include/linux/filter.h

   1 /*
   2  * Linux Socket Filter Data Structures
   3  */
   4 #ifndef __LINUX_FILTER_H__
   5 #define __LINUX_FILTER_H__
   6
   7 #include <linux/atomic.h>
   8 #include <linux/compat.h>
   9 #include <linux/skbuff.h>
  10 #include <linux/workqueue.h>
  11 #include <uapi/linux/filter.h>
  12
  13 /* Internally used and optimized filter representation with extended
  14  * instruction set based on top of classic BPF.
  15  */
  16
  17 /* instruction classes */
  18 #define BPF_ALU64       0x07    /* alu mode in double word width */
  19
  20 /* ld/ldx fields */
  21 #define BPF_DW          0x18    /* double word */
  22 #define BPF_XADD        0xc0    /* exclusive add */
  23
  24 /* alu/jmp fields */
  25 #define BPF_MOV         0xb0    /* mov reg to reg */
  26 #define BPF_ARSH        0xc0    /* sign extending arithmetic shift right */
  27
  28 /* change endianness of a register */
  29 #define BPF_END         0xd0    /* flags for endianness conversion: */
  30 #define BPF_TO_LE       0x00    /* convert to little-endian */
  31 #define BPF_TO_BE       0x08    /* convert to big-endian */
  32 #define BPF_FROM_LE     BPF_TO_LE
  33 #define BPF_FROM_BE     BPF_TO_BE
  34
  35 #define BPF_JNE         0x50    /* jump != */
  36 #define BPF_JSGT        0x60    /* SGT is signed '>', GT in x86 */
  37 #define BPF_JSGE        0x70    /* SGE is signed '>=', GE in x86 */
  38 #define BPF_CALL        0x80    /* function call */
  39 #define BPF_EXIT        0x90    /* function return */
  40
  41 /* Register numbers */
  42 enum {
  43         BPF_REG_0 = 0,
  44         BPF_REG_1,
  45         BPF_REG_2,
  46         BPF_REG_3,
  47         BPF_REG_4,
  48         BPF_REG_5,
  49         BPF_REG_6,
  50         BPF_REG_7,
  51         BPF_REG_8,
  52         BPF_REG_9,
  53         BPF_REG_10,
  54         __MAX_BPF_REG,
  55 };
  56
  57 /* BPF has 10 general purpose 64-bit registers and stack frame. */
  58 #define MAX_BPF_REG     __MAX_BPF_REG
  59
  60 /* ArgX, context and stack frame pointer register positions. Note,
  61  * Arg1, Arg2, Arg3, etc are used as argument mappings of function
  62  * calls in BPF_CALL instruction.
  63  */
  64 #define BPF_REG_ARG1    BPF_REG_1
  65 #define BPF_REG_ARG2    BPF_REG_2
  66 #define BPF_REG_ARG3    BPF_REG_3
  67 #define BPF_REG_ARG4    BPF_REG_4
  68 #define BPF_REG_ARG5    BPF_REG_5
  69 #define BPF_REG_CTX     BPF_REG_6
  70 #define BPF_REG_FP      BPF_REG_10
  71
  72 /* Additional register mappings for converted user programs. */
  73 #define BPF_REG_A       BPF_REG_0
  74 #define BPF_REG_X       BPF_REG_7
  75 #define BPF_REG_TMP     BPF_REG_8
  76
  77 /* BPF program can access up to 512 bytes of stack space. */
  78 #define MAX_BPF_STACK   512
  79
  80 /* Helper macros for filter block array initializers. */
  81
  82 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
  83
  84 #define BPF_ALU64_REG(OP, DST, SRC)                             \
  85         ((struct bpf_insn) {                                    \
  86                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_X,        \
  87                 .dst_reg = DST,                                 \
  88                 .src_reg = SRC,                                 \
  89                 .off   = 0,                                     \
  90                 .imm   = 0 })
  91
  92 #define BPF_ALU32_REG(OP, DST, SRC)                             \
  93         ((struct bpf_insn) {                                    \
  94                 .code  = BPF_ALU | BPF_OP(OP) | BPF_X,          \
  95                 .dst_reg = DST,                                 \
  96                 .src_reg = SRC,                                 \
  97                 .off   = 0,                                     \
  98                 .imm   = 0 })
  99
 100 /* ALU ops on immediates, bpf_add|sub|...: dst_reg += imm32 */
 101
 102 #define BPF_ALU64_IMM(OP, DST, IMM)                             \
 103         ((struct bpf_insn) {                                    \
 104                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_K,        \
