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tuntap_user.c

/* 
 * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 * Licensed under the GPL
 */

#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <linux/if_tun.h>
#include <net/if.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <sys/uio.h>
#include "kern_constants.h"
#include "os.h"
#include "tuntap.h"
#include "user.h"

static int tuntap_user_init(void *data, void *dev)
{
      struct tuntap_data *pri = data;

      pri->dev = dev;
      return 0;
}

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

      tap_check_ips(pri->gate_addr, addr);
      if ((pri->fd == -1) || pri->fixed_config)
            return;
      open_addr(addr, netmask, pri->dev_name);
}

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

      if ((pri->fd == -1) || pri->fixed_config)
            return;
      close_addr(addr, netmask, pri->dev_name);
}

struct tuntap_pre_exec_data {
      int stdout;
      int close_me;
};

static void tuntap_pre_exec(void *arg)
{
      struct tuntap_pre_exec_data *data = arg;

      dup2(data->stdout, 1);
      close(data->close_me);
}

static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote,
                       char *buffer, int buffer_len, int *used_out)
{
      struct tuntap_pre_exec_data data;
      char version_buf[sizeof("nnnnn\0")];
      char *argv[] = { "uml_net", version_buf, "tuntap", "up", gate,
                   NULL };
      char buf[CMSG_SPACE(sizeof(*fd_out))];
      struct msghdr msg;
      struct cmsghdr *cmsg;
      struct iovec iov;
      int pid, n, err;

      sprintf(version_buf, "%d", UML_NET_VERSION);

      data.stdout = remote;
      data.close_me = me;

      pid = run_helper(tuntap_pre_exec, &data, argv);

      if (pid < 0)
            return -pid;

      close(remote);

      msg.msg_name = NULL;
      msg.msg_namelen = 0;
      if (buffer != NULL) {
            iov = ((struct iovec) { buffer, buffer_len });
            msg.msg_iov = &iov;
            msg.msg_iovlen = 1;
      }
      else {
            msg.msg_iov = NULL;
            msg.msg_iovlen = 0;
      }
      msg.msg_control = buf;
      msg.msg_controllen = sizeof(buf);
      msg.msg_flags = 0;
      n = recvmsg(me, &msg, 0);
      *used_out = n;
      if (n < 0) {
            err = -errno;
            printk(UM_KERN_ERR "tuntap_open_tramp : recvmsg failed - "
                   "errno = %d\n", errno);
            return err;
      }
      helper_wait(pid, 0, "tuntap_open_tramp");

      cmsg = CMSG_FIRSTHDR(&msg);
      if (cmsg == NULL) {
            printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
                   "message\n");
            return -EINVAL;
      }
      if ((cmsg->cmsg_level != SOL_SOCKET) ||
         (cmsg->cmsg_type != SCM_RIGHTS)) {
            printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
                   "descriptor\n");
            return -EINVAL;
      }
      *fd_out = ((int *) CMSG_DATA(cmsg))[0];
      os_set_exec_close(*fd_out);
      return 0;
}

static int tuntap_open(void *data)
{
      struct ifreq ifr;
      struct tuntap_data *pri = data;
      char *output, *buffer;
      int err, fds[2], len, used;

      err = tap_open_common(pri->dev, pri->gate_addr);
      if (err < 0)
            return err;

      if (pri->fixed_config) {
            pri->fd = os_open_file("/dev/net/tun",
                               of_cloexec(of_rdwr(OPENFLAGS())), 0);
            if (pri->fd < 0) {
                  printk(UM_KERN_ERR "Failed to open /dev/net/tun, "
                         "err = %d\n", -pri->fd);
                  return pri->fd;
            }
            memset(&ifr, 0, sizeof(ifr));
            ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
            strlcpy(ifr.ifr_name, pri->dev_name, sizeof(ifr.ifr_name));
            if (ioctl(pri->fd, TUNSETIFF, (void *) &ifr) < 0) {
                  err = -errno;
                  printk(UM_KERN_ERR "TUNSETIFF failed, errno = %d\n",
                         errno);
                  close(pri->fd);
                  return err;
            }
      }
      else {
            err = socketpair(AF_UNIX, SOCK_DGRAM, 0, fds);
            if (err) {
                  err = -errno;
                  printk(UM_KERN_ERR "tuntap_open : socketpair failed - "
                         "errno = %d\n", errno);
                  return err;
            }

            buffer = get_output_buffer(&len);
            if (buffer != NULL)
                  len--;
            used = 0;

            err = tuntap_open_tramp(pri->gate_addr, &pri->fd, fds[0],
                              fds[1], buffer, len, &used);

            output = buffer;
            if (err < 0) {
                  printk("%s", output);
                  free_output_buffer(buffer);
                  printk(UM_KERN_ERR "tuntap_open_tramp failed - "
                         "err = %d\n", -err);
                  return err;
            }

            pri->dev_name = uml_strdup(buffer);
            output += IFNAMSIZ;
            printk("%s", output);
            free_output_buffer(buffer);

            close(fds[0]);
            iter_addresses(pri->dev, open_addr, pri->dev_name);
      }

      return pri->fd;
}

static void tuntap_close(int fd, void *data)
{
      struct tuntap_data *pri = data;

      if (!pri->fixed_config)
            iter_addresses(pri->dev, close_addr, pri->dev_name);
      close(fd);
      pri->fd = -1;
}

const struct net_user_info tuntap_user_info = {
      .init       = tuntap_user_init,
      .open       = tuntap_open,
      .close            = tuntap_close,
      .remove           = NULL,
      .add_address      = tuntap_add_addr,
      .delete_address = tuntap_del_addr,
      .mtu        = ETH_MAX_PACKET,
      .max_packet = ETH_MAX_PACKET + ETH_HEADER_OTHER,
};

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