LXR linux/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 
  26struct sock_filter {    /* Filter block */
  27        __u16   code;   /* Actual filter code */
  28        __u8    jt;     /* Jump true */
  29        __u8    jf;     /* Jump false */
  30        __u32   k;      /* Generic multiuse field */
  31};
  32
  33struct sock_fprog {     /* Required for SO_ATTACH_FILTER. */
  34        unsigned short          len;    /* Number of filter blocks */
  35        struct sock_filter __user *filter;
  36};
  37
  38/*
  39 * Instruction classes
  40 */
  41
  42#define BPF_CLASS(code) ((code) & 0x07)
  43#define         BPF_LD          0x00
  44#define         BPF_LDX         0x01
  45#define         BPF_ST          0x02
  46#define         BPF_STX         0x03
  47#define         BPF_ALU         0x04
  48#define         BPF_JMP         0x05
  49#define         BPF_RET         0x06
  50#define         BPF_MISC        0x07
  51
  52/* ld/ldx fields */
  53#define BPF_SIZE(code)  ((code) & 0x18)
  54#define         BPF_W           0x00
  55#define         BPF_H           0x08
  56#define         BPF_B           0x10
  57#define BPF_MODE(code)  ((code) & 0xe0)
  58#define         BPF_IMM         0x00
  59#define         BPF_ABS         0x20
  60#define         BPF_IND         0x40
  61#define         BPF_MEM         0x60
  62#define         BPF_LEN         0x80
  63#define         BPF_MSH         0xa0
  64
  65/* alu/jmp fields */
  66#define BPF_OP(code)    ((code) & 0xf0)
  67#define         BPF_ADD         0x00
  68#define         BPF_SUB         0x10
  69#define         BPF_MUL         0x20
  70#define         BPF_DIV         0x30
  71#define         BPF_OR          0x40
  72#define         BPF_AND         0x50
  73#define         BPF_LSH         0x60
  74#define         BPF_RSH         0x70
  75#define         BPF_NEG         0x80
  76#define         BPF_JA          0x00
  77#define         BPF_JEQ         0x10
  78#define         BPF_JGT         0x20
  79#define         BPF_JGE         0x30
  80#define         BPF_JSET        0x40
  81#define BPF_SRC(code)   ((code) & 0x08)
  82#define         BPF_K           0x00
  83#define         BPF_X           0x08
  84
  85/* ret - BPF_K and BPF_X also apply */
  86#define BPF_RVAL(code)  ((code) & 0x18)
  87#define         BPF_A           0x10
  88
  89/* misc */
  90#define BPF_MISCOP(code) ((code) & 0xf8)
  91#define         BPF_TAX         0x00
  92#define         BPF_TXA         0x80
  93
  94#ifndef BPF_MAXINSNS
  95#define BPF_MAXINSNS 4096
  96#endif
  97
  98/*
  99 * Macros for filter block array initializers.
 100 */
 101#ifndef BPF_STMT
 102#define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
 103#endif
 104#ifndef BPF_JUMP
 105#define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
 106#endif
 107
 108/*
 109 * Number of scratch memory words for: BPF_ST and BPF_STX
 110 */
 111#define BPF_MEMWORDS 16
 112
 113/* RATIONALE. Negative offsets are invalid in BPF.
 114   We use them to reference ancillary data.
 115   Unlike introduction new instructions, it does not break
 116   existing compilers/optimizers.
 117 */
 118#define SKF_AD_OFF    (-0x1000)
 119#define SKF_AD_PROTOCOL 0
 120#define SKF_AD_PKTTYPE  4
 121#define SKF_AD_IFINDEX  8
 122#define SKF_AD_NLATTR   12
 123#define SKF_AD_NLATTR_NEST      16
 124#define SKF_AD_MARK     20
 125#define SKF_AD_QUEUE    24
 126#define SKF_AD_HATYPE   28
 127#define SKF_AD_RXHASH   32
 128#define SKF_AD_CPU      36
 129#define SKF_AD_MAX      40
 130#define SKF_NET_OFF   (-0x100000)
 131#define SKF_LL_OFF    (-0x200000)
 132
 133#ifdef __KERNEL__
 134struct sk_filter
 135{
 136        atomic_t                refcnt;
 137        unsigned int            len;    /* Number of filter blocks */
 138        struct rcu_head         rcu;
 139        struct sock_filter      insns[0];
 140};
 141
 142static inline unsigned int sk_filter_len(const struct sk_filter *fp)
 143{
 144        return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
 145}
 146
 147struct sk_buff;
 148struct sock;
 149
 150extern int sk_filter(struct sock *sk, struct sk_buff *skb);
 151extern unsigned int sk_run_filter(const struct sk_buff *skb,
 152                                  const struct sock_filter *filter);
 153extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 154extern int sk_detach_filter(struct sock *sk);
 155extern int sk_chk_filter(struct sock_filter *filter, int flen);
 156#endif /* __KERNEL__ */
 157
 158#endif /* __LINUX_FILTER_H__ */
 159