 105                 .dst_reg = DST,                                 \
 106                 .src_reg = 0,                                   \
 107                 .off   = 0,                                     \
 108                 .imm   = IMM })
 109
 110 #define BPF_ALU32_IMM(OP, DST, IMM)                             \
 111         ((struct bpf_insn) {                                    \
 112                 .code  = BPF_ALU | BPF_OP(OP) | BPF_K,          \
 113                 .dst_reg = DST,                                 \
 114                 .src_reg = 0,                                   \
 115                 .off   = 0,                                     \
 116                 .imm   = IMM })
 117
 118 /* Endianess conversion, cpu_to_{l,b}e(), {l,b}e_to_cpu() */
 119
 120 #define BPF_ENDIAN(TYPE, DST, LEN)                              \
 121         ((struct bpf_insn) {                                    \
 122                 .code  = BPF_ALU | BPF_END | BPF_SRC(TYPE),     \
 123                 .dst_reg = DST,                                 \
 124                 .src_reg = 0,                                   \
 125                 .off   = 0,                                     \
 126                 .imm   = LEN })
 127
 128 /* Short form of mov, dst_reg = src_reg */
 129
 130 #define BPF_MOV64_REG(DST, SRC)                                 \
 131         ((struct bpf_insn) {                                    \
 132                 .code  = BPF_ALU64 | BPF_MOV | BPF_X,           \
 133                 .dst_reg = DST,                                 \
 134                 .src_reg = SRC,                                 \
 135                 .off   = 0,                                     \
 136                 .imm   = 0 })
 137
 138 #define BPF_MOV32_REG(DST, SRC)                                 \
 139         ((struct bpf_insn) {                                    \
 140                 .code  = BPF_ALU | BPF_MOV | BPF_X,             \
 141                 .dst_reg = DST,                                 \
 142                 .src_reg = SRC,                                 \
 143                 .off   = 0,                                     \
 144                 .imm   = 0 })
 145
 146 /* Short form of mov, dst_reg = imm32 */
 147
 148 #define BPF_MOV64_IMM(DST, IMM)                                 \
 149         ((struct bpf_insn) {                                    \
 150                 .code  = BPF_ALU64 | BPF_MOV | BPF_K,           \
 151                 .dst_reg = DST,                                 \
 152                 .src_reg = 0,                                   \
 153                 .off   = 0,                                     \
 154                 .imm   = IMM })
 155
 156 #define BPF_MOV32_IMM(DST, IMM)                                 \
 157         ((struct bpf_insn) {                                    \
 158                 .code  = BPF_ALU | BPF_MOV | BPF_K,             \
 159                 .dst_reg = DST,                                 \
 160                 .src_reg = 0,                                   \
 161                 .off   = 0,                                     \
 162                 .imm   = IMM })
 163
 164 /* Short form of mov based on type, BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */
 165
 166 #define BPF_MOV64_RAW(TYPE, DST, SRC, IMM)                      \
 167         ((struct bpf_insn) {                                    \
 168                 .code  = BPF_ALU64 | BPF_MOV | BPF_SRC(TYPE),   \
 169                 .dst_reg = DST,                                 \
 170                 .src_reg = SRC,                                 \
 171                 .off   = 0,                                     \
 172                 .imm   = IMM })
 173
 174 #define BPF_MOV32_RAW(TYPE, DST, SRC, IMM)                      \
 175         ((struct bpf_insn) {                                    \
 176                 .code  = BPF_ALU | BPF_MOV | BPF_SRC(TYPE),     \
 177                 .dst_reg = DST,                                 \
 178                 .src_reg = SRC,                                 \
