x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 1109 insertions, 0 deletions

diff --git a/net/bluetooth/rfcomm/sock.c b/net/bluetooth/rfcomm/sock.c
new file mode 100644
index 000000000..958081adb
--- /dev/null
+++ b/net/bluetooth/rfcomm/sock.c
@@ -0,0 +1,1109 @@
+// 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.
+*/
+
+/*
+ * RFCOMM sockets.
+ */
+#include <linux/compat.h>
+#include <linux/export.h>
+#include <linux/debugfs.h>
+#include <linux/sched/signal.h>
+#include <linux/uio.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+#include <net/bluetooth/l2cap.h>
+#include <net/bluetooth/rfcomm.h>
+
+static const struct proto_ops rfcomm_sock_ops;
+
+static struct bt_sock_list rfcomm_sk_list = {
+	.lock = __RW_LOCK_UNLOCKED(rfcomm_sk_list.lock)
+};
+
+static void rfcomm_sock_close(struct sock *sk);
+static void rfcomm_sock_kill(struct sock *sk);
+
+/* ---- DLC callbacks ----
+ *
+ * called under rfcomm_dlc_lock()
+ */
+static void rfcomm_sk_data_ready(struct rfcomm_dlc *d, struct sk_buff *skb)
+{
+	struct sock *sk = d->owner;
+	if (!sk)
+		return;
+
+	atomic_add(skb->len, &sk->sk_rmem_alloc);
+	skb_queue_tail(&sk->sk_receive_queue, skb);
+	sk->sk_data_ready(sk);
+
+	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)
+		rfcomm_dlc_throttle(d);
+}
+
+static void rfcomm_sk_state_change(struct rfcomm_dlc *d, int err)
+	__must_hold(&d->lock)
+{
+	struct sock *sk = d->owner, *parent;
+
+	if (!sk)
+		return;
+
+	BT_DBG("dlc %p state %ld err %d", d, d->state, err);
+
+	lock_sock(sk);
+
+	if (err)
+		sk->sk_err = err;
+
+	sk->sk_state = d->state;
+
+	parent = bt_sk(sk)->parent;
+	if (parent) {
+		if (d->state == BT_CLOSED) {
+			sock_set_flag(sk, SOCK_ZAPPED);
+			bt_accept_unlink(sk);
+		}
+		parent->sk_data_ready(parent);
+	} else {
+		if (d->state == BT_CONNECTED)
+			rfcomm_session_getaddr(d->session,
+					       &rfcomm_pi(sk)->src, NULL);
+		sk->sk_state_change(sk);
+	}
+
+	release_sock(sk);
+
+	if (parent && sock_flag(sk, SOCK_ZAPPED)) {
+		/* We have to drop DLC lock here, otherwise
+		 * rfcomm_sock_destruct() will dead lock. */
+		rfcomm_dlc_unlock(d);
+		rfcomm_sock_kill(sk);
+		rfcomm_dlc_lock(d);
+	}
+}
+
+/* ---- Socket functions ---- */
+static struct sock *__rfcomm_get_listen_sock_by_addr(u8 channel, bdaddr_t *src)
+{
+	struct sock *sk = NULL;
+
+	sk_for_each(sk, &rfcomm_sk_list.head) {
+		if (rfcomm_pi(sk)->channel != channel)
+			continue;
+
+		if (bacmp(&rfcomm_pi(sk)->src, src))
+			continue;
+
+		if (sk->sk_state == BT_BOUND || sk->sk_state == BT_LISTEN)
+			break;
+	}
+
+	return sk ? sk : NULL;
+}
+
+/* Find socket with channel and source bdaddr.
+ * Returns closest match with an extra reference held.
