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/uaccess.h>
  37 #include <asm/unaligned.h>
  38 #include <linux/filter.h>
  39 #include <linux/reciprocal_div.h>
  40 #include <linux/ratelimit.h>
  41 #include <linux/seccomp.h>
  42 #include <linux/if_vlan.h>
  43
  44 /* No hurry in this branch
  45  *
  46  * Exported for the bpf jit load helper.
  47  */
  48 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
  49 {
  50         u8 *ptr = NULL;
  51
  52         if (k >= SKF_NET_OFF)
  53                 ptr = skb_network_header(skb) + k - SKF_NET_OFF;
  54         else if (k >= SKF_LL_OFF)
  55                 ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
  56
  57         if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
  58                 return ptr;
  59         return NULL;
  60 }
  61
  62 static inline void *load_pointer(const struct sk_buff *skb, int k,
  63                                  unsigned int size, void *buffer)
  64 {
  65         if (k >= 0)
  66                 return skb_header_pointer(skb, k, size, buffer);
  67         return bpf_internal_load_pointer_neg_helper(skb, k, size);
  68 }
  69
  70 /**
  71  *      sk_filter - run a packet through a socket filter
  72  *      @sk: sock associated with &sk_buff
  73  *      @skb: buffer to filter
  74  *
  75  * Run the filter code and then cut skb->data to correct size returned by
  76  * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
  77  * than pkt_len we keep whole skb->data. This is the socket level
  78  * wrapper to sk_run_filter. It returns 0 if the packet should
  79  * be accepted or -EPERM if the packet should be tossed.
  80  *
  81  */
  82 int sk_filter(struct sock *sk, struct sk_buff *skb)
  83 {
  84         int err;
  85         struct sk_filter *filter;
  86
  87         /*
  88          * If the skb was allocated from pfmemalloc reserves, only
  89          * allow SOCK_MEMALLOC sockets to use it as this socket is
  90          * helping free memory
  91          */
  92         if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
  93                 return -ENOMEM;
  94
  95         err = security_sock_rcv_skb(sk, skb);
  96         if (err)
  97                 return err;
  98
  99         rcu_read_lock();
 100         filter = rcu_dereference(sk->sk_filter);
 101         if (filter) {
 102                 unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
 103
 104                 err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
 105         }
 106         rcu_read_unlock();
 107
 108         return err;
 109 }
 110 EXPORT_SYMBOL(sk_filter);
 111
 112 /**
 113  *      sk_run_filter - run a filter on a socket
 114  *      @skb: buffer to run the filter on
 115  *      @fentry: filter to apply
 116  *
 117  * Decode and apply filter instructions to the skb->data.
 118  * Return length to keep, 0 for none. @skb is the data we are
 119  * filtering, @filter is the array of filter instructions.
 120  * Because all jumps are guaranteed to be before last instruction,
 121  * and last instruction guaranteed to be a RET, we dont need to check
 122  * flen. (We used to pass to this function the length of filter)
 123  */
 124 unsigned int sk_run_filter(const struct sk_buff *skb,
 125                            const struct sock_filter *fentry)
 126 {
 127         void *ptr;
 128         u32 A = 0;                      /* Accumulator */
 129         u32 X = 0;                      /* Index Register */
 130         u32 mem[BPF_MEMWORDS];          /* Scratch Memory Store */
 131         u32 tmp;
 132         int k;
 133
 134         /*
 135          * Process array of filter instructions.
 136          */
 137         for (;; fentry++) {
 138 #if defined(CONFIG_X86_32)
 139 #define K (fentry->k)
 140 #else
 141                 const u32 K = fentry->k;
 142 #endif
 143
 144                 switch (fentry->code) {
 145                 case BPF_S_ALU_ADD_X:
 146                         A += X;
 147                         continue;
 148                 case BPF_S_ALU_ADD_K:
 149                         A += K;
 150                         continue;
 151                 case BPF_S_ALU_SUB_X:
 152                         A -= X;
 153                         continue;
 154                 case BPF_S_ALU_SUB_K:
 155                         A -= K;
 156                         continue;
 157                 case BPF_S_ALU_MUL_X:
 158                         A *= X;
 159                         continue;
 160                 case BPF_S_ALU_MUL_K:
 161                         A *= K;
 162                         continue;
 163                 case BPF_S_ALU_DIV_X:
 164                         if (X == 0)
 165                                 return 0;
 166                         A /= X;
 167                         continue;
 168                 case BPF_S_ALU_DIV_K:
 169                         A = reciprocal_divide(A, K);
 170                         continue;
 171                 case BPF_S_ALU_MOD_X:
 172                         if (X == 0)
 173                                 return 0;
 174                         A %= X;
 175                         continue;
 176                 case BPF_S_ALU_MOD_K:
 177                         A %= K;
 178                         continue;
 179                 case BPF_S_ALU_AND_X:
 180                         A &= X;
 181                         continue;
 182                 case BPF_S_ALU_AND_K:
 183                         A &= K;
 184                         continue;
 185                 case BPF_S_ALU_OR_X:
 186                         A |= X;
 187                         continue;
 188                 case BPF_S_ALU_OR_K:
 189                         A |= K;
 190                         continue;
 191                 case BPF_S_ANC_ALU_XOR_X:
 192                 case BPF_S_ALU_XOR_X:
 193                         A ^= X;
 194                         continue;
 195                 case BPF_S_ALU_XOR_K:
 196                         A ^= K;
 197                         continue;
 198                 case BPF_S_ALU_LSH_X:
 199                         A <<= X;
 200                         continue;
 201                 case BPF_S_ALU_LSH_K:
 202                         A <<= K;
 203                         continue;
 204                 case BPF_S_ALU_RSH_X:
 205                         A >>= X;
 206                         continue;
 207                 case BPF_S_ALU_RSH_K:
 208                         A >>= K;
 209                         continue;
 210                 case BPF_S_ALU_NEG:
 211                         A = -A;
 212                         continue;
 213                 case BPF_S_JMP_JA:
 214                         fentry += K;
 215                         continue;
 216                 case BPF_S_JMP_JGT_K:
 217                         fentry += (A > K) ? fentry->jt : fentry->jf;
 218                         continue;
 219                 case BPF_S_JMP_JGE_K:
 220                         fentry += (A >= K) ? fentry->jt : fentry->jf;
 221                         continue;
 222                 case BPF_S_JMP_JEQ_K:
 223                         fentry += (A == K) ? fentry->jt : fentry->jf;
 224                         continue;
 225                 case BPF_S_JMP_JSET_K:
 226                         fentry += (A & K) ? fentry->jt : fentry->jf;
 227                         continue;
 228                 case BPF_S_JMP_JGT_X:
 229                         fentry += (A > X) ? fentry->jt : fentry->jf;
 230                         continue;
 231                 case BPF_S_JMP_JGE_X:
 232                         fentry += (A >= X) ? fentry->jt : fentry->jf;
 233                         continue;
 234                 case BPF_S_JMP_JEQ_X:
 235                         fentry += (A == X) ? fentry->jt : fentry->jf;
 236                         continue;
 237                 case BPF_S_JMP_JSET_X:
 238                         fentry += (A & X) ? fentry->jt : fentry->jf;
 239                         continue;
 240                 case BPF_S_LD_W_ABS:
 241                         k = K;
 242 load_w:
 243                         ptr = load_pointer(skb, k, 4, &tmp);
 244                         if (ptr != NULL) {
 245                                 A = get_unaligned_be32(ptr);
 246                                 continue;
 247                         }
 248                         return 0;
 249                 case BPF_S_LD_H_ABS:
 250                         k = K;
 251 load_h:
 252                         ptr = load_pointer(skb, k, 2, &tmp);
 253                         if (ptr != NULL) {
 254                                 A = get_unaligned_be16(ptr);
 255                                 continue;
 256                         }
 257                         return 0;
 258                 case BPF_S_LD_B_ABS:
 259                         k = K;
 260 load_b:
 261                         ptr = load_pointer(skb, k, 1, &tmp);
 262                         if (ptr != NULL) {
 263                                 A = *(u8 *)ptr;
 264                                 continue;
 265                         }
 266                         return 0;
 267                 case BPF_S_LD_W_LEN:
 268                         A = skb->len;
 269                         continue;
 270                 case BPF_S_LDX_W_LEN:
 271                         X = skb->len;
 272                         continue;
 273                 case BPF_S_LD_W_IND:
 274                         k = X + K;
 275                         goto load_w;
 276                 case BPF_S_LD_H_IND:
 277                         k = X + K;
 278                         goto load_h;
 279                 case BPF_S_LD_B_IND:
 280                         k = X + K;
 281                         goto load_b;
 282                 case BPF_S_LDX_B_MSH:
 283                         ptr = load_pointer(skb, K, 1, &tmp);
 284                         if (ptr != NULL) {
 285                                 X = (*(u8 *)ptr & 0xf) << 2;
 286                                 continue;
 287                         }
 288                         return 0;
 289                 case BPF_S_LD_IMM:
 290                         A = K;
 291                         continue;
 292                 case BPF_S_LDX_IMM:
 293                         X = K;
 294                         continue;
 295                 case BPF_S_LD_MEM:
 296                         A = mem[K];
 297                         continue;
 298                 case BPF_S_LDX_MEM:
 299                         X = mem[K];
 300                         continue;
 301                 case BPF_S_MISC_TAX:
 302                         X = A;
 303                         continue;
 304                 case BPF_S_MISC_TXA:
 305                         A = X;
 306                         continue;
 307                 case BPF_S_RET_K:
 308                         return K;
 309                 case BPF_S_RET_A:
 310                         return A;
 311                 case BPF_S_ST:
 312                         mem[K] = A;
 313                         continue;
 314                 case BPF_S_STX:
 315                         mem[K] = X;
 316                         continue;
 317                 case BPF_S_ANC_PROTOCOL:
 318                         A = ntohs(skb->protocol);
 319                         continue;
 320                 case BPF_S_ANC_PKTTYPE:
 321                         A = skb->pkt_type;
 322                         continue;
 323                 case BPF_S_ANC_IFINDEX:
 324                         if (!skb->dev)
 325                                 return 0;
 326                         A = skb->dev->ifindex;
 327                         continue;
 328                 case BPF_S_ANC_MARK:
 329                         A = skb->mark;
 330                         continue;
 331                 case BPF_S_ANC_QUEUE:
 332                         A = skb->queue_mapping;
 333                         continue;
