1 /*
2 * Linux Socket Filter Data Structures
3 */
4
5 #ifndef __LINUX_FILTER_H__
6 #define __LINUX_FILTER_H__
7
8 /*
9 * Current version of the filter code architecture.
10 */
11 #define BPF_MAJOR_VERSION 1
12 #define BPF_MINOR_VERSION 1
13
14 /*
15 * Try and keep these values and structures similar to BSD, especially
16 * the BPF code definitions which need to match so you can share filters
17 */
18
19 struct sock_filter /* Filter block */
20 {
21 __u16 code; /* Actual filter code */
22 __u8 jt; /* Jump true */
23 __u8 jf; /* Jump false */
24 __u32 k; /* Generic multiuse field */
25 };
26
27 struct sock_fprog /* Required for SO_ATTACH_FILTER. */
28 {
29 unsigned short len; /* Number of filter blocks */
30 struct sock_filter *filter;
31 };
32
33 #ifdef __KERNEL__
34 struct sk_filter
35 {
36 atomic_t refcnt;
37 unsigned int len; /* Number of filter blocks */
38 struct sock_filter insns[0];
39 };
40
41 static inline unsigned int sk_filter_len(struct sk_filter *fp)
42 {
43 return fp->len*sizeof(struct sock_filter) + sizeof(*fp);
44 }
45 #endif
46
47 /*
48 * Instruction classes
49 */
50
51 #define BPF_CLASS(code) ((code) & 0x07)
52 #define BPF_LD 0x00
53 #define BPF_LDX 0x01
54 #define BPF_ST 0x02
55 #define BPF_STX 0x03
56 #define BPF_ALU 0x04
57 #define BPF_JMP 0x05
58 #define BPF_RET 0x06
59 #define BPF_MISC 0x07
60
61 /* ld/ldx fields */
62 #define BPF_SIZE(code) ((code) & 0x18)
63 #define BPF_W 0x00
64 #define BPF_H 0x08
65 #define BPF_B 0x10
66 #define BPF_MODE(code) ((code) & 0xe0)
67 #define BPF_IMM 0x00
68 #define BPF_ABS 0x20
69 #define BPF_IND 0x40
70 #define BPF_MEM 0x60
71 #define BPF_LEN 0x80
72 #define BPF_MSH 0xa0
73
74 /* alu/jmp fields */
75 #define BPF_OP(code) ((code) & 0xf0)
76 #define BPF_ADD 0x00
77 #define BPF_SUB 0x10
78 #define BPF_MUL 0x20
79 #define BPF_DIV 0x30
80 #define BPF_OR 0x40
81 #define BPF_AND 0x50
82 #define BPF_LSH 0x60
83 #define BPF_RSH 0x70
84 #define BPF_NEG 0x80
85 #define BPF_JA 0x00
86 #define BPF_JEQ 0x10
87 #define BPF_JGT 0x20
88 #define BPF_JGE 0x30
89 #define BPF_JSET 0x40
90 #define BPF_SRC(code) ((code) & 0x08)
91 #define BPF_K 0x00
92 #define BPF_X 0x08
93
94 /* ret - BPF_K and BPF_X also apply */
95 #define BPF_RVAL(code) ((code) & 0x18)
96 #define BPF_A 0x10
97
98 /* misc */
99 #define BPF_MISCOP(code) ((code) & 0xf8)
100 #define BPF_TAX 0x00
101 #define BPF_TXA 0x80
102
103 #ifndef BPF_MAXINSNS
104 #define BPF_MAXINSNS 4096
105 #endif
106
107 /*
108 * Macros for filter block array initializers.
109 */
110 #ifndef BPF_STMT
111 #define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
112 #endif
113 #ifndef BPF_JUMP
114 #define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
115 #endif
116
117 /*
118 * Number of scratch memory words for: BPF_ST and BPF_STX
119 */
120 #define BPF_MEMWORDS 16
121
122 /* RATIONALE. Negative offsets are invalid in BPF.
123 We use them to reference ancillary data.
124 Unlike introduction new instructions, it does not break
125 existing compilers/optimizers.
126 */
127 #define SKF_AD_OFF (-0x1000)
128 #define SKF_AD_PROTOCOL 0
129 #define SKF_AD_PKTTYPE 4
130 #define SKF_AD_IFINDEX 8
131 #define SKF_AD_MAX 12
132 #define SKF_NET_OFF (-0x100000)
133 #define SKF_LL_OFF (-0x200000)
134
135 #ifdef __KERNEL__
136 extern int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen);
137 extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
138 #endif /* __KERNEL__ */
139
140 #endif /* __LINUX_FILTER_H__ */
141
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