1 files changed, 223 insertions, 79 deletions

diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c
index 505d62247268..16da946f5881 100644
--- a/net/bluetooth/iso.c
+++ b/net/bluetooth/iso.c
@@ -48,6 +48,12 @@ static void iso_sock_kill(struct sock *sk);
 #define EIR_SERVICE_DATA_LENGTH 4
 #define BASE_MAX_LENGTH (HCI_MAX_PER_AD_LENGTH - EIR_SERVICE_DATA_LENGTH)
 
+/* iso_pinfo flags values */
+enum {
+	BT_SK_BIG_SYNC,
+	BT_SK_PA_SYNC,
+};
+
 struct iso_pinfo {
 	struct bt_sock		bt;
 	bdaddr_t		src;
@@ -58,7 +64,7 @@ struct iso_pinfo {
 	__u8			bc_num_bis;
 	__u8			bc_bis[ISO_MAX_NUM_BIS];
 	__u16			sync_handle;
-	__u32			flags;
+	unsigned long		flags;
 	struct bt_iso_qos	qos;
 	bool			qos_user_set;
 	__u8			base_len;
@@ -70,6 +76,8 @@ static struct bt_iso_qos default_qos;
 
 static bool check_ucast_qos(struct bt_iso_qos *qos);
 static bool check_bcast_qos(struct bt_iso_qos *qos);
+static bool iso_match_sid(struct sock *sk, void *data);
+static void iso_sock_disconn(struct sock *sk);
 
 /* ---- ISO timers ---- */
 #define ISO_CONN_TIMEOUT	(HZ * 40)
@@ -287,13 +295,24 @@ static int iso_connect_bis(struct sock *sk)
 		goto unlock;
 	}
 
-	hcon = hci_connect_bis(hdev, &iso_pi(sk)->dst,
-			       le_addr_type(iso_pi(sk)->dst_type),
-			       &iso_pi(sk)->qos, iso_pi(sk)->base_len,
-			       iso_pi(sk)->base);
-	if (IS_ERR(hcon)) {
-		err = PTR_ERR(hcon);
-		goto unlock;
+	/* Just bind if DEFER_SETUP has been set */
+	if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags)) {
+		hcon = hci_bind_bis(hdev, &iso_pi(sk)->dst,
+				    &iso_pi(sk)->qos, iso_pi(sk)->base_len,
+				    iso_pi(sk)->base);
+		if (IS_ERR(hcon)) {
+			err = PTR_ERR(hcon);
+			goto unlock;
+		}
+	} else {
+		hcon = hci_connect_bis(hdev, &iso_pi(sk)->dst,
+				       le_addr_type(iso_pi(sk)->dst_type),
+				       &iso_pi(sk)->qos, iso_pi(sk)->base_len,
+				       iso_pi(sk)->base);
+		if (IS_ERR(hcon)) {
+			err = PTR_ERR(hcon);
+			goto unlock;
+		}
 	}
 
 	conn = iso_conn_add(hcon);
@@ -317,6 +336,9 @@ static int iso_connect_bis(struct sock *sk)
 	if (hcon->state == BT_CONNECTED) {
 		iso_sock_clear_timer(sk);
 		sk->sk_state = BT_CONNECTED;
+	} else if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags)) {
+		iso_sock_clear_timer(sk);
+		sk->sk_state = BT_CONNECT;
 	} else {
 		sk->sk_state = BT_CONNECT;
 		iso_sock_set_timer(sk, sk->sk_sndtimeo);
@@ -579,6 +601,15 @@ static void iso_sock_cleanup_listen(struct sock *parent)
 		iso_sock_kill(sk);
 	}
 
+	/* If listening socket stands for a PA sync connection,
+	 * properly disconnect the hcon and socket.
+	 */
+	if (iso_pi(parent)->conn && iso_pi(parent)->conn->hcon &&
+	    test_bit(HCI_CONN_PA_SYNC, &iso_pi(parent)->conn->hcon->flags)) {
+		iso_sock_disconn(parent);
+		return;
+	}
+
 	parent->sk_state  = BT_CLOSED;
 	sock_set_flag(parent, SOCK_ZAPPED);
 }
@@ -600,16 +631,14 @@ static void iso_sock_kill(struct sock *sk)
 	sock_put(sk);
 }
 
