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 <stdarg.h>
   8
   9 #include <linux/atomic.h>
  10 #include <linux/compat.h>
  11 #include <linux/skbuff.h>
  12 #include <linux/linkage.h>
  13 #include <linux/printk.h>
  14 #include <linux/workqueue.h>
  15 #include <linux/sched.h>
  16
  17 #include <asm/cacheflush.h>
  18
  19 #include <uapi/linux/filter.h>
  20 #include <uapi/linux/bpf.h>
  21
  22 struct sk_buff;
  23 struct sock;
  24 struct seccomp_data;
  25 struct bpf_prog_aux;
  26
  27 /* ArgX, context and stack frame pointer register positions. Note,
  28  * Arg1, Arg2, Arg3, etc are used as argument mappings of function
  29  * calls in BPF_CALL instruction.
  30  */
  31 #define BPF_REG_ARG1    BPF_REG_1
  32 #define BPF_REG_ARG2    BPF_REG_2
  33 #define BPF_REG_ARG3    BPF_REG_3
  34 #define BPF_REG_ARG4    BPF_REG_4
  35 #define BPF_REG_ARG5    BPF_REG_5
  36 #define BPF_REG_CTX     BPF_REG_6
  37 #define BPF_REG_FP      BPF_REG_10
  38
  39 /* Additional register mappings for converted user programs. */
  40 #define BPF_REG_A       BPF_REG_0
  41 #define BPF_REG_X       BPF_REG_7
  42 #define BPF_REG_TMP     BPF_REG_8
  43
  44 /* BPF program can access up to 512 bytes of stack space. */
  45 #define MAX_BPF_STACK   512
  46
  47 /* Helper macros for filter block array initializers. */
  48
  49 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
  50
  51 #define BPF_ALU64_REG(OP, DST, SRC)                             \
  52         ((struct bpf_insn) {                                    \
  53                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_X,        \
  54                 .dst_reg = DST,                                 \
  55                 .src_reg = SRC,                                 \
  56                 .off   = 0,                                     \
  57                 .imm   = 0 })
  58
  59 #define BPF_ALU32_REG(OP, DST, SRC)                             \
  60         ((struct bpf_insn) {                                    \
  61                 .code  = BPF_ALU | BPF_OP(OP) | BPF_X,          \
  62                 .dst_reg = DST,                                 \
  63                 .src_reg = SRC,                                 \
  64                 .off   = 0,                                     \
  65                 .imm   = 0 })
  66
  67 /* ALU ops on immediates, bpf_add|sub|...: dst_reg += imm32 */
  68
  69 #define BPF_ALU64_IMM(OP, DST, IMM)                             \
  70         ((struct bpf_insn) {                                    \
  71                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_K,        \
  72                 .dst_reg = DST,                                 \
  73                 .src_reg = 0,                                   \
  74                 .off   = 0,                                     \
  75                 .imm   = IMM })
  76
  77 #define BPF_ALU32_IMM(OP, DST, IMM)                             \
  78         ((struct bpf_insn) {                                    \
  79                 .code  = BPF_ALU | BPF_OP(OP) | BPF_K,          \
  80                 .dst_reg = DST,                                 \
  81                 .src_reg = 0,                                   \
  82                 .off   = 0,                                     \
  83                 .imm   = IMM })
  84
  85 /* Endianess conversion, cpu_to_{l,b}e(), {l,b}e_to_cpu() */
  86
  87 #define BPF_ENDIAN(TYPE, DST, LEN)                              \
  88         ((struct bpf_insn) {                                    \
  89                 .code  = BPF_ALU | BPF_END | BPF_SRC(TYPE),     \
  90                 .dst_reg = DST,                                 \
  91                 .src_reg = 0,                                   \
  92                 .off   = 0,                                     \
  93                 .imm   = LEN })
  94
  95 /* Short form of mov, dst_reg = src_reg */
  96
  97 #define BPF_MOV64_REG(DST, SRC)                                 \
  98         ((struct bpf_insn) {                                    \
  99                 .code  = BPF_ALU64 | BPF_MOV | BPF_X,           \
 100                 .dst_reg = DST,                                 \
 101                 .src_reg = SRC,                                 \
 102                 .off   = 0,                                     \
 103                 .imm   = 0 })
 104
 105 #define BPF_MOV32_REG(DST, SRC)                                 \