+ */
+static struct sock *rfcomm_get_sock_by_channel(int state, u8 channel, bdaddr_t *src)
+{
+	struct sock *sk = NULL, *sk1 = NULL;
+
+	read_lock(&rfcomm_sk_list.lock);
+
+	sk_for_each(sk, &rfcomm_sk_list.head) {
+		if (state && sk->sk_state != state)
+			continue;
+
+		if (rfcomm_pi(sk)->channel == channel) {
+			/* Exact match. */
+			if (!bacmp(&rfcomm_pi(sk)->src, src)) {
+				sock_hold(sk);
+				break;
+			}
+
+			/* Closest match */
+			if (!bacmp(&rfcomm_pi(sk)->src, BDADDR_ANY)) {
+				if (sk1)
+					sock_put(sk1);
+
+				sk1 = sk;
+				sock_hold(sk1);
+			}
+		}
+	}
+
+	if (sk && sk1)
+		sock_put(sk1);
+
+	read_unlock(&rfcomm_sk_list.lock);
+
+	return sk ? sk : sk1;
+}
+
+static void rfcomm_sock_destruct(struct sock *sk)
+{
+	struct rfcomm_dlc *d = rfcomm_pi(sk)->dlc;
+
+	BT_DBG("sk %p dlc %p", sk, d);
+
+	skb_queue_purge(&sk->sk_receive_queue);
+	skb_queue_purge(&sk->sk_write_queue);
+
+	rfcomm_dlc_lock(d);
+	rfcomm_pi(sk)->dlc = NULL;
+
+	/* Detach DLC if it's owned by this socket */
+	if (d->owner == sk)
+		d->owner = NULL;
+	rfcomm_dlc_unlock(d);
+
+	rfcomm_dlc_put(d);
+}
+
+static void rfcomm_sock_cleanup_listen(struct sock *parent)
+{
+	struct sock *sk;
+
+	BT_DBG("parent %p", parent);
+
+	/* Close not yet accepted dlcs */
+	while ((sk = bt_accept_dequeue(parent, NULL))) {
+		rfcomm_sock_close(sk);
+		rfcomm_sock_kill(sk);
+		/* Drop the reference handed back by bt_accept_dequeue(). */
+		sock_put(sk);
+	}
+
+	parent->sk_state  = BT_CLOSED;
+	sock_set_flag(parent, SOCK_ZAPPED);
+}
+
+/* Kill socket (only if zapped and orphan)
+ * Must be called on unlocked socket.
+ */
+static void rfcomm_sock_kill(struct sock *sk)
+{
+	if (!sock_flag(sk, SOCK_ZAPPED) || sk->sk_socket)
+		return;
+
+	BT_DBG("sk %p state %d refcnt %d", sk, sk->sk_state, refcount_read(&sk->sk_refcnt));
+
+	/* Kill poor orphan */
+	bt_sock_unlink(&rfcomm_sk_list, sk);
+	sock_set_flag(sk, SOCK_DEAD);
+	sock_put(sk);
+}
+
+static void __rfcomm_sock_close(struct sock *sk)
+{
+	struct rfcomm_dlc *d = rfcomm_pi(sk)->dlc;
+
+	BT_DBG("sk %p state %d socket %p", sk, sk->sk_state, sk->sk_socket);
+
+	switch (sk->sk_state) {
+	case BT_LISTEN:
+		rfcomm_sock_cleanup_listen(sk);
+		break;
+
+	case BT_CONNECT:
+	case BT_CONNECT2:
+	case BT_CONFIG:
+	case BT_CONNECTED:
+		rfcomm_dlc_close(d, 0);
+		fallthrough;
+
+	default:
+		sock_set_flag(sk, SOCK_ZAPPED);
+		break;
+	}
+}
+
+/* Close socket.
+ * Must be called on unlocked socket.
