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