xref: /linux/net/bluetooth/rfcomm/core.c (revision 8e8cd9a4c6dc006e9bd51b8ad0079fb4576b48d3)

// SPDX-License-Identifier: GPL-2.0
/*
   RFCOMM implementation for Linux Bluetooth stack (BlueZ).
   Copyright (C) 2002 Maxim Krasnyansky <maxk@qualcomm.com>
   Copyright (C) 2002 Marcel Holtmann <marcel@holtmann.org>

   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
   IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
   CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

   ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
   COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
   SOFTWARE IS DISCLAIMED.
*/

/*
 * Bluetooth RFCOMM core.
 */

#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/kthread.h>
#include <linux/unaligned.h>

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>
#include <net/bluetooth/l2cap.h>
#include <net/bluetooth/rfcomm.h>

#include <trace/events/sock.h>

#define VERSION "1.11"

static bool disable_cfc;
static bool l2cap_ertm;
static int channel_mtu = -1;

static struct task_struct *rfcomm_thread;

static DEFINE_MUTEX(rfcomm_mutex);
#define rfcomm_lock()	mutex_lock(&rfcomm_mutex)
#define rfcomm_unlock()	mutex_unlock(&rfcomm_mutex)


static LIST_HEAD(session_list);

static int rfcomm_send_frame(struct rfcomm_session *s, u8 *data, int len);
static int rfcomm_send_sabm(struct rfcomm_session *s, u8 dlci);
static int rfcomm_send_disc(struct rfcomm_session *s, u8 dlci);
static int rfcomm_queue_disc(struct rfcomm_dlc *d);
static int rfcomm_send_nsc(struct rfcomm_session *s, int cr, u8 type);
static int rfcomm_send_pn(struct rfcomm_session *s, int cr, struct rfcomm_dlc *d);
static int rfcomm_send_msc(struct rfcomm_session *s, int cr, u8 dlci, u8 v24_sig);
static int rfcomm_send_test(struct rfcomm_session *s, int cr, u8 *pattern, int len);
static int rfcomm_send_credits(struct rfcomm_session *s, u8 addr, u8 credits);
static void rfcomm_make_uih(struct sk_buff *skb, u8 addr);

static void rfcomm_process_connect(struct rfcomm_session *s);

static struct socket *rfcomm_session_connect(bdaddr_t *src, bdaddr_t *dst,
					     u8 sec_level, int *err);
static struct rfcomm_session *rfcomm_session_add(struct socket *sock, int state);
static struct rfcomm_session *rfcomm_session_get(bdaddr_t *src, bdaddr_t *dst);
static struct rfcomm_session *rfcomm_session_del(struct rfcomm_session *s);

/* ---- RFCOMM frame parsing macros ---- */
#define __get_dlci(b)     ((b & 0xfc) >> 2)
#define __get_type(b)     ((b & 0xef))

#define __test_ea(b)      ((b & 0x01))
#define __test_cr(b)      (!!(b & 0x02))
#define __test_pf(b)      (!!(b & 0x10))

#define __session_dir(s)  ((s)->initiator ? 0x00 : 0x01)

#define __addr(cr, dlci)       (((dlci & 0x3f) << 2) | (cr << 1) | 0x01)
#define __ctrl(type, pf)       (((type & 0xef) | (pf << 4)))
#define __dlci(dir, chn)       (((chn & 0x1f) << 1) | dir)
#define __srv_channel(dlci)    (dlci >> 1)

#define __len8(len)       (((len) << 1) | 1)
#define __len16(len)      ((len) << 1)

/* MCC macros */
#define __mcc_type(cr, type)   (((type << 2) | (cr << 1) | 0x01))
#define __get_mcc_type(b) ((b & 0xfc) >> 2)
#define __get_mcc_len(b)  ((b & 0xfe) >> 1)

/* RPN macros */
#define __rpn_line_settings(data, stop, parity)  ((data & 0x3) | ((stop & 0x1) << 2) | ((parity & 0x7) << 3))
#define __get_rpn_data_bits(line) ((line) & 0x3)
#define __get_rpn_stop_bits(line) (((line) >> 2) & 0x1)
#define __get_rpn_parity(line)    (((line) >> 3) & 0x7)

static DECLARE_WAIT_QUEUE_HEAD(rfcomm_wq);

static void rfcomm_schedule(void)
{
	wake_up_all(&rfcomm_wq);
}

/* ---- RFCOMM FCS computation ---- */

/* reversed, 8-bit, poly=0x07 */
static unsigned char rfcomm_crc_table[256] = {
	0x00, 0x91, 0xe3, 0x72, 0x07, 0x96, 0xe4, 0x75,
	0x0e, 0x9f, 0xed, 0x7c, 0x09, 0x98, 0xea, 0x7b,
	0x1c, 0x8d, 0xff, 0x6e, 0x1b, 0x8a, 0xf8, 0x69,
	0x12, 0x83, 0xf1, 0x60, 0x15, 0x84, 0xf6, 0x67,

	0x38, 0xa9, 0xdb, 0x4a, 0x3f, 0xae, 0xdc, 0x4d,
	0x36, 0xa7, 0xd5, 0x44, 0x31, 0xa0, 0xd2, 0x43,
	0x24, 0xb5, 0xc7, 0x56, 0x23, 0xb2, 0xc0, 0x51,
	0x2a, 0xbb, 0xc9, 0x58, 0x2d, 0xbc, 0xce, 0x5f,

	0x70, 0xe1, 0x93, 0x02, 0x77, 0xe6, 0x94, 0x05,
	0x7e, 0xef, 0x9d, 0x0c, 0x79, 0xe8, 0x9a, 0x0b,
	0x6c, 0xfd, 0x8f, 0x1e, 0x6b, 0xfa, 0x88, 0x19,
	0x62, 0xf3, 0x81, 0x10, 0x65, 0xf4, 0x86, 0x17,

	0x48, 0xd9, 0xab, 0x3a, 0x4f, 0xde, 0xac, 0x3d,
	0x46, 0xd7, 0xa5, 0x34, 0x41, 0xd0, 0xa2, 0x33,
	0x54, 0xc5, 0xb7, 0x26, 0x53, 0xc2, 0xb0, 0x21,
	0x5a, 0xcb, 0xb9, 0x28, 0x5d, 0xcc, 0xbe, 0x2f,

	0xe0, 0x71, 0x03, 0x92, 0xe7, 0x76, 0x04, 0x95,
	0xee, 0x7f, 0x0d, 0x9c, 0xe9, 0x78, 0x0a, 0x9b,
	0xfc, 0x6d, 0x1f, 0x8e, 0xfb, 0x6a, 0x18, 0x89,
	0xf2, 0x63, 0x11, 0x80, 0xf5, 0x64, 0x16, 0x87,

	0xd8, 0x49, 0x3b, 0xaa, 0xdf, 0x4e, 0x3c, 0xad,
	0xd6, 0x47, 0x35, 0xa4, 0xd1, 0x40, 0x32, 0xa3,
	0xc4, 0x55, 0x27, 0xb6, 0xc3, 0x52, 0x20, 0xb1,
	0xca, 0x5b, 0x29, 0xb8, 0xcd, 0x5c, 0x2e, 0xbf,

	0x90, 0x01, 0x73, 0xe2, 0x97, 0x06, 0x74, 0xe5,
	0x9e, 0x0f, 0x7d, 0xec, 0x99, 0x08, 0x7a, 0xeb,
	0x8c, 0x1d, 0x6f, 0xfe, 0x8b, 0x1a, 0x68, 0xf9,
	0x82, 0x13, 0x61, 0xf0, 0x85, 0x14, 0x66, 0xf7,

	0xa8, 0x39, 0x4b, 0xda, 0xaf, 0x3e, 0x4c, 0xdd,
	0xa6, 0x37, 0x45, 0xd4, 0xa1, 0x30, 0x42, 0xd3,
	0xb4, 0x25, 0x57, 0xc6, 0xb3, 0x22, 0x50, 0xc1,
	0xba, 0x2b, 0x59, 0xc8, 0xbd, 0x2c, 0x5e, 0xcf
};

/* CRC on 2 bytes */
#define __crc(data) (rfcomm_crc_table[rfcomm_crc_table[0xff ^ data[0]] ^ data[1]])

/* FCS on 2 bytes */
static inline u8 __fcs(u8 *data)
{
	return 0xff - __crc(data);
}

/* FCS on 3 bytes */
static inline u8 __fcs2(u8 *data)
{
	return 0xff - rfcomm_crc_table[__crc(data) ^ data[2]];
}

/* Check FCS */
static inline int __check_fcs(u8 *data, int type, u8 fcs)
{
	u8 f = __crc(data);

	if (type != RFCOMM_UIH)
		f = rfcomm_crc_table[f ^ data[2]];

	return rfcomm_crc_table[f ^ fcs] != 0xcf;
}

/* ---- L2CAP callbacks ---- */
static void rfcomm_l2state_change(struct sock *sk)
{
	BT_DBG("%p state %d", sk, sk->sk_state);
	rfcomm_schedule();
}

static void rfcomm_l2data_ready(struct sock *sk)
{
	trace_sk_data_ready(sk);

	BT_DBG("%p", sk);
	rfcomm_schedule();
}

static int rfcomm_l2sock_create(struct socket **sock)
{
	int err;

	BT_DBG("");

	err = sock_create_kern(&init_net, PF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP, sock);
	if (!err) {
		struct sock *sk = (*sock)->sk;
		sk->sk_data_ready   = rfcomm_l2data_ready;
		sk->sk_state_change = rfcomm_l2state_change;
	}
	return err;
}

static int rfcomm_check_security(struct rfcomm_dlc *d)
{
	struct sock *sk = d->session->sock->sk;
	struct l2cap_conn *conn = l2cap_pi(sk)->chan->conn;

