net/core/filter.c

   1 /*
   2  * Linux Socket Filter - Kernel level socket filtering
   3  *
   4  * Author:
   5  *     Jay Schulist <jschlst@samba.org>
   6  *
   7  * Based on the design of:
   8  *     - The Berkeley Packet Filter
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version
  13  * 2 of the License, or (at your option) any later version.
  14  *
  15  * Andi Kleen - Fix a few bad bugs and races.
  16  * Kris Katterjohn - Added many additional checks in sk_chk_filter()
  17  */
  18
  19 #include <linux/module.h>
  20 #include <linux/types.h>
  21 #include <linux/mm.h>
  22 #include <linux/fcntl.h>
  23 #include <linux/socket.h>
  24 #include <linux/in.h>
  25 #include <linux/inet.h>
  26 #include <linux/netdevice.h>
  27 #include <linux/if_packet.h>
  28 #include <linux/gfp.h>
  29 #include <net/ip.h>
  30 #include <net/protocol.h>
  31 #include <net/netlink.h>
  32 #include <linux/skbuff.h>
  33 #include <net/sock.h>
  34 #include <linux/errno.h>
  35 #include <linux/timer.h>
  36 #include <asm/system.h>
  37 #include <asm/uaccess.h>
  38 #include <asm/unaligned.h>
  39 #include <linux/filter.h>
  40 #include <linux/reciprocal_div.h>
  41
  42 enum {
  43         BPF_S_RET_K = 1,
  44         BPF_S_RET_A,
  45         BPF_S_ALU_ADD_K,
  46         BPF_S_ALU_ADD_X,
  47         BPF_S_ALU_SUB_K,
  48         BPF_S_ALU_SUB_X,
  49         BPF_S_ALU_MUL_K,
  50         BPF_S_ALU_MUL_X,
  51         BPF_S_ALU_DIV_X,
  52         BPF_S_ALU_AND_K,
  53         BPF_S_ALU_AND_X,
  54         BPF_S_ALU_OR_K,
  55         BPF_S_ALU_OR_X,
  56         BPF_S_ALU_LSH_K,
  57         BPF_S_ALU_LSH_X,
  58         BPF_S_ALU_RSH_K,
  59         BPF_S_ALU_RSH_X,
  60         BPF_S_ALU_NEG,
  61         BPF_S_LD_W_ABS,
  62         BPF_S_LD_H_ABS,
  63         BPF_S_LD_B_ABS,
  64         BPF_S_LD_W_LEN,
  65         BPF_S_LD_W_IND,
  66         BPF_S_LD_H_IND,
  67         BPF_S_LD_B_IND,
  68         BPF_S_LD_IMM,
  69         BPF_S_LDX_W_LEN,
  70         BPF_S_LDX_B_MSH,
  71         BPF_S_LDX_IMM,
  72         BPF_S_MISC_TAX,
  73         BPF_S_MISC_TXA,
  74         BPF_S_ALU_DIV_K,
  75         BPF_S_LD_MEM,
  76         BPF_S_LDX_MEM,
  77         BPF_S_ST,
  78         BPF_S_STX,
  79         BPF_S_JMP_JA,
  80         BPF_S_JMP_JEQ_K,
  81         BPF_S_JMP_JEQ_X,
  82         BPF_S_JMP_JGE_K,
  83         BPF_S_JMP_JGE_X,
  84         BPF_S_JMP_JGT_K,
  85         BPF_S_JMP_JGT_X,
  86         BPF_S_JMP_JSET_K,
  87         BPF_S_JMP_JSET_X,
  88         /* Ancillary data */
  89         BPF_S_ANC_PROTOCOL,
  90         BPF_S_ANC_PKTTYPE,
  91         BPF_S_ANC_IFINDEX,
  92         BPF_S_ANC_NLATTR,
  93         BPF_S_ANC_NLATTR_NEST,
  94         BPF_S_ANC_MARK,
  95         BPF_S_ANC_QUEUE,
  96         BPF_S_ANC_HATYPE,
  97         BPF_S_ANC_RXHASH,
  98         BPF_S_ANC_CPU,
  99 };
 100
 101 /* No hurry in this branch */
 102 static void *__load_pointer(const struct sk_buff *skb, int k, unsigned int size)
 103 {
 104         u8 *ptr = NULL;
 105
 106         if (k >= SKF_NET_OFF)
 107                 ptr = skb_network_header(skb) + k - SKF_NET_OFF;
 108         else if (k >= SKF_LL_OFF)
 109                 ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
 110
 111         if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
 112                 return ptr;
 113         return NULL;
 114 }
 115
 116 static inline void *load_pointer(const struct sk_buff *skb, int k,
 117                                  unsigned int size, void *buffer)
 118 {
 119         if (k >= 0)
 120                 return skb_header_pointer(skb, k, size, buffer);
 121         return __load_pointer(skb, k, size);
 122 }
 123
 124 /**
 125  *      sk_filter - run a packet through a socket filter
 126  *      @sk: sock associated with &sk_buff
 127  *      @skb: buffer to filter
 128  *
 129  * Run the filter code and then cut skb->data to correct size returned by
 130  * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
 131  * than pkt_len we keep whole skb->data. This is the socket level
 132  * wrapper to sk_run_filter. It returns 0 if the packet should
 133  * be accepted or -EPERM if the packet should be tossed.