-static void iso_conn_defer_reject(struct hci_conn *conn)
+static void iso_sock_disconn(struct sock *sk)
 {
-	struct hci_cp_le_reject_cis cp;
-
-	BT_DBG("conn %p", conn);
-
-	memset(&cp, 0, sizeof(cp));
-	cp.handle = cpu_to_le16(conn->handle);
-	cp.reason = HCI_ERROR_REJ_BAD_ADDR;
-	hci_send_cmd(conn->hdev, HCI_OP_LE_REJECT_CIS, sizeof(cp), &cp);
+	sk->sk_state = BT_DISCONN;
+	iso_sock_set_timer(sk, ISO_DISCONN_TIMEOUT);
+	iso_conn_lock(iso_pi(sk)->conn);
+	hci_conn_drop(iso_pi(sk)->conn->hcon);
+	iso_pi(sk)->conn->hcon = NULL;
+	iso_conn_unlock(iso_pi(sk)->conn);
 }
 
 static void __iso_sock_close(struct sock *sk)
@@ -621,37 +650,22 @@ static void __iso_sock_close(struct sock *sk)
 		iso_sock_cleanup_listen(sk);
 		break;
 
+	case BT_CONNECT:
 	case BT_CONNECTED:
 	case BT_CONFIG:
-		if (iso_pi(sk)->conn->hcon) {
-			sk->sk_state = BT_DISCONN;
-			iso_sock_set_timer(sk, ISO_DISCONN_TIMEOUT);
-			iso_conn_lock(iso_pi(sk)->conn);
-			hci_conn_drop(iso_pi(sk)->conn->hcon);
-			iso_pi(sk)->conn->hcon = NULL;
-			iso_conn_unlock(iso_pi(sk)->conn);
-		} else {
+		if (iso_pi(sk)->conn->hcon)
+			iso_sock_disconn(sk);
+		else
 			iso_chan_del(sk, ECONNRESET);
-		}
 		break;
 
 	case BT_CONNECT2:
-		if (iso_pi(sk)->conn->hcon)
-			iso_conn_defer_reject(iso_pi(sk)->conn->hcon);
-		iso_chan_del(sk, ECONNRESET);
-		break;
-	case BT_CONNECT:
-		/* In case of DEFER_SETUP the hcon would be bound to CIG which
-		 * needs to be removed so just call hci_conn_del so the cleanup
-		 * callback do what is needed.
-		 */
-		if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags) &&
-		    iso_pi(sk)->conn->hcon) {
-			hci_conn_del(iso_pi(sk)->conn->hcon);
-			iso_pi(sk)->conn->hcon = NULL;
-		}
-
-		iso_chan_del(sk, ECONNRESET);
+		if (iso_pi(sk)->conn->hcon &&
+		    (test_bit(HCI_CONN_PA_SYNC, &iso_pi(sk)->conn->hcon->flags) ||
+		    test_bit(HCI_CONN_PA_SYNC_FAILED, &iso_pi(sk)->conn->hcon->flags)))
+			iso_sock_disconn(sk);
+		else
+			iso_chan_del(sk, ECONNRESET);
 		break;
 	case BT_DISCONN:
 		iso_chan_del(sk, ECONNRESET);
@@ -724,21 +738,13 @@ static struct sock *iso_sock_alloc(struct net *net, struct socket *sock,
 {
 	struct sock *sk;
 
-	sk = sk_alloc(net, PF_BLUETOOTH, prio, &iso_proto, kern);
+	sk = bt_sock_alloc(net, sock, &iso_proto, proto, prio, kern);
 	if (!sk)
 		return NULL;
 
-	sock_init_data(sock, sk);
-	INIT_LIST_HEAD(&bt_sk(sk)->accept_q);
-
 	sk->sk_destruct = iso_sock_destruct;
 	sk->sk_sndtimeo = ISO_CONN_TIMEOUT;
 
