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 #include <asm/cacheflush.h>
  13
  14 struct sk_buff;
  15 struct sock;
  16 struct seccomp_data;
  17
  18 /* Internally used and optimized filter representation with extended
  19  * instruction set based on top of classic BPF.
  20  */
  21
  22 /* instruction classes */
  23 #define BPF_ALU64       0x07    /* alu mode in double word width */
  24
  25 /* ld/ldx fields */
  26 #define BPF_DW          0x18    /* double word */
  27 #define BPF_XADD        0xc0    /* exclusive add */
  28
  29 /* alu/jmp fields */
  30 #define BPF_MOV         0xb0    /* mov reg to reg */
  31 #define BPF_ARSH        0xc0    /* sign extending arithmetic shift right */
  32
  33 /* change endianness of a register */
  34 #define BPF_END         0xd0    /* flags for endianness conversion: */
  35 #define BPF_TO_LE       0x00    /* convert to little-endian */
  36 #define BPF_TO_BE       0x08    /* convert to big-endian */
  37 #define BPF_FROM_LE     BPF_TO_LE
  38 #define BPF_FROM_BE     BPF_TO_BE
  39
  40 #define BPF_JNE         0x50    /* jump != */
  41 #define BPF_JSGT        0x60    /* SGT is signed '>', GT in x86 */
  42 #define BPF_JSGE        0x70    /* SGE is signed '>=', GE in x86 */
  43 #define BPF_CALL        0x80    /* function call */
  44 #define BPF_EXIT        0x90    /* function return */
  45
  46 /* Register numbers */
  47 enum {
  48         BPF_REG_0 = 0,
  49         BPF_REG_1,
  50         BPF_REG_2,
  51         BPF_REG_3,
  52         BPF_REG_4,
  53         BPF_REG_5,
  54         BPF_REG_6,
  55         BPF_REG_7,
  56         BPF_REG_8,
  57         BPF_REG_9,
  58         BPF_REG_10,
  59         __MAX_BPF_REG,
  60 };
  61
  62 /* BPF has 10 general purpose 64-bit registers and stack frame. */
  63 #define MAX_BPF_REG     __MAX_BPF_REG
  64
  65 /* ArgX, context and stack frame pointer register positions. Note,
  66  * Arg1, Arg2, Arg3, etc are used as argument mappings of function
  67  * calls in BPF_CALL instruction.
  68  */
  69 #define BPF_REG_ARG1    BPF_REG_1
  70 #define BPF_REG_ARG2    BPF_REG_2
  71 #define BPF_REG_ARG3    BPF_REG_3
  72 #define BPF_REG_ARG4    BPF_REG_4
  73 #define BPF_REG_ARG5    BPF_REG_5
  74 #define BPF_REG_CTX     BPF_REG_6
  75 #define BPF_REG_FP      BPF_REG_10
  76
  77 /* Additional register mappings for converted user programs. */
  78 #define BPF_REG_A       BPF_REG_0
  79 #define BPF_REG_X       BPF_REG_7
  80 #define BPF_REG_TMP     BPF_REG_8
  81
  82 /* BPF program can access up to 512 bytes of stack space. */
  83 #define MAX_BPF_STACK   512
  84
  85 /* Helper macros for filter block array initializers. */
  86
  87 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
  88
  89 #define BPF_ALU64_REG(OP, DST, SRC)                             \
  90         ((struct bpf_insn) {                                    \
  91                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_X,        \
  92                 .dst_reg = DST,                                 \
  93                 .src_reg = SRC,                                 \
  94                 .off   = 0,                                     \
  95                 .imm   = 0 })
  96
  97 #define BPF_ALU32_REG(OP, DST, SRC)                             \
  98         ((struct bpf_insn) {                                    \
  99                 .code  = BPF_ALU | BPF_OP(OP) | BPF_X,          \
 100                 .dst_reg = DST,                                 \
 101                 .src_reg = SRC,                                 \
 102                 .off   = 0,                                     \
 103                 .imm   = 0 })
 104
 105 /* ALU ops on immediates, bpf_add|sub|...: dst_reg += imm32 */
 106
 107 #define BPF_ALU64_IMM(OP, DST, IMM)                             \
 108         ((struct bpf_insn) {                                    \
 109                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_K,        \
 110                 .dst_reg = DST,                                 \
 111                 .src_reg = 0,                                   \
 112                 .off   = 0,                                     \
 113                 .imm   = IMM })
 114
 115 #define BPF_ALU32_IMM(OP, DST, IMM)                             \
