diff mbox

[RFC,PATCHv8] Use radius supplied Passphrase for WPA-PSK

Message ID 20111206172135.GA11480@dynamic.fami-braun.de
State Superseded
Headers show

Commit Message

michael-dev Dec. 6, 2011, 5:21 p.m. UTC
Hi,

I wanted to use the per-device-PSK (WPA) feature in conjunction with a radius server that does the authorization checking and should supply the psk.

This patch addresses the previous comments by
 - using Tunnel-Password instead of a plaintext, hostapd specific radius vendor attribute,
 - moving the psk generation out of radius.c,
 - removing the superflous = 0 assignment,
 - removing direkt psk supply for simplicity.

Please find a patch against git head attached that compiles fine and has been tested on x86.

To use this, one needs to enable the macaddr_acl=2 setting and have wpa_psk_radius=1 in hostapd.conf.
The radius server then just needs to supply the Tunnel-Password attribute on the access requests.
The Service-Type radius attribute is used to easily differentiate between PSK reqests and EAP requests.

Regards,                                                                                                                                                                                                       
 M. Braun
diff mbox

Patch

commit 04460f68f9c567453ed392dc7e4b3eb2bcfb5cc6
Author: Michael Braun <michael-dev@fami-braun.de>
Date:   Tue Dec 6 17:41:23 2011 +0100

    Enabled hostapd to fetch WPA Passphrase using RADIUS Tunnel-Password attribute.
    
    Signed-hostap: Michael Braun <michael-dev@fami-braun.de>

diff --git a/hostapd/README b/hostapd/README
index a211cdd..a94bc2a 100644
--- a/hostapd/README
+++ b/hostapd/README
@@ -350,6 +350,11 @@  TODO
 #wpa_psk=0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef
 #wpa_passphrase=secret passphrase
 
+# Optionally, WPA PSKs can be read from RADIUS (to be used with macaddr_acl set to RADIUS)
+# 0 no
+# 1 may (falls back to the above if no radius attribute is found)
+#wpa_psk_radius=0
+
 # Set of accepted key management algorithms (WPA-PSK, WPA-EAP, or both). The
 # entries are separated with a space.
 #wpa_key_mgmt=WPA-PSK WPA-EAP
diff --git a/hostapd/config_file.c b/hostapd/config_file.c
index 5eb7b49..7e226c6 100644
--- a/hostapd/config_file.c
+++ b/hostapd/config_file.c
@@ -1052,7 +1052,7 @@  static int hostapd_config_check_bss(struct hostapd_bss_config *bss,
 
 	if (bss->wpa && (bss->wpa_key_mgmt & WPA_KEY_MGMT_PSK) &&
 	    bss->ssid.wpa_psk == NULL && bss->ssid.wpa_passphrase == NULL &&
-	    bss->ssid.wpa_psk_file == NULL) {
+	    bss->ssid.wpa_psk_file == NULL && bss->wpa_psk_radius == 0) {
 		wpa_printf(MSG_ERROR, "WPA-PSK enabled, but PSK or passphrase "
 			   "is not configured.");
 		return -1;
@@ -1629,6 +1629,8 @@  struct hostapd_config * hostapd_config_read(const char *fname)
 				hostapd_config_parse_key_mgmt(line, pos);
 			if (bss->wpa_key_mgmt == -1)
 				errors++;
+		} else if (os_strcmp(buf, "wpa_psk_radius") == 0) {
+			bss->wpa_psk_radius = atoi(pos);
 		} else if (os_strcmp(buf, "wpa_pairwise") == 0) {
 			bss->wpa_pairwise =
 				hostapd_config_parse_cipher(line, pos);
diff --git a/hostapd/hostapd.conf b/hostapd/hostapd.conf
index 2a54518..3af8ac6 100644
--- a/hostapd/hostapd.conf
+++ b/hostapd/hostapd.conf
@@ -700,6 +700,11 @@  own_ip_addr=127.0.0.1
 # configuration reloads.
 #wpa_psk_file=/etc/hostapd.wpa_psk
 
