[PATCH] ldap-auth

14 files changed, 301 insertions, 17 deletions

diff --git a/README.md b/README.md
index d3883ef4..2813f69d 100644
--- a/README.md
+++ b/README.md
@@ -35,6 +35,7 @@ https://www.newspipe.org
 * detection of inactive feeds;
 * share articles on Pinboard, Reddit and Twitter;
 * management of bookmarks (with import from Pinboard).
+* Optional ldap authentication
 
 
 ## Deployment
diff --git a/instance/config.py b/instance/config.py
index eae58a53..e3362694 100644
--- a/instance/config.py
+++ b/instance/config.py
@@ -71,3 +71,21 @@ ADMIN_EMAIL = "admin@admin.localhost"
 LOG_LEVEL = "info"
 LOG_PATH = "./var/newspipe.log"
 SELF_REGISTRATION = True
+
+# Ldap, optional
+LDAP_ENABLED = False
+# LDAP_URI will automatically try the _ldap._tcp lookups like for a kerberos domain but
+# will fall back to this exact domain (server) name if such a TXT record is not found.
+LDAP_URI = "ldaps://ipa.internal.com:636"
+LDAP_USER_BASE = "cn=users,cn=accounts,dc=ipa,dc=internal,dc=com"
+LDAP_GROUP_BASE = "cn=groups,cn=accounts,dc=ipa,dc=internal,dc=com"
+LDAP_USER_MATCH_ATTRIB = "uid"
+LDAP_USER_DISPLAY_ATTRIB = "uid"
+LDAP_USER_ATTRIB_MEMBEROF = "memberof"
+LDAP_GROUP_DISPLAY_ATTRIB = "cn"
+LDAP_BIND_DN = "uid=sampleuser,cn=users,cn=accounts,dc=ipa,dc=internal,dc=com"
+LDAP_BIND_PASSWORD = "examplepassword"
+# Additional filter to restrict user lookup. If not equivalent to False (e.g., undefined), will be logical-anded to the user-match-attribute search filter.
+LDAP_FILTER = (
+    "(memberOf=cn=newspipe-users,cn=groups,cn=accounts,dc=ipa,dc=internal,dc=com)"
+)
diff --git a/instance/sqlite.py b/instance/sqlite.py
index 9d171b89..de6aab23 100644
--- a/instance/sqlite.py
+++ b/instance/sqlite.py
@@ -64,3 +64,21 @@ LOG_LEVEL = "info"
 LOG_PATH = "./var/newspipe.log"
 SELF_REGISTRATION = True
 SQLALCHEMY_TRACK_MODIFICATIONS = False
+
+# Ldap, optional
+LDAP_ENABLED = False
+# LDAP_URI will automatically try the _ldap._tcp lookups like for a kerberos domain but
+# will fall back to this exact domain (server) name if such a TXT record is not found.
+LDAP_URI = "ldaps://ipa.internal.com:636"
+LDAP_USER_BASE = "cn=users,cn=accounts,dc=ipa,dc=internal,dc=com"
+LDAP_GROUP_BASE = "cn=groups,cn=accounts,dc=ipa,dc=internal,dc=com"
+LDAP_USER_MATCH_ATTRIB = "uid"
+LDAP_USER_DISPLAY_ATTRIB = "uid"
+LDAP_USER_ATTRIB_MEMBEROF = "memberof"
+LDAP_GROUP_DISPLAY_ATTRIB = "cn"
+LDAP_BIND_DN = "uid=sampleuser,cn=users,cn=accounts,dc=ipa,dc=internal,dc=com"
+LDAP_BIND_PASSWORD = "examplepassword"
+# Additional filter to restrict user lookup. If not equivalent to False (e.g., undefined), will be logical-anded to the user-match-attribute search filter.
+LDAP_FILTER = (
+    "(memberOf=cn=newspipe-users,cn=groups,cn=accounts,dc=ipa,dc=internal,dc=com)"
+)
diff --git a/migrations/versions/2a5604bed382_add_string_user_external_auth.py b/migrations/versions/2a5604bed382_add_string_user_external_auth.py
new file mode 100644
index 00000000..95fe3ac9
--- /dev/null
+++ b/migrations/versions/2a5604bed382_add_string_user_external_auth.py
@@ -0,0 +1,23 @@
+"""add_string_user_external_auth
+
+Revision ID: 2a5604bed382
+Revises: bdd38bd755cb
+Create Date: 2023-06-17 15:30:40.434393
+
+"""
+# revision identifiers, used by Alembic.
+revision = "2a5604bed382"
+down_revision = "bdd38bd755cb"
+branch_labels = None
+depends_on = None
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.add_column("user", sa.Column("external_auth", sa.String(), nullable=True))
+
+
+def downgrade():
+    op.drop_column("user", "external_auth")
diff --git a/newspipe/controllers/__init__.py b/newspipe/controllers/__init__.py
index 6769aa32..449d93e9 100644
--- a/newspipe/controllers/__init__.py
+++ b/newspipe/controllers/__init__.py
@@ -1,7 +1,7 @@
 from .feed import FeedController
 from .category import CategoryController  # noreorder
 from .article import ArticleController
-from .user import UserController
+from .user import UserController, LdapuserController
 from .icon import IconController
 from .bookmark import BookmarkController
 from .tag import BookmarkTagController
diff --git a/newspipe/controllers/user.py b/newspipe/controllers/user.py
index 64dac06c..e259940e 100644
--- a/newspipe/controllers/user.py
+++ b/newspipe/controllers/user.py
@@ -1,4 +1,5 @@
 import logging
+from urllib.parse import urlparse
 
