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, 1076 insertions, 0 deletions

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
new file mode 100644
index 000000000..5558d8a4d
--- /dev/null
+++ b/net/nfc/llcp_sock.c
@@ -0,0 +1,1076 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2011  Intel Corporation. All rights reserved.
+ */
+
+#define pr_fmt(fmt) "llcp: %s: " fmt, __func__
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/nfc.h>
+#include <linux/sched/signal.h>
+
+#include "nfc.h"
+#include "llcp.h"
+
+static int sock_wait_state(struct sock *sk, int state, unsigned long timeo)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	int err = 0;
+
+	pr_debug("sk %p", sk);
+
+	add_wait_queue(sk_sleep(sk), &wait);
+	set_current_state(TASK_INTERRUPTIBLE);
+
+	while (sk->sk_state != state) {
+		if (!timeo) {
+			err = -EINPROGRESS;
+			break;
+		}
+
+		if (signal_pending(current)) {
+			err = sock_intr_errno(timeo);
+			break;
+		}
+
+		release_sock(sk);
+		timeo = schedule_timeout(timeo);
+		lock_sock(sk);
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		err = sock_error(sk);
+		if (err)
+			break;
+	}
+
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(sk_sleep(sk), &wait);
+	return err;
+}
+
+static struct proto llcp_sock_proto = {
+	.name     = "NFC_LLCP",
+	.owner    = THIS_MODULE,
+	.obj_size = sizeof(struct nfc_llcp_sock),
+};
+
+static int llcp_sock_bind(struct socket *sock, struct sockaddr_unsized *addr, int alen)
+{
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	struct nfc_llcp_local *local;
+	struct nfc_dev *dev;
+	struct sockaddr_nfc_llcp llcp_addr;
+	int len, ret = 0;
+
+	if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
+	    addr->sa_family != AF_NFC)
+		return -EINVAL;
+
+	pr_debug("sk %p addr %p family %d\n", sk, addr, addr->sa_family);
+
+	memset(&llcp_addr, 0, sizeof(llcp_addr));
+	len = min_t(unsigned int, sizeof(llcp_addr), alen);
+	memcpy(&llcp_addr, addr, len);
+
+	/* This is going to be a listening socket, dsap must be 0 */
+	if (llcp_addr.dsap != 0)
+		return -EINVAL;
+
+	lock_sock(sk);
+
+	if (sk->sk_state != LLCP_CLOSED) {
+		ret = -EBADFD;
+		goto error;
+	}
+
+	dev = nfc_get_device(llcp_addr.dev_idx);
+	if (dev == NULL) {
+		ret = -ENODEV;
+		goto error;
+	}
+
+	local = nfc_llcp_find_local(dev);
+	if (local == NULL) {
+		ret = -ENODEV;
+		goto put_dev;
+	}
+
+	llcp_sock->dev = dev;
+	llcp_sock->local = local;
+	llcp_sock->nfc_protocol = llcp_addr.nfc_protocol;
+	llcp_sock->service_name_len = min_t(unsigned int,
+					    llcp_addr.service_name_len,
+					    NFC_LLCP_MAX_SERVICE_NAME);
+	llcp_sock->service_name = kmemdup(llcp_addr.service_name,
+					  llcp_sock->service_name_len,
+					  GFP_KERNEL);
+	if (!llcp_sock->service_name) {
+		ret = -ENOMEM;
+		goto sock_llcp_put_local;
+	}
+	llcp_sock->ssap = nfc_llcp_get_sdp_ssap(local, llcp_sock);
+	if (llcp_sock->ssap == LLCP_SAP_MAX) {
+		ret = -EADDRINUSE;
+		goto free_service_name;
+	}
+
+	llcp_sock->reserved_ssap = llcp_sock->ssap;
+
