include/linux/filter.h

   1 /*
   2  * Linux Socket Filter Data Structures
   3  */
   4
   5 #ifndef __LINUX_FILTER_H__
   6 #define __LINUX_FILTER_H__
   7
   8 /*
   9  * Current version of the filter code architecture.
  10  */
  11 #define BPF_MAJOR_VERSION 1
  12 #define BPF_MINOR_VERSION 1
  13
  14 /*
  15  *      Try and keep these values and structures similar to BSD, especially
  16  *      the BPF code definitions which need to match so you can share filters
  17  */
  18
  19 struct sock_filter      /* Filter block */
  20 {
  21         __u16   code;   /* Actual filter code */
  22         __u8    jt;     /* Jump true */
  23         __u8    jf;     /* Jump false */
  24         __u32   k;      /* Generic multiuse field */
  25 };
  26
  27 struct sock_fprog       /* Required for SO_ATTACH_FILTER. */
  28 {
  29         unsigned short          len;    /* Number of filter blocks */
  30         struct sock_filter      *filter;
  31 };
  32
  33 #ifdef __KERNEL__
  34 struct sk_filter
  35 {
  36         atomic_t                refcnt;
  37         unsigned int            len;    /* Number of filter blocks */
  38         struct sock_filter      insns[0];
  39 };
  40
  41 static inline unsigned int sk_filter_len(struct sk_filter *fp)
  42 {
  43         return fp->len*sizeof(struct sock_filter) + sizeof(*fp);
  44 }
  45 #endif
  46
  47 /*
  48  * Instruction classes
  49  */
  50
  51 #define BPF_CLASS(code) ((code) & 0x07)
  52 #define         BPF_LD          0x00
  53 #define         BPF_LDX         0x01
  54 #define         BPF_ST          0x02
  55 #define         BPF_STX         0x03
  56 #define         BPF_ALU         0x04
  57 #define         BPF_JMP         0x05
  58 #define         BPF_RET         0x06
  59 #define         BPF_MISC        0x07
  60
  61 /* ld/ldx fields */
  62 #define BPF_SIZE(code)  ((code) & 0x18)
  63 #define         BPF_W           0x00
  64 #define         BPF_H           0x08
  65 #define         BPF_B           0x10
  66 #define BPF_MODE(code)  ((code) & 0xe0)
  67 #define         BPF_IMM         0x00
  68 #define         BPF_ABS         0x20
  69 #define         BPF_IND         0x40
  70 #define         BPF_MEM         0x60
  71 #define         BPF_LEN         0x80
  72 #define         BPF_MSH         0xa0
  73
  74 /* alu/jmp fields */
  75 #define BPF_OP(code)    ((code) & 0xf0)
  76 #define         BPF_ADD         0x00
  77 #define         BPF_SUB         0x10
  78 #define         BPF_MUL         0x20
  79 #define         BPF_DIV         0x30
  80 #define         BPF_OR          0x40
  81 #define         BPF_AND         0x50
  82 #define         BPF_LSH         0x60
  83 #define         BPF_RSH         0x70
  84 #define         BPF_NEG         0x80
  85 #define         BPF_JA          0x00
  86 #define         BPF_JEQ         0x10
  87 #define         BPF_JGT         0x20
  88 #define         BPF_JGE         0x30
  89 #define         BPF_JSET        0x40
  90 #define BPF_SRC(code)   ((code) & 0x08)
  91 #define         BPF_K           0x00
  92 #define         BPF_X           0x08
  93
  94 /* ret - BPF_K and BPF_X also apply */
  95 #define BPF_RVAL(code)  ((code) & 0x18)
  96 #define         BPF_A           0x10
  97
  98 /* misc */
  99 #define BPF_MISCOP(code) ((code) & 0xf8)
 100 #define         BPF_TAX         0x00
 101 #define         BPF_TXA         0x80
 102
 103 #ifndef BPF_MAXINSNS
 104 #define BPF_MAXINSNS 4096
 105 #endif
 106
 107 /*
 108  * Macros for filter block array initializers.
 109  */
 110 #ifndef BPF_STMT
 111 #define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
 112 #endif
 113 #ifndef BPF_JUMP
 114 #define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
 115 #endif
 116
 117 /*
 118  * Number of scratch memory words for: BPF_ST and BPF_STX
 119  */
 120 #define BPF_MEMWORDS 16
 121
 122 /* RATIONALE. Negative offsets are invalid in BPF.
 123    We use them to reference ancillary data.
 124    Unlike introduction new instructions, it does not break
 125    existing compilers/optimizers.
 126  */
 127 #define SKF_AD_OFF    (-0x1000)
 128 #define SKF_AD_PROTOCOL 0
 129 #define SKF_AD_PKTTYPE  4
 130 #define SKF_AD_IFINDEX  8
 131 #define SKF_AD_MAX      12
 132 #define SKF_NET_OFF   (-0x100000)
 133 #define SKF_LL_OFF    (-0x200000)
 134
 135 #ifdef __KERNEL__
 136 extern int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen);
 137 extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 138 #endif /* __KERNEL__ */
 139
 140 #endif /* __LINUX_FILTER_H__ */