+# Optionally, WPA PSKs can be read from RADIUS (to be used with macaddr_acl set to RADIUS)
+# 0 no
+# 1 may (falls back to the above if no radius attribute is found)
+wpa_psk_radius=1
+
 # Set of accepted key management algorithms (WPA-PSK, WPA-EAP, or both). The
 # entries are separated with a space. WPA-PSK-SHA256 and WPA-EAP-SHA256 can be
 # added to enable SHA256-based stronger algorithms.
diff --git a/src/ap/ap_config.h b/src/ap/ap_config.h
index 2b201df..c1b6c73 100644
--- a/src/ap/ap_config.h
+++ b/src/ap/ap_config.h
@@ -219,6 +219,7 @@  struct hostapd_bss_config {
 	/* dot11AssociationSAQueryRetryTimeout (in TUs) */
 	int assoc_sa_query_retry_timeout;
 #endif /* CONFIG_IEEE80211W */
+	int wpa_psk_radius;
 	int wpa_pairwise;
 	int wpa_group;
 	int wpa_group_rekey;
diff --git a/src/ap/ieee802_11.c b/src/ap/ieee802_11.c
index 0352599..ade5c00 100644
--- a/src/ap/ieee802_11.c
+++ b/src/ap/ieee802_11.c
@@ -313,6 +313,8 @@  static void handle_auth(struct hostapd_data *hapd,
 	const u8 *challenge = NULL;
 	u32 session_timeout, acct_interim_interval;
 	int vlan_id = 0;
+        u8 psk[PMK_LEN];
+	int has_psk = 0;
 	u8 resp_ies[2 + WLAN_AUTH_CHALLENGE_LEN];
 	size_t resp_ies_len = 0;
 
@@ -375,7 +377,8 @@  static void handle_auth(struct hostapd_data *hapd,
 
 	res = hostapd_allowed_address(hapd, mgmt->sa, (u8 *) mgmt, len,
 				      &session_timeout,
-				      &acct_interim_interval, &vlan_id);
+				      &acct_interim_interval, &vlan_id, psk, &has_psk);
+
 	if (res == HOSTAPD_ACL_REJECT) {
 		printf("Station " MACSTR " not allowed to authenticate.\n",
 		       MAC2STR(mgmt->sa));
@@ -412,6 +415,12 @@  static void handle_auth(struct hostapd_data *hapd,
 		hostapd_logger(hapd, sta->addr, HOSTAPD_MODULE_RADIUS,
 			       HOSTAPD_LEVEL_INFO, "VLAN ID %d", sta->vlan_id);
 	}
+	if (has_psk && hapd->conf->wpa_psk_radius == 1) {
+		sta->psk = os_zalloc(PMK_LEN);
+		os_memcpy(sta->psk, psk, PMK_LEN);
+	} else {
+		sta->psk = 0;
+	}
 
 	sta->flags &= ~WLAN_STA_PREAUTH;
 	ieee802_1x_notify_pre_auth(sta->eapol_sm, 0);
diff --git a/src/ap/ieee802_11_auth.c b/src/ap/ieee802_11_auth.c
index 9b558fa..f5672fb 100644
--- a/src/ap/ieee802_11_auth.c
+++ b/src/ap/ieee802_11_auth.c
@@ -28,6 +28,7 @@ 
 #include "ap_drv_ops.h"
 #include "ieee802_11.h"
 #include "ieee802_11_auth.h"
+#include "crypto/sha1.h"
 
 #define RADIUS_ACL_TIMEOUT 30
 
@@ -40,6 +41,8 @@  struct hostapd_cached_radius_acl {
 	u32 session_timeout;
 	u32 acct_interim_interval;
 	int vlan_id;
+	int has_psk;
+        u8 psk[PMK_LEN];
 };
 
 
@@ -68,7 +71,7 @@  static void hostapd_acl_cache_free(struct hostapd_cached_radius_acl *acl_cache)
 
 static int hostapd_acl_cache_get(struct hostapd_data *hapd, const u8 *addr,
 				 u32 *session_timeout,
-				 u32 *acct_interim_interval, int *vlan_id)
+				 u32 *acct_interim_interval, int *vlan_id, u8* psk, int* has_psk)
 {
 	struct hostapd_cached_radius_acl *entry;
 	struct os_time now;
@@ -89,6 +92,10 @@  static int hostapd_acl_cache_get(struct hostapd_data *hapd, const u8 *addr,
 					entry->acct_interim_interval;
 			if (vlan_id)
 				*vlan_id = entry->vlan_id;
+                        if (psk)
+		                os_memcpy(psk, entry->psk, PMK_LEN);
+			if (has_psk)
+				*has_psk = entry->has_psk;
 			return entry->accepted;
 		}
 
