From: Shivani Baranwal <quic_shivbara@quicinc.com>
Date: Sun, 4 Aug 2024 21:13:59 +0000 (+0530)
Subject: P2P2: Parser function for PASN Encrypted Data element and DevIK
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3207ad1ca506326b8bbb60f590a028cd17e23030;p=thirdparty%2Fhostap.git

P2P2: Parser function for PASN Encrypted Data element and DevIK

Parse the encrypted P2P2 IE from PASN authentication frames and store a
copy of DevIK information so that this is available for use if the
connection succeeds for a persistent group.

Signed-off-by: Shivani Baranwal <quic_shivbara@quicinc.com>
---

diff --git a/src/p2p/p2p.c b/src/p2p/p2p.c
index e109e320c..0dde48b42 100644
--- a/src/p2p/p2p.c
+++ b/src/p2p/p2p.c
@@ -6419,6 +6419,90 @@ out:
 }
 
 
+int p2p_parse_data_element(struct p2p_data *p2p, const u8 *data, size_t len)
+{
+	u8 attr_id;
+	const u8 *pos, *next;
+	u16 rem_len, attr_len;
+
+	if (!p2p || !data || !len)
+		return -1;
+
+	pos = data;
+	rem_len = len;
+
+	if (rem_len < 6 ||
+	    pos[0] != WLAN_EID_VENDOR_SPECIFIC ||
+	    pos[1] < 4 ||
+	    rem_len < 2 + pos[1] ||
+	    WPA_GET_BE32(&pos[2]) != P2P2_IE_VENDOR_TYPE) {
+		p2p_dbg(p2p,
+			"P2P: P2P2 IE not present in PASN Encrypted Data element");
+		return -1;
+	}
+
+	pos += 6;
+	rem_len -= 6;
+
+	while (rem_len >= 3) {
+		attr_id = *pos++;
+		attr_len = WPA_GET_LE16(pos);
+		pos += 2;
+		rem_len -= 3;
+		if (rem_len < attr_len)
+			return -1;
+		next = pos + attr_len;
+		rem_len -= attr_len;
+
+		switch (attr_id) {
+		case P2P_ATTR_DEVICE_IDENTITY_KEY:
+			if (attr_len < 1) {
+				p2p_dbg(p2p,
+					"Too short Device Identity Key attribute");
+				return -1;
+			}
+			p2p->dik_cipher_version = *pos++;
+			attr_len--;
+			if (p2p->dik_cipher_version ==
+			    DIRA_CIPHER_VERSION_128) {
+				if (attr_len < DEVICE_IDENTITY_KEY_LEN) {
+					p2p_dbg(p2p, "Too short DevIK");
+					return -1;
+				}
+				os_memcpy(p2p->peer_dik_data, pos,
+					  DEVICE_IDENTITY_KEY_LEN);
+				p2p->peer_dik_len = DEVICE_IDENTITY_KEY_LEN;
+				pos += DEVICE_IDENTITY_KEY_LEN;
+				attr_len -= DEVICE_IDENTITY_KEY_LEN;
+			} else {
+				p2p_dbg(p2p,
+					"Unsupported cipher version %u in Device Identity Key attribute",
+					p2p->dik_cipher_version);
+				return -1;
+			}
+			if (attr_len < 4) {
+				p2p_dbg(p2p,
+					"Not enough room for DevIK lifetime");
+				return -1;
+			}
+			p2p->peer_dik_lifetime = WPA_GET_BE32(pos);
+			p2p_dbg(p2p,
+				"Received peer DevIK of length %zu octets and lifetime %u",
+				p2p->peer_dik_len, p2p->peer_dik_lifetime);
+			break;
+		default:
+			p2p_dbg(p2p,
+				"Unsupported Attribute ID %u in P2P2 IE in PASN Encrypted Data element",
+				attr_id);
+			break;
+		}
+		pos = next;
+	}
+
+	return 0;
+}
+
+
 int p2p_pasn_auth_tx_status(struct p2p_data *p2p, const u8 *data,
 			    size_t data_len, bool acked)
 {
@@ -6533,6 +6617,9 @@ static int p2p_handle_pasn_auth(struct p2p_data *p2p, struct p2p_device *dev,
 						   auth_transaction)) {
 			p2p_dbg(p2p,
 				"PASN Responder: Handle Auth 3 action wrapper failed");
+			/* Drop keying material from a failed pairing attempt */
+			os_memset(p2p->peer_dik_data, 0,
+				  sizeof(p2p->peer_dik_data));
 			return -1;
 		}
 		forced_memzero(pasn_get_ptk(pasn), sizeof(pasn->ptk));
diff --git a/src/p2p/p2p.h b/src/p2p/p2p.h
index 56b80d89e..ab93900e4 100644
--- a/src/p2p/p2p.h
+++ b/src/p2p/p2p.h
@@ -2580,6 +2580,7 @@ int p2p_initiate_pasn_auth(struct p2p_data *p2p, const u8 *addr, int freq);
 int p2p_pasn_auth_rx(struct p2p_data *p2p, const struct ieee80211_mgmt *mgmt,
 		     size_t len, int freq);
 int p2p_prepare_data_element(struct p2p_data *p2p, const u8 *peer_addr);
+int p2p_parse_data_element(struct p2p_data *p2p, const u8 *data, size_t len);
 int p2p_pasn_auth_tx_status(struct p2p_data *p2p, const u8 *data,
 			    size_t data_len, bool acked);
 
diff --git a/src/p2p/p2p_i.h b/src/p2p/p2p_i.h
index d7dfba825..571f4fc93 100644
--- a/src/p2p/p2p_i.h
+++ b/src/p2p/p2p_i.h
@@ -642,6 +642,19 @@ struct p2p_data {
 	struct rsn_pmksa_cache *initiator_pmksa;
 	/* Pairing responder PMKSA cache */
 	struct rsn_pmksa_cache *responder_pmksa;
+
+	/* DevIK variables: Cipher version, DevIK, and its lifetime
+	 * These are fetched from the P2P2 included in the PASN Encrypted Data
+	 * element during P2P2 group negotiation with PASN Authentication
+	 * frames. These values are stored in struct p2p_data for an ongoing GO
+	 * negotiation or join-a-group operation with the assumption that these
+	 * operations cannot happen in parallel with multiple peers. After
+	 * successful group formation and connection, these are moved to
+	 * wpa_supplicant configuration if the connection is persistent. */
+	u8 dik_cipher_version;
+	u8 peer_dik_data[DEVICE_IDENTITY_KEY_MAX_LEN];
+	size_t peer_dik_len;
+	unsigned int peer_dik_lifetime;
 };
 
 /**