enterprise/stages: Add MTLS stage (#14296)

* prepare client auth with inbuilt server

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* introduce better IPC auth

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* init

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* start stage

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* only allow trusted proxies to set MTLS headers

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* more stage progress

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* dont fail if ipc_key doesn't exist

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* actually install app

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* add some tests

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* update API

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix unquote

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix int serial number not jsonable

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* init ui

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* add UI

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* unrelated: fix git pull in makefile

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix parse helper

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* add test for outpost

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* more tests and improvements

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* improve labels

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* add support for multiple CAs on brand

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* add support for multiple CAs to MTLS stage

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* dont log ipcuser secret views

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

* fix go mod

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

---------

Signed-off-by: Jens Langhammer <jens@goauthentik.io>

Makefile

@@ -169,8 +169,7 @@ gen-client-go: gen-clean-go  ## Build and install the authentik API for Golang
 ifeq ($(wildcard ${PWD}/${GEN_API_GO}/.*),)
 	git clone --depth 1 https://github.com/goauthentik/client-go.git ${PWD}/${GEN_API_GO}
 else
-	cd ${PWD}/${GEN_API_GO}
-	git pull
+	cd ${PWD}/${GEN_API_GO} && git pull
 endif
 	cp ${PWD}/schema.yml ${PWD}/${GEN_API_GO}
 	make -C ${PWD}/${GEN_API_GO} build

authentik/api/authentication.py

@@ -1,9 +1,12 @@
 """API Authentication"""
 
 from hmac import compare_digest
+from pathlib import Path
+from tempfile import gettempdir
 from typing import Any
 
 from django.conf import settings
+from django.contrib.auth.models import AnonymousUser
 from drf_spectacular.extensions import OpenApiAuthenticationExtension
 from rest_framework.authentication import BaseAuthentication, get_authorization_header
 from rest_framework.exceptions import AuthenticationFailed
@@ -11,11 +14,17 @@ from rest_framework.request import Request
 from structlog.stdlib import get_logger
 
 from authentik.core.middleware import CTX_AUTH_VIA
-from authentik.core.models import Token, TokenIntents, User
+from authentik.core.models import Token, TokenIntents, User, UserTypes
 from authentik.outposts.models import Outpost
 from authentik.providers.oauth2.constants import SCOPE_AUTHENTIK_API
 
 LOGGER = get_logger()
+_tmp = Path(gettempdir())
+try:
+    with open(_tmp / "authentik-core-ipc.key") as _f:
+        ipc_key = _f.read()
+except OSError:
+    ipc_key = None
 
 
 def validate_auth(header: bytes) -> str | None:
@@ -73,6 +82,11 @@ def auth_user_lookup(raw_header: bytes) -> User | None:
     if user:
         CTX_AUTH_VIA.set("secret_key")
         return user
+    # then try to auth via secret key (for embedded outpost/etc)
+    user = token_ipc(auth_credentials)
+    if user:
+        CTX_AUTH_VIA.set("ipc")
+        return user
     raise AuthenticationFailed("Token invalid/expired")
 
 
@@ -90,6 +104,43 @@ def token_secret_key(value: str) -> User | None:
     return outpost.user
 
 
+class IPCUser(AnonymousUser):
+    """'Virtual' user for IPC communication between authentik core and the authentik router"""
+
+    username = "authentik:system"
+    is_active = True
+    is_superuser = True
+
+    @property
+    def type(self):
+        return UserTypes.INTERNAL_SERVICE_ACCOUNT
+
+    def has_perm(self, perm, obj=None):
+        return True
+
+    def has_perms(self, perm_list, obj=None):
+        return True
+
+    def has_module_perms(self, module):
+        return True
+
+    @property
+    def is_anonymous(self):
+        return False
+
+    @property
+    def is_authenticated(self):
+        return True
+
+
+def token_ipc(value: str) -> User | None:
+    """Check if the token is the secret key
+    and return the service account for the managed outpost"""
+    if not ipc_key or not compare_digest(value, ipc_key):
+        return None
+    return IPCUser()
+
+
 class TokenAuthentication(BaseAuthentication):
     """Token-based authentication using HTTP Bearer authentication"""
 

authentik/brands/api.py

@@ -59,6 +59,7 @@ class BrandSerializer(ModelSerializer):
             "flow_device_code",
             "default_application",
             "web_certificate",
+            "client_certificates",
             "attributes",
         ]
         extra_kwargs = {
@@ -120,6 +121,7 @@ class BrandViewSet(UsedByMixin, ModelViewSet):
         "domain",
         "branding_title",
         "web_certificate__name",
+        "client_certificates__name",
     ]
     filterset_fields = [
         "brand_uuid",
@@ -136,6 +138,7 @@ class BrandViewSet(UsedByMixin, ModelViewSet):
         "flow_user_settings",
         "flow_device_code",
         "web_certificate",
+        "client_certificates",
     ]
     ordering = ["domain"]
 

authentik/brands/migrations/0010_brand_client_certificates_and_more.py

@@ -0,0 +1,37 @@
+# Generated by Django 5.1.9 on 2025-05-19 15:09
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("authentik_brands", "0009_brand_branding_default_flow_background"),
+        ("authentik_crypto", "0004_alter_certificatekeypair_name"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="brand",
+            name="client_certificates",
+            field=models.ManyToManyField(
+                blank=True,
+                default=None,
+                help_text="Certificates used for client authentication.",
+                to="authentik_crypto.certificatekeypair",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="brand",
+            name="web_certificate",
+            field=models.ForeignKey(
+                default=None,
+                help_text="Web Certificate used by the authentik Core webserver.",
+                null=True,
+                on_delete=django.db.models.deletion.SET_DEFAULT,
+                related_name="+",
+                to="authentik_crypto.certificatekeypair",
+            ),
+        ),
+    ]

authentik/brands/models.py

@@ -73,6 +73,13 @@ class Brand(SerializerModel):
         default=None,
         on_delete=models.SET_DEFAULT,
         help_text=_("Web Certificate used by the authentik Core webserver."),
+        related_name="+",
+    )
+    client_certificates = models.ManyToManyField(
+        CertificateKeyPair,
+        default=None,
+        blank=True,
+        help_text=_("Certificates used for client authentication."),
     )
     attributes = models.JSONField(default=dict, blank=True)
 

authentik/crypto/api.py

@@ -30,6 +30,7 @@ from structlog.stdlib import get_logger
 
 from authentik.core.api.used_by import UsedByMixin
 from authentik.core.api.utils import ModelSerializer, PassiveSerializer
+from authentik.core.models import UserTypes
 from authentik.crypto.apps import MANAGED_KEY
 from authentik.crypto.builder import CertificateBuilder, PrivateKeyAlg
 from authentik.crypto.models import CertificateKeyPair
@@ -272,11 +273,12 @@ class CertificateKeyPairViewSet(UsedByMixin, ModelViewSet):
     def view_certificate(self, request: Request, pk: str) -> Response:
         """Return certificate-key pairs certificate and log access"""
         certificate: CertificateKeyPair = self.get_object()
-        Event.new(  # noqa # nosec
-            EventAction.SECRET_VIEW,
-            secret=certificate,
-            type="certificate",
-        ).from_http(request)
+        if request.user.type != UserTypes.INTERNAL_SERVICE_ACCOUNT:
+            Event.new(  # noqa # nosec
+                EventAction.SECRET_VIEW,
+                secret=certificate,
+                type="certificate",
+            ).from_http(request)
         if "download" in request.query_params:
             # Mime type from https://pki-tutorial.readthedocs.io/en/latest/mime.html
             response = HttpResponse(
@@ -302,11 +304,12 @@ class CertificateKeyPairViewSet(UsedByMixin, ModelViewSet):
     def view_private_key(self, request: Request, pk: str) -> Response:
         """Return certificate-key pairs private key and log access"""
         certificate: CertificateKeyPair = self.get_object()
-        Event.new(  # noqa # nosec
-            EventAction.SECRET_VIEW,
-            secret=certificate,
-            type="private_key",
-        ).from_http(request)
+        if request.user.type != UserTypes.INTERNAL_SERVICE_ACCOUNT:
+            Event.new(  # noqa # nosec
+                EventAction.SECRET_VIEW,
+                secret=certificate,
+                type="private_key",
+            ).from_http(request)
         if "download" in request.query_params:
             # Mime type from https://pki-tutorial.readthedocs.io/en/latest/mime.html
             response = HttpResponse(certificate.key_data, content_type="application/x-pem-file")

authentik/enterprise/settings.py

@@ -19,6 +19,7 @@ TENANT_APPS = [
     "authentik.enterprise.providers.microsoft_entra",
     "authentik.enterprise.providers.ssf",
     "authentik.enterprise.stages.authenticator_endpoint_gdtc",
+    "authentik.enterprise.stages.mtls",
     "authentik.enterprise.stages.source",
 ]
 

authentik/enterprise/stages/mtls/api.py

@@ -0,0 +1,31 @@
+"""Mutual TLS Stage API Views"""
+
+from rest_framework.viewsets import ModelViewSet
+
+from authentik.core.api.used_by import UsedByMixin
+from authentik.enterprise.api import EnterpriseRequiredMixin
+from authentik.enterprise.stages.mtls.models import MutualTLSStage
+from authentik.flows.api.stages import StageSerializer
+
+
+class MutualTLSStageSerializer(EnterpriseRequiredMixin, StageSerializer):
+    """MutualTLSStage Serializer"""
+
+    class Meta:
+        model = MutualTLSStage
+        fields = StageSerializer.Meta.fields + [
+            "mode",
+            "certificate_authorities",
+            "cert_attribute",
+            "user_attribute",
+        ]
+
+
+class MutualTLSStageViewSet(UsedByMixin, ModelViewSet):
+    """MutualTLSStage Viewset"""
+
+    queryset = MutualTLSStage.objects.all()
+    serializer_class = MutualTLSStageSerializer
+    filterset_fields = "__all__"
+    ordering = ["name"]
+    search_fields = ["name"]

authentik/enterprise/stages/mtls/apps.py

@@ -0,0 +1,12 @@
+"""authentik stage app config"""
+
+from authentik.enterprise.apps import EnterpriseConfig
+
+
+class AuthentikEnterpriseStageMTLSConfig(EnterpriseConfig):
+    """authentik MTLS stage config"""
+
+    name = "authentik.enterprise.stages.mtls"
+    label = "authentik_stages_mtls"
+    verbose_name = "authentik Enterprise.Stages.MTLS"
+    default = True

authentik/enterprise/stages/mtls/migrations/0001_initial.py

@@ -0,0 +1,68 @@
+# Generated by Django 5.1.9 on 2025-05-19 18:29
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+        ("authentik_crypto", "0004_alter_certificatekeypair_name"),
+        ("authentik_flows", "0027_auto_20231028_1424"),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name="MutualTLSStage",
+            fields=[
+                (
+                    "stage_ptr",
+                    models.OneToOneField(
+                        auto_created=True,
+                        on_delete=django.db.models.deletion.CASCADE,
+                        parent_link=True,
+                        primary_key=True,
+                        serialize=False,
+                        to="authentik_flows.stage",
+                    ),
+                ),
+                (
+                    "mode",
+                    models.TextField(choices=[("optional", "Optional"), ("required", "Required")]),
+                ),
+                (
+                    "cert_attribute",
+                    models.TextField(
+                        choices=[
+                            ("subject", "Subject"),
+                            ("common_name", "Common Name"),
+                            ("email", "Email"),
+                        ]
+                    ),
+                ),
+                (
+                    "user_attribute",
+                    models.TextField(choices=[("username", "Username"), ("email", "Email")]),
+                ),
+                (
+                    "certificate_authorities",
+                    models.ManyToManyField(
+                        blank=True,
+                        default=None,
+                        help_text="Configure certificate authorities to validate the certificate against. This option has a higher priority than the `client_certificate` option on `Brand`.",
+                        to="authentik_crypto.certificatekeypair",
+                    ),
+                ),
+            ],
+            options={
+                "verbose_name": "Mutual TLS Stage",
+                "verbose_name_plural": "Mutual TLS Stages",
+                "permissions": [
+                    ("pass_outpost_certificate", "Permissions to pass Certificates for outposts.")
+                ],
+            },
+            bases=("authentik_flows.stage",),
+        ),
+    ]

