Patchwork [RFC,PATCHv3] Use radius supplied PSK / Passphrase for WPA-PSK

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Submitter michael-dev@fami-braun.de
Date Nov. 30, 2011, 6:49 a.m.
Message ID <20111130064903.GA6892@dynamic.fami-braun.de>
Download mbox | patch
Permalink /patch/128425/
State Superseded
Headers show

Comments

michael-dev@fami-braun.de - Nov. 30, 2011, 6:49 a.m.
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.
I found RouterOS to have a feature like this (Miktronik-Wireless-PSK or so radius attribute) but no source and a hint on this mailing list
that it should not be difficult to implement.
Please find a patch against git head attached that compiles fine and is currently under testing.

To use this, one needs to enable the macaddr_acl = RADIUS setting and have wpa_psk_radius=1.
For Freeradius, one needs to add
 VENDOR          Hostapd        39014
 ATTRIBUTE       Hostapd-PSK          1    integer             Hostapd
 ATTRIBUTE       Hostapd-Passphrase          2    string             Hostapd
to the dictionary file and make sure that either Hostapd-Passphrase or Hostapd-PSK (the latter has higher priority) is in the radius reply.
The PSK should be supplied hex encoded, the passphrase is turned into a psk by hostapd.

Regards,
 M. Braun
--
Changes since v1:
 * sent wrong file, changes only apply to documentation part
Changes since v2:
 * use free enterprise number

Patch

commit 1a73664e17928a746d6995e029512672e0ea0c2e
Author: mbr <mbr@wlan-nfs.fem.tu-ilmenau.de>
Date:   Tue Nov 29 20:29:22 2011 +0100

    add PSK-from-RADIUS support
    
    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 107d37a..7fe10eb 100644
--- a/hostapd/config_file.c
+++ b/hostapd/config_file.c
@@ -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 7571f45..2b11e89 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=0
+
 # 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/hostapd/hostapd.wpa_psk_radius b/hostapd/hostapd.wpa_psk_radius
new file mode 100644
index 0000000..d2bc235
--- /dev/null
+++ b/hostapd/hostapd.wpa_psk_radius
@@ -0,0 +1,10 @@ 
+To fetch PSK from radius, set macaddr_acl to radius and wpa_psk_radius=1 in hostapd.conf
+Add the following definition to freeradius vendor list
+
+ VENDOR          Hostapd        39014
+ ATTRIBUTE       Hostapd-PSK          1    integer             Hostapd
+ ATTRIBUTE       Hostapd-Passphrase          2    string             Hostapd
+
+and add either a Hostapd-PSK or Hostapd-Passphrase to the radius reply (PSK overriders Passphrase).
+PSK is the hex encoded 64 character dump of the psk.
+
diff --git a/src/ap/ap_config.c b/src/ap/ap_config.c
index cfb6b2d..bba436a 100644
--- a/src/ap/ap_config.c
+++ b/src/ap/ap_config.c
@@ -57,6 +57,8 @@  void hostapd_config_defaults_bss(struct hostapd_bss_config *bss)
 	bss->broadcast_key_idx_max = 2;
 	bss->eap_reauth_period = 3600;
 
+	bss->wpa_psk_radius = 0;
+
 	bss->wpa_group_rekey = 600;
 	bss->wpa_gmk_rekey = 86400;
 	bss->wpa_key_mgmt = WPA_KEY_MGMT_PSK;
diff --git a/src/ap/ap_config.h b/src/ap/ap_config.h
index 32c8292..75b8cc9 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 35a47f1..9834a24 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 +377,7 @@  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 +414,12 @@  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) {
+		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..e32d103 100644
--- a/src/ap/ieee802_11_auth.c
+++ b/src/ap/ieee802_11_auth.c
@@ -40,6 +40,8 @@  struct hostapd_cached_radius_acl {
 	u32 session_timeout;
 	u32 acct_interim_interval;
 	int vlan_id;
+        int with_psk;
+        u8 psk[PMK_LEN];
 };
 
 
@@ -68,7 +70,7 @@  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, int* with_psk, u8* psk[], int* has_psk)
 {
 	struct hostapd_cached_radius_acl *entry;
 	struct os_time now;
@@ -89,6 +91,10 @@  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;
 		}
 