-	sock_reset_flag(sk, SOCK_ZAPPED);
-
-	sk->sk_protocol = proto;
-	sk->sk_state    = BT_OPEN;
-
 	/* Set address type as public as default src address is BDADDR_ANY */
 	iso_pi(sk)->src_type = BDADDR_LE_PUBLIC;
 
@@ -1154,6 +1160,29 @@ static void iso_conn_defer_accept(struct hci_conn *conn)
 	hci_send_cmd(hdev, HCI_OP_LE_ACCEPT_CIS, sizeof(cp), &cp);
 }
 
+static void iso_conn_big_sync(struct sock *sk)
+{
+	int err;
+	struct hci_dev *hdev;
+
+	hdev = hci_get_route(&iso_pi(sk)->dst, &iso_pi(sk)->src,
+			     iso_pi(sk)->src_type);
+
+	if (!hdev)
+		return;
+
+	if (!test_and_set_bit(BT_SK_BIG_SYNC, &iso_pi(sk)->flags)) {
+		err = hci_le_big_create_sync(hdev, iso_pi(sk)->conn->hcon,
+					     &iso_pi(sk)->qos,
+					     iso_pi(sk)->sync_handle,
+					     iso_pi(sk)->bc_num_bis,
+					     iso_pi(sk)->bc_bis);
+		if (err)
+			bt_dev_err(hdev, "hci_le_big_create_sync: %d",
+				   err);
+	}
+}
+
 static int iso_sock_recvmsg(struct socket *sock, struct msghdr *msg,
 			    size_t len, int flags)
 {
@@ -1166,8 +1195,15 @@ static int iso_sock_recvmsg(struct socket *sock, struct msghdr *msg,
 		lock_sock(sk);
 		switch (sk->sk_state) {
 		case BT_CONNECT2:
-			iso_conn_defer_accept(pi->conn->hcon);
-			sk->sk_state = BT_CONFIG;
+			if (pi->conn->hcon &&
+			    test_bit(HCI_CONN_PA_SYNC, &pi->conn->hcon->flags)) {
+				iso_conn_big_sync(sk);
+				sk->sk_state = BT_LISTEN;
+				set_bit(BT_SK_PA_SYNC, &iso_pi(sk)->flags);
+			} else {
+				iso_conn_defer_accept(pi->conn->hcon);
+				sk->sk_state = BT_CONFIG;
+			}
 			release_sock(sk);
 			return 0;
 		case BT_CONNECT:
@@ -1202,6 +1238,12 @@ static bool check_io_qos(struct bt_iso_io_qos *qos)
 
 static bool check_ucast_qos(struct bt_iso_qos *qos)
 {
+	if (qos->ucast.cig > 0xef && qos->ucast.cig != BT_ISO_QOS_CIG_UNSET)
+		return false;
+
+	if (qos->ucast.cis > 0xef && qos->ucast.cis != BT_ISO_QOS_CIS_UNSET)
+		return false;
+
 	if (qos->ucast.sca > 0x07)
 		return false;
 
@@ -1291,6 +1333,18 @@ static int iso_sock_setsockopt(struct socket *sock, int level, int optname,
 			clear_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags);
 		break;
 
+	case BT_PKT_STATUS:
+		if (copy_from_sockptr(&opt, optval, sizeof(u32))) {
+			err = -EFAULT;
+			break;
+		}
+
+		if (opt)
+			set_bit(BT_SK_PKT_STATUS, &bt_sk(sk)->flags);
+		else
+			clear_bit(BT_SK_PKT_STATUS, &bt_sk(sk)->flags);
+		break;
+
 	case BT_ISO_QOS:
 		if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND &&
 		    sk->sk_state != BT_CONNECT2) {
@@ -1376,6 +1430,12 @@ static int iso_sock_getsockopt(struct socket *sock, int level, int optname,
 
 		break;
 
+	case BT_PKT_STATUS:
+		if (put_user(test_bit(BT_SK_PKT_STATUS, &bt_sk(sk)->flags),
+			     (int __user *)optval))
+			err = -EFAULT;
+		break;
+
 	case BT_ISO_QOS:
 		qos = iso_sock_get_qos(sk);
 