 134  *
 135  */
 136 int sk_filter(struct sock *sk, struct sk_buff *skb)
 137 {
 138         int err;
 139         struct sk_filter *filter;
 140
 141         err = security_sock_rcv_skb(sk, skb);
 142         if (err)
 143                 return err;
 144
 145         rcu_read_lock();
 146         filter = rcu_dereference(sk->sk_filter);
 147         if (filter) {
 148                 unsigned int pkt_len = sk_run_filter(skb, filter->insns);
 149
 150                 err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
 151         }
 152         rcu_read_unlock();
 153
 154         return err;
 155 }
 156 EXPORT_SYMBOL(sk_filter);
 157
 158 /**
 159  *      sk_run_filter - run a filter on a socket
 160  *      @skb: buffer to run the filter on
 161  *      @fentry: filter to apply
 162  *
 163  * Decode and apply filter instructions to the skb->data.
 164  * Return length to keep, 0 for none. @skb is the data we are
 165  * filtering, @filter is the array of filter instructions.
 166  * Because all jumps are guaranteed to be before last instruction,
 167  * and last instruction guaranteed to be a RET, we dont need to check
 168  * flen. (We used to pass to this function the length of filter)
 169  */
 170 unsigned int sk_run_filter(const struct sk_buff *skb,
 171                            const struct sock_filter *fentry)
 172 {
 173         void *ptr;
 174         u32 A = 0;                      /* Accumulator */
 175         u32 X = 0;                      /* Index Register */
 176         u32 mem[BPF_MEMWORDS];          /* Scratch Memory Store */
 177         u32 tmp;
 178         int k;
 179
 180         /*
 181          * Process array of filter instructions.
 182          */
 183         for (;; fentry++) {
 184 #if defined(CONFIG_X86_32)
 185 #define K (fentry->k)
 186 #else
 187                 const u32 K = fentry->k;
 188 #endif
 189
 190                 switch (fentry->code) {
 191                 case BPF_S_ALU_ADD_X:
 192                         A += X;
 193                         continue;
 194                 case BPF_S_ALU_ADD_K:
 195                         A += K;
 196                         continue;
 197                 case BPF_S_ALU_SUB_X:
 198                         A -= X;
 199                         continue;
 200                 case BPF_S_ALU_SUB_K:
 201                         A -= K;
 202                         continue;
 203                 case BPF_S_ALU_MUL_X:
 204                         A *= X;
 205                         continue;
 206                 case BPF_S_ALU_MUL_K:
 207                         A *= K;
 208                         continue;
 209                 case BPF_S_ALU_DIV_X:
 210                         if (X == 0)
 211                                 return 0;
 212                         A /= X;
 213                         continue;
 214                 case BPF_S_ALU_DIV_K:
 215                         A = reciprocal_divide(A, K);
 216                         continue;
 217                 case BPF_S_ALU_AND_X:
 218                         A &= X;
 219                         continue;
 220                 case BPF_S_ALU_AND_K:
 221                         A &= K;
 222                         continue;
 223                 case BPF_S_ALU_OR_X:
 224                         A |= X;
 225                         continue;
 226                 case BPF_S_ALU_OR_K:
 227                         A |= K;
 228                         continue;
 229                 case BPF_S_ALU_LSH_X:
 230                         A <<= X;
 231                         continue;
 232                 case BPF_S_ALU_LSH_K:
 233                         A <<= K;
 234                         continue;
 235                 case BPF_S_ALU_RSH_X:
 236                         A >>= X;
 237                         continue;
 238                 case BPF_S_ALU_RSH_K:
 239                         A >>= K;
 240                         continue;
 241                 case BPF_S_ALU_NEG:
 242                         A = -A;
