mdw@git.distorted.org.uk Git - secnet/blob - tun.c

   1 #include "secnet.h"
   2 #include "util.h"
   3 #include "netlink.h"
   4 #include <stdio.h>
   5 #include <string.h>
   6 #include <unistd.h>
   7 #include <fcntl.h>
   8 #include <sys/ioctl.h>
   9
  10 #ifdef HAVE_LINUX_IF_H
  11 #include <linux/if.h>
  12 #include <linux/if_tun.h>
  13 #endif
  14
  15 /* Where do we find if_tun on other platforms? */
  16
  17 /* Connection to the kernel through the universal TUN/TAP driver */
  18
  19 struct tun {
  20     struct netlink nl;
  21     int fd;
  22     string_t device_path;
  23     string_t interface_name;
  24     string_t ifconfig_path;
  25     string_t route_path;
  26     bool_t tun_old;
  27     bool_t search_for_if; /* Applies to tun-old only */
  28     struct buffer_if *buff; /* We receive packets into here
  29                                and send them to the netlink code. */
  30     netlink_deliver_fn *netlink_to_tunnel;
  31     uint32_t local_address; /* host interface address */
  32 };
  33
  34 static int tun_beforepoll(void *sst, struct pollfd *fds, int *nfds_io,
  35                           int *timeout_io, const struct timeval *tv_now,
  36                           uint64_t *now)
  37 {
  38     struct tun *st=sst;
  39     *nfds_io=1;
  40     fds[0].fd=st->fd;
  41     fds[0].events=POLLIN|POLLERR|POLLHUP;
  42     return 0;
  43 }
  44
  45 static void tun_afterpoll(void *sst, struct pollfd *fds, int nfds,
  46                             const struct timeval *tv_now, uint64_t *now)
  47 {
  48     struct tun *st=sst;
  49     int l;
  50
  51     if (nfds==0) return;
  52     if (fds[0].revents&POLLERR) {
  53         printf("tun_afterpoll: hup!\n");
  54     }
  55     if (fds[0].revents&POLLIN) {
  56         BUF_ALLOC(st->buff,"tun_afterpoll");
  57         buffer_init(st->buff,st->nl.max_start_pad);
  58         l=read(st->fd,st->buff->start,st->buff->len-st->nl.max_start_pad);
  59         if (l<0) {
  60             fatal_perror("tun_afterpoll: read()");
  61         }
  62         if (l==0) {
  63             fatal("tun_afterpoll: read()=0; device gone away?\n");
  64         }
  65         if (l>0) {
  66             st->buff->size=l;
  67             st->netlink_to_tunnel(&st->nl,st->buff);
  68             BUF_ASSERT_FREE(st->buff);
  69         }
  70     }
  71 }
  72
  73 static void tun_deliver_to_kernel(void *sst, struct buffer_if *buf)
  74 {
  75     struct tun *st=sst;
  76
  77     BUF_ASSERT_USED(buf);
  78     /* No error checking, because we'd just throw the packet away
  79        anyway if it didn't work. */
  80     write(st->fd,buf->start,buf->size);
  81     BUF_FREE(buf);
  82 }
  83
  84 static bool_t tun_set_route(void *sst, struct netlink_client *routes)
  85 {
  86     struct tun *st=sst;
  87     string_t network, mask, secnetaddr;
  88     struct subnet_list *nets;
  89     uint32_t i;
  90
  91     if (routes->up != routes->kup) {
  92         nets=routes->subnets;
  93         for (i=0; i<nets->entries; i++) {
  94             network=ipaddr_to_string(nets->list[i].prefix);
  95             mask=ipaddr_to_string(nets->list[i].mask);
  96             secnetaddr=ipaddr_to_string(st->nl.secnet_address);
  97             Message(M_INFO,"%s: %s route %s/%d %s kernel routing table\n",
  98                     st->nl.name,routes->up?"adding":"deleting",network,
  99                     nets->list[i].len,routes->up?"to":"from");
 100             sys_cmd(st->route_path,"route",routes->up?"add":"del",
 101                     "-net",network,"netmask",mask,"gw",secnetaddr,(char *)0);
 102             free(network); free(mask); free(secnetaddr);
 103         }
 104         routes->kup=routes->up;
 105         return True;
 106     }
 107     return False;
 108 }
 109
 110 static void tun_phase_hook(void *sst, uint32_t newphase)
 111 {
 112     struct tun *st=sst;
 113     string_t hostaddr,secnetaddr;
 114     uint8_t mtu[6];
 115     struct netlink_client *r;
 116
 117     if (st->tun_old) {
 118         if (st->search_for_if) {
