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