	__u8 auth_type;

	switch (d->sec_level) {
	case BT_SECURITY_HIGH:
	case BT_SECURITY_FIPS:
		auth_type = HCI_AT_GENERAL_BONDING_MITM;
		break;
	case BT_SECURITY_MEDIUM:
		auth_type = HCI_AT_GENERAL_BONDING;
		break;
	default:
		auth_type = HCI_AT_NO_BONDING;
		break;
	}

	return hci_conn_security(conn->hcon, d->sec_level, auth_type,
				 d->out);
}

static void rfcomm_session_timeout(struct timer_list *t)
{
	struct rfcomm_session *s = timer_container_of(s, t, timer);

	BT_DBG("session %p state %ld", s, s->state);

	set_bit(RFCOMM_TIMED_OUT, &s->flags);
	rfcomm_schedule();
}

static void rfcomm_session_set_timer(struct rfcomm_session *s, long timeout)
{
	BT_DBG("session %p state %ld timeout %ld", s, s->state, timeout);

	mod_timer(&s->timer, jiffies + timeout);
}

static void rfcomm_session_clear_timer(struct rfcomm_session *s)
{
	BT_DBG("session %p state %ld", s, s->state);

	timer_delete_sync(&s->timer);
}

/* ---- RFCOMM DLCs ---- */
static void rfcomm_dlc_timeout(struct timer_list *t)
{
	struct rfcomm_dlc *d = timer_container_of(d, t, timer);

	BT_DBG("dlc %p state %ld", d, d->state);

	set_bit(RFCOMM_TIMED_OUT, &d->flags);
	rfcomm_dlc_put(d);
	rfcomm_schedule();
}

static void rfcomm_dlc_set_timer(struct rfcomm_dlc *d, long timeout)
{
	BT_DBG("dlc %p state %ld timeout %ld", d, d->state, timeout);

	if (!mod_timer(&d->timer, jiffies + timeout))
		rfcomm_dlc_hold(d);
}

static void rfcomm_dlc_clear_timer(struct rfcomm_dlc *d)
{
	BT_DBG("dlc %p state %ld", d, d->state);

	if (timer_delete(&d->timer))
		rfcomm_dlc_put(d);
}

static void rfcomm_dlc_clear_state(struct rfcomm_dlc *d)
{
	BT_DBG("%p", d);

	d->state      = BT_OPEN;
	d->flags      = 0;
	d->mscex      = 0;
	d->sec_level  = BT_SECURITY_LOW;
	d->mtu        = RFCOMM_DEFAULT_MTU;
	d->v24_sig    = RFCOMM_V24_RTC | RFCOMM_V24_RTR | RFCOMM_V24_DV;

	d->cfc        = RFCOMM_CFC_DISABLED;
	d->rx_credits = RFCOMM_DEFAULT_CREDITS;
}

struct rfcomm_dlc *rfcomm_dlc_alloc(gfp_t prio)
{
	struct rfcomm_dlc *d = kzalloc_obj(*d, prio);

	if (!d)
		return NULL;

	timer_setup(&d->timer, rfcomm_dlc_timeout, 0);

	skb_queue_head_init(&d->tx_queue);
	mutex_init(&d->lock);
	refcount_set(&d->refcnt, 1);

	rfcomm_dlc_clear_state(d);

	BT_DBG("%p", d);

	return d;
}

void rfcomm_dlc_free(struct rfcomm_dlc *d)
{
	BT_DBG("%p", d);

	skb_queue_purge(&d->tx_queue);
	kfree(d);
}

static void rfcomm_dlc_link(struct rfcomm_session *s, struct rfcomm_dlc *d)
{
	BT_DBG("dlc %p session %p", d, s);

	rfcomm_session_clear_timer(s);
	rfcomm_dlc_hold(d);
	list_add(&d->list, &s->dlcs);
	d->session = s;
}

static void rfcomm_dlc_unlink(struct rfcomm_dlc *d)
{
	struct rfcomm_session *s = d->session;

	BT_DBG("dlc %p refcnt %d session %p", d, refcount_read(&d->refcnt), s);

	list_del(&d->list);
	d->session = NULL;
	rfcomm_dlc_put(d);

	if (list_empty(&s->dlcs))
		rfcomm_session_set_timer(s, RFCOMM_IDLE_TIMEOUT);
}

static struct rfcomm_dlc *rfcomm_dlc_get(struct rfcomm_session *s, u8 dlci)
{
	struct rfcomm_dlc *d;

	list_for_each_entry(d, &s->dlcs, list)
		if (d->dlci == dlci)
			return d;

	return NULL;
}

static int rfcomm_check_channel(u8 channel)
{
	return channel < 1 || channel > 30;
}

static int __rfcomm_dlc_open(struct rfcomm_dlc *d, struct rfcomm_session *s,
			     u8 channel)
{
	u8 dlci;

	BT_DBG("dlc %p state %ld session %p channel %d",
	       d, d->state, s, channel);

	if (d->state != BT_OPEN && d->state != BT_CLOSED)
		return 0;

	dlci = __dlci(__session_dir(s), channel);

	/* Check if DLCI already exists */
	if (rfcomm_dlc_get(s, dlci))
		return -EBUSY;

	rfcomm_dlc_clear_state(d);

	d->dlci     = dlci;
	d->addr     = __addr(s->initiator, dlci);
	d->priority = 7;

	d->state = BT_CONFIG;
	rfcomm_dlc_link(s, d);

	d->out = 1;

	d->mtu = s->mtu;
	d->cfc = (s->cfc == RFCOMM_CFC_UNKNOWN) ? 0 : s->cfc;

	if (s->state == BT_CONNECTED) {
		if (rfcomm_check_security(d))
			rfcomm_send_pn(s, 1, d);
		else
			set_bit(RFCOMM_AUTH_PENDING, &d->flags);
	}

	rfcomm_dlc_set_timer(d, RFCOMM_CONN_TIMEOUT);

	return 0;
}

int rfcomm_dlc_open(struct rfcomm_dlc *d, bdaddr_t *src, bdaddr_t *dst, u8 channel)
{
	struct rfcomm_session *s;
	struct socket *sock;
	int err;

	BT_DBG("dlc %p state %ld %pMR -> %pMR channel %d",
	       d, d->state, src, dst, channel);

	if (rfcomm_check_channel(channel))
		return -EINVAL;

	rfcomm_lock();

	clear_bit(RFCOMM_CLOSED, &d->flags);

	/* Do not page the remote device for a DLC that cannot be opened
	 * anyway.  __rfcomm_dlc_open() looks at the state again once the
	 * lock has been re-acquired below.
	 */
	if (d->state != BT_OPEN && d->state != BT_CLOSED) {
		rfcomm_unlock();
		return 0;
	}

	s = rfcomm_session_get(src, dst);
	if (s) {
		err = __rfcomm_dlc_open(d, s, channel);
		rfcomm_unlock();
		return err;
	}
	rfcomm_unlock();

	/* There is no session for this pair yet.  kernel_connect() ends up in
	 * l2cap_chan_connect(), which takes hdev->lock, and the HCI event
	 * path takes rfcomm_mutex while holding hdev->lock, so the socket has
	 * to be connected with rfcomm_mutex released.
	 */
	sock = rfcomm_session_connect(src, dst, d->sec_level, &err);
	if (!sock)
		return err;

	rfcomm_lock();

	/* The DLC may have been closed while the socket was connecting.  It
	 * was not on a session, so rfcomm_dlc_close() could only mark it;
	 * attaching it now would leave it with no owner.
	 */
	if (test_bit(RFCOMM_CLOSED, &d->flags)) {
		rfcomm_unlock();
		sock_release(sock);
		return -ECONNRESET;
	}

	/* Another opener may have added a session for the same pair in the
	 * meantime; that one is used and this socket is dropped.
	 */
	s = rfcomm_session_get(src, dst);
	if (!s) {
		s = rfcomm_session_add(sock, BT_BOUND);
		if (s) {
			s->initiator = 1;
			sock = NULL;
		}
	}

	err = s ? __rfcomm_dlc_open(d, s, channel) : -ENOMEM;

	rfcomm_unlock();

	if (sock)
		sock_release(sock);

	/* Over an existing ACL link the connection can complete before the
	 * session reaches the list, and that wakeup is then lost, so let
	 * krfcommd look at the socket state now.
	 */
	rfcomm_schedule();

	return err;
}

static void __rfcomm_dlc_disconn(struct rfcomm_dlc *d)
{
	struct rfcomm_session *s = d->session;

	d->state = BT_DISCONN;
	if (skb_queue_empty(&d->tx_queue)) {
		rfcomm_send_disc(s, d->dlci);
		rfcomm_dlc_set_timer(d, RFCOMM_DISC_TIMEOUT);
	} else {
		rfcomm_queue_disc(d);
		rfcomm_dlc_set_timer(d, RFCOMM_DISC_TIMEOUT * 2);
	}
}

static int __rfcomm_dlc_close(struct rfcomm_dlc *d, int err)
{
	struct rfcomm_session *s = d->session;
	if (!s)
		return 0;

