icmp_socket.c

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/* Copyright (C) 2007-2012 B.A.T.M.A.N. contributors:
 *
 * Marek Lindner
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU General Public
 * License as published by the Free Software Foundation.
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA
 */

#include "main.h"
#include <linux/debugfs.h>
#include <linux/slab.h>
#include "icmp_socket.h"
#include "send.h"
#include "hash.h"
#include "originator.h"
#include "hard-interface.h"

static struct batadv_socket_client *batadv_socket_client_hash[256];

static void batadv_socket_add_packet(struct batadv_socket_client *socket_client,
                     struct batadv_icmp_packet_rr *icmp_packet,
                     size_t icmp_len);

void batadv_socket_init(void)
{
    memset(batadv_socket_client_hash, 0, sizeof(batadv_socket_client_hash));
}

static int batadv_socket_open(struct inode *inode, struct file *file)
{
    unsigned int i;
    struct batadv_socket_client *socket_client;

    nonseekable_open(inode, file);

    socket_client = kmalloc(sizeof(*socket_client), GFP_KERNEL);

    if (!socket_client)
        return -ENOMEM;

    for (i = 0; i < ARRAY_SIZE(batadv_socket_client_hash); i++) {
        if (!batadv_socket_client_hash[i]) {
            batadv_socket_client_hash[i] = socket_client;
            break;
        }
    }

    if (i == ARRAY_SIZE(batadv_socket_client_hash)) {
        pr_err("Error - can't add another packet client: maximum number of clients reached\n");
        kfree(socket_client);
        return -EXFULL;
    }

    INIT_LIST_HEAD(&socket_client->queue_list);
    socket_client->queue_len = 0;
    socket_client->index = i;
    socket_client->bat_priv = inode->i_private;
    spin_lock_init(&socket_client->lock);
    init_waitqueue_head(&socket_client->queue_wait);

    file->private_data = socket_client;

    batadv_inc_module_count();
    return 0;
}

static int batadv_socket_release(struct inode *inode, struct file *file)
{
    struct batadv_socket_client *socket_client = file->private_data;
    struct batadv_socket_packet *socket_packet;
    struct list_head *list_pos, *list_pos_tmp;

    spin_lock_bh(&socket_client->lock);

    /* for all packets in the queue ... */
    list_for_each_safe(list_pos, list_pos_tmp, &socket_client->queue_list) {
        socket_packet = list_entry(list_pos,
                       struct batadv_socket_packet, list);

        list_del(list_pos);
        kfree(socket_packet);
    }

    batadv_socket_client_hash[socket_client->index] = NULL;
    spin_unlock_bh(&socket_client->lock);

    kfree(socket_client);
    batadv_dec_module_count();

    return 0;
}

static ssize_t batadv_socket_read(struct file *file, char __user *buf,
                  size_t count, loff_t *ppos)
{
    struct batadv_socket_client *socket_client = file->private_data;
    struct batadv_socket_packet *socket_packet;
    size_t packet_len;
    int error;

    if ((file->f_flags & O_NONBLOCK) && (socket_client->queue_len == 0))
        return -EAGAIN;

    if ((!buf) || (count < sizeof(struct batadv_icmp_packet)))
        return -EINVAL;

    if (!access_ok(VERIFY_WRITE, buf, count))
        return -EFAULT;

    error = wait_event_interruptible(socket_client->queue_wait,
                     socket_client->queue_len);

    if (error)
        return error;

    spin_lock_bh(&socket_client->lock);

    socket_packet = list_first_entry(&socket_client->queue_list,
                     struct batadv_socket_packet, list);
    list_del(&socket_packet->list);
    socket_client->queue_len--;

    spin_unlock_bh(&socket_client->lock);

    packet_len = min(count, socket_packet->icmp_len);
    error = copy_to_user(buf, &socket_packet->icmp_packet, packet_len);

    kfree(socket_packet);

    if (error)
        return -EFAULT;

    return packet_len;
}

static ssize_t batadv_socket_write(struct file *file, const char __user *buff,
                   size_t len, loff_t *off)
{
    struct batadv_socket_client *socket_client = file->private_data;
    struct batadv_priv *bat_priv = socket_client->bat_priv;
    struct batadv_hard_iface *primary_if = NULL;
    struct sk_buff *skb;
    struct batadv_icmp_packet_rr *icmp_packet;

    struct batadv_orig_node *orig_node = NULL;
    struct batadv_neigh_node *neigh_node = NULL;
    size_t packet_len = sizeof(struct batadv_icmp_packet);

    if (len < sizeof(struct batadv_icmp_packet)) {
        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
               "Error - can't send packet from char device: invalid packet size\n");
        return -EINVAL;
    }

    primary_if = batadv_primary_if_get_selected(bat_priv);

    if (!primary_if) {
        len = -EFAULT;
        goto out;
    }

    if (len >= sizeof(struct batadv_icmp_packet_rr))
        packet_len = sizeof(struct batadv_icmp_packet_rr);

    skb = dev_alloc_skb(packet_len + ETH_HLEN);
    if (!skb) {
        len = -ENOMEM;
        goto out;
    }

    skb_reserve(skb, ETH_HLEN);
    icmp_packet = (struct batadv_icmp_packet_rr *)skb_put(skb, packet_len);

