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 #include <net/sch_generic.h>
  17
  18 #include <asm/cacheflush.h>
  19
  20 #include <uapi/linux/filter.h>
  21 #include <uapi/linux/bpf.h>
  22
  23 struct sk_buff;
  24 struct sock;
  25 struct seccomp_data;
  26 struct bpf_prog_aux;
  27
  28 /* ArgX, context and stack frame pointer register positions. Note,
  29  * Arg1, Arg2, Arg3, etc are used as argument mappings of function
  30  * calls in BPF_CALL instruction.
  31  */
  32 #define BPF_REG_ARG1    BPF_REG_1
  33 #define BPF_REG_ARG2    BPF_REG_2
  34 #define BPF_REG_ARG3    BPF_REG_3
  35 #define BPF_REG_ARG4    BPF_REG_4
  36 #define BPF_REG_ARG5    BPF_REG_5
  37 #define BPF_REG_CTX     BPF_REG_6
  38 #define BPF_REG_FP      BPF_REG_10
  39
  40 /* Additional register mappings for converted user programs. */
  41 #define BPF_REG_A       BPF_REG_0
  42 #define BPF_REG_X       BPF_REG_7
  43 #define BPF_REG_TMP     BPF_REG_8
  44
  45 /* BPF program can access up to 512 bytes of stack space. */
  46 #define MAX_BPF_STACK   512
  47
  48 /* Helper macros for filter block array initializers. */
  49
  50 /* ALU ops on registers, bpf_add|sub|...: dst_reg += src_reg */
  51
  52 #define BPF_ALU64_REG(OP, DST, SRC)                             \
  53         ((struct bpf_insn) {                                    \
  54                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_X,        \
  55                 .dst_reg = DST,                                 \
  56                 .src_reg = SRC,                                 \
  57                 .off   = 0,                                     \
  58                 .imm   = 0 })
  59
  60 #define BPF_ALU32_REG(OP, DST, SRC)                             \
  61         ((struct bpf_insn) {                                    \
  62                 .code  = BPF_ALU | BPF_OP(OP) | BPF_X,          \
  63                 .dst_reg = DST,                                 \
  64                 .src_reg = SRC,                                 \
  65                 .off   = 0,                                     \
  66                 .imm   = 0 })
  67
  68 /* ALU ops on immediates, bpf_add|sub|...: dst_reg += imm32 */
  69
  70 #define BPF_ALU64_IMM(OP, DST, IMM)                             \
  71         ((struct bpf_insn) {                                    \
  72                 .code  = BPF_ALU64 | BPF_OP(OP) | BPF_K,        \
  73                 .dst_reg = DST,                                 \
  74                 .src_reg = 0,                                   \
  75                 .off   = 0,                                     \
  76                 .imm   = IMM })
  77
  78 #define BPF_ALU32_IMM(OP, DST, IMM)                             \
  79         ((struct bpf_insn) {                                    \
  80                 .code  = BPF_ALU | BPF_OP(OP) | BPF_K,          \
  81                 .dst_reg = DST,                                 \
  82                 .src_reg = 0,                                   \
  83                 .off   = 0,                                     \
  84                 .imm   = IMM })
  85
  86 /* Endianess conversion, cpu_to_{l,b}e(), {l,b}e_to_cpu() */
  87
  88 #define BPF_ENDIAN(TYPE, DST, LEN)                              \
  89         ((struct bpf_insn) {                                    \
  90                 .code  = BPF_ALU | BPF_END | BPF_SRC(TYPE),     \
  91                 .dst_reg = DST,                                 \
  92                 .src_reg = 0,                                   \
  93                 .off   = 0,                                     \
  94                 .imm   = LEN })
  95
  96 /* Short form of mov, dst_reg = src_reg */
  97
  98 #define BPF_MOV64_REG(DST, SRC)                                 \
  99         ((struct bpf_insn) {                                    \
 100                 .code  = BPF_ALU64 | BPF_MOV | BPF_X,           \
 101                 .dst_reg = DST,                                 \
 102                 .src_reg = SRC,                                 \
 103                 .off   = 0,                                     \
 104                 .imm   = 0 })
