chnl_net.c

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/*
 * Copyright (C) ST-Ericsson AB 2010
 * Authors: Sjur Brendeland/[email protected]
 *      Daniel Martensson / [email protected]
 * License terms: GNU General Public License (GPL) version 2
 */

#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__

#include <linux/fs.h>
#include <linux/hardirq.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/if_ether.h>
#include <linux/moduleparam.h>
#include <linux/ip.h>
#include <linux/sched.h>
#include <linux/sockios.h>
#include <linux/caif/if_caif.h>
#include <net/rtnetlink.h>
#include <net/caif/caif_layer.h>
#include <net/caif/cfpkt.h>
#include <net/caif/caif_dev.h>

/* GPRS PDP connection has MTU to 1500 */
#define GPRS_PDP_MTU 1500
/* 5 sec. connect timeout */
#define CONNECT_TIMEOUT (5 * HZ)
#define CAIF_NET_DEFAULT_QUEUE_LEN 500
#define UNDEF_CONNID 0xffffffff

/*This list is protected by the rtnl lock. */
static LIST_HEAD(chnl_net_list);

MODULE_LICENSE("GPL");
MODULE_ALIAS_RTNL_LINK("caif");

enum caif_states {
    CAIF_CONNECTED      = 1,
    CAIF_CONNECTING,
    CAIF_DISCONNECTED,
    CAIF_SHUTDOWN
};

struct chnl_net {
    struct cflayer chnl;
    struct net_device_stats stats;
    struct caif_connect_request conn_req;
    struct list_head list_field;
    struct net_device *netdev;
    char name[256];
    wait_queue_head_t netmgmt_wq;
    /* Flow status to remember and control the transmission. */
    bool flowenabled;
    enum caif_states state;
};

static void robust_list_del(struct list_head *delete_node)
{
    struct list_head *list_node;
    struct list_head *n;
    ASSERT_RTNL();
    list_for_each_safe(list_node, n, &chnl_net_list) {
        if (list_node == delete_node) {
            list_del(list_node);
            return;
        }
    }
    WARN_ON(1);
}

static int chnl_recv_cb(struct cflayer *layr, struct cfpkt *pkt)
{
    struct sk_buff *skb;
    struct chnl_net *priv;
    int pktlen;
    const u8 *ip_version;
    u8 buf;

    priv = container_of(layr, struct chnl_net, chnl);
    if (!priv)
        return -EINVAL;

    skb = (struct sk_buff *) cfpkt_tonative(pkt);

    /* Get length of CAIF packet. */
    pktlen = skb->len;

    /* Pass some minimum information and
     * send the packet to the net stack.
     */
    skb->dev = priv->netdev;

    /* check the version of IP */
    ip_version = skb_header_pointer(skb, 0, 1, &buf);
    if (!ip_version) {
        kfree_skb(skb);
        return -EINVAL;
    }

    switch (*ip_version >> 4) {
    case 4:
        skb->protocol = htons(ETH_P_IP);
        break;
    case 6:
        skb->protocol = htons(ETH_P_IPV6);
        break;
    default:
        kfree_skb(skb);
        priv->netdev->stats.rx_errors++;
        return -EINVAL;
    }

    /* If we change the header in loop mode, the checksum is corrupted. */
    if (priv->conn_req.protocol == CAIFPROTO_DATAGRAM_LOOP)
        skb->ip_summed = CHECKSUM_UNNECESSARY;
    else
        skb->ip_summed = CHECKSUM_NONE;

    if (in_interrupt())
        netif_rx(skb);
    else
        netif_rx_ni(skb);

    /* Update statistics. */
    priv->netdev->stats.rx_packets++;
    priv->netdev->stats.rx_bytes += pktlen;

    return 0;
}

static int delete_device(struct chnl_net *dev)
{
    ASSERT_RTNL();
    if (dev->netdev)
        unregister_netdevice(dev->netdev);
    return 0;
}

static void close_work(struct work_struct *work)
{
    struct chnl_net *dev = NULL;
    struct list_head *list_node;
    struct list_head *_tmp;

    rtnl_lock();
    list_for_each_safe(list_node, _tmp, &chnl_net_list) {
        dev = list_entry(list_node, struct chnl_net, list_field);
        if (dev->state == CAIF_SHUTDOWN)
            dev_close(dev->netdev);
    }
    rtnl_unlock();
}
static DECLARE_WORK(close_worker, close_work);

static void chnl_hold(struct cflayer *lyr)
{
    struct chnl_net *priv = container_of(lyr, struct chnl_net, chnl);
    dev_hold(priv->netdev);
}

