ethertap_user.c

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/*
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Copyright (C) 2001 Lennert Buytenhek ([email protected]) and
 * James Leu ([email protected]).
 * Copyright (C) 2001 by various other people who didn't put their name here.
 * Licensed under the GPL.
 */

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include "etap.h"
#include <os.h>
#include <net_user.h>
#include <um_malloc.h>

#define MAX_PACKET ETH_MAX_PACKET

static int etap_user_init(void *data, void *dev)
{
    struct ethertap_data *pri = data;

    pri->dev = dev;
    return 0;
}

struct addr_change {
    enum { ADD_ADDR, DEL_ADDR } what;
    unsigned char addr[4];
    unsigned char netmask[4];
};

static void etap_change(int op, unsigned char *addr, unsigned char *netmask,
            int fd)
{
    struct addr_change change;
    char *output;
    int n;

    change.what = op;
    memcpy(change.addr, addr, sizeof(change.addr));
    memcpy(change.netmask, netmask, sizeof(change.netmask));
    CATCH_EINTR(n = write(fd, &change, sizeof(change)));
    if (n != sizeof(change)) {
        printk(UM_KERN_ERR "etap_change - request failed, err = %d\n",
               errno);
        return;
    }

    output = uml_kmalloc(UM_KERN_PAGE_SIZE, UM_GFP_KERNEL);
    if (output == NULL)
        printk(UM_KERN_ERR "etap_change : Failed to allocate output "
               "buffer\n");
    read_output(fd, output, UM_KERN_PAGE_SIZE);
    if (output != NULL) {
        printk("%s", output);
        kfree(output);
    }
}

static void etap_open_addr(unsigned char *addr, unsigned char *netmask,
               void *arg)
{
    etap_change(ADD_ADDR, addr, netmask, *((int *) arg));
}

static void etap_close_addr(unsigned char *addr, unsigned char *netmask,
                void *arg)
{
    etap_change(DEL_ADDR, addr, netmask, *((int *) arg));
}

struct etap_pre_exec_data {
    int control_remote;
    int control_me;
    int data_me;
};

static void etap_pre_exec(void *arg)
{
    struct etap_pre_exec_data *data = arg;

    dup2(data->control_remote, 1);
    close(data->data_me);
    close(data->control_me);
}

static int etap_tramp(char *dev, char *gate, int control_me,
              int control_remote, int data_me, int data_remote)
{
    struct etap_pre_exec_data pe_data;
    int pid, err, n;
    char version_buf[sizeof("nnnnn\0")];
    char data_fd_buf[sizeof("nnnnnn\0")];
    char gate_buf[sizeof("nnn.nnn.nnn.nnn\0")];
    char *setup_args[] = { "uml_net", version_buf, "ethertap", dev,
                   data_fd_buf, gate_buf, NULL };
    char *nosetup_args[] = { "uml_net", version_buf, "ethertap",
                 dev, data_fd_buf, NULL };
    char **args, c;

    sprintf(data_fd_buf, "%d", data_remote);
    sprintf(version_buf, "%d", UML_NET_VERSION);
    if (gate != NULL) {
        strcpy(gate_buf, gate);
        args = setup_args;
    }
    else args = nosetup_args;

    err = 0;
    pe_data.control_remote = control_remote;
    pe_data.control_me = control_me;
    pe_data.data_me = data_me;
    pid = run_helper(etap_pre_exec, &pe_data, args);

    if (pid < 0)
        err = pid;
    close(data_remote);
    close(control_remote);
    CATCH_EINTR(n = read(control_me, &c, sizeof(c)));
    if (n != sizeof(c)) {
        err = -errno;
        printk(UM_KERN_ERR "etap_tramp : read of status failed, "
               "err = %d\n", -err);
        return err;
    }
    if (c != 1) {
        printk(UM_KERN_ERR "etap_tramp : uml_net failed\n");
        err = helper_wait(pid);
    }
    return err;
}

static int etap_open(void *data)
{
    struct ethertap_data *pri = data;
    char *output;
    int data_fds[2], control_fds[2], err, output_len;

    err = tap_open_common(pri->dev, pri->gate_addr);
    if (err)
        return err;

    err = socketpair(AF_UNIX, SOCK_DGRAM, 0, data_fds);
    if (err) {
        err = -errno;
        printk(UM_KERN_ERR "etap_open - data socketpair failed - "
               "err = %d\n", errno);
        return err;
    }

    err = socketpair(AF_UNIX, SOCK_STREAM, 0, control_fds);
    if (err) {
        err = -errno;
        printk(UM_KERN_ERR "etap_open - control socketpair failed - "
               "err = %d\n", errno);
        goto out_close_data;
    }

    err = etap_tramp(pri->dev_name, pri->gate_addr, control_fds[0],
             control_fds[1], data_fds[0], data_fds[1]);
    output_len = UM_KERN_PAGE_SIZE;
    output = uml_kmalloc(output_len, UM_GFP_KERNEL);
    read_output(control_fds[0], output, output_len);

    if (output == NULL)
        printk(UM_KERN_ERR "etap_open : failed to allocate output "
               "buffer\n");
    else {
        printk("%s", output);
        kfree(output);
    }

    if (err < 0) {
        printk(UM_KERN_ERR "etap_tramp failed - err = %d\n", -err);
        goto out_close_control;
    }

    pri->data_fd = data_fds[0];
    pri->control_fd = control_fds[0];
    iter_addresses(pri->dev, etap_open_addr, &pri->control_fd);
    return data_fds[0];

out_close_control:
    close(control_fds[0]);
    close(control_fds[1]);
out_close_data:
    close(data_fds[0]);
    close(data_fds[1]);
    return err;
}

static void etap_close(int fd, void *data)
{
    struct ethertap_data *pri = data;

    iter_addresses(pri->dev, etap_close_addr, &pri->control_fd);
    close(fd);

    if (shutdown(pri->data_fd, SHUT_RDWR) < 0)
        printk(UM_KERN_ERR "etap_close - shutdown data socket failed, "
               "errno = %d\n", errno);

    if (shutdown(pri->control_fd, SHUT_RDWR) < 0)
        printk(UM_KERN_ERR "etap_close - shutdown control socket "
               "failed, errno = %d\n", errno);

    close(pri->data_fd);
    pri->data_fd = -1;
    close(pri->control_fd);
    pri->control_fd = -1;
}

static void etap_add_addr(unsigned char *addr, unsigned char *netmask,
              void *data)
{
    struct ethertap_data *pri = data;

    tap_check_ips(pri->gate_addr, addr);
    if (pri->control_fd == -1)
        return;
    etap_open_addr(addr, netmask, &pri->control_fd);
}

static void etap_del_addr(unsigned char *addr, unsigned char *netmask,
              void *data)
{
    struct ethertap_data *pri = data;

    if (pri->control_fd == -1)
        return;

    etap_close_addr(addr, netmask, &pri->control_fd);
}

const struct net_user_info ethertap_user_info = {
    .init       = etap_user_init,
    .open       = etap_open,
    .close      = etap_close,
    .remove     = NULL,
    .add_address    = etap_add_addr,
    .delete_address = etap_del_addr,
    .mtu        = ETH_MAX_PACKET,
    .max_packet = ETH_MAX_PACKET + ETH_HEADER_ETHERTAP,
};