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 <linux/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 #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__
134 
135 struct sk_buff;
136 struct sock;
137 
138 struct sk_filter
139 {
140 	atomic_t		refcnt;
141 	unsigned int         	len;	/* Number of filter blocks */
142 	unsigned int		(*bpf_func)(const struct sk_buff *skb,
143 					    const struct sock_filter *filter);
144 	struct rcu_head		rcu;
145 	struct sock_filter     	insns[0];
146 };
147 
sk_filter_len(const struct sk_filter * fp)148 static inline unsigned int sk_filter_len(const struct sk_filter *fp)
149 {
150 	return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
151 }
152 
153 extern int sk_filter(struct sock *sk, struct sk_buff *skb);
154 extern unsigned int sk_run_filter(const struct sk_buff *skb,
155 				  const struct sock_filter *filter);
156 extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
157 extern int sk_detach_filter(struct sock *sk);
158 extern int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
159 
160 #ifdef CONFIG_BPF_JIT
161 extern void bpf_jit_compile(struct sk_filter *fp);
162 extern void bpf_jit_free(struct sk_filter *fp);
163 #define SK_RUN_FILTER(FILTER, SKB) (*FILTER->bpf_func)(SKB, FILTER->insns)
164 #else
bpf_jit_compile(struct sk_filter * fp)165 static inline void bpf_jit_compile(struct sk_filter *fp)
166 {
167 }
bpf_jit_free(struct sk_filter * fp)168 static inline void bpf_jit_free(struct sk_filter *fp)
169 {
170 }
171 #define SK_RUN_FILTER(FILTER, SKB) sk_run_filter(SKB, FILTER->insns)
172 #endif
173 
174 enum {
175 	BPF_S_RET_K = 1,
176 	BPF_S_RET_A,
177 	BPF_S_ALU_ADD_K,
178 	BPF_S_ALU_ADD_X,
179 	BPF_S_ALU_SUB_K,
180 	BPF_S_ALU_SUB_X,
181 	BPF_S_ALU_MUL_K,
182 	BPF_S_ALU_MUL_X,
183 	BPF_S_ALU_DIV_X,
184 	BPF_S_ALU_AND_K,
185 	BPF_S_ALU_AND_X,
186 	BPF_S_ALU_OR_K,
187 	BPF_S_ALU_OR_X,
188 	BPF_S_ALU_LSH_K,
189 	BPF_S_ALU_LSH_X,
190 	BPF_S_ALU_RSH_K,
191 	BPF_S_ALU_RSH_X,
192 	BPF_S_ALU_NEG,
193 	BPF_S_LD_W_ABS,
194 	BPF_S_LD_H_ABS,
195 	BPF_S_LD_B_ABS,
196 	BPF_S_LD_W_LEN,
197 	BPF_S_LD_W_IND,
198 	BPF_S_LD_H_IND,
199 	BPF_S_LD_B_IND,
200 	BPF_S_LD_IMM,
201 	BPF_S_LDX_W_LEN,
202 	BPF_S_LDX_B_MSH,
203 	BPF_S_LDX_IMM,
204 	BPF_S_MISC_TAX,
205 	BPF_S_MISC_TXA,
206 	BPF_S_ALU_DIV_K,
207 	BPF_S_LD_MEM,
208 	BPF_S_LDX_MEM,
209 	BPF_S_ST,
210 	BPF_S_STX,
211 	BPF_S_JMP_JA,
212 	BPF_S_JMP_JEQ_K,
213 	BPF_S_JMP_JEQ_X,
214 	BPF_S_JMP_JGE_K,
215 	BPF_S_JMP_JGE_X,
216 	BPF_S_JMP_JGT_K,
217 	BPF_S_JMP_JGT_X,
218 	BPF_S_JMP_JSET_K,
219 	BPF_S_JMP_JSET_X,
220 	/* Ancillary data */
221 	BPF_S_ANC_PROTOCOL,
222 	BPF_S_ANC_PKTTYPE,
223 	BPF_S_ANC_IFINDEX,
224 	BPF_S_ANC_NLATTR,
225 	BPF_S_ANC_NLATTR_NEST,
226 	BPF_S_ANC_MARK,
227 	BPF_S_ANC_QUEUE,
228 	BPF_S_ANC_HATYPE,
229 	BPF_S_ANC_RXHASH,
230 	BPF_S_ANC_CPU,
231 };
232 
233 #endif /* __KERNEL__ */
234 
235 #endif /* __LINUX_FILTER_H__ */
236