    if (copy_from_user(icmp_packet, buff, packet_len)) {
        len = -EFAULT;
        goto free_skb;
    }

    if (icmp_packet->header.packet_type != BATADV_ICMP) {
        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
               "Error - can't send packet from char device: got bogus packet type (expected: BAT_ICMP)\n");
        len = -EINVAL;
        goto free_skb;
    }

    if (icmp_packet->msg_type != BATADV_ECHO_REQUEST) {
        batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
               "Error - can't send packet from char device: got bogus message type (expected: ECHO_REQUEST)\n");
        len = -EINVAL;
        goto free_skb;
    }

    icmp_packet->uid = socket_client->index;

    if (icmp_packet->header.version != BATADV_COMPAT_VERSION) {
        icmp_packet->msg_type = BATADV_PARAMETER_PROBLEM;
        icmp_packet->header.version = BATADV_COMPAT_VERSION;
        batadv_socket_add_packet(socket_client, icmp_packet,
                     packet_len);
        goto free_skb;
    }

    if (atomic_read(&bat_priv->mesh_state) != BATADV_MESH_ACTIVE)
        goto dst_unreach;

    orig_node = batadv_orig_hash_find(bat_priv, icmp_packet->dst);
    if (!orig_node)
        goto dst_unreach;

    neigh_node = batadv_orig_node_get_router(orig_node);
    if (!neigh_node)
        goto dst_unreach;

    if (!neigh_node->if_incoming)
        goto dst_unreach;

    if (neigh_node->if_incoming->if_status != BATADV_IF_ACTIVE)
        goto dst_unreach;

    memcpy(icmp_packet->orig,
           primary_if->net_dev->dev_addr, ETH_ALEN);

    if (packet_len == sizeof(struct batadv_icmp_packet_rr))
        memcpy(icmp_packet->rr,
               neigh_node->if_incoming->net_dev->dev_addr, ETH_ALEN);

    batadv_send_skb_packet(skb, neigh_node->if_incoming, neigh_node->addr);
    goto out;

dst_unreach:
    icmp_packet->msg_type = BATADV_DESTINATION_UNREACHABLE;
    batadv_socket_add_packet(socket_client, icmp_packet, packet_len);
free_skb:
    kfree_skb(skb);
out:
    if (primary_if)
        batadv_hardif_free_ref(primary_if);
    if (neigh_node)
        batadv_neigh_node_free_ref(neigh_node);
    if (orig_node)
        batadv_orig_node_free_ref(orig_node);
    return len;
}

static unsigned int batadv_socket_poll(struct file *file, poll_table *wait)
{
    struct batadv_socket_client *socket_client = file->private_data;

    poll_wait(file, &socket_client->queue_wait, wait);

    if (socket_client->queue_len > 0)
        return POLLIN | POLLRDNORM;

    return 0;
}

static const struct file_operations batadv_fops = {
    .owner = THIS_MODULE,
    .open = batadv_socket_open,
    .release = batadv_socket_release,
    .read = batadv_socket_read,
    .write = batadv_socket_write,
    .poll = batadv_socket_poll,
    .llseek = no_llseek,
};

int batadv_socket_setup(struct batadv_priv *bat_priv)
{
    struct dentry *d;

    if (!bat_priv->debug_dir)
        goto err;

    d = debugfs_create_file(BATADV_ICMP_SOCKET, S_IFREG | S_IWUSR | S_IRUSR,
                bat_priv->debug_dir, bat_priv, &batadv_fops);
    if (!d)
        goto err;

    return 0;

err:
    return -ENOMEM;
}

static void batadv_socket_add_packet(struct batadv_socket_client *socket_client,
                     struct batadv_icmp_packet_rr *icmp_packet,
                     size_t icmp_len)
{
    struct batadv_socket_packet *socket_packet;

    socket_packet = kmalloc(sizeof(*socket_packet), GFP_ATOMIC);

    if (!socket_packet)
        return;

    INIT_LIST_HEAD(&socket_packet->list);
    memcpy(&socket_packet->icmp_packet, icmp_packet, icmp_len);
    socket_packet->icmp_len = icmp_len;

    spin_lock_bh(&socket_client->lock);

    /* while waiting for the lock the socket_client could have been
     * deleted
     */
    if (!batadv_socket_client_hash[icmp_packet->uid]) {
        spin_unlock_bh(&socket_client->lock);
        kfree(socket_packet);
        return;
    }

    list_add_tail(&socket_packet->list, &socket_client->queue_list);
    socket_client->queue_len++;

    if (socket_client->queue_len > 100) {
        socket_packet = list_first_entry(&socket_client->queue_list,
                         struct batadv_socket_packet,
                         list);

        list_del(&socket_packet->list);
        kfree(socket_packet);
        socket_client->queue_len--;
    }

    spin_unlock_bh(&socket_client->lock);

    wake_up(&socket_client->queue_wait);
}

void batadv_socket_receive_packet(struct batadv_icmp_packet_rr *icmp_packet,
                  size_t icmp_len)
{
    struct batadv_socket_client *hash;

    hash = batadv_socket_client_hash[icmp_packet->uid];
    if (hash)
        batadv_socket_add_packet(hash, icmp_packet, icmp_len);
}