	BT_DBG("dlc %p state %ld dlci %d err %d session %p",
			d, d->state, d->dlci, err, s);

	switch (d->state) {
	case BT_CONNECT:
	case BT_CONFIG:
	case BT_OPEN:
	case BT_CONNECT2:
		if (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {
			set_bit(RFCOMM_AUTH_REJECT, &d->flags);
			rfcomm_schedule();
			return 0;
		}
	}

	switch (d->state) {
	case BT_CONNECT:
	case BT_CONNECTED:
		__rfcomm_dlc_disconn(d);
		break;

	case BT_CONFIG:
		if (s->state != BT_BOUND) {
			__rfcomm_dlc_disconn(d);
			break;
		}
		/* if closing a dlc in a session that hasn't been started,
		 * just close and unlink the dlc
		 */
		fallthrough;

	default:
		rfcomm_dlc_clear_timer(d);

		rfcomm_dlc_lock(d);
		d->state = BT_CLOSED;
		d->state_change(d, err);
		rfcomm_dlc_unlock(d);

		skb_queue_purge(&d->tx_queue);
		rfcomm_dlc_unlink(d);
	}

	return 0;
}

int rfcomm_dlc_close(struct rfcomm_dlc *d, int err)
{
	int r = 0;
	struct rfcomm_dlc *d_list;
	struct rfcomm_session *s, *s_list;

	BT_DBG("dlc %p state %ld dlci %d err %d", d, d->state, d->dlci, err);

	rfcomm_lock();

	s = d->session;
	if (!s) {
		/* Not on a session yet: rfcomm_dlc_open() may be connecting a
		 * socket for it with rfcomm_mutex released.  Leave a mark so
		 * that it does not attach the DLC once it holds the lock again.
		 */
		set_bit(RFCOMM_CLOSED, &d->flags);
		goto no_session;
	}

	/* after waiting on the mutex check the session still exists
	 * then check the dlc still exists
	 */
	list_for_each_entry(s_list, &session_list, list) {
		if (s_list == s) {
			list_for_each_entry(d_list, &s->dlcs, list) {
				if (d_list == d) {
					r = __rfcomm_dlc_close(d, err);
					break;
				}
			}
			break;
		}
	}

no_session:
	rfcomm_unlock();
	return r;
}

struct rfcomm_dlc *rfcomm_dlc_exists(bdaddr_t *src, bdaddr_t *dst, u8 channel)
{
	struct rfcomm_session *s;
	struct rfcomm_dlc *dlc = NULL;
	u8 dlci;

	if (rfcomm_check_channel(channel))
		return ERR_PTR(-EINVAL);

	rfcomm_lock();
	s = rfcomm_session_get(src, dst);
	if (s) {
		dlci = __dlci(__session_dir(s), channel);
		dlc = rfcomm_dlc_get(s, dlci);
	}
	rfcomm_unlock();
	return dlc;
}

static int rfcomm_dlc_send_frag(struct rfcomm_dlc *d, struct sk_buff *frag)
{
	int len = frag->len;

	BT_DBG("dlc %p mtu %d len %d", d, d->mtu, len);

	if (len > d->mtu)
		return -EINVAL;

	rfcomm_make_uih(frag, d->addr);
	__skb_queue_tail(&d->tx_queue, frag);

	return len;
}

int rfcomm_dlc_send(struct rfcomm_dlc *d, struct sk_buff *skb)
{
	unsigned long flags;
	struct sk_buff *frag, *next;
	int len;

	if (d->state != BT_CONNECTED)
		return -ENOTCONN;

	frag = skb_shinfo(skb)->frag_list;
	skb_shinfo(skb)->frag_list = NULL;

	/* Queue all fragments atomically. */
	spin_lock_irqsave(&d->tx_queue.lock, flags);

	len = rfcomm_dlc_send_frag(d, skb);
	if (len < 0 || !frag)
		goto unlock;

	for (; frag; frag = next) {
		int ret;

		next = frag->next;

		ret = rfcomm_dlc_send_frag(d, frag);
		if (ret < 0) {
			dev_kfree_skb_irq(frag);
			goto unlock;
		}

		len += ret;
	}

unlock:
	spin_unlock_irqrestore(&d->tx_queue.lock, flags);

	if (len > 0 && !test_bit(RFCOMM_TX_THROTTLED, &d->flags))
		rfcomm_schedule();
	return len;
}

void rfcomm_dlc_send_noerror(struct rfcomm_dlc *d, struct sk_buff *skb)
{
	int len = skb->len;

	BT_DBG("dlc %p mtu %d len %d", d, d->mtu, len);

	rfcomm_make_uih(skb, d->addr);
	skb_queue_tail(&d->tx_queue, skb);

	if (d->state == BT_CONNECTED &&
	    !test_bit(RFCOMM_TX_THROTTLED, &d->flags))
		rfcomm_schedule();
}

void __rfcomm_dlc_throttle(struct rfcomm_dlc *d)
{
	BT_DBG("dlc %p state %ld", d, d->state);

	if (!d->cfc) {
		d->v24_sig |= RFCOMM_V24_FC;
		set_bit(RFCOMM_MSC_PENDING, &d->flags);
	}
	rfcomm_schedule();
}

void __rfcomm_dlc_unthrottle(struct rfcomm_dlc *d)
{
	BT_DBG("dlc %p state %ld", d, d->state);

	if (!d->cfc) {
		d->v24_sig &= ~RFCOMM_V24_FC;
		set_bit(RFCOMM_MSC_PENDING, &d->flags);
	}
	rfcomm_schedule();
}

/*
   Set/get modem status functions use _local_ status i.e. what we report
   to the other side.
   Remote status is provided by dlc->modem_status() callback.
 */
int rfcomm_dlc_set_modem_status(struct rfcomm_dlc *d, u8 v24_sig)
{
	BT_DBG("dlc %p state %ld v24_sig 0x%x",
			d, d->state, v24_sig);

	if (test_bit(RFCOMM_RX_THROTTLED, &d->flags))
		v24_sig |= RFCOMM_V24_FC;
	else
		v24_sig &= ~RFCOMM_V24_FC;

	d->v24_sig = v24_sig;

	if (!test_and_set_bit(RFCOMM_MSC_PENDING, &d->flags))
		rfcomm_schedule();

	return 0;
}

int rfcomm_dlc_get_modem_status(struct rfcomm_dlc *d, u8 *v24_sig)
{
	BT_DBG("dlc %p state %ld v24_sig 0x%x",
			d, d->state, d->v24_sig);

	*v24_sig = d->v24_sig;
	return 0;
}

/* ---- RFCOMM sessions ---- */
static struct rfcomm_session *rfcomm_session_add(struct socket *sock, int state)
{
	struct rfcomm_session *s = kzalloc_obj(*s);

	if (!s)
		return NULL;

	BT_DBG("session %p sock %p", s, sock);

	timer_setup(&s->timer, rfcomm_session_timeout, 0);

	INIT_LIST_HEAD(&s->dlcs);
	s->state = state;
	s->sock  = sock;

	s->mtu = RFCOMM_DEFAULT_MTU;
	s->cfc = disable_cfc ? RFCOMM_CFC_DISABLED : RFCOMM_CFC_UNKNOWN;

	/* Do not increment module usage count for listening sessions.
	 * Otherwise we won't be able to unload the module. */
	if (state != BT_LISTEN)
		if (!try_module_get(THIS_MODULE)) {
			kfree(s);
			return NULL;
		}

	list_add(&s->list, &session_list);

	return s;
}

static struct rfcomm_session *rfcomm_session_del(struct rfcomm_session *s)
{
	int state = s->state;

	BT_DBG("session %p state %ld", s, s->state);

	list_del(&s->list);

	rfcomm_session_clear_timer(s);
	sock_release(s->sock);
	kfree(s);

	if (state != BT_LISTEN)
		module_put(THIS_MODULE);

	return NULL;
}

static struct rfcomm_session *rfcomm_session_get(bdaddr_t *src, bdaddr_t *dst)
{
	struct rfcomm_session *s, *n;
	struct l2cap_chan *chan;
	list_for_each_entry_safe(s, n, &session_list, list) {
		chan = l2cap_pi(s->sock->sk)->chan;

		if ((!bacmp(src, BDADDR_ANY) || !bacmp(&chan->src, src)) &&
		    !bacmp(&chan->dst, dst))
			return s;
	}
	return NULL;
}

static struct rfcomm_session *rfcomm_session_close(struct rfcomm_session *s,
						   int err)
{
	struct rfcomm_dlc *d, *n;

	s->state = BT_CLOSED;

	BT_DBG("session %p state %ld err %d", s, s->state, err);

	/* Close all dlcs */
	list_for_each_entry_safe(d, n, &s->dlcs, list) {
		d->state = BT_CLOSED;
		__rfcomm_dlc_close(d, err);
	}

	rfcomm_session_clear_timer(s);
	return rfcomm_session_del(s);
}

/* Creates the L2CAP socket a new session will run on and starts connecting
 * it.  Must be called with rfcomm_mutex released.
 */
static struct socket *rfcomm_session_connect(bdaddr_t *src, bdaddr_t *dst,
					     u8 sec_level, int *err)
{
	struct sockaddr_l2 addr;
	struct socket *sock;
	struct sock *sk;

	BT_DBG("%pMR -> %pMR", src, dst);

	*err = rfcomm_l2sock_create(&sock);
	if (*err < 0)
		return NULL;

	bacpy(&addr.l2_bdaddr, src);
	addr.l2_family = AF_BLUETOOTH;
	addr.l2_psm    = 0;
	addr.l2_cid    = 0;
	addr.l2_bdaddr_type = BDADDR_BREDR;
	*err = kernel_bind(sock, (struct sockaddr_unsized *)&addr, sizeof(addr));
	if (*err < 0)
		goto failed;