 243                         continue;
 244                 case BPF_S_JMP_JA:
 245                         fentry += K;
 246                         continue;
 247                 case BPF_S_JMP_JGT_K:
 248                         fentry += (A > K) ? fentry->jt : fentry->jf;
 249                         continue;
 250                 case BPF_S_JMP_JGE_K:
 251                         fentry += (A >= K) ? fentry->jt : fentry->jf;
 252                         continue;
 253                 case BPF_S_JMP_JEQ_K:
 254                         fentry += (A == K) ? fentry->jt : fentry->jf;
 255                         continue;
 256                 case BPF_S_JMP_JSET_K:
 257                         fentry += (A & K) ? fentry->jt : fentry->jf;
 258                         continue;
 259                 case BPF_S_JMP_JGT_X:
 260                         fentry += (A > X) ? fentry->jt : fentry->jf;
 261                         continue;
 262                 case BPF_S_JMP_JGE_X:
 263                         fentry += (A >= X) ? fentry->jt : fentry->jf;
 264                         continue;
 265                 case BPF_S_JMP_JEQ_X:
 266                         fentry += (A == X) ? fentry->jt : fentry->jf;
 267                         continue;
 268                 case BPF_S_JMP_JSET_X:
 269                         fentry += (A & X) ? fentry->jt : fentry->jf;
 270                         continue;
 271                 case BPF_S_LD_W_ABS:
 272                         k = K;
 273 load_w:
 274                         ptr = load_pointer(skb, k, 4, &tmp);
 275                         if (ptr != NULL) {
 276                                 A = get_unaligned_be32(ptr);
 277                                 continue;
 278                         }
 279                         return 0;
 280                 case BPF_S_LD_H_ABS:
 281                         k = K;
 282 load_h:
 283                         ptr = load_pointer(skb, k, 2, &tmp);
 284                         if (ptr != NULL) {
 285                                 A = get_unaligned_be16(ptr);
 286                                 continue;
 287                         }
 288                         return 0;
 289                 case BPF_S_LD_B_ABS:
 290                         k = K;
 291 load_b:
 292                         ptr = load_pointer(skb, k, 1, &tmp);
 293                         if (ptr != NULL) {
 294                                 A = *(u8 *)ptr;
 295                                 continue;
 296                         }
 297                         return 0;
 298                 case BPF_S_LD_W_LEN:
 299                         A = skb->len;
 300                         continue;
 301                 case BPF_S_LDX_W_LEN:
 302                         X = skb->len;
 303                         continue;
 304                 case BPF_S_LD_W_IND:
 305                         k = X + K;
 306                         goto load_w;
 307                 case BPF_S_LD_H_IND:
 308                         k = X + K;
 309                         goto load_h;
 310                 case BPF_S_LD_B_IND:
 311                         k = X + K;
 312                         goto load_b;
 313                 case BPF_S_LDX_B_MSH:
 314                         ptr = load_pointer(skb, K, 1, &tmp);
 315                         if (ptr != NULL) {
 316                                 X = (*(u8 *)ptr & 0xf) << 2;
 317                                 continue;
 318                         }
 319                         return 0;
 320                 case BPF_S_LD_IMM:
 321                         A = K;
 322                         continue;
 323                 case BPF_S_LDX_IMM:
 324                         X = K;
 325                         continue;
 326                 case BPF_S_LD_MEM:
 327                         A = mem[K];
 328                         continue;
 329                 case BPF_S_LDX_MEM:
 330                         X = mem[K];
 331                         continue;
 332                 case BPF_S_MISC_TAX:
