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/errno.h>
  28 #include <linux/init.h>
  29 #include <net/dst.h>
  30 #include <net/arp.h>
  31 #include <net/sock.h>
  32 #include <net/ipv6.h>
  33 #include <net/ip.h>
  34 #include <asm/uaccess.h>
  35 #include <asm/system.h>
  36 #include <asm/checksum.h>
  37 #include <linux/divert.h>
  38 #include <linux/sockios.h>
  39
  40 const char sysctl_divert_version[32]="0.46";    /* Current version */
  41
  42 static int __init dv_init(void)
  43 {
  44         return 0;
  45 }
  46 module_init(dv_init);
  47
  48 /*
  49  * Allocate a divert_blk for a device. This must be an ethernet nic.
  50  */
  51 int alloc_divert_blk(struct net_device *dev)
  52 {
  53         int alloc_size = (sizeof(struct divert_blk) + 3) & ~3;
  54
  55         if (dev->type == ARPHRD_ETHER) {
  56                 printk(KERN_DEBUG "divert: allocating divert_blk for %s\n",
  57                        dev->name);
  58
  59                 dev->divert = (struct divert_blk *)
  60                         kmalloc(alloc_size, GFP_KERNEL);
  61                 if (dev->divert == NULL) {
  62                         printk(KERN_DEBUG "divert: unable to allocate divert_blk for %s\n",
  63                                dev->name);
  64                         return -ENOMEM;
  65                 } else {
  66                         memset(dev->divert, 0, sizeof(struct divert_blk));
  67                 }
  68                 dev_hold(dev);
  69         } else {
  70                 printk(KERN_DEBUG "divert: not allocating divert_blk for non-ethernet device %s\n",
  71                        dev->name);
  72
  73                 dev->divert = NULL;
  74         }
  75         return 0;
  76 }
  77
  78 /*
  79  * Free a divert_blk allocated by the above function, if it was
  80  * allocated on that device.
  81  */
  82 void free_divert_blk(struct net_device *dev)
  83 {
  84         if (dev->divert) {
  85                 kfree(dev->divert);
  86                 dev->divert=NULL;
  87                 dev_put(dev);
  88                 printk(KERN_DEBUG "divert: freeing divert_blk for %s\n",
  89                        dev->name);
  90         } else {
  91                 printk(KERN_DEBUG "divert: no divert_blk to free, %s not ethernet\n",
  92                        dev->name);
  93         }
  94 }
  95
  96 /*
  97  * Adds a tcp/udp (source or dest) port to an array
  98  */
  99 static int add_port(u16 ports[], u16 port)
 100 {
 101         int i;
 102
 103         if (port == 0)
 104                 return -EINVAL;
 105
 106         /* Storing directly in network format for performance,
 107          * thanks Dave :)
 108          */
 109         port = htons(port);
 110
 111         for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 112                 if (ports[i] == port)
 113                         return -EALREADY;
 114         }
 115
 116         for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 117                 if (ports[i] == 0) {
 118                         ports[i] = port;
 119                         return 0;
 120                 }
 121         }
 122
 123         return -ENOBUFS;
 124 }
 125
 126 /*
 127  * Removes a port from an array tcp/udp (source or dest)
 128  */
 129 static int remove_port(u16 ports[], u16 port)
 130 {
 131         int i;
 132
 133         if (port == 0)
 134                 return -EINVAL;
 135
 136         /* Storing directly in network format for performance,
 137          * thanks Dave !
