finish

README.md

@@ -0,0 +1,106 @@
+# Keycloak allow/ban plugin
+
+This is a plugin for Keycloak that checks an allow-list and a ban list for
+users from GitHub.
+
+## Configuration
+
+Add the plugin to your keycloak plugins list. The plugin can be obtained via
+`nix build .#packages.default`.
+
+The configuration of this plugin is in a directory of text files with the
+format `github-id github-username`, allowing `#` comments.
+
+Specify a Keycloak config file option
+`spi-authenticator-allow-ban-check-authenticator-dbpath` pointing to the
+directory with the configuration. Note that the error if you don't configure
+this is complete garbage, and is also not printed by default (sorry)! Use
+`kc.sh --verbose start` to read your `NullPointerException`.
+
+There are three notable files in there:
+- `banned-users.txt`: contains a list of GitHub IDs which will be rejected
+  outright on login.
+
+  If you newly ban a user, you have to kill all their sessions across all
+  infrastructure, including existing Keycloak sessions, since bans only apply
+  on login.
+- `allowed-users.txt`: contains a list of GitHub IDs which will be allowed if the
+  allow-list is enabled.
+- `use-allow-list.txt`: if present, the allow-list mechanism is used. Otherwise
+  it is bypassed and all logins are allowed.
+
+The intent of the configuration is that it is synced by a cron job pulling a
+git repo.
+
+## Setup
+
+1. In the GitHub Identity Provider configuration on Keycloak, set up a mapper with
+   type "Attribute Importer", importing the JSON field path "id" as a user
+   profile attribute "githubId".
+
+2. Create an auth flow for post login on the identity provider, containing one
+   element "Allow/Ban check". This is necessary since it bypasses the standard
+   login flow if you log in via the external IdP.
+
+3. In the identity provider, set the *Post Login Flow* to the flow just
+   created.
+
+4. Add the "Allow/Ban check" action to the main login flow as a Required
+   element at a point *after* the username is determined.
+
+## Notes
+
+We are unsure if Store Tokens is necessary to set; it is not for this plugin,
+but it might be a good idea to simply have them around.
+
+We don't think there are ways to ban-evade, since this is managed by a
+user-invisible profile attribute that is permanently glued to all accounts
+originating from GitHub.
+
+We have tested this on Keycloak 23 and 24.
+
+### Test environment!
+
+There is a test environment included with this plugin to avoid testing in prod.
+Run:
+
+```
+nix run .#
+```
+
+Then in a separate terminal:
+
+```
+sudo socat TCP-LISTEN:443,fork,reuseaddr TCP:127.0.0.1:4043
+```
+
+and add `127.0.0.1 identity.test.lix.systems` to `/etc/hosts`. Dump Firefox
+DNS cache if necessary (`about:networking`), and create a GitHub OAuth app.
+
+You can ssh into the machine on port 2022 on localhost as root, with no
+password.
+
+Then finally go to `https://identity.test.lix.systems/superadmin`, and log in
+with `admin`/`Password1`.
+
+### Attaching a debugger to Keycloak
+
+We are so sorry.
+
+If you are doing this to the VM here, change the last line of the keycloak
+startup script to this:
+
+`DEBUG=true DEBUG_PORT='*:1337' DEBUG_SUSPEND=y kc.sh --verbose start --optimized --debug`
+
+To actually make that work, you want to copy the file from `systemctl cat
+keycloak.service` to `/start-keycloak`, then `systemctl edit --runtime
+keycloak`, with the contents:
+
+```
+[Service]
+ExecStart=
+ExecStart=/start-keycloak
+```
+
+Then `systemctl restart keycloak`. Next create a forward like `ssh
+-L1337:localhost:1337 localvm` and attach your Java debugger to port 1337.

flake.lock

@@ -15,13 +15,37 @@
         "type": "github"
       }
     },
+    "microvm": {
+      "inputs": {
+        "flake-utils": [
+          "flake-utils"
+        ],
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "spectrum": "spectrum"
+      },
+      "locked": {
+        "lastModified": 1711159783,
+        "narHash": "sha256-nwl2Cygq7NrV9QcebJE/T/vXv7w+zLERD7ygHz0F5g8=",
+        "owner": "astro",
+        "repo": "microvm.nix",
+        "rev": "d31f7c7d3194c51372134832a3a2a256773c161a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "astro",
+        "repo": "microvm.nix",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1700612854,
+        "lastModified": 1711163522,
-        "narHash": "sha256-yrQ8osMD+vDLGFX7pcwsY/Qr5PUd6OmDMYJZzZi0+zc=",
+        "narHash": "sha256-YN/Ciidm+A0fmJPWlHBGvVkcarYWSC+s3NTPk/P+q3c=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "19cbff58383a4ae384dea4d1d0c823d72b49d614",
+        "rev": "44d0940ea560dee511026a53f0e2e2cde489b4d4",
         "type": "github"
       },
       "original": {
@@ -34,8 +58,25 @@
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
+        "microvm": "microvm",
         "nixpkgs": "nixpkgs"
       }
+    },
+    "spectrum": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1708358594,
+        "narHash": "sha256-e71YOotu2FYA67HoC/voJDTFsiPpZNRwmiQb4f94OxQ=",
+        "ref": "refs/heads/main",
+        "rev": "6d0e73864d28794cdbd26ab7b37259ab0e1e044c",
+        "revCount": 614,
+        "type": "git",
+        "url": "https://spectrum-os.org/git/spectrum"
+      },
+      "original": {
+        "type": "git",
+        "url": "https://spectrum-os.org/git/spectrum"
+      }
     }
   },
   "root": "root",