 116         ((struct bpf_insn) {                                    \
 117                 .code  = BPF_ALU | BPF_OP(OP) | BPF_K,          \
 118                 .dst_reg = DST,                                 \
 119                 .src_reg = 0,                                   \
 120                 .off   = 0,                                     \
 121                 .imm   = IMM })
 122
 123 /* Endianess conversion, cpu_to_{l,b}e(), {l,b}e_to_cpu() */
 124
 125 #define BPF_ENDIAN(TYPE, DST, LEN)                              \
 126         ((struct bpf_insn) {                                    \
 127                 .code  = BPF_ALU | BPF_END | BPF_SRC(TYPE),     \
 128                 .dst_reg = DST,                                 \
 129                 .src_reg = 0,                                   \
 130                 .off   = 0,                                     \
 131                 .imm   = LEN })
 132
 133 /* Short form of mov, dst_reg = src_reg */
 134
 135 #define BPF_MOV64_REG(DST, SRC)                                 \
 136         ((struct bpf_insn) {                                    \
 137                 .code  = BPF_ALU64 | BPF_MOV | BPF_X,           \
 138                 .dst_reg = DST,                                 \
 139                 .src_reg = SRC,                                 \
 140                 .off   = 0,                                     \
 141                 .imm   = 0 })
 142
 143 #define BPF_MOV32_REG(DST, SRC)                                 \
 144         ((struct bpf_insn) {                                    \
 145                 .code  = BPF_ALU | BPF_MOV | BPF_X,             \
 146                 .dst_reg = DST,                                 \
 147                 .src_reg = SRC,                                 \
 148                 .off   = 0,                                     \
 149                 .imm   = 0 })
 150
 151 /* Short form of mov, dst_reg = imm32 */
 152
 153 #define BPF_MOV64_IMM(DST, IMM)                                 \
 154         ((struct bpf_insn) {                                    \
 155                 .code  = BPF_ALU64 | BPF_MOV | BPF_K,           \
 156                 .dst_reg = DST,                                 \
 157                 .src_reg = 0,                                   \
 158                 .off   = 0,                                     \
 159                 .imm   = IMM })
 160
 161 #define BPF_MOV32_IMM(DST, IMM)                                 \
 162         ((struct bpf_insn) {                                    \
 163                 .code  = BPF_ALU | BPF_MOV | BPF_K,             \
 164                 .dst_reg = DST,                                 \
 165                 .src_reg = 0,                                   \
 166                 .off   = 0,                                     \
 167                 .imm   = IMM })
 168
 169 /* Short form of mov based on type, BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */
 170
 171 #define BPF_MOV64_RAW(TYPE, DST, SRC, IMM)                      \
 172         ((struct bpf_insn) {                                    \
 173                 .code  = BPF_ALU64 | BPF_MOV | BPF_SRC(TYPE),   \
 174                 .dst_reg = DST,                                 \
 175                 .src_reg = SRC,                                 \
 176                 .off   = 0,                                     \
 177                 .imm   = IMM })
 178
 179 #define BPF_MOV32_RAW(TYPE, DST, SRC, IMM)                      \
 180         ((struct bpf_insn) {                                    \
 181                 .code  = BPF_ALU | BPF_MOV | BPF_SRC(TYPE),     \
 182                 .dst_reg = DST,                                 \
 183                 .src_reg = SRC,                                 \
 184                 .off   = 0,                                     \
 185                 .imm   = IMM })
 186
 187 /* Direct packet access, R0 = *(uint *) (skb->data + imm32) */
 188
 189 #define BPF_LD_ABS(SIZE, IMM)                                   \
 190         ((struct bpf_insn) {                                    \
 191                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_ABS,     \
 192                 .dst_reg = 0,                                   \
 193                 .src_reg = 0,                                   \