static void chnl_put(struct cflayer *lyr)
{
    struct chnl_net *priv = container_of(lyr, struct chnl_net, chnl);
    dev_put(priv->netdev);
}

static void chnl_flowctrl_cb(struct cflayer *layr, enum caif_ctrlcmd flow,
                int phyid)
{
    struct chnl_net *priv = container_of(layr, struct chnl_net, chnl);
    pr_debug("NET flowctrl func called flow: %s\n",
        flow == CAIF_CTRLCMD_FLOW_ON_IND ? "ON" :
        flow == CAIF_CTRLCMD_INIT_RSP ? "INIT" :
        flow == CAIF_CTRLCMD_FLOW_OFF_IND ? "OFF" :
        flow == CAIF_CTRLCMD_DEINIT_RSP ? "CLOSE/DEINIT" :
        flow == CAIF_CTRLCMD_INIT_FAIL_RSP ? "OPEN_FAIL" :
        flow == CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND ?
         "REMOTE_SHUTDOWN" : "UKNOWN CTRL COMMAND");



    switch (flow) {
    case CAIF_CTRLCMD_FLOW_OFF_IND:
        priv->flowenabled = false;
        netif_stop_queue(priv->netdev);
        break;
    case CAIF_CTRLCMD_DEINIT_RSP:
        priv->state = CAIF_DISCONNECTED;
        break;
    case CAIF_CTRLCMD_INIT_FAIL_RSP:
        priv->state = CAIF_DISCONNECTED;
        wake_up_interruptible(&priv->netmgmt_wq);
        break;
    case CAIF_CTRLCMD_REMOTE_SHUTDOWN_IND:
        priv->state = CAIF_SHUTDOWN;
        netif_tx_disable(priv->netdev);
        schedule_work(&close_worker);
        break;
    case CAIF_CTRLCMD_FLOW_ON_IND:
        priv->flowenabled = true;
        netif_wake_queue(priv->netdev);
        break;
    case CAIF_CTRLCMD_INIT_RSP:
        caif_client_register_refcnt(&priv->chnl, chnl_hold, chnl_put);
        priv->state = CAIF_CONNECTED;
        priv->flowenabled = true;
        netif_wake_queue(priv->netdev);
        wake_up_interruptible(&priv->netmgmt_wq);
        break;
    default:
        break;
    }
}

static int chnl_net_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
    struct chnl_net *priv;
    struct cfpkt *pkt = NULL;
    int len;
    int result = -1;
    /* Get our private data. */
    priv = netdev_priv(dev);

    if (skb->len > priv->netdev->mtu) {
        pr_warn("Size of skb exceeded MTU\n");
        kfree_skb(skb);
        dev->stats.tx_errors++;
        return NETDEV_TX_OK;
    }

    if (!priv->flowenabled) {
        pr_debug("dropping packets flow off\n");
        kfree_skb(skb);
        dev->stats.tx_dropped++;
        return NETDEV_TX_OK;
    }

    if (priv->conn_req.protocol == CAIFPROTO_DATAGRAM_LOOP)
        swap(ip_hdr(skb)->saddr, ip_hdr(skb)->daddr);

    /* Store original SKB length. */
    len = skb->len;

    pkt = cfpkt_fromnative(CAIF_DIR_OUT, (void *) skb);

    /* Send the packet down the stack. */
    result = priv->chnl.dn->transmit(priv->chnl.dn, pkt);
    if (result) {
        dev->stats.tx_dropped++;
        return NETDEV_TX_OK;
    }

    /* Update statistics. */
    dev->stats.tx_packets++;
    dev->stats.tx_bytes += len;

    return NETDEV_TX_OK;
}

static int chnl_net_open(struct net_device *dev)
{
    struct chnl_net *priv = NULL;
    int result = -1;
    int llifindex, headroom, tailroom, mtu;
    struct net_device *lldev;
    ASSERT_RTNL();
    priv = netdev_priv(dev);
    if (!priv) {
        pr_debug("chnl_net_open: no priv\n");
        return -ENODEV;
    }

    if (priv->state != CAIF_CONNECTING) {
        priv->state = CAIF_CONNECTING;
        result = caif_connect_client(dev_net(dev), &priv->conn_req,
                        &priv->chnl, &llifindex,
                        &headroom, &tailroom);
        if (result != 0) {
                pr_debug("err: "
                     "Unable to register and open device,"
                     " Err:%d\n",
                     result);
                goto error;
        }

        lldev = dev_get_by_index(dev_net(dev), llifindex);

        if (lldev == NULL) {
            pr_debug("no interface?\n");
            result = -ENODEV;
            goto error;
        }

        dev->needed_tailroom = tailroom + lldev->needed_tailroom;
        dev->hard_header_len = headroom + lldev->hard_header_len +
            lldev->needed_tailroom;