+	nfc_llcp_sock_link(&local->sockets, sk);
+
+	pr_debug("Socket bound to SAP %d\n", llcp_sock->ssap);
+
+	sk->sk_state = LLCP_BOUND;
+	nfc_put_device(dev);
+	release_sock(sk);
+
+	return 0;
+
+free_service_name:
+	kfree(llcp_sock->service_name);
+	llcp_sock->service_name = NULL;
+
+sock_llcp_put_local:
+	nfc_llcp_local_put(llcp_sock->local);
+	llcp_sock->local = NULL;
+	llcp_sock->dev = NULL;
+
+put_dev:
+	nfc_put_device(dev);
+
+error:
+	release_sock(sk);
+	return ret;
+}
+
+static int llcp_raw_sock_bind(struct socket *sock, struct sockaddr_unsized *addr,
+			      int alen)
+{
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	struct nfc_llcp_local *local;
+	struct nfc_dev *dev;
+	struct sockaddr_nfc_llcp llcp_addr;
+	int len, ret = 0;
+
+	if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
+	    addr->sa_family != AF_NFC)
+		return -EINVAL;
+
+	pr_debug("sk %p addr %p family %d\n", sk, addr, addr->sa_family);
+
+	memset(&llcp_addr, 0, sizeof(llcp_addr));
+	len = min_t(unsigned int, sizeof(llcp_addr), alen);
+	memcpy(&llcp_addr, addr, len);
+
+	lock_sock(sk);
+
+	if (sk->sk_state != LLCP_CLOSED) {
+		ret = -EBADFD;
+		goto error;
+	}
+
+	dev = nfc_get_device(llcp_addr.dev_idx);
+	if (dev == NULL) {
+		ret = -ENODEV;
+		goto error;
+	}
+
+	local = nfc_llcp_find_local(dev);
+	if (local == NULL) {
+		ret = -ENODEV;
+		goto put_dev;
+	}
+
+	llcp_sock->dev = dev;
+	llcp_sock->local = local;
+	llcp_sock->nfc_protocol = llcp_addr.nfc_protocol;
+
+	nfc_llcp_sock_link(&local->raw_sockets, sk);
+
+	sk->sk_state = LLCP_BOUND;
+
+put_dev:
+	nfc_put_device(dev);
+
+error:
+	release_sock(sk);
+	return ret;
+}
+
+static int llcp_sock_listen(struct socket *sock, int backlog)
+{
+	struct sock *sk = sock->sk;
+	int ret = 0;
+
+	pr_debug("sk %p backlog %d\n", sk, backlog);
+
+	lock_sock(sk);
+
+	if ((sock->type != SOCK_SEQPACKET && sock->type != SOCK_STREAM) ||
+	    sk->sk_state != LLCP_BOUND) {
+		ret = -EBADFD;
+		goto error;
+	}
+
+	sk->sk_max_ack_backlog = backlog;
+	sk->sk_ack_backlog = 0;
+
+	pr_debug("Socket listening\n");
+	sk->sk_state = LLCP_LISTEN;
+
+error:
+	release_sock(sk);
+
+	return ret;
+}
+
+static int nfc_llcp_setsockopt(struct socket *sock, int level, int optname,
+			       sockptr_t optval, unsigned int optlen)
+{
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	u32 opt;
+	int err = 0;
+
+	pr_debug("%p optname %d\n", sk, optname);
+
+	if (level != SOL_NFC)
+		return -ENOPROTOOPT;
+
+	lock_sock(sk);
+
+	switch (optname) {
+	case NFC_LLCP_RW:
+		if (sk->sk_state == LLCP_CONNECTED ||
+		    sk->sk_state == LLCP_BOUND ||
+		    sk->sk_state == LLCP_LISTEN) {
+			err = -EINVAL;
+			break;
+		}
+
+		err = copy_safe_from_sockptr(&opt, sizeof(opt),
+					     optval, optlen);
+		if (err)
+			break;
+
+		if (opt > LLCP_MAX_RW) {
+			err = -EINVAL;
+			break;
+		}
+
+		llcp_sock->rw = (u8) opt;
+
+		break;
+
+	case NFC_LLCP_MIUX:
+		if (sk->sk_state == LLCP_CONNECTED ||
+		    sk->sk_state == LLCP_BOUND ||
+		    sk->sk_state == LLCP_LISTEN) {
+			err = -EINVAL;