 138          */
 139         port = htons(port);
 140
 141         for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 142                 if (ports[i] == port) {
 143                         ports[i] = 0;
 144                         return 0;
 145                 }
 146         }
 147
 148         return -EINVAL;
 149 }
 150
 151 /* Some basic sanity checks on the arguments passed to divert_ioctl() */
 152 static int check_args(struct divert_cf *div_cf, struct net_device **dev)
 153 {
 154         char devname[32];
 155         int ret;
 156
 157         if (dev == NULL)
 158                 return -EFAULT;
 159
 160         /* GETVERSION: all other args are unused */
 161         if (div_cf->cmd == DIVCMD_GETVERSION)
 162                 return 0;
 163
 164         /* Network device index should reasonably be between 0 and 1000 :) */
 165         if (div_cf->dev_index < 0 || div_cf->dev_index > 1000)
 166                 return -EINVAL;
 167
 168         /* Let's try to find the ifname */
 169         sprintf(devname, "eth%d", div_cf->dev_index);
 170         *dev = dev_get_by_name(devname);
 171
 172         /* dev should NOT be null */
 173         if (*dev == NULL)
 174                 return -EINVAL;
 175
 176         ret = 0;
 177
 178         /* user issuing the ioctl must be a super one :) */
 179         if (!capable(CAP_SYS_ADMIN)) {
 180                 ret = -EPERM;
 181                 goto out;
 182         }
 183
 184         /* Device must have a divert_blk member NOT null */
 185         if ((*dev)->divert == NULL)
 186                 ret = -EINVAL;
 187 out:
 188         dev_put(*dev);
 189         return ret;
 190 }
 191
 192 /*
 193  * control function of the diverter
 194  */
 195 #define DVDBG(a)        \
 196         printk(KERN_DEBUG "divert_ioctl() line %d %s\n", __LINE__, (a))
 197
 198 int divert_ioctl(unsigned int cmd, struct divert_cf __user *arg)
 199 {
 200         struct divert_cf        div_cf;
 201         struct divert_blk       *div_blk;
 202         struct net_device       *dev;
 203         int                     ret;
 204
 205         switch (cmd) {
 206         case SIOCGIFDIVERT:
 207                 DVDBG("SIOCGIFDIVERT, copy_from_user");
 208                 if (copy_from_user(&div_cf, arg, sizeof(struct divert_cf)))
 209                         return -EFAULT;
 210                 DVDBG("before check_args");
 211                 ret = check_args(&div_cf, &dev);
 212                 if (ret)
 213                         return ret;
 214                 DVDBG("after checkargs");
 215                 div_blk = dev->divert;
 216
 217                 DVDBG("befre switch()");
 218                 switch (div_cf.cmd) {
 219                 case DIVCMD_GETSTATUS:
 220                         /* Now, just give the user the raw divert block
 221                          * for him to play with :)
 222                          */
 223                         if (copy_to_user(div_cf.arg1.ptr, dev->divert,
 224                                          sizeof(struct divert_blk)))
 225                                 return -EFAULT;
 226                         break;
 227
 228                 case DIVCMD_GETVERSION:
 229                         DVDBG("GETVERSION: checking ptr");
 230                         if (div_cf.arg1.ptr == NULL)
 231                                 return -EINVAL;
 232                         DVDBG("GETVERSION: copying data to userland");
 233                         if (copy_to_user(div_cf.arg1.ptr,
 234                                          sysctl_divert_version, 32))
 235                                 return -EFAULT;
 236                         DVDBG("GETVERSION: data copied");
 237                         break;
 238
 239                 default:
 240                         return -EINVAL;
 241                 }
 242
 243                 break;
 244
 245         case SIOCSIFDIVERT:
 246                 if (copy_from_user(&div_cf, arg, sizeof(struct divert_cf)))
 247                         return -EFAULT;
 248
 249                 ret = check_args(&div_cf, &dev);
 250                 if (ret)
 251                         return ret;
 252
 253                 div_blk = dev->divert;
 254
 255                 switch(div_cf.cmd) {
 256                 case DIVCMD_RESET:
 257                         div_blk->divert = 0;
 258                         div_blk->protos = DIVERT_PROTO_NONE;
 259                         memset(div_blk->tcp_dst, 0,
 260                                MAX_DIVERT_PORTS * sizeof(u16));
 261                         memset(div_blk->tcp_src, 0,
 262                                MAX_DIVERT_PORTS * sizeof(u16));
 263                         memset(div_blk->udp_dst, 0,
 264                                MAX_DIVERT_PORTS * sizeof(u16));
 265                         memset(div_blk->udp_src, 0,
 266                                MAX_DIVERT_PORTS * sizeof(u16));
 267                         return 0;
 268
 269                 case DIVCMD_DIVERT:
 270                         switch(div_cf.arg1.int32) {
 271                         case DIVARG1_ENABLE:
 272                                 if (div_blk->divert)
 273                                         return -EALREADY;
 274                                 div_blk->divert = 1;
 275                                 break;
 276
 277                         case DIVARG1_DISABLE:
 278                                 if (!div_blk->divert)
 279                                         return -EALREADY;
 280                                 div_blk->divert = 0;