 194                 .off   = 0,                                     \
 195                 .imm   = IMM })
 196
 197 /* Indirect packet access, R0 = *(uint *) (skb->data + src_reg + imm32) */
 198
 199 #define BPF_LD_IND(SIZE, SRC, IMM)                              \
 200         ((struct bpf_insn) {                                    \
 201                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_IND,     \
 202                 .dst_reg = 0,                                   \
 203                 .src_reg = SRC,                                 \
 204                 .off   = 0,                                     \
 205                 .imm   = IMM })
 206
 207 /* Memory load, dst_reg = *(uint *) (src_reg + off16) */
 208
 209 #define BPF_LDX_MEM(SIZE, DST, SRC, OFF)                        \
 210         ((struct bpf_insn) {                                    \
 211                 .code  = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM,    \
 212                 .dst_reg = DST,                                 \
 213                 .src_reg = SRC,                                 \
 214                 .off   = OFF,                                   \
 215                 .imm   = 0 })
 216
 217 /* Memory store, *(uint *) (dst_reg + off16) = src_reg */
 218
 219 #define BPF_STX_MEM(SIZE, DST, SRC, OFF)                        \
 220         ((struct bpf_insn) {                                    \
 221                 .code  = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM,    \
 222                 .dst_reg = DST,                                 \
 223                 .src_reg = SRC,                                 \
 224                 .off   = OFF,                                   \
 225                 .imm   = 0 })
 226
 227 /* Memory store, *(uint *) (dst_reg + off16) = imm32 */
 228
 229 #define BPF_ST_MEM(SIZE, DST, OFF, IMM)                         \
 230         ((struct bpf_insn) {                                    \
 231                 .code  = BPF_ST | BPF_SIZE(SIZE) | BPF_MEM,     \
 232                 .dst_reg = DST,                                 \
 233                 .src_reg = 0,                                   \
 234                 .off   = OFF,                                   \
 235                 .imm   = IMM })
 236
 237 /* Conditional jumps against registers, if (dst_reg 'op' src_reg) goto pc + off16 */
 238
 239 #define BPF_JMP_REG(OP, DST, SRC, OFF)                          \
 240         ((struct bpf_insn) {                                    \
 241                 .code  = BPF_JMP | BPF_OP(OP) | BPF_X,          \
 242                 .dst_reg = DST,                                 \
 243                 .src_reg = SRC,                                 \
 244                 .off   = OFF,                                   \
 245                 .imm   = 0 })
 246
 247 /* Conditional jumps against immediates, if (dst_reg 'op' imm32) goto pc + off16 */
 248
 249 #define BPF_JMP_IMM(OP, DST, IMM, OFF)                          \
 250         ((struct bpf_insn) {                                    \
 251                 .code  = BPF_JMP | BPF_OP(OP) | BPF_K,          \
 252                 .dst_reg = DST,                                 \
 253                 .src_reg = 0,                                   \
 254                 .off   = OFF,                                   \
 255                 .imm   = IMM })
 256
 257 /* Function call */
 258
 259 #define BPF_EMIT_CALL(FUNC)                                     \
 260         ((struct bpf_insn) {                                    \
 261                 .code  = BPF_JMP | BPF_CALL,                    \
 262                 .dst_reg = 0,                                   \
 263                 .src_reg = 0,                                   \
 264                 .off   = 0,                                     \
 265                 .imm   = ((FUNC) - __bpf_call_base) })
 266
 267 /* Raw code statement block */
 268
 269 #define BPF_RAW_INSN(CODE, DST, SRC, OFF, IMM)                  \
 270         ((struct bpf_insn) {                                    \
 271                 .code  = CODE,                                  \
 272                 .dst_reg = DST,                                 \
 273                 .src_reg = SRC,                                 \