+			break;
+		}
+
+		err = copy_safe_from_sockptr(&opt, sizeof(opt),
+					     optval, optlen);
+		if (err)
+			break;
+
+		if (opt > LLCP_MAX_MIUX) {
+			err = -EINVAL;
+			break;
+		}
+
+		llcp_sock->miux = cpu_to_be16((u16) opt);
+
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	release_sock(sk);
+
+	pr_debug("%p rw %d miux %d\n", llcp_sock,
+		 llcp_sock->rw, llcp_sock->miux);
+
+	return err;
+}
+
+static int nfc_llcp_getsockopt(struct socket *sock, int level, int optname,
+			       char __user *optval, int __user *optlen)
+{
+	struct nfc_llcp_local *local;
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	int len, err = 0;
+	u16 miux, remote_miu;
+	u8 rw;
+
+	pr_debug("%p optname %d\n", sk, optname);
+
+	if (level != SOL_NFC)
+		return -ENOPROTOOPT;
+
+	if (get_user(len, optlen))
+		return -EFAULT;
+
+	if (len < 0)
+		return -EINVAL;
+
+	if (len < sizeof(u32))
+		return -EINVAL;
+
+	len = min_t(u32, len, sizeof(u32));
+
+	lock_sock(sk);
+
+	local = llcp_sock->local;
+	if (!local) {
+		release_sock(sk);
+		return -ENODEV;
+	}
+
+	switch (optname) {
+	case NFC_LLCP_RW:
+		rw = llcp_sock->rw > LLCP_MAX_RW ? local->rw : llcp_sock->rw;
+		if (put_user(rw, (u32 __user *) optval))
+			err = -EFAULT;
+
+		break;
+
+	case NFC_LLCP_MIUX:
+		miux = be16_to_cpu(llcp_sock->miux) > LLCP_MAX_MIUX ?
+			be16_to_cpu(local->miux) : be16_to_cpu(llcp_sock->miux);
+
+		if (put_user(miux, (u32 __user *) optval))
+			err = -EFAULT;
+
+		break;
+
+	case NFC_LLCP_REMOTE_MIU:
+		remote_miu = llcp_sock->remote_miu > LLCP_MAX_MIU ?
+				local->remote_miu : llcp_sock->remote_miu;
+
+		if (put_user(remote_miu, (u32 __user *) optval))
+			err = -EFAULT;
+
+		break;
+
+	case NFC_LLCP_REMOTE_LTO:
+		if (put_user(local->remote_lto / 10, (u32 __user *) optval))
+			err = -EFAULT;
+
+		break;
+
+	case NFC_LLCP_REMOTE_RW:
+		if (put_user(llcp_sock->remote_rw, (u32 __user *) optval))
+			err = -EFAULT;
+
+		break;
+
+	default:
+		err = -ENOPROTOOPT;
+		break;
+	}
+
+	release_sock(sk);
+
+	if (put_user(len, optlen))
+		return -EFAULT;
+
+	return err;
+}
+
+void nfc_llcp_accept_unlink(struct sock *sk)
+{
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+
+	pr_debug("state %d\n", sk->sk_state);
+
+	list_del_init(&llcp_sock->accept_queue);
+	sk_acceptq_removed(llcp_sock->parent);
+	llcp_sock->parent = NULL;
+
+	sock_put(sk);
+}
+
+void nfc_llcp_accept_enqueue(struct sock *parent, struct sock *sk)
+{
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	struct nfc_llcp_sock *llcp_sock_parent = nfc_llcp_sock(parent);
+
+	/* Lock will be free from unlink */
+	sock_hold(sk);
+
+	list_add_tail(&llcp_sock->accept_queue,
+		      &llcp_sock_parent->accept_queue);
+	llcp_sock->parent = parent;
+	sk_acceptq_added(parent);
+}
+
+struct sock *nfc_llcp_accept_dequeue(struct sock *parent,
+				     struct socket *newsock)
+{
+	struct nfc_llcp_sock *lsk, *n, *llcp_parent;
+	struct sock *sk;
+
+	llcp_parent = nfc_llcp_sock(parent);
+
+	list_for_each_entry_safe(lsk, n, &llcp_parent->accept_queue,