authentik/enterprise/stages/mtls/models.py

@@ -0,0 +1,71 @@
+from django.db import models
+from django.utils.translation import gettext_lazy as _
+from rest_framework.serializers import Serializer
+
+from authentik.crypto.models import CertificateKeyPair
+from authentik.flows.models import Stage
+from authentik.flows.stage import StageView
+
+
+class TLSMode(models.TextChoices):
+    """Modes the TLS Stage can operate in"""
+
+    OPTIONAL = "optional"
+    REQUIRED = "required"
+
+
+class CertAttributes(models.TextChoices):
+    """Certificate attribute used for user matching"""
+
+    SUBJECT = "subject"
+    COMMON_NAME = "common_name"
+    EMAIL = "email"
+
+
+class UserAttributes(models.TextChoices):
+    """User attribute for user matching"""
+
+    USERNAME = "username"
+    EMAIL = "email"
+
+
+class MutualTLSStage(Stage):
+    """Authenticate/enroll users using a client-certificate."""
+
+    mode = models.TextField(choices=TLSMode.choices)
+
+    certificate_authorities = models.ManyToManyField(
+        CertificateKeyPair,
+        default=None,
+        blank=True,
+        help_text=_(
+            "Configure certificate authorities to validate the certificate against. "
+            "This option has a higher priority than the `client_certificate` option on `Brand`."
+        ),
+    )
+
+    cert_attribute = models.TextField(choices=CertAttributes.choices)
+    user_attribute = models.TextField(choices=UserAttributes.choices)
+
+    @property
+    def view(self) -> type[StageView]:
+        from authentik.enterprise.stages.mtls.stage import MTLSStageView
+
+        return MTLSStageView
+
+    @property
+    def serializer(self) -> type[Serializer]:
+        from authentik.enterprise.stages.mtls.api import MutualTLSStageSerializer
+
+        return MutualTLSStageSerializer
+
+    @property
+    def component(self) -> str:
+        return "ak-stage-mtls-form"
+
+    class Meta:
+        verbose_name = _("Mutual TLS Stage")
+        verbose_name_plural = _("Mutual TLS Stages")
+        permissions = [
+            ("pass_outpost_certificate", _("Permissions to pass Certificates for outposts.")),
+        ]

authentik/enterprise/stages/mtls/stage.py

@@ -0,0 +1,215 @@
+from binascii import hexlify
+from urllib.parse import unquote_plus
+
+from cryptography.exceptions import InvalidSignature
+from cryptography.hazmat.primitives import hashes
+from cryptography.x509 import Certificate, NameOID, ObjectIdentifier, load_pem_x509_certificate
+from django.utils.translation import gettext_lazy as _
+
+from authentik.brands.models import Brand
+from authentik.core.models import User
+from authentik.crypto.models import CertificateKeyPair
+from authentik.enterprise.stages.mtls.models import (
+    CertAttributes,
+    MutualTLSStage,
+    TLSMode,
+    UserAttributes,
+)
+from authentik.flows.challenge import AccessDeniedChallenge
+from authentik.flows.models import FlowDesignation
+from authentik.flows.planner import PLAN_CONTEXT_PENDING_USER
+from authentik.flows.stage import ChallengeStageView
+from authentik.root.middleware import ClientIPMiddleware
+from authentik.stages.password.stage import PLAN_CONTEXT_METHOD, PLAN_CONTEXT_METHOD_ARGS
+from authentik.stages.prompt.stage import PLAN_CONTEXT_PROMPT
+
+# All of these headers must only be accepted from "trusted" reverse proxies
+# See internal/web/proxy.go:39
+HEADER_PROXY_FORWARDED = "X-Forwarded-Client-Cert"
+HEADER_NGINX_FORWARDED = "SSL-Client-Cert"
+HEADER_TRAEFIK_FORWARDED = "X-Forwarded-TLS-Client-Cert"
+HEADER_OUTPOST_FORWARDED = "X-Authentik-Outpost-Certificate"
+
+
+PLAN_CONTEXT_CERTIFICATE = "certificate"
+
+
+class MTLSStageView(ChallengeStageView):
+
+    def __parse_single_cert(self, raw: str | None) -> list[Certificate]:
+        """Helper to parse a single certificate"""
+        if not raw:
+            return []
+        try:
+            cert = load_pem_x509_certificate(unquote_plus(raw).encode())
+            return [cert]
+        except ValueError as exc:
+            self.logger.info("Failed to parse certificate", exc=exc)
+            return []
+
+    def _parse_cert_xfcc(self) -> list[Certificate]:
+        """Parse certificates in the format given to us in
+        the format of the authentik router/envoy"""
+        xfcc_raw = self.request.headers.get(HEADER_PROXY_FORWARDED)
+        if not xfcc_raw:
+            return []
+        certs = []
+        for r_cert in xfcc_raw.split(","):
+            el = r_cert.split(";")
+            raw_cert = {k.split("=")[0]: k.split("=")[1] for k in el}
+            if "Cert" not in raw_cert:
+                continue
+            certs.extend(self.__parse_single_cert(raw_cert["Cert"]))
+        return certs
+
+    def _parse_cert_nginx(self) -> list[Certificate]:
+        """Parse certificates in the format nginx-ingress gives to us"""
+        sslcc_raw = self.request.headers.get(HEADER_NGINX_FORWARDED)
+        return self.__parse_single_cert(sslcc_raw)
+
+    def _parse_cert_traefik(self) -> list[Certificate]:
+        """Parse certificates in the format traefik gives to us"""
+        ftcc_raw = self.request.headers.get(HEADER_TRAEFIK_FORWARDED)
+        return self.__parse_single_cert(ftcc_raw)
+
+    def _parse_cert_outpost(self) -> list[Certificate]:
+        """Parse certificates in the format outposts give to us. Also authenticates
+        the outpost to ensure it has the permission to do so"""
+        user = ClientIPMiddleware.get_outpost_user(self.request)
+        if not user:
+            return []
+        if not user.has_perm(
+            "pass_outpost_certificate", self.executor.current_stage
+        ) and not user.has_perm("authentik_stages_mtls.pass_outpost_certificate"):
+            return []
+        outpost_raw = self.request.headers.get(HEADER_OUTPOST_FORWARDED)
+        return self.__parse_single_cert(outpost_raw)
+
+    def get_authorities(self) -> list[CertificateKeyPair] | None:
+        # We can't access `certificate_authorities` on `self.executor.current_stage`, as that would
+        # load the certificate into the directly referenced foreign key, which we have to pickle
+        # as part of the flow plan, and cryptography certs can't be pickled
+        stage: MutualTLSStage = (
+            MutualTLSStage.objects.filter(pk=self.executor.current_stage.pk)
+            .prefetch_related("certificate_authorities")
+            .first()
+        )
+        if stage.certificate_authorities.exists():
+            return stage.certificate_authorities.order_by("name")
+        brand: Brand = self.request.brand
+        if brand.client_certificates.exists():
+            return brand.client_certificates.order_by("name")
+        return None
+
+    def validate_cert(self, authorities: list[CertificateKeyPair], certs: list[Certificate]):
+        for _cert in certs:
+            for ca in authorities:
+                try:
+                    _cert.verify_directly_issued_by(ca.certificate)
+                    return _cert
+                except (InvalidSignature, TypeError, ValueError) as exc:
+                    self.logger.warning(
+                        "Discarding cert not issued by authority", cert=_cert, authority=ca, exc=exc
+                    )
+                    continue
+        return None
+
+    def check_if_user(self, cert: Certificate):
+        stage: MutualTLSStage = self.executor.current_stage
+        cert_attr = None
+        user_attr = None
+        match stage.cert_attribute:
+            case CertAttributes.SUBJECT:
+                cert_attr = cert.subject.rfc4514_string()
+            case CertAttributes.COMMON_NAME:
+                cert_attr = self.get_cert_attribute(cert, NameOID.COMMON_NAME)
+            case CertAttributes.EMAIL:
+                cert_attr = self.get_cert_attribute(cert, NameOID.EMAIL_ADDRESS)
+        match stage.user_attribute:
+            case UserAttributes.USERNAME:
+                user_attr = "username"
+            case UserAttributes.EMAIL:
+                user_attr = "email"
+        if not user_attr or not cert_attr:
+            return None
+        return User.objects.filter(**{user_attr: cert_attr}).first()
+
+    def _cert_to_dict(self, cert: Certificate) -> dict:
+        """Represent a certificate in a dictionary, as certificate objects cannot be pickled"""
+        return {
+            "serial_number": str(cert.serial_number),
+            "subject": cert.subject.rfc4514_string(),
+            "issuer": cert.issuer.rfc4514_string(),
+            "fingerprint_sha256": hexlify(cert.fingerprint(hashes.SHA256()), ":").decode("utf-8"),
+            "fingerprint_sha1": hexlify(cert.fingerprint(hashes.SHA256()), ":").decode("utf-8"),
+        }
+
+    def auth_user(self, user: User, cert: Certificate):
+        self.executor.plan.context[PLAN_CONTEXT_PENDING_USER] = user
+        self.executor.plan.context.setdefault(PLAN_CONTEXT_METHOD, "mtls")
+        self.executor.plan.context.setdefault(PLAN_CONTEXT_METHOD_ARGS, {})
+        self.executor.plan.context[PLAN_CONTEXT_METHOD_ARGS].update(
+            {"certificate": self._cert_to_dict(cert)}
+        )
+
+    def enroll_prepare_user(self, cert: Certificate):
+        self.executor.plan.context.setdefault(PLAN_CONTEXT_PROMPT, {})
+        self.executor.plan.context[PLAN_CONTEXT_PROMPT].update(
+            {
+                "email": self.get_cert_attribute(cert, NameOID.EMAIL_ADDRESS),
+                "name": self.get_cert_attribute(cert, NameOID.COMMON_NAME),
+            }
+        )
+        self.executor.plan.context[PLAN_CONTEXT_CERTIFICATE] = self._cert_to_dict(cert)
+
+    def get_cert_attribute(self, cert: Certificate, oid: ObjectIdentifier) -> str | None:
+        attr = cert.subject.get_attributes_for_oid(oid)
+        if len(attr) < 1:
+            return None
+        return str(attr[0].value)
+
+    def dispatch(self, request, *args, **kwargs):
+        stage: MutualTLSStage = self.executor.current_stage
+        certs = [
+            *self._parse_cert_xfcc(),
+            *self._parse_cert_nginx(),
+            *self._parse_cert_traefik(),
+            *self._parse_cert_outpost(),
+        ]
+        authorities = self.get_authorities()
+        if not authorities:
+            self.logger.warning("No Certificate authority found")
+            if stage.mode == TLSMode.OPTIONAL:
+                return self.executor.stage_ok()
+            if stage.mode == TLSMode.REQUIRED:
+                return super().dispatch(request, *args, **kwargs)
+        cert = self.validate_cert(authorities, certs)
+        if not cert and stage.mode == TLSMode.REQUIRED:
+            self.logger.warning("Client certificate required but no certificates given")
+            return super().dispatch(
+                request,
+                *args,
+                error_message=_("Certificate required but no certificate was given."),
+                **kwargs,
+            )
+        if not cert and stage.mode == TLSMode.OPTIONAL:
+            self.logger.info("No certificate given, continuing")
+            return self.executor.stage_ok()
+        existing_user = self.check_if_user(cert)
+        if self.executor.flow.designation == FlowDesignation.ENROLLMENT:
+            self.enroll_prepare_user(cert)
+        elif existing_user:
+            self.auth_user(existing_user, cert)
+        else:
+            return super().dispatch(
+                request, *args, error_message=_("No user found for certificate."), **kwargs
+            )
+        return self.executor.stage_ok()
+
+    def get_challenge(self, *args, error_message: str | None = None, **kwargs):
+        return AccessDeniedChallenge(
+            data={
+                "component": "ak-stage-access-denied",
+                "error_message": str(error_message or "Unknown error"),
+            }
+        )