 274                 .off   = OFF,                                   \
 275                 .imm   = IMM })
 276
 277 /* Program exit */
 278
 279 #define BPF_EXIT_INSN()                                         \
 280         ((struct bpf_insn) {                                    \
 281                 .code  = BPF_JMP | BPF_EXIT,                    \
 282                 .dst_reg = 0,                                   \
 283                 .src_reg = 0,                                   \
 284                 .off   = 0,                                     \
 285                 .imm   = 0 })
 286
 287 #define bytes_to_bpf_size(bytes)                                \
 288 ({                                                              \
 289         int bpf_size = -EINVAL;                                 \
 290                                                                 \
 291         if (bytes == sizeof(u8))                                \
 292                 bpf_size = BPF_B;                               \
 293         else if (bytes == sizeof(u16))                          \
 294                 bpf_size = BPF_H;                               \
 295         else if (bytes == sizeof(u32))                          \
 296                 bpf_size = BPF_W;                               \
 297         else if (bytes == sizeof(u64))                          \
 298                 bpf_size = BPF_DW;                              \
 299                                                                 \
 300         bpf_size;                                               \
 301 })
 302
 303 /* Macro to invoke filter function. */
 304 #define SK_RUN_FILTER(filter, ctx) \
 305         (*filter->prog->bpf_func)(ctx, filter->prog->insnsi)
 306
 307 struct bpf_insn {
 308         __u8    code;           /* opcode */
 309         __u8    dst_reg:4;      /* dest register */
 310         __u8    src_reg:4;      /* source register */
 311         __s16   off;            /* signed offset */
 312         __s32   imm;            /* signed immediate constant */
 313 };
 314
 315 #ifdef CONFIG_COMPAT
 316 /* A struct sock_filter is architecture independent. */
 317 struct compat_sock_fprog {
 318         u16             len;
 319         compat_uptr_t   filter; /* struct sock_filter * */
 320 };
 321 #endif
 322
 323 struct sock_fprog_kern {
 324         u16                     len;
 325         struct sock_filter      *filter;
 326 };
 327
 328 struct bpf_work_struct {
 329         struct bpf_prog *prog;
 330         struct work_struct work;
 331 };
 332
 333 struct bpf_prog {
 334         u32                     pages;          /* Number of allocated pages */
 335         u32                     jited:1,        /* Is our filter JIT'ed? */
 336                                 len:31;         /* Number of filter blocks */
 337         struct sock_fprog_kern  *orig_prog;     /* Original BPF program */
 338         struct bpf_work_struct  *work;          /* Deferred free work struct */
 339         unsigned int            (*bpf_func)(const struct sk_buff *skb,
 340                                             const struct bpf_insn *filter);
 341         /* Instructions for interpreter */
 342         union {
 343                 struct sock_filter      insns[0];
 344                 struct bpf_insn         insnsi[0];
 345         };
 346 };
 347
 348 struct sk_filter {
 349         atomic_t        refcnt;
 350         struct rcu_head rcu;
 351         struct bpf_prog *prog;
 352 };
 353
 354 #define BPF_PROG_RUN(filter, ctx)  (*filter->bpf_func)(ctx, filter->insnsi)
 355
 356 static inline unsigned int bpf_prog_size(unsigned int proglen)
 357 {
 358         return max(sizeof(struct bpf_prog),
 359                    offsetof(struct bpf_prog, insns[proglen]));
 360 }
 361
 362 #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
 363
 364 #ifdef CONFIG_DEBUG_SET_MODULE_RONX
 365 static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 366 {
 367         set_memory_ro((unsigned long)fp, fp->pages);
 368 }
 369
 370 static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
 371 {
 372         set_memory_rw((unsigned long)fp, fp->pages);
 373 }
 374 #else
 375 static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 376 {
 377 }
 378