+				 accept_queue) {
+		sk = &lsk->sk;
+		lock_sock(sk);
+
+		if (sk->sk_state == LLCP_CLOSED) {
+			release_sock(sk);
+			nfc_llcp_accept_unlink(sk);
+			continue;
+		}
+
+		if (sk->sk_state == LLCP_CONNECTED || !newsock) {
+			list_del_init(&lsk->accept_queue);
+			sock_put(sk);
+
+			if (newsock)
+				sock_graft(sk, newsock);
+
+			release_sock(sk);
+
+			pr_debug("Returning sk state %d\n", sk->sk_state);
+
+			sk_acceptq_removed(parent);
+
+			return sk;
+		}
+
+		release_sock(sk);
+	}
+
+	return NULL;
+}
+
+static int llcp_sock_accept(struct socket *sock, struct socket *newsock,
+			    struct proto_accept_arg *arg)
+{
+	DECLARE_WAITQUEUE(wait, current);
+	struct sock *sk = sock->sk, *new_sk;
+	long timeo;
+	int ret = 0;
+
+	pr_debug("parent %p\n", sk);
+
+	lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+
+	if (sk->sk_state != LLCP_LISTEN) {
+		ret = -EBADFD;
+		goto error;
+	}
+
+	timeo = sock_rcvtimeo(sk, arg->flags & O_NONBLOCK);
+
+	/* Wait for an incoming connection. */
+	add_wait_queue_exclusive(sk_sleep(sk), &wait);
+	while (!(new_sk = nfc_llcp_accept_dequeue(sk, newsock))) {
+		set_current_state(TASK_INTERRUPTIBLE);
+
+		if (!timeo) {
+			ret = -EAGAIN;
+			break;
+		}
+
+		if (signal_pending(current)) {
+			ret = sock_intr_errno(timeo);
+			break;
+		}
+
+		release_sock(sk);
+		timeo = schedule_timeout(timeo);
+		lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
+	}
+	__set_current_state(TASK_RUNNING);
+	remove_wait_queue(sk_sleep(sk), &wait);
+
+	if (ret)
+		goto error;
+
+	newsock->state = SS_CONNECTED;
+
+	pr_debug("new socket %p\n", new_sk);
+
+error:
+	release_sock(sk);
+
+	return ret;
+}
+
+static int llcp_sock_getname(struct socket *sock, struct sockaddr *uaddr,
+			     int peer)
+{
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	DECLARE_SOCKADDR(struct sockaddr_nfc_llcp *, llcp_addr, uaddr);
+
+	if (llcp_sock == NULL || llcp_sock->dev == NULL)
+		return -EBADFD;
+
+	pr_debug("%p %d %d %d\n", sk, llcp_sock->target_idx,
+		 llcp_sock->dsap, llcp_sock->ssap);
+
+	memset(llcp_addr, 0, sizeof(*llcp_addr));
+
+	lock_sock(sk);
+	if (!llcp_sock->dev) {
+		release_sock(sk);
+		return -EBADFD;
+	}
+	llcp_addr->sa_family = AF_NFC;
+	llcp_addr->dev_idx = llcp_sock->dev->idx;
+	llcp_addr->target_idx = llcp_sock->target_idx;
+	llcp_addr->nfc_protocol = llcp_sock->nfc_protocol;
+	llcp_addr->dsap = llcp_sock->dsap;
+	llcp_addr->ssap = llcp_sock->ssap;
+	llcp_addr->service_name_len = llcp_sock->service_name_len;
+	memcpy(llcp_addr->service_name, llcp_sock->service_name,
+	       llcp_addr->service_name_len);
+	release_sock(sk);
+
+	return sizeof(struct sockaddr_nfc_llcp);
+}
+
+static inline __poll_t llcp_accept_poll(struct sock *parent)
+{
+	struct nfc_llcp_sock *llcp_sock, *parent_sock;
+	struct sock *sk;
+
+	parent_sock = nfc_llcp_sock(parent);
+
+	list_for_each_entry(llcp_sock, &parent_sock->accept_queue,
+			    accept_queue) {
+		sk = &llcp_sock->sk;
+
+		if (sk->sk_state == LLCP_CONNECTED)
+			return EPOLLIN | EPOLLRDNORM;
