arch/um/os-Linux/drivers/tuntap_user.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   4  */
   5
   6 #include <stdio.h>
   7 #include <unistd.h>
   8 #include <errno.h>
   9 #include <string.h>
  10 #include <linux/if_tun.h>
  11 #include <net/if.h>
  12 #include <sys/ioctl.h>
  13 #include <sys/socket.h>
  14 #include <sys/wait.h>
  15 #include <sys/uio.h>
  16 #include <kern_util.h>
  17 #include <os.h>
  18 #include "tuntap.h"
  19
  20 static int tuntap_user_init(void *data, void *dev)
  21 {
  22         struct tuntap_data *pri = data;
  23
  24         pri->dev = dev;
  25         return 0;
  26 }
  27
  28 static void tuntap_add_addr(unsigned char *addr, unsigned char *netmask,
  29                             void *data)
  30 {
  31         struct tuntap_data *pri = data;
  32
  33         tap_check_ips(pri->gate_addr, addr);
  34         if ((pri->fd == -1) || pri->fixed_config)
  35                 return;
  36         open_addr(addr, netmask, pri->dev_name);
  37 }
  38
  39 static void tuntap_del_addr(unsigned char *addr, unsigned char *netmask,
  40                             void *data)
  41 {
  42         struct tuntap_data *pri = data;
  43
  44         if ((pri->fd == -1) || pri->fixed_config)
  45                 return;
  46         close_addr(addr, netmask, pri->dev_name);
  47 }
  48
  49 struct tuntap_pre_exec_data {
  50         int stdout_fd;
  51         int close_me;
  52 };
  53
  54 static void tuntap_pre_exec(void *arg)
  55 {
  56         struct tuntap_pre_exec_data *data = arg;
  57
  58         dup2(data->stdout_fd, 1);
  59         close(data->close_me);
  60 }
  61
  62 static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote,
  63                              char *buffer, int buffer_len, int *used_out)
  64 {
  65         struct tuntap_pre_exec_data data;
  66         char version_buf[sizeof("nnnnn\0")];
  67         char *argv[] = { "uml_net", version_buf, "tuntap", "up", gate,
  68                          NULL };
  69         char buf[CMSG_SPACE(sizeof(*fd_out))];
  70         struct msghdr msg;
  71         struct cmsghdr *cmsg;
  72         struct iovec iov;
  73         int pid, n, err;
  74
  75         sprintf(version_buf, "%d", UML_NET_VERSION);
  76
  77         data.stdout_fd = remote;
  78         data.close_me = me;
  79
  80         pid = run_helper(tuntap_pre_exec, &data, argv);
  81
  82         if (pid < 0)
  83                 return pid;
  84
  85         close(remote);
  86
  87         msg.msg_name = NULL;
  88         msg.msg_namelen = 0;
  89         if (buffer != NULL) {
  90                 iov = ((struct iovec) { buffer, buffer_len });
  91                 msg.msg_iov = &iov;
  92                 msg.msg_iovlen = 1;
  93         }
  94         else {
  95                 msg.msg_iov = NULL;
  96                 msg.msg_iovlen = 0;
  97         }
  98         msg.msg_control = buf;
  99         msg.msg_controllen = sizeof(buf);
 100         msg.msg_flags = 0;
 101         n = recvmsg(me, &msg, 0);
 102         *used_out = n;
 103         if (n < 0) {
 104                 err = -errno;
 105                 printk(UM_KERN_ERR "tuntap_open_tramp : recvmsg failed - "
 106                        "errno = %d\n", errno);
 107                 return err;
 108         }
 109         helper_wait(pid);
 110
 111         cmsg = CMSG_FIRSTHDR(&msg);
 112         if (cmsg == NULL) {
 113                 printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
 114                        "message\n");
 115                 return -EINVAL;
 116         }
 117         if ((cmsg->cmsg_level != SOL_SOCKET) ||
 118            (cmsg->cmsg_type != SCM_RIGHTS)) {
 119                 printk(UM_KERN_ERR "tuntap_open_tramp : didn't receive a "
 120                        "descriptor\n");
 121                 return -EINVAL;
 122         }
 123         *fd_out = ((int *) CMSG_DATA(cmsg))[0];
 124         os_set_exec_close(*fd_out);
 125         return 0;
 126 }
 127
 128 static int tuntap_open(void *data)
 129 {
 130         struct ifreq ifr;
 131         struct tuntap_data *pri = data;
 132         char *output, *buffer;
 133         int err, fds[2], len, used;
 134
 135         err = tap_open_common(pri->dev, pri->gate_addr);
 136         if (err < 0)
 137                 return err;
 138
 139         if (pri->fixed_config) {
 140                 pri->fd = os_open_file("/dev/net/tun",
 141                                        of_cloexec(of_rdwr(OPENFLAGS())), 0);
 142                 if (pri->fd < 0) {
 143                         printk(UM_KERN_ERR "Failed to open /dev/net/tun, "
 144                                "err = %d\n", -pri->fd);
 145                         return pri->fd;
 146                 }
 147                 memset(&ifr, 0, sizeof(ifr));
 148                 ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
 149                 strscpy(ifr.ifr_name, pri->dev_name, sizeof(ifr.ifr_name));
 150                 if (ioctl(pri->fd, TUNSETIFF, &ifr) < 0) {
 151                         err = -errno;
 152                         printk(UM_KERN_ERR "TUNSETIFF failed, errno = %d\n",
 153                                errno);
 154                         close(pri->fd);
 155                         return err;
 156                 }
 157         }
 158         else {
 159                 err = socketpair(AF_UNIX, SOCK_DGRAM, 0, fds);
 160                 if (err) {
 161                         err = -errno;
 162                         printk(UM_KERN_ERR "tuntap_open : socketpair failed - "
 163                                "errno = %d\n", errno);
 164                         return err;
 165                 }
 166
 167                 buffer = get_output_buffer(&len);
 168                 if (buffer != NULL)
 169                         len--;
 170                 used = 0;
 171
 172                 err = tuntap_open_tramp(pri->gate_addr, &pri->fd, fds[0],
 173                                         fds[1], buffer, len, &used);
 174
 175                 output = buffer;
 176                 if (err < 0) {
 177                         printk("%s", output);
 178                         free_output_buffer(buffer);
 179                         printk(UM_KERN_ERR "tuntap_open_tramp failed - "
 180                                "err = %d\n", -err);
 181                         return err;
 182                 }
 183
 184                 pri->dev_name = uml_strdup(buffer);
 185                 output += IFNAMSIZ;
 186                 printk("%s", output);
 187                 free_output_buffer(buffer);
 188
 189                 close(fds[0]);
 190                 iter_addresses(pri->dev, open_addr, pri->dev_name);
 191         }
 192
 193         return pri->fd;
 194 }
 195
 196 static void tuntap_close(int fd, void *data)
 197 {
 198         struct tuntap_data *pri = data;
 199
 200         if (!pri->fixed_config)
 201                 iter_addresses(pri->dev, close_addr, pri->dev_name);
 202         close(fd);
 203         pri->fd = -1;
 204 }
 205
 206 const struct net_user_info tuntap_user_info = {
 207         .init           = tuntap_user_init,
 208         .open           = tuntap_open,
 209         .close          = tuntap_close,
 210         .remove         = NULL,
 211         .add_address    = tuntap_add_addr,
 212         .delete_address = tuntap_del_addr,
 213         .mtu            = ETH_MAX_PACKET,
 214         .max_packet     = ETH_MAX_PACKET + ETH_HEADER_OTHER,
 215 };