net/core/dv.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Generic frame diversion
   7  *
   8  * Authors:
   9  *              Benoit LOCHER:  initial integration within the kernel with support for ethernet
  10  *              Dave Miller:    improvement on the code (correctness, performance and source files)
  11  *
  12  */
  13 #include <linux/module.h>
  14 #include <linux/types.h>
  15 #include <linux/kernel.h>
  16 #include <linux/sched.h>
  17 #include <linux/string.h>
  18 #include <linux/mm.h>
  19 #include <linux/socket.h>
  20 #include <linux/in.h>
  21 #include <linux/inet.h>
  22 #include <linux/ip.h>
  23 #include <linux/udp.h>
  24 #include <linux/netdevice.h>
  25 #include <linux/etherdevice.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/capability.h>
  28 #include <linux/errno.h>
  29 #include <linux/init.h>
  30 #include <net/dst.h>
  31 #include <net/arp.h>
  32 #include <net/sock.h>
  33 #include <net/ipv6.h>
  34 #include <net/ip.h>
  35 #include <asm/uaccess.h>
  36 #include <asm/system.h>
  37 #include <asm/checksum.h>
  38 #include <linux/divert.h>
  39 #include <linux/sockios.h>
  40
  41 const char sysctl_divert_version[32]="0.46";    /* Current version */
  42
  43 static int __init dv_init(void)
  44 {
  45         return 0;
  46 }
  47 module_init(dv_init);
  48
  49 /*
  50  * Allocate a divert_blk for a device. This must be an ethernet nic.
  51  */
  52 int alloc_divert_blk(struct net_device *dev)
  53 {
  54         int alloc_size = (sizeof(struct divert_blk) + 3) & ~3;
  55
  56         dev->divert = NULL;
  57         if (dev->type == ARPHRD_ETHER) {
  58                 dev->divert = (struct divert_blk *)
  59                         kmalloc(alloc_size, GFP_KERNEL);
  60                 if (dev->divert == NULL) {
  61                         printk(KERN_INFO "divert: unable to allocate divert_blk for %s\n",
  62                                dev->name);
  63                         return -ENOMEM;
  64                 }
  65
  66                 memset(dev->divert, 0, sizeof(struct divert_blk));
  67                 dev_hold(dev);
  68         }
  69
  70         return 0;
  71 }
  72
  73 /*
  74  * Free a divert_blk allocated by the above function, if it was
  75  * allocated on that device.
  76  */
  77 void free_divert_blk(struct net_device *dev)
  78 {
  79         if (dev->divert) {
  80                 kfree(dev->divert);
  81                 dev->divert=NULL;
  82                 dev_put(dev);
  83         }
  84 }
  85
  86 /*
  87  * Adds a tcp/udp (source or dest) port to an array
  88  */
  89 static int add_port(u16 ports[], u16 port)
  90 {
  91         int i;
  92
  93         if (port == 0)
  94                 return -EINVAL;
  95
  96         /* Storing directly in network format for performance,
  97          * thanks Dave :)
  98          */
  99         port = htons(port);
 100
 101         for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 102                 if (ports[i] == port)
 103                         return -EALREADY;
 104         }
 105
 106         for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 107                 if (ports[i] == 0) {
 108                         ports[i] = port;
 109                         return 0;
 110                 }
 111         }
 112
 113         return -ENOBUFS;
 114 }
 115
 116 /*
 117  * Removes a port from an array tcp/udp (source or dest)
 118  */
 119 static int remove_port(u16 ports[], u16 port)
 120 {
 121         int i;
 122
 123         if (port == 0)
 124                 return -EINVAL;
 125
 126         /* Storing directly in network format for performance,
 127          * thanks Dave !