+	}
+
+	return 0;
+}
+
+static __poll_t llcp_sock_poll(struct file *file, struct socket *sock,
+				   poll_table *wait)
+{
+	struct sock *sk = sock->sk;
+	__poll_t mask = 0;
+
+	pr_debug("%p\n", sk);
+
+	sock_poll_wait(file, sock, wait);
+
+	if (sk->sk_state == LLCP_LISTEN)
+		return llcp_accept_poll(sk);
+
+	if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
+		mask |= EPOLLERR |
+			(sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0);
+
+	if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	if (sk->sk_state == LLCP_CLOSED)
+		mask |= EPOLLHUP;
+
+	if (sk->sk_shutdown & RCV_SHUTDOWN)
+		mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
+
+	if (sk->sk_shutdown == SHUTDOWN_MASK)
+		mask |= EPOLLHUP;
+
+	if (sock_writeable(sk) && sk->sk_state == LLCP_CONNECTED)
+		mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
+	else
+		sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+
+	pr_debug("mask 0x%x\n", mask);
+
+	return mask;
+}
+
+static int llcp_sock_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_local *local;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	int err = 0;
+
+	if (!sk)
+		return 0;
+
+	pr_debug("%p\n", sk);
+
+	local = llcp_sock->local;
+	if (local == NULL) {
+		err = -ENODEV;
+		goto out;
+	}
+
+	lock_sock(sk);
+
+	/* Send a DISC */
+	if (sk->sk_state == LLCP_CONNECTED)
+		nfc_llcp_send_disconnect(llcp_sock);
+
+	if (sk->sk_state == LLCP_LISTEN) {
+		struct nfc_llcp_sock *lsk, *n;
+		struct sock *accept_sk;
+
+		list_for_each_entry_safe(lsk, n, &llcp_sock->accept_queue,
+					 accept_queue) {
+			accept_sk = &lsk->sk;
+			lock_sock(accept_sk);
+
+			nfc_llcp_send_disconnect(lsk);
+			nfc_llcp_accept_unlink(accept_sk);
+
+			release_sock(accept_sk);
+		}
+	}
+
+	if (sock->type == SOCK_RAW)
+		nfc_llcp_sock_unlink(&local->raw_sockets, sk);
+	else if (sk->sk_state == LLCP_CONNECTING)
+		nfc_llcp_sock_unlink(&local->connecting_sockets, sk);
+	else
+		nfc_llcp_sock_unlink(&local->sockets, sk);
+
+	if (llcp_sock->reserved_ssap < LLCP_SAP_MAX)
+		nfc_llcp_put_ssap(llcp_sock->local, llcp_sock->ssap);
+
+	release_sock(sk);
+
+out:
+	sock_orphan(sk);
+	sock_put(sk);
+
+	return err;
+}
+
+static int llcp_sock_connect(struct socket *sock, struct sockaddr_unsized *_addr,
+			     int len, int flags)
+{
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	struct sockaddr_nfc_llcp *addr = (struct sockaddr_nfc_llcp *)_addr;
+	struct nfc_dev *dev;
+	struct nfc_llcp_local *local;
+	int ret = 0;
+
+	pr_debug("sock %p sk %p flags 0x%x\n", sock, sk, flags);
+
+	if (!addr || len < sizeof(*addr) || addr->sa_family != AF_NFC)
+		return -EINVAL;
+
+	if (addr->service_name_len == 0 && addr->dsap == 0)
+		return -EINVAL;
+
+	pr_debug("addr dev_idx=%u target_idx=%u protocol=%u\n", addr->dev_idx,
+		 addr->target_idx, addr->nfc_protocol);
+
+	lock_sock(sk);
+
+	if (sk->sk_state == LLCP_CONNECTED) {
+		ret = -EISCONN;
+		goto error;
+	}
+	if (sk->sk_state == LLCP_CONNECTING) {
+		ret = -EINPROGRESS;
+		goto error;
+	}
+
