Add ESP32 support for WPA2-EAP Enterprise WiFi authentication (#1080)

* Add config generation and validation to support various WPA2-EAP authentication methods.

Config generate validates that all the required parameters are set in valid combinations.
In the event of EAP-TLS, the private key is matched to the certificate to check for pasting errors.

Add EAPAuth struct to header.
Add eap_auth property to WiFiAP with getters/setters.

* Add C++ code for setting WPA2-EAP authentication.

* Fix config for x509 EAP-TLS authentication.

* Fix a few linting issues.

* Fix a couple more linting issues that only showed up in CI

* Remove stray character.

Co-authored-by: Guillermo Ruffino <glm.net@gmail.com>

esphome/components/wifi/__init__.py

@@ -1,3 +1,6 @@
+import logging
+from cryptography.hazmat.primitives.asymmetric import rsa, ec, ed448, ed25519
+
 import esphome.codegen as cg
 import esphome.config_validation as cv
 from esphome import automation
@@ -5,12 +8,15 @@ from esphome.automation import Condition
 from esphome.const import CONF_AP, CONF_BSSID, CONF_CHANNEL, CONF_DNS1, CONF_DNS2, CONF_DOMAIN, \
     CONF_FAST_CONNECT, CONF_GATEWAY, CONF_HIDDEN, CONF_ID, CONF_MANUAL_IP, CONF_NETWORKS, \
     CONF_PASSWORD, CONF_POWER_SAVE_MODE, CONF_REBOOT_TIMEOUT, CONF_SSID, CONF_STATIC_IP, \
-    CONF_SUBNET, CONF_USE_ADDRESS, CONF_PRIORITY
+    CONF_SUBNET, CONF_USE_ADDRESS, CONF_PRIORITY, CONF_IDENTITY, CONF_CERTIFICATE_AUTHORITY, \
+    CONF_CERTIFICATE, CONF_KEY, CONF_USERNAME, CONF_EAP
 from esphome.core import CORE, HexInt, coroutine_with_priority
+_LOGGER = logging.getLogger(__name__)
 
 AUTO_LOAD = ['network']
 
 wifi_ns = cg.esphome_ns.namespace('wifi')
+EAPAuth = wifi_ns.struct('EAPAuth')
 IPAddress = cg.global_ns.class_('IPAddress')
 ManualIP = wifi_ns.struct('ManualIP')
 WiFiComponent = wifi_ns.class_('WiFiComponent', cg.Component)
@@ -36,6 +42,55 @@ def validate_password(value):
     return value
 
 
+def validate_eap(value):
+    if CONF_USERNAME in value:
+        if CONF_IDENTITY not in value:
+            _LOGGER.info("EAP 'identity:' is not set, assuming username.")
+            value[CONF_IDENTITY] = value[CONF_USERNAME]
+        if CONF_PASSWORD not in value:
+            raise cv.Invalid("You cannot use the EAP 'username:' option without a 'password:'. "
+                             "Please provide the 'password:' key")
+    if CONF_CERTIFICATE in value or CONF_KEY in value:
+        if CONF_CERTIFICATE not in value and CONF_KEY not in value:
+            raise cv.Invalid("You have provided an EAP 'certificate:' or 'key:' without providing "
+                             "the other. Please check you have provided both.")
+        # Check the key is valid and for this certificate, just to check the user hasn't pasted
+        # the wrong thing. I write this after I spent a while debugging that exact issue.
+        # This may require a password to decrypt to key, so we should verify that at the same time.
+        certPw = None
+        if CONF_PASSWORD in value:
+            certPw = value[CONF_PASSWORD]
+
+        cert = cv.load_certificate(value[CONF_CERTIFICATE])
+        try:
+            key = cv.load_key(value[CONF_KEY], certPw)
+        except ValueError as e:
+            raise cv.Invalid(
+                "There was an error with the EAP 'password:' provided for 'key:' :%s" % e
+            )
+        except TypeError as e:
+            raise cv.Invalid("There was an error with the EAP 'key:' provided :%s" % e)
+
+        if isinstance(key, rsa.RSAPrivateKey):
+            if key.public_key().public_numbers() != cert.public_key().public_numbers():
+                raise cv.Invalid("The provided EAP 'key:' does not match the 'certificate:'")
+        elif isinstance(key, ec.EllipticCurvePrivateKey):
+            if key.public_key().public_numbers() != cert.public_key().public_numbers():
+                raise cv.Invalid("The provided EAP 'key:' does not match the 'certificate:'")
+        elif isinstance(key, ed448.Ed448PrivateKey):
+            if key.public_key() != cert:
+                raise cv.Invalid("The provided EAP 'key:' does not match the 'certificate:'")
+        elif isinstance(key, ed25519.Ed25519PrivateKey):
+            if key.public_key() != cert:
+                raise cv.Invalid("The provided EAP 'key:' does not match the 'certificate:'")
+        else:
+            _LOGGER.warning(
+                "Unrecognised EAP 'certificate:' 'key:' pair format: %s. Proceed with caution!",
+                type(key)
+            )
+    return value
+
+
 def validate_channel(value):
     value = cv.positive_int(value)
     if value < 1:
@@ -56,6 +111,15 @@ STA_MANUAL_IP_SCHEMA = AP_MANUAL_IP_SCHEMA.extend({
     cv.Optional(CONF_DNS2, default="0.0.0.0"): cv.ipv4,
 })
 