	/* Set L2CAP options */
	sk = sock->sk;
	lock_sock(sk);
	/* Set MTU to 0 so L2CAP can auto select the MTU */
	l2cap_pi(sk)->chan->imtu = 0;
	l2cap_pi(sk)->chan->sec_level = sec_level;
	if (l2cap_ertm)
		l2cap_pi(sk)->chan->mode = L2CAP_MODE_ERTM;
	release_sock(sk);

	bacpy(&addr.l2_bdaddr, dst);
	addr.l2_family = AF_BLUETOOTH;
	addr.l2_psm    = cpu_to_le16(L2CAP_PSM_RFCOMM);
	addr.l2_cid    = 0;
	addr.l2_bdaddr_type = BDADDR_BREDR;
	*err = kernel_connect(sock, (struct sockaddr_unsized *)&addr, sizeof(addr), O_NONBLOCK);
	if (*err && *err != -EINPROGRESS)
		goto failed;

	return sock;

failed:
	sock_release(sock);
	return NULL;
}

void rfcomm_session_getaddr(struct rfcomm_session *s, bdaddr_t *src, bdaddr_t *dst)
{
	struct l2cap_chan *chan = l2cap_pi(s->sock->sk)->chan;
	if (src)
		bacpy(src, &chan->src);
	if (dst)
		bacpy(dst, &chan->dst);
}

/* ---- RFCOMM frame sending ---- */
static int rfcomm_send_frame(struct rfcomm_session *s, u8 *data, int len)
{
	struct kvec iv = { data, len };
	struct msghdr msg;

	BT_DBG("session %p len %d", s, len);

	memset(&msg, 0, sizeof(msg));

	return kernel_sendmsg(s->sock, &msg, &iv, 1, len);
}

static int rfcomm_send_cmd(struct rfcomm_session *s, struct rfcomm_cmd *cmd)
{
	BT_DBG("%p cmd %u", s, cmd->ctrl);

	return rfcomm_send_frame(s, (void *) cmd, sizeof(*cmd));
}

static int rfcomm_send_sabm(struct rfcomm_session *s, u8 dlci)
{
	struct rfcomm_cmd cmd;

	BT_DBG("%p dlci %d", s, dlci);

	cmd.addr = __addr(s->initiator, dlci);
	cmd.ctrl = __ctrl(RFCOMM_SABM, 1);
	cmd.len  = __len8(0);
	cmd.fcs  = __fcs2((u8 *) &cmd);

	return rfcomm_send_cmd(s, &cmd);
}

static int rfcomm_send_ua(struct rfcomm_session *s, u8 dlci)
{
	struct rfcomm_cmd cmd;

	BT_DBG("%p dlci %d", s, dlci);

	cmd.addr = __addr(!s->initiator, dlci);
	cmd.ctrl = __ctrl(RFCOMM_UA, 1);
	cmd.len  = __len8(0);
	cmd.fcs  = __fcs2((u8 *) &cmd);

	return rfcomm_send_cmd(s, &cmd);
}

static int rfcomm_send_disc(struct rfcomm_session *s, u8 dlci)
{
	struct rfcomm_cmd cmd;

	BT_DBG("%p dlci %d", s, dlci);

	cmd.addr = __addr(s->initiator, dlci);
	cmd.ctrl = __ctrl(RFCOMM_DISC, 1);
	cmd.len  = __len8(0);
	cmd.fcs  = __fcs2((u8 *) &cmd);

	return rfcomm_send_cmd(s, &cmd);
}

static int rfcomm_queue_disc(struct rfcomm_dlc *d)
{
	struct rfcomm_cmd *cmd;
	struct sk_buff *skb;

	BT_DBG("dlc %p dlci %d", d, d->dlci);

	skb = alloc_skb(sizeof(*cmd), GFP_KERNEL);
	if (!skb)
		return -ENOMEM;

	cmd = __skb_put(skb, sizeof(*cmd));
	cmd->addr = d->addr;
	cmd->ctrl = __ctrl(RFCOMM_DISC, 1);
	cmd->len  = __len8(0);
	cmd->fcs  = __fcs2((u8 *) cmd);

	skb_queue_tail(&d->tx_queue, skb);
	rfcomm_schedule();
	return 0;
}

static int rfcomm_send_dm(struct rfcomm_session *s, u8 dlci)
{
	struct rfcomm_cmd cmd;

	BT_DBG("%p dlci %d", s, dlci);

	cmd.addr = __addr(!s->initiator, dlci);
	cmd.ctrl = __ctrl(RFCOMM_DM, 1);
	cmd.len  = __len8(0);
	cmd.fcs  = __fcs2((u8 *) &cmd);

	return rfcomm_send_cmd(s, &cmd);
}

static int rfcomm_send_nsc(struct rfcomm_session *s, int cr, u8 type)
{
	struct rfcomm_hdr *hdr;
	struct rfcomm_mcc *mcc;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p cr %d type %d", s, cr, type);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = __addr(s->initiator, 0);
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);
	hdr->len  = __len8(sizeof(*mcc) + 1);

	mcc = (void *) ptr; ptr += sizeof(*mcc);
	mcc->type = __mcc_type(0, RFCOMM_NSC);
	mcc->len  = __len8(1);

	/* Type that we didn't like */
	*ptr = __mcc_type(cr, type); ptr++;

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

static int rfcomm_send_pn(struct rfcomm_session *s, int cr, struct rfcomm_dlc *d)
{
	struct rfcomm_hdr *hdr;
	struct rfcomm_mcc *mcc;
	struct rfcomm_pn  *pn;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p cr %d dlci %d mtu %d", s, cr, d->dlci, d->mtu);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = __addr(s->initiator, 0);
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);
	hdr->len  = __len8(sizeof(*mcc) + sizeof(*pn));

	mcc = (void *) ptr; ptr += sizeof(*mcc);
	mcc->type = __mcc_type(cr, RFCOMM_PN);
	mcc->len  = __len8(sizeof(*pn));

	pn = (void *) ptr; ptr += sizeof(*pn);
	pn->dlci        = d->dlci;
	pn->priority    = d->priority;
	pn->ack_timer   = 0;
	pn->max_retrans = 0;

	if (s->cfc) {
		pn->flow_ctrl = cr ? 0xf0 : 0xe0;
		pn->credits = RFCOMM_DEFAULT_CREDITS;
	} else {
		pn->flow_ctrl = 0;
		pn->credits   = 0;
	}

	if (cr && channel_mtu >= 0)
		pn->mtu = cpu_to_le16(channel_mtu);
	else
		pn->mtu = cpu_to_le16(d->mtu);

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

int rfcomm_send_rpn(struct rfcomm_session *s, int cr, u8 dlci,
			u8 bit_rate, u8 data_bits, u8 stop_bits,
			u8 parity, u8 flow_ctrl_settings,
			u8 xon_char, u8 xoff_char, u16 param_mask)
{
	struct rfcomm_hdr *hdr;
	struct rfcomm_mcc *mcc;
	struct rfcomm_rpn *rpn;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p cr %d dlci %d bit_r 0x%x data_b 0x%x stop_b 0x%x parity 0x%x"
			" flwc_s 0x%x xon_c 0x%x xoff_c 0x%x p_mask 0x%x",
		s, cr, dlci, bit_rate, data_bits, stop_bits, parity,
		flow_ctrl_settings, xon_char, xoff_char, param_mask);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = __addr(s->initiator, 0);
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);
	hdr->len  = __len8(sizeof(*mcc) + sizeof(*rpn));

	mcc = (void *) ptr; ptr += sizeof(*mcc);
	mcc->type = __mcc_type(cr, RFCOMM_RPN);
	mcc->len  = __len8(sizeof(*rpn));

	rpn = (void *) ptr; ptr += sizeof(*rpn);
	rpn->dlci          = __addr(1, dlci);
	rpn->bit_rate      = bit_rate;
	rpn->line_settings = __rpn_line_settings(data_bits, stop_bits, parity);
	rpn->flow_ctrl     = flow_ctrl_settings;
	rpn->xon_char      = xon_char;
	rpn->xoff_char     = xoff_char;
	rpn->param_mask    = cpu_to_le16(param_mask);

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

int rfcomm_dlc_send_rpn(struct rfcomm_dlc *d, u8 bit_rate, u8 data_bits,
			u8 stop_bits, u8 parity, u8 flow_ctrl_settings,
			u8 xon_char, u8 xoff_char, u16 param_mask)
{
	int err = -ENOTCONN;

	rfcomm_lock();
	if (d->session)
		err = rfcomm_send_rpn(d->session, 1, d->dlci, bit_rate,
				      data_bits, stop_bits, parity,
				      flow_ctrl_settings, xon_char, xoff_char,
				      param_mask);
	rfcomm_unlock();

	return err;
}

static int rfcomm_send_rls(struct rfcomm_session *s, int cr, u8 dlci, u8 status)
{
	struct rfcomm_hdr *hdr;
	struct rfcomm_mcc *mcc;
	struct rfcomm_rls *rls;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p cr %d status 0x%x", s, cr, status);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = __addr(s->initiator, 0);
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);
	hdr->len  = __len8(sizeof(*mcc) + sizeof(*rls));

	mcc = (void *) ptr; ptr += sizeof(*mcc);
	mcc->type = __mcc_type(cr, RFCOMM_RLS);
	mcc->len  = __len8(sizeof(*rls));

	rls = (void *) ptr; ptr += sizeof(*rls);
	rls->dlci   = __addr(1, dlci);
	rls->status = status;

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

static int rfcomm_send_msc(struct rfcomm_session *s, int cr, u8 dlci, u8 v24_sig)
{
	struct rfcomm_hdr *hdr;
	struct rfcomm_mcc *mcc;
	struct rfcomm_msc *msc;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p cr %d v24 0x%x", s, cr, v24_sig);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = __addr(s->initiator, 0);
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);
	hdr->len  = __len8(sizeof(*mcc) + sizeof(*msc));

	mcc = (void *) ptr; ptr += sizeof(*mcc);
	mcc->type = __mcc_type(cr, RFCOMM_MSC);
	mcc->len  = __len8(sizeof(*msc));

	msc = (void *) ptr; ptr += sizeof(*msc);
	msc->dlci    = __addr(1, dlci);
	msc->v24_sig = v24_sig | 0x01;