@@ -184,6 +191,12 @@  static int hostapd_radius_acl_query(struct hostapd_data *hapd, const u8 *addr,
 		goto fail;
 	}
 
+	if (!radius_msg_add_attr_int32(msg, RADIUS_ATTR_SERVICE_TYPE,
+				       RADIUS_SERVICE_TYPE_OUTBOUND)) {
+		wpa_printf(MSG_DEBUG, "Could not add Service-Type");
+		goto fail;
+	}
+
 	os_snprintf(buf, sizeof(buf), "CONNECT 11Mbps 802.11b");
 	if (!radius_msg_add_attr(msg, RADIUS_ATTR_CONNECT_INFO,
 				 (u8 *) buf, os_strlen(buf))) {
@@ -214,7 +227,7 @@  static int hostapd_radius_acl_query(struct hostapd_data *hapd, const u8 *addr,
  */
 int hostapd_allowed_address(struct hostapd_data *hapd, const u8 *addr,
 			    const u8 *msg, size_t len, u32 *session_timeout,
-			    u32 *acct_interim_interval, int *vlan_id)
+			    u32 *acct_interim_interval, int *vlan_id, u8* psk, int* has_psk)
 {
 	if (session_timeout)
 		*session_timeout = 0;
@@ -222,6 +235,10 @@  int hostapd_allowed_address(struct hostapd_data *hapd, const u8 *addr,
 		*acct_interim_interval = 0;
 	if (vlan_id)
 		*vlan_id = 0;
+        if (has_psk)
+		*has_psk = 0;
+	if (psk)
+		os_memset(psk, 0, PMK_LEN);
 
 	if (hostapd_maclist_found(hapd->conf->accept_mac,
 				  hapd->conf->num_accept_mac, addr, vlan_id))
@@ -246,7 +263,7 @@  int hostapd_allowed_address(struct hostapd_data *hapd, const u8 *addr,
 		/* Check whether ACL cache has an entry for this station */
 		int res = hostapd_acl_cache_get(hapd, addr, session_timeout,
 						acct_interim_interval,
-						vlan_id);
+						vlan_id, psk, has_psk);
 		if (res == HOSTAPD_ACL_ACCEPT ||
 		    res == HOSTAPD_ACL_ACCEPT_TIMEOUT)
 			return res;
@@ -456,6 +473,21 @@  hostapd_acl_recv_radius(struct radius_msg *msg, struct radius_msg *req,
 		}
 
 		cache->vlan_id = radius_msg_get_vlanid(msg);
+
+		int passphraselen;
+		char* passphrase = radius_msg_get_tunnel_password(msg, &passphraselen, hapd->conf->radius->auth_server->shared_secret, hapd->conf->radius->auth_server->shared_secret_len, req);
+		cache->has_psk = (passphrase != NULL);
+		if (passphrase != NULL) {
+			/** passphrase does not contain the NULL termination. Add it here as pbkdf2_sha1 requires it. */
+			char* strpassphrase = os_zalloc(passphraselen+1);
+			os_memcpy(strpassphrase, passphrase, passphraselen);
+			pbkdf2_sha1(strpassphrase, hapd->conf->ssid.ssid, hapd->conf->ssid.ssid_len, 4096, cache->psk, PMK_LEN);
+			os_free(passphrase); passphrase = NULL;
+			os_free(strpassphrase); strpassphrase = NULL;
+		}
+
+		if (hapd->conf->wpa_psk_radius == 1 && cache->psk == NULL)
+			cache->accepted = HOSTAPD_ACL_REJECT;
 	} else
 		cache->accepted = HOSTAPD_ACL_REJECT;
 	cache->next = hapd->acl_cache;
diff --git a/src/ap/ieee802_11_auth.h b/src/ap/ieee802_11_auth.h
index b2971e5..ee451f9 100644
--- a/src/ap/ieee802_11_auth.h
+++ b/src/ap/ieee802_11_auth.h
@@ -24,7 +24,7 @@  enum {
 