 106         ((struct bpf_insn) {                                    \
 107                 .code  = BPF_ALU | BPF_MOV | BPF_X,             \
 108                 .dst_reg = DST,                                 \
 109                 .src_reg = SRC,                                 \
 110                 .off   = 0,                                     \
 111                 .imm   = 0 })
 112
 113 /* Short form of mov, dst_reg = imm32 */
 114
 115 #define BPF_MOV64_IMM(DST, IMM)                                 \
 116         ((struct bpf_insn) {                                    \
 117                 .code  = BPF_ALU64 | BPF_MOV | BPF_K,           \
 118                 .dst_reg = DST,                                 \
 119                 .src_reg = 0,                                   \
 120                 .off   = 0,                                     \
 121                 .imm   = IMM })
 122
 123 #define BPF_MOV32_IMM(DST, IMM)                                 \
 124         ((struct bpf_insn) {                                    \
 125                 .code  = BPF_ALU | BPF_MOV | BPF_K,             \
 126                 .dst_reg = DST,                                 \
 127                 .src_reg = 0,                                   \
 128                 .off   = 0,                                     \
 129                 .imm   = IMM })
 130
 131 /* BPF_LD_IMM64 macro encodes single 'load 64-bit immediate' insn */
 132 #define BPF_LD_IMM64(DST, IMM)                                  \
 133         BPF_LD_IMM64_RAW(DST, 0, IMM)
 134
 135 #define BPF_LD_IMM64_RAW(DST, SRC, IMM)                         \
 136         ((struct bpf_insn) {                                    \
 137                 .code  = BPF_LD | BPF_DW | BPF_IMM,             \
 138                 .dst_reg = DST,                                 \
 139                 .src_reg = SRC,                                 \
 140                 .off   = 0,                                     \
 141                 .imm   = (__u32) (IMM) }),                      \
 142         ((struct bpf_insn) {                                    \
 143                 .code  = 0, /* zero is reserved opcode */       \
 144                 .dst_reg = 0,                                   \
 145                 .src_reg = 0,                                   \
 146                 .off   = 0,                                     \
 147                 .imm   = ((__u64) (IMM)) >> 32 })
 148
 149 /* pseudo BPF_LD_IMM64 insn used to refer to process-local map_fd */
 150 #define BPF_LD_MAP_FD(DST, MAP_FD)                              \
 151         BPF_LD_IMM64_RAW(DST, BPF_PSEUDO_MAP_FD, MAP_FD)
 152
 153 /* Short form of mov based on type, BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */
 154
 155 #define BPF_MOV64_RAW(TYPE, DST, SRC, IMM)                      \
 156         ((struct bpf_insn) {                                    \
 157                 .code  = BPF_ALU64 | BPF_MOV | BPF_SRC(TYPE),   \
 158                 .dst_reg = DST,                                 \
 159                 .src_reg = SRC,                                 \
 160                 .off   = 0,                                     \
 161                 .imm   = IMM })
 162
 163 #define BPF_MOV32_RAW(TYPE, DST, SRC, IMM)                      \
 164         ((struct bpf_insn) {                                    \
 165                 .code  = BPF_ALU | BPF_MOV | BPF_SRC(TYPE),     \
 166                 .dst_reg = DST,                                 \
 167                 .src_reg = SRC,                                 \
 168                 .off   = 0,                                     \
 169                 .imm   = IMM })
 170
 171 /* Direct packet access, R0 = *(uint *) (skb->data + imm32) */
 172
 173 #define BPF_LD_ABS(SIZE, IMM)                                   \
 174         ((struct bpf_insn) {                                    \
 175                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_ABS,     \
 176                 .dst_reg = 0,                                   \
 177                 .src_reg = 0,                                   \
 178                 .off   = 0,                                     \
 179                 .imm   = IMM })
 180
 181 /* Indirect packet access, R0 = *(uint *) (skb->data + src_reg + imm32) */
 182
 183 #define BPF_LD_IND(SIZE, SRC, IMM)                              \
