Bluetooth: Add support for deferring L2CAP connection setup

In order to decide if listening L2CAP sockets should be accept()ed
the BD_ADDR of the remote device needs to be known. This patch adds
a socket option which defines a timeout for deferring the actual
connection setup.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 101 insertions, 9 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index df1a95e185c6..123efb46d3f5 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -372,9 +372,17 @@ static void l2cap_conn_start(struct l2cap_conn *conn)
                         rsp.dcid = cpu_to_le16(l2cap_pi(sk)->scid);
 
                         if (l2cap_check_link_mode(sk)) {
-                                sk->sk_state = BT_CONFIG;
-                                rsp.result = cpu_to_le16(L2CAP_CR_SUCCESS);
-                                rsp.status = cpu_to_le16(L2CAP_CS_NO_INFO);
+                                if (bt_sk(sk)->defer_setup) {
+                                        struct sock *parent = bt_sk(sk)->parent;
+                                        rsp.result = cpu_to_le16(L2CAP_CR_PEND);
+                                        rsp.status = cpu_to_le16(L2CAP_CS_AUTHOR_PEND);
+                                        parent->sk_data_ready(parent, 0);
+
+                                } else {
+                                        sk->sk_state = BT_CONFIG;
+                                        rsp.result = cpu_to_le16(L2CAP_CR_SUCCESS);
+                                        rsp.status = cpu_to_le16(L2CAP_CS_NO_INFO);
+                                }
                         } else {
                                 rsp.result = cpu_to_le16(L2CAP_CR_PEND);
                                 rsp.status = cpu_to_le16(L2CAP_CS_AUTHEN_PEND);
@@ -608,7 +616,6 @@ static void __l2cap_sock_close(struct sock *sk, int reason)
 
         case BT_CONNECTED:
         case BT_CONFIG:
-        case BT_CONNECT2:
                 if (sk->sk_type == SOCK_SEQPACKET) {
                         struct l2cap_conn *conn = l2cap_pi(sk)->conn;
                         struct l2cap_disconn_req req;
@@ -624,6 +631,27 @@ static void __l2cap_sock_close(struct sock *sk, int reason)
                         l2cap_chan_del(sk, reason);
                 break;
 
+        case BT_CONNECT2:
+                if (sk->sk_type == SOCK_SEQPACKET) {
+                        struct l2cap_conn *conn = l2cap_pi(sk)->conn;
+                        struct l2cap_conn_rsp rsp;
+                        __u16 result;
+
+                        if (bt_sk(sk)->defer_setup)
+                                result = L2CAP_CR_SEC_BLOCK;
+                        else
+                                result = L2CAP_CR_BAD_PSM;
+
+                        rsp.scid   = cpu_to_le16(l2cap_pi(sk)->dcid);
+                        rsp.dcid   = cpu_to_le16(l2cap_pi(sk)->scid);
+                        rsp.result = cpu_to_le16(result);
+                        rsp.status = cpu_to_le16(L2CAP_CS_NO_INFO);
+                        l2cap_send_cmd(conn, l2cap_pi(sk)->ident,
+                                        L2CAP_CONN_RSP, sizeof(rsp), &rsp);
+                } else
+                        l2cap_chan_del(sk, reason);
+                break;
+
         case BT_CONNECT:
         case BT_DISCONN:
                 l2cap_chan_del(sk, reason);
@@ -653,6 +681,8 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
 
         if (parent) {
                 sk->sk_type = parent->sk_type;
+                bt_sk(sk)->defer_setup = bt_sk(parent)->defer_setup;
+
                 pi->imtu = l2cap_pi(parent)->imtu;
                 pi->omtu = l2cap_pi(parent)->omtu;
                 pi->link_mode = l2cap_pi(parent)->link_mode;
@@ -1106,6 +1136,33 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
         return err;
 }
 