flake.nix

@@ -2,9 +2,14 @@
   inputs = {
     nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
     flake-utils.url = "github:numtide/flake-utils";
+    microvm = {
+      url = "github:astro/microvm.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+      inputs.flake-utils.follows = "flake-utils";
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils }:
+  outputs = { self, nixpkgs, flake-utils, microvm }:
     let
       out = system:
         let
@@ -14,41 +19,32 @@
           };
         in
         {
-          devShells.default = (pkgs.buildFHSEnv {
+          devShells.default = pkgs.mkShell {
-            name = "s4d-env";
+            buildInputs = with pkgs; [
-            targetPkgs = pkgs: (with pkgs; [
               jdk
               zlib
-              freetype
-              fontconfig
               maven
-              protobuf
+              nixos-rebuild
-            ]);
+            ];
-            runScript = "zsh";
-          }).env;
-
-          packages.default = pkgs.maven.buildMavenPackage {
-            pname = "keycloak-lists-plugin";
-            version = "1.0";
-
-            src = ./plugin;
-
-            mvnHash = "sha256-UaVCt6KIjR8i3vHVp5YWqu8zzM7mftXyrv5J2jxtw6Q=";
-
-            buildPhase = ''
-              mvn --offline package;
-            '';
-
-            installPhase = ''
-              mkdir -p $out/share/java
-              install -Dm644 target/*.jar $out/share/java
-            '';
           };
+
+          packages.default = pkgs.callPackage ./package.nix { };
+          packages.run = self.nixosConfigurations.test.config.microvm.declaredRunner;
         };
     in
     flake-utils.lib.eachDefaultSystem out // {
-      overlays.default = final: prev: {
+      nixosConfigurations.test = nixpkgs.lib.nixosSystem {
+        system = "x86_64-linux";
+        modules = [
+          ({ ... }: {
+            services.keycloak.plugins = [ self.packages.x86_64-linux.default ];
+          })
+          ./test-nixos.nix
+          microvm.nixosModules.microvm
+        ];
       };
+
+      overlays.default = final: prev: { };
     };
 
 }

package.nix

@@ -0,0 +1,18 @@
+{ maven }:
+maven.buildMavenPackage {
+  pname = "keycloak-lists-plugin";
+  version = "1.0";
+
+  src = ./plugin;
+
+  mvnHash = "sha256-UaVCt6KIjR8i3vHVp5YWqu8zzM7mftXyrv5J2jxtw6Q=";
+
+  buildPhase = ''
+    mvn --offline package;
+  '';
+
+  installPhase = ''
+    mkdir -p $out
+    install -Dm644 target/*.jar $out
+  '';
+}

plugin/src/main/java/systems/lix/keycloak/AllowBanCheck.java

@@ -1,4 +1,4 @@
-package lix.systems.keycloak;
+package systems.lix.keycloak;
 
 import jakarta.ws.rs.core.Response;
 import org.keycloak.authentication.AuthenticationFlowContext;
@@ -25,6 +25,9 @@ public class AllowBanCheck implements Authenticator {
         var attr = context.getUser().getFirstAttribute("githubId");
 
         if (attr == null) {
+            // We don't think this should be "attempted", because this must be
+            // a required authenticator, and we want to pass if we don't apply.
+            context.success();
             return;
         }
 

plugin/src/main/java/systems/lix/keycloak/AllowBanCheckFactory.java

@@ -1,4 +1,4 @@
-package lix.systems.keycloak;
+package systems.lix.keycloak;
 
 import org.keycloak.Config;
 import org.keycloak.authentication.Authenticator;

plugin/src/main/java/systems/lix/keycloak/AllowBansDB.java

@@ -1,4 +1,4 @@
-package lix.systems.keycloak;
+package systems.lix.keycloak;
 
 /**
  * A database of whether users are allow-listed or banned.

plugin/src/main/java/systems/lix/keycloak/FileAllowBansDB.java

@@ -1,4 +1,4 @@
-package lix.systems.keycloak;
+package systems.lix.keycloak;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

plugin/src/main/resources/META-INF/services/org.keycloak.authentication.AuthenticatorFactory