authentik/enterprise/stages/mtls/tests/fixtures/ca.pem

@@ -0,0 +1,31 @@
+-----BEGIN CERTIFICATE-----
+MIIFXDCCA0SgAwIBAgIUBmV7zREyC1SPr72/75/L9zpwV18wDQYJKoZIhvcNAQEL
+BQAwRjEaMBgGA1UEAwwRYXV0aGVudGlrIFRlc3QgQ0ExEjAQBgNVBAoMCWF1dGhl
+bnRpazEUMBIGA1UECwwLU2VsZi1zaWduZWQwHhcNMjUwNDI3MTgzMDUwWhcNMzUw
+MzA3MTgzMDUwWjBGMRowGAYDVQQDDBFhdXRoZW50aWsgVGVzdCBDQTESMBAGA1UE
+CgwJYXV0aGVudGlrMRQwEgYDVQQLDAtTZWxmLXNpZ25lZDCCAiIwDQYJKoZIhvcN
+AQEBBQADggIPADCCAgoCggIBAMc0NxZj7j1mPu0aRToo8oMPdC3T99xgxnqdr18x
+LV4pWyi/YLghgZHqNQY2xNP6JIlSeUZD6KFUYT2sPL4Av/zSg5zO8bl+/lf7ckje
+O1/Bt5A8xtL0CpmpMDGiI6ibdDElaywM6AohisbxrV29pygSKGq2wugF/urqGtE+
+5z4y5Kt6qMdKkd0iXT+WagbQTIUlykFKgB0+qqTLzDl01lVDa/DoLl8Hqp45mVx2
+pqrGsSa3TCErLIv9hUlZklF7A8UV4ZB4JL20UKcP8dKzQClviNie17tpsUpOuy3A
+SQ6+guWTHTLJNCSdLn1xIqc5q+f5wd2dIDf8zXCTHj+Xp0bJE3Vgaq5R31K9+b+1
+2dDWz1KcNJaLEnw2+b0O8M64wTMLxhqOv7QfLUr6Pmg1ZymghjLcZ6bnU9e31Vza
+hlPKhxjqYQUC4Kq+oaYF6qdUeJy+dsYf0iDv5tTC+eReZDWIjxTPrNpwA773ZwT7
+WVmL7ULGpuP2g9rNvFBcZiN+i6d7CUoN+jd/iRdo79lrI0dfXiyy4bYgW/2HeZfF
+HaOsc1xsoqnJdWbWkX/ooyaCjAfm07kS3HiOzz4q3QW4wgGrwV8lEraLPxYYeOQu
+YcGMOM8NfnVkjc8gmyXUxedCje5Vz/Tu5fKrQEInnCmXxVsWbwr/LzEjMKAM/ivY
+0TXxAgMBAAGjQjBAMA8GA1UdEwEB/wQFMAMBAf8wDgYDVR0PAQH/BAQDAgGGMB0G
+A1UdDgQWBBTa+Ns6QzqlNvnTGszkouQQtZnVJDANBgkqhkiG9w0BAQsFAAOCAgEA
+NpJEDMXjuEIzSzafkxSshvjnt5sMYmzmvjNoRlkxgN2YcWvPoxbalGAYzcpyggT2
+6xZY8R4tvB1oNTCArqwf860kkofUoJCr88D/pU3Cv4JhjCWs4pmXTsvSqlBSlJbo
++jPBZwbn6it/6jcit6Be3rW2PtHe8tASd9Lf8/2r1ZvupXwPzcR84R4Z10ve2lqV
+xxcWlMmBh51CaYI0b1/WTe9Ua+wgkCVkxbf9zNcDQXjxw2ICWK+nR/4ld4nmqVm2
+C7nhvXwU8FAHl7ZgR2Z3PLrwPuhd+kd6NXQqNkS9A+n+1vSRLbRjmV8pwIPpdPEq
+nslUAGJJBHDUBArxC3gOJSB+WtmaCfzDu2gepMf9Ng1H2ZhwSF/FH3v3fsJqZkzz
+NBstT9KuNGQRYiCmAPJaoVAc9BoLa+BFML1govtWtpdmbFk8PZEcuUsP7iAZqFF1
+uuldPyZ8huGpQSR6Oq2bILRHowfGY0npTZAyxg0Vs8UMy1HTwNOp9OuRtArMZmsJ
+jFIx1QzRf9S1i6bYpOzOudoXj4ARkS1KmVExGjJFcIT0xlFSSERie2fEKSeEYOyG
+G+PA2qRt/F51FGOMm1ZscjPXqk2kt3C4BFbz6Vvxsq7D3lmhvFLn4jVA8+OidsM0
+YUrVMtWET/RkjEIbADbgRXxNUNo+jtQZDU9C1IiAdfk=
+-----END CERTIFICATE-----

authentik/enterprise/stages/mtls/tests/fixtures/cert_client.pem

@@ -0,0 +1,30 @@
+-----BEGIN CERTIFICATE-----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=
+-----END CERTIFICATE-----

authentik/enterprise/stages/mtls/tests/test_stage.py

@@ -0,0 +1,213 @@
+from unittest.mock import MagicMock, patch
+from urllib.parse import quote_plus
+
+from django.urls import reverse
+from guardian.shortcuts import assign_perm
+
+from authentik.core.models import User
+from authentik.core.tests.utils import create_test_brand, create_test_flow, create_test_user
+from authentik.crypto.models import CertificateKeyPair
+from authentik.enterprise.stages.mtls.models import (
+    CertAttributes,
+    MutualTLSStage,
+    TLSMode,
+    UserAttributes,
+)
+from authentik.enterprise.stages.mtls.stage import PLAN_CONTEXT_CERTIFICATE
+from authentik.flows.models import FlowDesignation, FlowStageBinding
+from authentik.flows.planner import PLAN_CONTEXT_PENDING_USER
+from authentik.flows.tests import FlowTestCase
+from authentik.lib.generators import generate_id
+from authentik.lib.tests.utils import load_fixture
+from authentik.outposts.models import Outpost, OutpostType
+from authentik.stages.prompt.stage import PLAN_CONTEXT_PROMPT
+
+
+class MTLSStageTests(FlowTestCase):
+
+    def setUp(self):
+        super().setUp()
+        self.flow = create_test_flow(FlowDesignation.AUTHENTICATION)
+        self.ca = CertificateKeyPair.objects.create(
+            name=generate_id(),
+            certificate_data=load_fixture("fixtures/ca.pem"),
+        )
+        self.stage = MutualTLSStage.objects.create(
+            name=generate_id(),
+            mode=TLSMode.REQUIRED,
+            cert_attribute=CertAttributes.COMMON_NAME,
+            user_attribute=UserAttributes.USERNAME,
+        )
+
+        self.stage.certificate_authorities.add(self.ca)
+        self.binding = FlowStageBinding.objects.create(target=self.flow, stage=self.stage, order=0)
+        self.client_cert = load_fixture("fixtures/cert_client.pem")
+        # User matching the certificate
+        User.objects.filter(username="client").delete()
+        self.cert_user = create_test_user(username="client")
+
+    def test_parse_xfcc(self):
+        """Test authentik Proxy/Envoy's XFCC format"""
+        with self.assertFlowFinishes() as plan:
+            res = self.client.get(
+                reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                headers={"X-Forwarded-Client-Cert": f"Cert={quote_plus(self.client_cert)}"},
+            )
+            self.assertEqual(res.status_code, 200)
+            self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+        self.assertEqual(plan().context[PLAN_CONTEXT_PENDING_USER], self.cert_user)
+
+    def test_parse_nginx(self):
+        """Test nginx's format"""
+        with self.assertFlowFinishes() as plan:
+            res = self.client.get(
+                reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                headers={"SSL-Client-Cert": quote_plus(self.client_cert)},
+            )
+            self.assertEqual(res.status_code, 200)
+            self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+        self.assertEqual(plan().context[PLAN_CONTEXT_PENDING_USER], self.cert_user)
+
+    def test_parse_traefik(self):
+        """Test traefik's format"""
+        with self.assertFlowFinishes() as plan:
+            res = self.client.get(
+                reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                headers={"X-Forwarded-TLS-Client-Cert": quote_plus(self.client_cert)},
+            )
+            self.assertEqual(res.status_code, 200)
+            self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+        self.assertEqual(plan().context[PLAN_CONTEXT_PENDING_USER], self.cert_user)
+
+    def test_parse_outpost_object(self):
+        """Test outposts's format"""
+        outpost = Outpost.objects.create(name=generate_id(), type=OutpostType.PROXY)
+        assign_perm("pass_outpost_certificate", outpost.user, self.stage)
+        with patch(
+            "authentik.root.middleware.ClientIPMiddleware.get_outpost_user",
+            MagicMock(return_value=outpost.user),
+        ):
+            with self.assertFlowFinishes() as plan:
+                res = self.client.get(
+                    reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                    headers={"X-Authentik-Outpost-Certificate": quote_plus(self.client_cert)},
+                )
+                self.assertEqual(res.status_code, 200)
+                self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+            self.assertEqual(plan().context[PLAN_CONTEXT_PENDING_USER], self.cert_user)
+
+    def test_parse_outpost_global(self):
+        """Test outposts's format"""
+        outpost = Outpost.objects.create(name=generate_id(), type=OutpostType.PROXY)
+        assign_perm("authentik_stages_mtls.pass_outpost_certificate", outpost.user)
+        with patch(
+            "authentik.root.middleware.ClientIPMiddleware.get_outpost_user",
+            MagicMock(return_value=outpost.user),
+        ):
+            with self.assertFlowFinishes() as plan:
+                res = self.client.get(
+                    reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                    headers={"X-Authentik-Outpost-Certificate": quote_plus(self.client_cert)},
+                )
+                self.assertEqual(res.status_code, 200)
+                self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+            self.assertEqual(plan().context[PLAN_CONTEXT_PENDING_USER], self.cert_user)
+
+    def test_parse_outpost_no_perm(self):
+        """Test outposts's format"""
+        outpost = Outpost.objects.create(name=generate_id(), type=OutpostType.PROXY)
+        with patch(
+            "authentik.root.middleware.ClientIPMiddleware.get_outpost_user",
+            MagicMock(return_value=outpost.user),
+        ):
+            res = self.client.get(
+                reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                headers={"X-Authentik-Outpost-Certificate": quote_plus(self.client_cert)},
+            )
+            self.assertEqual(res.status_code, 200)
+            self.assertStageResponse(res, self.flow, component="ak-stage-access-denied")
+
+    def test_auth_no_user(self):
+        """Test auth with no user"""
+        User.objects.filter(username="client").delete()
+        res = self.client.get(
+            reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+            headers={"X-Forwarded-TLS-Client-Cert": quote_plus(self.client_cert)},
+        )
+        self.assertEqual(res.status_code, 200)
+        self.assertStageResponse(res, self.flow, component="ak-stage-access-denied")
+
+    def test_brand_ca(self):
+        """Test using a CA from the brand"""
+        self.stage.certificate_authorities.clear()
+
+        brand = create_test_brand()
+        brand.client_certificates.add(self.ca)
+        with self.assertFlowFinishes() as plan:
+            res = self.client.get(
+                reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                headers={"X-Forwarded-TLS-Client-Cert": quote_plus(self.client_cert)},
+            )
+            self.assertEqual(res.status_code, 200)
+            self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+        self.assertEqual(plan().context[PLAN_CONTEXT_PENDING_USER], self.cert_user)
+
+    def test_no_ca_optional(self):
+        """Test using no CA Set"""
+        self.stage.mode = TLSMode.OPTIONAL
+        self.stage.certificate_authorities.clear()
+        self.stage.save()
+        res = self.client.get(
+            reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+            headers={"X-Forwarded-TLS-Client-Cert": quote_plus(self.client_cert)},
+        )
+        self.assertEqual(res.status_code, 200)
+        self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+
+    def test_no_ca_required(self):
+        """Test using no CA Set"""
+        self.stage.certificate_authorities.clear()
+        self.stage.save()
+        res = self.client.get(
+            reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+            headers={"X-Forwarded-TLS-Client-Cert": quote_plus(self.client_cert)},
+        )
+        self.assertEqual(res.status_code, 200)
+        self.assertStageResponse(res, self.flow, component="ak-stage-access-denied")
+
+    def test_no_cert_optional(self):
+        """Test using no cert Set"""
+        self.stage.mode = TLSMode.OPTIONAL
+        self.stage.save()
+        res = self.client.get(
+            reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+        )
+        self.assertEqual(res.status_code, 200)
+        self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+
+    def test_enroll(self):
+        """Test Enrollment flow"""
+        self.flow.designation = FlowDesignation.ENROLLMENT
+        self.flow.save()
+        with self.assertFlowFinishes() as plan:
+            res = self.client.get(
+                reverse("authentik_api:flow-executor", kwargs={"flow_slug": self.flow.slug}),
+                headers={"X-Forwarded-TLS-Client-Cert": quote_plus(self.client_cert)},
+            )
+            self.assertEqual(res.status_code, 200)
+            self.assertStageRedirects(res, reverse("authentik_core:root-redirect"))
+        self.assertEqual(plan().context[PLAN_CONTEXT_PROMPT], {"email": None, "name": "client"})
+        self.assertEqual(
+            plan().context[PLAN_CONTEXT_CERTIFICATE],
+            {
+                "fingerprint_sha1": (
+                    "08:d4:a4:79:25:ca:c3:51:28:88:bb:30:c2:96:c3:44:5a:eb:18:07:84:ca:b4:75:27:74:61:19:8a:6a:af:fc"
+                ),
+                "fingerprint_sha256": (
+                    "08:d4:a4:79:25:ca:c3:51:28:88:bb:30:c2:96:c3:44:5a:eb:18:07:84:ca:b4:75:27:74:61:19:8a:6a:af:fc"
+                ),
+                "issuer": "OU=Self-signed,O=authentik,CN=authentik Test CA",
+                "serial_number": "630532384467334865093173111400266136879266564943",
+                "subject": "CN=client",
+            },
+        )

authentik/enterprise/stages/mtls/urls.py

@@ -0,0 +1,5 @@
+"""API URLs"""
+
+from authentik.enterprise.stages.mtls.api import MutualTLSStageViewSet
+
+api_urlpatterns = [("stages/mtls", MutualTLSStageViewSet)]

authentik/flows/tests/__init__.py

@@ -1,7 +1,10 @@
 """Test helpers"""
 