 128          */
 129         port = htons(port);
 130
 131         for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 132                 if (ports[i] == port) {
 133                         ports[i] = 0;
 134                         return 0;
 135                 }
 136         }
 137
 138         return -EINVAL;
 139 }
 140
 141 /* Some basic sanity checks on the arguments passed to divert_ioctl() */
 142 static int check_args(struct divert_cf *div_cf, struct net_device **dev)
 143 {
 144         char devname[32];
 145         int ret;
 146
 147         if (dev == NULL)
 148                 return -EFAULT;
 149
 150         /* GETVERSION: all other args are unused */
 151         if (div_cf->cmd == DIVCMD_GETVERSION)
 152                 return 0;
 153
 154         /* Network device index should reasonably be between 0 and 1000 :) */
 155         if (div_cf->dev_index < 0 || div_cf->dev_index > 1000)
 156                 return -EINVAL;
 157
 158         /* Let's try to find the ifname */
 159         sprintf(devname, "eth%d", div_cf->dev_index);
 160         *dev = dev_get_by_name(devname);
 161
 162         /* dev should NOT be null */
 163         if (*dev == NULL)
 164                 return -EINVAL;
 165
 166         ret = 0;
 167
 168         /* user issuing the ioctl must be a super one :) */
 169         if (!capable(CAP_SYS_ADMIN)) {
 170                 ret = -EPERM;
 171                 goto out;
 172         }
 173
 174         /* Device must have a divert_blk member NOT null */
 175         if ((*dev)->divert == NULL)
 176                 ret = -EINVAL;
 177 out:
 178         dev_put(*dev);
 179         return ret;
 180 }
 181
 182 /*
 183  * control function of the diverter
 184  */
 185 #if 0
 186 #define DVDBG(a)        \
 187         printk(KERN_DEBUG "divert_ioctl() line %d %s\n", __LINE__, (a))
 188 #else
 189 #define DVDBG(a)
 190 #endif
 191
 192 int divert_ioctl(unsigned int cmd, struct divert_cf __user *arg)
 193 {
 194         struct divert_cf        div_cf;
 195         struct divert_blk       *div_blk;
 196         struct net_device       *dev;
 197         int                     ret;
 198
 199         switch (cmd) {
 200         case SIOCGIFDIVERT:
 201                 DVDBG("SIOCGIFDIVERT, copy_from_user");
 202                 if (copy_from_user(&div_cf, arg, sizeof(struct divert_cf)))
 203                         return -EFAULT;
 204                 DVDBG("before check_args");
 205                 ret = check_args(&div_cf, &dev);
 206                 if (ret)
 207                         return ret;
 208                 DVDBG("after checkargs");
 209                 div_blk = dev->divert;
 210
 211                 DVDBG("befre switch()");
 212                 switch (div_cf.cmd) {
 213                 case DIVCMD_GETSTATUS:
 214                         /* Now, just give the user the raw divert block
 215                          * for him to play with :)
 216                          */
 217                         if (copy_to_user(div_cf.arg1.ptr, dev->divert,
 218                                          sizeof(struct divert_blk)))
 219                                 return -EFAULT;
 220                         break;
 221
 222                 case DIVCMD_GETVERSION:
 223                         DVDBG("GETVERSION: checking ptr");
 224                         if (div_cf.arg1.ptr == NULL)
 225                                 return -EINVAL;
 226                         DVDBG("GETVERSION: copying data to userland");
 227                         if (copy_to_user(div_cf.arg1.ptr,
 228                                          sysctl_divert_version, 32))
 229                                 return -EFAULT;
 230                         DVDBG("GETVERSION: data copied");
 231                         break;
 232
 233                 default:
 234                         return -EINVAL;
 235                 }
 236
 237                 break;
 238
 239         case SIOCSIFDIVERT:
 240                 if (copy_from_user(&div_cf, arg, sizeof(struct divert_cf)))
 241                         return -EFAULT;
 242
 243                 ret = check_args(&div_cf, &dev);
 244                 if (ret)
 245                         return ret;
 246
 247                 div_blk = dev->divert;
 248
 249                 switch(div_cf.cmd) {
 250                 case DIVCMD_RESET:
 251                         div_blk->divert = 0;
 252                         div_blk->protos = DIVERT_PROTO_NONE;
 253                         memset(div_blk->tcp_dst, 0,
 254                                MAX_DIVERT_PORTS * sizeof(u16));
 255                         memset(div_blk->tcp_src, 0,
 256                                MAX_DIVERT_PORTS * sizeof(u16));
 257                         memset(div_blk->udp_dst, 0,
 258                                MAX_DIVERT_PORTS * sizeof(u16));
 259                         memset(div_blk->udp_src, 0,
 260                                MAX_DIVERT_PORTS * sizeof(u16));
 261                         return 0;
 262
 263                 case DIVCMD_DIVERT:
 264                         switch(div_cf.arg1.int32) {
 265                         case DIVARG1_ENABLE:
 266                                 if (div_blk->divert)
 267                                         return -EALREADY;
 268                                 div_blk->divert = 1;
 269                                 break;
 270
 271                         case DIVARG1_DISABLE:
 272                                 if (!div_blk->divert)
 273                                         return -EALREADY;
 274                                 div_blk->divert = 0;