+ */
+static void rfcomm_sock_close(struct sock *sk)
+{
+	lock_sock(sk);
+	__rfcomm_sock_close(sk);
+	release_sock(sk);
+}
+
+static void rfcomm_sock_init(struct sock *sk, struct sock *parent)
+{
+	struct rfcomm_pinfo *pi = rfcomm_pi(sk);
+
+	BT_DBG("sk %p", sk);
+
+	if (parent) {
+		sk->sk_type = parent->sk_type;
+		pi->dlc->defer_setup = test_bit(BT_SK_DEFER_SETUP,
+						&bt_sk(parent)->flags);
+
+		pi->sec_level = rfcomm_pi(parent)->sec_level;
+		pi->role_switch = rfcomm_pi(parent)->role_switch;
+
+		security_sk_clone(parent, sk);
+	} else {
+		pi->dlc->defer_setup = 0;
+
+		pi->sec_level = BT_SECURITY_LOW;
+		pi->role_switch = 0;
+	}
+
+	pi->dlc->sec_level = pi->sec_level;
+	pi->dlc->role_switch = pi->role_switch;
+}
+
+static struct proto rfcomm_proto = {
+	.name		= "RFCOMM",
+	.owner		= THIS_MODULE,
+	.obj_size	= sizeof(struct rfcomm_pinfo)
+};
+
+static struct sock *rfcomm_sock_alloc(struct net *net, struct socket *sock,
+				      int proto, gfp_t prio, int kern)
+{
+	struct rfcomm_dlc *d;
+	struct sock *sk;
+
+	d = rfcomm_dlc_alloc(prio);
+	if (!d)
+		return NULL;
+
+	sk = bt_sock_alloc(net, sock, &rfcomm_proto, proto, prio, kern);
+	if (!sk) {
+		rfcomm_dlc_free(d);
+		return NULL;
+	}
+
+	d->data_ready   = rfcomm_sk_data_ready;
+	d->state_change = rfcomm_sk_state_change;
+
+	rfcomm_pi(sk)->dlc = d;
+	d->owner = sk;
+
+	sk->sk_destruct = rfcomm_sock_destruct;
+	sk->sk_sndtimeo = RFCOMM_CONN_TIMEOUT;
+
+	sk->sk_sndbuf = RFCOMM_MAX_CREDITS * RFCOMM_DEFAULT_MTU * 10;
+	sk->sk_rcvbuf = RFCOMM_MAX_CREDITS * RFCOMM_DEFAULT_MTU * 10;
+
+	bt_sock_link(&rfcomm_sk_list, sk);
+
+	BT_DBG("sk %p", sk);
+	return sk;
+}
+
+static int rfcomm_sock_create(struct net *net, struct socket *sock,
+			      int protocol, int kern)
+{
+	struct sock *sk;
+
+	BT_DBG("sock %p", sock);
+
+	sock->state = SS_UNCONNECTED;
+
+	if (sock->type != SOCK_STREAM && sock->type != SOCK_RAW)
+		return -ESOCKTNOSUPPORT;
+
+	sock->ops = &rfcomm_sock_ops;
+
+	sk = rfcomm_sock_alloc(net, sock, protocol, GFP_ATOMIC, kern);
+	if (!sk)
+		return -ENOMEM;
+
+	rfcomm_sock_init(sk, NULL);
+	return 0;
+}
+
+static int rfcomm_sock_bind(struct socket *sock, struct sockaddr_unsized *addr, int addr_len)
+{
+	struct sockaddr_rc sa;
+	struct sock *sk = sock->sk;
+	int len, err = 0;
+
+	if (!addr || addr_len < offsetofend(struct sockaddr, sa_family) ||
+	    addr->sa_family != AF_BLUETOOTH)
+		return -EINVAL;
+
+	memset(&sa, 0, sizeof(sa));
+	len = min_t(unsigned int, sizeof(sa), addr_len);
+	memcpy(&sa, addr, len);
+
+	BT_DBG("sk %p %pMR", sk, &sa.rc_bdaddr);
+
+	lock_sock(sk);
+
+	if (sk->sk_state != BT_OPEN) {
+		err = -EBADFD;
+		goto done;
+	}
+
+	if (sk->sk_type != SOCK_STREAM) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	write_lock(&rfcomm_sk_list.lock);
+
+	if (sa.rc_channel &&
+	    __rfcomm_get_listen_sock_by_addr(sa.rc_channel, &sa.rc_bdaddr)) {
+		err = -EADDRINUSE;
+	} else {
+		/* Save source address */
+		bacpy(&rfcomm_pi(sk)->src, &sa.rc_bdaddr);
+		rfcomm_pi(sk)->channel = sa.rc_channel;