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

static int rfcomm_send_fcoff(struct rfcomm_session *s, int cr)
{
	struct rfcomm_hdr *hdr;
	struct rfcomm_mcc *mcc;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p cr %d", s, cr);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = __addr(s->initiator, 0);
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);
	hdr->len  = __len8(sizeof(*mcc));

	mcc = (void *) ptr; ptr += sizeof(*mcc);
	mcc->type = __mcc_type(cr, RFCOMM_FCOFF);
	mcc->len  = __len8(0);

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

static int rfcomm_send_fcon(struct rfcomm_session *s, int cr)
{
	struct rfcomm_hdr *hdr;
	struct rfcomm_mcc *mcc;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p cr %d", s, cr);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = __addr(s->initiator, 0);
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);
	hdr->len  = __len8(sizeof(*mcc));

	mcc = (void *) ptr; ptr += sizeof(*mcc);
	mcc->type = __mcc_type(cr, RFCOMM_FCON);
	mcc->len  = __len8(0);

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

static int rfcomm_send_test(struct rfcomm_session *s, int cr, u8 *pattern, int len)
{
	struct socket *sock = s->sock;
	struct kvec iv[3];
	struct msghdr msg;
	unsigned char hdr[5], crc[1];

	if (len > 125)
		return -EINVAL;

	BT_DBG("%p cr %d", s, cr);

	hdr[0] = __addr(s->initiator, 0);
	hdr[1] = __ctrl(RFCOMM_UIH, 0);
	hdr[2] = 0x01 | ((len + 2) << 1);
	hdr[3] = 0x01 | ((cr & 0x01) << 1) | (RFCOMM_TEST << 2);
	hdr[4] = 0x01 | (len << 1);

	crc[0] = __fcs(hdr);

	iv[0].iov_base = hdr;
	iv[0].iov_len  = 5;
	iv[1].iov_base = pattern;
	iv[1].iov_len  = len;
	iv[2].iov_base = crc;
	iv[2].iov_len  = 1;

	memset(&msg, 0, sizeof(msg));

	return kernel_sendmsg(sock, &msg, iv, 3, 6 + len);
}

static int rfcomm_send_credits(struct rfcomm_session *s, u8 addr, u8 credits)
{
	struct rfcomm_hdr *hdr;
	u8 buf[16], *ptr = buf;

	BT_DBG("%p addr %d credits %d", s, addr, credits);

	hdr = (void *) ptr; ptr += sizeof(*hdr);
	hdr->addr = addr;
	hdr->ctrl = __ctrl(RFCOMM_UIH, 1);
	hdr->len  = __len8(0);

	*ptr = credits; ptr++;

	*ptr = __fcs(buf); ptr++;

	return rfcomm_send_frame(s, buf, ptr - buf);
}

static void rfcomm_make_uih(struct sk_buff *skb, u8 addr)
{
	struct rfcomm_hdr *hdr;
	int len = skb->len;
	u8 *crc;

	if (len > 127) {
		hdr = skb_push(skb, 4);
		put_unaligned(cpu_to_le16(__len16(len)), (__le16 *) &hdr->len);
	} else {
		hdr = skb_push(skb, 3);
		hdr->len = __len8(len);
	}
	hdr->addr = addr;
	hdr->ctrl = __ctrl(RFCOMM_UIH, 0);

	crc = skb_put(skb, 1);
	*crc = __fcs((void *) hdr);
}

/* ---- RFCOMM frame reception ---- */
static struct rfcomm_session *rfcomm_recv_ua(struct rfcomm_session *s, u8 dlci)
{
	BT_DBG("session %p state %ld dlci %d", s, s->state, dlci);

	if (dlci) {
		/* Data channel */
		struct rfcomm_dlc *d = rfcomm_dlc_get(s, dlci);
		if (!d) {
			rfcomm_send_dm(s, dlci);
			return s;
		}

		switch (d->state) {
		case BT_CONNECT:
			rfcomm_dlc_clear_timer(d);

			rfcomm_dlc_lock(d);
			d->state = BT_CONNECTED;
			d->state_change(d, 0);
			rfcomm_dlc_unlock(d);

			rfcomm_send_msc(s, 1, dlci, d->v24_sig);
			break;

		case BT_DISCONN:
			d->state = BT_CLOSED;
			__rfcomm_dlc_close(d, 0);

			if (list_empty(&s->dlcs)) {
				s->state = BT_DISCONN;
				rfcomm_send_disc(s, 0);
				rfcomm_session_clear_timer(s);
			}

			break;
		}
	} else {
		/* Control channel */
		switch (s->state) {
		case BT_CONNECT:
			s->state = BT_CONNECTED;
			rfcomm_process_connect(s);
			break;

		case BT_DISCONN:
			s = rfcomm_session_close(s, ECONNRESET);
			break;
		}
	}
	return s;
}

static struct rfcomm_session *rfcomm_recv_dm(struct rfcomm_session *s, u8 dlci)
{
	int err = 0;

	BT_DBG("session %p state %ld dlci %d", s, s->state, dlci);

	if (dlci) {
		/* Data DLC */
		struct rfcomm_dlc *d = rfcomm_dlc_get(s, dlci);
		if (d) {
			if (d->state == BT_CONNECT || d->state == BT_CONFIG)
				err = ECONNREFUSED;
			else
				err = ECONNRESET;

			d->state = BT_CLOSED;
			__rfcomm_dlc_close(d, err);
		}
	} else {
		if (s->state == BT_CONNECT)
			err = ECONNREFUSED;
		else
			err = ECONNRESET;

		s = rfcomm_session_close(s, err);
	}
	return s;
}

static struct rfcomm_session *rfcomm_recv_disc(struct rfcomm_session *s,
					       u8 dlci)
{
	int err = 0;

	BT_DBG("session %p state %ld dlci %d", s, s->state, dlci);

	if (dlci) {
		struct rfcomm_dlc *d = rfcomm_dlc_get(s, dlci);
		if (d) {
			rfcomm_send_ua(s, dlci);

			if (d->state == BT_CONNECT || d->state == BT_CONFIG)
				err = ECONNREFUSED;
			else
				err = ECONNRESET;

			d->state = BT_CLOSED;
			__rfcomm_dlc_close(d, err);
		} else
			rfcomm_send_dm(s, dlci);

	} else {
		rfcomm_send_ua(s, 0);

		if (s->state == BT_CONNECT)
			err = ECONNREFUSED;
		else
			err = ECONNRESET;

		s = rfcomm_session_close(s, err);
	}
	return s;
}

/* Must be called with rfcomm_mutex held, so that the session cannot be
 * unlinked from under us.
 */
static void __rfcomm_dlc_accept(struct rfcomm_dlc *d)
{
	struct sock *sk = d->session->sock->sk;
	struct l2cap_conn *conn = l2cap_pi(sk)->chan->conn;

	BT_DBG("dlc %p", d);

	rfcomm_send_ua(d->session, d->dlci);

	rfcomm_dlc_clear_timer(d);

	rfcomm_dlc_lock(d);
	d->state = BT_CONNECTED;
	d->state_change(d, 0);
	rfcomm_dlc_unlock(d);

	if (d->role_switch)
		hci_conn_switch_role(conn->hcon, 0x00);

	rfcomm_send_msc(d->session, 1, d->dlci, d->v24_sig);
}

void rfcomm_dlc_accept(struct rfcomm_dlc *d)
{
	rfcomm_lock();

	/* rfcomm_recv_disc() sets the dlc state to BT_CLOSED before calling
	 * __rfcomm_dlc_close(), so the RFCOMM_DEFER_SETUP handshake there is
	 * skipped and the session can already be unlinked by the time the
	 * deferred accept runs from rfcomm_sock_recvmsg().
	 */
	if (d->session)
		__rfcomm_dlc_accept(d);

	rfcomm_unlock();
}

static void rfcomm_check_accept(struct rfcomm_dlc *d)
{
	if (rfcomm_check_security(d)) {
		if (d->defer_setup) {
			set_bit(RFCOMM_DEFER_SETUP, &d->flags);
			rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);

			rfcomm_dlc_lock(d);
			d->state = BT_CONNECT2;
			d->state_change(d, 0);
			rfcomm_dlc_unlock(d);
		} else
			__rfcomm_dlc_accept(d);
	} else {
		set_bit(RFCOMM_AUTH_PENDING, &d->flags);
		rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
	}
}

static int rfcomm_recv_sabm(struct rfcomm_session *s, u8 dlci)
{
	struct rfcomm_dlc *d;
	u8 channel;

	BT_DBG("session %p state %ld dlci %d", s, s->state, dlci);

	if (!dlci) {
		rfcomm_send_ua(s, 0);

		if (s->state == BT_OPEN) {
			s->state = BT_CONNECTED;
			rfcomm_process_connect(s);
		}
		return 0;
	}

	/* Check if DLC exists */
	d = rfcomm_dlc_get(s, dlci);
	if (d) {
		if (d->state == BT_OPEN) {
			/* DLC was previously opened by PN request */
			rfcomm_check_accept(d);
		}
		return 0;
	}

	/* Notify socket layer about incoming connection */
	channel = __srv_channel(dlci);
	if (rfcomm_connect_ind(s, channel, &d)) {
		d->dlci = dlci;
		d->addr = __addr(s->initiator, dlci);
		rfcomm_dlc_link(s, d);

		rfcomm_check_accept(d);
	} else {
		rfcomm_send_dm(s, dlci);
	}

	return 0;
}

static int rfcomm_apply_pn(struct rfcomm_dlc *d, int cr, struct rfcomm_pn *pn)
{
	struct rfcomm_session *s = d->session;