 int hostapd_allowed_address(struct hostapd_data *hapd, const u8 *addr,
 			    const u8 *msg, size_t len, u32 *session_timeout,
-			    u32 *acct_interim_interval, int *vlan_id);
+			    u32 *acct_interim_interval, int *vlan_id, u8* psk, int* has_psk);
 int hostapd_acl_init(struct hostapd_data *hapd);
 void hostapd_acl_deinit(struct hostapd_data *hapd);
 
diff --git a/src/ap/ieee802_1x.c b/src/ap/ieee802_1x.c
index 18ee747..45509b4 100644
--- a/src/ap/ieee802_1x.c
+++ b/src/ap/ieee802_1x.c
@@ -509,6 +509,12 @@  static void ieee802_1x_encapsulate_radius(struct hostapd_data *hapd,
 		goto fail;
 	}
 
+	if (!radius_msg_add_attr_int32(msg, RADIUS_ATTR_SERVICE_TYPE,
+				       RADIUS_SERVICE_TYPE_FRAMED)) {
+		printf("Could not add Service-Type\n");
+		goto fail;
+	}
+
 	if (sta->flags & WLAN_STA_PREAUTH) {
 		os_strlcpy(buf, "IEEE 802.11i Pre-Authentication",
 			   sizeof(buf));
diff --git a/src/ap/sta_info.c b/src/ap/sta_info.c
index a9981cc..bcea28e 100644
--- a/src/ap/sta_info.c
+++ b/src/ap/sta_info.c
@@ -228,6 +228,7 @@  void ap_free_sta(struct hostapd_data *hapd, struct sta_info *sta)
 	wpabuf_free(sta->p2p_ie);
 
 	os_free(sta->ht_capabilities);
+	os_free(sta->psk);
 
 	os_free(sta);
 }
diff --git a/src/ap/sta_info.h b/src/ap/sta_info.h
index 3ad00e2..7514af6 100644
--- a/src/ap/sta_info.h
+++ b/src/ap/sta_info.h
@@ -98,6 +98,7 @@  struct sta_info {
 	struct hostapd_ssid *ssid_probe; /* SSID selection based on ProbeReq */
 
 	int vlan_id;
+	u8* psk;
 
 	struct ieee80211_ht_capabilities *ht_capabilities;
 
diff --git a/src/ap/wpa_auth.h b/src/ap/wpa_auth.h
index ce2751e..9af82dd 100644
--- a/src/ap/wpa_auth.h
+++ b/src/ap/wpa_auth.h
@@ -132,6 +132,7 @@  struct wpa_auth_config {
 	int wpa;
 	int wpa_key_mgmt;
 	int wpa_pairwise;
+	int wpa_psk_radius;
 	int wpa_group;
 	int wpa_group_rekey;
 	int wpa_strict_rekey;
diff --git a/src/ap/wpa_auth_glue.c b/src/ap/wpa_auth_glue.c
index 1e9d422..7ef0c07 100644
--- a/src/ap/wpa_auth_glue.c
+++ b/src/ap/wpa_auth_glue.c
@@ -39,6 +39,7 @@  static void hostapd_wpa_auth_conf(struct hostapd_bss_config *conf,
 	wconf->wpa = conf->wpa;
 	wconf->wpa_key_mgmt = conf->wpa_key_mgmt;
 	wconf->wpa_pairwise = conf->wpa_pairwise;
+	wconf->wpa_psk_radius = conf->wpa_psk_radius;
 	wconf->wpa_group = conf->wpa_group;
 	wconf->wpa_group_rekey = conf->wpa_group_rekey;
 	wconf->wpa_strict_rekey = conf->wpa_strict_rekey;
@@ -186,7 +187,10 @@  static const u8 * hostapd_wpa_auth_get_psk(void *ctx, const u8 *addr,
 					   const u8 *prev_psk)
 {
 	struct hostapd_data *hapd = ctx;
-	return hostapd_get_psk(hapd->conf, addr, prev_psk);
+	struct sta_info *sta = ap_get_sta(hapd, addr);
+	if (sta == NULL || sta->psk == NULL)
+		return hostapd_get_psk(hapd->conf, addr, prev_psk);
+	return sta->psk;
 }
 
