rawsock.c

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/*
 * Copyright (C) 2011 Instituto Nokia de Tecnologia
 *
 * Authors:
 *    Aloisio Almeida Jr <[email protected]>
 *    Lauro Ramos Venancio <[email protected]>
 *
 * 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) KBUILD_MODNAME ": %s: " fmt, __func__

#include <net/tcp_states.h>
#include <linux/nfc.h>
#include <linux/export.h>

#include "nfc.h"

static void rawsock_write_queue_purge(struct sock *sk)
{
    pr_debug("sk=%p\n", sk);

    spin_lock_bh(&sk->sk_write_queue.lock);
    __skb_queue_purge(&sk->sk_write_queue);
    nfc_rawsock(sk)->tx_work_scheduled = false;
    spin_unlock_bh(&sk->sk_write_queue.lock);
}

static void rawsock_report_error(struct sock *sk, int err)
{
    pr_debug("sk=%p err=%d\n", sk, err);

    sk->sk_shutdown = SHUTDOWN_MASK;
    sk->sk_err = -err;
    sk->sk_error_report(sk);

    rawsock_write_queue_purge(sk);
}

static int rawsock_release(struct socket *sock)
{
    struct sock *sk = sock->sk;

    pr_debug("sock=%p sk=%p\n", sock, sk);

    if (!sk)
        return 0;

    sock_orphan(sk);
    sock_put(sk);

    return 0;
}

static int rawsock_connect(struct socket *sock, struct sockaddr *_addr,
               int len, int flags)
{
    struct sock *sk = sock->sk;
    struct sockaddr_nfc *addr = (struct sockaddr_nfc *)_addr;
    struct nfc_dev *dev;
    int rc = 0;

    pr_debug("sock=%p sk=%p flags=%d\n", sock, sk, flags);

    if (!addr || len < sizeof(struct sockaddr_nfc) ||
        addr->sa_family != AF_NFC)
        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 (sock->state == SS_CONNECTED) {
        rc = -EISCONN;
        goto error;
    }

    dev = nfc_get_device(addr->dev_idx);
    if (!dev) {
        rc = -ENODEV;
        goto error;
    }

    if (addr->target_idx > dev->target_next_idx - 1 ||
        addr->target_idx < dev->target_next_idx - dev->n_targets) {
        rc = -EINVAL;
        goto error;
    }

    rc = nfc_activate_target(dev, addr->target_idx, addr->nfc_protocol);
    if (rc)
        goto put_dev;

    nfc_rawsock(sk)->dev = dev;
    nfc_rawsock(sk)->target_idx = addr->target_idx;
    sock->state = SS_CONNECTED;
    sk->sk_state = TCP_ESTABLISHED;
    sk->sk_state_change(sk);

    release_sock(sk);
    return 0;

put_dev:
    nfc_put_device(dev);
error:
    release_sock(sk);
    return rc;
}

static int rawsock_add_header(struct sk_buff *skb)
{
    *skb_push(skb, NFC_HEADER_SIZE) = 0;

    return 0;
}

static void rawsock_data_exchange_complete(void *context, struct sk_buff *skb,
                       int err)
{
    struct sock *sk = (struct sock *) context;

    BUG_ON(in_irq());

    pr_debug("sk=%p err=%d\n", sk, err);

    if (err)
        goto error;

    err = rawsock_add_header(skb);
    if (err)
        goto error;

    err = sock_queue_rcv_skb(sk, skb);
    if (err)
        goto error;

    spin_lock_bh(&sk->sk_write_queue.lock);
    if (!skb_queue_empty(&sk->sk_write_queue))
        schedule_work(&nfc_rawsock(sk)->tx_work);
    else
        nfc_rawsock(sk)->tx_work_scheduled = false;
    spin_unlock_bh(&sk->sk_write_queue.lock);

    sock_put(sk);
    return;

error:
    rawsock_report_error(sk, err);
    sock_put(sk);
}

static void rawsock_tx_work(struct work_struct *work)
{
    struct sock *sk = to_rawsock_sk(work);
    struct nfc_dev *dev = nfc_rawsock(sk)->dev;
    u32 target_idx = nfc_rawsock(sk)->target_idx;
    struct sk_buff *skb;
    int rc;

    pr_debug("sk=%p target_idx=%u\n", sk, target_idx);

    if (sk->sk_shutdown & SEND_SHUTDOWN) {
        rawsock_write_queue_purge(sk);
        return;
    }

    skb = skb_dequeue(&sk->sk_write_queue);

    sock_hold(sk);
    rc = nfc_data_exchange(dev, target_idx, skb,
                   rawsock_data_exchange_complete, sk);
    if (rc) {
        rawsock_report_error(sk, rc);
        sock_put(sk);
    }
}