 333                         X = A;
 334                         continue;
 335                 case BPF_S_MISC_TXA:
 336                         A = X;
 337                         continue;
 338                 case BPF_S_RET_K:
 339                         return K;
 340                 case BPF_S_RET_A:
 341                         return A;
 342                 case BPF_S_ST:
 343                         mem[K] = A;
 344                         continue;
 345                 case BPF_S_STX:
 346                         mem[K] = X;
 347                         continue;
 348                 case BPF_S_ANC_PROTOCOL:
 349                         A = ntohs(skb->protocol);
 350                         continue;
 351                 case BPF_S_ANC_PKTTYPE:
 352                         A = skb->pkt_type;
 353                         continue;
 354                 case BPF_S_ANC_IFINDEX:
 355                         if (!skb->dev)
 356                                 return 0;
 357                         A = skb->dev->ifindex;
 358                         continue;
 359                 case BPF_S_ANC_MARK:
 360                         A = skb->mark;
 361                         continue;
 362                 case BPF_S_ANC_QUEUE:
 363                         A = skb->queue_mapping;
 364                         continue;
 365                 case BPF_S_ANC_HATYPE:
 366                         if (!skb->dev)
 367                                 return 0;
 368                         A = skb->dev->type;
 369                         continue;
 370                 case BPF_S_ANC_RXHASH:
 371                         A = skb->rxhash;
 372                         continue;
 373                 case BPF_S_ANC_CPU:
 374                         A = raw_smp_processor_id();
 375                         continue;
 376                 case BPF_S_ANC_NLATTR: {
 377                         struct nlattr *nla;
 378
 379                         if (skb_is_nonlinear(skb))
 380                                 return 0;
 381                         if (A > skb->len - sizeof(struct nlattr))
 382                                 return 0;
 383
 384                         nla = nla_find((struct nlattr *)&skb->data[A],
 385                                        skb->len - A, X);
 386                         if (nla)
 387                                 A = (void *)nla - (void *)skb->data;
 388                         else
 389                                 A = 0;
 390                         continue;
 391                 }
 392                 case BPF_S_ANC_NLATTR_NEST: {
 393                         struct nlattr *nla;
 394
 395                         if (skb_is_nonlinear(skb))
 396                                 return 0;
 397                         if (A > skb->len - sizeof(struct nlattr))
 398                                 return 0;
 399
 400                         nla = (struct nlattr *)&skb->data[A];
 401                         if (nla->nla_len > A - skb->len)
 402                                 return 0;
 403
 404                         nla = nla_find_nested(nla, X);
 405                         if (nla)
 406                                 A = (void *)nla - (void *)skb->data;
 407                         else
 408                                 A = 0;
 409                         continue;
 410                 }
 411                 default:
 412                         WARN_ON(1);
 413                         return 0;
 414                 }
 415         }
 416
 417         return 0;
 418 }
 419 EXPORT_SYMBOL(sk_run_filter);
 420
 421 /*
 422  * Security :
 423  * A BPF program is able to use 16 cells of memory to store intermediate
 424  * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter())
 425  * As we dont want to clear mem[] array for each packet going through
 426  * sk_run_filter(), we check that filter loaded by user never try to read
 427  * a cell if not previously written, and we check all branches to be sure
 428  * a malicious user doesn't try to abuse us.