@@ -1386,7 +1446,8 @@ static int iso_sock_getsockopt(struct socket *sock, int level, int optname,
 		break;
 
 	case BT_ISO_BASE:
-		if (sk->sk_state == BT_CONNECTED) {
+		if (sk->sk_state == BT_CONNECTED &&
+		    !bacmp(&iso_pi(sk)->dst, BDADDR_ANY)) {
 			base_len = iso_pi(sk)->conn->hcon->le_per_adv_data_len;
 			base = iso_pi(sk)->conn->hcon->le_per_adv_data;
 		} else {
@@ -1466,7 +1527,7 @@ static int iso_sock_release(struct socket *sock)
 
 	iso_sock_close(sk);
 
-	if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime &&
+	if (sock_flag(sk, SOCK_LINGER) && READ_ONCE(sk->sk_lingertime) &&
 	    !(current->flags & PF_EXITING)) {
 		lock_sock(sk);
 		err = bt_sock_wait_state(sk, BT_CLOSED, sk->sk_lingertime);
@@ -1504,11 +1565,17 @@ static bool iso_match_big(struct sock *sk, void *data)
 	return ev->handle == iso_pi(sk)->qos.bcast.big;
 }
 
+static bool iso_match_pa_sync_flag(struct sock *sk, void *data)
+{
+	return test_bit(BT_SK_PA_SYNC, &iso_pi(sk)->flags);
+}
+
 static void iso_conn_ready(struct iso_conn *conn)
 {
-	struct sock *parent;
+	struct sock *parent = NULL;
 	struct sock *sk = conn->sk;
-	struct hci_ev_le_big_sync_estabilished *ev;
+	struct hci_ev_le_big_sync_estabilished *ev = NULL;
+	struct hci_ev_le_pa_sync_established *ev2 = NULL;
 	struct hci_conn *hcon;
 
 	BT_DBG("conn %p", conn);
@@ -1520,15 +1587,32 @@ static void iso_conn_ready(struct iso_conn *conn)
 		if (!hcon)
 			return;
 
-		ev = hci_recv_event_data(hcon->hdev,
-					 HCI_EVT_LE_BIG_SYNC_ESTABILISHED);
-		if (ev)
+		if (test_bit(HCI_CONN_BIG_SYNC, &hcon->flags) ||
+		    test_bit(HCI_CONN_BIG_SYNC_FAILED, &hcon->flags)) {
+			ev = hci_recv_event_data(hcon->hdev,
+						 HCI_EVT_LE_BIG_SYNC_ESTABILISHED);
+
+			/* Get reference to PA sync parent socket, if it exists */
 			parent = iso_get_sock_listen(&hcon->src,
 						     &hcon->dst,
-						     iso_match_big, ev);
-		else
+						     iso_match_pa_sync_flag, NULL);
+			if (!parent && ev)
+				parent = iso_get_sock_listen(&hcon->src,
+							     &hcon->dst,
+							     iso_match_big, ev);
+		} else if (test_bit(HCI_CONN_PA_SYNC, &hcon->flags) ||
+				test_bit(HCI_CONN_PA_SYNC_FAILED, &hcon->flags)) {
+			ev2 = hci_recv_event_data(hcon->hdev,
+						  HCI_EV_LE_PA_SYNC_ESTABLISHED);
+			if (ev2)
+				parent = iso_get_sock_listen(&hcon->src,
+							     &hcon->dst,
+							     iso_match_sid, ev2);
+		}
+
+		if (!parent)
 			parent = iso_get_sock_listen(&hcon->src,
-						     BDADDR_ANY, NULL, NULL);
+							BDADDR_ANY, NULL, NULL);
 
 		if (!parent)
 			return;
@@ -1545,11 +1629,17 @@ static void iso_conn_ready(struct iso_conn *conn)
 		iso_sock_init(sk, parent);
 
 		bacpy(&iso_pi(sk)->src, &hcon->src);
-		iso_pi(sk)->src_type = hcon->src_type;
+
+		/* Convert from HCI to three-value type */
+		if (hcon->src_type == ADDR_LE_DEV_PUBLIC)
+			iso_pi(sk)->src_type = BDADDR_LE_PUBLIC;
+		else
+			iso_pi(sk)->src_type = BDADDR_LE_RANDOM;
 
