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 /*
  41  * Instruction classes
  42  */
  43
  44 #define BPF_CLASS(code) ((code) & 0x07)
  45 #define         BPF_LD          0x00
  46 #define         BPF_LDX         0x01
  47 #define         BPF_ST          0x02
  48 #define         BPF_STX         0x03
  49 #define         BPF_ALU         0x04
  50 #define         BPF_JMP         0x05
  51 #define         BPF_RET         0x06
  52 #define         BPF_MISC        0x07
  53
  54 /* ld/ldx fields */
  55 #define BPF_SIZE(code)  ((code) & 0x18)
  56 #define         BPF_W           0x00
  57 #define         BPF_H           0x08
  58 #define         BPF_B           0x10
  59 #define BPF_MODE(code)  ((code) & 0xe0)
  60 #define         BPF_IMM         0x00
  61 #define         BPF_ABS         0x20
  62 #define         BPF_IND         0x40
  63 #define         BPF_MEM         0x60
  64 #define         BPF_LEN         0x80
  65 #define         BPF_MSH         0xa0
  66
  67 /* alu/jmp fields */
  68 #define BPF_OP(code)    ((code) & 0xf0)
  69 #define         BPF_ADD         0x00
  70 #define         BPF_SUB         0x10
  71 #define         BPF_MUL         0x20
  72 #define         BPF_DIV         0x30
  73 #define         BPF_OR          0x40
  74 #define         BPF_AND         0x50
  75 #define         BPF_LSH         0x60
  76 #define         BPF_RSH         0x70
  77 #define         BPF_NEG         0x80
  78 #define         BPF_JA          0x00
  79 #define         BPF_JEQ         0x10
  80 #define         BPF_JGT         0x20
  81 #define         BPF_JGE         0x30
  82 #define         BPF_JSET        0x40
  83 #define BPF_SRC(code)   ((code) & 0x08)
  84 #define         BPF_K           0x00
  85 #define         BPF_X           0x08
  86
  87 /* ret - BPF_K and BPF_X also apply */
  88 #define BPF_RVAL(code)  ((code) & 0x18)
  89 #define         BPF_A           0x10
  90
  91 /* misc */
  92 #define BPF_MISCOP(code) ((code) & 0xf8)
  93 #define         BPF_TAX         0x00
  94 #define         BPF_TXA         0x80
  95
  96 #ifndef BPF_MAXINSNS
  97 #define BPF_MAXINSNS 4096
  98 #endif
  99
 100 /*
 101  * Macros for filter block array initializers.
 102  */
 103 #ifndef BPF_STMT
 104 #define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
 105 #endif
 106 #ifndef BPF_JUMP
 107 #define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
 108 #endif
 109
 110 /*
 111  * Number of scratch memory words for: BPF_ST and BPF_STX
 112  */
 113 #define BPF_MEMWORDS 16
 114
 115 /* RATIONALE. Negative offsets are invalid in BPF.
 116    We use them to reference ancillary data.
 117    Unlike introduction new instructions, it does not break
 118    existing compilers/optimizers.
 119  */
 120 #define SKF_AD_OFF    (-0x1000)
 121 #define SKF_AD_PROTOCOL 0
 122 #define SKF_AD_PKTTYPE  4
 123 #define SKF_AD_IFINDEX  8
 124 #define SKF_AD_NLATTR   12
 125 #define SKF_AD_NLATTR_NEST      16
 126 #define SKF_AD_MAX      20
 127 #define SKF_NET_OFF   (-0x100000)
 128 #define SKF_LL_OFF    (-0x200000)
 129
 130 #ifdef __KERNEL__
 131 struct sk_filter
 132 {
 133         atomic_t                refcnt;
 134         unsigned int            len;    /* Number of filter blocks */
 135         struct rcu_head         rcu;
 136         struct sock_filter      insns[0];
 137 };
 138
 139 static inline unsigned int sk_filter_len(const struct sk_filter *fp)
 140 {
 141         return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
 142 }
 143
 144 struct sk_buff;
 145 struct sock;
 146
 147 extern int sk_filter(struct sock *sk, struct sk_buff *skb);
 148 extern unsigned int sk_run_filter(struct sk_buff *skb,
 149                                   struct sock_filter *filter, int flen);
 150 extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 151 extern int sk_detach_filter(struct sock *sk);
 152 extern int sk_chk_filter(struct sock_filter *filter, int flen);
 153 #endif /* __KERNEL__ */
 154
 155 #endif /* __LINUX_FILTER_H__ */