NFC: Initial LLCP support

This patch is an initial implementation for the NFC Logical Link Control
protocol. It's also known as NFC peer to peer mode.
This is a basic implementation as it lacks SDP (services Discovery
Protocol), frames aggregation support, and frame rejecion parsing.
Follow up patches will implement those missing features.
This code has been tested against a Nexus S phone implementing LLCP 1.0.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 675 insertions, 0 deletions

diff --git a/net/nfc/llcp/sock.c b/net/nfc/llcp/sock.c
new file mode 100644
index 000000000000..f738ccd535f1
--- /dev/null
+++ b/net/nfc/llcp/sock.c
@@ -0,0 +1,675 @@
+/*
+ * Copyright (C) 2011  Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the
+ * Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#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 "../nfc.h"
+#include "llcp.h"
+
+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 *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;
+
+	pr_debug("sk %p addr %p family %d\n", sk, addr, addr->sa_family);
+
+	if (!addr || addr->sa_family != AF_NFC)
+		return -EINVAL;
+
+	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);
+
+	llcp_sock->ssap = nfc_llcp_get_sdp_ssap(local, llcp_sock);
+	if (llcp_sock->ssap == LLCP_MAX_SAP)
+		goto put_dev;
+
+	local->sockets[llcp_sock->ssap] = llcp_sock;
+
+	pr_debug("Socket bound to SAP %d\n", llcp_sock->ssap);
+
+	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;
+}
+
+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) {
+			nfc_llcp_accept_unlink(sk);
+			if (newsock)
+				sock_graft(sk, newsock);
+
+			release_sock(sk);
+
+			pr_debug("Returning sk state %d\n", sk->sk_state);
+
+			return sk;
+		}
+
+		release_sock(sk);
+	}
+
+	return NULL;
+}
+
+static int llcp_sock_accept(struct socket *sock, struct socket *newsock,
+								int flags)
+{
+	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, 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 *addr,
+			     int *len, int peer)
+{
+	struct sockaddr_nfc_llcp *llcp_addr = (struct sockaddr_nfc_llcp *) addr;
+	struct sock *sk = sock->sk;
+	struct nfc_llcp_sock *llcp_sock = nfc_llcp_sock(sk);
+
+	pr_debug("%p\n", sk);
+
+	addr->sa_family = AF_NFC;
+	*len = sizeof(struct sockaddr_nfc_llcp);
+
+	llcp_addr->dev_idx = llcp_sock->dev->idx;
+	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);
+
+	return 0;
+}
+
+static inline unsigned int llcp_accept_poll(struct sock *parent)
+{
+	struct nfc_llcp_sock *llcp_sock, *n, *parent_sock;
+	struct sock *sk;
+
+	parent_sock = nfc_llcp_sock(parent);
+
+	list_for_each_entry_safe(llcp_sock, n, &parent_sock->accept_queue,
+								accept_queue) {
+		sk = &llcp_sock->sk;
+
+		if (sk->sk_state == LLCP_CONNECTED)
+			return POLLIN | POLLRDNORM;
+	}
+
+	return 0;
+}
+
+static unsigned int llcp_sock_poll(struct file *file, struct socket *sock,
+							poll_table *wait)
+{
+	struct sock *sk = sock->sk;
+	unsigned int mask = 0;
+
+	pr_debug("%p\n", sk);
+
+	sock_poll_wait(file, sk_sleep(sk), wait);
+
+	if (sk->sk_state == LLCP_LISTEN)
+		return llcp_accept_poll(sk);
+
+	if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
+		mask |= POLLERR;
+
+	if (!skb_queue_empty(&sk->sk_receive_queue))
+		mask |= POLLIN;
+
+	if (sk->sk_state == LLCP_CLOSED)
+		mask |= POLLHUP;
+
+	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);
+
+	if (!sk)
+		return 0;
+
+	pr_debug("%p\n", sk);
+
+	local = llcp_sock->local;
+	if (local == NULL)
+		return -ENODEV;
+
+	mutex_lock(&local->socket_lock);
+
+	if (llcp_sock == local->sockets[llcp_sock->ssap]) {
+		local->sockets[llcp_sock->ssap] = NULL;
+	} else {
+		struct nfc_llcp_sock *parent, *s, *n;