 184         ((struct bpf_insn) {                                    \
 185                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_IND,     \
 186                 .dst_reg = 0,                                   \
 187                 .src_reg = SRC,                                 \
 188                 .off   = 0,                                     \
 189                 .imm   = IMM })
 190
 191 /* Memory load, dst_reg = *(uint *) (src_reg + off16) */
 192
 193 #define BPF_LDX_MEM(SIZE, DST, SRC, OFF)                        \
 194         ((struct bpf_insn) {                                    \
 195                 .code  = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM,    \
 196                 .dst_reg = DST,                                 \
 197                 .src_reg = SRC,                                 \
 198                 .off   = OFF,                                   \
 199                 .imm   = 0 })
 200
 201 /* Memory store, *(uint *) (dst_reg + off16) = src_reg */
 202
 203 #define BPF_STX_MEM(SIZE, DST, SRC, OFF)                        \
 204         ((struct bpf_insn) {                                    \
 205                 .code  = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM,    \
 206                 .dst_reg = DST,                                 \
 207                 .src_reg = SRC,                                 \
 208                 .off   = OFF,                                   \
 209                 .imm   = 0 })
 210
 211 /* Atomic memory add, *(uint *)(dst_reg + off16) += src_reg */
 212
 213 #define BPF_STX_XADD(SIZE, DST, SRC, OFF)                       \
 214         ((struct bpf_insn) {                                    \
 215                 .code  = BPF_STX | BPF_SIZE(SIZE) | BPF_XADD,   \
 216                 .dst_reg = DST,                                 \
 217                 .src_reg = SRC,                                 \
 218                 .off   = OFF,                                   \
 219                 .imm   = 0 })
 220
 221 /* Memory store, *(uint *) (dst_reg + off16) = imm32 */
 222
 223 #define BPF_ST_MEM(SIZE, DST, OFF, IMM)                         \
 224         ((struct bpf_insn) {                                    \
 225                 .code  = BPF_ST | BPF_SIZE(SIZE) | BPF_MEM,     \
 226                 .dst_reg = DST,                                 \
 227                 .src_reg = 0,                                   \
 228                 .off   = OFF,                                   \
 229                 .imm   = IMM })
 230
 231 /* Conditional jumps against registers, if (dst_reg 'op' src_reg) goto pc + off16 */
 232
 233 #define BPF_JMP_REG(OP, DST, SRC, OFF)                          \
 234         ((struct bpf_insn) {                                    \
 235                 .code  = BPF_JMP | BPF_OP(OP) | BPF_X,          \
 236                 .dst_reg = DST,                                 \
 237                 .src_reg = SRC,                                 \
 238                 .off   = OFF,                                   \
 239                 .imm   = 0 })
 240
 241 /* Conditional jumps against immediates, if (dst_reg 'op' imm32) goto pc + off16 */
 242
 243 #define BPF_JMP_IMM(OP, DST, IMM, OFF)                          \
 244         ((struct bpf_insn) {                                    \
 245                 .code  = BPF_JMP | BPF_OP(OP) | BPF_K,          \
 246                 .dst_reg = DST,                                 \
 247                 .src_reg = 0,                                   \
 248                 .off   = OFF,                                   \
 249                 .imm   = IMM })
 250
 251 /* Function call */
 252
 253 #define BPF_EMIT_CALL(FUNC)                                     \
 254         ((struct bpf_insn) {                                    \
 255                 .code  = BPF_JMP | BPF_CALL,                    \
 256                 .dst_reg = 0,                                   \
 257                 .src_reg = 0,                                   \
 258                 .off   = 0,                                     \
 259                 .imm   = ((FUNC) - __bpf_call_base) })
 260
 261 /* Raw code statement block */
 262
 263 #define BPF_RAW_INSN(CODE, DST, SRC, OFF, IMM)                  \
 264         ((struct bpf_insn) {                                    \
 265                 .code  = CODE,                                  \