+		sk->sk_state = BT_BOUND;
+	}
+
+	write_unlock(&rfcomm_sk_list.lock);
+
+done:
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_connect(struct socket *sock, struct sockaddr_unsized *addr,
+			       int alen, int flags)
+{
+	struct sockaddr_rc *sa = (struct sockaddr_rc *) addr;
+	struct sock *sk = sock->sk;
+	struct rfcomm_dlc *d = rfcomm_pi(sk)->dlc;
+	int err = 0;
+
+	BT_DBG("sk %p", sk);
+
+	if (alen < sizeof(struct sockaddr_rc) ||
+	    addr->sa_family != AF_BLUETOOTH)
+		return -EINVAL;
+
+	sock_hold(sk);
+	lock_sock(sk);
+
+	if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) {
+		err = -EBADFD;
+		goto done;
+	}
+
+	if (sk->sk_type != SOCK_STREAM) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	sk->sk_state = BT_CONNECT;
+	bacpy(&rfcomm_pi(sk)->dst, &sa->rc_bdaddr);
+	rfcomm_pi(sk)->channel = sa->rc_channel;
+
+	d->sec_level = rfcomm_pi(sk)->sec_level;
+	d->role_switch = rfcomm_pi(sk)->role_switch;
+
+	/* Drop sock lock to avoid potential deadlock with the RFCOMM lock */
+	release_sock(sk);
+	err = rfcomm_dlc_open(d, &rfcomm_pi(sk)->src, &sa->rc_bdaddr,
+			      sa->rc_channel);
+	lock_sock(sk);
+	if (!err && !sock_flag(sk, SOCK_ZAPPED))
+		err = bt_sock_wait_state(sk, BT_CONNECTED,
+				sock_sndtimeo(sk, flags & O_NONBLOCK));
+
+done:
+	release_sock(sk);
+	sock_put(sk);
+	return err;
+}
+
+static int rfcomm_sock_listen(struct socket *sock, int backlog)
+{
+	struct sock *sk = sock->sk;
+	int err = 0;
+
+	BT_DBG("sk %p backlog %d", sk, backlog);
+
+	lock_sock(sk);
+
+	if (sk->sk_state != BT_BOUND) {
+		err = -EBADFD;
+		goto done;
+	}
+
+	if (sk->sk_type != SOCK_STREAM) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	if (!rfcomm_pi(sk)->channel) {
+		bdaddr_t *src = &rfcomm_pi(sk)->src;
+		u8 channel;
+
+		err = -EINVAL;
+
+		write_lock(&rfcomm_sk_list.lock);
+
+		for (channel = 1; channel < 31; channel++)
+			if (!__rfcomm_get_listen_sock_by_addr(channel, src)) {
+				rfcomm_pi(sk)->channel = channel;
+				err = 0;
+				break;
+			}
+
+		write_unlock(&rfcomm_sk_list.lock);
+
+		if (err < 0)
+			goto done;
+	}
+
+	sk->sk_max_ack_backlog = backlog;
+	sk->sk_ack_backlog = 0;
+	sk->sk_state = BT_LISTEN;
+
+done:
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_accept(struct socket *sock, struct socket *newsock,
+			      struct proto_accept_arg *arg)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	struct sock *sk = sock->sk, *nsk;
+	long timeo;
+	int err = 0;
+
+	lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+
+	if (sk->sk_type != SOCK_STREAM) {
+		err = -EINVAL;
+		goto done;
+	}
+
+	timeo = sock_rcvtimeo(sk, arg->flags & O_NONBLOCK);
+
+	BT_DBG("sk %p timeo %ld", sk, timeo);
+
+	/* Wait for an incoming connection. (wake-one). */
+	add_wait_queue_exclusive(sk_sleep(sk), &wait);
+	while (1) {
+		if (sk->sk_state != BT_LISTEN) {
+			err = -EBADFD;
+			break;
+		}
+
+		nsk = bt_accept_dequeue(sk, newsock);
+		if (nsk) {
+			/* Drop the bridging ref from bt_accept_dequeue();
+			 * the grafted socket keeps nsk alive from here.