 105
 106 #define BPF_MOV32_REG(DST, SRC)                                 \
 107         ((struct bpf_insn) {                                    \
 108                 .code  = BPF_ALU | BPF_MOV | BPF_X,             \
 109                 .dst_reg = DST,                                 \
 110                 .src_reg = SRC,                                 \
 111                 .off   = 0,                                     \
 112                 .imm   = 0 })
 113
 114 /* Short form of mov, dst_reg = imm32 */
 115
 116 #define BPF_MOV64_IMM(DST, IMM)                                 \
 117         ((struct bpf_insn) {                                    \
 118                 .code  = BPF_ALU64 | BPF_MOV | BPF_K,           \
 119                 .dst_reg = DST,                                 \
 120                 .src_reg = 0,                                   \
 121                 .off   = 0,                                     \
 122                 .imm   = IMM })
 123
 124 #define BPF_MOV32_IMM(DST, IMM)                                 \
 125         ((struct bpf_insn) {                                    \
 126                 .code  = BPF_ALU | BPF_MOV | BPF_K,             \
 127                 .dst_reg = DST,                                 \
 128                 .src_reg = 0,                                   \
 129                 .off   = 0,                                     \
 130                 .imm   = IMM })
 131
 132 /* BPF_LD_IMM64 macro encodes single 'load 64-bit immediate' insn */
 133 #define BPF_LD_IMM64(DST, IMM)                                  \
 134         BPF_LD_IMM64_RAW(DST, 0, IMM)
 135
 136 #define BPF_LD_IMM64_RAW(DST, SRC, IMM)                         \
 137         ((struct bpf_insn) {                                    \
 138                 .code  = BPF_LD | BPF_DW | BPF_IMM,             \
 139                 .dst_reg = DST,                                 \
 140                 .src_reg = SRC,                                 \
 141                 .off   = 0,                                     \
 142                 .imm   = (__u32) (IMM) }),                      \
 143         ((struct bpf_insn) {                                    \
 144                 .code  = 0, /* zero is reserved opcode */       \
 145                 .dst_reg = 0,                                   \
 146                 .src_reg = 0,                                   \
 147                 .off   = 0,                                     \
 148                 .imm   = ((__u64) (IMM)) >> 32 })
 149
 150 /* pseudo BPF_LD_IMM64 insn used to refer to process-local map_fd */
 151 #define BPF_LD_MAP_FD(DST, MAP_FD)                              \
 152         BPF_LD_IMM64_RAW(DST, BPF_PSEUDO_MAP_FD, MAP_FD)
 153
 154 /* Short form of mov based on type, BPF_X: dst_reg = src_reg, BPF_K: dst_reg = imm32 */
 155
 156 #define BPF_MOV64_RAW(TYPE, DST, SRC, IMM)                      \
 157         ((struct bpf_insn) {                                    \
 158                 .code  = BPF_ALU64 | BPF_MOV | BPF_SRC(TYPE),   \
 159                 .dst_reg = DST,                                 \
 160                 .src_reg = SRC,                                 \
 161                 .off   = 0,                                     \
 162                 .imm   = IMM })
 163
 164 #define BPF_MOV32_RAW(TYPE, DST, SRC, IMM)                      \
 165         ((struct bpf_insn) {                                    \
 166                 .code  = BPF_ALU | BPF_MOV | BPF_SRC(TYPE),     \
 167                 .dst_reg = DST,                                 \
 168                 .src_reg = SRC,                                 \
 169                 .off   = 0,                                     \
 170                 .imm   = IMM })
 171
 172 /* Direct packet access, R0 = *(uint *) (skb->data + imm32) */
 173
 174 #define BPF_LD_ABS(SIZE, IMM)                                   \
 175         ((struct bpf_insn) {                                    \
 176                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_ABS,     \
 177                 .dst_reg = 0,                                   \