+static int l2cap_sock_recvmsg(struct kiocb *iocb, struct socket *sock, struct msghdr *msg, size_t len, int flags)
+{
+        struct sock *sk = sock->sk;
+
+        lock_sock(sk);
+
+        if (sk->sk_state == BT_CONNECT2 && bt_sk(sk)->defer_setup) {
+                struct l2cap_conn_rsp rsp;
+
+                sk->sk_state = BT_CONFIG;
+
+                rsp.scid   = cpu_to_le16(l2cap_pi(sk)->dcid);
+                rsp.dcid   = cpu_to_le16(l2cap_pi(sk)->scid);
+                rsp.result = cpu_to_le16(L2CAP_CR_SUCCESS);
+                rsp.status = cpu_to_le16(L2CAP_CS_NO_INFO);
+                l2cap_send_cmd(l2cap_pi(sk)->conn, l2cap_pi(sk)->ident,
+                                        L2CAP_CONN_RSP, sizeof(rsp), &rsp);
+
+                release_sock(sk);
+                return 0;
+        }
+
+        release_sock(sk);
+
+        return bt_sock_recvmsg(iocb, sock, msg, len, flags);
+}
+
 static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __user *optval, int optlen)
 {
         struct sock *sk = sock->sk;
@@ -1156,6 +1213,7 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname, ch
 {
         struct sock *sk = sock->sk;
         int err = 0;
+        u32 opt;
 
         BT_DBG("sk %p", sk);
 
@@ -1165,6 +1223,20 @@ static int l2cap_sock_setsockopt(struct socket *sock, int level, int optname, ch
         lock_sock(sk);
 
         switch (optname) {
+        case BT_DEFER_SETUP:
+                if (sk->sk_state != BT_BOUND && sk->sk_state != BT_LISTEN) {
+                        err = -EINVAL;
+                        break;
+                }
+
+                if (get_user(opt, (u32 __user *) optval)) {
+                        err = -EFAULT;
+                        break;
+                }
+
+                bt_sk(sk)->defer_setup = opt;
+                break;
+
         default:
                 err = -ENOPROTOOPT;
                 break;
@@ -1207,7 +1279,9 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, char __us
                 break;
 
         case L2CAP_CONNINFO:
-                if (sk->sk_state != BT_CONNECTED) {
+                if (sk->sk_state != BT_CONNECTED &&
+                                        !(sk->sk_state == BT_CONNECT2 &&
+                                                bt_sk(sk)->defer_setup)) {
                         err = -ENOTCONN;
                         break;
                 }
@@ -1246,6 +1320,17 @@ static int l2cap_sock_getsockopt(struct socket *sock, int level, int optname, ch
         lock_sock(sk);
 
         switch (optname) {
+        case BT_DEFER_SETUP:
+                if (sk->sk_state != BT_BOUND && sk->sk_state != BT_LISTEN) {
+                        err = -EINVAL;
+                        break;
+                }
+
+                if (put_user(bt_sk(sk)->defer_setup, (u32 __user *) optval))
+                        err = -EFAULT;
+
+                break;
+
         default:
                 err = -ENOPROTOOPT;
                 break;
@@ -1670,9 +1755,16 @@ static inline int l2cap_connect_req(struct l2cap_conn *conn, struct l2cap_cmd_hd
 
         if (conn->info_state & L2CAP_INFO_FEAT_MASK_REQ_SENT) {
                 if (l2cap_check_link_mode(sk)) {
-                        sk->sk_state = BT_CONFIG;
-                        result = L2CAP_CR_SUCCESS;
-                        status = L2CAP_CS_NO_INFO;
+                        if (bt_sk(sk)->defer_setup) {
+                                sk->sk_state = BT_CONNECT2;
+                                result = L2CAP_CR_PEND;
+                                status = L2CAP_CS_AUTHOR_PEND;
+                                parent->sk_data_ready(parent, 0);
+                        } else {
+                                sk->sk_state = BT_CONFIG;
+                                result = L2CAP_CR_SUCCESS;
+                                status = L2CAP_CS_NO_INFO;
+                        }
                 } else {
                         sk->sk_state = BT_CONNECT2;
                         result = L2CAP_CR_PEND;
@@ -2494,7 +2586,7 @@ static const struct proto_ops l2cap_sock_ops = {
         .accept         = l2cap_sock_accept,
         .getname        = l2cap_sock_getname,
         .sendmsg        = l2cap_sock_sendmsg,
-        .recvmsg        = bt_sock_recvmsg,
+        .recvmsg        = l2cap_sock_recvmsg,
         .poll           = bt_sock_poll,
         .ioctl          = bt_sock_ioctl,
         .mmap           = sock_no_mmap,