+EAP_AUTH_SCHEMA = cv.Schema({
+    cv.Optional(CONF_IDENTITY): cv.string_strict,
+    cv.Optional(CONF_USERNAME): cv.string_strict,
+    cv.Optional(CONF_PASSWORD): cv.string_strict,
+    cv.Optional(CONF_CERTIFICATE_AUTHORITY): cv.certificate,
+    cv.Optional(CONF_CERTIFICATE): cv.certificate,
+    cv.Optional(CONF_KEY): cv.string_strict,
+})
+
 WIFI_NETWORK_BASE = cv.Schema({
     cv.GenerateID(): cv.declare_id(WiFiAP),
     cv.Optional(CONF_SSID): cv.ssid,
@@ -73,6 +137,7 @@ WIFI_NETWORK_STA = WIFI_NETWORK_BASE.extend({
     cv.Optional(CONF_BSSID): cv.mac_address,
     cv.Optional(CONF_HIDDEN): cv.boolean,
     cv.Optional(CONF_PRIORITY, default=0.0): cv.float_,
+    cv.Optional(CONF_EAP): EAP_AUTH_SCHEMA,
 })
 
 
@@ -93,6 +158,10 @@ def validate(config):
         raise cv.Invalid("Please specify at least an SSID or an Access Point "
                          "to create.")
 
+    for network in config[CONF_NETWORKS]:
+        if CONF_EAP in network:
+            network[CONF_EAP] = validate_eap(network[CONF_EAP])
+
     if config.get(CONF_FAST_CONNECT, False):
         networks = config.get(CONF_NETWORKS, [])
         if not networks:
@@ -118,6 +187,7 @@ CONFIG_SCHEMA = cv.All(cv.Schema({
     cv.Optional(CONF_SSID): cv.ssid,
     cv.Optional(CONF_PASSWORD): validate_password,
     cv.Optional(CONF_MANUAL_IP): STA_MANUAL_IP_SCHEMA,
+    cv.Optional(CONF_EAP): EAP_AUTH_SCHEMA,
 
     cv.Optional(CONF_AP): WIFI_NETWORK_AP,
     cv.Optional(CONF_DOMAIN, default='.local'): cv.domain_name,
@@ -133,6 +203,20 @@ CONFIG_SCHEMA = cv.All(cv.Schema({
 }), validate)
 
 
+def eap_auth(config):
+    if config is None:
+        return None
+    return cg.StructInitializer(
+        EAPAuth,
+        ('identity', config.get(CONF_IDENTITY, "")),
+        ('username', config.get(CONF_USERNAME, "")),
+        ('password', config.get(CONF_PASSWORD, "")),
+        ('ca_cert', config.get(CONF_CERTIFICATE_AUTHORITY, "")),
+        ('client_cert', config.get(CONF_CERTIFICATE, "")),
+        ('client_key', config.get(CONF_KEY, "")),
+    )
+
+
 def safe_ip(ip):
     if ip is None:
         return IPAddress(0, 0, 0, 0)
@@ -158,6 +242,8 @@ def wifi_network(config, static_ip):
         cg.add(ap.set_ssid(config[CONF_SSID]))
     if CONF_PASSWORD in config:
         cg.add(ap.set_password(config[CONF_PASSWORD]))
+    if CONF_EAP in config:
+        cg.add(ap.set_eap(eap_auth(config[CONF_EAP])))
     if CONF_BSSID in config:
         cg.add(ap.set_bssid([HexInt(i) for i in config[CONF_BSSID].parts]))
     if CONF_HIDDEN in config:

esphome/components/wifi/wifi_component.cpp

@@ -541,12 +541,14 @@ void WiFiAP::set_ssid(const std::string &ssid) { this->ssid_ = ssid; }
 void WiFiAP::set_bssid(bssid_t bssid) { this->bssid_ = bssid; }
 void WiFiAP::set_bssid(optional<bssid_t> bssid) { this->bssid_ = bssid; }
 void WiFiAP::set_password(const std::string &password) { this->password_ = password; }
+void WiFiAP::set_eap(optional<EAPAuth> eap_auth) { this->eap_ = eap_auth; }
 void WiFiAP::set_channel(optional<uint8_t> channel) { this->channel_ = channel; }
 void WiFiAP::set_manual_ip(optional<ManualIP> manual_ip) { this->manual_ip_ = manual_ip; }
 void WiFiAP::set_hidden(bool hidden) { this->hidden_ = hidden; }
 const std::string &WiFiAP::get_ssid() const { return this->ssid_; }
 const optional<bssid_t> &WiFiAP::get_bssid() const { return this->bssid_; }
 const std::string &WiFiAP::get_password() const { return this->password_; }
+const optional<EAPAuth> &WiFiAP::get_eap() const { return this->eap_; }
 const optional<uint8_t> &WiFiAP::get_channel() const { return this->channel_; }
 const optional<ManualIP> &WiFiAP::get_manual_ip() const { return this->manual_ip_; }
 bool WiFiAP::get_hidden() const { return this->hidden_; }

esphome/components/wifi/wifi_component.h

@@ -57,6 +57,16 @@ struct ManualIP {
   IPAddress dns2;  ///< The second DNS server. 0.0.0.0 for default.
 };
 
+struct EAPAuth {
+  std::string identity;  // required for all auth types
+  std::string username;
+  std::string password;
+  char *ca_cert;  // optionally verify authentication server
+  // used for EAP-TLS
+  char *client_cert;
+  char *client_key;
+};
+
 using bssid_t = std::array<uint8_t, 6>;
 
 class WiFiAP {
@@ -65,6 +75,7 @@ class WiFiAP {
   void set_bssid(bssid_t bssid);
   void set_bssid(optional<bssid_t> bssid);
   void set_password(const std::string &password);
+  void set_eap(optional<EAPAuth> eap_auth);
   void set_channel(optional<uint8_t> channel);
   void set_priority(float priority) { priority_ = priority; }
   void set_manual_ip(optional<ManualIP> manual_ip);
@@ -72,6 +83,7 @@ class WiFiAP {
   const std::string &get_ssid() const;
   const optional<bssid_t> &get_bssid() const;
   const std::string &get_password() const;
+  const optional<EAPAuth> &get_eap() const;
   const optional<uint8_t> &get_channel() const;
   float get_priority() const { return priority_; }
   const optional<ManualIP> &get_manual_ip() const;
@@ -81,6 +93,7 @@ class WiFiAP {
   std::string ssid_;
   optional<bssid_t> bssid_;
   std::string password_;
+  optional<EAPAuth> eap_;
   optional<uint8_t> channel_;
   float priority_{0};
   optional<ManualIP> manual_ip_;

esphome/components/wifi/wifi_component_esp32.cpp

@@ -6,6 +6,7 @@
 
 #include <utility>
 #include <algorithm>
+#include <esp_wpa2.h>
 #include "lwip/err.h"
 #include "lwip/dns.h"
 
@@ -187,6 +188,51 @@ bool WiFiComponent::wifi_sta_connect_(WiFiAP ap) {
     return false;
   }
 
+  // setup enterprise authentication if required
+  if (ap.get_eap().has_value()) {
+    // note: all certificates and keys have to be null terminated. Lengths are appended by +1 to include \0.
+    EAPAuth eap = ap.get_eap().value();
+    err = esp_wifi_sta_wpa2_ent_set_identity((uint8_t *) eap.identity.c_str(), eap.identity.length());
+    if (err != ESP_OK) {
+      ESP_LOGV(TAG, "esp_wifi_sta_wpa2_ent_set_identity failed! %d", err);
+    }
+    int ca_cert_len = strlen(eap.ca_cert);
+    int client_cert_len = strlen(eap.client_cert);
+    int client_key_len = strlen(eap.client_key);
+    if (ca_cert_len) {
+      err = esp_wifi_sta_wpa2_ent_set_ca_cert((uint8_t *) eap.ca_cert, ca_cert_len + 1);
+      if (err != ESP_OK) {
+        ESP_LOGV(TAG, "esp_wifi_sta_wpa2_ent_set_ca_cert failed! %d", err);
+      }
+    }
+    // workout what type of EAP this is
+    // validation is not required as the config tool has already validated it
+    if (client_cert_len && client_key_len) {
+      // if we have certs, this must be EAP-TLS
+      err = esp_wifi_sta_wpa2_ent_set_cert_key((uint8_t *) eap.client_cert, client_cert_len + 1,
+                                               (uint8_t *) eap.client_key, client_key_len + 1,
+                                               (uint8_t *) eap.password.c_str(), strlen(eap.password.c_str()));
+      if (err != ESP_OK) {
+        ESP_LOGV(TAG, "esp_wifi_sta_wpa2_ent_set_cert_key failed! %d", err);
+      }
+    } else {
+      // in the absence of certs, assume this is username/password based
+      err = esp_wifi_sta_wpa2_ent_set_username((uint8_t *) eap.username.c_str(), eap.username.length());
+      if (err != ESP_OK) {
+        ESP_LOGV(TAG, "esp_wifi_sta_wpa2_ent_set_username failed! %d", err);
+      }
+      err = esp_wifi_sta_wpa2_ent_set_password((uint8_t *) eap.password.c_str(), eap.password.length());
+      if (err != ESP_OK) {
+        ESP_LOGV(TAG, "esp_wifi_sta_wpa2_ent_set_password failed! %d", err);
+      }
+    }
+    esp_wpa2_config_t wpa2Config = WPA2_CONFIG_INIT_DEFAULT();
+    err = esp_wifi_sta_wpa2_ent_enable(&wpa2Config);
+    if (err != ESP_OK) {
+      ESP_LOGV(TAG, "esp_wifi_sta_wpa2_ent_enable failed! %d", err);
+    }
+  }
+
   this->wifi_apply_hostname_();
 