 334                 case BPF_S_ANC_HATYPE:
 335                         if (!skb->dev)
 336                                 return 0;
 337                         A = skb->dev->type;
 338                         continue;
 339                 case BPF_S_ANC_RXHASH:
 340                         A = skb->rxhash;
 341                         continue;
 342                 case BPF_S_ANC_CPU:
 343                         A = raw_smp_processor_id();
 344                         continue;
 345                 case BPF_S_ANC_VLAN_TAG:
 346                         A = vlan_tx_tag_get(skb);
 347                         continue;
 348                 case BPF_S_ANC_VLAN_TAG_PRESENT:
 349                         A = !!vlan_tx_tag_present(skb);
 350                         continue;
 351                 case BPF_S_ANC_PAY_OFFSET:
 352                         A = __skb_get_poff(skb);
 353                         continue;
 354                 case BPF_S_ANC_NLATTR: {
 355                         struct nlattr *nla;
 356
 357                         if (skb_is_nonlinear(skb))
 358                                 return 0;
 359                         if (A > skb->len - sizeof(struct nlattr))
 360                                 return 0;
 361
 362                         nla = nla_find((struct nlattr *)&skb->data[A],
 363                                        skb->len - A, X);
 364                         if (nla)
 365                                 A = (void *)nla - (void *)skb->data;
 366                         else
 367                                 A = 0;
 368                         continue;
 369                 }
 370                 case BPF_S_ANC_NLATTR_NEST: {
 371                         struct nlattr *nla;
 372
 373                         if (skb_is_nonlinear(skb))
 374                                 return 0;
 375                         if (A > skb->len - sizeof(struct nlattr))
 376                                 return 0;
 377
 378                         nla = (struct nlattr *)&skb->data[A];
 379                         if (nla->nla_len > A - skb->len)
 380                                 return 0;
 381
 382                         nla = nla_find_nested(nla, X);
 383                         if (nla)
 384                                 A = (void *)nla - (void *)skb->data;
 385                         else
 386                                 A = 0;
 387                         continue;
 388                 }
 389 #ifdef CONFIG_SECCOMP_FILTER
 390                 case BPF_S_ANC_SECCOMP_LD_W:
 391                         A = seccomp_bpf_load(fentry->k);
 392                         continue;
 393 #endif
 394                 default:
 395                         WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n",
 396                                        fentry->code, fentry->jt,
 397                                        fentry->jf, fentry->k);
 398                         return 0;
 399                 }
 400         }
 401
 402         return 0;
 403 }
 404 EXPORT_SYMBOL(sk_run_filter);
 405
 406 /*
 407  * Security :
 408  * A BPF program is able to use 16 cells of memory to store intermediate
 409  * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter())
 410  * As we dont want to clear mem[] array for each packet going through
 411  * sk_run_filter(), we check that filter loaded by user never try to read
 412  * a cell if not previously written, and we check all branches to be sure
 413  * a malicious user doesn't try to abuse us.
 414  */
 415 static int check_load_and_stores(struct sock_filter *filter, int flen)
 416 {
 417         u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
 418         int pc, ret = 0;
 419
 420         BUILD_BUG_ON(BPF_MEMWORDS > 16);
 421         masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
 422         if (!masks)
 423                 return -ENOMEM;
 424         memset(masks, 0xff, flen * sizeof(*masks));
 425
 426         for (pc = 0; pc < flen; pc++) {
 427                 memvalid &= masks[pc];
 428
 429                 switch (filter[pc].code) {
 430                 case BPF_S_ST:
 431                 case BPF_S_STX:
 432                         memvalid |= (1 << filter[pc].k);
 433                         break;
 434                 case BPF_S_LD_MEM:
 435                 case BPF_S_LDX_MEM:
 436                         if (!(memvalid & (1 << filter[pc].k))) {
 437                                 ret = -EINVAL;
 438                                 goto error;
 439                         }
 440                         break;
 441                 case BPF_S_JMP_JA:
 442                         /* a jump must set masks on target */
 443                         masks[pc + 1 + filter[pc].k] &= memvalid;
 444                         memvalid = ~0;
 445                         break;
 446                 case BPF_S_JMP_JEQ_K:
 447                 case BPF_S_JMP_JEQ_X:
 448                 case BPF_S_JMP_JGE_K:
 449                 case BPF_S_JMP_JGE_X:
 450                 case BPF_S_JMP_JGT_K:
 451                 case BPF_S_JMP_JGT_X:
 452                 case BPF_S_JMP_JSET_X:
 453                 case BPF_S_JMP_JSET_K:
 454                         /* a jump must set masks on targets */
 455                         masks[pc + 1 + filter[pc].jt] &= memvalid;
 456                         masks[pc + 1 + filter[pc].jf] &= memvalid;
 457                         memvalid = ~0;
 458                         break;
 459                 }
 460         }
 461 error:
 462         kfree(masks);
 463         return ret;
 464 }
 465
 466 /**
 467  *      sk_chk_filter - verify socket filter code
 468  *      @filter: filter to verify
 469  *      @flen: length of filter
 470  *
 471  * Check the user's filter code. If we let some ugly
 472  * filter code slip through kaboom! The filter must contain
 473  * no references or jumps that are out of range, no illegal
 474  * instructions, and must end with a RET instruction.