 from werkzeug.security import check_password_hash
 from werkzeug.security import generate_password_hash
@@ -8,6 +9,11 @@ from newspipe.models import User
 
 logger = logging.getLogger(__name__)
 
+# FOR LDAP
+# Reference: session_app
+import ldap3
+from ldap3.core.exceptions import LDAPBindError, LDAPPasswordIsMandatoryError
+
 
 class UserController(AbstractController):
     _db_cls = User
@@ -29,3 +35,140 @@ class UserController(AbstractController):
     def update(self, filters, attrs):
         self._handle_password(attrs)
         return super().update(filters, attrs)
+
+
+class LdapuserController:
+    def check_password(self, user, password, config):
+        this_uri = self.get_next_ldap_server(config)
+        # return this_uri
+        this_user = self.list_matching_users(
+            server_uri=this_uri,
+            bind_dn=config["LDAP_BIND_DN"],
+            bind_pw=config["LDAP_BIND_PASSWORD"],
+            user_base=config["LDAP_USER_BASE"],
+            username=user,
+            user_match_attrib=config["LDAP_USER_MATCH_ATTRIB"],
+            _filter=config["LDAP_FILTER"] if "LDAP_FILTER" in config else "",
+        )
+        # list_matching_users always returns list, so if it contains <> 1 we are in trouble
+        if len(this_user) != 1:
+            print(
+                f"WARNING: cannot determine unique user for {config['LDAP_USER_MATCH_ATTRIB']}={user} which returned {this_user}"
+            )
+            return False
+        # logger does not work here+flask for some reason. Very sad!
+        # now we have exactly one user, this_user[0]
+        this_user = this_user[0]
+
+        ldapuser = self.authenticated_user(
+            server_uri=this_uri, user_dn=this_user, password=password
+        )
+        if ldapuser:
+            return ldapuser
+        # return str(config)
+        # return this_user
+        return False
+
+    def get_next_ldap_server(self, config):
+        # on first ldap_login attempt, cache this lookup result:
+        if "LDAP_HOSTS" not in config:
+            this_domain = urlparse(config["LDAP_URI"]).hostname
+            config["LDAP_HOSTS"] = self.list_ldap_servers_for_domain(this_domain)
+        else:
+            # rotate them! So every ldap_login attempt will use the next ldap server in the list.
+            this_list = config["LDAP_HOSTS"]
+            a = this_list[0]
+            this_list.append(a)
+            this_list.pop(0)
+            config["LDAP_HOSTS"] = this_list
+        # construct a new, full uri.
+        this_netloc = config["LDAP_HOSTS"][0]
+        up = urlparse(config["LDAP_URI"])
+        if up.port:
+            this_netloc += f":{up.port}"
+        this_uri = up._replace(netloc=this_netloc).geturl()
+        return this_uri
+
+    def list_matching_users(
+        self,
+        server_uri="",
+        bind_dn="",
+        bind_pw="",
+        connection=None,
+        user_base="",
+        username="",
+        user_match_attrib="",
+        _filter="",
+    ):
+        search_filter = f"({user_match_attrib}={username})"
+        if _filter:
+            search_filter = f"(&{search_filter}{_filter})"
+        if connection and isinstance(connection, ldap3.core.connection.Connection):
+            conn = connection
+        else:
+            conn = self.get_ldap_connection(server_uri, bind_dn, bind_pw)
+        conn.search(
+            search_base=user_base, search_filter=search_filter, search_scope="SUBTREE"
+        )
+        print(f"DEBUG: search_base {user_base}")
+        print(f"DEBUG: search_filter {search_filter}")
+        result = []
+        for i in conn.entries:
+            result.append(i.entry_dn)
+        print(f"DEBUG: result {result}")
+        return result
+
+    def get_ldap_connection(self, server_uri, bind_dn, bind_pw):
+        server = ldap3.Server(server_uri)
+        conn = ldap3.Connection(server, auto_bind=True, user=bind_dn, password=bind_pw)
+        return conn
+
+    def list_ldap_servers_for_domain(self, domain):
+        # return list of hostnames from the _ldap._tcp.{domain} SRV lookup
+        try:
+            import dns
+            import dns.resolver
+        except:
+            print("Need python3-dns or dnspython installed for dns lookups.")
+            return [domain]
+        namelist = []
+        try:
+            query = dns.resolver.query(f"_ldap._tcp.{domain}", "SRV")
+        except dns.resolver.NXDOMAIN:
+            # no records exist that match the request, so we were probably given a specific hostname, and an empty query will trigger the logic below that will add the original domain to the list.
+            query = []
+        for i in query:
+            namelist.append(i.target.to_text().rstrip("."))
+        if not len(namelist):
+            namelist.append(domain)
+        return namelist
+
+    def ldap_login(self, username, password):
+        # print(f"DEBUG: Trying user {username} with pw '{password}'")
+        this_uri = self.get_next_ldap_server(app)
+        # Perform the ldap interactions
+        user = self.authenticated_user(
+            server_uri=this_uri, user_dn=username, password=password
+        )
+        if user:
+            return user
+        else:
+            return False
+        return False
+
+    def authenticated_user(self, server_uri, user_dn, password):
+        print(f"server_uri: {server_uri}")
+        print(f"user_dn: {user_dn}")
+        try:
+            conn = self.get_ldap_connection(server_uri, user_dn, password)
+            return conn
+        except LDAPBindError as e:
+            if "invalidCredentials" in str(e):
+                print("Invalid credentials.")
+                return False
+            else:
+                raise e
+        # except (LDAPPasswordIsMandatoryError, LDAPBindError):
+        #   print("Either an ldap password is required, or we had another bind error.")
+        #   return False
+        return False
diff --git a/newspipe/models/user.py b/newspipe/models/user.py
index b095fdf1..72c35afc 100644
--- a/newspipe/models/user.py
+++ b/newspipe/models/user.py
@@ -46,6 +46,7 @@ class User(db.Model, UserMixin, RightMixin):
     id = db.Column(db.Integer, primary_key=True)
     nickname = db.Column(db.String(), unique=True)
     pwdhash = db.Column(db.String())
+    external_auth = db.Column(db.String(), default="", nullable=True)
 