 		/* If hcon has no destination address (BDADDR_ANY) it means it
-		 * was created by HCI_EV_LE_BIG_SYNC_ESTABILISHED so we need to
-		 * initialize using the parent socket destination address.
+		 * was created by HCI_EV_LE_BIG_SYNC_ESTABILISHED or
+		 * HCI_EV_LE_PA_SYNC_ESTABLISHED so we need to initialize using
+		 * the parent socket destination address.
 		 */
 		if (!bacmp(&hcon->dst, BDADDR_ANY)) {
 			bacpy(&hcon->dst, &iso_pi(parent)->dst);
@@ -1557,12 +1647,29 @@ static void iso_conn_ready(struct iso_conn *conn)
 			hcon->sync_handle = iso_pi(parent)->sync_handle;
 		}
 
+		if (ev2 && !ev2->status) {
+			iso_pi(sk)->sync_handle = iso_pi(parent)->sync_handle;
+			iso_pi(sk)->qos = iso_pi(parent)->qos;
+			iso_pi(sk)->bc_num_bis = iso_pi(parent)->bc_num_bis;
+			memcpy(iso_pi(sk)->bc_bis, iso_pi(parent)->bc_bis, ISO_MAX_NUM_BIS);
+		}
+
 		bacpy(&iso_pi(sk)->dst, &hcon->dst);
 		iso_pi(sk)->dst_type = hcon->dst_type;
+		iso_pi(sk)->sync_handle = iso_pi(parent)->sync_handle;
+		memcpy(iso_pi(sk)->base, iso_pi(parent)->base, iso_pi(parent)->base_len);
+		iso_pi(sk)->base_len = iso_pi(parent)->base_len;
 
 		hci_conn_hold(hcon);
 		iso_chan_add(conn, sk, parent);
 
+		if ((ev && ((struct hci_evt_le_big_sync_estabilished *)ev)->status) ||
+		    (ev2 && ev2->status)) {
+			/* Trigger error signal on child socket */
+			sk->sk_err = ECONNREFUSED;
+			sk->sk_error_report(sk);
+		}
+
 		if (test_bit(BT_SK_DEFER_SETUP, &bt_sk(parent)->flags))
 			sk->sk_state = BT_CONNECT2;
 		else
@@ -1589,12 +1696,20 @@ static bool iso_match_sync_handle(struct sock *sk, void *data)
 	return le16_to_cpu(ev->sync_handle) == iso_pi(sk)->sync_handle;
 }
 
+static bool iso_match_sync_handle_pa_report(struct sock *sk, void *data)
+{
+	struct hci_ev_le_per_adv_report *ev = data;
+
+	return le16_to_cpu(ev->sync_handle) == iso_pi(sk)->sync_handle;
+}
+
 /* ----- ISO interface with lower layer (HCI) ----- */
 
 int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
 {
 	struct hci_ev_le_pa_sync_established *ev1;
 	struct hci_evt_le_big_info_adv_report *ev2;
+	struct hci_ev_le_per_adv_report *ev3;
 	struct sock *sk;
 	int lm = 0;
 
@@ -1610,12 +1725,15 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
 	 * 2. HCI_EVT_LE_BIG_INFO_ADV_REPORT: When connect_ind is triggered by a
 	 * a BIG Info it attempts to check if there any listening socket with
 	 * the same sync_handle and if it does then attempt to create a sync.
+	 * 3. HCI_EV_LE_PER_ADV_REPORT: When a PA report is received, it is stored
+	 * in iso_pi(sk)->base so it can be passed up to user, in the case of a
+	 * broadcast sink.
 	 */
 	ev1 = hci_recv_event_data(hdev, HCI_EV_LE_PA_SYNC_ESTABLISHED);
 	if (ev1) {
 		sk = iso_get_sock_listen(&hdev->bdaddr, bdaddr, iso_match_sid,
 					 ev1);
-		if (sk)
+		if (sk && !ev1->status)
 			iso_pi(sk)->sync_handle = le16_to_cpu(ev1->handle);
 
 		goto done;
@@ -1623,25 +1741,43 @@ int iso_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr, __u8 *flags)
 