        /*
         * MTU, head-room etc is not know before we have a
         * CAIF link layer device available. MTU calculation may
         * override initial RTNL configuration.
         * MTU is minimum of current mtu, link layer mtu pluss
         * CAIF head and tail, and PDP GPRS contexts max MTU.
         */
        mtu = min_t(int, dev->mtu, lldev->mtu - (headroom + tailroom));
        mtu = min_t(int, GPRS_PDP_MTU, mtu);
        dev_set_mtu(dev, mtu);
        dev_put(lldev);

        if (mtu < 100) {
            pr_warn("CAIF Interface MTU too small (%d)\n", mtu);
            result = -ENODEV;
            goto error;
        }
    }

    rtnl_unlock();  /* Release RTNL lock during connect wait */

    result = wait_event_interruptible_timeout(priv->netmgmt_wq,
                        priv->state != CAIF_CONNECTING,
                        CONNECT_TIMEOUT);

    rtnl_lock();

    if (result == -ERESTARTSYS) {
        pr_debug("wait_event_interruptible woken by a signal\n");
        result = -ERESTARTSYS;
        goto error;
    }

    if (result == 0) {
        pr_debug("connect timeout\n");
        caif_disconnect_client(dev_net(dev), &priv->chnl);
        priv->state = CAIF_DISCONNECTED;
        pr_debug("state disconnected\n");
        result = -ETIMEDOUT;
        goto error;
    }

    if (priv->state != CAIF_CONNECTED) {
        pr_debug("connect failed\n");
        result = -ECONNREFUSED;
        goto error;
    }
    pr_debug("CAIF Netdevice connected\n");
    return 0;

error:
    caif_disconnect_client(dev_net(dev), &priv->chnl);
    priv->state = CAIF_DISCONNECTED;
    pr_debug("state disconnected\n");
    return result;

}

static int chnl_net_stop(struct net_device *dev)
{
    struct chnl_net *priv;

    ASSERT_RTNL();
    priv = netdev_priv(dev);
    priv->state = CAIF_DISCONNECTED;
    caif_disconnect_client(dev_net(dev), &priv->chnl);
    return 0;
}

static int chnl_net_init(struct net_device *dev)
{
    struct chnl_net *priv;
    ASSERT_RTNL();
    priv = netdev_priv(dev);
    strncpy(priv->name, dev->name, sizeof(priv->name));
    return 0;
}

static void chnl_net_uninit(struct net_device *dev)
{
    struct chnl_net *priv;
    ASSERT_RTNL();
    priv = netdev_priv(dev);
    robust_list_del(&priv->list_field);
}

static const struct net_device_ops netdev_ops = {
    .ndo_open = chnl_net_open,
    .ndo_stop = chnl_net_stop,
    .ndo_init = chnl_net_init,
    .ndo_uninit = chnl_net_uninit,
    .ndo_start_xmit = chnl_net_start_xmit,
};

static void chnl_net_destructor(struct net_device *dev)
{
    struct chnl_net *priv = netdev_priv(dev);
    caif_free_client(&priv->chnl);
    free_netdev(dev);
}

static void ipcaif_net_setup(struct net_device *dev)
{
    struct chnl_net *priv;
    dev->netdev_ops = &netdev_ops;
    dev->destructor = chnl_net_destructor;
    dev->flags |= IFF_NOARP;
    dev->flags |= IFF_POINTOPOINT;
    dev->mtu = GPRS_PDP_MTU;
    dev->tx_queue_len = CAIF_NET_DEFAULT_QUEUE_LEN;

    priv = netdev_priv(dev);
    priv->chnl.receive = chnl_recv_cb;
    priv->chnl.ctrlcmd = chnl_flowctrl_cb;
    priv->netdev = dev;
    priv->conn_req.protocol = CAIFPROTO_DATAGRAM;
    priv->conn_req.link_selector = CAIF_LINK_HIGH_BANDW;
    priv->conn_req.priority = CAIF_PRIO_LOW;
    /* Insert illegal value */
    priv->conn_req.sockaddr.u.dgm.connection_id = UNDEF_CONNID;
    priv->flowenabled = false;

    init_waitqueue_head(&priv->netmgmt_wq);
}


static int ipcaif_fill_info(struct sk_buff *skb, const struct net_device *dev)
{
    struct chnl_net *priv;
    u8 loop;
    priv = netdev_priv(dev);
    if (nla_put_u32(skb, IFLA_CAIF_IPV4_CONNID,
            priv->conn_req.sockaddr.u.dgm.connection_id) ||
        nla_put_u32(skb, IFLA_CAIF_IPV6_CONNID,
            priv->conn_req.sockaddr.u.dgm.connection_id))
        goto nla_put_failure;
    loop = priv->conn_req.protocol == CAIFPROTO_DATAGRAM_LOOP;
    if (nla_put_u8(skb, IFLA_CAIF_LOOPBACK, loop))
        goto nla_put_failure;
    return 0;
nla_put_failure:
    return -EMSGSIZE;