 179                 .off   = 0,                                     \
 180                 .imm   = IMM })
 181
 182 /* Direct packet access, R0 = *(uint *) (skb->data + imm32) */
 183
 184 #define BPF_LD_ABS(SIZE, IMM)                                   \
 185         ((struct bpf_insn) {                                    \
 186                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_ABS,     \
 187                 .dst_reg = 0,                                   \
 188                 .src_reg = 0,                                   \
 189                 .off   = 0,                                     \
 190                 .imm   = IMM })
 191
 192 /* Indirect packet access, R0 = *(uint *) (skb->data + src_reg + imm32) */
 193
 194 #define BPF_LD_IND(SIZE, SRC, IMM)                              \
 195         ((struct bpf_insn) {                                    \
 196                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_IND,     \
 197                 .dst_reg = 0,                                   \
 198                 .src_reg = SRC,                                 \
 199                 .off   = 0,                                     \
 200                 .imm   = IMM })
 201
 202 /* Memory load, dst_reg = *(uint *) (src_reg + off16) */
 203
 204 #define BPF_LDX_MEM(SIZE, DST, SRC, OFF)                        \
 205         ((struct bpf_insn) {                                    \
 206                 .code  = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM,    \
 207                 .dst_reg = DST,                                 \
 208                 .src_reg = SRC,                                 \
 209                 .off   = OFF,                                   \
 210                 .imm   = 0 })
 211
 212 /* Memory store, *(uint *) (dst_reg + off16) = src_reg */
 213
 214 #define BPF_STX_MEM(SIZE, DST, SRC, OFF)                        \
 215         ((struct bpf_insn) {                                    \
 216                 .code  = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM,    \
 217                 .dst_reg = DST,                                 \
 218                 .src_reg = SRC,                                 \
 219                 .off   = OFF,                                   \
 220                 .imm   = 0 })
 221
 222 /* Memory store, *(uint *) (dst_reg + off16) = imm32 */
 223
 224 #define BPF_ST_MEM(SIZE, DST, OFF, IMM)                         \
 225         ((struct bpf_insn) {                                    \
 226                 .code  = BPF_ST | BPF_SIZE(SIZE) | BPF_MEM,     \
 227                 .dst_reg = DST,                                 \
 228                 .src_reg = 0,                                   \
 229                 .off   = OFF,                                   \
 230                 .imm   = IMM })
 231
 232 /* Conditional jumps against registers, if (dst_reg 'op' src_reg) goto pc + off16 */
 233
 234 #define BPF_JMP_REG(OP, DST, SRC, OFF)                          \
 235         ((struct bpf_insn) {                                    \
 236                 .code  = BPF_JMP | BPF_OP(OP) | BPF_X,          \
 237                 .dst_reg = DST,                                 \
 238                 .src_reg = SRC,                                 \
 239                 .off   = OFF,                                   \
 240                 .imm   = 0 })
 241
 242 /* Conditional jumps against immediates, if (dst_reg 'op' imm32) goto pc + off16 */
 243
 244 #define BPF_JMP_IMM(OP, DST, IMM, OFF)                          \
 245         ((struct bpf_insn) {                                    \
 246                 .code  = BPF_JMP | BPF_OP(OP) | BPF_K,          \
 247                 .dst_reg = DST,                                 \
 248                 .src_reg = 0,                                   \
 249                 .off   = OFF,                                   \
 250                 .imm   = IMM })
 251
 252 /* Function call */
 253
 254 #define BPF_EMIT_CALL(FUNC)                                     \