 275                                 break;
 276
 277                         default:
 278                                 return -EINVAL;
 279                         }
 280
 281                         break;
 282
 283                 case DIVCMD_IP:
 284                         switch(div_cf.arg1.int32) {
 285                         case DIVARG1_ENABLE:
 286                                 if (div_blk->protos & DIVERT_PROTO_IP)
 287                                         return -EALREADY;
 288                                 div_blk->protos |= DIVERT_PROTO_IP;
 289                                 break;
 290
 291                         case DIVARG1_DISABLE:
 292                                 if (!(div_blk->protos & DIVERT_PROTO_IP))
 293                                         return -EALREADY;
 294                                 div_blk->protos &= ~DIVERT_PROTO_IP;
 295                                 break;
 296
 297                         default:
 298                                 return -EINVAL;
 299                         }
 300
 301                         break;
 302
 303                 case DIVCMD_TCP:
 304                         switch(div_cf.arg1.int32) {
 305                         case DIVARG1_ENABLE:
 306                                 if (div_blk->protos & DIVERT_PROTO_TCP)
 307                                         return -EALREADY;
 308                                 div_blk->protos |= DIVERT_PROTO_TCP;
 309                                 break;
 310
 311                         case DIVARG1_DISABLE:
 312                                 if (!(div_blk->protos & DIVERT_PROTO_TCP))
 313                                         return -EALREADY;
 314                                 div_blk->protos &= ~DIVERT_PROTO_TCP;
 315                                 break;
 316
 317                         default:
 318                                 return -EINVAL;
 319                         }
 320
 321                         break;
 322
 323                 case DIVCMD_TCPDST:
 324                         switch(div_cf.arg1.int32) {
 325                         case DIVARG1_ADD:
 326                                 return add_port(div_blk->tcp_dst,
 327                                                 div_cf.arg2.uint16);
 328
 329                         case DIVARG1_REMOVE:
 330                                 return remove_port(div_blk->tcp_dst,
 331                                                    div_cf.arg2.uint16);
 332
 333                         default:
 334                                 return -EINVAL;
 335                         }
 336
 337                         break;
 338
 339                 case DIVCMD_TCPSRC:
 340                         switch(div_cf.arg1.int32) {
 341                         case DIVARG1_ADD:
 342                                 return add_port(div_blk->tcp_src,
 343                                                 div_cf.arg2.uint16);
 344
 345                         case DIVARG1_REMOVE:
 346                                 return remove_port(div_blk->tcp_src,
 347                                                    div_cf.arg2.uint16);
 348
 349                         default:
 350                                 return -EINVAL;
 351                         }
 352
 353                         break;
 354
 355                 case DIVCMD_UDP:
 356                         switch(div_cf.arg1.int32) {
 357                         case DIVARG1_ENABLE:
 358                                 if (div_blk->protos & DIVERT_PROTO_UDP)
 359                                         return -EALREADY;
 360                                 div_blk->protos |= DIVERT_PROTO_UDP;
 361                                 break;
 362
 363                         case DIVARG1_DISABLE:
 364                                 if (!(div_blk->protos & DIVERT_PROTO_UDP))
 365                                         return -EALREADY;
 366                                 div_blk->protos &= ~DIVERT_PROTO_UDP;
 367                                 break;
 368
 369                         default:
 370                                 return -EINVAL;
 371                         }
 372
 373                         break;
 374
 375                 case DIVCMD_UDPDST:
 376                         switch(div_cf.arg1.int32) {
 377                         case DIVARG1_ADD:
 378                                 return add_port(div_blk->udp_dst,
 379                                                 div_cf.arg2.uint16);
 380
 381                         case DIVARG1_REMOVE:
 382                                 return remove_port(div_blk->udp_dst,
 383                                                    div_cf.arg2.uint16);
 384
 385                         default:
 386                                 return -EINVAL;
 387                         }
 388
 389                         break;
 390
 391                 case DIVCMD_UDPSRC:
 392                         switch(div_cf.arg1.int32) {
 393                         case DIVARG1_ADD:
 394                                 return add_port(div_blk->udp_src,
 395                                                 div_cf.arg2.uint16);
 396
 397                         case DIVARG1_REMOVE:
 398                                 return remove_port(div_blk->udp_src,
 399                                                    div_cf.arg2.uint16);
 400
 401                         default:
 402                                 return -EINVAL;
 403                         }
 404
 405                         break;
 406
 407                 case DIVCMD_ICMP:
 408                         switch(div_cf.arg1.int32) {
 409                         case DIVARG1_ENABLE:
 410                                 if (div_blk->protos & DIVERT_PROTO_ICMP)
 411                                         return -EALREADY;
 412                                 div_blk->protos |= DIVERT_PROTO_ICMP;
 413                                 break;
 414
 415                         case DIVARG1_DISABLE:
 416                                 if (!(div_blk->protos & DIVERT_PROTO_ICMP))
 417                                         return -EALREADY;
 418                                 div_blk->protos &= ~DIVERT_PROTO_ICMP;
 419                                 break;
 420
 421                         default:
 422                                 return -EINVAL;
 423                         }
 424
 425                         break;
 426
 427                 default:
 428                         return -EINVAL;
 429                 }
 430
 431                 break;
 432
 433         default:
 434                 return -EINVAL;
 435         }
 436
 437         return 0;
 438 }
 439
 440
 441 /*
 442  * Check if packet should have its dest mac address set to the box itself
 443  * for diversion
 444  */
 445
 446 #define ETH_DIVERT_FRAME(skb) \
 447         memcpy(eth_hdr(skb), skb->dev->dev_addr, ETH_ALEN); \
 448         skb->pkt_type=PACKET_HOST
 449
 450 void divert_frame(struct sk_buff *skb)
 451 {
 452         struct ethhdr                   *eth = eth_hdr(skb);
 453         struct iphdr                    *iph;
 454         struct tcphdr                   *tcph;
 455         struct udphdr                   *udph;
 456         struct divert_blk               *divert = skb->dev->divert;
 457         int                             i, src, dst;
 458         unsigned char                   *skb_data_end = skb->data + skb->len;
 459
 460         /* Packet is already aimed at us, return */
 461         if (!compare_ether_addr(eth->h_dest, skb->dev->dev_addr))
 462                 return;
 463
 464         /* proto is not IP, do nothing */
 465         if (eth->h_proto != htons(ETH_P_IP))
 466                 return;
 467
 468         /* Divert all IP frames ? */
 469         if (divert->protos & DIVERT_PROTO_IP) {
 470                 ETH_DIVERT_FRAME(skb);
 471                 return;
 472         }
 473
 474         /* Check for possible (maliciously) malformed IP frame (thanks Dave) */
 475         iph = (struct iphdr *) skb->data;
 476         if (((iph->ihl<<2)+(unsigned char*)(iph)) >= skb_data_end) {
 477                 printk(KERN_INFO "divert: malformed IP packet !\n");
 478                 return;
 479         }
 480
 481         switch (iph->protocol) {
 482         /* Divert all ICMP frames ? */
 483         case IPPROTO_ICMP:
 484                 if (divert->protos & DIVERT_PROTO_ICMP) {
 485                         ETH_DIVERT_FRAME(skb);
 486                         return;
 487                 }
 488                 break;
 489
 490         /* Divert all TCP frames ? */
 491         case IPPROTO_TCP:
 492                 if (divert->protos & DIVERT_PROTO_TCP) {
 493                         ETH_DIVERT_FRAME(skb);
 494                         return;
 495                 }
 496
 497                 /* Check for possible (maliciously) malformed IP
 498                  * frame (thanx Dave)
 499                  */
 500                 tcph = (struct tcphdr *)
 501                         (((unsigned char *)iph) + (iph->ihl<<2));
 502                 if (((unsigned char *)(tcph+1)) >= skb_data_end) {
 503                         printk(KERN_INFO "divert: malformed TCP packet !\n");
 504                         return;
 505                 }
 506
 507                 /* Divert some tcp dst/src ports only ?*/
 508                 for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 509                         dst = divert->tcp_dst[i];
 510                         src = divert->tcp_src[i];
 511                         if ((dst && dst == tcph->dest) ||
 512                             (src && src == tcph->source)) {
 513                                 ETH_DIVERT_FRAME(skb);
 514                                 return;
 515                         }
 516                 }
 517                 break;
 518
 519         /* Divert all UDP frames ? */
 520         case IPPROTO_UDP:
 521                 if (divert->protos & DIVERT_PROTO_UDP) {
 522                         ETH_DIVERT_FRAME(skb);
 523                         return;
 524                 }
 525
 526                 /* Check for possible (maliciously) malformed IP
 527                  * packet (thanks Dave)
 528                  */
 529                 udph = (struct udphdr *)
 530                         (((unsigned char *)iph) + (iph->ihl<<2));
 531                 if (((unsigned char *)(udph+1)) >= skb_data_end) {
 532                         printk(KERN_INFO
 533                                "divert: malformed UDP packet !\n");
 534                         return;
 535                 }
 536
 537                 /* Divert some udp dst/src ports only ? */
 538                 for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 539                         dst = divert->udp_dst[i];
 540                         src = divert->udp_src[i];
 541                         if ((dst && dst == udph->dest) ||
 542                             (src && src == udph->source)) {
 543                                 ETH_DIVERT_FRAME(skb);
 544                                 return;
 545                         }
 546                 }
 547                 break;
 548         }
 549 }