	BT_DBG("dlc %p state %ld dlci %d mtu %d fc 0x%x credits %d",
			d, d->state, d->dlci, pn->mtu, pn->flow_ctrl, pn->credits);

	if ((pn->flow_ctrl == 0xf0 && s->cfc != RFCOMM_CFC_DISABLED) ||
						pn->flow_ctrl == 0xe0) {
		d->cfc = RFCOMM_CFC_ENABLED;
		d->tx_credits = pn->credits;
	} else {
		d->cfc = RFCOMM_CFC_DISABLED;
		set_bit(RFCOMM_TX_THROTTLED, &d->flags);
	}

	if (s->cfc == RFCOMM_CFC_UNKNOWN)
		s->cfc = d->cfc;

	d->priority = pn->priority;

	d->mtu = __le16_to_cpu(pn->mtu);

	/* MTU 0 causes an infinite loop when fragmenting in sendmsg */
	if (!d->mtu)
		d->mtu = RFCOMM_DEFAULT_MTU;

	if (cr && d->mtu > s->mtu)
		d->mtu = s->mtu;

	return 0;
}

static int rfcomm_recv_pn(struct rfcomm_session *s, int cr, struct sk_buff *skb)
{
	struct rfcomm_pn *pn;
	struct rfcomm_dlc *d;
	u8 dlci;

	pn = skb_pull_data(skb, sizeof(*pn));
	if (!pn)
		return -EILSEQ;

	dlci = pn->dlci;
	BT_DBG("session %p state %ld dlci %d", s, s->state, dlci);

	if (!dlci)
		return 0;

	d = rfcomm_dlc_get(s, dlci);
	if (d) {
		if (cr) {
			/* PN request */
			rfcomm_apply_pn(d, cr, pn);
			rfcomm_send_pn(s, 0, d);
		} else {
			/* PN response */
			switch (d->state) {
			case BT_CONFIG:
				rfcomm_apply_pn(d, cr, pn);

				d->state = BT_CONNECT;
				rfcomm_send_sabm(s, d->dlci);
				break;
			}
		}
	} else {
		u8 channel = __srv_channel(dlci);

		if (!cr)
			return 0;

		/* PN request for non existing DLC.
		 * Assume incoming connection. */
		if (rfcomm_connect_ind(s, channel, &d)) {
			d->dlci = dlci;
			d->addr = __addr(s->initiator, dlci);
			rfcomm_dlc_link(s, d);

			rfcomm_apply_pn(d, cr, pn);

			d->state = BT_OPEN;
			rfcomm_send_pn(s, 0, d);
		} else {
			rfcomm_send_dm(s, dlci);
		}
	}
	return 0;
}

static int rfcomm_recv_rpn(struct rfcomm_session *s, int cr, int len, struct sk_buff *skb)
{
	struct rfcomm_rpn *rpn;
	u8 dlci;

	u8 bit_rate  = 0;
	u8 data_bits = 0;
	u8 stop_bits = 0;
	u8 parity    = 0;
	u8 flow_ctrl = 0;
	u8 xon_char  = 0;
	u8 xoff_char = 0;
	u16 rpn_mask = RFCOMM_RPN_PM_ALL;

	if (len == 1) {
		rpn = skb_pull_data(skb, 1);
		if (!rpn)
			return -EILSEQ;

		dlci = __get_dlci(rpn->dlci);

		if (!cr)
			return 0;

		bit_rate  = RFCOMM_RPN_BR_9600;
		data_bits = RFCOMM_RPN_DATA_8;
		stop_bits = RFCOMM_RPN_STOP_1;
		parity    = RFCOMM_RPN_PARITY_NONE;
		flow_ctrl = RFCOMM_RPN_FLOW_NONE;
		xon_char  = RFCOMM_RPN_XON_CHAR;
		xoff_char = RFCOMM_RPN_XOFF_CHAR;
		goto rpn_out;
	}

	rpn = skb_pull_data(skb, sizeof(*rpn));
	if (!rpn)
		return -EILSEQ;

	dlci = __get_dlci(rpn->dlci);

	BT_DBG("dlci %d cr %d len 0x%x bitr 0x%x line 0x%x flow 0x%x xonc 0x%x xoffc 0x%x pm 0x%x",
	       dlci, cr, len, rpn->bit_rate, rpn->line_settings, rpn->flow_ctrl,
	       rpn->xon_char, rpn->xoff_char, rpn->param_mask);

	if (!cr)
		return 0;

	/* Check for sane values, ignore/accept bit_rate, 8 bits, 1 stop bit,
	 * no parity, no flow control lines, normal XON/XOFF chars */

	if (rpn->param_mask & cpu_to_le16(RFCOMM_RPN_PM_BITRATE)) {
		bit_rate = rpn->bit_rate;
		if (bit_rate > RFCOMM_RPN_BR_230400) {
			BT_DBG("RPN bit rate mismatch 0x%x", bit_rate);
			bit_rate = RFCOMM_RPN_BR_9600;
			rpn_mask ^= RFCOMM_RPN_PM_BITRATE;
		}
	}

	if (rpn->param_mask & cpu_to_le16(RFCOMM_RPN_PM_DATA)) {
		data_bits = __get_rpn_data_bits(rpn->line_settings);
		if (data_bits != RFCOMM_RPN_DATA_8) {
			BT_DBG("RPN data bits mismatch 0x%x", data_bits);
			data_bits = RFCOMM_RPN_DATA_8;
			rpn_mask ^= RFCOMM_RPN_PM_DATA;
		}
	}

	if (rpn->param_mask & cpu_to_le16(RFCOMM_RPN_PM_STOP)) {
		stop_bits = __get_rpn_stop_bits(rpn->line_settings);
		if (stop_bits != RFCOMM_RPN_STOP_1) {
			BT_DBG("RPN stop bits mismatch 0x%x", stop_bits);
			stop_bits = RFCOMM_RPN_STOP_1;
			rpn_mask ^= RFCOMM_RPN_PM_STOP;
		}
	}

	if (rpn->param_mask & cpu_to_le16(RFCOMM_RPN_PM_PARITY)) {
		parity = __get_rpn_parity(rpn->line_settings);
		if (parity != RFCOMM_RPN_PARITY_NONE) {
			BT_DBG("RPN parity mismatch 0x%x", parity);
			parity = RFCOMM_RPN_PARITY_NONE;
			rpn_mask ^= RFCOMM_RPN_PM_PARITY;
		}
	}

	if (rpn->param_mask & cpu_to_le16(RFCOMM_RPN_PM_FLOW)) {
		flow_ctrl = rpn->flow_ctrl;
		if (flow_ctrl != RFCOMM_RPN_FLOW_NONE) {
			BT_DBG("RPN flow ctrl mismatch 0x%x", flow_ctrl);
			flow_ctrl = RFCOMM_RPN_FLOW_NONE;
			rpn_mask ^= RFCOMM_RPN_PM_FLOW;
		}
	}

	if (rpn->param_mask & cpu_to_le16(RFCOMM_RPN_PM_XON)) {
		xon_char = rpn->xon_char;
		if (xon_char != RFCOMM_RPN_XON_CHAR) {
			BT_DBG("RPN XON char mismatch 0x%x", xon_char);
			xon_char = RFCOMM_RPN_XON_CHAR;
			rpn_mask ^= RFCOMM_RPN_PM_XON;
		}
	}

	if (rpn->param_mask & cpu_to_le16(RFCOMM_RPN_PM_XOFF)) {
		xoff_char = rpn->xoff_char;
		if (xoff_char != RFCOMM_RPN_XOFF_CHAR) {
			BT_DBG("RPN XOFF char mismatch 0x%x", xoff_char);
			xoff_char = RFCOMM_RPN_XOFF_CHAR;
			rpn_mask ^= RFCOMM_RPN_PM_XOFF;
		}
	}

rpn_out:
	rfcomm_send_rpn(s, 0, dlci, bit_rate, data_bits, stop_bits,
			parity, flow_ctrl, xon_char, xoff_char, rpn_mask);

	return 0;
}

static int rfcomm_recv_rls(struct rfcomm_session *s, int cr, struct sk_buff *skb)
{
	struct rfcomm_rls *rls;
	u8 dlci;

	rls = skb_pull_data(skb, sizeof(*rls));
	if (!rls)
		return -EILSEQ;

	dlci = __get_dlci(rls->dlci);
	BT_DBG("dlci %d cr %d status 0x%x", dlci, cr, rls->status);

	if (!cr)
		return 0;

	/* We should probably do something with this information here. But
	 * for now it's sufficient just to reply -- Bluetooth 1.1 says it's
	 * mandatory to recognise and respond to RLS */

	rfcomm_send_rls(s, 0, dlci, rls->status);

	return 0;
}

static int rfcomm_recv_msc(struct rfcomm_session *s, int cr, struct sk_buff *skb)
{
	struct rfcomm_msc *msc;
	struct rfcomm_dlc *d;
	u8 dlci;

	msc = skb_pull_data(skb, sizeof(*msc));
	if (!msc)
		return -EILSEQ;

	dlci = __get_dlci(msc->dlci);
	BT_DBG("dlci %d cr %d v24 0x%x", dlci, cr, msc->v24_sig);

	d = rfcomm_dlc_get(s, dlci);
	if (!d)
		return 0;

	if (cr) {
		if (msc->v24_sig & RFCOMM_V24_FC && !d->cfc)
			set_bit(RFCOMM_TX_THROTTLED, &d->flags);
		else
			clear_bit(RFCOMM_TX_THROTTLED, &d->flags);

		rfcomm_dlc_lock(d);

		d->remote_v24_sig = msc->v24_sig;

		if (d->modem_status)
			d->modem_status(d, msc->v24_sig);

		rfcomm_dlc_unlock(d);

		rfcomm_send_msc(s, 0, dlci, msc->v24_sig);

		d->mscex |= RFCOMM_MSCEX_RX;
	} else
		d->mscex |= RFCOMM_MSCEX_TX;

	return 0;
}

static int rfcomm_recv_mcc(struct rfcomm_session *s, struct sk_buff *skb)
{
	struct rfcomm_mcc *mcc;
	u8 type, cr, len;

	mcc = skb_pull_data(skb, sizeof(*mcc));
	if (!mcc)
		return -EILSEQ;

	cr   = __test_cr(mcc->type);
	type = __get_mcc_type(mcc->type);
	len  = __get_mcc_len(mcc->len);