 475  *
 476  * All jumps are forward as they are not signed.
 477  *
 478  * Returns 0 if the rule set is legal or -EINVAL if not.
 479  */
 480 int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
 481 {
 482         /*
 483          * Valid instructions are initialized to non-0.
 484          * Invalid instructions are initialized to 0.
 485          */
 486         static const u8 codes[] = {
 487                 [BPF_ALU|BPF_ADD|BPF_K]  = BPF_S_ALU_ADD_K,
 488                 [BPF_ALU|BPF_ADD|BPF_X]  = BPF_S_ALU_ADD_X,
 489                 [BPF_ALU|BPF_SUB|BPF_K]  = BPF_S_ALU_SUB_K,
 490                 [BPF_ALU|BPF_SUB|BPF_X]  = BPF_S_ALU_SUB_X,
 491                 [BPF_ALU|BPF_MUL|BPF_K]  = BPF_S_ALU_MUL_K,
 492                 [BPF_ALU|BPF_MUL|BPF_X]  = BPF_S_ALU_MUL_X,
 493                 [BPF_ALU|BPF_DIV|BPF_X]  = BPF_S_ALU_DIV_X,
 494                 [BPF_ALU|BPF_MOD|BPF_K]  = BPF_S_ALU_MOD_K,
 495                 [BPF_ALU|BPF_MOD|BPF_X]  = BPF_S_ALU_MOD_X,
 496                 [BPF_ALU|BPF_AND|BPF_K]  = BPF_S_ALU_AND_K,
 497                 [BPF_ALU|BPF_AND|BPF_X]  = BPF_S_ALU_AND_X,
 498                 [BPF_ALU|BPF_OR|BPF_K]   = BPF_S_ALU_OR_K,
 499                 [BPF_ALU|BPF_OR|BPF_X]   = BPF_S_ALU_OR_X,
 500                 [BPF_ALU|BPF_XOR|BPF_K]  = BPF_S_ALU_XOR_K,
 501                 [BPF_ALU|BPF_XOR|BPF_X]  = BPF_S_ALU_XOR_X,
 502                 [BPF_ALU|BPF_LSH|BPF_K]  = BPF_S_ALU_LSH_K,
 503                 [BPF_ALU|BPF_LSH|BPF_X]  = BPF_S_ALU_LSH_X,
 504                 [BPF_ALU|BPF_RSH|BPF_K]  = BPF_S_ALU_RSH_K,
 505                 [BPF_ALU|BPF_RSH|BPF_X]  = BPF_S_ALU_RSH_X,
 506                 [BPF_ALU|BPF_NEG]        = BPF_S_ALU_NEG,
 507                 [BPF_LD|BPF_W|BPF_ABS]   = BPF_S_LD_W_ABS,
 508                 [BPF_LD|BPF_H|BPF_ABS]   = BPF_S_LD_H_ABS,
 509                 [BPF_LD|BPF_B|BPF_ABS]   = BPF_S_LD_B_ABS,
 510                 [BPF_LD|BPF_W|BPF_LEN]   = BPF_S_LD_W_LEN,
 511                 [BPF_LD|BPF_W|BPF_IND]   = BPF_S_LD_W_IND,
 512                 [BPF_LD|BPF_H|BPF_IND]   = BPF_S_LD_H_IND,
 513                 [BPF_LD|BPF_B|BPF_IND]   = BPF_S_LD_B_IND,
 514                 [BPF_LD|BPF_IMM]         = BPF_S_LD_IMM,
 515                 [BPF_LDX|BPF_W|BPF_LEN]  = BPF_S_LDX_W_LEN,
 516                 [BPF_LDX|BPF_B|BPF_MSH]  = BPF_S_LDX_B_MSH,
 517                 [BPF_LDX|BPF_IMM]        = BPF_S_LDX_IMM,
 518                 [BPF_MISC|BPF_TAX]       = BPF_S_MISC_TAX,
 519                 [BPF_MISC|BPF_TXA]       = BPF_S_MISC_TXA,
 520                 [BPF_RET|BPF_K]          = BPF_S_RET_K,
 521                 [BPF_RET|BPF_A]          = BPF_S_RET_A,
 522                 [BPF_ALU|BPF_DIV|BPF_K]  = BPF_S_ALU_DIV_K,
 523                 [BPF_LD|BPF_MEM]         = BPF_S_LD_MEM,
 524                 [BPF_LDX|BPF_MEM]        = BPF_S_LDX_MEM,
 525                 [BPF_ST]                 = BPF_S_ST,
 526                 [BPF_STX]                = BPF_S_STX,
 527                 [BPF_JMP|BPF_JA]         = BPF_S_JMP_JA,
 528                 [BPF_JMP|BPF_JEQ|BPF_K]  = BPF_S_JMP_JEQ_K,
 529                 [BPF_JMP|BPF_JEQ|BPF_X]  = BPF_S_JMP_JEQ_X,
 530                 [BPF_JMP|BPF_JGE|BPF_K]  = BPF_S_JMP_JGE_K,
 531                 [BPF_JMP|BPF_JGE|BPF_X]  = BPF_S_JMP_JGE_X,
 532                 [BPF_JMP|BPF_JGT|BPF_K]  = BPF_S_JMP_JGT_K,
 533                 [BPF_JMP|BPF_JGT|BPF_X]  = BPF_S_JMP_JGT_X,
 534                 [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
 535                 [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
 536         };
 537         int pc;
 538         bool anc_found;