 429  */
 430 static int check_load_and_stores(struct sock_filter *filter, int flen)
 431 {
 432         u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
 433         int pc, ret = 0;
 434
 435         BUILD_BUG_ON(BPF_MEMWORDS > 16);
 436         masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
 437         if (!masks)
 438                 return -ENOMEM;
 439         memset(masks, 0xff, flen * sizeof(*masks));
 440
 441         for (pc = 0; pc < flen; pc++) {
 442                 memvalid &= masks[pc];
 443
 444                 switch (filter[pc].code) {
 445                 case BPF_S_ST:
 446                 case BPF_S_STX:
 447                         memvalid |= (1 << filter[pc].k);
 448                         break;
 449                 case BPF_S_LD_MEM:
 450                 case BPF_S_LDX_MEM:
 451                         if (!(memvalid & (1 << filter[pc].k))) {
 452                                 ret = -EINVAL;
 453                                 goto error;
 454                         }
 455                         break;
 456                 case BPF_S_JMP_JA:
 457                         /* a jump must set masks on target */
 458                         masks[pc + 1 + filter[pc].k] &= memvalid;
 459                         memvalid = ~0;
 460                         break;
 461                 case BPF_S_JMP_JEQ_K:
 462                 case BPF_S_JMP_JEQ_X:
 463                 case BPF_S_JMP_JGE_K:
 464                 case BPF_S_JMP_JGE_X:
 465                 case BPF_S_JMP_JGT_K:
 466                 case BPF_S_JMP_JGT_X:
 467                 case BPF_S_JMP_JSET_X:
 468                 case BPF_S_JMP_JSET_K:
 469                         /* a jump must set masks on targets */
 470                         masks[pc + 1 + filter[pc].jt] &= memvalid;
 471                         masks[pc + 1 + filter[pc].jf] &= memvalid;
 472                         memvalid = ~0;
 473                         break;
 474                 }
 475         }
 476 error:
 477         kfree(masks);
 478         return ret;
 479 }
 480
 481 /**
 482  *      sk_chk_filter - verify socket filter code
 483  *      @filter: filter to verify
 484  *      @flen: length of filter
 485  *
 486  * Check the user's filter code. If we let some ugly
 487  * filter code slip through kaboom! The filter must contain
 488  * no references or jumps that are out of range, no illegal
 489  * instructions, and must end with a RET instruction.
 490  *
 491  * All jumps are forward as they are not signed.
 492  *
 493  * Returns 0 if the rule set is legal or -EINVAL if not.
 494  */
 495 int sk_chk_filter(struct sock_filter *filter, int flen)
 496 {
 497         /*
 498          * Valid instructions are initialized to non-0.
 499          * Invalid instructions are initialized to 0.
 500          */
 501         static const u8 codes[] = {
 502                 [BPF_ALU|BPF_ADD|BPF_K]  = BPF_S_ALU_ADD_K,
 503                 [BPF_ALU|BPF_ADD|BPF_X]  = BPF_S_ALU_ADD_X,
 504                 [BPF_ALU|BPF_SUB|BPF_K]  = BPF_S_ALU_SUB_K,
 505                 [BPF_ALU|BPF_SUB|BPF_X]  = BPF_S_ALU_SUB_X,
 506                 [BPF_ALU|BPF_MUL|BPF_K]  = BPF_S_ALU_MUL_K,
 507                 [BPF_ALU|BPF_MUL|BPF_X]  = BPF_S_ALU_MUL_X,
 508                 [BPF_ALU|BPF_DIV|BPF_X]  = BPF_S_ALU_DIV_X,
 509                 [BPF_ALU|BPF_AND|BPF_K]  = BPF_S_ALU_AND_K,
 510                 [BPF_ALU|BPF_AND|BPF_X]  = BPF_S_ALU_AND_X,
 511                 [BPF_ALU|BPF_OR|BPF_K]   = BPF_S_ALU_OR_K,
 512                 [BPF_ALU|BPF_OR|BPF_X]   = BPF_S_ALU_OR_X,
 513                 [BPF_ALU|BPF_LSH|BPF_K]  = BPF_S_ALU_LSH_K,