@@ -0,0 +1 @@
+systems.lix.keycloak.AllowBanCheckFactory

test-nixos.nix

@@ -0,0 +1,156 @@
+{ pkgs, lib, ... }:
+let
+  # Server we're hosting on.
+  host = "identity.test.lix.systems";
+
+  # Realm used for services.
+  realm = "lix-project";
+
+in
+{
+  users.users.root.password = "";
+  services.openssh.enable = true;
+  services.openssh.settings.PermitRootLogin = "yes";
+
+  services.keycloak = {
+    enable = true;
+
+    settings = {
+      hostname = host;
+
+      # Always talk through our reverse proxy.
+      http-port = 9091;
+      proxy = "edge";
+    };
+
+    # This will be immediately changed, so no harm in having it here.
+    initialAdminPassword = "Password1";
+
+    # Automatically manage our database.
+    database = {
+      createLocally = true;
+      # DO NOT DO THIS IN PROD
+      passwordFile = builtins.toFile "bad-db-password" "Password1";
+    };
+
+    settings = {
+      log-level = "INFO";
+      spi-authenticator-allow-ban-check-authenticator-dbpath = "/var/keycloak-allow-bans";
+    };
+  };
+
+  # Postgres server for the storage backend.
+  services.postgresql.enable = true;
+
+  # Create a static user, so we can set up our keys beforehand.
+  # This overrides the dynamic user creation in the base module config.
+  users.users.keycloak = {
+    isSystemUser = true;
+    group = "keycloak";
+  };
+  users.groups.keycloak = { };
+
+  # Reverse proxy our data over https.
+  networking.firewall.allowedTCPPorts = [ 80 443 ];
+  services.nginx = {
+    enable = true;
+
+    virtualHosts = {
+      "${host}" = {
+        forceSSL = true;
+        sslCertificate = "/var/lib/nginx/nc-selfsigned.crt";
+        sslCertificateKey = "/var/lib/nginx/nc-selfsigned.key";
+
+        locations."/" = {
+          proxyPass = "http://127.0.0.1:9091";
+          extraConfig = ''
+            proxy_ssl_server_name on;
+            proxy_pass_header Authorization;
+            proxy_set_header X-Forwarded-For $proxy_protocol_addr;
+            proxy_set_header X-Forwarded-Proto $scheme;
+            proxy_set_header Host $host;
+
+            proxy_busy_buffers_size   512k;
+            proxy_buffers   4 512k;
+            proxy_buffer_size   256k;
+
+            # Allow clients with Auth hardcoded to use our base path.
+            #
+            # XXX: ok so this is horrible. For some reason gerrit explodes if
+            # it receives a redirect when doing auth. But we need to redirect
+            # the browser to reuse sessions. Thus, user agent scanning.
+            if ($http_user_agent ~* "^Java.*$") {
+              rewrite ^/auth/(.*)$ /$1 last;
+            }
+            rewrite ^/auth/(.*)$ /$1 redirect;
+
+            # Hacks to make us compatible with authenticators that expect GitLab's format.
+            rewrite ^/realms/${realm}/protocol/openid-connect/api/v4/user$ /realms/${realm}/protocol/openid-connect/userinfo;
+            rewrite ^/realms/${realm}/protocol/openid-connect/oauth/authorize$ /realms/${realm}/protocol/openid-connect/auth?scope=openid%20email%20profile;
+            rewrite ^/realms/${realm}/protocol/openid-connect/oauth/token$ /realms/${realm}/protocol/openid-connect/token;
+          '';
+        };
+
+        # Forward our admin address to our default realm.
+        locations."= /admin".extraConfig = "return 302 https://${host}/admin/lix-project/console/;";
+        locations."= /superadmin".extraConfig = "return 302 https://${host}/admin/master/console/;";
+
+        # Forward our root address to the account management portal.
+        locations."= /".extraConfig = "return 302 https://${host}/realms/${realm}/account;";
+      };
+    };
+  };
+
+  systemd.services.cert-setup = {
+    wantedBy = [ "nginx.service" ];
+    before = [ "nginx.service" ];
+    serviceConfig = {
+      ConditionFileExists = "!/var/lib/nginx/nc-selfsigned.crt";
+      ExecStart = [
+        "${lib.getBin pkgs.openssl}/bin/openssl req -x509 -nodes -days 365 -newkey rsa:2048 -subj /CN=identity.test.lix.systems/ -keyout /var/lib/nginx/nc-selfsigned.key -out /var/lib/nginx/nc-selfsigned.crt"
+        "${lib.getBin pkgs.coreutils}/bin/chown nginx:nginx /var/lib/nginx/nc-selfsigned.key /var/lib/nginx/nc-selfsigned.crt"
+      ];
+    };
+  };
+
+  systemd.tmpfiles.rules = [
+    "d /var/lib/nginx 755 nginx nginx -"
+  ];
+
+  microvm = {
+    hypervisor = "qemu";
+    mem = 1024;
+    interfaces = [{
+      type = "user";
+      id = "microvm";
+      mac = "02:00:00:00:00:01";
+    }];
+
+    forwardPorts = [
+      {
+        from = "host";
+        guest.port = 443;
+        host.port = 4043;
+        proto = "tcp";
+      }
+      {
+        from = "host";
+        guest.port = 22;
+        host.port = 2022;
+        proto = "tcp";
+      }
+    ];
+
+    volumes = [{
+      mountPoint = "/var";
+      image = "var.img";
+      size = 256;
+    }];
+    shares = [{
+      proto = "9p";
+      tag = "ro-store";
+      source = "/nix/store";
+      mountPoint = "/nix/.ro-store";
+    }];
+  };
+}