 379 static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
 380 {
 381 }
 382 #endif /* CONFIG_DEBUG_SET_MODULE_RONX */
 383
 384 int sk_filter(struct sock *sk, struct sk_buff *skb);
 385
 386 void bpf_prog_select_runtime(struct bpf_prog *fp);
 387 void bpf_prog_free(struct bpf_prog *fp);
 388
 389 int bpf_convert_filter(struct sock_filter *prog, int len,
 390                        struct bpf_insn *new_prog, int *new_len);
 391
 392 struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags);
 393 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 394                                   gfp_t gfp_extra_flags);
 395 void __bpf_prog_free(struct bpf_prog *fp);
 396
 397 static inline void bpf_prog_unlock_free(struct bpf_prog *fp)
 398 {
 399         bpf_prog_unlock_ro(fp);
 400         __bpf_prog_free(fp);
 401 }
 402
 403 int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog);
 404 void bpf_prog_destroy(struct bpf_prog *fp);
 405
 406 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 407 int sk_detach_filter(struct sock *sk);
 408
 409 int bpf_check_classic(const struct sock_filter *filter, unsigned int flen);
 410 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 411                   unsigned int len);
 412
 413 bool sk_filter_charge(struct sock *sk, struct sk_filter *fp);
 414 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 415
 416 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 417 void bpf_int_jit_compile(struct bpf_prog *fp);
 418
 419 #define BPF_ANC         BIT(15)
 420
 421 static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
 422 {
 423         BUG_ON(ftest->code & BPF_ANC);
 424
 425         switch (ftest->code) {
 426         case BPF_LD | BPF_W | BPF_ABS:
 427         case BPF_LD | BPF_H | BPF_ABS:
 428         case BPF_LD | BPF_B | BPF_ABS:
 429 #define BPF_ANCILLARY(CODE)     case SKF_AD_OFF + SKF_AD_##CODE:        \
 430                                 return BPF_ANC | SKF_AD_##CODE
 431                 switch (ftest->k) {
 432                 BPF_ANCILLARY(PROTOCOL);
 433                 BPF_ANCILLARY(PKTTYPE);
 434                 BPF_ANCILLARY(IFINDEX);
 435                 BPF_ANCILLARY(NLATTR);
 436                 BPF_ANCILLARY(NLATTR_NEST);
 437                 BPF_ANCILLARY(MARK);
 438                 BPF_ANCILLARY(QUEUE);
 439                 BPF_ANCILLARY(HATYPE);
 440                 BPF_ANCILLARY(RXHASH);
 441                 BPF_ANCILLARY(CPU);
 442                 BPF_ANCILLARY(ALU_XOR_X);
 443                 BPF_ANCILLARY(VLAN_TAG);
 444                 BPF_ANCILLARY(VLAN_TAG_PRESENT);
 445                 BPF_ANCILLARY(PAY_OFFSET);
 446                 BPF_ANCILLARY(RANDOM);
 447                 }
 448                 /* Fallthrough. */
 449         default:
 450                 return ftest->code;
 451         }
 452 }
 453
 454 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb,
 455                                            int k, unsigned int size);
 456
 457 static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
 458                                      unsigned int size, void *buffer)
 459 {
 460         if (k >= 0)
 461                 return skb_header_pointer(skb, k, size, buffer);
 462
 463         return bpf_internal_load_pointer_neg_helper(skb, k, size);
 464 }
 465
 466 #ifdef CONFIG_BPF_JIT
 467 #include <stdarg.h>
 468 #include <linux/linkage.h>
 469 #include <linux/printk.h>
 470
 471 void bpf_jit_compile(struct bpf_prog *fp);
 472 void bpf_jit_free(struct bpf_prog *fp);
 473
 474 static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
 475                                 u32 pass, void *image)
 476 {
 477         pr_err("flen=%u proglen=%u pass=%u image=%pK\n",
 478                flen, proglen, pass, image);
 479         if (image)
 480                 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET,
 481                                16, 1, image, proglen, false);
 482 }
 483 #else
 484 #include <linux/slab.h>
 485
 486 static inline void bpf_jit_compile(struct bpf_prog *fp)
 487 {
 488 }
 489
 490 static inline void bpf_jit_free(struct bpf_prog *fp)
 491 {
 492         bpf_prog_unlock_free(fp);
 493 }
 494 #endif /* CONFIG_BPF_JIT */
 495
 496 static inline int bpf_tell_extensions(void)
 497 {
 498         return SKF_AD_MAX;
 499 }
 500
 501 #endif /* __LINUX_FILTER_H__ */