 514                 [BPF_ALU|BPF_LSH|BPF_X]  = BPF_S_ALU_LSH_X,
 515                 [BPF_ALU|BPF_RSH|BPF_K]  = BPF_S_ALU_RSH_K,
 516                 [BPF_ALU|BPF_RSH|BPF_X]  = BPF_S_ALU_RSH_X,
 517                 [BPF_ALU|BPF_NEG]        = BPF_S_ALU_NEG,
 518                 [BPF_LD|BPF_W|BPF_ABS]   = BPF_S_LD_W_ABS,
 519                 [BPF_LD|BPF_H|BPF_ABS]   = BPF_S_LD_H_ABS,
 520                 [BPF_LD|BPF_B|BPF_ABS]   = BPF_S_LD_B_ABS,
 521                 [BPF_LD|BPF_W|BPF_LEN]   = BPF_S_LD_W_LEN,
 522                 [BPF_LD|BPF_W|BPF_IND]   = BPF_S_LD_W_IND,
 523                 [BPF_LD|BPF_H|BPF_IND]   = BPF_S_LD_H_IND,
 524                 [BPF_LD|BPF_B|BPF_IND]   = BPF_S_LD_B_IND,
 525                 [BPF_LD|BPF_IMM]         = BPF_S_LD_IMM,
 526                 [BPF_LDX|BPF_W|BPF_LEN]  = BPF_S_LDX_W_LEN,
 527                 [BPF_LDX|BPF_B|BPF_MSH]  = BPF_S_LDX_B_MSH,
 528                 [BPF_LDX|BPF_IMM]        = BPF_S_LDX_IMM,
 529                 [BPF_MISC|BPF_TAX]       = BPF_S_MISC_TAX,
 530                 [BPF_MISC|BPF_TXA]       = BPF_S_MISC_TXA,
 531                 [BPF_RET|BPF_K]          = BPF_S_RET_K,
 532                 [BPF_RET|BPF_A]          = BPF_S_RET_A,
 533                 [BPF_ALU|BPF_DIV|BPF_K]  = BPF_S_ALU_DIV_K,
 534                 [BPF_LD|BPF_MEM]         = BPF_S_LD_MEM,
 535                 [BPF_LDX|BPF_MEM]        = BPF_S_LDX_MEM,
 536                 [BPF_ST]                 = BPF_S_ST,
 537                 [BPF_STX]                = BPF_S_STX,
 538                 [BPF_JMP|BPF_JA]         = BPF_S_JMP_JA,
 539                 [BPF_JMP|BPF_JEQ|BPF_K]  = BPF_S_JMP_JEQ_K,
 540                 [BPF_JMP|BPF_JEQ|BPF_X]  = BPF_S_JMP_JEQ_X,
 541                 [BPF_JMP|BPF_JGE|BPF_K]  = BPF_S_JMP_JGE_K,
 542                 [BPF_JMP|BPF_JGE|BPF_X]  = BPF_S_JMP_JGE_X,
 543                 [BPF_JMP|BPF_JGT|BPF_K]  = BPF_S_JMP_JGT_K,
 544                 [BPF_JMP|BPF_JGT|BPF_X]  = BPF_S_JMP_JGT_X,
 545                 [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
 546                 [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
 547         };
 548         int pc;
 549
 550         if (flen == 0 || flen > BPF_MAXINSNS)
 551                 return -EINVAL;
 552
 553         /* check the filter code now */
 554         for (pc = 0; pc < flen; pc++) {
 555                 struct sock_filter *ftest = &filter[pc];
 556                 u16 code = ftest->code;
 557
 558                 if (code >= ARRAY_SIZE(codes))
 559                         return -EINVAL;
 560                 code = codes[code];
 561                 if (!code)
 562                         return -EINVAL;
 563                 /* Some instructions need special checks */
 564                 switch (code) {
 565                 case BPF_S_ALU_DIV_K:
 566                         /* check for division by zero */
 567                         if (ftest->k == 0)
 568                                 return -EINVAL;
 569                         ftest->k = reciprocal_value(ftest->k);
 570                         break;
 571                 case BPF_S_LD_MEM:
 572                 case BPF_S_LDX_MEM:
 573                 case BPF_S_ST:
 574                 case BPF_S_STX:
 575                         /* check for invalid memory addresses */
 576                         if (ftest->k >= BPF_MEMWORDS)
 577                                 return -EINVAL;
 578                         break;
 579                 case BPF_S_JMP_JA:
 580                         /*
 581                          * Note, the large ftest->k might cause loops.