+	dev = nfc_get_device(addr->dev_idx);
+	if (dev == NULL) {
+		ret = -ENODEV;
+		goto error;
+	}
+
+	local = nfc_llcp_find_local(dev);
+	if (local == NULL) {
+		ret = -ENODEV;
+		goto put_dev;
+	}
+
+	device_lock(&dev->dev);
+	if (dev->dep_link_up == false) {
+		ret = -ENOLINK;
+		device_unlock(&dev->dev);
+		goto sock_llcp_put_local;
+	}
+	device_unlock(&dev->dev);
+
+	if (local->rf_mode == NFC_RF_INITIATOR &&
+	    addr->target_idx != local->target_idx) {
+		ret = -ENOLINK;
+		goto sock_llcp_put_local;
+	}
+
+	llcp_sock->dev = dev;
+	llcp_sock->local = local;
+	llcp_sock->ssap = nfc_llcp_get_local_ssap(local);
+	if (llcp_sock->ssap == LLCP_SAP_MAX) {
+		ret = -ENOMEM;
+		goto sock_llcp_nullify;
+	}
+
+	llcp_sock->reserved_ssap = llcp_sock->ssap;
+
+	if (addr->service_name_len == 0)
+		llcp_sock->dsap = addr->dsap;
+	else
+		llcp_sock->dsap = LLCP_SAP_SDP;
+	llcp_sock->nfc_protocol = addr->nfc_protocol;
+	llcp_sock->service_name_len = min_t(unsigned int,
+					    addr->service_name_len,
+					    NFC_LLCP_MAX_SERVICE_NAME);
+	llcp_sock->service_name = kmemdup(addr->service_name,
+					  llcp_sock->service_name_len,
+					  GFP_KERNEL);
+	if (!llcp_sock->service_name) {
+		ret = -ENOMEM;
+		goto sock_llcp_release;
+	}
+
+	nfc_llcp_sock_link(&local->connecting_sockets, sk);
+
+	ret = nfc_llcp_send_connect(llcp_sock);
+	if (ret)
+		goto sock_unlink;
+
+	sk->sk_state = LLCP_CONNECTING;
+
+	ret = sock_wait_state(sk, LLCP_CONNECTED,
+			      sock_sndtimeo(sk, flags & O_NONBLOCK));
+	if (ret && ret != -EINPROGRESS)
+		goto sock_unlink;
+
+	release_sock(sk);
+
+	return ret;
+
+sock_unlink:
+	nfc_llcp_sock_unlink(&local->connecting_sockets, sk);
+	kfree(llcp_sock->service_name);
+	llcp_sock->service_name = NULL;
+
+sock_llcp_release:
+	nfc_llcp_put_ssap(local, llcp_sock->ssap);
+
+sock_llcp_nullify:
+	llcp_sock->local = NULL;
+	llcp_sock->dev = NULL;
+
+sock_llcp_put_local:
+	nfc_llcp_local_put(local);
+
+put_dev:
+	nfc_put_device(dev);
+
+error:
+	release_sock(sk);
+	return ret;
+}
+
+static int llcp_sock_sendmsg(struct socket *sock, struct msghdr *msg,
+			     size_t len)
+{
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+	int ret;
+
+	pr_debug("sock %p sk %p", sock, sk);
+
+	ret = sock_error(sk);
+	if (ret)
+		return ret;
+
+	if (msg->msg_flags & MSG_OOB)
+		return -EOPNOTSUPP;
+
+	lock_sock(sk);
+
+	if (!llcp_sock->local) {
+		release_sock(sk);
+		return -ENODEV;
+	}
+
+	if (sk->sk_type == SOCK_DGRAM) {
+		if (sk->sk_state != LLCP_BOUND) {
+			release_sock(sk);
+			return -ENOTCONN;
+		}
+
+		DECLARE_SOCKADDR(struct sockaddr_nfc_llcp *, addr,
+				 msg->msg_name);
+
+		if (msg->msg_namelen < sizeof(*addr)) {
+			release_sock(sk);
+			return -EINVAL;
+		}
+
+		release_sock(sk);
+
+		return nfc_llcp_send_ui_frame(llcp_sock, addr->dsap, addr->ssap,
+					      msg, len);
+	}
+
+	if (sk->sk_state != LLCP_CONNECTED) {
+		release_sock(sk);
+		return -ENOTCONN;
+	}
+
+	release_sock(sk);
+
+	return nfc_llcp_send_i_frame(llcp_sock, msg, len);
+}
+