 255         ((struct bpf_insn) {                                    \
 256                 .code  = BPF_JMP | BPF_CALL,                    \
 257                 .dst_reg = 0,                                   \
 258                 .src_reg = 0,                                   \
 259                 .off   = 0,                                     \
 260                 .imm   = ((FUNC) - __bpf_call_base) })
 261
 262 /* Raw code statement block */
 263
 264 #define BPF_RAW_INSN(CODE, DST, SRC, OFF, IMM)                  \
 265         ((struct bpf_insn) {                                    \
 266                 .code  = CODE,                                  \
 267                 .dst_reg = DST,                                 \
 268                 .src_reg = SRC,                                 \
 269                 .off   = OFF,                                   \
 270                 .imm   = IMM })
 271
 272 /* Program exit */
 273
 274 #define BPF_EXIT_INSN()                                         \
 275         ((struct bpf_insn) {                                    \
 276                 .code  = BPF_JMP | BPF_EXIT,                    \
 277                 .dst_reg = 0,                                   \
 278                 .src_reg = 0,                                   \
 279                 .off   = 0,                                     \
 280                 .imm   = 0 })
 281
 282 #define bytes_to_bpf_size(bytes)                                \
 283 ({                                                              \
 284         int bpf_size = -EINVAL;                                 \
 285                                                                 \
 286         if (bytes == sizeof(u8))                                \
 287                 bpf_size = BPF_B;                               \
 288         else if (bytes == sizeof(u16))                          \
 289                 bpf_size = BPF_H;                               \
 290         else if (bytes == sizeof(u32))                          \
 291                 bpf_size = BPF_W;                               \
 292         else if (bytes == sizeof(u64))                          \
 293                 bpf_size = BPF_DW;                              \
 294                                                                 \
 295         bpf_size;                                               \
 296 })
 297
 298 /* Macro to invoke filter function. */
 299 #define SK_RUN_FILTER(filter, ctx) \
 300         (*filter->prog->bpf_func)(ctx, filter->prog->insnsi)
 301
 302 struct bpf_insn {
 303         __u8    code;           /* opcode */
 304         __u8    dst_reg:4;      /* dest register */
 305         __u8    src_reg:4;      /* source register */
 306         __s16   off;            /* signed offset */
 307         __s32   imm;            /* signed immediate constant */
 308 };
 309
 310 #ifdef CONFIG_COMPAT
 311 /* A struct sock_filter is architecture independent. */
 312 struct compat_sock_fprog {
 313         u16             len;
 314         compat_uptr_t   filter; /* struct sock_filter * */
 315 };
 316 #endif
 317
 318 struct sock_fprog_kern {
 319         u16                     len;
 320         struct sock_filter      *filter;
 321 };
 322
 323 struct sk_buff;
 324 struct sock;
 325 struct seccomp_data;
 326
 327 struct bpf_prog {
 328         u32                     jited:1,        /* Is our filter JIT'ed? */
 329                                 len:31;         /* Number of filter blocks */
 330         struct sock_fprog_kern  *orig_prog;     /* Original BPF program */
 331         unsigned int            (*bpf_func)(const struct sk_buff *skb,
 332                                             const struct bpf_insn *filter);
 333         union {
 334                 struct sock_filter      insns[0];
 335                 struct bpf_insn         insnsi[0];
 336                 struct work_struct      work;
 337         };
 338 };
 339
 340 struct sk_filter {
 341         atomic_t        refcnt;
 342         struct rcu_head rcu;
 343         struct bpf_prog *prog;
 344 };
 345
