRequest: &http.Request{Header: map[string][]string{
+					"X-Username": {""},
+					"X-Name":     {"name"},
+					"X-Email":    {"email"},
+					"X-Login":    {"login"},
+					"X-Role":     {"Viewer"},
+					"X-Group":    {"grp1,grp2"},
+				}},
+			},
+			proxyHeader: "X-Username",
+			proxyHeaders: map[string]string{
+				proxyFieldName:   "X-Name",
+				proxyFieldEmail:  "X-Email",
+				proxyFieldLogin:  "X-Login",
+				proxyFieldRole:   "X-Role",
+				proxyFieldGroups: "X-Group",
+			},
+			expectedErr: errEmptyProxyHeader,
+		},
+		{
+			desc: "should fail when caller ip is not in accept list",
+			req: &authn.Request{
+				HTTPRequest: &http.Request{
+					Header:     map[string][]string{},
+					RemoteAddr: "127.0.0.2:333",
+				},
+			},
+			ips:         "127.0.0.1",
+			expectedErr: errNotAcceptedIP,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			cfg := setting.NewCfg()
+			cfg.AuthProxyHeaderName = "X-Username"
+			cfg.AuthProxyHeaders = tt.proxyHeaders
+			cfg.AuthProxyWhitelist = tt.ips
+
+			calledUsername := ""
+			var calledAdditional map[string]string
+
+			proxyClient := authntest.MockProxyClient{AuthenticateProxyFunc: func(ctx context.Context, r *authn.Request, username string, additional map[string]string) (*authn.Identity, error) {
+				calledUsername = username
+				calledAdditional = additional
+				return nil, nil
+			}}
+			c, err := ProvideProxy(cfg, proxyClient)
+			require.NoError(t, err)
+
+			_, err = c.Authenticate(context.Background(), tt.req)
+			assert.ErrorIs(t, err, tt.expectedErr)
+			assert.Equal(t, tt.expectedUsername, calledUsername)
+			assert.EqualValues(t, tt.expectedAdditional, calledAdditional)
+		})
+	}
+}
+
+func TestProxy_Test(t *testing.T) {
+	type testCase struct {
+		desc       string
+		req        *authn.Request
+		expectedOK bool
+	}
+
+	tests := []testCase{
+		{
+			desc: "should return true when proxy header exists",
+			req: &authn.Request{
+				HTTPRequest: &http.Request{
+					Header: map[string][]string{"Proxy-Header": {"some value"}},
+				},
+			},
+			expectedOK: true,
+		},
+		{
+			desc: "should return false when proxy header exists but has no value",
+			req: &authn.Request{
+				HTTPRequest: &http.Request{
+					Header: map[string][]string{"Proxy-Header": {""}},
+				},
+			},
+			expectedOK: false,
+		},
+		{
+			desc: "should return false when no proxy header is set on request",
+			req: &authn.Request{
+				HTTPRequest: &http.Request{Header: map[string][]string{}},
+			},
+			expectedOK: false,
+		},
+		{
+			desc:       "should return false when no http request is present",
+			req:        &authn.Request{},
+			expectedOK: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.desc, func(t *testing.T) {
+			cfg := setting.NewCfg()
+			cfg.AuthProxyHeaderName = "Proxy-Header"
+
+			c, _ := ProvideProxy(cfg, nil)
+			assert.Equal(t, tt.expectedOK, c.Test(context.Background(), tt.req))
+		})
+	}
+}

pkg/services/contexthandler/auth_proxy_test.go

@@ -16,6 +16,7 @@ import (
 	"github.com/grafana/grafana/pkg/services/auth/authtest"
 	"github.com/grafana/grafana/pkg/services/authn/authntest"
 	"github.com/grafana/grafana/pkg/services/contexthandler/authproxy"
+	"github.com/grafana/grafana/pkg/services/featuremgmt"
 	"github.com/grafana/grafana/pkg/services/login/loginservice"
 	"github.com/grafana/grafana/pkg/services/org/orgtest"
 	"github.com/grafana/grafana/pkg/services/rendering"
@@ -106,7 +107,7 @@ func getContextHandler(t *testing.T) *ContextHandler {
 
 	return ProvideService(cfg, userAuthTokenSvc, authJWTSvc, remoteCacheSvc,
 		renderSvc, sqlStore, tracer, authProxy, loginService, nil, authenticator,
-		&userService, orgService, nil, nil, &authntest.FakeService{})
+		&userService, orgService, nil, featuremgmt.WithFeatures(), &authntest.FakeService{})
 }
 
 type fakeAuthenticator struct{}

pkg/services/contexthandler/contexthandler.go

@@ -714,6 +714,28 @@ func (h *ContextHandler) handleError(ctx *models.ReqContext, err error, statusCo
 }
 
 func (h *ContextHandler) initContextWithAuthProxy(reqContext *models.ReqContext, orgID int64) bool {
+	if h.features.IsEnabled(featuremgmt.FlagAuthnService) {
+		identity, ok, err := h.authnService.Authenticate(reqContext.Req.Context(), authn.ClientProxy, &authn.Request{HTTPRequest: reqContext.Req, Resp: reqContext.Resp})
+		if !ok {
+			return false
+		}
+
+		if err != nil {
+			writeErr(reqContext, err)
+		}
+
+		ctx := WithAuthHTTPHeader(reqContext.Req.Context(), h.Cfg.AuthProxyHeaderName)
+		for _, header := range h.Cfg.AuthProxyHeaders {
+			if header != "" {
+				ctx = WithAuthHTTPHeader(ctx, header)
+			}
+		}
+
+		*reqContext.Req = *reqContext.Req.WithContext(ctx)
+		reqContext.IsSignedIn = true
+		reqContext.SignedInUser = identity.SignedInUser()
+		return true
+	}
 	username := reqContext.Req.Header.Get(h.Cfg.AuthProxyHeaderName)
 
 	logger := log.New("auth.proxy")