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         __u16   code;   /* Actual filter code */
  28         __u8    jt;     /* Jump true */
  29         __u8    jf;     /* Jump false */
  30         __u32   k;      /* Generic multiuse field */
  31 };
  32
  33 struct 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 enum {
  95         BPF_S_RET_K = 0,
  96         BPF_S_RET_A,
  97         BPF_S_ALU_ADD_K,
  98         BPF_S_ALU_ADD_X,
  99         BPF_S_ALU_SUB_K,
 100         BPF_S_ALU_SUB_X,
 101         BPF_S_ALU_MUL_K,
 102         BPF_S_ALU_MUL_X,
 103         BPF_S_ALU_DIV_X,
 104         BPF_S_ALU_AND_K,
 105         BPF_S_ALU_AND_X,
 106         BPF_S_ALU_OR_K,
 107         BPF_S_ALU_OR_X,
 108         BPF_S_ALU_LSH_K,
 109         BPF_S_ALU_LSH_X,
 110         BPF_S_ALU_RSH_K,
 111         BPF_S_ALU_RSH_X,
 112         BPF_S_ALU_NEG,
 113         BPF_S_LD_W_ABS,
 114         BPF_S_LD_H_ABS,
 115         BPF_S_LD_B_ABS,
 116         BPF_S_LD_W_LEN,
 117         BPF_S_LD_W_IND,
 118         BPF_S_LD_H_IND,
 119         BPF_S_LD_B_IND,
 120         BPF_S_LD_IMM,
 121         BPF_S_LDX_W_LEN,
 122         BPF_S_LDX_B_MSH,
 123         BPF_S_LDX_IMM,
 124         BPF_S_MISC_TAX,
 125         BPF_S_MISC_TXA,
 126         BPF_S_ALU_DIV_K,
 127         BPF_S_LD_MEM,
 128         BPF_S_LDX_MEM,
 129         BPF_S_ST,
 130         BPF_S_STX,
 131         BPF_S_JMP_JA,
 132         BPF_S_JMP_JEQ_K,
 133         BPF_S_JMP_JEQ_X,
 134         BPF_S_JMP_JGE_K,
 135         BPF_S_JMP_JGE_X,
 136         BPF_S_JMP_JGT_K,
 137         BPF_S_JMP_JGT_X,
 138         BPF_S_JMP_JSET_K,
 139         BPF_S_JMP_JSET_X,
 140 };
 141
 142 #ifndef BPF_MAXINSNS
 143 #define BPF_MAXINSNS 4096
 144 #endif
 145
 146 /*
 147  * Macros for filter block array initializers.
 148  */
 149 #ifndef BPF_STMT
 150 #define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
 151 #endif
 152 #ifndef BPF_JUMP
 153 #define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
 154 #endif
 155
 156 /*
 157  * Number of scratch memory words for: BPF_ST and BPF_STX
 158  */
 159 #define BPF_MEMWORDS 16
 160
 161 /* RATIONALE. Negative offsets are invalid in BPF.
 162    We use them to reference ancillary data.
 163    Unlike introduction new instructions, it does not break
 164    existing compilers/optimizers.
 165  */
 166 #define SKF_AD_OFF    (-0x1000)
 167 #define SKF_AD_PROTOCOL 0
 168 #define SKF_AD_PKTTYPE  4
 169 #define SKF_AD_IFINDEX  8
 170 #define SKF_AD_NLATTR   12
 171 #define SKF_AD_NLATTR_NEST      16
 172 #define SKF_AD_MARK     20
 173 #define SKF_AD_QUEUE    24
 174 #define SKF_AD_HATYPE   28
 175 #define SKF_AD_MAX      32
 176 #define SKF_NET_OFF   (-0x100000)
 177 #define SKF_LL_OFF    (-0x200000)
 178
 179 #ifdef __KERNEL__
 180 struct sk_filter
 181 {
 182         atomic_t                refcnt;
 183         unsigned int            len;    /* Number of filter blocks */
 184         struct rcu_head         rcu;
 185         struct sock_filter      insns[0];
 186 };
 187
 188 static inline unsigned int sk_filter_len(const struct sk_filter *fp)
 189 {
 190         return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
 191 }
 192
 193 struct sk_buff;
 194 struct sock;
 195
 196 extern int sk_filter(struct sock *sk, struct sk_buff *skb);
 197 extern unsigned int sk_run_filter(struct sk_buff *skb,
 198                                   struct sock_filter *filter, int flen);
 199 extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 200 extern int sk_detach_filter(struct sock *sk);
 201 extern int sk_chk_filter(struct sock_filter *filter, int flen);
 202 #endif /* __KERNEL__ */
 203
 204 #endif /* __LINUX_FILTER_H__ */