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 #include <linux/compiler.h>
   9
  10 /*
  11  * Current version of the filter code architecture.
  12  */
  13 #define BPF_MAJOR_VERSION 1
  14 #define BPF_MINOR_VERSION 1
  15
  16 /*
  17  *      Try and keep these values and structures similar to BSD, especially
  18  *      the BPF code definitions which need to match so you can share filters
  19  */
  20
  21 struct sock_filter      /* Filter block */
  22 {
  23         __u16   code;   /* Actual filter code */
  24         __u8    jt;     /* Jump true */
  25         __u8    jf;     /* Jump false */
  26         __u32   k;      /* Generic multiuse field */
  27 };
  28
  29 struct sock_fprog       /* Required for SO_ATTACH_FILTER. */
  30 {
  31         unsigned short          len;    /* Number of filter blocks */
  32         struct sock_filter __user *filter;
  33 };
  34
  35 #ifdef __KERNEL__
  36 struct sk_filter
  37 {
  38         atomic_t                refcnt;
  39         unsigned int            len;    /* Number of filter blocks */
  40         struct sock_filter      insns[0];
  41 };
  42
  43 static inline unsigned int sk_filter_len(struct sk_filter *fp)
  44 {
  45         return fp->len*sizeof(struct sock_filter) + sizeof(*fp);
  46 }
  47 #endif
  48
  49 /*
  50  * Instruction classes
  51  */
  52
  53 #define BPF_CLASS(code) ((code) & 0x07)
  54 #define         BPF_LD          0x00
  55 #define         BPF_LDX         0x01
  56 #define         BPF_ST          0x02
  57 #define         BPF_STX         0x03
  58 #define         BPF_ALU         0x04
  59 #define         BPF_JMP         0x05
  60 #define         BPF_RET         0x06
  61 #define         BPF_MISC        0x07
  62
  63 /* ld/ldx fields */
  64 #define BPF_SIZE(code)  ((code) & 0x18)
  65 #define         BPF_W           0x00
  66 #define         BPF_H           0x08
  67 #define         BPF_B           0x10
  68 #define BPF_MODE(code)  ((code) & 0xe0)
  69 #define         BPF_IMM         0x00
  70 #define         BPF_ABS         0x20
  71 #define         BPF_IND         0x40
  72 #define         BPF_MEM         0x60
  73 #define         BPF_LEN         0x80
  74 #define         BPF_MSH         0xa0
  75
  76 /* alu/jmp fields */
  77 #define BPF_OP(code)    ((code) & 0xf0)
  78 #define         BPF_ADD         0x00
  79 #define         BPF_SUB         0x10
  80 #define         BPF_MUL         0x20
  81 #define         BPF_DIV         0x30
  82 #define         BPF_OR          0x40
  83 #define         BPF_AND         0x50
  84 #define         BPF_LSH         0x60
  85 #define         BPF_RSH         0x70
  86 #define         BPF_NEG         0x80
  87 #define         BPF_JA          0x00
  88 #define         BPF_JEQ         0x10
  89 #define         BPF_JGT         0x20
  90 #define         BPF_JGE         0x30
  91 #define         BPF_JSET        0x40
  92 #define BPF_SRC(code)   ((code) & 0x08)
  93 #define         BPF_K           0x00
  94 #define         BPF_X           0x08
  95
  96 /* ret - BPF_K and BPF_X also apply */
  97 #define BPF_RVAL(code)  ((code) & 0x18)
  98 #define         BPF_A           0x10
  99
 100 /* misc */
 101 #define BPF_MISCOP(code) ((code) & 0xf8)
 102 #define         BPF_TAX         0x00
 103 #define         BPF_TXA         0x80
 104
 105 #ifndef BPF_MAXINSNS
 106 #define BPF_MAXINSNS 4096
 107 #endif
 108
 109 /*
 110  * Macros for filter block array initializers.
 111  */
 112 #ifndef BPF_STMT
 113 #define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
 114 #endif
 115 #ifndef BPF_JUMP
 116 #define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
 117 #endif
 118
 119 /*
 120  * Number of scratch memory words for: BPF_ST and BPF_STX
 121  */
 122 #define BPF_MEMWORDS 16
 123
 124 /* RATIONALE. Negative offsets are invalid in BPF.
 125    We use them to reference ancillary data.
 126    Unlike introduction new instructions, it does not break
 127    existing compilers/optimizers.
 128  */
 129 #define SKF_AD_OFF    (-0x1000)
 130 #define SKF_AD_PROTOCOL 0
 131 #define SKF_AD_PKTTYPE  4
 132 #define SKF_AD_IFINDEX  8
 133 #define SKF_AD_MAX      12
 134 #define SKF_NET_OFF   (-0x100000)
 135 #define SKF_LL_OFF    (-0x200000)
 136
 137 #ifdef __KERNEL__
 138 extern int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen);
 139 extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 140 extern int sk_chk_filter(struct sock_filter *filter, int flen);
 141 #endif /* __KERNEL__ */
 142
 143 #endif /* __LINUX_FILTER_H__ */