	BT_DBG("%p type 0x%x cr %d", s, type, cr);

	switch (type) {
	case RFCOMM_PN:
		rfcomm_recv_pn(s, cr, skb);
		break;

	case RFCOMM_RPN:
		rfcomm_recv_rpn(s, cr, len, skb);
		break;

	case RFCOMM_RLS:
		rfcomm_recv_rls(s, cr, skb);
		break;

	case RFCOMM_MSC:
		rfcomm_recv_msc(s, cr, skb);
		break;

	case RFCOMM_FCOFF:
		if (cr) {
			set_bit(RFCOMM_TX_THROTTLED, &s->flags);
			rfcomm_send_fcoff(s, 0);
		}
		break;

	case RFCOMM_FCON:
		if (cr) {
			clear_bit(RFCOMM_TX_THROTTLED, &s->flags);
			rfcomm_send_fcon(s, 0);
		}
		break;

	case RFCOMM_TEST:
		if (cr)
			rfcomm_send_test(s, 0, skb->data, skb->len);
		break;

	case RFCOMM_NSC:
		break;

	default:
		BT_ERR("Unknown control type 0x%02x", type);
		rfcomm_send_nsc(s, cr, type);
		break;
	}
	return 0;
}

static int rfcomm_recv_data(struct rfcomm_session *s, u8 dlci, int pf, struct sk_buff *skb)
{
	struct rfcomm_dlc *d;

	BT_DBG("session %p state %ld dlci %d pf %d", s, s->state, dlci, pf);

	d = rfcomm_dlc_get(s, dlci);
	if (!d) {
		rfcomm_send_dm(s, dlci);
		goto drop;
	}

	if (pf && d->cfc) {
		u8 *credits = skb_pull_data(skb, 1);

		if (!credits)
			goto drop;

		d->tx_credits += *credits;
		if (d->tx_credits)
			clear_bit(RFCOMM_TX_THROTTLED, &d->flags);
	}

	if (skb->len && d->state == BT_CONNECTED) {
		rfcomm_dlc_lock(d);
		d->rx_credits--;
		d->data_ready(d, skb);
		rfcomm_dlc_unlock(d);
		return 0;
	}

drop:
	kfree_skb(skb);
	return 0;
}

static struct rfcomm_session *rfcomm_recv_frame(struct rfcomm_session *s,
						struct sk_buff *skb)
{
	struct rfcomm_hdr *hdr = (void *) skb->data;
	u8 type, dlci, fcs;

	if (!s) {
		/* no session, so free socket data */
		kfree_skb(skb);
		return s;
	}

	if (skb->len < sizeof(*hdr) + 1 ||
	    (!__test_ea(hdr->len) && skb->len < sizeof(*hdr) + 2)) {
		kfree_skb(skb);
		return s;
	}

	dlci = __get_dlci(hdr->addr);
	type = __get_type(hdr->ctrl);

	/* Trim FCS */
	skb->len--; skb->tail--;
	fcs = *(u8 *)skb_tail_pointer(skb);

	if (__check_fcs(skb->data, type, fcs)) {
		BT_ERR("bad checksum in packet");
		kfree_skb(skb);
		return s;
	}

	if (__test_ea(hdr->len))
		skb_pull(skb, 3);
	else
		skb_pull(skb, 4);

	switch (type) {
	case RFCOMM_SABM:
		if (__test_pf(hdr->ctrl))
			rfcomm_recv_sabm(s, dlci);
		break;

	case RFCOMM_DISC:
		if (__test_pf(hdr->ctrl))
			s = rfcomm_recv_disc(s, dlci);
		break;

	case RFCOMM_UA:
		if (__test_pf(hdr->ctrl))
			s = rfcomm_recv_ua(s, dlci);
		break;

	case RFCOMM_DM:
		s = rfcomm_recv_dm(s, dlci);
		break;

	case RFCOMM_UIH:
		if (dlci) {
			rfcomm_recv_data(s, dlci, __test_pf(hdr->ctrl), skb);
			return s;
		}
		rfcomm_recv_mcc(s, skb);
		break;

	default:
		BT_ERR("Unknown packet type 0x%02x", type);
		break;
	}
	kfree_skb(skb);
	return s;
}

/* ---- Connection and data processing ---- */

static void rfcomm_process_connect(struct rfcomm_session *s)
{
	struct rfcomm_dlc *d, *n;

	BT_DBG("session %p state %ld", s, s->state);

	list_for_each_entry_safe(d, n, &s->dlcs, list) {
		if (d->state == BT_CONFIG) {
			d->mtu = s->mtu;
			if (rfcomm_check_security(d)) {
				rfcomm_send_pn(s, 1, d);
			} else {
				set_bit(RFCOMM_AUTH_PENDING, &d->flags);
				rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
			}
		}
	}
}

/* Send data queued for the DLC.
 * Return number of frames left in the queue.
 */
static int rfcomm_process_tx(struct rfcomm_dlc *d)
{
	struct sk_buff *skb;
	int err;

	BT_DBG("dlc %p state %ld cfc %d rx_credits %d tx_credits %d",
			d, d->state, d->cfc, d->rx_credits, d->tx_credits);

	/* Send pending MSC */
	if (test_and_clear_bit(RFCOMM_MSC_PENDING, &d->flags))
		rfcomm_send_msc(d->session, 1, d->dlci, d->v24_sig);

	if (d->cfc) {
		/* CFC enabled.
		 * Give them some credits */
		if (!test_bit(RFCOMM_RX_THROTTLED, &d->flags) &&
				d->rx_credits <= (d->cfc >> 2)) {
			rfcomm_send_credits(d->session, d->addr, d->cfc - d->rx_credits);
			d->rx_credits = d->cfc;
		}
	} else {
		/* CFC disabled.
		 * Give ourselves some credits */
		d->tx_credits = 5;
	}

	if (test_bit(RFCOMM_TX_THROTTLED, &d->flags))
		return skb_queue_len(&d->tx_queue);

	while (d->tx_credits && (skb = skb_dequeue(&d->tx_queue))) {
		err = rfcomm_send_frame(d->session, skb->data, skb->len);
		if (err < 0) {
			skb_queue_head(&d->tx_queue, skb);
			break;
		}
		kfree_skb(skb);
		d->tx_credits--;
	}

	if (d->cfc && !d->tx_credits) {
		/* We're out of TX credits.
		 * Set TX_THROTTLED flag to avoid unnesary wakeups by dlc_send. */
		set_bit(RFCOMM_TX_THROTTLED, &d->flags);
	}

	return skb_queue_len(&d->tx_queue);
}

static void rfcomm_process_dlcs(struct rfcomm_session *s)
{
	struct rfcomm_dlc *d, *n;

	BT_DBG("session %p state %ld", s, s->state);

	list_for_each_entry_safe(d, n, &s->dlcs, list) {
		if (test_bit(RFCOMM_TIMED_OUT, &d->flags)) {
			__rfcomm_dlc_close(d, ETIMEDOUT);
			continue;
		}

		if (test_bit(RFCOMM_ENC_DROP, &d->flags)) {
			__rfcomm_dlc_close(d, ECONNREFUSED);
			continue;
		}

		if (test_and_clear_bit(RFCOMM_AUTH_ACCEPT, &d->flags)) {
			rfcomm_dlc_clear_timer(d);
			if (d->out) {
				rfcomm_send_pn(s, 1, d);
				rfcomm_dlc_set_timer(d, RFCOMM_CONN_TIMEOUT);
			} else {
				if (d->defer_setup) {
					set_bit(RFCOMM_DEFER_SETUP, &d->flags);
					rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);

					rfcomm_dlc_lock(d);
					d->state = BT_CONNECT2;
					d->state_change(d, 0);
					rfcomm_dlc_unlock(d);
				} else
					__rfcomm_dlc_accept(d);
			}
			continue;
		} else if (test_and_clear_bit(RFCOMM_AUTH_REJECT, &d->flags)) {
			rfcomm_dlc_clear_timer(d);
			if (!d->out)
				rfcomm_send_dm(s, d->dlci);
			else
				d->state = BT_CLOSED;
			__rfcomm_dlc_close(d, ECONNREFUSED);
			continue;
		}

		if (test_bit(RFCOMM_SEC_PENDING, &d->flags))
			continue;

		if (test_bit(RFCOMM_TX_THROTTLED, &s->flags))
			continue;

		if ((d->state == BT_CONNECTED || d->state == BT_DISCONN) &&
						d->mscex == RFCOMM_MSCEX_OK)
			rfcomm_process_tx(d);
	}
}

static struct rfcomm_session *rfcomm_process_rx(struct rfcomm_session *s)
{
	struct socket *sock = s->sock;
	struct sock *sk = sock->sk;
	struct sk_buff *skb;

	BT_DBG("session %p state %ld qlen %d", s, s->state, skb_queue_len(&sk->sk_receive_queue));

	/* Get data directly from socket receive queue without copying it. */
	while ((skb = skb_dequeue(&sk->sk_receive_queue))) {
		skb_orphan(skb);
		if (!skb_linearize(skb) && sk->sk_state != BT_CLOSED) {
			s = rfcomm_recv_frame(s, skb);
			if (!s)
				break;
		} else {
			kfree_skb(skb);
		}
	}

	if (s && (sk->sk_state == BT_CLOSED))
		s = rfcomm_session_close(s, sk->sk_err);

	return s;
}

static void rfcomm_accept_connection(struct rfcomm_session *s)
{
	struct socket *sock = s->sock, *nsock;
	int err;