+			 */
+			sock_put(nsk);
+			break;
+		}
+
+		if (!timeo) {
+			err = -EAGAIN;
+			break;
+		}
+
+		if (signal_pending(current)) {
+			err = sock_intr_errno(timeo);
+			break;
+		}
+
+		release_sock(sk);
+
+		timeo = wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+
+		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+	}
+	remove_wait_queue(sk_sleep(sk), &wait);
+
+	if (err)
+		goto done;
+
+	newsock->state = SS_CONNECTED;
+
+	BT_DBG("new socket %p", nsk);
+
+done:
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_getname(struct socket *sock, struct sockaddr *addr, int peer)
+{
+	struct sockaddr_rc *sa = (struct sockaddr_rc *) addr;
+	struct sock *sk = sock->sk;
+
+	BT_DBG("sock %p, sk %p", sock, sk);
+
+	if (peer && sk->sk_state != BT_CONNECTED &&
+	    sk->sk_state != BT_CONNECT && sk->sk_state != BT_CONNECT2)
+		return -ENOTCONN;
+
+	memset(sa, 0, sizeof(*sa));
+	sa->rc_family  = AF_BLUETOOTH;
+	sa->rc_channel = rfcomm_pi(sk)->channel;
+	if (peer)
+		bacpy(&sa->rc_bdaddr, &rfcomm_pi(sk)->dst);
+	else
+		bacpy(&sa->rc_bdaddr, &rfcomm_pi(sk)->src);
+
+	return sizeof(struct sockaddr_rc);
+}
+
+static int rfcomm_sock_sendmsg(struct socket *sock, struct msghdr *msg,
+			       size_t len)
+{
+	struct sock *sk = sock->sk;
+	struct rfcomm_dlc *d = rfcomm_pi(sk)->dlc;
+	struct sk_buff *skb;
+	int sent;
+
+	if (test_bit(RFCOMM_DEFER_SETUP, &d->flags))
+		return -ENOTCONN;
+
+	if (msg->msg_flags & MSG_OOB)
+		return -EOPNOTSUPP;
+
+	if (sk->sk_shutdown & SEND_SHUTDOWN)
+		return -EPIPE;
+
+	BT_DBG("sock %p, sk %p", sock, sk);
+
+	lock_sock(sk);
+
+	sent = bt_sock_wait_ready(sk, msg->msg_flags);
+
+	release_sock(sk);
+
+	if (sent)
+		return sent;
+
+	skb = bt_skb_sendmmsg(sk, msg, len, d->mtu, RFCOMM_SKB_HEAD_RESERVE,
+			      RFCOMM_SKB_TAIL_RESERVE);
+	if (IS_ERR(skb))
+		return PTR_ERR(skb);
+
+	sent = rfcomm_dlc_send(d, skb);
+	if (sent < 0)
+		kfree_skb(skb);
+
+	return sent;
+}
+
+static int rfcomm_sock_recvmsg(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 len;
+
+	if (test_and_clear_bit(RFCOMM_DEFER_SETUP, &d->flags)) {
+		rfcomm_dlc_accept(d);
+		return 0;
+	}
+
+	len = bt_sock_stream_recvmsg(sock, msg, size, flags);
+
+	lock_sock(sk);
+	if (!(flags & MSG_PEEK) && len > 0)
+		atomic_sub(len, &sk->sk_rmem_alloc);
+
+	if (atomic_read(&sk->sk_rmem_alloc) <= (sk->sk_rcvbuf >> 2))
+		rfcomm_dlc_unthrottle(rfcomm_pi(sk)->dlc);
+	release_sock(sk);
+
+	return len;
+}
+
+static int rfcomm_sock_setsockopt_old(struct socket *sock, int optname,
+		sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = sock->sk;
+	int err = 0;
+	u32 opt;
+
+	BT_DBG("sk %p", sk);
+
+	lock_sock(sk);
+
+	switch (optname) {
+	case RFCOMM_LM:
+		err = copy_safe_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
+			break;
+
+		if (opt & RFCOMM_LM_FIPS) {
+			err = -EINVAL;
+			break;
+		}
+
+		if (opt & RFCOMM_LM_AUTH)
+			rfcomm_pi(sk)->sec_level = BT_SECURITY_LOW;
+		if (opt & RFCOMM_LM_ENCRYPT)
+			rfcomm_pi(sk)->sec_level = BT_SECURITY_MEDIUM;