 
diff --git a/src/radius/radius.c b/src/radius/radius.c
index fb03a25..5f4f03e 100644
--- a/src/radius/radius.c
+++ b/src/radius/radius.c
@@ -173,6 +173,7 @@  static struct radius_attr_type radius_attrs[] =
 	{ RADIUS_ATTR_USER_PASSWORD, "User-Password", RADIUS_ATTR_UNDIST },
 	{ RADIUS_ATTR_NAS_IP_ADDRESS, "NAS-IP-Address", RADIUS_ATTR_IP },
 	{ RADIUS_ATTR_NAS_PORT, "NAS-Port", RADIUS_ATTR_INT32 },
+	{ RADIUS_ATTR_SERVICE_TYPE, "Service-Type", RADIUS_ATTR_INT32 },
 	{ RADIUS_ATTR_FRAMED_MTU, "Framed-MTU", RADIUS_ATTR_INT32 },
 	{ RADIUS_ATTR_REPLY_MESSAGE, "Reply-Message", RADIUS_ATTR_TEXT },
 	{ RADIUS_ATTR_STATE, "State", RADIUS_ATTR_UNDIST },
@@ -218,6 +219,8 @@  static struct radius_attr_type radius_attrs[] =
 	{ RADIUS_ATTR_TUNNEL_TYPE, "Tunnel-Type", RADIUS_ATTR_HEXDUMP },
 	{ RADIUS_ATTR_TUNNEL_MEDIUM_TYPE, "Tunnel-Medium-Type",
 	  RADIUS_ATTR_HEXDUMP },
+	{ RADIUS_ATTR_TUNNEL_PASSWORD, "Tunnel-Password",
+	  RADIUS_ATTR_UNDIST },
 	{ RADIUS_ATTR_CONNECT_INFO, "Connect-Info", RADIUS_ATTR_TEXT },
 	{ RADIUS_ATTR_EAP_MESSAGE, "EAP-Message", RADIUS_ATTR_UNDIST },
 	{ RADIUS_ATTR_MESSAGE_AUTHENTICATOR, "Message-Authenticator",
@@ -1275,6 +1278,92 @@  int radius_msg_get_vlanid(struct radius_msg *msg)
 }
 
 
+/**
+ * radius_msg_get_tunnel_password - Parse RADIUS attribute Tunnel-Password
+ * @msg: RADIUS message
+ * @passwordlen: length of returned password
+ * Returns: pointer to password (free with os_free) or NULL
+ */
+char* radius_msg_get_tunnel_password(struct radius_msg *msg, int* keylen, const u8 *secret, size_t secret_len, struct radius_msg *sent_msg)
+{
+	/* generic radius fields */
+	u8 *buf;
+	unsigned int buflen;
+
+	/* fields of tunnel-password */
+	u8 *tag;
+	u8 *salt;
+	u8* str;
+
+	/* helper vars for md5 */
+	const u8 *addr[3];
+	size_t len[3];
+	u8 hash[16];
+        /* helper var for iteration blocks */
+	u8* pos;
+	int i;
+
+	/* check packet */
+	if (radius_msg_get_attr_ptr(msg, RADIUS_ATTR_TUNNEL_PASSWORD, &buf, &buflen, NULL) < 0) return NULL;
+	if ((buflen <= 3) || (buflen % 16 != 3)) {
+		return NULL;
+	}
+
+	/* init pointers */
+	tag  = buf;
+	salt = buf + 1;
+	str  = buf + 3;
+
+	/* decrypt blocks */
+	pos = buf + buflen - 16; // last block
+	while (pos >= str + 16) { // all but the first block
+		addr[0] = secret;
+		len[0] = secret_len;
+		addr[1] = pos - 16;
+		len[1] = 16;
+		md5_vector(2, addr, len, hash);
+
+		for (i = 0; i < 16; i++)
+			pos[i] ^= hash[i];
+
+		pos -= 16;
+	}
+
+	/* decrypt first block */
+	if (str != pos) {
+		return NULL;
+	}
+	addr[0] = secret;
+	len[0] = secret_len;
+	addr[1] = sent_msg->hdr->authenticator;
+	len[1] = 16;
+	addr[2] = salt;
+	len[2] = 2;
+	md5_vector(3, addr, len, hash);
+
+	for (i = 0; i < 16; i++)
+		pos[i] ^= hash[i];
+
+	/* derive plaintext length from first subfield */
+	*keylen = (unsigned char) str[0];
+	if ((u8*) (str + *keylen) >= (u8*) (buf + buflen)) {
+		// decryption error - invalid key length
+		return NULL;
+	}
+	if (*keylen == 0) {
+		// empty password
+		return NULL;
+	}
+
+	/* copy passphrase into new buffer */
+	char* ret = os_zalloc(*keylen);
+	os_memcpy(ret, str + 1, *keylen);
+
+	/* return new buffer */
+	return ret;
+}
+
+
 void radius_free_class(struct radius_class_data *c)
 {
 	size_t i;
diff --git a/src/radius/radius.h b/src/radius/radius.h
index a3cdac0..464eb1d 100644
--- a/src/radius/radius.h
+++ b/src/radius/radius.h
@@ -15,6 +15,8 @@ 
 #ifndef RADIUS_H
 #define RADIUS_H
 