	/* Fast check for a new connection.
	 * Avoids unnecessary socket allocations.
	 */
	if (list_empty(&bt_sk(sock->sk)->accept_q))
		return;

	BT_DBG("session %p", s);

	err = kernel_accept(sock, &nsock, O_NONBLOCK);
	if (err < 0)
		return;

	/* Set our callbacks */
	nsock->sk->sk_data_ready   = rfcomm_l2data_ready;
	nsock->sk->sk_state_change = rfcomm_l2state_change;

	s = rfcomm_session_add(nsock, BT_OPEN);
	if (s) {
		/* We should adjust MTU on incoming sessions.
		 * L2CAP MTU minus UIH header and FCS. */
		s->mtu = min(l2cap_pi(nsock->sk)->chan->omtu,
				l2cap_pi(nsock->sk)->chan->imtu) - 5;

		rfcomm_schedule();
	} else
		sock_release(nsock);
}

static struct rfcomm_session *rfcomm_check_connection(struct rfcomm_session *s)
{
	struct sock *sk = s->sock->sk;

	BT_DBG("%p state %ld", s, s->state);

	switch (sk->sk_state) {
	case BT_CONNECTED:
		s->state = BT_CONNECT;

		/* We can adjust MTU on outgoing sessions.
		 * L2CAP MTU minus UIH header and FCS. */
		s->mtu = min(l2cap_pi(sk)->chan->omtu, l2cap_pi(sk)->chan->imtu) - 5;

		rfcomm_send_sabm(s, 0);
		break;

	case BT_CLOSED:
		s = rfcomm_session_close(s, sk->sk_err);
		break;
	}
	return s;
}

static void rfcomm_process_sessions(void)
{
	struct rfcomm_session *s, *n;

	rfcomm_lock();

	list_for_each_entry_safe(s, n, &session_list, list) {
		if (test_and_clear_bit(RFCOMM_TIMED_OUT, &s->flags)) {
			s->state = BT_DISCONN;
			rfcomm_send_disc(s, 0);
			continue;
		}

		switch (s->state) {
		case BT_LISTEN:
			rfcomm_accept_connection(s);
			continue;

		case BT_BOUND:
			s = rfcomm_check_connection(s);
			break;

		default:
			s = rfcomm_process_rx(s);
			break;
		}

		if (s)
			rfcomm_process_dlcs(s);
	}

	rfcomm_unlock();
}

static int rfcomm_add_listener(bdaddr_t *ba)
{
	struct sockaddr_l2 addr;
	struct socket *sock;
	struct sock *sk;
	struct rfcomm_session *s;
	int    err = 0;

	/* Create socket */
	err = rfcomm_l2sock_create(&sock);
	if (err < 0) {
		BT_ERR("Create socket failed %d", err);
		return err;
	}

	/* Bind socket */
	bacpy(&addr.l2_bdaddr, ba);
	addr.l2_family = AF_BLUETOOTH;
	addr.l2_psm    = cpu_to_le16(L2CAP_PSM_RFCOMM);
	addr.l2_cid    = 0;
	addr.l2_bdaddr_type = BDADDR_BREDR;
	err = kernel_bind(sock, (struct sockaddr_unsized *)&addr, sizeof(addr));
	if (err < 0) {
		BT_ERR("Bind failed %d", err);
		goto failed;
	}

	/* Set L2CAP options */
	sk = sock->sk;
	lock_sock(sk);
	/* Set MTU to 0 so L2CAP can auto select the MTU */
	l2cap_pi(sk)->chan->imtu = 0;
	release_sock(sk);

	/* Start listening on the socket */
	err = kernel_listen(sock, 10);
	if (err) {
		BT_ERR("Listen failed %d", err);
		goto failed;
	}

	/* Add listening session */
	s = rfcomm_session_add(sock, BT_LISTEN);
	if (!s) {
		err = -ENOMEM;
		goto failed;
	}

	return 0;
failed:
	sock_release(sock);
	return err;
}

static void rfcomm_kill_listener(void)
{
	struct rfcomm_session *s, *n;

	BT_DBG("");

	rfcomm_lock();
	list_for_each_entry_safe(s, n, &session_list, list)
		rfcomm_session_del(s);
	rfcomm_unlock();
}

static int rfcomm_run(void *unused)
{
	DEFINE_WAIT_FUNC(wait, woken_wake_function);
	BT_DBG("");

	set_user_nice(current, -10);

	rfcomm_add_listener(BDADDR_ANY);

	add_wait_queue(&rfcomm_wq, &wait);
	while (!kthread_should_stop()) {

		/* Process stuff */
		rfcomm_process_sessions();

		wait_woken(&wait, TASK_INTERRUPTIBLE, MAX_SCHEDULE_TIMEOUT);
	}
	remove_wait_queue(&rfcomm_wq, &wait);

	rfcomm_kill_listener();

	return 0;
}

static void rfcomm_security_cfm(struct hci_conn *conn, u8 status, u8 encrypt)
{
	struct rfcomm_session *s;
	struct rfcomm_dlc *d, *n;

	BT_DBG("conn %p status 0x%02x encrypt 0x%02x", conn, status, encrypt);

	rfcomm_lock();

	s = rfcomm_session_get(&conn->hdev->bdaddr, &conn->dst);
	if (!s) {
		rfcomm_unlock();
		return;
	}

	list_for_each_entry_safe(d, n, &s->dlcs, list) {
		if (test_and_clear_bit(RFCOMM_SEC_PENDING, &d->flags)) {
			rfcomm_dlc_clear_timer(d);
			if (status || encrypt == 0x00) {
				set_bit(RFCOMM_ENC_DROP, &d->flags);
				continue;
			}
		}

		if (d->state == BT_CONNECTED && !status && encrypt == 0x00) {
			if (d->sec_level == BT_SECURITY_MEDIUM) {
				set_bit(RFCOMM_SEC_PENDING, &d->flags);
				rfcomm_dlc_set_timer(d, RFCOMM_AUTH_TIMEOUT);
				continue;
			} else if (d->sec_level == BT_SECURITY_HIGH ||
				   d->sec_level == BT_SECURITY_FIPS) {
				set_bit(RFCOMM_ENC_DROP, &d->flags);
				continue;
			}
		}

		if (!test_and_clear_bit(RFCOMM_AUTH_PENDING, &d->flags))
			continue;

		if (!status && hci_conn_check_secure(conn, d->sec_level))
			set_bit(RFCOMM_AUTH_ACCEPT, &d->flags);
		else
			set_bit(RFCOMM_AUTH_REJECT, &d->flags);
	}

	rfcomm_unlock();

	rfcomm_schedule();
}

static struct hci_cb rfcomm_cb = {
	.name		= "RFCOMM",
	.security_cfm	= rfcomm_security_cfm
};

static int rfcomm_dlc_debugfs_show(struct seq_file *f, void *x)
{
	struct rfcomm_session *s;

	rfcomm_lock();

	list_for_each_entry(s, &session_list, list) {
		struct l2cap_chan *chan = l2cap_pi(s->sock->sk)->chan;
		struct rfcomm_dlc *d;
		list_for_each_entry(d, &s->dlcs, list) {
			seq_printf(f, "%pMR %pMR %ld %d %d %d %d\n",
				   &chan->src, &chan->dst,
				   d->state, d->dlci, d->mtu,
				   d->rx_credits, d->tx_credits);
		}
	}

	rfcomm_unlock();

	return 0;
}

DEFINE_SHOW_ATTRIBUTE(rfcomm_dlc_debugfs);

static struct dentry *rfcomm_dlc_debugfs;

/* ---- Initialization ---- */
static int __init rfcomm_init(void)
{
	int err;

	hci_register_cb(&rfcomm_cb);

	rfcomm_thread = kthread_run(rfcomm_run, NULL, "krfcommd");
	if (IS_ERR(rfcomm_thread)) {
		err = PTR_ERR(rfcomm_thread);
		goto unregister;
	}

	err = rfcomm_init_ttys();
	if (err < 0)
		goto stop;

	err = rfcomm_init_sockets();
	if (err < 0)
		goto cleanup;

	BT_INFO("RFCOMM ver %s", VERSION);

	if (IS_ERR_OR_NULL(bt_debugfs))
		return 0;

	rfcomm_dlc_debugfs = debugfs_create_file("rfcomm_dlc", 0444,
						 bt_debugfs, NULL,
						 &rfcomm_dlc_debugfs_fops);

	return 0;

cleanup:
	rfcomm_cleanup_ttys();

stop:
	kthread_stop(rfcomm_thread);

unregister:
	hci_unregister_cb(&rfcomm_cb);

	return err;
}

static void __exit rfcomm_exit(void)
{
	debugfs_remove(rfcomm_dlc_debugfs);

	hci_unregister_cb(&rfcomm_cb);

	kthread_stop(rfcomm_thread);

	rfcomm_cleanup_ttys();

	rfcomm_cleanup_sockets();
}

module_init(rfcomm_init);
module_exit(rfcomm_exit);

module_param(disable_cfc, bool, 0644);
MODULE_PARM_DESC(disable_cfc, "Disable credit based flow control");

module_param(channel_mtu, int, 0644);
MODULE_PARM_DESC(channel_mtu, "Default MTU for the RFCOMM channel");

module_param(l2cap_ertm, bool, 0644);
MODULE_PARM_DESC(l2cap_ertm, "Use L2CAP ERTM mode for connection");

MODULE_AUTHOR("Marcel Holtmann <marcel@holtmann.org>");
MODULE_DESCRIPTION("Bluetooth RFCOMM ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS("bt-proto-3");