     automatic_crawling = db.Column(db.Boolean(), default=True)
 
diff --git a/newspipe/templates/admin/create_user.html b/newspipe/templates/admin/create_user.html
index 2cfe4518..550cfd1f 100644
--- a/newspipe/templates/admin/create_user.html
+++ b/newspipe/templates/admin/create_user.html
@@ -9,7 +9,7 @@
       {{ form.nickname(class_="form-control") }} {% for error in form.nickname.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
 
       {{ form.password.label }}
-      {{ form.password(class_="form-control") }} {% for error in form.password.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
+      {% if pw_disabled %}{{ form.password(class_="form-control",disabled=True) }}{% else %}{{ form.password(class_="form-control") }}{% endif %} {% for error in form.password.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
 
       {{ form.automatic_crawling.label }}
       {{ form.automatic_crawling(class_="form-check-input") }} {% for error in form.automatic_crawling.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
diff --git a/newspipe/templates/admin/dashboard.html b/newspipe/templates/admin/dashboard.html
index db56be25..370ab702 100644
--- a/newspipe/templates/admin/dashboard.html
+++ b/newspipe/templates/admin/dashboard.html
@@ -9,6 +9,7 @@
             <th>{{ _('Nickname') }}</th>
             <th>{{ _('Member since') }}</th>
             <th>{{ _('Last seen') }}</th>
+            <th>{{ _('External auth') }}</th>
             <th>{{ _('Actions') }}</th>
         </tr>
     </thead>
@@ -26,6 +27,7 @@
             </td>
             <td class="date">{{ user.date_created | datetime }}</td>
             <td class="date">{{ user.last_seen | datetime }}</td>
+            <td class="date">{{ user.external_auth | safe }}</td>
             <td>
                 <a href="{{ url_for("admin.user_form", user_id=user.id) }}"><i class="fa fa-pencil-square-o" aria-hidden="true" title="{{ _('Edit this user') }}"></i></a>
                 {% if user.id != current_user.id %}
diff --git a/newspipe/templates/profile.html b/newspipe/templates/profile.html
index 6cb59ed5..12e0682a 100644
--- a/newspipe/templates/profile.html
+++ b/newspipe/templates/profile.html
@@ -21,13 +21,13 @@
 
