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
sk_filter_len(const struct sk_filter * fp)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__ */
156