+from collections.abc import Callable, Generator
+from contextlib import contextmanager
 from json import loads
 from typing import Any
+from unittest.mock import MagicMock, patch
 
 from django.http.response import HttpResponse
 from django.urls.base import reverse
@@ -9,6 +12,8 @@ from rest_framework.test import APITestCase
 
 from authentik.core.models import User
 from authentik.flows.models import Flow
+from authentik.flows.planner import FlowPlan
+from authentik.flows.views.executor import SESSION_KEY_PLAN
 
 
 class FlowTestCase(APITestCase):
@@ -44,3 +49,12 @@ class FlowTestCase(APITestCase):
     def assertStageRedirects(self, response: HttpResponse, to: str) -> dict[str, Any]:
         """Wrapper around assertStageResponse that checks for a redirect"""
         return self.assertStageResponse(response, component="xak-flow-redirect", to=to)
+
+    @contextmanager
+    def assertFlowFinishes(self) -> Generator[Callable[[], FlowPlan]]:
+        """Capture the flow plan before the flow finishes and return it"""
+        try:
+            with patch("authentik.flows.views.executor.FlowExecutorView.cancel", MagicMock()):
+                yield lambda: self.client.session.get(SESSION_KEY_PLAN)
+        finally:
+            pass

blueprints/schema.json

@@ -3921,6 +3921,46 @@
                             }
                         }
                     },
+                    {
+                        "type": "object",
+                        "required": [
+                            "model",
+                            "identifiers"
+                        ],
+                        "properties": {
+                            "model": {
+                                "const": "authentik_stages_mtls.mutualtlsstage"
+                            },
+                            "id": {
+                                "type": "string"
+                            },
+                            "state": {
+                                "type": "string",
+                                "enum": [
+                                    "absent",
+                                    "present",
+                                    "created",
+                                    "must_created"
+                                ],
+                                "default": "present"
+                            },
+                            "conditions": {
+                                "type": "array",
+                                "items": {
+                                    "type": "boolean"
+                                }
+                            },
+                            "permissions": {
+                                "$ref": "#/$defs/model_authentik_stages_mtls.mutualtlsstage_permissions"
+                            },
+                            "attrs": {
+                                "$ref": "#/$defs/model_authentik_stages_mtls.mutualtlsstage"
+                            },
+                            "identifiers": {
+                                "$ref": "#/$defs/model_authentik_stages_mtls.mutualtlsstage"
+                            }
+                        }
+                    },
                     {
                         "type": "object",
                         "required": [
@@ -4867,6 +4907,7 @@
                         "authentik.enterprise.providers.microsoft_entra",
                         "authentik.enterprise.providers.ssf",
                         "authentik.enterprise.stages.authenticator_endpoint_gdtc",
+                        "authentik.enterprise.stages.mtls",
                         "authentik.enterprise.stages.source",
                         "authentik.events"
                     ],
@@ -4977,6 +5018,7 @@
                         "authentik_providers_microsoft_entra.microsoftentraprovidermapping",
                         "authentik_providers_ssf.ssfprovider",
                         "authentik_stages_authenticator_endpoint_gdtc.authenticatorendpointgdtcstage",
+                        "authentik_stages_mtls.mutualtlsstage",
                         "authentik_stages_source.sourcestage",
                         "authentik_events.event",
                         "authentik_events.notificationtransport",
@@ -7477,6 +7519,11 @@
                             "authentik_stages_invitation.delete_invitationstage",
                             "authentik_stages_invitation.view_invitation",
                             "authentik_stages_invitation.view_invitationstage",
+                            "authentik_stages_mtls.add_mutualtlsstage",
+                            "authentik_stages_mtls.change_mutualtlsstage",
+                            "authentik_stages_mtls.delete_mutualtlsstage",
+                            "authentik_stages_mtls.pass_outpost_certificate",
+                            "authentik_stages_mtls.view_mutualtlsstage",
                             "authentik_stages_password.add_passwordstage",
                             "authentik_stages_password.change_passwordstage",
                             "authentik_stages_password.delete_passwordstage",
@@ -13422,6 +13469,16 @@
                     "title": "Web certificate",
                     "description": "Web Certificate used by the authentik Core webserver."
                 },
+                "client_certificates": {
+                    "type": "array",
+                    "items": {
+                        "type": "string",
+                        "format": "uuid",
+                        "description": "Certificates used for client authentication."
+                    },
+                    "title": "Client certificates",
+                    "description": "Certificates used for client authentication."
+                },
                 "attributes": {
                     "type": "object",
                     "additionalProperties": true,
@@ -14185,6 +14242,11 @@
                             "authentik_stages_invitation.delete_invitationstage",
                             "authentik_stages_invitation.view_invitation",
                             "authentik_stages_invitation.view_invitationstage",
+                            "authentik_stages_mtls.add_mutualtlsstage",
+                            "authentik_stages_mtls.change_mutualtlsstage",
+                            "authentik_stages_mtls.delete_mutualtlsstage",
+                            "authentik_stages_mtls.pass_outpost_certificate",
+                            "authentik_stages_mtls.view_mutualtlsstage",
                             "authentik_stages_password.add_passwordstage",
                             "authentik_stages_password.change_passwordstage",
                             "authentik_stages_password.delete_passwordstage",
@@ -15088,6 +15150,161 @@
                 }
             }
         },
+        "model_authentik_stages_mtls.mutualtlsstage": {
+            "type": "object",
+            "properties": {
+                "name": {
+                    "type": "string",
+                    "minLength": 1,
+                    "title": "Name"
+                },
+                "flow_set": {
+                    "type": "array",
+                    "items": {
+                        "type": "object",
+                        "properties": {
+                            "name": {
+                                "type": "string",
+                                "minLength": 1,
+                                "title": "Name"
+                            },
+                            "slug": {
+                                "type": "string",
+                                "maxLength": 50,
+                                "minLength": 1,
+                                "pattern": "^[-a-zA-Z0-9_]+$",
+                                "title": "Slug",
+                                "description": "Visible in the URL."
+                            },
+                            "title": {
+                                "type": "string",
+                                "minLength": 1,
+                                "title": "Title",
+                                "description": "Shown as the Title in Flow pages."
+                            },
+                            "designation": {
+                                "type": "string",
+                                "enum": [
+                                    "authentication",
+                                    "authorization",
+                                    "invalidation",
+                                    "enrollment",
+                                    "unenrollment",
+                                    "recovery",
+                                    "stage_configuration"
+                                ],
+                                "title": "Designation",
+                                "description": "Decides what this Flow is used for. For example, the Authentication flow is redirect to when an un-authenticated user visits authentik."
+                            },
+                            "policy_engine_mode": {
+                                "type": "string",
+                                "enum": [
+                                    "all",
+                                    "any"
+                                ],
+                                "title": "Policy engine mode"
+                            },
+                            "compatibility_mode": {
+                                "type": "boolean",
+                                "title": "Compatibility mode",
+                                "description": "Enable compatibility mode, increases compatibility with password managers on mobile devices."
+                            },
+                            "layout": {
+                                "type": "string",
+                                "enum": [
+                                    "stacked",
+                                    "content_left",
+                                    "content_right",
+                                    "sidebar_left",
+                                    "sidebar_right"
+                                ],
+                                "title": "Layout"
+                            },
+                            "denied_action": {
+                                "type": "string",
+                                "enum": [
+                                    "message_continue",
+                                    "message",
+                                    "continue"
+                                ],
+                                "title": "Denied action",
+                                "description": "Configure what should happen when a flow denies access to a user."
+                            }
+                        },
+                        "required": [
+                            "name",
+                            "slug",
+                            "title",
+                            "designation"
+                        ]
+                    },
+                    "title": "Flow set"
+                },
+                "mode": {
+                    "type": "string",
+                    "enum": [
+                        "optional",
+                        "required"
+                    ],
+                    "title": "Mode"
+                },
+                "certificate_authorities": {
+                    "type": "array",
+                    "items": {
+                        "type": "string",
+                        "format": "uuid",
+                        "description": "Configure certificate authorities to validate the certificate against. This option has a higher priority than the `client_certificate` option on `Brand`."
+                    },
+                    "title": "Certificate authorities",
+                    "description": "Configure certificate authorities to validate the certificate against. This option has a higher priority than the `client_certificate` option on `Brand`."
+                },
+                "cert_attribute": {
+                    "type": "string",
+                    "enum": [
+                        "subject",
+                        "common_name",
+                        "email"
+                    ],
+                    "title": "Cert attribute"
+                },
+                "user_attribute": {
+                    "type": "string",
+                    "enum": [
+                        "username",
+                        "email"
+                    ],
+                    "title": "User attribute"
+                }
+            },
+            "required": []
+        },
+        "model_authentik_stages_mtls.mutualtlsstage_permissions": {
+            "type": "array",
+            "items": {
+                "type": "object",
+                "required": [
+                    "permission"
+                ],
+                "properties": {
+                    "permission": {
+                        "type": "string",
+                        "enum": [
+                            "pass_outpost_certificate",
+                            "add_mutualtlsstage",
+                            "change_mutualtlsstage",
+                            "delete_mutualtlsstage",
+                            "view_mutualtlsstage"
+                        ]
+                    },
+                    "user": {
+                        "type": "integer"
+                    },
+                    "role": {
+                        "type": "string"
+                    }
+                }
+            }
+        },
         "model_authentik_stages_source.sourcestage": {
             "type": "object",
             "properties": {

cmd/server/server.go

@@ -19,7 +19,6 @@ import (
 	sentryutils "goauthentik.io/internal/utils/sentry"
 	webutils "goauthentik.io/internal/utils/web"
 	"goauthentik.io/internal/web"
-	"goauthentik.io/internal/web/brand_tls"
 )
 
 var rootCmd = &cobra.Command{
@@ -67,12 +66,12 @@ var rootCmd = &cobra.Command{
 		}
 
 		ws := web.NewWebServer()
-		ws.Core().HealthyCallback = func() {
+		ws.Core().AddHealthyCallback(func() {
 			if config.Get().Outposts.DisableEmbeddedOutpost {
 				return
 			}
 			go attemptProxyStart(ws, u)
-		}
+		})
 		ws.Start()
 		<-ex
 		l.Info("shutting down webserver")
@@ -95,13 +94,8 @@ func attemptProxyStart(ws *web.WebServer, u *url.URL) {
 			}
 			continue
 		}
-		// Init brand_tls here too since it requires an API Client,
-		// so we just reuse the same one as the outpost uses
-		tw := brand_tls.NewWatcher(ac.Client)
-		go tw.Start()
-		ws.BrandTLS = tw
 		ac.AddRefreshHandler(func() {
-			tw.Check()
+			ws.BrandTLS.Check()
 		})
 
 		srv := proxyv2.NewProxyServer(ac)

internal/constants/constants.go

@@ -21,10 +21,14 @@ func FullVersion() string {
 	return ver
 }
 
-func OutpostUserAgent() string {
+func UserAgentOutpost() string {
 	return fmt.Sprintf("goauthentik.io/outpost/%s", FullVersion())
 }
 