static int rawsock_sendmsg(struct kiocb *iocb, struct socket *sock,
               struct msghdr *msg, size_t len)
{
    struct sock *sk = sock->sk;
    struct nfc_dev *dev = nfc_rawsock(sk)->dev;
    struct sk_buff *skb;
    int rc;

    pr_debug("sock=%p sk=%p len=%zu\n", sock, sk, len);

    if (msg->msg_namelen)
        return -EOPNOTSUPP;

    if (sock->state != SS_CONNECTED)
        return -ENOTCONN;

    skb = nfc_alloc_send_skb(dev, sk, msg->msg_flags, len, &rc);
    if (skb == NULL)
        return rc;

    rc = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
    if (rc < 0) {
        kfree_skb(skb);
        return rc;
    }

    spin_lock_bh(&sk->sk_write_queue.lock);
    __skb_queue_tail(&sk->sk_write_queue, skb);
    if (!nfc_rawsock(sk)->tx_work_scheduled) {
        schedule_work(&nfc_rawsock(sk)->tx_work);
        nfc_rawsock(sk)->tx_work_scheduled = true;
    }
    spin_unlock_bh(&sk->sk_write_queue.lock);

    return len;
}

static int rawsock_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;
    struct sk_buff *skb;
    int copied;
    int rc;

    pr_debug("sock=%p sk=%p len=%zu flags=%d\n", sock, sk, len, flags);

    skb = skb_recv_datagram(sk, flags, noblock, &rc);
    if (!skb)
        return rc;

    msg->msg_namelen = 0;

    copied = skb->len;
    if (len < copied) {
        msg->msg_flags |= MSG_TRUNC;
        copied = len;
    }

    rc = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, copied);

    skb_free_datagram(sk, skb);

    return rc ? : copied;
}


static const struct proto_ops rawsock_ops = {
    .family         = PF_NFC,
    .owner          = THIS_MODULE,
    .release        = rawsock_release,
    .bind           = sock_no_bind,
    .connect        = rawsock_connect,
    .socketpair     = sock_no_socketpair,
    .accept         = sock_no_accept,
    .getname        = sock_no_getname,
    .poll           = datagram_poll,
    .ioctl          = sock_no_ioctl,
    .listen         = sock_no_listen,
    .shutdown       = sock_no_shutdown,
    .setsockopt     = sock_no_setsockopt,
    .getsockopt     = sock_no_getsockopt,
    .sendmsg        = rawsock_sendmsg,
    .recvmsg        = rawsock_recvmsg,
    .mmap           = sock_no_mmap,
};

static void rawsock_destruct(struct sock *sk)
{
    pr_debug("sk=%p\n", sk);

    if (sk->sk_state == TCP_ESTABLISHED) {
        nfc_deactivate_target(nfc_rawsock(sk)->dev,
                      nfc_rawsock(sk)->target_idx);
        nfc_put_device(nfc_rawsock(sk)->dev);
    }

    skb_queue_purge(&sk->sk_receive_queue);

    if (!sock_flag(sk, SOCK_DEAD)) {
        pr_err("Freeing alive NFC raw socket %p\n", sk);
        return;
    }
}

static int rawsock_create(struct net *net, struct socket *sock,
              const struct nfc_protocol *nfc_proto)
{
    struct sock *sk;

    pr_debug("sock=%p\n", sock);

    if (sock->type != SOCK_SEQPACKET)
        return -ESOCKTNOSUPPORT;

    sock->ops = &rawsock_ops;

    sk = sk_alloc(net, PF_NFC, GFP_ATOMIC, nfc_proto->proto);
    if (!sk)
        return -ENOMEM;

    sock_init_data(sock, sk);
    sk->sk_protocol = nfc_proto->id;
    sk->sk_destruct = rawsock_destruct;
    sock->state = SS_UNCONNECTED;

    INIT_WORK(&nfc_rawsock(sk)->tx_work, rawsock_tx_work);
    nfc_rawsock(sk)->tx_work_scheduled = false;

    return 0;
}

static struct proto rawsock_proto = {
    .name     = "NFC_RAW",
    .owner    = THIS_MODULE,
    .obj_size = sizeof(struct nfc_rawsock),
};

static const struct nfc_protocol rawsock_nfc_proto = {
    .id   = NFC_SOCKPROTO_RAW,
    .proto    = &rawsock_proto,
    .owner    = THIS_MODULE,
    .create   = rawsock_create
};

int __init rawsock_init(void)
{
    int rc;

    rc = nfc_proto_register(&rawsock_nfc_proto);

    return rc;
}

void rawsock_exit(void)
{
    nfc_proto_unregister(&rawsock_nfc_proto);
}