 119             string_t dname;
 120             int i;
 121
 122             /* ASSERT st->interface_name */
 123             dname=safe_malloc(strlen(st->device_path)+4,"tun_old_apply");
 124             st->interface_name=safe_malloc(8,"tun_phase_hook");
 125
 126             for (i=0; i<255; i++) {
 127                 sprintf(dname,"%s%d",st->device_path,i);
 128                 if ((st->fd=open(dname,O_RDWR))>0) {
 129                     sprintf(st->interface_name,"tun%d",i);
 130                     Message(M_INFO,"%s: allocated network interface %s "
 131                             "through %s\n",st->nl.name,st->interface_name,
 132                             dname);
 133                     break;
 134                 }
 135             }
 136             if (st->fd==-1) {
 137                 fatal("%s: unable to open any TUN device (%s...)\n",
 138                       st->nl.name,st->device_path);
 139             }
 140         } else {
 141             st->fd=open(st->device_path,O_RDWR);
 142             if (st->fd==-1) {
 143                 fatal_perror("%s: unable to open TUN device file %s",
 144                              st->nl.name,st->device_path);
 145             }
 146         }
 147     } else {
 148 #ifdef HAVE_LINUX_IF_H
 149         struct ifreq ifr;
 150
 151         /* New TUN interface: open the device, then do ioctl TUNSETIFF
 152            to set or find out the network interface name. */
 153         st->fd=open(st->device_path,O_RDWR);
 154         if (st->fd==-1) {
 155             fatal_perror("%s: can't open device file %s",st->nl.name,
 156                          st->device_path);
 157         }
 158         memset(&ifr,0,sizeof(ifr));
 159         ifr.ifr_flags = IFF_TUN | IFF_NO_PI; /* Just send/receive IP packets,
 160                                                 no extra headers */
 161         if (st->interface_name)
 162             strncpy(ifr.ifr_name,st->interface_name,IFNAMSIZ);
 163         Message(M_DEBUG,"%s: about to ioctl(TUNSETIFF)...\n",st->nl.name);
 164         if (ioctl(st->fd,TUNSETIFF,&ifr)<0) {
 165             fatal_perror("%s: ioctl(TUNSETIFF)",st->nl.name);
 166         }
 167         if (!st->interface_name) {
 168             st->interface_name=safe_malloc(strlen(ifr.ifr_name)+1,"tun_apply");
 169             strcpy(st->interface_name,ifr.ifr_name);
 170             Message(M_INFO,"%s: allocated network interface %s\n",st->nl.name,
 171                     st->interface_name);
 172         }
 173 #else
 174         fatal("netlink.c:tun_phase_hook:!tun_old unexpected\n");
 175 #endif /* HAVE_LINUX_IF_H */
 176     }
 177     /* All the networks we'll be using have been registered. Invoke ifconfig
 178        to set the TUN device's address, and route to add routes to all
 179        our networks. */
 180
 181     hostaddr=ipaddr_to_string(st->local_address);
 182     secnetaddr=ipaddr_to_string(st->nl.secnet_address);
 183     snprintf(mtu,6,"%d",st->nl.mtu);
 184     mtu[5]=0;
 185
 186     /* XXX on FreeBSD the "-broadcast" and "pointopoint" must be left
 187        out. It assumes a point-to-point interface if two IP addresses
 188        are specified. */
 189     sys_cmd(st->ifconfig_path,"ifconfig",st->interface_name,
 190             hostaddr,"netmask","255.255.255.255","-broadcast",
 191             "pointopoint",secnetaddr,"mtu",mtu,"up",(char *)0);
 192
 193     for (r=st->nl.clients; r; r=r->next) {
 194         tun_set_route(st,r);
 195     }
 196
 197     /* Register for poll() */
 198     register_for_poll(st, tun_beforepoll, tun_afterpoll, 1, st->nl.name);
 199 }
 200
 201 #ifdef HAVE_LINUX_IF_H
 202 static list_t *tun_apply(closure_t *self, struct cloc loc, dict_t *context,
 203                          list_t *args)
 204 {
 205     struct tun *st;
 206     item_t *item;
 207     dict_t *dict;
 208
 209     st=safe_malloc(sizeof(*st),"tun_apply");
 210
 211     /* First parameter must be a dict */
 212     item=list_elem(args,0);
 213     if (!item || item->type!=t_dict)
 214         cfgfatal(loc,"tun","parameter must be a dictionary\n");
