Bluetooth: Add CID field to L2CAP socket address structure

In preparation for L2CAP fixed channel support, the CID value of a
L2CAP connection needs to be accessible via the socket interface. The
CID is the connection identifier and exists as source and destination
value. So extend the L2CAP socket address structure with this field and
change getsockname() and getpeername() to fill it in.

The bind() and connect() functions have been modified to handle L2CAP
socket address structures of variable sizes. This makes them future
proof if additional fields need to be added.
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

include/net/bluetooth/l2cap.h

@@ -37,6 +37,7 @@ struct sockaddr_l2 {
 	sa_family_t	l2_family;
 	__le16		l2_psm;
 	bdaddr_t	l2_bdaddr;
+	__le16		l2_cid;
 };
 
 /* L2CAP socket options */

net/bluetooth/l2cap.c

@@ -770,17 +770,21 @@ static int l2cap_sock_create(struct net *net, struct socket *sock, int protocol)
 	return 0;
 }
 
-static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
+static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 {
-	struct sockaddr_l2 *la = (struct sockaddr_l2 *) addr;
 	struct sock *sk = sock->sk;
-	int err = 0;
+	struct sockaddr_l2 la;
+	int len, err = 0;
 
-	BT_DBG("sk %p, %s %d", sk, batostr(&la->l2_bdaddr), la->l2_psm);
+	BT_DBG("sk %p", sk);
 
 	if (!addr || addr->sa_family != AF_BLUETOOTH)
 		return -EINVAL;
 
+	memset(&la, 0, sizeof(la));
+	len = min_t(unsigned int, sizeof(la), alen);
+	memcpy(&la, addr, len);
+
 	lock_sock(sk);
 
 	if (sk->sk_state != BT_OPEN) {
@@ -788,7 +792,7 @@ static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int addr_
 		goto done;
 	}
 
-	if (la->l2_psm && btohs(la->l2_psm) < 0x1001 &&
+	if (la.l2_psm && btohs(la.l2_psm) < 0x1001 &&
 				!capable(CAP_NET_BIND_SERVICE)) {
 		err = -EACCES;
 		goto done;
@@ -796,16 +800,16 @@ static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int addr_
 
 	write_lock_bh(&l2cap_sk_list.lock);
 
-	if (la->l2_psm && __l2cap_get_sock_by_addr(la->l2_psm, &la->l2_bdaddr)) {
+	if (la.l2_psm && __l2cap_get_sock_by_addr(la.l2_psm, &la.l2_bdaddr)) {
 		err = -EADDRINUSE;
 	} else {
 		/* Save source address */
-		bacpy(&bt_sk(sk)->src, &la->l2_bdaddr);
-		l2cap_pi(sk)->psm   = la->l2_psm;
-		l2cap_pi(sk)->sport = la->l2_psm;
+		bacpy(&bt_sk(sk)->src, &la.l2_bdaddr);
+		l2cap_pi(sk)->psm   = la.l2_psm;
+		l2cap_pi(sk)->sport = la.l2_psm;
 		sk->sk_state = BT_BOUND;
 
-		if (btohs(la->l2_psm) == 0x0001 || btohs(la->l2_psm) == 0x0003)
+		if (btohs(la.l2_psm) == 0x0001 || btohs(la.l2_psm) == 0x0003)
 			l2cap_pi(sk)->sec_level = BT_SECURITY_SDP;
 	}
 
@@ -826,7 +830,8 @@ static int l2cap_do_connect(struct sock *sk)
 	__u8 auth_type;
 	int err = 0;
 
-	BT_DBG("%s -> %s psm 0x%2.2x", batostr(src), batostr(dst), l2cap_pi(sk)->psm);
+	BT_DBG("%s -> %s psm 0x%2.2x", batostr(src), batostr(dst),
+							l2cap_pi(sk)->psm);
 
 	if (!(hdev = hci_get_route(dst, src)))
 		return -EHOSTUNREACH;
@@ -906,20 +911,24 @@ static int l2cap_do_connect(struct sock *sk)
 
 static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr, int alen, int flags)
 {
-	struct sockaddr_l2 *la = (struct sockaddr_l2 *) addr;
 	struct sock *sk = sock->sk;
-	int err = 0;
+	struct sockaddr_l2 la;
+	int len, err = 0;
 
 	lock_sock(sk);
 
 	BT_DBG("sk %p", sk);
 
-	if (addr->sa_family != AF_BLUETOOTH || alen < sizeof(struct sockaddr_l2)) {
+	if (!addr || addr->sa_family != AF_BLUETOOTH) {
 		err = -EINVAL;
 		goto done;
 	}
 
-	if (sk->sk_type == SOCK_SEQPACKET && !la->l2_psm) {
+	memset(&la, 0, sizeof(la));
+	len = min_t(unsigned int, sizeof(la), alen);
+	memcpy(&la, addr, len);
+
+	if (sk->sk_type == SOCK_SEQPACKET && !la.l2_psm) {
 		err = -EINVAL;
 		goto done;
 	}
@@ -946,8 +955,8 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr, int al
 	}
 
 	/* Set destination address and psm */
-	bacpy(&bt_sk(sk)->dst, &la->l2_bdaddr);
-	l2cap_pi(sk)->psm = la->l2_psm;
+	bacpy(&bt_sk(sk)->dst, &la.l2_bdaddr);
+	l2cap_pi(sk)->psm = la.l2_psm;
 
 	if ((err = l2cap_do_connect(sk)))
 		goto done;
@@ -1071,12 +1080,16 @@ static int l2cap_sock_getname(struct socket *sock, struct sockaddr *addr, int *l
 	addr->sa_family = AF_BLUETOOTH;
 	*len = sizeof(struct sockaddr_l2);
 
-	if (peer)
+	if (peer) {
+		la->l2_psm = l2cap_pi(sk)->psm;
 		bacpy(&la->l2_bdaddr, &bt_sk(sk)->dst);
-	else
+		la->l2_cid = htobs(l2cap_pi(sk)->dcid);
+	} else {
+		la->l2_psm = l2cap_pi(sk)->sport;
 		bacpy(&la->l2_bdaddr, &bt_sk(sk)->src);
+		la->l2_cid = htobs(l2cap_pi(sk)->scid);
+	}
 
-	la->l2_psm = l2cap_pi(sk)->psm;
 	return 0;
 }
 
@@ -1208,7 +1221,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
 {
 	struct sock *sk = sock->sk;
 	struct l2cap_options opts;
-	int err = 0, len;
+	int len, err = 0;
 	u32 opt;
 
 	BT_DBG("sk %p", sk);