+		if (opt & RFCOMM_LM_SECURE)
+			rfcomm_pi(sk)->sec_level = BT_SECURITY_HIGH;
+
+		rfcomm_pi(sk)->role_switch = (opt & RFCOMM_LM_MASTER);
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_setsockopt(struct socket *sock, int level, int optname,
+		sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = sock->sk;
+	struct bt_security sec;
+	int err = 0;
+	u32 opt;
+
+	BT_DBG("sk %p", sk);
+
+	if (level == SOL_RFCOMM)
+		return rfcomm_sock_setsockopt_old(sock, optname, optval, optlen);
+
+	if (level != SOL_BLUETOOTH)
+		return -ENOPROTOOPT;
+
+	lock_sock(sk);
+
+	switch (optname) {
+	case BT_SECURITY:
+		if (sk->sk_type != SOCK_STREAM) {
+			err = -EINVAL;
+			break;
+		}
+
+		sec.level = BT_SECURITY_LOW;
+
+		err = copy_safe_from_sockptr(&sec, sizeof(sec), optval, optlen);
+		if (err)
+			break;
+
+		if (sec.level > BT_SECURITY_HIGH) {
+			err = -EINVAL;
+			break;
+		}
+
+		rfcomm_pi(sk)->sec_level = sec.level;
+		break;
+
+	case BT_DEFER_SETUP:
+		if (sk->sk_state != BT_BOUND && sk->sk_state != BT_LISTEN) {
+			err = -EINVAL;
+			break;
+		}
+
+		err = copy_safe_from_sockptr(&opt, sizeof(opt), optval, optlen);
+		if (err)
+			break;
+
+		if (opt)
+			set_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags);
+		else
+			clear_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags);
+
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_getsockopt_old(struct socket *sock, int optname,
+				      sockopt_t *sopt)
+{
+	struct sock *sk = sock->sk;
+	struct sock *l2cap_sk;
+	struct l2cap_conn *conn;
+	struct rfcomm_conninfo cinfo;
+	int err = 0;
+	size_t len;
+	u32 opt;
+
+	BT_DBG("sk %p", sk);
+
+	len = sopt->optlen;
+
+	lock_sock(sk);
+
+	switch (optname) {
+	case RFCOMM_LM:
+		switch (rfcomm_pi(sk)->sec_level) {
+		case BT_SECURITY_LOW:
+			opt = RFCOMM_LM_AUTH;
+			break;
+		case BT_SECURITY_MEDIUM:
+			opt = RFCOMM_LM_AUTH | RFCOMM_LM_ENCRYPT;
+			break;
+		case BT_SECURITY_HIGH:
+			opt = RFCOMM_LM_AUTH | RFCOMM_LM_ENCRYPT |
+			      RFCOMM_LM_SECURE;
+			break;
+		case BT_SECURITY_FIPS:
+			opt = RFCOMM_LM_AUTH | RFCOMM_LM_ENCRYPT |
+			      RFCOMM_LM_SECURE | RFCOMM_LM_FIPS;
+			break;
+		default:
+			opt = 0;
+			break;
+		}
+
+		if (rfcomm_pi(sk)->role_switch)
+			opt |= RFCOMM_LM_MASTER;
+
+		if (copy_to_iter(&opt, sizeof(opt), &sopt->iter_out) !=
+		    sizeof(opt))
+			err = -EFAULT;
+
+		break;
+
+	case RFCOMM_CONNINFO:
+		if (sk->sk_state != BT_CONNECTED &&
+					!rfcomm_pi(sk)->dlc->defer_setup) {
+			err = -ENOTCONN;
+			break;
+		}
+
+		l2cap_sk = rfcomm_pi(sk)->dlc->session->sock->sk;
+		conn = l2cap_pi(l2cap_sk)->chan->conn;
+
+		memset(&cinfo, 0, sizeof(cinfo));
+		cinfo.hci_handle = conn->hcon->handle;
+		memcpy(cinfo.dev_class, conn->hcon->dev_class, 3);
+
+		len = min(len, sizeof(cinfo));
+		if (copy_to_iter(&cinfo, len, &sopt->iter_out) != len)
+			err = -EFAULT;
+
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_getsockopt(struct socket *sock, int level, int optname,
+				  sockopt_t *sopt)
+{
+	struct sock *sk = sock->sk;