                     <div class="col">
                         {{ form.nickname.label }}
-                        {{ form.nickname(class_="form-control") }} {% for error in form.nickname.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
+                        {% if nick_disabled %}{{ form.nickname(class_="form-control", disabled=True) }}{% else %}{{ form.nickname(class_="form-control") }}{% endif %} {% for error in form.nickname.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
 
-                        {{ form.password.label }}
+                        {% if not user.external_auth %}{{ form.password.label }}
                         {{ form.password(class_="form-control") }} {% for error in form.password.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
 
                         {{ form.password_conf.label }}
-                        {{ form.password_conf(class_="form-control") }} {% for error in form.password_conf.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}
+                        {{ form.password_conf(class_="form-control") }} {% for error in form.password_conf.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}{% else%}{% for error in form.password.errors %} <span style="color: red;">{{ error }}<br /></span>{% endfor %}No password management for auth type {{  user.external_auth }}{% endif %}
                     </div>
 
                     <div class="col">
diff --git a/newspipe/web/forms.py b/newspipe/web/forms.py
index 1240e4ab..dba2e1b8 100644
--- a/newspipe/web/forms.py
+++ b/newspipe/web/forms.py
@@ -1,4 +1,5 @@
 #! /usr/bin/env python
+# vim: set ts=4 sts=4 sw=4 et:
 # Newspipe - A web news aggregator.
 # Copyright (C) 2010-2023 Cédric Bonhomme - https://www.cedricbonhomme.org
 #
@@ -24,6 +25,7 @@ __revision__ = "$Date: 2015/05/06 $"
 __copyright__ = "Copyright (c) Cedric Bonhomme"
 __license__ = "GPLv3"
 
+import logging
 from flask import redirect, url_for
 from flask_babel import lazy_gettext
 from flask_wtf import FlaskForm
@@ -41,10 +43,13 @@ from wtforms import (
 )
 from wtforms.fields.html5 import EmailField, URLField
 
-from newspipe.controllers import UserController
+from newspipe.bootstrap import application
+from newspipe.controllers import UserController, LdapuserController
 from newspipe.lib import misc_utils
 from newspipe.models import User
 
+logger = logging.getLogger(__name__)
+
 
 class SignupForm(FlaskForm):
     """
@@ -138,19 +143,76 @@ class SigninForm(RedirectForm):
 
     def validate(self):
         validated = super().validate()
+        # try ldap before doing anything else
+        ldap_enabled = (
+            application.config["LDAP_ENABLED"]
+            if "LDAP_ENABLED" in application.config
+            else False
+        )
+        ldapuser = None
+        if ldap_enabled:
+            ucontrldap = LdapuserController()
+            try:
+                # this returns False if invalid username or password.
+                ldapuser = ucontrldap.check_password(
+                    user=self.nickmane.data,
+                    password=self.password.data,
+                    config=application.config,
+                )
+                if ldapuser:
+                    self.nickmane.errors.append(
+                        f"validated ldap user {self.nickmane.data}"
+                    )
+                else:
+                    # self.nickmane.errors.append(f"Invalid username or password.")
+                    raise NotFound
+            except NotFound:
+                pass  # just assume the user is trying a local account
         ucontr = UserController()
         try:
             user = ucontr.get(nickname=self.nickmane.data)
         except NotFound:
-            self.nickmane.errors.append("Wrong nickname")
-            validated = False
+            if ldap_enabled and ldapuser:
+                try:
+                    user = ucontr.create(
+                        nickname=self.nickmane.data,
+                        password="",
+                        automatic_crawling=True,
+                        is_admin=False,
+                        is_active=True,
+                        external_auth="ldap",
+                    )
+                    if user:
+                        validated = True
+                        self.user = user
+                except:
+                    self.nickmane.errors.append(
+                        f"Unable to provision user for valid ldap user {self.nickmane.data}"
+                    )
+                    validated = False
+            else:
+                self.nickmane.errors.append("Wrong nickname")
+                validated = False
         else:
             if not user.is_active:
                 self.nickmane.errors.append("Account not active")
                 validated = False
-            if not ucontr.check_password(user, self.password.data):
-                self.password.errors.append("Wrong password")
-                validated = False
+            # must short-circuit the password check for ldap users
+            if not ldapuser:
+                try:
+                    # with an external_auth user but external auth disabled in config now, the empty password on the user in the database will fail
+                    if not ucontr.check_password(user, self.password.data):
+                        self.password.errors.append("Wrong password")
+                        validated = False
+                except AttributeError:
+                    if ldap_enabled:
+                        self.password.errors.append("Wrong password")
+                        validated = False
+                    else:
+                        self.password.errors.append(
+                            "External auth {user.external_auth} unavailable. Contact the admin."
+                        )
+                        validated = False
             self.user = user
         return validated
 