 178                 .src_reg = 0,                                   \
 179                 .off   = 0,                                     \
 180                 .imm   = IMM })
 181
 182 /* Indirect packet access, R0 = *(uint *) (skb->data + src_reg + imm32) */
 183
 184 #define BPF_LD_IND(SIZE, SRC, IMM)                              \
 185         ((struct bpf_insn) {                                    \
 186                 .code  = BPF_LD | BPF_SIZE(SIZE) | BPF_IND,     \
 187                 .dst_reg = 0,                                   \
 188                 .src_reg = SRC,                                 \
 189                 .off   = 0,                                     \
 190                 .imm   = IMM })
 191
 192 /* Memory load, dst_reg = *(uint *) (src_reg + off16) */
 193
 194 #define BPF_LDX_MEM(SIZE, DST, SRC, OFF)                        \
 195         ((struct bpf_insn) {                                    \
 196                 .code  = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM,    \
 197                 .dst_reg = DST,                                 \
 198                 .src_reg = SRC,                                 \
 199                 .off   = OFF,                                   \
 200                 .imm   = 0 })
 201
 202 /* Memory store, *(uint *) (dst_reg + off16) = src_reg */
 203
 204 #define BPF_STX_MEM(SIZE, DST, SRC, OFF)                        \
 205         ((struct bpf_insn) {                                    \
 206                 .code  = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM,    \
 207                 .dst_reg = DST,                                 \
 208                 .src_reg = SRC,                                 \
 209                 .off   = OFF,                                   \
 210                 .imm   = 0 })
 211
 212 /* Atomic memory add, *(uint *)(dst_reg + off16) += src_reg */
 213
 214 #define BPF_STX_XADD(SIZE, DST, SRC, OFF)                       \
 215         ((struct bpf_insn) {                                    \
 216                 .code  = BPF_STX | BPF_SIZE(SIZE) | BPF_XADD,   \
 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 /* Internal classic blocks for direct assignment */
 283
 284 #define __BPF_STMT(CODE, K)                                     \
 285         ((struct sock_filter) BPF_STMT(CODE, K))
 286
 287 #define __BPF_JUMP(CODE, K, JT, JF)                             \
 288         ((struct sock_filter) BPF_JUMP(CODE, K, JT, JF))
 289
 290 #define bytes_to_bpf_size(bytes)                                \
 291 ({                                                              \
 292         int bpf_size = -EINVAL;                                 \
 293                                                                 \
 294         if (bytes == sizeof(u8))                                \
 295                 bpf_size = BPF_B;                               \
 296         else if (bytes == sizeof(u16))                          \
 297                 bpf_size = BPF_H;                               \
 298         else if (bytes == sizeof(u32))                          \
 299                 bpf_size = BPF_W;                               \
 300         else if (bytes == sizeof(u64))                          \
 301                 bpf_size = BPF_DW;                              \
 302                                                                 \
 303         bpf_size;                                               \
 304 })
 305
 306 #ifdef CONFIG_COMPAT
 307 /* A struct sock_filter is architecture independent. */
 308 struct compat_sock_fprog {
 309         u16             len;
 310         compat_uptr_t   filter; /* struct sock_filter * */
 311 };
 312 #endif
 313
 314 struct sock_fprog_kern {
 315         u16                     len;
 316         struct sock_filter      *filter;
 317 };
 318
 319 struct bpf_binary_header {
 320         unsigned int pages;
 321         u8 image[];
 322 };
 323
 324 struct bpf_prog {
 325         u16                     pages;          /* Number of allocated pages */
 326         kmemcheck_bitfield_begin(meta);
 327         u16                     jited:1,        /* Is our filter JIT'ed? */