}

static void caif_netlink_parms(struct nlattr *data[],
                struct caif_connect_request *conn_req)
{
    if (!data) {
        pr_warn("no params data found\n");
        return;
    }
    if (data[IFLA_CAIF_IPV4_CONNID])
        conn_req->sockaddr.u.dgm.connection_id =
            nla_get_u32(data[IFLA_CAIF_IPV4_CONNID]);
    if (data[IFLA_CAIF_IPV6_CONNID])
        conn_req->sockaddr.u.dgm.connection_id =
            nla_get_u32(data[IFLA_CAIF_IPV6_CONNID]);
    if (data[IFLA_CAIF_LOOPBACK]) {
        if (nla_get_u8(data[IFLA_CAIF_LOOPBACK]))
            conn_req->protocol = CAIFPROTO_DATAGRAM_LOOP;
        else
            conn_req->protocol = CAIFPROTO_DATAGRAM;
    }
}

static int ipcaif_newlink(struct net *src_net, struct net_device *dev,
              struct nlattr *tb[], struct nlattr *data[])
{
    int ret;
    struct chnl_net *caifdev;
    ASSERT_RTNL();
    caifdev = netdev_priv(dev);
    caif_netlink_parms(data, &caifdev->conn_req);
    dev_net_set(caifdev->netdev, src_net);

    ret = register_netdevice(dev);
    if (ret)
        pr_warn("device rtml registration failed\n");
    else
        list_add(&caifdev->list_field, &chnl_net_list);

    /* Use ifindex as connection id, and use loopback channel default. */
    if (caifdev->conn_req.sockaddr.u.dgm.connection_id == UNDEF_CONNID) {
        caifdev->conn_req.sockaddr.u.dgm.connection_id = dev->ifindex;
        caifdev->conn_req.protocol = CAIFPROTO_DATAGRAM_LOOP;
    }
    return ret;
}

static int ipcaif_changelink(struct net_device *dev, struct nlattr *tb[],
                struct nlattr *data[])
{
    struct chnl_net *caifdev;
    ASSERT_RTNL();
    caifdev = netdev_priv(dev);
    caif_netlink_parms(data, &caifdev->conn_req);
    netdev_state_change(dev);
    return 0;
}

static size_t ipcaif_get_size(const struct net_device *dev)
{
    return
        /* IFLA_CAIF_IPV4_CONNID */
        nla_total_size(4) +
        /* IFLA_CAIF_IPV6_CONNID */
        nla_total_size(4) +
        /* IFLA_CAIF_LOOPBACK */
        nla_total_size(2) +
        0;
}

static const struct nla_policy ipcaif_policy[IFLA_CAIF_MAX + 1] = {
    [IFLA_CAIF_IPV4_CONNID]       = { .type = NLA_U32 },
    [IFLA_CAIF_IPV6_CONNID]       = { .type = NLA_U32 },
    [IFLA_CAIF_LOOPBACK]          = { .type = NLA_U8 }
};


static struct rtnl_link_ops ipcaif_link_ops __read_mostly = {
    .kind       = "caif",
    .priv_size  = sizeof(struct chnl_net),
    .setup      = ipcaif_net_setup,
    .maxtype    = IFLA_CAIF_MAX,
    .policy     = ipcaif_policy,
    .newlink    = ipcaif_newlink,
    .changelink = ipcaif_changelink,
    .get_size   = ipcaif_get_size,
    .fill_info  = ipcaif_fill_info,

};

static int __init chnl_init_module(void)
{
    return rtnl_link_register(&ipcaif_link_ops);
}

static void __exit chnl_exit_module(void)
{
    struct chnl_net *dev = NULL;
    struct list_head *list_node;
    struct list_head *_tmp;
    rtnl_link_unregister(&ipcaif_link_ops);
    rtnl_lock();
    list_for_each_safe(list_node, _tmp, &chnl_net_list) {
        dev = list_entry(list_node, struct chnl_net, list_field);
        list_del(list_node);
        delete_device(dev);
    }
    rtnl_unlock();
}

module_init(chnl_init_module);
module_exit(chnl_exit_module);