+func UserAgentIPC() string {
+	return fmt.Sprintf("goauthentik.io/ipc/%s", FullVersion())
+}
+
 func UserAgent() string {
 	return fmt.Sprintf("authentik@%s", FullVersion())
 }

internal/gounicorn/gounicorn.go

@@ -18,8 +18,8 @@ import (
 )
 
 type GoUnicorn struct {
-	Healthcheck     func() bool
-	HealthyCallback func()
+	Healthcheck      func() bool
+	healthyCallbacks []func()
 
 	log     *log.Entry
 	p       *exec.Cmd
@@ -32,12 +32,12 @@ type GoUnicorn struct {
 func New(healthcheck func() bool) *GoUnicorn {
 	logger := log.WithField("logger", "authentik.router.unicorn")
 	g := &GoUnicorn{
-		Healthcheck:     healthcheck,
-		log:             logger,
-		started:         false,
-		killed:          false,
-		alive:           false,
-		HealthyCallback: func() {},
+		Healthcheck:      healthcheck,
+		log:              logger,
+		started:          false,
+		killed:           false,
+		alive:            false,
+		healthyCallbacks: []func(){},
 	}
 	g.initCmd()
 	c := make(chan os.Signal, 1)
@@ -79,6 +79,10 @@ func (g *GoUnicorn) initCmd() {
 	g.p.Stderr = os.Stderr
 }
 
+func (g *GoUnicorn) AddHealthyCallback(cb func()) {
+	g.healthyCallbacks = append(g.healthyCallbacks, cb)
+}
+
 func (g *GoUnicorn) IsRunning() bool {
 	return g.alive
 }
@@ -101,7 +105,9 @@ func (g *GoUnicorn) healthcheck() {
 		if g.Healthcheck() {
 			g.alive = true
 			g.log.Debug("backend is alive, backing off with healthchecks")
-			g.HealthyCallback()
+			for _, cb := range g.healthyCallbacks {
+				cb()
+			}
 			break
 		}
 		g.log.Debug("backend not alive yet")

internal/outpost/ak/api.go

@@ -62,7 +62,7 @@ func NewAPIController(akURL url.URL, token string) *APIController {
 	apiConfig.Scheme = akURL.Scheme
 	apiConfig.HTTPClient = &http.Client{
 		Transport: web.NewUserAgentTransport(
-			constants.OutpostUserAgent(),
+			constants.UserAgentOutpost(),
 			web.NewTracingTransport(
 				rsp.Context(),
 				GetTLSTransport(),

internal/outpost/ak/api_ws.go

@@ -38,7 +38,7 @@ func (ac *APIController) initWS(akURL url.URL, outpostUUID string) error {
 
 	header := http.Header{
 		"Authorization": []string{authHeader},
-		"User-Agent":    []string{constants.OutpostUserAgent()},
+		"User-Agent":    []string{constants.UserAgentOutpost()},
 	}
 
 	dialer := websocket.Dialer{

internal/outpost/ak/crypto.go

@@ -3,6 +3,8 @@ package ak
 import (
 	"context"
 	"crypto/tls"
+	"crypto/x509"
+	"encoding/pem"
 
 	log "github.com/sirupsen/logrus"
 	"goauthentik.io/api/v3"
@@ -67,16 +69,34 @@ func (cs *CryptoStore) Fetch(uuid string) error {
 		return err
 	}
 
-	x509cert, err := tls.X509KeyPair([]byte(cert.Data), []byte(key.Data))
-	if err != nil {
-		return err
+	var tcert tls.Certificate
+	if key.Data != "" {
+		x509cert, err := tls.X509KeyPair([]byte(cert.Data), []byte(key.Data))
+		if err != nil {
+			return err
+		}
+		tcert = x509cert
+	} else {
+		p, _ := pem.Decode([]byte(cert.Data))
+		x509cert, err := x509.ParseCertificate(p.Bytes)
+		if err != nil {
+			return err
+		}
+		tcert = tls.Certificate{
+			Certificate: [][]byte{x509cert.Raw},
+			Leaf:        x509cert,
+		}
 	}
-	cs.certificates[uuid] = &x509cert
+	cs.certificates[uuid] = &tcert
 	cs.fingerprints[uuid] = cfp
 	return nil
 }
 
 func (cs *CryptoStore) Get(uuid string) *tls.Certificate {
+	c, ok := cs.certificates[uuid]
+	if ok {
+		return c
+	}
 	err := cs.Fetch(uuid)
 	if err != nil {
 		cs.log.WithError(err).Warning("failed to fetch certificate")

internal/outpost/ak/global.go

@@ -55,7 +55,7 @@ func doGlobalSetup(outpost api.Outpost, globalConfig *api.Config) {
 			EnableTracing: true,
 			TracesSampler: sentryutils.SamplerFunc(float64(globalConfig.ErrorReporting.TracesSampleRate)),
 			Release:       fmt.Sprintf("authentik@%s", constants.VERSION),
-			HTTPTransport: webutils.NewUserAgentTransport(constants.OutpostUserAgent(), http.DefaultTransport),
+			HTTPTransport: webutils.NewUserAgentTransport(constants.UserAgentOutpost(), http.DefaultTransport),
 			IgnoreErrors: []string{
 				http.ErrAbortHandler.Error(),
 			},

internal/outpost/flow/executor.go

@@ -61,7 +61,7 @@ func NewFlowExecutor(ctx context.Context, flowSlug string, refConfig *api.Config
 		l.WithError(err).Warning("Failed to create cookiejar")
 		panic(err)
 	}
-	transport := web.NewUserAgentTransport(constants.OutpostUserAgent(), web.NewTracingTransport(rsp.Context(), ak.GetTLSTransport()))
+	transport := web.NewUserAgentTransport(constants.UserAgentOutpost(), web.NewTracingTransport(rsp.Context(), ak.GetTLSTransport()))
 	fe := &FlowExecutor{
 		Params:    url.Values{},
 		Answers:   make(map[StageComponent]string),

internal/outpost/proxyv2/application/mode_common.go

@@ -52,7 +52,7 @@ func (a *Application) addHeaders(headers http.Header, c *Claims) {
 	headers.Set("X-authentik-meta-outpost", a.outpostName)
 	headers.Set("X-authentik-meta-provider", a.proxyConfig.Name)
 	headers.Set("X-authentik-meta-app", a.proxyConfig.AssignedApplicationSlug)
-	headers.Set("X-authentik-meta-version", constants.OutpostUserAgent())
+	headers.Set("X-authentik-meta-version", constants.UserAgentOutpost())
 
 	if c.Proxy == nil {
 		return

internal/outpost/proxyv2/refresh.go

@@ -31,7 +31,7 @@ func (ps *ProxyServer) Refresh() error {
 		ua := fmt.Sprintf(" (provider=%s)", provider.Name)
 		hc := &http.Client{
 			Transport: web.NewUserAgentTransport(
-				constants.OutpostUserAgent()+ua,
+				constants.UserAgentOutpost()+ua,
 				web.NewTracingTransport(
 					rsp.Context(),
 					ak.GetTLSTransport(),

internal/outpost/rac/connection/connection.go

@@ -61,7 +61,7 @@ func (c *Connection) initSocket(forChannel string) error {
 
 	header := http.Header{
 		"Authorization": []string{authHeader},
-		"User-Agent":    []string{constants.OutpostUserAgent()},
+		"User-Agent":    []string{constants.UserAgentOutpost()},
 	}
 
 	dialer := websocket.Dialer{

internal/utils/web/http_forwarded.go

@@ -1,6 +1,7 @@
 package web
 
 import (
+	"context"
 	"net"
 	"net/http"
 
@@ -9,6 +10,14 @@ import (
 	"goauthentik.io/internal/config"
 )
 
+type allowedProxyRequestContext string
+
+const allowedProxyRequest allowedProxyRequestContext = ""
+
+func IsRequestFromTrustedProxy(r *http.Request) bool {
+	return r.Context().Value(allowedProxyRequest) != nil
+}
+
 // ProxyHeaders Set proxy headers like X-Forwarded-For and such, but only if the direct connection
 // comes from a client that's in a list of trusted CIDRs
 func ProxyHeaders() func(http.Handler) http.Handler {
@@ -20,7 +29,6 @@ func ProxyHeaders() func(http.Handler) http.Handler {
 		}
 		nets = append(nets, cidr)
 	}
-	ph := handlers.ProxyHeaders
 	return func(h http.Handler) http.Handler {
 		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 			host, _, err := net.SplitHostPort(r.RemoteAddr)
@@ -30,7 +38,8 @@ func ProxyHeaders() func(http.Handler) http.Handler {
 				for _, allowedCidr := range nets {
 					if remoteAddr != nil && allowedCidr.Contains(remoteAddr) {
 						log.WithField("remoteAddr", remoteAddr).WithField("cidr", allowedCidr.String()).Trace("Setting proxy headers")
-						ph(h).ServeHTTP(w, r)
+						rr := r.WithContext(context.WithValue(r.Context(), allowedProxyRequest, true))
+						handlers.ProxyHeaders(h).ServeHTTP(w, rr)
 						return
 					}
 				}

internal/web/brand_tls/brand_tls.go

@@ -3,6 +3,7 @@ package brand_tls
 import (
 	"context"
 	"crypto/tls"
+	"crypto/x509"
 	"strings"
 	"time"
 
@@ -56,22 +57,37 @@ func (w *Watcher) Check() {
 		return
 	}
 	for _, b := range brands {
-		kp := b.WebCertificate.Get()
-		if kp == nil {
-			continue
+		kp := b.GetWebCertificate()
+		if kp != "" {
+			err := w.cs.AddKeypair(kp)
+			if err != nil {
+				w.log.WithError(err).WithField("kp", kp).Warning("failed to add web certificate")
+			}
 		}
-		err := w.cs.AddKeypair(*kp)
-		if err != nil {
-			w.log.WithError(err).Warning("failed to add certificate")
+		for _, crt := range b.GetClientCertificates() {
+			if crt != "" {
+				err := w.cs.AddKeypair(crt)
+				if err != nil {
+					w.log.WithError(err).WithField("kp", kp).Warning("failed to add client certificate")
+				}
+			}
 		}
 	}
 	w.brands = brands
 }
 
-func (w *Watcher) GetCertificate(ch *tls.ClientHelloInfo) (*tls.Certificate, error) {
+type CertificateConfig struct {
+	Web    *tls.Certificate
+	Client *x509.CertPool
+}
+
+func (w *Watcher) GetCertificate(ch *tls.ClientHelloInfo) *CertificateConfig {
 	var bestSelection *api.Brand
+	config := CertificateConfig{
+		Web: w.fallback,
+	}
 	for _, t := range w.brands {
-		if t.WebCertificate.Get() == nil {
+		if !t.WebCertificate.IsSet() && len(t.GetClientCertificates()) < 1 {
 			continue
 		}
 		if *t.Default {
@@ -82,11 +98,20 @@ func (w *Watcher) GetCertificate(ch *tls.ClientHelloInfo) (*tls.Certificate, err
 		}
 	}
 	if bestSelection == nil {
-		return w.fallback, nil
+		return &config
 	}
-	cert := w.cs.Get(bestSelection.GetWebCertificate())
-	if cert == nil {
-		return w.fallback, nil
+	if bestSelection.GetWebCertificate() != "" {
+		if cert := w.cs.Get(bestSelection.GetWebCertificate()); cert != nil {
+			config.Web = cert
+		}
 	}
-	return cert, nil
+	if len(bestSelection.GetClientCertificates()) > 0 {
+		config.Client = x509.NewCertPool()
+		for _, kp := range bestSelection.GetClientCertificates() {
+			if cert := w.cs.Get(kp); cert != nil {
+				config.Client.AddCert(cert.Leaf)
+			}
+		}
+	}
+	return &config
 }

internal/web/metrics.go

@@ -1,15 +1,11 @@
 package web
 
 import (
-	"encoding/base64"
 	"fmt"
 	"io"
 	"net/http"
-	"os"
-	"path"
 
