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