+struct hostapd_ssid;
+
 /* RFC 2865 - RADIUS */
 
 #ifdef _MSC_VER
@@ -52,6 +54,7 @@  enum { RADIUS_ATTR_USER_NAME = 1,
        RADIUS_ATTR_USER_PASSWORD = 2,
        RADIUS_ATTR_NAS_IP_ADDRESS = 4,
        RADIUS_ATTR_NAS_PORT = 5,
+       RADIUS_ATTR_SERVICE_TYPE = 6,
        RADIUS_ATTR_FRAMED_MTU = 12,
        RADIUS_ATTR_REPLY_MESSAGE = 18,
        RADIUS_ATTR_STATE = 24,
@@ -82,6 +85,7 @@  enum { RADIUS_ATTR_USER_NAME = 1,
        RADIUS_ATTR_NAS_PORT_TYPE = 61,
        RADIUS_ATTR_TUNNEL_TYPE = 64,
        RADIUS_ATTR_TUNNEL_MEDIUM_TYPE = 65,
+       RADIUS_ATTR_TUNNEL_PASSWORD = 69,
        RADIUS_ATTR_CONNECT_INFO = 77,
        RADIUS_ATTR_EAP_MESSAGE = 79,
        RADIUS_ATTR_MESSAGE_AUTHENTICATOR = 80,
@@ -145,6 +149,19 @@  enum { RADIUS_ATTR_USER_NAME = 1,
 #define RADIUS_TUNNEL_MEDIUM_TYPE_IPV6 2
 #define RADIUS_TUNNEL_MEDIUM_TYPE_802 6
 
+/* Service-Type */
+#define RADIUS_SERVICE_TYPE_LOGIN 1
+#define RADIUS_SERVICE_TYPE_FRAMED 2
+#define RADIUS_SERVICE_TYPE_CALLBACK_LOGIN 3
+#define RADIUS_SERVICE_TYPE_CALLBACK_FRAMED 4
+#define RADIUS_SERVICE_TYPE_OUTBOUND 5
+#define RADIUS_SERVICE_TYPE_ADMINISTRATIVE 6
+#define RADIUS_SERVICE_TYPE_NAS_PROMPT 7
+#define RADIUS_SERVICE_TYPE_AUTHENTICATE_ONLY 8
+#define RADIUS_SERVICE_TYPE_CALLBACK_NAS_PROMPT 9
+#define RADIUS_SERVICE_TYPE_CALL_CHECK 10
+#define RADIUS_SERVICE_TYPE_CALLBACK ADMINISTRATIVE 11
+
 
 struct radius_attr_vendor {
 	u8 vendor_type;
@@ -231,6 +248,7 @@  radius_msg_add_attr_user_password(struct radius_msg *msg,
 				  const u8 *secret, size_t secret_len);
 int radius_msg_get_attr(struct radius_msg *msg, u8 type, u8 *buf, size_t len);
 int radius_msg_get_vlanid(struct radius_msg *msg);
+char* radius_msg_get_tunnel_password(struct radius_msg *msg, int* keylen, const u8 *secret, size_t secret_len, struct radius_msg *sent_msg);
 
 static inline int radius_msg_add_attr_int32(struct radius_msg *msg, u8 type,
 					    u32 value)