 	"github.com/gorilla/mux"
-	"github.com/gorilla/securecookie"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
@@ -18,8 +14,6 @@ import (
 	"goauthentik.io/internal/utils/sentry"
 )
 
-const MetricsKeyFile = "authentik-core-metrics.key"
-
 var Requests = promauto.NewHistogramVec(prometheus.HistogramOpts{
 	Name: "authentik_main_request_duration_seconds",
 	Help: "API request latencies in seconds",
@@ -27,14 +21,6 @@ var Requests = promauto.NewHistogramVec(prometheus.HistogramOpts{
 
 func (ws *WebServer) runMetricsServer() {
 	l := log.WithField("logger", "authentik.router.metrics")
-	tmp := os.TempDir()
-	key := base64.StdEncoding.EncodeToString(securecookie.GenerateRandomKey(64))
-	keyPath := path.Join(tmp, MetricsKeyFile)
-	err := os.WriteFile(keyPath, []byte(key), 0o600)
-	if err != nil {
-		l.WithError(err).Warning("failed to save metrics key")
-		return
-	}
 
 	m := mux.NewRouter()
 	m.Use(sentry.SentryNoSampleMiddleware)
@@ -51,7 +37,7 @@ func (ws *WebServer) runMetricsServer() {
 			l.WithError(err).Warning("failed to get upstream metrics")
 			return
 		}
-		re.Header.Set("Authorization", fmt.Sprintf("Bearer %s", key))
+		re.Header.Set("Authorization", fmt.Sprintf("Bearer %s", ws.metricsKey))
 		res, err := ws.upstreamHttpClient().Do(re)
 		if err != nil {
 			l.WithError(err).Warning("failed to get upstream metrics")
@@ -64,13 +50,9 @@ func (ws *WebServer) runMetricsServer() {
 		}
 	})
 	l.WithField("listen", config.Get().Listen.Metrics).Info("Starting Metrics server")
-	err = http.ListenAndServe(config.Get().Listen.Metrics, m)
+	err := http.ListenAndServe(config.Get().Listen.Metrics, m)
 	if err != nil {
 		l.WithError(err).Warning("Failed to start metrics server")
 	}
 	l.WithField("listen", config.Get().Listen.Metrics).Info("Stopping Metrics server")
-	err = os.Remove(keyPath)
-	if err != nil {
-		l.WithError(err).Warning("failed to remove metrics key file")
-	}
 }

internal/web/proxy.go

@@ -2,21 +2,29 @@ package web
 
 import (
 	"encoding/json"
+	"encoding/pem"
 	"errors"
 	"fmt"
 	"net/http"
 	"net/http/httputil"
+	"net/url"
+	"strings"
 	"time"
 
 	"github.com/prometheus/client_golang/prometheus"
 	"goauthentik.io/internal/config"
 	"goauthentik.io/internal/utils/sentry"
+	"goauthentik.io/internal/utils/web"
 )
 
 var (
 	ErrAuthentikStarting = errors.New("authentik starting")
 )
 
+const (
+	maxBodyBytes = 32 * 1024 * 1024
+)
+
 func (ws *WebServer) configureProxy() {
 	// Reverse proxy to the application server
 	director := func(req *http.Request) {
@@ -26,8 +34,25 @@ func (ws *WebServer) configureProxy() {
 			// explicitly disable User-Agent so it's not set to default value
 			req.Header.Set("User-Agent", "")
 		}
+		if !web.IsRequestFromTrustedProxy(req) {
+			// If the request isn't coming from a trusted proxy, delete MTLS headers
+			req.Header.Del("SSL-Client-Cert")             // nginx-ingress
+			req.Header.Del("X-Forwarded-TLS-Client-Cert") // traefik
+			req.Header.Del("X-Forwarded-Client-Cert")     // envoy
+		}
 		if req.TLS != nil {
 			req.Header.Set("X-Forwarded-Proto", "https")
+			if len(req.TLS.PeerCertificates) > 0 {
+				pems := make([]string, len(req.TLS.PeerCertificates))
+				for i, crt := range req.TLS.PeerCertificates {
+					pem := pem.EncodeToMemory(&pem.Block{
+						Type:  "CERTIFICATE",
+						Bytes: crt.Raw,
+					})
+					pems[i] = "Cert=" + url.QueryEscape(string(pem))
+				}
+				req.Header.Set("X-Forwarded-Client-Cert", strings.Join(pems, ","))
+			}
 		}
 		ws.log.WithField("url", req.URL.String()).WithField("headers", req.Header).Trace("tracing request to backend")
 	}
@@ -57,7 +82,7 @@ func (ws *WebServer) configureProxy() {
 		Requests.With(prometheus.Labels{
 			"dest": "core",
 		}).Observe(float64(elapsed) / float64(time.Second))
-		r.Body = http.MaxBytesReader(rw, r.Body, 32*1024*1024)
+		r.Body = http.MaxBytesReader(rw, r.Body, maxBodyBytes)
 		rp.ServeHTTP(rw, r)
 	}))
 }

internal/web/web.go

@@ -2,6 +2,7 @@ package web
 
 import (
 	"context"
+	"encoding/base64"
 	"errors"
 	"fmt"
 	"net"
@@ -13,17 +14,27 @@ import (
 
 	"github.com/gorilla/handlers"
 	"github.com/gorilla/mux"
+	"github.com/gorilla/securecookie"
 	"github.com/pires/go-proxyproto"
 	log "github.com/sirupsen/logrus"
 
+	"goauthentik.io/api/v3"
 	"goauthentik.io/internal/config"
+	"goauthentik.io/internal/constants"
 	"goauthentik.io/internal/gounicorn"
+	"goauthentik.io/internal/outpost/ak"
 	"goauthentik.io/internal/outpost/proxyv2"
 	"goauthentik.io/internal/utils"
 	"goauthentik.io/internal/utils/web"
 	"goauthentik.io/internal/web/brand_tls"
 )
 
+const (
+	IPCKeyFile     = "authentik-core-ipc.key"
+	MetricsKeyFile = "authentik-core-metrics.key"
+	UnixSocketName = "authentik-core.sock"
+)
+
 type WebServer struct {
 	Bind    string
 	BindTLS bool
@@ -40,9 +51,10 @@ type WebServer struct {
 	log            *log.Entry
 	upstreamClient *http.Client
 	upstreamURL    *url.URL
-}
 
-const UnixSocketName = "authentik-core.sock"
+	metricsKey string
+	ipcKey     string
+}
 
 func NewWebServer() *WebServer {
 	l := log.WithField("logger", "authentik.router")
@@ -76,7 +88,7 @@ func NewWebServer() *WebServer {
 		mainRouter:     mainHandler,
 		loggingRouter:  loggingHandler,
 		log:            l,
-		gunicornReady:  true,
+		gunicornReady:  false,
 		upstreamClient: upstreamClient,
 		upstreamURL:    u,
 	}
@@ -103,7 +115,59 @@ func NewWebServer() *WebServer {
 	return ws
 }
 
+func (ws *WebServer) prepareKeys() {
+	tmp := os.TempDir()
+	key := base64.StdEncoding.EncodeToString(securecookie.GenerateRandomKey(64))
+	err := os.WriteFile(path.Join(tmp, MetricsKeyFile), []byte(key), 0o600)
+	if err != nil {
+		ws.log.WithError(err).Warning("failed to save metrics key")
+		return
+	}
+	ws.metricsKey = key
+
+	key = base64.StdEncoding.EncodeToString(securecookie.GenerateRandomKey(64))
+	err = os.WriteFile(path.Join(tmp, IPCKeyFile), []byte(key), 0o600)
+	if err != nil {
+		ws.log.WithError(err).Warning("failed to save ipc key")
+		return
+	}
+	ws.ipcKey = key
+}
+
 func (ws *WebServer) Start() {
+	ws.prepareKeys()
+
+	u, err := url.Parse(fmt.Sprintf("http://%s%s", config.Get().Listen.HTTP, config.Get().Web.Path))
+	if err != nil {
+		panic(err)
+	}
+	apiConfig := api.NewConfiguration()
+	apiConfig.Host = u.Host
+	apiConfig.Scheme = u.Scheme
+	apiConfig.HTTPClient = &http.Client{
+		Transport: web.NewUserAgentTransport(
+			constants.UserAgentIPC(),
+			ak.GetTLSTransport(),
+		),
+	}
+	apiConfig.Servers = api.ServerConfigurations{
+		{
+			URL: fmt.Sprintf("%sapi/v3", u.Path),
+		},
+	}
+	apiConfig.AddDefaultHeader("Authorization", fmt.Sprintf("Bearer %s", ws.ipcKey))
+
+	// create the API client, with the transport
+	apiClient := api.NewAPIClient(apiConfig)
+
+	// Init brand_tls here too since it requires an API Client,
+	// so we just reuse the same one as the outpost uses
+	tw := brand_tls.NewWatcher(apiClient)
+	ws.BrandTLS = tw
+	ws.g.AddHealthyCallback(func() {
+		go tw.Start()
+	})
+
 	go ws.runMetricsServer()
 	go ws.attemptStartBackend()
 	go ws.listenPlain()
@@ -112,23 +176,23 @@ func (ws *WebServer) Start() {
 
 func (ws *WebServer) attemptStartBackend() {
 	for {
-		if !ws.gunicornReady {
+		if ws.gunicornReady {
 			return
 		}
 		err := ws.g.Start()
-		log.WithField("logger", "authentik.router").WithError(err).Warning("gunicorn process died, restarting")
+		ws.log.WithError(err).Warning("gunicorn process died, restarting")
 		if err != nil {
-			log.WithField("logger", "authentik.router").WithError(err).Error("gunicorn failed to start, restarting")
+			ws.log.WithError(err).Error("gunicorn failed to start, restarting")
 			continue
 		}
 		failedChecks := 0
 		for range time.NewTicker(30 * time.Second).C {
 			if !ws.g.IsRunning() {
-				log.WithField("logger", "authentik.router").Warningf("gunicorn process failed healthcheck %d times", failedChecks)
+				ws.log.Warningf("gunicorn process failed healthcheck %d times", failedChecks)
 				failedChecks += 1
 			}
 			if failedChecks >= 3 {
-				log.WithField("logger", "authentik.router").WithError(err).Error("gunicorn process failed healthcheck three times, restarting")
+				ws.log.WithError(err).Error("gunicorn process failed healthcheck three times, restarting")
 				break
 			}
 		}
@@ -146,6 +210,15 @@ func (ws *WebServer) upstreamHttpClient() *http.Client {
 func (ws *WebServer) Shutdown() {
 	ws.log.Info("shutting down gunicorn")
 	ws.g.Kill()
+	tmp := os.TempDir()
+	err := os.Remove(path.Join(tmp, MetricsKeyFile))
+	if err != nil {
+		ws.log.WithError(err).Warning("failed to remove metrics key file")
+	}
+	err = os.Remove(path.Join(tmp, IPCKeyFile))
+	if err != nil {
+		ws.log.WithError(err).Warning("failed to remove ipc key file")
+	}
 	ws.stop <- struct{}{}
 }
 

internal/web/web_tls.go

@@ -12,40 +12,57 @@ import (
 	"goauthentik.io/internal/utils/web"
 )
 
