Bluetooth: Add support for deferring RFCOMM connection setup

In order to decide if listening RFCOMM 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.

The connection setup is done after reading from the socket for the
first time. Until then writing to the socket returns ENOTCONN.

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

2 files changed, 84 insertions, 16 deletions

diff --git a/net/bluetooth/rfcomm/core.c b/net/bluetooth/rfcomm/core.c
index acd84fd524b8..edee49e00fbf 100644
--- a/net/bluetooth/rfcomm/core.c
+++ b/net/bluetooth/rfcomm/core.c
@@ -421,9 +421,16 @@ static int __rfcomm_dlc_close(struct rfcomm_dlc *d, int err)
                         d, d->state, d->dlci, err, s);
 
         switch (d->state) {
-        case BT_CONNECTED:
-        case BT_CONFIG:
         case BT_CONNECT:
+        case BT_CONFIG:
+                if (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {
+                        set_bit(RFCOMM_AUTH_REJECT, &d->flags);
+                        rfcomm_schedule(RFCOMM_SCHED_AUTH);
+                        break;
+                }
+                /* Fall through */
+
+        case BT_CONNECTED:
                 d->state = BT_DISCONN;
                 if (skb_queue_empty(&d->tx_queue)) {
                         rfcomm_send_disc(s, d->dlci);
@@ -434,6 +441,14 @@ static int __rfcomm_dlc_close(struct rfcomm_dlc *d, int err)
                 }
                 break;
 
+        case BT_OPEN:
+                if (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {
+                        set_bit(RFCOMM_AUTH_REJECT, &d->flags);
+                        rfcomm_schedule(RFCOMM_SCHED_AUTH);
+                        break;
+                }
+                /* Fall through */
+
         default:
                 rfcomm_dlc_clear_timer(d);
 
@@ -1162,7 +1177,7 @@ static int rfcomm_recv_disc(struct rfcomm_session *s, u8 dlci)
         return 0;
 }
 
-static void rfcomm_dlc_accept(struct rfcomm_dlc *d)
+void rfcomm_dlc_accept(struct rfcomm_dlc *d)
 {
         struct sock *sk = d->session->sock->sk;
 
@@ -1181,6 +1196,20 @@ static void rfcomm_dlc_accept(struct rfcomm_dlc *d)
         rfcomm_send_msc(d->session, 1, d->dlci, d->v24_sig);
 }
 
+static void rfcomm_check_accept(struct rfcomm_dlc *d)
+{
+        if (rfcomm_check_link_mode(d)) {
+                set_bit(RFCOMM_AUTH_PENDING, &d->flags);
+                rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
+        } else {
+                if (d->defer_setup) {
+                        set_bit(RFCOMM_DEFER_SETUP, &d->flags);
+                        rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
+                } else
+                        rfcomm_dlc_accept(d);
+        }
+}
+
 static int rfcomm_recv_sabm(struct rfcomm_session *s, u8 dlci)
 {
         struct rfcomm_dlc *d;
@@ -1203,11 +1232,7 @@ static int rfcomm_recv_sabm(struct rfcomm_session *s, u8 dlci)
         if (d) {
                 if (d->state == BT_OPEN) {
                         /* DLC was previously opened by PN request */
-                        if (rfcomm_check_link_mode(d)) {
-                                set_bit(RFCOMM_AUTH_PENDING, &d->flags);
-                                rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
-                        } else
-                                rfcomm_dlc_accept(d);
+                        rfcomm_check_accept(d);
                 }
                 return 0;
         }
@@ -1219,11 +1244,7 @@ static int rfcomm_recv_sabm(struct rfcomm_session *s, u8 dlci)
                 d->addr = __addr(s->initiator, dlci);
                 rfcomm_dlc_link(s, d);
 
-                if (rfcomm_check_link_mode(d)) {
-                        set_bit(RFCOMM_AUTH_PENDING, &d->flags);
-                        rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
-                } else
-                        rfcomm_dlc_accept(d);
+                rfcomm_check_accept(d);
         } else {
                 rfcomm_send_dm(s, dlci);
         }
@@ -1717,8 +1738,13 @@ static inline void rfcomm_process_dlcs(struct rfcomm_session *s)
                         if (d->out) {
                                 rfcomm_send_pn(s, 1, d);
                                 rfcomm_dlc_set_timer(d, RFCOMM_CONN_TIMEOUT);
-                        } else
-                                rfcomm_dlc_accept(d);
+                        } else {
+                                if (d->defer_setup) {
+                                        set_bit(RFCOMM_DEFER_SETUP, &d->flags);
+                                        rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
+                                } else
+                                        rfcomm_dlc_accept(d);
+                        }
                         if (d->link_mode & RFCOMM_LM_SECURE) {
                                 struct sock *sk = s->sock->sk;
                                 hci_conn_change_link_key(l2cap_pi(sk)->conn->hcon);
diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
index 65dd7133d72b..d37a829a81e4 100644
--- a/net/bluetooth/rfcomm/sock.c
+++ b/net/bluetooth/rfcomm/sock.c
@@ -262,8 +262,10 @@ static void rfcomm_sock_init(struct sock *sk, struct sock *parent)
         if (parent) {
                 sk->sk_type = parent->sk_type;
                 pi->link_mode = rfcomm_pi(parent)->link_mode;
+                pi->dlc->defer_setup = bt_sk(parent)->defer_setup;
         } else {
                 pi->link_mode = 0;
+                pi->dlc->defer_setup = 0;
         }
 
         pi->dlc->link_mode = pi->link_mode;
@@ -554,6 +556,9 @@ static int rfcomm_sock_sendmsg(struct kiocb *iocb, struct socket *sock,
         struct sk_buff *skb;
         int sent = 0;
 
+        if (test_bit(RFCOMM_DEFER_SETUP, &d->flags))
+                return -ENOTCONN;
+
         if (msg->msg_flags & MSG_OOB)
                 return -EOPNOTSUPP;
 
@@ -633,10 +638,16 @@ static int rfcomm_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
                                struct msghdr *msg, size_t size, int flags)
 {
         struct sock *sk = sock->sk;
+        struct rfcomm_dlc *d = rfcomm_pi(sk)->dlc;
         int err = 0;
         size_t target, copied = 0;
         long timeo;
 
+        if (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {
+                rfcomm_dlc_accept(d);
+                return 0;
+        }
+
         if (flags & MSG_OOB)
                 return -EOPNOTSUPP;
 
@@ -746,6 +757,7 @@ static int rfcomm_sock_setsockopt(struct socket *sock, int level, int optname, c
 {
         struct sock *sk = sock->sk;
         int err = 0;
+        u32 opt;
 
         BT_DBG("sk %p", sk);
 
@@ -755,6 +767,20 @@ static int rfcomm_sock_setsockopt(struct socket *sock, int level, int optname, c
         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;
@@ -785,7 +811,8 @@ static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname, char __u
                 break;
 
         case RFCOMM_CONNINFO:
-                if (sk->sk_state != BT_CONNECTED) {
+                if (sk->sk_state != BT_CONNECTED &&
+                                        !rfcomm_pi(sk)->dlc->defer_setup) {
                         err = -ENOTCONN;
                         break;
                 }
@@ -826,6 +853,17 @@ static int rfcomm_sock_getsockopt(struct socket *sock, int level, int optname, c
         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;
@@ -938,6 +976,10 @@ int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc *
 
 done:
         bh_unlock_sock(parent);
+
+        if (bt_sk(parent)->defer_setup)
+                parent->sk_state_change(parent);
+
         return result;
 }