 328                                 gpl_compatible:1, /* Is filter GPL compatible? */
 329                                 cb_access:1,    /* Is control block accessed? */
 330                                 dst_needed:1;   /* Do we need dst entry? */
 331         kmemcheck_bitfield_end(meta);
 332         u32                     len;            /* Number of filter blocks */
 333         enum bpf_prog_type      type;           /* Type of BPF program */
 334         struct bpf_prog_aux     *aux;           /* Auxiliary fields */
 335         struct sock_fprog_kern  *orig_prog;     /* Original BPF program */
 336         unsigned int            (*bpf_func)(const struct sk_buff *skb,
 337                                             const struct bpf_insn *filter);
 338         /* Instructions for interpreter */
 339         union {
 340                 struct sock_filter      insns[0];
 341                 struct bpf_insn         insnsi[0];
 342         };
 343 };
 344
 345 struct sk_filter {
 346         atomic_t        refcnt;
 347         struct rcu_head rcu;
 348         struct bpf_prog *prog;
 349 };
 350
 351 #define BPF_PROG_RUN(filter, ctx)  (*filter->bpf_func)(ctx, filter->insnsi)
 352
 353 static inline u32 bpf_prog_run_save_cb(const struct bpf_prog *prog,
 354                                        struct sk_buff *skb)
 355 {
 356         u8 *cb_data = qdisc_skb_cb(skb)->data;
 357         u8 saved_cb[QDISC_CB_PRIV_LEN];
 358         u32 res;
 359
 360         BUILD_BUG_ON(FIELD_SIZEOF(struct __sk_buff, cb) !=
 361                      QDISC_CB_PRIV_LEN);
 362
 363         if (unlikely(prog->cb_access)) {
 364                 memcpy(saved_cb, cb_data, sizeof(saved_cb));
 365                 memset(cb_data, 0, sizeof(saved_cb));
 366         }
 367
 368         res = BPF_PROG_RUN(prog, skb);
 369
 370         if (unlikely(prog->cb_access))
 371                 memcpy(cb_data, saved_cb, sizeof(saved_cb));
 372
 373         return res;
 374 }
 375
 376 static inline u32 bpf_prog_run_clear_cb(const struct bpf_prog *prog,
 377                                         struct sk_buff *skb)
 378 {
 379         u8 *cb_data = qdisc_skb_cb(skb)->data;
 380
 381         if (unlikely(prog->cb_access))
 382                 memset(cb_data, 0, QDISC_CB_PRIV_LEN);
 383         return BPF_PROG_RUN(prog, skb);
 384 }
 385
 386 static inline unsigned int bpf_prog_size(unsigned int proglen)
 387 {
 388         return max(sizeof(struct bpf_prog),
 389                    offsetof(struct bpf_prog, insns[proglen]));
 390 }
 391
 392 static inline bool bpf_prog_was_classic(const struct bpf_prog *prog)
 393 {
 394         /* When classic BPF programs have been loaded and the arch
 395          * does not have a classic BPF JIT (anymore), they have been
 396          * converted via bpf_migrate_filter() to eBPF and thus always
 397          * have an unspec program type.
 398          */
 399         return prog->type == BPF_PROG_TYPE_UNSPEC;
 400 }
 401
 402 #define bpf_classic_proglen(fprog) (fprog->len * sizeof(fprog->filter[0]))
 403
 404 #ifdef CONFIG_DEBUG_SET_MODULE_RONX
 405 static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 406 {
 407         set_memory_ro((unsigned long)fp, fp->pages);
 408 }
 409
 410 static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
 411 {
 412         set_memory_rw((unsigned long)fp, fp->pages);
 413 }
 414 #else
 415 static inline void bpf_prog_lock_ro(struct bpf_prog *fp)
 416 {
 417 }
 418
 419 static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
 420 {
 421 }
 422 #endif /* CONFIG_DEBUG_SET_MODULE_RONX */
 423
 424 int sk_filter(struct sock *sk, struct sk_buff *skb);
 425
 426 int bpf_prog_select_runtime(struct bpf_prog *fp);
 427 void bpf_prog_free(struct bpf_prog *fp);
 428
 429 struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags);
 430 struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 431                                   gfp_t gfp_extra_flags);
 432 void __bpf_prog_free(struct bpf_prog *fp);
 433
 434 static inline void bpf_prog_unlock_free(struct bpf_prog *fp)
 435 {
 436         bpf_prog_unlock_ro(fp);
 437         __bpf_prog_free(fp);
 438 }
 439