 539
 540         if (flen == 0 || flen > BPF_MAXINSNS)
 541                 return -EINVAL;
 542
 543         /* check the filter code now */
 544         for (pc = 0; pc < flen; pc++) {
 545                 struct sock_filter *ftest = &filter[pc];
 546                 u16 code = ftest->code;
 547
 548                 if (code >= ARRAY_SIZE(codes))
 549                         return -EINVAL;
 550                 code = codes[code];
 551                 if (!code)
 552                         return -EINVAL;
 553                 /* Some instructions need special checks */
 554                 switch (code) {
 555                 case BPF_S_ALU_DIV_K:
 556                         /* check for division by zero */
 557                         if (ftest->k == 0)
 558                                 return -EINVAL;
 559                         ftest->k = reciprocal_value(ftest->k);
 560                         break;
 561                 case BPF_S_ALU_MOD_K:
 562                         /* check for division by zero */
 563                         if (ftest->k == 0)
 564                                 return -EINVAL;
 565                         break;
 566                 case BPF_S_LD_MEM:
 567                 case BPF_S_LDX_MEM:
 568                 case BPF_S_ST:
 569                 case BPF_S_STX:
 570                         /* check for invalid memory addresses */
 571                         if (ftest->k >= BPF_MEMWORDS)
 572                                 return -EINVAL;
 573                         break;
 574                 case BPF_S_JMP_JA:
 575                         /*
 576                          * Note, the large ftest->k might cause loops.
 577                          * Compare this with conditional jumps below,
 578                          * where offsets are limited. --ANK (981016)
 579                          */
 580                         if (ftest->k >= (unsigned int)(flen-pc-1))
 581                                 return -EINVAL;
 582                         break;
 583                 case BPF_S_JMP_JEQ_K:
 584                 case BPF_S_JMP_JEQ_X:
 585                 case BPF_S_JMP_JGE_K:
 586                 case BPF_S_JMP_JGE_X:
 587                 case BPF_S_JMP_JGT_K:
 588                 case BPF_S_JMP_JGT_X:
 589                 case BPF_S_JMP_JSET_X:
 590                 case BPF_S_JMP_JSET_K:
 591                         /* for conditionals both must be safe */
 592                         if (pc + ftest->jt + 1 >= flen ||
 593                             pc + ftest->jf + 1 >= flen)
 594                                 return -EINVAL;
 595                         break;
 596                 case BPF_S_LD_W_ABS:
 597                 case BPF_S_LD_H_ABS:
 598                 case BPF_S_LD_B_ABS:
 599                         anc_found = false;
 600 #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE:        \
 601                                 code = BPF_S_ANC_##CODE;        \
 602                                 anc_found = true;               \
 603                                 break
 604                         switch (ftest->k) {
 605                         ANCILLARY(PROTOCOL);
 606                         ANCILLARY(PKTTYPE);
 607                         ANCILLARY(IFINDEX);
 608                         ANCILLARY(NLATTR);
 609                         ANCILLARY(NLATTR_NEST);
 610                         ANCILLARY(MARK);
 611                         ANCILLARY(QUEUE);
 612                         ANCILLARY(HATYPE);
 613                         ANCILLARY(RXHASH);
 614                         ANCILLARY(CPU);