-func (ws *WebServer) GetCertificate() func(ch *tls.ClientHelloInfo) (*tls.Certificate, error) {
-	cert, err := crypto.GenerateSelfSignedCert()
+func (ws *WebServer) GetCertificate() func(ch *tls.ClientHelloInfo) (*tls.Config, error) {
+	fallback, err := crypto.GenerateSelfSignedCert()
 	if err != nil {
 		ws.log.WithError(err).Error("failed to generate default cert")
 	}
-	return func(ch *tls.ClientHelloInfo) (*tls.Certificate, error) {
+	return func(ch *tls.ClientHelloInfo) (*tls.Config, error) {
+		cfg := utils.GetTLSConfig()
 		if ch.ServerName == "" {
-			return &cert, nil
+			cfg.Certificates = []tls.Certificate{fallback}
+			return cfg, nil
 		}
 		if ws.ProxyServer != nil {
 			appCert := ws.ProxyServer.GetCertificate(ch.ServerName)
 			if appCert != nil {
-				return appCert, nil
+				cfg.Certificates = []tls.Certificate{*appCert}
+				return cfg, nil
 			}
 		}
 		if ws.BrandTLS != nil {
-			return ws.BrandTLS.GetCertificate(ch)
+			bcert := ws.BrandTLS.GetCertificate(ch)
+			cfg.Certificates = []tls.Certificate{*bcert.Web}
+			ws.log.Trace("using brand web Certificate")
+			if bcert.Client != nil {
+				cfg.ClientCAs = bcert.Client
+				cfg.ClientAuth = tls.RequestClientCert
+				ws.log.Trace("using brand client Certificate")
+			}
+			return cfg, nil
 		}
 		ws.log.Trace("using default, self-signed certificate")
-		return &cert, nil
+		cfg.Certificates = []tls.Certificate{fallback}
+		return cfg, nil
 	}
 }
 
 // ServeHTTPS constructs a net.Listener and starts handling HTTPS requests
 func (ws *WebServer) listenTLS() {
 	tlsConfig := utils.GetTLSConfig()
-	tlsConfig.GetCertificate = ws.GetCertificate()
+	tlsConfig.GetConfigForClient = ws.GetCertificate()
 
 	ln, err := net.Listen("tcp", config.Get().Listen.HTTPS)
 	if err != nil {
 		ws.log.WithError(err).Warning("failed to listen (TLS)")
 		return
 	}
-	proxyListener := &proxyproto.Listener{Listener: web.TCPKeepAliveListener{TCPListener: ln.(*net.TCPListener)}, ConnPolicy: utils.GetProxyConnectionPolicy()}
+	proxyListener := &proxyproto.Listener{
+		Listener: web.TCPKeepAliveListener{
+			TCPListener: ln.(*net.TCPListener),
+		},
+		ConnPolicy: utils.GetProxyConnectionPolicy(),
+	}
 	defer func() {
 		err := proxyListener.Close()
 		if err != nil {

schema.yml

@@ -4460,6 +4460,15 @@ paths:
         name: branding_title
         schema:
           type: string
+      - in: query
+        name: client_certificates
+        schema:
+          type: array
+          items:
+            type: string
+            format: uuid
+        explode: true
+        style: form
       - in: query
         name: default
         schema:
@@ -24978,6 +24987,7 @@ paths:
           - authentik_stages_identification.identificationstage
           - authentik_stages_invitation.invitation
           - authentik_stages_invitation.invitationstage
+          - authentik_stages_mtls.mutualtlsstage
           - authentik_stages_password.passwordstage
           - authentik_stages_prompt.prompt
           - authentik_stages_prompt.promptstage
@@ -25226,6 +25236,7 @@ paths:
           - authentik_stages_identification.identificationstage
           - authentik_stages_invitation.invitation
           - authentik_stages_invitation.invitationstage
+          - authentik_stages_mtls.mutualtlsstage
           - authentik_stages_password.passwordstage
           - authentik_stages_prompt.prompt
           - authentik_stages_prompt.promptstage
@@ -37718,6 +37729,311 @@ paths:
               schema:
                 $ref: '#/components/schemas/GenericError'
           description: ''
+  /stages/mtls/:
+    get:
+      operationId: stages_mtls_list
+      description: MutualTLSStage Viewset
+      parameters:
+      - in: query
+        name: cert_attribute
+        schema:
+          type: string
+          enum:
+          - common_name
+          - email
+          - subject
+      - in: query
+        name: certificate_authorities
+        schema:
+          type: array
+          items:
+            type: string
+            format: uuid
+        explode: true
+        style: form
+      - in: query
+        name: mode
+        schema:
+          type: string
+          enum:
+          - optional
+          - required
+      - in: query
+        name: name
+        schema:
+          type: string
+      - name: ordering
+        required: false
+        in: query
+        description: Which field to use when ordering the results.
+        schema:
+          type: string
+      - name: page
+        required: false
+        in: query
+        description: A page number within the paginated result set.
+        schema:
+          type: integer
+      - name: page_size
+        required: false
+        in: query
+        description: Number of results to return per page.
+        schema:
+          type: integer
+      - name: search
+        required: false
+        in: query
+        description: A search term.
+        schema:
+          type: string
+      - in: query
+        name: stage_uuid
+        schema:
+          type: string
+          format: uuid
+      - in: query
+        name: user_attribute
+        schema:
+          type: string
+          enum:
+          - email
+          - username
+      tags:
+      - stages
+      security:
+      - authentik: []
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/PaginatedMutualTLSStageList'
+          description: ''
+        '400':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ValidationError'
+          description: ''
+        '403':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/GenericError'
+          description: ''
+    post:
+      operationId: stages_mtls_create
+      description: MutualTLSStage Viewset
+      tags:
+      - stages
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/MutualTLSStageRequest'
+        required: true
+      security:
+      - authentik: []
+      responses:
+        '201':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/MutualTLSStage'
+          description: ''
+        '400':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ValidationError'
+          description: ''
+        '403':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/GenericError'
+          description: ''
+  /stages/mtls/{stage_uuid}/:
+    get:
+      operationId: stages_mtls_retrieve
+      description: MutualTLSStage Viewset
+      parameters:
+      - in: path
+        name: stage_uuid
+        schema:
+          type: string
+          format: uuid
+        description: A UUID string identifying this Mutual TLS Stage.
+        required: true
+      tags:
+      - stages
+      security:
+      - authentik: []
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/MutualTLSStage'
+          description: ''
+        '400':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ValidationError'
+          description: ''
+        '403':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/GenericError'
+          description: ''
+    put:
+      operationId: stages_mtls_update
+      description: MutualTLSStage Viewset
+      parameters:
+      - in: path
+        name: stage_uuid
+        schema:
+          type: string
+          format: uuid
+        description: A UUID string identifying this Mutual TLS Stage.
+        required: true
+      tags:
+      - stages
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/MutualTLSStageRequest'
+        required: true
+      security:
+      - authentik: []
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/MutualTLSStage'
+          description: ''
+        '400':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ValidationError'
+          description: ''
+        '403':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/GenericError'
+          description: ''
+    patch:
+      operationId: stages_mtls_partial_update
+      description: MutualTLSStage Viewset
+      parameters:
+      - in: path
+        name: stage_uuid
+        schema:
+          type: string
+          format: uuid
+        description: A UUID string identifying this Mutual TLS Stage.
+        required: true
+      tags:
+      - stages
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/PatchedMutualTLSStageRequest'
+      security:
+      - authentik: []
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/MutualTLSStage'
+          description: ''
+        '400':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ValidationError'
+          description: ''
+        '403':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/GenericError'
+          description: ''
+    delete:
+      operationId: stages_mtls_destroy
+      description: MutualTLSStage Viewset
+      parameters:
+      - in: path
+        name: stage_uuid
+        schema:
+          type: string
+          format: uuid
+        description: A UUID string identifying this Mutual TLS Stage.
+        required: true
+      tags:
+      - stages
+      security:
+      - authentik: []
+      responses:
+        '204':
+          description: No response body
+        '400':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ValidationError'
+          description: ''
+        '403':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/GenericError'
+          description: ''
+  /stages/mtls/{stage_uuid}/used_by/:
+    get:
+      operationId: stages_mtls_used_by_list
+      description: Get a list of all objects that use this object
+      parameters:
+      - in: path
+        name: stage_uuid
+        schema:
+          type: string
+          format: uuid
+        description: A UUID string identifying this Mutual TLS Stage.
+        required: true
+      tags:
+      - stages
+      security:
+      - authentik: []
+      responses:
+        '200':
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/UsedBy'
+          description: ''
+        '400':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/ValidationError'
+          description: ''
+        '403':
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/GenericError'
+          description: ''
   /stages/password/:
     get:
       operationId: stages_password_list
@@ -40946,6 +41262,7 @@ components:
       - authentik.enterprise.providers.microsoft_entra
       - authentik.enterprise.providers.ssf
       - authentik.enterprise.stages.authenticator_endpoint_gdtc
+      - authentik.enterprise.stages.mtls
       - authentik.enterprise.stages.source
       - authentik.events
       type: string
@@ -42609,6 +42926,12 @@ components:
           format: uuid
           nullable: true
           description: Web Certificate used by the authentik Core webserver.
+        client_certificates:
+          type: array
+          items:
+            type: string
+            format: uuid
+          description: Certificates used for client authentication.
         attributes: {}
       required:
       - brand_uuid
@@ -42673,6 +42996,12 @@ components:
           format: uuid
           nullable: true
           description: Web Certificate used by the authentik Core webserver.
+        client_certificates:
+          type: array
+          items:
+            type: string
+            format: uuid
+          description: Certificates used for client authentication.
         attributes: {}
       required:
       - domain
@@ -42842,6 +43171,12 @@ components:
       - name
       - private_key
       - public_key
+    CertAttributeEnum:
+      enum:
+      - subject
+      - common_name
+      - email
+      type: string
     CertificateData:
       type: object
       description: Get CertificateKeyPair's data
@@ -48368,6 +48703,7 @@ components:
       - authentik_providers_microsoft_entra.microsoftentraprovidermapping
       - authentik_providers_ssf.ssfprovider
       - authentik_stages_authenticator_endpoint_gdtc.authenticatorendpointgdtcstage
+      - authentik_stages_mtls.mutualtlsstage
       - authentik_stages_source.sourcestage
       - authentik_events.event
       - authentik_events.notificationtransport
@@ -48375,6 +48711,96 @@ components:
       - authentik_events.notificationrule
       - authentik_events.notificationwebhookmapping
       type: string
+    MutualTLSStage:
+      type: object
+      description: MutualTLSStage Serializer
+      properties:
+        pk:
+          type: string
+          format: uuid
+          readOnly: true
+          title: Stage uuid
+        name:
+          type: string
+        component:
+          type: string
+          description: Get object type so that we know how to edit the object
+          readOnly: true
+        verbose_name:
+          type: string
+          description: Return object's verbose_name
+          readOnly: true
+        verbose_name_plural:
+          type: string
+          description: Return object's plural verbose_name
+          readOnly: true
+        meta_model_name:
+          type: string
+          description: Return internal model name
+          readOnly: true
+        flow_set:
+          type: array
+          items:
+            $ref: '#/components/schemas/FlowSet'
+        mode:
+          $ref: '#/components/schemas/MutualTLSStageModeEnum'
+        certificate_authorities:
+          type: array
+          items:
+            type: string
+            format: uuid
+          description: Configure certificate authorities to validate the certificate
+            against. This option has a higher priority than the `client_certificate`
+            option on `Brand`.
+        cert_attribute:
+          $ref: '#/components/schemas/CertAttributeEnum'
+        user_attribute:
+          $ref: '#/components/schemas/UserAttributeEnum'
+      required:
+      - cert_attribute
+      - component
+      - meta_model_name
+      - mode
+      - name
+      - pk
+      - user_attribute
+      - verbose_name
+      - verbose_name_plural
+    MutualTLSStageModeEnum:
+      enum:
+      - optional
+      - required
+      type: string
+    MutualTLSStageRequest:
+      type: object
+      description: MutualTLSStage Serializer
+      properties:
+        name:
+          type: string
+          minLength: 1
+        flow_set:
+          type: array
+          items:
+            $ref: '#/components/schemas/FlowSetRequest'
+        mode:
+          $ref: '#/components/schemas/MutualTLSStageModeEnum'
+        certificate_authorities:
+          type: array
+          items:
+            type: string
+            format: uuid
+          description: Configure certificate authorities to validate the certificate
+            against. This option has a higher priority than the `client_certificate`
+            option on `Brand`.
+        cert_attribute:
+          $ref: '#/components/schemas/CertAttributeEnum'
+        user_attribute:
+          $ref: '#/components/schemas/UserAttributeEnum'
+      required:
+      - cert_attribute
+      - mode
+      - name
+      - user_attribute
     NameIdPolicyEnum:
       enum:
       - urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress
@@ -50220,6 +50646,18 @@ components:
       required:
       - pagination
       - results
+    PaginatedMutualTLSStageList:
+      type: object
+      properties:
+        pagination:
+          $ref: '#/components/schemas/Pagination'
+        results:
+          type: array
+          items:
+            $ref: '#/components/schemas/MutualTLSStage'
+      required:
+      - pagination
+      - results
     PaginatedNotificationList:
       type: object
       properties:
@@ -51896,6 +52334,12 @@ components:
           format: uuid
           nullable: true
           description: Web Certificate used by the authentik Core webserver.
+        client_certificates:
+          type: array
+          items:
+            type: string
+            format: uuid
+          description: Certificates used for client authentication.
         attributes: {}
     PatchedCaptchaStageRequest:
       type: object
@@ -53079,6 +53523,31 @@ components:
           type: boolean
           description: When enabled, provider will not modify or create objects in
             the remote system.
+    PatchedMutualTLSStageRequest:
+      type: object
+      description: MutualTLSStage Serializer
+      properties:
+        name:
+          type: string
+          minLength: 1
+        flow_set:
+          type: array
+          items:
+            $ref: '#/components/schemas/FlowSetRequest'
+        mode:
+          $ref: '#/components/schemas/MutualTLSStageModeEnum'
+        certificate_authorities:
+          type: array
+          items:
+            type: string
+            format: uuid
+          description: Configure certificate authorities to validate the certificate
+            against. This option has a higher priority than the `client_certificate`
+            option on `Brand`.
+        cert_attribute:
+          $ref: '#/components/schemas/CertAttributeEnum'
+        user_attribute:
+          $ref: '#/components/schemas/UserAttributeEnum'
     PatchedNotificationRequest:
       type: object
       description: Notification Serializer
@@ -59793,6 +60262,11 @@ components:
       - pk
       - uid
       - username
+    UserAttributeEnum:
+      enum:
+      - username
+      - email
+      type: string
     UserConsent:
       type: object
       description: UserConsent Serializer