 440 typedef int (*bpf_aux_classic_check_t)(struct sock_filter *filter,
 441                                        unsigned int flen);
 442
 443 int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog);
 444 int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog,
 445                               bpf_aux_classic_check_t trans, bool save_orig);
 446 void bpf_prog_destroy(struct bpf_prog *fp);
 447
 448 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 449 int sk_attach_bpf(u32 ufd, struct sock *sk);
 450 int sk_detach_filter(struct sock *sk);
 451 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
 452                   unsigned int len);
 453
 454 bool sk_filter_charge(struct sock *sk, struct sk_filter *fp);
 455 void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp);
 456
 457 u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
 458 void bpf_int_jit_compile(struct bpf_prog *fp);
 459 bool bpf_helper_changes_skb_data(void *func);
 460
 461 #ifdef CONFIG_BPF_JIT
 462 typedef void (*bpf_jit_fill_hole_t)(void *area, unsigned int size);
 463
 464 struct bpf_binary_header *
 465 bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr,
 466                      unsigned int alignment,
 467                      bpf_jit_fill_hole_t bpf_fill_ill_insns);
 468 void bpf_jit_binary_free(struct bpf_binary_header *hdr);
 469
 470 void bpf_jit_compile(struct bpf_prog *fp);
 471 void bpf_jit_free(struct bpf_prog *fp);
 472
 473 static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
 474                                 u32 pass, void *image)
 475 {
 476         pr_err("flen=%u proglen=%u pass=%u image=%pK from=%s pid=%d\n", flen,
 477                proglen, pass, image, current->comm, task_pid_nr(current));
 478
 479         if (image)
 480                 print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET,
 481                                16, 1, image, proglen, false);
 482 }
 483 #else
 484 static inline void bpf_jit_compile(struct bpf_prog *fp)
 485 {
 486 }
 487
 488 static inline void bpf_jit_free(struct bpf_prog *fp)
 489 {
 490         bpf_prog_unlock_free(fp);
 491 }
 492 #endif /* CONFIG_BPF_JIT */
 493
 494 #define BPF_ANC         BIT(15)
 495
 496 static inline u16 bpf_anc_helper(const struct sock_filter *ftest)
 497 {
 498         BUG_ON(ftest->code & BPF_ANC);
 499
 500         switch (ftest->code) {
 501         case BPF_LD | BPF_W | BPF_ABS:
 502         case BPF_LD | BPF_H | BPF_ABS:
 503         case BPF_LD | BPF_B | BPF_ABS:
 504 #define BPF_ANCILLARY(CODE)     case SKF_AD_OFF + SKF_AD_##CODE:        \
 505                                 return BPF_ANC | SKF_AD_##CODE
 506                 switch (ftest->k) {
 507                 BPF_ANCILLARY(PROTOCOL);
 508                 BPF_ANCILLARY(PKTTYPE);
 509                 BPF_ANCILLARY(IFINDEX);
 510                 BPF_ANCILLARY(NLATTR);
 511                 BPF_ANCILLARY(NLATTR_NEST);
 512                 BPF_ANCILLARY(MARK);
 513                 BPF_ANCILLARY(QUEUE);
 514                 BPF_ANCILLARY(HATYPE);
 515                 BPF_ANCILLARY(RXHASH);
 516                 BPF_ANCILLARY(CPU);
 517                 BPF_ANCILLARY(ALU_XOR_X);
 518                 BPF_ANCILLARY(VLAN_TAG);
 519                 BPF_ANCILLARY(VLAN_TAG_PRESENT);
 520                 BPF_ANCILLARY(PAY_OFFSET);
 521                 BPF_ANCILLARY(RANDOM);
 522                 BPF_ANCILLARY(VLAN_TPID);
 523                 }
 524                 /* Fallthrough. */
 525         default:
 526                 return ftest->code;
 527         }
 528 }
 529
 530 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb,
 531                                            int k, unsigned int size);
 532
 533 static inline void *bpf_load_pointer(const struct sk_buff *skb, int k,
 534                                      unsigned int size, void *buffer)
 535 {
 536         if (k >= 0)
 537                 return skb_header_pointer(skb, k, size, buffer);
 538
 539         return bpf_internal_load_pointer_neg_helper(skb, k, size);
 540 }
 541
 542 static inline int bpf_tell_extensions(void)
 543 {
 544         return SKF_AD_MAX;
 545 }
 546
 547 #endif /* __LINUX_FILTER_H__ */