 615                         ANCILLARY(ALU_XOR_X);
 616                         ANCILLARY(VLAN_TAG);
 617                         ANCILLARY(VLAN_TAG_PRESENT);
 618                         ANCILLARY(PAY_OFFSET);
 619                         }
 620
 621                         /* ancillary operation unknown or unsupported */
 622                         if (anc_found == false && ftest->k >= SKF_AD_OFF)
 623                                 return -EINVAL;
 624                 }
 625                 ftest->code = code;
 626         }
 627
 628         /* last instruction must be a RET code */
 629         switch (filter[flen - 1].code) {
 630         case BPF_S_RET_K:
 631         case BPF_S_RET_A:
 632                 return check_load_and_stores(filter, flen);
 633         }
 634         return -EINVAL;
 635 }
 636 EXPORT_SYMBOL(sk_chk_filter);
 637
 638 /**
 639  *      sk_filter_release_rcu - Release a socket filter by rcu_head
 640  *      @rcu: rcu_head that contains the sk_filter to free
 641  */
 642 void sk_filter_release_rcu(struct rcu_head *rcu)
 643 {
 644         struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
 645
 646         bpf_jit_free(fp);
 647 }
 648 EXPORT_SYMBOL(sk_filter_release_rcu);
 649
 650 static int __sk_prepare_filter(struct sk_filter *fp)
 651 {
 652         int err;
 653
 654         fp->bpf_func = sk_run_filter;
 655
 656         err = sk_chk_filter(fp->insns, fp->len);
 657         if (err)
 658                 return err;
 659
 660         bpf_jit_compile(fp);
 661         return 0;
 662 }
 663
 664 /**
 665  *      sk_unattached_filter_create - create an unattached filter
 666  *      @fprog: the filter program
 667  *      @pfp: the unattached filter that is created
 668  *
 669  * Create a filter independent of any socket. We first run some
 670  * sanity checks on it to make sure it does not explode on us later.
 671  * If an error occurs or there is insufficient memory for the filter
 672  * a negative errno code is returned. On success the return is zero.
 673  */
 674 int sk_unattached_filter_create(struct sk_filter **pfp,
 675                                 struct sock_fprog *fprog)
 676 {
 677         struct sk_filter *fp;
 678         unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
 679         int err;
 680
 681         /* Make sure new filter is there and in the right amounts. */
 682         if (fprog->filter == NULL)
 683                 return -EINVAL;
 684
 685         fp = kmalloc(sk_filter_size(fprog->len), GFP_KERNEL);
 686         if (!fp)
 687                 return -ENOMEM;
 688         memcpy(fp->insns, fprog->filter, fsize);
 689
 690         atomic_set(&fp->refcnt, 1);
 691         fp->len = fprog->len;
 692
 693         err = __sk_prepare_filter(fp);
 694         if (err)
 695                 goto free_mem;
 696
 697         *pfp = fp;
 698         return 0;
 699 free_mem:
 700         kfree(fp);
 701         return err;
 702 }
 703 EXPORT_SYMBOL_GPL(sk_unattached_filter_create);
 704
 705 void sk_unattached_filter_destroy(struct sk_filter *fp)
 706 {
 707         sk_filter_release(fp);
 708 }
 709 EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
 710
 711 /**
 712  *      sk_attach_filter - attach a socket filter
 713  *      @fprog: the filter program
 714  *      @sk: the socket to use
 715  *
 716  * Attach the user's filter code. We first run some sanity checks on
 717  * it to make sure it does not explode on us later. If an error
 718  * occurs or there is insufficient memory for the filter a negative
 719  * errno code is returned. On success the return is zero.