 215
 216     dict=item->data.dict;
 217
 218     st->netlink_to_tunnel=
 219         netlink_init(&st->nl,st,loc,dict,
 220                      "netlink-tun",tun_set_route,tun_deliver_to_kernel);
 221
 222     st->tun_old=False;
 223     st->device_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
 224     st->interface_name=dict_read_string(dict,"interface",False,
 225                                         "tun-netlink",loc);
 226     st->ifconfig_path=dict_read_string(dict,"ifconfig-path",
 227                                        False,"tun-netlink",loc);
 228     st->route_path=dict_read_string(dict,"route-path",
 229                                     False,"tun-netlink",loc);
 230
 231     if (!st->device_path) st->device_path="/dev/net/tun";
 232     if (!st->ifconfig_path) st->ifconfig_path="ifconfig";
 233     if (!st->route_path) st->route_path="route";
 234     st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"tun-netlink",loc);
 235     st->local_address=string_item_to_ipaddr(
 236         dict_find_item(dict,"local-address", True, "netlink", loc),"netlink");
 237
 238     add_hook(PHASE_GETRESOURCES,tun_phase_hook,st);
 239
 240     return new_closure(&st->nl.cl);
 241 }
 242 #endif /* HAVE_LINUX_IF_H */
 243
 244 static list_t *tun_old_apply(closure_t *self, struct cloc loc, dict_t *context,
 245                              list_t *args)
 246 {
 247     struct tun *st;
 248     item_t *item;
 249     dict_t *dict;
 250
 251     st=safe_malloc(sizeof(*st),"tun_old_apply");
 252
 253     /* First parameter must be a dict */
 254     item=list_elem(args,0);
 255     if (!item || item->type!=t_dict)
 256         cfgfatal(loc,"tun","parameter must be a dictionary\n");
 257
 258     dict=item->data.dict;
 259
 260     st->netlink_to_tunnel=
 261         netlink_init(&st->nl,st,loc,dict,
 262                      "netlink-tun",tun_set_route,tun_deliver_to_kernel);
 263
 264     st->tun_old=True;
 265     st->device_path=dict_read_string(dict,"device",False,"tun-netlink",loc);
 266     st->interface_name=dict_read_string(dict,"interface",False,
 267                                         "tun-netlink",loc);
 268     st->search_for_if=dict_read_bool(dict,"interface-search",False,
 269                                      "tun-netlink",loc,st->device_path==NULL);
 270     st->ifconfig_path=dict_read_string(dict,"ifconfig-path",False,
 271                                        "tun-netlink",loc);
 272     st->route_path=dict_read_string(dict,"route-path",False,"tun-netlink",loc);
 273
 274     if (!st->device_path) st->device_path="/dev/tun";
 275     if (!st->ifconfig_path) st->ifconfig_path="ifconfig";
 276     if (!st->route_path) st->route_path="route";
 277     st->buff=find_cl_if(dict,"buffer",CL_BUFFER,True,"tun-netlink",loc);
 278     st->local_address=string_item_to_ipaddr(
 279         dict_find_item(dict,"local-address", True, "netlink", loc),"netlink");
 280
 281     /* Old TUN interface: the network interface name depends on which
 282        /dev/tunX file we open. If 'interface-search' is set to true, treat
 283        'device' as the prefix and try numbers from 0--255. If it's set
 284        to false, treat 'device' as the whole name, and require than an
 285        appropriate interface name be specified. */
 286     if (st->search_for_if && st->interface_name) {
 287         cfgfatal(loc,"tun-old","you may not specify an interface name "
 288                  "in interface-search mode\n");
 289     }
 290     if (!st->search_for_if && !st->interface_name) {
 291         cfgfatal(loc,"tun-old","you must specify an interface name "
 292                  "when you explicitly specify a TUN device file\n");
 293     }
 294
 295
 296     add_hook(PHASE_GETRESOURCES,tun_phase_hook,st);
 297
 298     return new_closure(&st->nl.cl);
 299 }
 300
 301 init_module tun_module;
 302 void tun_module(dict_t *dict)
 303 {
 304 #ifdef HAVE_LINUX_IF_H
 305     add_closure(dict,"tun",tun_apply);
 306 #endif
 307     add_closure(dict,"tun-old",tun_old_apply);
 308 }