+
+		parent = local->sockets[llcp_sock->ssap];
+
+		list_for_each_entry_safe(s, n, &parent->list, list)
+			if (llcp_sock == s) {
+				list_del(&s->list);
+				break;
+			}
+
+	}
+
+	mutex_unlock(&local->socket_lock);
+
+	lock_sock(sk);
+
+	/* Send a DISC */
+	if (sk->sk_state == LLCP_CONNECTED)
+		nfc_llcp_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_disconnect(lsk);
+			nfc_llcp_accept_unlink(accept_sk);
+
+			release_sock(accept_sk);
+
+			sock_set_flag(sk, SOCK_DEAD);
+			sock_orphan(accept_sk);
+			sock_put(accept_sk);
+		}
+	}
+
+	/* Freeing the SAP */
+	if ((sk->sk_state == LLCP_CONNECTED
+			&& llcp_sock->ssap > LLCP_LOCAL_SAP_OFFSET) ||
+	    sk->sk_state == LLCP_BOUND ||
+	    sk->sk_state == LLCP_LISTEN)
+		nfc_llcp_put_ssap(llcp_sock->local, llcp_sock->ssap);
+
+	sock_set_flag(sk, SOCK_DEAD);
+
+	release_sock(sk);
+
+	sock_orphan(sk);
+	sock_put(sk);
+
+	return 0;
+}
+
+static int llcp_sock_connect(struct socket *sock, struct sockaddr *_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(struct sockaddr_nfc) ||
+			addr->sa_family != AF_NFC) {
+		pr_err("Invalid socket\n");
+		return -EINVAL;
+	}
+
+	if (addr->service_name_len == 0 && addr->dsap == 0) {
+		pr_err("Missing service name or dsap\n");
+		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;
+	}
+
+	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 put_dev;
+	}
+	device_unlock(&dev->dev);
+
+	if (local->rf_mode == NFC_RF_INITIATOR &&
+			addr->target_idx != local->target_idx) {
+		ret = -ENOLINK;
+		goto put_dev;
+	}
+
+	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 put_dev;
+	}
+	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);
+
+	local->sockets[llcp_sock->ssap] = llcp_sock;
+
+	ret = nfc_llcp_send_connect(llcp_sock);
+	if (ret)
+		goto put_dev;
+
+	sk->sk_state = LLCP_CONNECTED;
+
+	release_sock(sk);
+	return 0;
+
+put_dev:
+	nfc_put_device(dev);
+
+error:
+	release_sock(sk);
+	return ret;
+}
+
+static int llcp_sock_recvmsg(struct kiocb *iocb, struct socket *sock,
+			     struct msghdr *msg, size_t len, int flags)
+{
+	int noblock = flags & MSG_DONTWAIT;
+	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, noblock, &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 (memcpy_toiovec(msg->msg_iov, cskb->data, copied)) {
+		if (!(flags & MSG_PEEK))
+			skb_queue_head(&sk->sk_receive_queue, skb);
+		return -EFAULT;
+	}
+
+	/* 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) {
+			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     = sock_no_setsockopt,
+	.getsockopt     = sock_no_getsockopt,
+	.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)
+{
+	struct sock *sk;
+	struct nfc_llcp_sock *llcp_sock;
+
+	sk = sk_alloc(&init_net, PF_NFC, gfp, &llcp_sock_proto);
+	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->send_n = llcp_sock->send_ack_n = 0;
+	llcp_sock->recv_n = llcp_sock->recv_ack_n = 0;
+	llcp_sock->remote_ready = 1;
+	skb_queue_head_init(&llcp_sock->tx_queue);
+	skb_queue_head_init(&llcp_sock->tx_pending_queue);
+	skb_queue_head_init(&llcp_sock->tx_backlog_queue);
+	INIT_LIST_HEAD(&llcp_sock->list);
+	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);
+	skb_queue_purge(&sock->tx_backlog_queue);
+
+	list_del_init(&sock->accept_queue);
+
+	sock->parent = NULL;
+}
+
+static int llcp_sock_create(struct net *net, struct socket *sock,
+				const struct nfc_protocol *nfc_proto)
+{
+	struct sock *sk;
+
+	pr_debug("%p\n", sock);
+
+	if (sock->type != SOCK_STREAM && sock->type != SOCK_DGRAM)
+		return -ESOCKTNOSUPPORT;
+
+	sock->ops = &llcp_sock_ops;
+
+	sk = nfc_llcp_sock_alloc(sock, sock->type, GFP_ATOMIC);
+	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);
+}