 346 #define BPF_PROG_RUN(filter, ctx)  (*filter->bpf_func)(ctx, filter->insnsi)
 347
 348 static inline unsigned int bpf_prog_size(unsigned int proglen)
 349 {
 350         return max(sizeof(struct bpf_prog),
 351                    offsetof(struct bpf_prog, insns[proglen]));
 352 }
 353
 354 #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
 355
 356 int sk_filter(struct sock *sk, struct sk_buff *skb);
 357
 358 void bpf_prog_select_runtime(struct bpf_prog *fp);
 359 void bpf_prog_free(struct bpf_prog *fp);
 360
 361 int bpf_convert_filter(struct sock_filter *prog, int len,
 362                        struct bpf_insn *new_prog, int *new_len);
 363
 364 int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog);
 365 void bpf_prog_destroy(struct bpf_prog *fp);
 366
 367 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 368 int sk_detach_filter(struct sock *sk);
 369
 370 int bpf_check_classic(const struct sock_filter *filter, unsigned int flen);
 371 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 372                   unsigned int len);
 373
 374 bool sk_filter_charge(struct sock *sk, struct sk_filter *fp);
 375 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 376
 377 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 378 void bpf_int_jit_compile(struct bpf_prog *fp);
 379
 380 #define BPF_ANC         BIT(15)
 381
 382 static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
 383 {
 384         BUG_ON(ftest->code & BPF_ANC);
 385
 386         switch (ftest->code) {
 387         case BPF_LD | BPF_W | BPF_ABS:
 388         case BPF_LD | BPF_H | BPF_ABS:
 389         case BPF_LD | BPF_B | BPF_ABS:
 390 #define BPF_ANCILLARY(CODE)     case SKF_AD_OFF + SKF_AD_##CODE:        \
 391                                 return BPF_ANC | SKF_AD_##CODE
 392                 switch (ftest->k) {
 393                 BPF_ANCILLARY(PROTOCOL);
 394                 BPF_ANCILLARY(PKTTYPE);
 395                 BPF_ANCILLARY(IFINDEX);
 396                 BPF_ANCILLARY(NLATTR);
 397                 BPF_ANCILLARY(NLATTR_NEST);
 398                 BPF_ANCILLARY(MARK);
 399                 BPF_ANCILLARY(QUEUE);
 400                 BPF_ANCILLARY(HATYPE);
 401                 BPF_ANCILLARY(RXHASH);
 402                 BPF_ANCILLARY(CPU);
 403                 BPF_ANCILLARY(ALU_XOR_X);
 404                 BPF_ANCILLARY(VLAN_TAG);
 405                 BPF_ANCILLARY(VLAN_TAG_PRESENT);
 406                 BPF_ANCILLARY(PAY_OFFSET);
 407                 BPF_ANCILLARY(RANDOM);
 408                 }
 409                 /* Fallthrough. */
 410         default:
 411                 return ftest->code;
 412         }
 413 }
 414
 415 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb,
 416                                            int k, unsigned int size);
 417
 418 static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
 419                                      unsigned int size, void *buffer)
 420 {
 421         if (k >= 0)
 422                 return skb_header_pointer(skb, k, size, buffer);
 423
 424         return bpf_internal_load_pointer_neg_helper(skb, k, size);
 425 }
 426
 427 #ifdef CONFIG_BPF_JIT
 428 #include <stdarg.h>
 429 #include <linux/linkage.h>
 430 #include <linux/printk.h>
 431
 432 void bpf_jit_compile(struct bpf_prog *fp);
 433 void bpf_jit_free(struct bpf_prog *fp);
 434
 435 static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
 436                                 u32 pass, void *image)
 437 {
 438         pr_err("flen=%u proglen=%u pass=%u image=%pK\n",
 439                flen, proglen, pass, image);
 440         if (image)
 441                 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET,
 442                                16, 1, image, proglen, false);
 443 }
 444 #else
 445 #include <linux/slab.h>
 446
 447 static inline void bpf_jit_compile(struct bpf_prog *fp)
 448 {
 449 }
 450
 451 static inline void bpf_jit_free(struct bpf_prog *fp)
 452 {
 453         kfree(fp);
 454 }
 455 #endif /* CONFIG_BPF_JIT */
 456
 457 static inline int bpf_tell_extensions(void)
 458 {
 459         return SKF_AD_MAX;
 460 }
 461
 462 #endif /* __LINUX_FILTER_H__ */