   err = esp_wifi_connect();

esphome/config_validation.py

@@ -10,6 +10,10 @@ from string import ascii_letters, digits
 
 import voluptuous as vol
 
+from cryptography import x509
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives.serialization import load_pem_private_key
+
 from esphome import core
 from esphome.const import CONF_AVAILABILITY, CONF_COMMAND_TOPIC, CONF_DISCOVERY, CONF_ID, \
     CONF_INTERNAL, CONF_NAME, CONF_PAYLOAD_AVAILABLE, CONF_PAYLOAD_NOT_AVAILABLE, \
@@ -717,6 +721,25 @@ def domain_name(value):
     return value
 
 
+def load_certificate(value):
+    return x509.load_pem_x509_certificate(value.encode('UTF-8'), default_backend())
+
+
+def load_key(value, password):
+    if password:
+        password = password.encode("UTF-8")
+    return load_pem_private_key(value.encode('UTF-8'), password, default_backend())
+
+
+def certificate(value):
+    value = string_strict(value)
+    try:
+        load_certificate(value)  # raises ValueError
+        return value
+    except ValueError:
+        return Invalid("Invalid certificate")
+
+
 def ssid(value):
     value = string_strict(value)
     if not value:

esphome/const.py

@@ -76,6 +76,8 @@ CONF_CALIBRATION = 'calibration'
 CONF_CAPACITANCE = 'capacitance'
 CONF_CARRIER_DUTY_PERCENT = 'carrier_duty_percent'
 CONF_CARRIER_FREQUENCY = 'carrier_frequency'
+CONF_CERTIFICATE = "certificate"
+CONF_CERTIFICATE_AUTHORITY = "certificate_authority"
 CONF_CHANGE_MODE_EVERY = 'change_mode_every'
 CONF_CHANNEL = 'channel'
 CONF_CHANNELS = 'channels'
@@ -146,6 +148,7 @@ CONF_DRY_ACTION = 'dry_action'
 CONF_DRY_MODE = 'dry_mode'
 CONF_DUMP = 'dump'
 CONF_DURATION = 'duration'
+CONF_EAP = 'eap'
 CONF_ECHO_PIN = 'echo_pin'
 CONF_EFFECT = 'effect'
 CONF_EFFECTS = 'effects'
@@ -211,6 +214,7 @@ CONF_I2C = 'i2c'
 CONF_I2C_ID = 'i2c_id'
 CONF_ICON = 'icon'
 CONF_ID = 'id'
+CONF_IDENTITY = 'identity'
 CONF_IDLE = 'idle'
 CONF_IDLE_ACTION = 'idle_action'
 CONF_IDLE_LEVEL = 'idle_level'
@@ -238,6 +242,7 @@ CONF_JS_URL = 'js_url'
 CONF_JVC = 'jvc'
 CONF_KEEP_ON_TIME = 'keep_on_time'
 CONF_KEEPALIVE = 'keepalive'
+CONF_KEY = 'key'
 CONF_LAMBDA = 'lambda'
 CONF_LEVEL = 'level'
 CONF_LG = 'lg'

requirements.txt

@@ -10,4 +10,5 @@ pyserial==3.4
 ifaddr==0.1.6
 platformio==4.3.3
 esptool==2.8
+cryptography==2.9.2
 click==7.1.2

requirements_test.txt

@@ -10,6 +10,7 @@ pyserial==3.4
 ifaddr==0.1.6
 platformio==4.3.3
 esptool==2.8
+cryptography==2.9.2
 
 pylint==2.5.0
 flake8==3.7.9