 720  */
 721 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
 722 {
 723         struct sk_filter *fp, *old_fp;
 724         unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
 725         unsigned int sk_fsize = sk_filter_size(fprog->len);
 726         int err;
 727
 728         if (sock_flag(sk, SOCK_FILTER_LOCKED))
 729                 return -EPERM;
 730
 731         /* Make sure new filter is there and in the right amounts. */
 732         if (fprog->filter == NULL)
 733                 return -EINVAL;
 734
 735         fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL);
 736         if (!fp)
 737                 return -ENOMEM;
 738         if (copy_from_user(fp->insns, fprog->filter, fsize)) {
 739                 sock_kfree_s(sk, fp, sk_fsize);
 740                 return -EFAULT;
 741         }
 742
 743         atomic_set(&fp->refcnt, 1);
 744         fp->len = fprog->len;
 745
 746         err = __sk_prepare_filter(fp);
 747         if (err) {
 748                 sk_filter_uncharge(sk, fp);
 749                 return err;
 750         }
 751
 752         old_fp = rcu_dereference_protected(sk->sk_filter,
 753                                            sock_owned_by_user(sk));
 754         rcu_assign_pointer(sk->sk_filter, fp);
 755
 756         if (old_fp)
 757                 sk_filter_uncharge(sk, old_fp);
 758         return 0;
 759 }
 760 EXPORT_SYMBOL_GPL(sk_attach_filter);
 761
 762 int sk_detach_filter(struct sock *sk)
 763 {
 764         int ret = -ENOENT;
 765         struct sk_filter *filter;
 766
 767         if (sock_flag(sk, SOCK_FILTER_LOCKED))
 768                 return -EPERM;
 769
 770         filter = rcu_dereference_protected(sk->sk_filter,
 771                                            sock_owned_by_user(sk));
 772         if (filter) {
 773                 RCU_INIT_POINTER(sk->sk_filter, NULL);
 774                 sk_filter_uncharge(sk, filter);
 775                 ret = 0;
 776         }
 777         return ret;
 778 }
 779 EXPORT_SYMBOL_GPL(sk_detach_filter);
 780
 781 void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to)
 782 {
 783         static const u16 decodes[] = {
 784                 [BPF_S_ALU_ADD_K]       = BPF_ALU|BPF_ADD|BPF_K,
 785                 [BPF_S_ALU_ADD_X]       = BPF_ALU|BPF_ADD|BPF_X,
 786                 [BPF_S_ALU_SUB_K]       = BPF_ALU|BPF_SUB|BPF_K,
 787                 [BPF_S_ALU_SUB_X]       = BPF_ALU|BPF_SUB|BPF_X,
 788                 [BPF_S_ALU_MUL_K]       = BPF_ALU|BPF_MUL|BPF_K,
 789                 [BPF_S_ALU_MUL_X]       = BPF_ALU|BPF_MUL|BPF_X,
 790                 [BPF_S_ALU_DIV_X]       = BPF_ALU|BPF_DIV|BPF_X,
 791                 [BPF_S_ALU_MOD_K]       = BPF_ALU|BPF_MOD|BPF_K,
 792                 [BPF_S_ALU_MOD_X]       = BPF_ALU|BPF_MOD|BPF_X,
 793                 [BPF_S_ALU_AND_K]       = BPF_ALU|BPF_AND|BPF_K,
 794                 [BPF_S_ALU_AND_X]       = BPF_ALU|BPF_AND|BPF_X,
 795                 [BPF_S_ALU_OR_K]        = BPF_ALU|BPF_OR|BPF_K,
 796                 [BPF_S_ALU_OR_X]        = BPF_ALU|BPF_OR|BPF_X,
 797                 [BPF_S_ALU_XOR_K]       = BPF_ALU|BPF_XOR|BPF_K,
 798                 [BPF_S_ALU_XOR_X]       = BPF_ALU|BPF_XOR|BPF_X,
 799                 [BPF_S_ALU_LSH_K]       = BPF_ALU|BPF_LSH|BPF_K,
 800                 [BPF_S_ALU_LSH_X]       = BPF_ALU|BPF_LSH|BPF_X,
 801                 [BPF_S_ALU_RSH_K]       = BPF_ALU|BPF_RSH|BPF_K,
 802                 [BPF_S_ALU_RSH_X]       = BPF_ALU|BPF_RSH|BPF_X,
 803                 [BPF_S_ALU_NEG]         = BPF_ALU|BPF_NEG,
 804                 [BPF_S_LD_W_ABS]        = BPF_LD|BPF_W|BPF_ABS,
 805                 [BPF_S_LD_H_ABS]        = BPF_LD|BPF_H|BPF_ABS,
 806                 [BPF_S_LD_B_ABS]        = BPF_LD|BPF_B|BPF_ABS,
 807                 [BPF_S_ANC_PROTOCOL]    = BPF_LD|BPF_B|BPF_ABS,
 808                 [BPF_S_ANC_PKTTYPE]     = BPF_LD|BPF_B|BPF_ABS,
 809                 [BPF_S_ANC_IFINDEX]     = BPF_LD|BPF_B|BPF_ABS,
 810                 [BPF_S_ANC_NLATTR]      = BPF_LD|BPF_B|BPF_ABS,
 811                 [BPF_S_ANC_NLATTR_NEST] = BPF_LD|BPF_B|BPF_ABS,
 812                 [BPF_S_ANC_MARK]        = BPF_LD|BPF_B|BPF_ABS,
 813                 [BPF_S_ANC_QUEUE]       = BPF_LD|BPF_B|BPF_ABS,
 814                 [BPF_S_ANC_HATYPE]      = BPF_LD|BPF_B|BPF_ABS,