+static int llcp_sock_recvmsg(struct socket *sock, struct msghdr *msg,
+			     size_t len, int flags)
+{
+	struct sock *sk = sock->sk;
+	unsigned int copied, rlen;
+	struct sk_buff *skb, *cskb;
+	int err = 0;
+
+	pr_debug("%p %zu\n", sk, len);
+
+	lock_sock(sk);
+
+	if (sk->sk_state == LLCP_CLOSED &&
+	    skb_queue_empty(&sk->sk_receive_queue)) {
+		release_sock(sk);
+		return 0;
+	}
+
+	release_sock(sk);
+
+	if (flags & (MSG_OOB))
+		return -EOPNOTSUPP;
+
+	skb = skb_recv_datagram(sk, flags, &err);
+	if (!skb) {
+		pr_err("Recv datagram failed state %d %d %d",
+		       sk->sk_state, err, sock_error(sk));
+
+		if (sk->sk_shutdown & RCV_SHUTDOWN)
+			return 0;
+
+		return err;
+	}
+
+	rlen = skb->len;		/* real length of skb */
+	copied = min_t(unsigned int, rlen, len);
+
+	cskb = skb;
+	if (skb_copy_datagram_msg(cskb, 0, msg, copied)) {
+		if (!(flags & MSG_PEEK))
+			skb_queue_head(&sk->sk_receive_queue, skb);
+		return -EFAULT;
+	}
+
+	sock_recv_timestamp(msg, sk, skb);
+
+	if (sk->sk_type == SOCK_DGRAM && msg->msg_name) {
+		struct nfc_llcp_ui_cb *ui_cb = nfc_llcp_ui_skb_cb(skb);
+		DECLARE_SOCKADDR(struct sockaddr_nfc_llcp *, sockaddr,
+				 msg->msg_name);
+
+		msg->msg_namelen = sizeof(struct sockaddr_nfc_llcp);
+
+		pr_debug("Datagram socket %d %d\n", ui_cb->dsap, ui_cb->ssap);
+
+		memset(sockaddr, 0, sizeof(*sockaddr));
+		sockaddr->sa_family = AF_NFC;
+		sockaddr->nfc_protocol = NFC_PROTO_NFC_DEP;
+		sockaddr->dsap = ui_cb->dsap;
+		sockaddr->ssap = ui_cb->ssap;
+	}
+
+	/* Mark read part of skb as used */
+	if (!(flags & MSG_PEEK)) {
+
+		/* SOCK_STREAM: re-queue skb if it contains unreceived data */
+		if (sk->sk_type == SOCK_STREAM ||
+		    sk->sk_type == SOCK_DGRAM ||
+		    sk->sk_type == SOCK_RAW) {
+			skb_pull(skb, copied);
+			if (skb->len) {
+				skb_queue_head(&sk->sk_receive_queue, skb);
+				goto done;
+			}
+		}
+
+		kfree_skb(skb);
+	}
+
+	/* XXX Queue backlogged skbs */
+
+done:
+	/* SOCK_SEQPACKET: return real length if MSG_TRUNC is set */
+	if (sk->sk_type == SOCK_SEQPACKET && (flags & MSG_TRUNC))
+		copied = rlen;
+
+	return copied;
+}
+
+static const struct proto_ops llcp_sock_ops = {
+	.family         = PF_NFC,
+	.owner          = THIS_MODULE,
+	.bind           = llcp_sock_bind,
+	.connect        = llcp_sock_connect,
+	.release        = llcp_sock_release,
+	.socketpair     = sock_no_socketpair,
+	.accept         = llcp_sock_accept,
+	.getname        = llcp_sock_getname,
+	.poll           = llcp_sock_poll,
+	.ioctl          = sock_no_ioctl,
+	.listen         = llcp_sock_listen,
+	.shutdown       = sock_no_shutdown,
+	.setsockopt     = nfc_llcp_setsockopt,
+	.getsockopt     = nfc_llcp_getsockopt,
+	.sendmsg        = llcp_sock_sendmsg,
+	.recvmsg        = llcp_sock_recvmsg,
+	.mmap           = sock_no_mmap,
+};
+
+static const struct proto_ops llcp_rawsock_ops = {
+	.family         = PF_NFC,
+	.owner          = THIS_MODULE,
+	.bind           = llcp_raw_sock_bind,
+	.connect        = sock_no_connect,
+	.release        = llcp_sock_release,