 266                 .dst_reg = DST,                                 \
 267                 .src_reg = SRC,                                 \
 268                 .off   = OFF,                                   \
 269                 .imm   = IMM })
 270
 271 /* Program exit */
 272
 273 #define BPF_EXIT_INSN()                                         \
 274         ((struct bpf_insn) {                                    \
 275                 .code  = BPF_JMP | BPF_EXIT,                    \
 276                 .dst_reg = 0,                                   \
 277                 .src_reg = 0,                                   \
 278                 .off   = 0,                                     \
 279                 .imm   = 0 })
 280
 281 /* Internal classic blocks for direct assignment */
 282
 283 #define __BPF_STMT(CODE, K)                                     \
 284         ((struct sock_filter) BPF_STMT(CODE, K))
 285
 286 #define __BPF_JUMP(CODE, K, JT, JF)                             \
 287         ((struct sock_filter) BPF_JUMP(CODE, K, JT, JF))
 288
 289 #define bytes_to_bpf_size(bytes)                                \
 290 ({                                                              \
 291         int bpf_size = -EINVAL;                                 \
 292                                                                 \
 293         if (bytes == sizeof(u8))                                \
 294                 bpf_size = BPF_B;                               \
 295         else if (bytes == sizeof(u16))                          \
 296                 bpf_size = BPF_H;                               \
 297         else if (bytes == sizeof(u32))                          \
 298                 bpf_size = BPF_W;                               \
 299         else if (bytes == sizeof(u64))                          \
 300                 bpf_size = BPF_DW;                              \
 301                                                                 \
 302         bpf_size;                                               \
 303 })
 304
 305 /* Macro to invoke filter function. */
 306 #define SK_RUN_FILTER(filter, ctx) \
 307         (*filter->prog->bpf_func)(ctx, filter->prog->insnsi)
 308
 309 #ifdef CONFIG_COMPAT
 310 /* A struct sock_filter is architecture independent. */
 311 struct compat_sock_fprog {
 312         u16             len;
 313         compat_uptr_t   filter; /* struct sock_filter * */
 314 };
 315 #endif
 316
 317 struct sock_fprog_kern {
 318         u16                     len;
 319         struct sock_filter      *filter;
 320 };
 321
 322 struct bpf_binary_header {
 323         unsigned int pages;
 324         u8 image[];
 325 };
 326
 327 struct bpf_prog {
 328         u16                     pages;          /* Number of allocated pages */
 329         bool                    jited;          /* Is our filter JIT'ed? */
 330         bool                    gpl_compatible; /* Is our filter GPL compatible? */
 331         u32                     len;            /* Number of filter blocks */
 332         enum bpf_prog_type      type;           /* Type of BPF program */
 333         struct bpf_prog_aux     *aux;           /* Auxiliary fields */
 334         struct sock_fprog_kern  *orig_prog;     /* Original BPF program */
 335         unsigned int            (*bpf_func)(const struct sk_buff *skb,
 336                                             const struct bpf_insn *filter);
 337         /* Instructions for interpreter */
 338         union {
 339                 struct sock_filter      insns[0];
 340                 struct bpf_insn         insnsi[0];
 341         };
 342 };
 343
 344 struct sk_filter {
 345         atomic_t        refcnt;
 346         struct rcu_head rcu;
 347         struct bpf_prog *prog;
 348 };
 349
 350 #define BPF_PROG_RUN(filter, ctx)  (*filter->bpf_func)(ctx, filter->insnsi)
 351
 352 static inline unsigned int bpf_prog_size(unsigned int proglen)
 353 {
 354         return max(sizeof(struct bpf_prog),
 355                    offsetof(struct bpf_prog, insns[proglen]));
 356 }
 357
 358 static inline bool bpf_prog_was_classic(const struct bpf_prog *prog)
 359 {
 360         /* When classic BPF programs have been loaded and the arch
 361          * does not have a classic BPF JIT (anymore), they have been
 362          * converted via bpf_migrate_filter() to eBPF and thus always
 363          * have an unspec program type.