 582                          * Compare this with conditional jumps below,
 583                          * where offsets are limited. --ANK (981016)
 584                          */
 585                         if (ftest->k >= (unsigned)(flen-pc-1))
 586                                 return -EINVAL;
 587                         break;
 588                 case BPF_S_JMP_JEQ_K:
 589                 case BPF_S_JMP_JEQ_X:
 590                 case BPF_S_JMP_JGE_K:
 591                 case BPF_S_JMP_JGE_X:
 592                 case BPF_S_JMP_JGT_K:
 593                 case BPF_S_JMP_JGT_X:
 594                 case BPF_S_JMP_JSET_X:
 595                 case BPF_S_JMP_JSET_K:
 596                         /* for conditionals both must be safe */
 597                         if (pc + ftest->jt + 1 >= flen ||
 598                             pc + ftest->jf + 1 >= flen)
 599                                 return -EINVAL;
 600                         break;
 601                 case BPF_S_LD_W_ABS:
 602                 case BPF_S_LD_H_ABS:
 603                 case BPF_S_LD_B_ABS:
 604 #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE:        \
 605                                 code = BPF_S_ANC_##CODE;        \
 606                                 break
 607                         switch (ftest->k) {
 608                         ANCILLARY(PROTOCOL);
 609                         ANCILLARY(PKTTYPE);
 610                         ANCILLARY(IFINDEX);
 611                         ANCILLARY(NLATTR);
 612                         ANCILLARY(NLATTR_NEST);
 613                         ANCILLARY(MARK);
 614                         ANCILLARY(QUEUE);
 615                         ANCILLARY(HATYPE);
 616                         ANCILLARY(RXHASH);
 617                         ANCILLARY(CPU);
 618                         }
 619                 }
 620                 ftest->code = code;
 621         }
 622
 623         /* last instruction must be a RET code */
 624         switch (filter[flen - 1].code) {
 625         case BPF_S_RET_K:
 626         case BPF_S_RET_A:
 627                 return check_load_and_stores(filter, flen);
 628         }
 629         return -EINVAL;
 630 }
 631 EXPORT_SYMBOL(sk_chk_filter);
 632
 633 /**
 634  *      sk_filter_release_rcu - Release a socket filter by rcu_head
 635  *      @rcu: rcu_head that contains the sk_filter to free
 636  */
 637 void sk_filter_release_rcu(struct rcu_head *rcu)
 638 {
 639         struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
 640
 641         kfree(fp);
 642 }
 643 EXPORT_SYMBOL(sk_filter_release_rcu);
 644
 645 /**
 646  *      sk_attach_filter - attach a socket filter
 647  *      @fprog: the filter program
 648  *      @sk: the socket to use
 649  *
 650  * Attach the user's filter code. We first run some sanity checks on
 651  * it to make sure it does not explode on us later. If an error
 652  * occurs or there is insufficient memory for the filter a negative
 653  * errno code is returned. On success the return is zero.
 654  */
 655 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 656 {
 657         struct sk_filter *fp, *old_fp;
 658         unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
 659         int err;
 660
 661         /* Make sure new filter is there and in the right amounts. */
 662         if (fprog->filter == NULL)
 663                 return -EINVAL;
 664
 665         fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
 666         if (!fp)
 667                 return -ENOMEM;
 668         if (copy_from_user(fp->insns, fprog->filter, fsize)) {
 669                 sock_kfree_s(sk, fp, fsize+sizeof(*fp));
 670                 return -EFAULT;
 671         }
 672
 673         atomic_set(&fp->refcnt, 1);
 674         fp->len = fprog->len;
 675
 676         err = sk_chk_filter(fp->insns, fp->len);
 677         if (err) {
 678                 sk_filter_uncharge(sk, fp);
 679                 return err;
 680         }
 681
 682         old_fp = rcu_dereference_protected(sk->sk_filter,
 683                                            sock_owned_by_user(sk));
 684         rcu_assign_pointer(sk->sk_filter, fp);
 685
 686         if (old_fp)
 687                 sk_filter_uncharge(sk, old_fp);
 688         return 0;
 689 }
 690 EXPORT_SYMBOL_GPL(sk_attach_filter);
 691
 692 int sk_detach_filter(struct sock *sk)
 693 {
 694         int ret = -ENOENT;
 695         struct sk_filter *filter;
 696
 697         filter = rcu_dereference_protected(sk->sk_filter,
 698                                            sock_owned_by_user(sk));
 699         if (filter) {
 700                 rcu_assign_pointer(sk->sk_filter, NULL);
 701                 sk_filter_uncharge(sk, filter);
 702                 ret = 0;
 703         }
 704         return ret;
 705 }
 706 EXPORT_SYMBOL_GPL(sk_detach_filter);