 815                 [BPF_S_ANC_RXHASH]      = BPF_LD|BPF_B|BPF_ABS,
 816                 [BPF_S_ANC_CPU]         = BPF_LD|BPF_B|BPF_ABS,
 817                 [BPF_S_ANC_ALU_XOR_X]   = BPF_LD|BPF_B|BPF_ABS,
 818                 [BPF_S_ANC_SECCOMP_LD_W] = BPF_LD|BPF_B|BPF_ABS,
 819                 [BPF_S_ANC_VLAN_TAG]    = BPF_LD|BPF_B|BPF_ABS,
 820                 [BPF_S_ANC_VLAN_TAG_PRESENT] = BPF_LD|BPF_B|BPF_ABS,
 821                 [BPF_S_ANC_PAY_OFFSET]  = BPF_LD|BPF_B|BPF_ABS,
 822                 [BPF_S_LD_W_LEN]        = BPF_LD|BPF_W|BPF_LEN,
 823                 [BPF_S_LD_W_IND]        = BPF_LD|BPF_W|BPF_IND,
 824                 [BPF_S_LD_H_IND]        = BPF_LD|BPF_H|BPF_IND,
 825                 [BPF_S_LD_B_IND]        = BPF_LD|BPF_B|BPF_IND,
 826                 [BPF_S_LD_IMM]          = BPF_LD|BPF_IMM,
 827                 [BPF_S_LDX_W_LEN]       = BPF_LDX|BPF_W|BPF_LEN,
 828                 [BPF_S_LDX_B_MSH]       = BPF_LDX|BPF_B|BPF_MSH,
 829                 [BPF_S_LDX_IMM]         = BPF_LDX|BPF_IMM,
 830                 [BPF_S_MISC_TAX]        = BPF_MISC|BPF_TAX,
 831                 [BPF_S_MISC_TXA]        = BPF_MISC|BPF_TXA,
 832                 [BPF_S_RET_K]           = BPF_RET|BPF_K,
 833                 [BPF_S_RET_A]           = BPF_RET|BPF_A,
 834                 [BPF_S_ALU_DIV_K]       = BPF_ALU|BPF_DIV|BPF_K,
 835                 [BPF_S_LD_MEM]          = BPF_LD|BPF_MEM,
 836                 [BPF_S_LDX_MEM]         = BPF_LDX|BPF_MEM,
 837                 [BPF_S_ST]              = BPF_ST,
 838                 [BPF_S_STX]             = BPF_STX,
 839                 [BPF_S_JMP_JA]          = BPF_JMP|BPF_JA,
 840                 [BPF_S_JMP_JEQ_K]       = BPF_JMP|BPF_JEQ|BPF_K,
 841                 [BPF_S_JMP_JEQ_X]       = BPF_JMP|BPF_JEQ|BPF_X,
 842                 [BPF_S_JMP_JGE_K]       = BPF_JMP|BPF_JGE|BPF_K,
 843                 [BPF_S_JMP_JGE_X]       = BPF_JMP|BPF_JGE|BPF_X,
 844                 [BPF_S_JMP_JGT_K]       = BPF_JMP|BPF_JGT|BPF_K,
 845                 [BPF_S_JMP_JGT_X]       = BPF_JMP|BPF_JGT|BPF_X,
 846                 [BPF_S_JMP_JSET_K]      = BPF_JMP|BPF_JSET|BPF_K,
 847                 [BPF_S_JMP_JSET_X]      = BPF_JMP|BPF_JSET|BPF_X,
 848         };
 849         u16 code;
 850
 851         code = filt->code;
 852
 853         to->code = decodes[code];
 854         to->jt = filt->jt;
 855         to->jf = filt->jf;
 856
 857         if (code == BPF_S_ALU_DIV_K) {
 858                 /*
 859                  * When loaded this rule user gave us X, which was
 860                  * translated into R = r(X). Now we calculate the
 861                  * RR = r(R) and report it back. If next time this
 862                  * value is loaded and RRR = r(RR) is calculated
 863                  * then the R == RRR will be true.
 864                  *
 865                  * One exception. X == 1 translates into R == 0 and
 866                  * we can't calculate RR out of it with r().
 867                  */
 868
 869                 if (filt->k == 0)
 870                         to->k = 1;
 871                 else
 872                         to->k = reciprocal_value(filt->k);
 873
 874                 BUG_ON(reciprocal_value(to->k) != filt->k);
 875         } else
 876                 to->k = filt->k;
 877 }
 878
 879 int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, unsigned int len)
 880 {
 881         struct sk_filter *filter;
 882         int i, ret;
 883
 884         lock_sock(sk);
 885         filter = rcu_dereference_protected(sk->sk_filter,
 886                         sock_owned_by_user(sk));
 887         ret = 0;
 888         if (!filter)
 889                 goto out;
 890         ret = filter->len;
 891         if (!len)
 892                 goto out;
 893         ret = -EINVAL;
 894         if (len < filter->len)
 895                 goto out;
 896
 897         ret = -EFAULT;
 898         for (i = 0; i < filter->len; i++) {
 899                 struct sock_filter fb;
 900
 901                 sk_decode_filter(&filter->insns[i], &fb);
 902                 if (copy_to_user(&ubuf[i], &fb, sizeof(fb)))
 903                         goto out;
 904         }
 905
 906         ret = filter->len;
 907 out:
 908         release_sock(sk);
 909         return ret;
 910 }