 364          */
 365         return prog->type == BPF_PROG_TYPE_UNSPEC;
 366 }
 367
 368 #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
 369
 370 #ifdef CONFIG_DEBUG_SET_MODULE_RONX
 371 static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 372 {
 373         set_memory_ro((unsigned long)fp, fp->pages);
 374 }
 375
 376 static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
 377 {
 378         set_memory_rw((unsigned long)fp, fp->pages);
 379 }
 380 #else
 381 static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 382 {
 383 }
 384
 385 static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
 386 {
 387 }
 388 #endif /* CONFIG_DEBUG_SET_MODULE_RONX */
 389
 390 int sk_filter(struct sock *sk, struct sk_buff *skb);
 391
 392 int bpf_prog_select_runtime(struct bpf_prog *fp);
 393 void bpf_prog_free(struct bpf_prog *fp);
 394
 395 struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags);
 396 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 397                                   gfp_t gfp_extra_flags);
 398 void __bpf_prog_free(struct bpf_prog *fp);
 399
 400 static inline void bpf_prog_unlock_free(struct bpf_prog *fp)
 401 {
 402         bpf_prog_unlock_ro(fp);
 403         __bpf_prog_free(fp);
 404 }
 405
 406 typedef int (*bpf_aux_classic_check_t)(struct sock_filter *filter,
 407                                        unsigned int flen);
 408
 409 int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog);
 410 int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog,
 411                               bpf_aux_classic_check_t trans);
 412 void bpf_prog_destroy(struct bpf_prog *fp);
 413
 414 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 415 int sk_attach_bpf(u32 ufd, struct sock *sk);
 416 int sk_detach_filter(struct sock *sk);
 417 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 418                   unsigned int len);
 419
 420 bool sk_filter_charge(struct sock *sk, struct sk_filter *fp);
 421 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 422
 423 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 424 void bpf_int_jit_compile(struct bpf_prog *fp);
 425 bool bpf_helper_changes_skb_data(void *func);
 426
 427 #ifdef CONFIG_BPF_JIT
 428 typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size);
 429
 430 struct bpf_binary_header *
 431 bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
 432                      unsigned int alignment,
 433                      bpf_jit_fill_hole_t bpf_fill_ill_insns);
 434 void bpf_jit_binary_free(struct bpf_binary_header *hdr);
 435
 436 void bpf_jit_compile(struct bpf_prog *fp);
 437 void bpf_jit_free(struct bpf_prog *fp);
 438
 439 static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
 440                                 u32 pass, void *image)
 441 {
 442         pr_err("flen=%u proglen=%u pass=%u image=%pK from=%s pid=%d\n", flen,
 443                proglen, pass, image, current->comm, task_pid_nr(current));
 444
 445         if (image)
 446                 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET,
 447                                16, 1, image, proglen, false);
 448 }
 449 #else
 450 static inline void bpf_jit_compile(struct bpf_prog *fp)
 451 {
 452 }
 453
 454 static inline void bpf_jit_free(struct bpf_prog *fp)
 455 {
 456         bpf_prog_unlock_free(fp);
 457 }
 458 #endif /* CONFIG_BPF_JIT */
 459
 460 #define BPF_ANC         BIT(15)
 461
 462 static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
 463 {
 464         BUG_ON(ftest->code & BPF_ANC);
 465
 466         switch (ftest->code) {
 467         case BPF_LD | BPF_W | BPF_ABS:
 468         case BPF_LD | BPF_H | BPF_ABS:
 469         case BPF_LD | BPF_B | BPF_ABS:
 470 #define BPF_ANCILLARY(CODE)     case SKF_AD_OFF + SKF_AD_##CODE:        \
 471                                 return BPF_ANC | SKF_AD_##CODE
 472                 switch (ftest->k) {
 473                 BPF_ANCILLARY(PROTOCOL);
 474                 BPF_ANCILLARY(PKTTYPE);
 475                 BPF_ANCILLARY(IFINDEX);
 476                 BPF_ANCILLARY(NLATTR);
 477                 BPF_ANCILLARY(NLATTR_NEST);
 478                 BPF_ANCILLARY(MARK);
 479                 BPF_ANCILLARY(QUEUE);
 480                 BPF_ANCILLARY(HATYPE);
 481                 BPF_ANCILLARY(RXHASH);
 482                 BPF_ANCILLARY(CPU);
 483                 BPF_ANCILLARY(ALU_XOR_X);
 484                 BPF_ANCILLARY(VLAN_TAG);
 485                 BPF_ANCILLARY(VLAN_TAG_PRESENT);
 486                 BPF_ANCILLARY(PAY_OFFSET);
 487                 BPF_ANCILLARY(RANDOM);
 488                 BPF_ANCILLARY(VLAN_TPID);
 489                 }
 490                 /* Fallthrough. */
 491         default:
 492                 return ftest->code;
 493         }
 494 }
 495
 496 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb,
 497                                            int k, unsigned int size);
 498
 499 static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
 500                                      unsigned int size, void *buffer)
 501 {
 502         if (k >= 0)
 503                 return skb_header_pointer(skb, k, size, buffer);
 504
 505         return bpf_internal_load_pointer_neg_helper(skb, k, size);
 506 }
 507
 508 static inline int bpf_tell_extensions(void)
 509 {
 510         return SKF_AD_MAX;
 511 }
 512
 513 #endif /* __LINUX_FILTER_H__ */