 	ev2 = hci_recv_event_data(hdev, HCI_EVT_LE_BIG_INFO_ADV_REPORT);
 	if (ev2) {
+		/* Try to get PA sync listening socket, if it exists */
 		sk = iso_get_sock_listen(&hdev->bdaddr, bdaddr,
-					 iso_match_sync_handle, ev2);
+						iso_match_pa_sync_flag, NULL);
+		if (!sk)
+			sk = iso_get_sock_listen(&hdev->bdaddr, bdaddr,
+						 iso_match_sync_handle, ev2);
 		if (sk) {
 			int err;
 
 			if (ev2->num_bis < iso_pi(sk)->bc_num_bis)
 				iso_pi(sk)->bc_num_bis = ev2->num_bis;
 
-			err = hci_le_big_create_sync(hdev,
-						     &iso_pi(sk)->qos,
-						     iso_pi(sk)->sync_handle,
-						     iso_pi(sk)->bc_num_bis,
-						     iso_pi(sk)->bc_bis);
-			if (err) {
-				bt_dev_err(hdev, "hci_le_big_create_sync: %d",
-					   err);
-				sk = NULL;
+			if (!test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags) &&
+			    !test_and_set_bit(BT_SK_BIG_SYNC, &iso_pi(sk)->flags)) {
+				err = hci_le_big_create_sync(hdev, NULL,
+							     &iso_pi(sk)->qos,
+							     iso_pi(sk)->sync_handle,
+							     iso_pi(sk)->bc_num_bis,
+							     iso_pi(sk)->bc_bis);
+				if (err) {
+					bt_dev_err(hdev, "hci_le_big_create_sync: %d",
+						   err);
+					sk = NULL;
+				}
 			}
 		}
+	}
+
+	ev3 = hci_recv_event_data(hdev, HCI_EV_LE_PER_ADV_REPORT);
+	if (ev3) {
+		sk = iso_get_sock_listen(&hdev->bdaddr, bdaddr,
+					 iso_match_sync_handle_pa_report, ev3);
+
+		if (sk) {
+			memcpy(iso_pi(sk)->base, ev3->data, ev3->length);
+			iso_pi(sk)->base_len = ev3->length;
+		}
 	} else {
 		sk = iso_get_sock_listen(&hdev->bdaddr, BDADDR_ANY, NULL, NULL);
 	}
@@ -1676,13 +1812,19 @@ static void iso_connect_cfm(struct hci_conn *hcon, __u8 status)
 		}
 
 		/* Create CIS if pending */
-		hci_le_create_cis(hcon);
+		hci_le_create_cis_pending(hcon->hdev);
 		return;
 	}
 
 	BT_DBG("hcon %p bdaddr %pMR status %d", hcon, &hcon->dst, status);
 
-	if (!status) {
+	/* Similar to the success case, if HCI_CONN_BIG_SYNC_FAILED or
+	 * HCI_CONN_PA_SYNC_FAILED is set, queue the failed connection
+	 * into the accept queue of the listening socket and wake up
+	 * userspace, to inform the user about the event.
+	 */
+	if (!status || test_bit(HCI_CONN_BIG_SYNC_FAILED, &hcon->flags) ||
+	    test_bit(HCI_CONN_PA_SYNC_FAILED, &hcon->flags)) {
 		struct iso_conn *conn;
 
 		conn = iso_conn_add(hcon);
@@ -1757,6 +1899,7 @@ void iso_recv(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
 
 		if (len == skb->len) {
 			/* Complete frame received */
+			hci_skb_pkt_status(skb) = flags & 0x03;
 			iso_recv_frame(conn, skb);
 			return;
 		}
@@ -1778,6 +1921,7 @@ void iso_recv(struct hci_conn *hcon, struct sk_buff *skb, u16 flags)
 		if (!conn->rx_skb)
 			goto drop;
 
+		hci_skb_pkt_status(conn->rx_skb) = flags & 0x03;
 		skb_copy_from_linear_data(skb, skb_put(conn->rx_skb, skb->len),
 					  skb->len);
 		conn->rx_len = len - skb->len;