@@ -188,7 +250,8 @@ class ProfileForm(FlaskForm):
 
     nickname = TextField(
         lazy_gettext("Nickname"),
-        [validators.Required(lazy_gettext("Please enter your nickname."))],
+        # [validators.Required(lazy_gettext("Please enter your nickname."))],
+        [validators.Optional()],
     )
     password = PasswordField(lazy_gettext("Password"))
     password_conf = PasswordField(lazy_gettext("Password"))
@@ -213,7 +276,9 @@ class ProfileForm(FlaskForm):
                 )
                 self.password.errors.append(message)
                 validated = False
-        if self.nickname.data != User.make_valid_nickname(self.nickname.data):
+        if self.nickname.data and (
+            self.nickname.data != User.make_valid_nickname(self.nickname.data)
+        ):
             self.nickname.errors.append(
                 lazy_gettext(
                     "This nickname has "
diff --git a/newspipe/web/views/admin.py b/newspipe/web/views/admin.py
index b35a3f96..41169754 100644
--- a/newspipe/web/views/admin.py
+++ b/newspipe/web/views/admin.py
@@ -46,10 +46,17 @@ def user_form(user_id=None):
         user = UserController().get(id=user_id)
         form = UserForm(obj=user)
         message = gettext("Edit the user <i>%(nick)s</i>", nick=user.nickname)
+        if user.external_auth:
+            message += f" (external auth type: {user.external_auth})"
     else:
         form = UserForm()
         message = gettext("Add a new user")
-    return render_template("/admin/create_user.html", form=form, message=message)
+    return render_template(
+        "/admin/create_user.html",
+        form=form,
+        message=message,
+        pw_disabled=bool(user.external_auth),
+    )
 
 
 @admin_bp.route("/user/create", methods=["POST"])
diff --git a/newspipe/web/views/user.py b/newspipe/web/views/user.py
index b8d01967..1945be89 100644
--- a/newspipe/web/views/user.py
+++ b/newspipe/web/views/user.py
@@ -9,6 +9,7 @@ from flask_login import current_user
 from flask_login import login_required
 from flask_paginate import get_page_args
 from flask_paginate import Pagination
+from werkzeug.exceptions import BadRequest
 
 from newspipe.bootstrap import application
 from newspipe.controllers import ArticleController
@@ -165,6 +166,9 @@ def profile():
     if request.method == "POST":
         if form.validate():
             try:
+                # for external user, just force the exact same username.
+                if user.external_auth or not form.nickname.data:
+                    form.nickname.data = user.nickname
                 user_contr.update(
                     {"id": current_user.id},
                     {
@@ -195,7 +199,9 @@ def profile():
 
     if request.method == "GET":
         form = ProfileForm(obj=user)
-        return render_template("profile.html", user=user, form=form)
+        return render_template(
+            "profile.html", user=user, form=form, nick_disabled=bool(user.external_auth)
+        )
 
 
 @user_bp.route("/delete_account", methods=["GET"])
diff --git a/newspipe/web/views/views.py b/newspipe/web/views/views.py
index 7ff2a2e4..bb7bff2f 100644
--- a/newspipe/web/views/views.py
+++ b/newspipe/web/views/views.py
@@ -25,7 +25,7 @@ logger = logging.getLogger(__name__)
 
 @current_app.errorhandler(401)
 def authentication_required(error):
-    if application.conf["API_ROOT"] in request.url:
+    if application.config["API_ROOT"] in request.url:
         return error
     flash(gettext("Authentication required."), "info")
     return redirect(url_for("login"))
@@ -33,7 +33,7 @@ def authentication_required(error):
 
 @current_app.errorhandler(403)
 def authentication_failed(error):
-    if application.conf["API_ROOT"] in request.url:
+    if application.config["API_ROOT"] in request.url:
         return error
     flash(gettext("Forbidden."), "danger")
     return redirect(url_for("login"))