+	.socketpair     = sock_no_socketpair,
+	.accept         = sock_no_accept,
+	.getname        = llcp_sock_getname,
+	.poll           = llcp_sock_poll,
+	.ioctl          = sock_no_ioctl,
+	.listen         = sock_no_listen,
+	.shutdown       = sock_no_shutdown,
+	.sendmsg        = sock_no_sendmsg,
+	.recvmsg        = llcp_sock_recvmsg,
+	.mmap           = sock_no_mmap,
+};
+
+static void llcp_sock_destruct(struct sock *sk)
+{
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+
+	pr_debug("%p\n", sk);
+
+	if (sk->sk_state == LLCP_CONNECTED)
+		nfc_put_device(llcp_sock->dev);
+
+	skb_queue_purge(&sk->sk_receive_queue);
+
+	nfc_llcp_sock_free(llcp_sock);
+
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		pr_err("Freeing alive NFC LLCP socket %p\n", sk);
+		return;
+	}
+}
+
+struct sock *nfc_llcp_sock_alloc(struct socket *sock, int type, gfp_t gfp, int kern)
+{
+	struct sock *sk;
+	struct nfc_llcp_sock *llcp_sock;
+
+	sk = sk_alloc(&init_net, PF_NFC, gfp, &llcp_sock_proto, kern);
+	if (!sk)
+		return NULL;
+
+	llcp_sock = nfc_llcp_sock(sk);
+
+	sock_init_data(sock, sk);
+	sk->sk_state = LLCP_CLOSED;
+	sk->sk_protocol = NFC_SOCKPROTO_LLCP;
+	sk->sk_type = type;
+	sk->sk_destruct = llcp_sock_destruct;
+
+	llcp_sock->ssap = 0;
+	llcp_sock->dsap = LLCP_SAP_SDP;
+	llcp_sock->rw = LLCP_MAX_RW + 1;
+	llcp_sock->miux = cpu_to_be16(LLCP_MAX_MIUX + 1);
+	llcp_sock->send_n = llcp_sock->send_ack_n = 0;
+	llcp_sock->recv_n = llcp_sock->recv_ack_n = 0;
+	llcp_sock->remote_ready = 1;
+	llcp_sock->reserved_ssap = LLCP_SAP_MAX;
+	nfc_llcp_socket_remote_param_init(llcp_sock);
+	skb_queue_head_init(&llcp_sock->tx_queue);
+	skb_queue_head_init(&llcp_sock->tx_pending_queue);
+	INIT_LIST_HEAD(&llcp_sock->accept_queue);
+
+	if (sock != NULL)
+		sock->state = SS_UNCONNECTED;
+
+	return sk;
+}
+
+void nfc_llcp_sock_free(struct nfc_llcp_sock *sock)
+{
+	kfree(sock->service_name);
+
+	skb_queue_purge(&sock->tx_queue);
+	skb_queue_purge(&sock->tx_pending_queue);
+
+	list_del_init(&sock->accept_queue);
+
+	sock->parent = NULL;
+
+	nfc_llcp_local_put(sock->local);
+}
+
+static int llcp_sock_create(struct net *net, struct socket *sock,
+			    const struct nfc_protocol *nfc_proto, int kern)
+{
+	struct sock *sk;
+
+	pr_debug("%p\n", sock);
+
+	if (sock->type != SOCK_STREAM &&
+	    sock->type != SOCK_DGRAM &&
+	    sock->type != SOCK_RAW)
+		return -ESOCKTNOSUPPORT;
+
+	if (sock->type == SOCK_RAW) {
+		if (!capable(CAP_NET_RAW))
+			return -EPERM;
+		sock->ops = &llcp_rawsock_ops;
+	} else {
+		sock->ops = &llcp_sock_ops;
+	}
+
+	sk = nfc_llcp_sock_alloc(sock, sock->type, GFP_ATOMIC, kern);
+	if (sk == NULL)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static const struct nfc_protocol llcp_nfc_proto = {
+	.id	  = NFC_SOCKPROTO_LLCP,
+	.proto    = &llcp_sock_proto,
+	.owner    = THIS_MODULE,
+	.create   = llcp_sock_create
+};
+
+int __init nfc_llcp_sock_init(void)
+{
+	return nfc_proto_register(&llcp_nfc_proto);
+}
+
+void nfc_llcp_sock_exit(void)
+{
+	nfc_proto_unregister(&llcp_nfc_proto);
+}