+	struct bt_security sec;
+	int err = 0;
+	size_t len;
+	u32 opt;
+
+	BT_DBG("sk %p", sk);
+
+	if (level == SOL_RFCOMM)
+		return rfcomm_sock_getsockopt_old(sock, optname, sopt);
+
+	if (level != SOL_BLUETOOTH)
+		return -ENOPROTOOPT;
+
+	len = sopt->optlen;
+
+	lock_sock(sk);
+
+	switch (optname) {
+	case BT_SECURITY:
+		if (sk->sk_type != SOCK_STREAM) {
+			err = -EINVAL;
+			break;
+		}
+
+		sec.level = rfcomm_pi(sk)->sec_level;
+		sec.key_size = 0;
+
+		len = min(len, sizeof(sec));
+		if (copy_to_iter(&sec, len, &sopt->iter_out) != len)
+			err = -EFAULT;
+
+		break;
+
+	case BT_DEFER_SETUP:
+		if (sk->sk_state != BT_BOUND && sk->sk_state != BT_LISTEN) {
+			err = -EINVAL;
+			break;
+		}
+
+		opt = test_bit(BT_SK_DEFER_SETUP, &bt_sk(sk)->flags);
+		if (copy_to_iter(&opt, sizeof(opt), &sopt->iter_out) !=
+		    sizeof(opt))
+			err = -EFAULT;
+
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	struct sock *sk __maybe_unused = sock->sk;
+	int err;
+
+	BT_DBG("sk %p cmd %x arg %lx", sk, cmd, arg);
+
+	err = bt_sock_ioctl(sock, cmd, arg);
+
+	if (err == -ENOIOCTLCMD) {
+#ifdef CONFIG_BT_RFCOMM_TTY
+		err = rfcomm_dev_ioctl(sk, cmd, (void __user *) arg);
+#else
+		err = -EOPNOTSUPP;
+#endif
+	}
+
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+static int rfcomm_sock_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	return rfcomm_sock_ioctl(sock, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static int rfcomm_sock_shutdown(struct socket *sock, int how)
+{
+	struct sock *sk = sock->sk;
+	int err = 0;
+
+	BT_DBG("sock %p, sk %p", sock, sk);
+
+	if (!sk)
+		return 0;
+
+	lock_sock(sk);
+	if (!sk->sk_shutdown) {
+		sk->sk_shutdown = SHUTDOWN_MASK;
+
+		release_sock(sk);
+		__rfcomm_sock_close(sk);
+		lock_sock(sk);
+
+		if (sock_flag(sk, SOCK_LINGER) && sk->sk_lingertime &&
+		    !(current->flags & PF_EXITING))
+			err = bt_sock_wait_state(sk, BT_CLOSED, sk->sk_lingertime);
+	}
+	release_sock(sk);
+	return err;
+}
+
+static int rfcomm_sock_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	int err;
+
+	BT_DBG("sock %p, sk %p", sock, sk);
+
+	if (!sk)
+		return 0;
+
+	err = rfcomm_sock_shutdown(sock, 2);
+
+	sock_orphan(sk);
+	rfcomm_sock_kill(sk);
+	return err;
+}
+
+/* ---- RFCOMM core layer callbacks ----
+ *
+ * called under rfcomm_lock()
+ */
+int rfcomm_connect_ind(struct rfcomm_session *s, u8 channel, struct rfcomm_dlc **d)
+{
+	struct sock *sk, *parent;
+	bdaddr_t src, dst;
+	bool defer_setup = false;
+	int result = 0;
+
+	BT_DBG("session %p channel %d", s, channel);
+
+	rfcomm_session_getaddr(s, &src, &dst);
+
+	/* Check if we have socket listening on channel */
+	parent = rfcomm_get_sock_by_channel(BT_LISTEN, channel, &src);
+	if (!parent)
+		return 0;
+
+	lock_sock(parent);
+
+	if (parent->sk_state != BT_LISTEN)
+		goto done;
+
+	defer_setup = test_bit(BT_SK_DEFER_SETUP, &bt_sk(parent)->flags);
+
+	/* Check for backlog size */
+	if (sk_acceptq_is_full(parent)) {
+		BT_DBG("backlog full %d", parent->sk_ack_backlog);
+		goto done;
+	}