 281                                 break;
 282
 283                         default:
 284                                 return -EINVAL;
 285                         }
 286
 287                         break;
 288
 289                 case DIVCMD_IP:
 290                         switch(div_cf.arg1.int32) {
 291                         case DIVARG1_ENABLE:
 292                                 if (div_blk->protos & DIVERT_PROTO_IP)
 293                                         return -EALREADY;
 294                                 div_blk->protos |= DIVERT_PROTO_IP;
 295                                 break;
 296
 297                         case DIVARG1_DISABLE:
 298                                 if (!(div_blk->protos & DIVERT_PROTO_IP))
 299                                         return -EALREADY;
 300                                 div_blk->protos &= ~DIVERT_PROTO_IP;
 301                                 break;
 302
 303                         default:
 304                                 return -EINVAL;
 305                         }
 306
 307                         break;
 308
 309                 case DIVCMD_TCP:
 310                         switch(div_cf.arg1.int32) {
 311                         case DIVARG1_ENABLE:
 312                                 if (div_blk->protos & DIVERT_PROTO_TCP)
 313                                         return -EALREADY;
 314                                 div_blk->protos |= DIVERT_PROTO_TCP;
 315                                 break;
 316
 317                         case DIVARG1_DISABLE:
 318                                 if (!(div_blk->protos & DIVERT_PROTO_TCP))
 319                                         return -EALREADY;
 320                                 div_blk->protos &= ~DIVERT_PROTO_TCP;
 321                                 break;
 322
 323                         default:
 324                                 return -EINVAL;
 325                         }
 326
 327                         break;
 328
 329                 case DIVCMD_TCPDST:
 330                         switch(div_cf.arg1.int32) {
 331                         case DIVARG1_ADD:
 332                                 return add_port(div_blk->tcp_dst,
 333                                                 div_cf.arg2.uint16);
 334
 335                         case DIVARG1_REMOVE:
 336                                 return remove_port(div_blk->tcp_dst,
 337                                                    div_cf.arg2.uint16);
 338
 339                         default:
 340                                 return -EINVAL;
 341                         }
 342
 343                         break;
 344
 345                 case DIVCMD_TCPSRC:
 346                         switch(div_cf.arg1.int32) {
 347                         case DIVARG1_ADD:
 348                                 return add_port(div_blk->tcp_src,
 349                                                 div_cf.arg2.uint16);
 350
 351                         case DIVARG1_REMOVE:
 352                                 return remove_port(div_blk->tcp_src,
 353                                                    div_cf.arg2.uint16);
 354
 355                         default:
 356                                 return -EINVAL;
 357                         }
 358
 359                         break;
 360
 361                 case DIVCMD_UDP:
 362                         switch(div_cf.arg1.int32) {
 363                         case DIVARG1_ENABLE:
 364                                 if (div_blk->protos & DIVERT_PROTO_UDP)
 365                                         return -EALREADY;
 366                                 div_blk->protos |= DIVERT_PROTO_UDP;
 367                                 break;
 368
 369                         case DIVARG1_DISABLE:
 370                                 if (!(div_blk->protos & DIVERT_PROTO_UDP))
 371                                         return -EALREADY;
 372                                 div_blk->protos &= ~DIVERT_PROTO_UDP;
 373                                 break;
 374
 375                         default:
 376                                 return -EINVAL;
 377                         }
 378
 379                         break;
 380
 381                 case DIVCMD_UDPDST:
 382                         switch(div_cf.arg1.int32) {
 383                         case DIVARG1_ADD:
 384                                 return add_port(div_blk->udp_dst,
 385                                                 div_cf.arg2.uint16);
 386
 387                         case DIVARG1_REMOVE:
 388                                 return remove_port(div_blk->udp_dst,
 389                                                    div_cf.arg2.uint16);
 390
 391                         default:
 392                                 return -EINVAL;
 393                         }
 394
 395                         break;
 396
 397                 case DIVCMD_UDPSRC:
 398                         switch(div_cf.arg1.int32) {
 399                         case DIVARG1_ADD:
 400                                 return add_port(div_blk->udp_src,
 401                                                 div_cf.arg2.uint16);
 402
 403                         case DIVARG1_REMOVE:
 404                                 return remove_port(div_blk->udp_src,
 405                                                    div_cf.arg2.uint16);
 406
 407                         default:
 408                                 return -EINVAL;
 409                         }
 410
 411                         break;
 412
 413                 case DIVCMD_ICMP:
 414                         switch(div_cf.arg1.int32) {
 415                         case DIVARG1_ENABLE:
 416                                 if (div_blk->protos & DIVERT_PROTO_ICMP)
 417                                         return -EALREADY;
 418                                 div_blk->protos |= DIVERT_PROTO_ICMP;
 419                                 break;
 420
 421                         case DIVARG1_DISABLE:
 422                                 if (!(div_blk->protos & DIVERT_PROTO_ICMP))
 423                                         return -EALREADY;
 424                                 div_blk->protos &= ~DIVERT_PROTO_ICMP;
 425                                 break;
 426
 427                         default:
 428                                 return -EINVAL;
 429                         }
 430
 431                         break;
 432
 433                 default:
 434                         return -EINVAL;
 435                 }
 436
 437                 break;
 438
 439         default:
 440                 return -EINVAL;
 441         }
 442
 443         return 0;
 444 }
 445
 446
 447 /*
 448  * Check if packet should have its dest mac address set to the box itself
 449  * for diversion
 450  */
 451
 452 #define ETH_DIVERT_FRAME(skb) \
 453         memcpy(eth_hdr(skb), skb->dev->dev_addr, ETH_ALEN); \
 454         skb->pkt_type=PACKET_HOST
 455
 456 void divert_frame(struct sk_buff *skb)
 457 {
 458         struct ethhdr                   *eth = eth_hdr(skb);
 459         struct iphdr                    *iph;
 460         struct tcphdr                   *tcph;
 461         struct udphdr                   *udph;
 462         struct divert_blk               *divert = skb->dev->divert;
 463         int                             i, src, dst;
 464         unsigned char                   *skb_data_end = skb->data + skb->len;
 465
 466         /* Packet is already aimed at us, return */
 467         if (!memcmp(eth, skb->dev->dev_addr, ETH_ALEN))
 468                 return;
 469
 470         /* proto is not IP, do nothing */
 471         if (eth->h_proto != htons(ETH_P_IP))
 472                 return;
 473
 474         /* Divert all IP frames ? */
 475         if (divert->protos & DIVERT_PROTO_IP) {
 476                 ETH_DIVERT_FRAME(skb);
 477                 return;
 478         }
 479
 480         /* Check for possible (maliciously) malformed IP frame (thanks Dave) */
 481         iph = (struct iphdr *) skb->data;
 482         if (((iph->ihl<<2)+(unsigned char*)(iph)) >= skb_data_end) {
 483                 printk(KERN_INFO "divert: malformed IP packet !\n");
 484                 return;
 485         }
 486
 487         switch (iph->protocol) {
 488         /* Divert all ICMP frames ? */
 489         case IPPROTO_ICMP:
 490                 if (divert->protos & DIVERT_PROTO_ICMP) {
 491                         ETH_DIVERT_FRAME(skb);
 492                         return;
 493                 }
 494                 break;
 495
 496         /* Divert all TCP frames ? */
 497         case IPPROTO_TCP:
 498                 if (divert->protos & DIVERT_PROTO_TCP) {
 499                         ETH_DIVERT_FRAME(skb);
 500                         return;
 501                 }
 502
 503                 /* Check for possible (maliciously) malformed IP
 504                  * frame (thanx Dave)
 505                  */
 506                 tcph = (struct tcphdr *)
 507                         (((unsigned char *)iph) + (iph->ihl<<2));
 508                 if (((unsigned char *)(tcph+1)) >= skb_data_end) {
 509                         printk(KERN_INFO "divert: malformed TCP packet !\n");
 510                         return;
 511                 }
 512
 513                 /* Divert some tcp dst/src ports only ?*/
 514                 for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 515                         dst = divert->tcp_dst[i];
 516                         src = divert->tcp_src[i];
 517                         if ((dst && dst == tcph->dest) ||
 518                             (src && src == tcph->source)) {
 519                                 ETH_DIVERT_FRAME(skb);
 520                                 return;
 521                         }
 522                 }
 523                 break;
 524
 525         /* Divert all UDP frames ? */
 526         case IPPROTO_UDP:
 527                 if (divert->protos & DIVERT_PROTO_UDP) {
 528                         ETH_DIVERT_FRAME(skb);
 529                         return;
 530                 }
 531
 532                 /* Check for possible (maliciously) malformed IP
 533                  * packet (thanks Dave)
 534                  */
 535                 udph = (struct udphdr *)
 536                         (((unsigned char *)iph) + (iph->ihl<<2));
 537                 if (((unsigned char *)(udph+1)) >= skb_data_end) {
 538                         printk(KERN_INFO
 539                                "divert: malformed UDP packet !\n");
 540                         return;
 541                 }
 542
 543                 /* Divert some udp dst/src ports only ? */
 544                 for (i = 0; i < MAX_DIVERT_PORTS; i++) {
 545                         dst = divert->udp_dst[i];
 546                         src = divert->udp_src[i];
 547                         if ((dst && dst == udph->dest) ||
 548                             (src && src == udph->source)) {
 549                                 ETH_DIVERT_FRAME(skb);
 550                                 return;
 551                         }
 552                 }
 553                 break;
 554         }
 555 }