@@ -214,7 +220,7 @@  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 +228,10 @@  int hostapd_allowed_address(struct hostapd_data *hapd, const u8 *addr,
 		*acct_interim_interval = 0;
 	if (vlan_id)
 		*vlan_id = 0;
+        if (has_psk)
+		*hash_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 +256,7 @@  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;
@@ -396,6 +406,7 @@  hostapd_acl_recv_radius(struct radius_msg *msg, struct radius_msg *req,
 			void *data)
 {
 	struct hostapd_data *hapd = data;
+        struct hostapd_ssid *ssid = &(hapd->conf->ssid);
 	struct hostapd_acl_query_data *query, *prev;
 	struct hostapd_cached_radius_acl *cache;
 	struct radius_hdr *hdr = radius_msg_get_hdr(msg);
@@ -456,6 +467,7 @@  hostapd_acl_recv_radius(struct radius_msg *msg, struct radius_msg *req,
 		}
 
 		cache->vlan_id = radius_msg_get_vlanid(msg);
+                cache->has_psk = radius_msg_get_psk(msg, cache->psk, ssid);
 	} 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..1c98f67 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/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..0a39fad 100644
--- a/src/radius/radius.c
+++ b/src/radius/radius.c
@@ -17,9 +17,10 @@ 
 #include "utils/common.h"
 #include "utils/wpabuf.h"
 #include "crypto/md5.h"
+#include "crypto/sha1.h"
 #include "crypto/crypto.h"
 #include "radius.h"
-
+#include "ap/ap_config.h"
 
 /**
  * struct radius_msg - RADIUS message structure for new and parsed messages
@@ -1275,6 +1276,40 @@  int radius_msg_get_vlanid(struct radius_msg *msg)
 }
 
 
+/**
+ * radius_msg_get_psk - Parse RADIUS attributes for PSK/Passphrase (WPA)
+ * @msg: RADIUS message
+ * @psk: buffer for PSK (len: PMK_LEN)
+ * Returns: 1 if psk found, 0 else
+ */
+int radius_msg_get_psk(struct radius_msg *msg, u8* psk, struct hostapd_ssid *ssid)
+{
+	char* key;
+        size_t keylen;
+
+        key = (char*) radius_msg_get_vendor_attr( msg, RADIUS_VENDOR_ID_HOSTAPD, RADIUS_VENDOR_ATTR_HAP_PSK, &keylen );
+        if (key) {
+		// PSK found, expect hex encoding
+                int len = os_strlen(key);
+                if (len == 64 && hexstr2bin(key, psk, PMK_LEN) == 0) {
+		  os_free(key); key=NULL;
+                  return 1;
+                }
+		// PSK had wrong length...
+		os_free(key); key=NULL;
+	}
+
+        key = (char*) radius_msg_get_vendor_attr(msg, RADIUS_VENDOR_ID_HOSTAPD, RADIUS_VENDOR_ATTR_HAP_PASSPHRASE, &keylen );
+        if (key) {
+		// Passphrase found
+		pbkdf2_sha1(key, ssid->ssid, ssid->ssid_len, 4096, psk, PMK_LEN);
+		os_free(key); key=NULL;
+		return 1;
+	} 
+	return 0;
+}
+
+
 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..a0dee46 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
@@ -172,6 +174,11 @@  struct radius_ms_mppe_keys {
 	size_t recv_len;
 };
 
+/* hostapd specific RADIUS Attributes */
+#define RADIUS_VENDOR_ID_HOSTAPD 39014
+enum {  RADIUS_VENDOR_ATTR_HAP_PSK = 1,
+        RADIUS_VENDOR_ATTR_HAP_PASSPHRASE = 2
+};
 
 struct radius_msg;
 
@@ -231,6 +238,7 @@  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);
+int radius_msg_get_psk(struct radius_msg *msg, u8* psk, struct hostapd_ssid *ssid);
 
 static inline int radius_msg_add_attr_int32(struct radius_msg *msg, u8 type,
 					    u32 value)