+
+	sk = rfcomm_sock_alloc(sock_net(parent), NULL, BTPROTO_RFCOMM, GFP_ATOMIC, 0);
+	if (!sk)
+		goto done;
+
+	bt_sock_reclassify_lock(sk, BTPROTO_RFCOMM);
+
+	rfcomm_sock_init(sk, parent);
+	bacpy(&rfcomm_pi(sk)->src, &src);
+	bacpy(&rfcomm_pi(sk)->dst, &dst);
+	rfcomm_pi(sk)->channel = channel;
+
+	sk->sk_state = BT_CONFIG;
+	bt_accept_enqueue(parent, sk, true);
+
+	/* Accept connection and return socket DLC */
+	*d = rfcomm_pi(sk)->dlc;
+	result = 1;
+
+done:
+	release_sock(parent);
+
+	if (defer_setup)
+		parent->sk_state_change(parent);
+
+	sock_put(parent);
+
+	return result;
+}
+
+static int rfcomm_sock_debugfs_show(struct seq_file *f, void *p)
+{
+	struct sock *sk;
+
+	read_lock(&rfcomm_sk_list.lock);
+
+	sk_for_each(sk, &rfcomm_sk_list.head) {
+		seq_printf(f, "%pMR %pMR %d %d\n",
+			   &rfcomm_pi(sk)->src, &rfcomm_pi(sk)->dst,
+			   sk->sk_state, rfcomm_pi(sk)->channel);
+	}
+
+	read_unlock(&rfcomm_sk_list.lock);
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(rfcomm_sock_debugfs);
+
+static struct dentry *rfcomm_sock_debugfs;
+
+static const struct proto_ops rfcomm_sock_ops = {
+	.family		= PF_BLUETOOTH,
+	.owner		= THIS_MODULE,
+	.release	= rfcomm_sock_release,
+	.bind		= rfcomm_sock_bind,
+	.connect	= rfcomm_sock_connect,
+	.listen		= rfcomm_sock_listen,
+	.accept		= rfcomm_sock_accept,
+	.getname	= rfcomm_sock_getname,
+	.sendmsg	= rfcomm_sock_sendmsg,
+	.recvmsg	= rfcomm_sock_recvmsg,
+	.shutdown	= rfcomm_sock_shutdown,
+	.setsockopt	= rfcomm_sock_setsockopt,
+	.getsockopt_iter = rfcomm_sock_getsockopt,
+	.ioctl		= rfcomm_sock_ioctl,
+	.gettstamp	= sock_gettstamp,
+	.poll		= bt_sock_poll,
+	.socketpair	= sock_no_socketpair,
+	.mmap		= sock_no_mmap,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= rfcomm_sock_compat_ioctl,
+#endif
+};
+
+static const struct net_proto_family rfcomm_sock_family_ops = {
+	.family		= PF_BLUETOOTH,
+	.owner		= THIS_MODULE,
+	.create		= rfcomm_sock_create
+};
+
+int __init rfcomm_init_sockets(void)
+{
+	int err;
+
+	BUILD_BUG_ON(sizeof(struct sockaddr_rc) > sizeof(struct sockaddr));
+
+	err = proto_register(&rfcomm_proto, 0);
+	if (err < 0)
+		return err;
+
+	err = bt_sock_register(BTPROTO_RFCOMM, &rfcomm_sock_family_ops);
+	if (err < 0) {
+		BT_ERR("RFCOMM socket layer registration failed");
+		goto error;
+	}
+
+	err = bt_procfs_init(&init_net, "rfcomm", &rfcomm_sk_list, NULL);
+	if (err < 0) {
+		BT_ERR("Failed to create RFCOMM proc file");
+		bt_sock_unregister(BTPROTO_RFCOMM);
+		goto error;
+	}
+
+	BT_INFO("RFCOMM socket layer initialized");
+
+	if (IS_ERR_OR_NULL(bt_debugfs))
+		return 0;
+
+	rfcomm_sock_debugfs = debugfs_create_file("rfcomm", 0444,
+						  bt_debugfs, NULL,
+						  &rfcomm_sock_debugfs_fops);
+
+	return 0;
+
+error:
+	proto_unregister(&rfcomm_proto);
+	return err;
+}
+
+void __exit rfcomm_cleanup_sockets(void)
+{
+	bt_procfs_cleanup(&init_net, "rfcomm");
+
+	debugfs_remove(rfcomm_sock_debugfs);
+
+	bt_sock_unregister(BTPROTO_RFCOMM);
+
+	proto_unregister(&rfcomm_proto);
+}