web/src/admin/brands/BrandForm.ts

@@ -1,9 +1,12 @@
+import { certificateProvider, certificateSelector } from "@goauthentik/admin/brands/Certificates";
 import "@goauthentik/admin/common/ak-crypto-certificate-search";
 import "@goauthentik/admin/common/ak-flow-search/ak-flow-search";
 import { DEFAULT_CONFIG } from "@goauthentik/common/api/config";
 import { DefaultBrand } from "@goauthentik/common/ui/config";
 import "@goauthentik/elements/CodeMirror";
 import { CodeMirrorMode } from "@goauthentik/elements/CodeMirror";
+import "@goauthentik/elements/ak-dual-select/ak-dual-select-dynamic-selected-provider.js";
+import "@goauthentik/elements/ak-dual-select/ak-dual-select-provider.js";
 import "@goauthentik/elements/forms/FormGroup";
 import "@goauthentik/elements/forms/HorizontalFormElement";
 import { ModelForm } from "@goauthentik/elements/forms/ModelForm";
@@ -303,6 +306,17 @@ export class BrandForm extends ModelForm<Brand, string> {
                             .certificate=${this.instance?.webCertificate}
                         ></ak-crypto-certificate-search>
                     </ak-form-element-horizontal>
+                    <ak-form-element-horizontal
+                        label=${msg("Client Certificates")}
+                        name="clientCertificates"
+                    >
+                        <ak-dual-select-dynamic-selected
+                            .provider=${certificateProvider}
+                            .selector=${certificateSelector(this.instance?.clientCertificates)}
+                            available-label=${msg("Available Certificates")}
+                            selected-label=${msg("Selected Certificates")}
+                        ></ak-dual-select-dynamic-selected>
+                    </ak-form-element-horizontal>
                     <ak-form-element-horizontal label=${msg("Attributes")} name="attributes">
                         <ak-codemirror
                             mode=${CodeMirrorMode.YAML}

web/src/admin/brands/Certificates.ts

@@ -0,0 +1,39 @@
+import { DEFAULT_CONFIG } from "@goauthentik/common/api/config";
+
+import { CertificateKeyPair, CryptoApi } from "@goauthentik/api";
+
+const certToSelect = (s: CertificateKeyPair) => [s.pk, s.name, s.name, s];
+
+export async function certificateProvider(page = 1, search = "") {
+    const certificates = await new CryptoApi(DEFAULT_CONFIG).cryptoCertificatekeypairsList({
+        ordering: "name",
+        pageSize: 20,
+        search: search.trim(),
+        page,
+        hasKey: undefined,
+    });
+    return {
+        pagination: certificates.pagination,
+        options: certificates.results.map(certToSelect),
+    };
+}
+
+export function certificateSelector(instanceMappings?: string[]) {
+    if (!instanceMappings) {
+        return [];
+    }
+
+    return async () => {
+        const pm = new CryptoApi(DEFAULT_CONFIG);
+        const mappings = await Promise.allSettled(
+            instanceMappings.map((instanceId) =>
+                pm.cryptoCertificatekeypairsRetrieve({ kpUuid: instanceId }),
+            ),
+        );
+
+        return mappings
+            .filter((s) => s.status === "fulfilled")
+            .map((s) => s.value)
+            .map(certToSelect);
+    };
+}

web/src/admin/stages/StageListPage.ts

@@ -16,6 +16,7 @@ import "@goauthentik/admin/stages/dummy/DummyStageForm";
 import "@goauthentik/admin/stages/email/EmailStageForm";
 import "@goauthentik/admin/stages/identification/IdentificationStageForm";
 import "@goauthentik/admin/stages/invitation/InvitationStageForm";
+import "@goauthentik/admin/stages/mtls/MTLSStageForm";
 import "@goauthentik/admin/stages/password/PasswordStageForm";
 import "@goauthentik/admin/stages/prompt/PromptStageForm";
 import "@goauthentik/admin/stages/redirect/RedirectStageForm";

web/src/admin/stages/StageWizard.ts

@@ -14,6 +14,7 @@ import "@goauthentik/admin/stages/dummy/DummyStageForm";
 import "@goauthentik/admin/stages/email/EmailStageForm";
 import "@goauthentik/admin/stages/identification/IdentificationStageForm";
 import "@goauthentik/admin/stages/invitation/InvitationStageForm";
+import "@goauthentik/admin/stages/mtls/MTLSStageForm";
 import "@goauthentik/admin/stages/password/PasswordStageForm";
 import "@goauthentik/admin/stages/prompt/PromptStageForm";
 import "@goauthentik/admin/stages/redirect/RedirectStageForm";

web/src/admin/stages/mtls/MTLSStageForm.ts

@@ -0,0 +1,162 @@
+import { certificateProvider, certificateSelector } from "@goauthentik/admin/brands/Certificates";
+import "@goauthentik/admin/common/ak-crypto-certificate-search";
+import { BaseStageForm } from "@goauthentik/admin/stages/BaseStageForm";
+import { DEFAULT_CONFIG } from "@goauthentik/common/api/config";
+import "@goauthentik/elements/ak-dual-select/ak-dual-select-dynamic-selected-provider.js";
+import "@goauthentik/elements/ak-dual-select/ak-dual-select-provider.js";
+import "@goauthentik/elements/forms/FormGroup";
+import "@goauthentik/elements/forms/HorizontalFormElement";
+import "@goauthentik/elements/forms/Radio";
+
+import { msg } from "@lit/localize";
+import { TemplateResult, html } from "lit";
+import { customElement } from "lit/decorators.js";
+import { ifDefined } from "lit/directives/if-defined.js";
+
+import {
+    CertAttributeEnum,
+    MutualTLSStage,
+    MutualTLSStageModeEnum,
+    StagesApi,
+    UserAttributeEnum,
+} from "@goauthentik/api";
+
+@customElement("ak-stage-mtls-form")
+export class MTLSStageForm extends BaseStageForm<MutualTLSStage> {
+    loadInstance(pk: string): Promise<MutualTLSStage> {
+        return new StagesApi(DEFAULT_CONFIG).stagesMtlsRetrieve({
+            stageUuid: pk,
+        });
+    }
+
+    async send(data: MutualTLSStage): Promise<MutualTLSStage> {
+        if (this.instance) {
+            return new StagesApi(DEFAULT_CONFIG).stagesMtlsUpdate({
+                stageUuid: this.instance.pk || "",
+                mutualTLSStageRequest: data,
+            });
+        } else {
+            return new StagesApi(DEFAULT_CONFIG).stagesMtlsCreate({
+                mutualTLSStageRequest: data,
+            });
+        }
+    }
+
+    renderForm(): TemplateResult {
+        return html`
+            <span> ${msg("Client-certificate/mTLS authentication/enrollment.")} </span>
+            <ak-form-element-horizontal label=${msg("Name")} ?required=${true} name="name">
+                <input
+                    type="text"
+                    value="${ifDefined(this.instance?.name || "")}"
+                    class="pf-c-form-control"
+                    required
+                />
+            </ak-form-element-horizontal>
+            <ak-form-group .expanded=${true}>
+                <span slot="header"> ${msg("Stage-specific settings")} </span>
+                <div slot="body" class="pf-c-form">
+                    <ak-form-element-horizontal label=${msg("Mode")} required name="mode">
+                        <ak-radio
+                            .options=${[
+                                {
+                                    label: msg("Certificate optional"),
+                                    value: MutualTLSStageModeEnum.Optional,
+                                    default: true,
+                                    description: html`${msg(
+                                        "If no certificate was provided, this stage will succeed and continue to the next stage.",
+                                    )}`,
+                                },
+                                {
+                                    label: msg("Certificate required"),
+                                    value: MutualTLSStageModeEnum.Required,
+                                    description: html`${msg(
+                                        "If no certificate was provided, this stage will stop flow execution.",
+                                    )}`,
+                                },
+                            ]}
+                            .value=${this.instance?.mode}
+                        >
+                        </ak-radio>
+                    </ak-form-element-horizontal>
+                    <ak-form-element-horizontal
+                        label=${msg("Certificate authorities")}
+                        name="certificateAuthorities"
+                    >
+                        <ak-dual-select-dynamic-selected
+                            .provider=${certificateProvider}
+                            .selector=${certificateSelector(this.instance?.certificateAuthorities)}
+                            available-label=${msg("Available Certificates")}
+                            selected-label=${msg("Selected Certificates")}
+                        ></ak-dual-select-dynamic-selected>
+                        <p class="pf-c-form__helper-text">
+                            ${msg(
+                                "Configure the certificate authority client certificates are validated against. The certificate authority can also be configured on a brand, which allows for different certificate authorities for different domains.",
+                            )}
+                        </p>
+                    </ak-form-element-horizontal>
+                    <ak-form-element-horizontal
+                        label=${msg("Certificate attribute")}
+                        required
+                        name="certAttribute"
+                    >
+                        <ak-radio
+                            .options=${[
+                                {
+                                    label: msg("Common Name"),
+                                    value: CertAttributeEnum.CommonName,
+                                },
+                                {
+                                    label: msg("Email"),
+                                    value: CertAttributeEnum.Email,
+                                    default: true,
+                                },
+                                {
+                                    label: msg("Subject"),
+                                    value: CertAttributeEnum.Subject,
+                                },
+                            ]}
+                            .value=${this.instance?.certAttribute}
+                        >
+                        </ak-radio>
+                        <p class="pf-c-form__helper-text">
+                            ${msg(
+                                "Configure the attribute of the certificate used to look for a user.",
+                            )}
+                        </p>
+                    </ak-form-element-horizontal>
+                    <ak-form-element-horizontal
+                        label=${msg("User attribute")}
+                        required
+                        name="userAttribute"
+                    >
+                        <ak-radio
+                            .options=${[
+                                {
+                                    label: msg("Username"),
+                                    value: UserAttributeEnum.Username,
+                                },
+                                {
+                                    label: msg("Email"),
+                                    value: UserAttributeEnum.Email,
+                                    default: true,
+                                },
+                            ]}
+                            .value=${this.instance?.userAttribute}
+                        >
+                        </ak-radio>
+                        <p class="pf-c-form__helper-text">
+                            ${msg("Configure the attribute of the user used to look for a user.")}
+                        </p>
+                    </ak-form-element-horizontal>
+                </div>
+            </ak-form-group>
+        `;
+    }
+}
+
+declare global {
+    interface HTMLElementTagNameMap {
+        "ak-stage-mtls-form": MTLSStageForm;
+    }
+}