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 #include <linux/types.h>
  10
  11 #ifdef __KERNEL__
  12 #include <asm/atomic.h>
  13 #endif
  14
  15 /*
  16  * Current version of the filter code architecture.
  17  */
  18 #define BPF_MAJOR_VERSION 1
  19 #define BPF_MINOR_VERSION 1
  20
  21 /*
  22  *      Try and keep these values and structures similar to BSD, especially
  23  *      the BPF code definitions which need to match so you can share filters
  24  */
  25
  26 struct sock_filter      /* Filter block */
  27 {
  28         __u16   code;   /* Actual filter code */
  29         __u8    jt;     /* Jump true */
  30         __u8    jf;     /* Jump false */
  31         __u32   k;      /* Generic multiuse field */
  32 };
  33
  34 struct sock_fprog       /* Required for SO_ATTACH_FILTER. */
  35 {
  36         unsigned short          len;    /* Number of filter blocks */
  37         struct sock_filter __user *filter;
  38 };
  39
  40 #ifdef __KERNEL__
  41 struct sk_filter
  42 {
  43         atomic_t                refcnt;
  44         unsigned int            len;    /* Number of filter blocks */
  45         struct rcu_head         rcu;
  46         struct sock_filter      insns[0];
  47 };
  48
  49 static inline unsigned int sk_filter_len(struct sk_filter *fp)
  50 {
  51         return fp->len*sizeof(struct sock_filter) + sizeof(*fp);
  52 }
  53 #endif
  54
  55 /*
  56  * Instruction classes
  57  */
  58
  59 #define BPF_CLASS(code) ((code) & 0x07)
  60 #define         BPF_LD          0x00
  61 #define         BPF_LDX         0x01
  62 #define         BPF_ST          0x02
  63 #define         BPF_STX         0x03
  64 #define         BPF_ALU         0x04
  65 #define         BPF_JMP         0x05
  66 #define         BPF_RET         0x06
  67 #define         BPF_MISC        0x07
  68
  69 /* ld/ldx fields */
  70 #define BPF_SIZE(code)  ((code) & 0x18)
  71 #define         BPF_W           0x00
  72 #define         BPF_H           0x08
  73 #define         BPF_B           0x10
  74 #define BPF_MODE(code)  ((code) & 0xe0)
  75 #define         BPF_IMM         0x00
  76 #define         BPF_ABS         0x20
  77 #define         BPF_IND         0x40
  78 #define         BPF_MEM         0x60
  79 #define         BPF_LEN         0x80
  80 #define         BPF_MSH         0xa0
  81
  82 /* alu/jmp fields */
  83 #define BPF_OP(code)    ((code) & 0xf0)
  84 #define         BPF_ADD         0x00
  85 #define         BPF_SUB         0x10
  86 #define         BPF_MUL         0x20
  87 #define         BPF_DIV         0x30
  88 #define         BPF_OR          0x40
  89 #define         BPF_AND         0x50
  90 #define         BPF_LSH         0x60
  91 #define         BPF_RSH         0x70
  92 #define         BPF_NEG         0x80
  93 #define         BPF_JA          0x00
  94 #define         BPF_JEQ         0x10
  95 #define         BPF_JGT         0x20
  96 #define         BPF_JGE         0x30
  97 #define         BPF_JSET        0x40
  98 #define BPF_SRC(code)   ((code) & 0x08)
  99 #define         BPF_K           0x00
 100 #define         BPF_X           0x08
 101
 102 /* ret - BPF_K and BPF_X also apply */
 103 #define BPF_RVAL(code)  ((code) & 0x18)
 104 #define         BPF_A           0x10
 105
 106 /* misc */
 107 #define BPF_MISCOP(code) ((code) & 0xf8)
 108 #define         BPF_TAX         0x00
 109 #define         BPF_TXA         0x80
 110
 111 #ifndef BPF_MAXINSNS
 112 #define BPF_MAXINSNS 4096
 113 #endif
 114
 115 /*
 116  * Macros for filter block array initializers.
 117  */
 118 #ifndef BPF_STMT
 119 #define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
 120 #endif
 121 #ifndef BPF_JUMP
 122 #define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
 123 #endif
 124
 125 /*
 126  * Number of scratch memory words for: BPF_ST and BPF_STX
 127  */
 128 #define BPF_MEMWORDS 16
 129
 130 /* RATIONALE. Negative offsets are invalid in BPF.
 131    We use them to reference ancillary data.
 132    Unlike introduction new instructions, it does not break
 133    existing compilers/optimizers.
 134  */
 135 #define SKF_AD_OFF    (-0x1000)
 136 #define SKF_AD_PROTOCOL 0
 137 #define SKF_AD_PKTTYPE  4
 138 #define SKF_AD_IFINDEX  8
 139 #define SKF_AD_MAX      12
 140 #define SKF_NET_OFF   (-0x100000)
 141 #define SKF_LL_OFF    (-0x200000)
 142
 143 #ifdef __KERNEL__
 144 struct sk_buff;
 145 struct sock;
 146
 147 extern unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen);
 148 extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 149 extern int sk_detach_filter(struct sock *sk);
 150 extern int sk_chk_filter(struct sock_filter *filter, int flen);
 151 #endif /* __KERNEL__ */
 152
 153 #endif /* __LINUX_FILTER_H__ */