--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/include/linux/filter.h	Sun Jan 11 20:20:11 2009 +0100
@@ -0,0 +1,154 @@
+/*
+ * Linux Socket Filter Data Structures
+ */
+
+#ifndef __LINUX_FILTER_H__
+#define __LINUX_FILTER_H__
+
+#include <linux/compiler.h>
+#include <linux/types.h>
+
+#ifdef __KERNEL__
+#include <asm/atomic.h>
+#endif
+
+/*
+ * Current version of the filter code architecture.
+ */
+#define BPF_MAJOR_VERSION 1
+#define BPF_MINOR_VERSION 1
+
+/*
+ *	Try and keep these values and structures similar to BSD, especially
+ *	the BPF code definitions which need to match so you can share filters
+ */
+ 
+struct sock_filter	/* Filter block */
+{
+	__u16	code;   /* Actual filter code */
+	__u8	jt;	/* Jump true */
+	__u8	jf;	/* Jump false */
+	__u32	k;      /* Generic multiuse field */
+};
+
+struct sock_fprog	/* Required for SO_ATTACH_FILTER. */
+{
+	unsigned short		len;	/* Number of filter blocks */
+	struct sock_filter __user *filter;
+};
+
+/*
+ * Instruction classes
+ */
+
+#define BPF_CLASS(code) ((code) & 0x07)
+#define         BPF_LD          0x00
+#define         BPF_LDX         0x01
+#define         BPF_ST          0x02
+#define         BPF_STX         0x03
+#define         BPF_ALU         0x04
+#define         BPF_JMP         0x05
+#define         BPF_RET         0x06
+#define         BPF_MISC        0x07
+
+/* ld/ldx fields */
+#define BPF_SIZE(code)  ((code) & 0x18)
+#define         BPF_W           0x00
+#define         BPF_H           0x08
+#define         BPF_B           0x10
+#define BPF_MODE(code)  ((code) & 0xe0)
+#define         BPF_IMM         0x00
+#define         BPF_ABS         0x20
+#define         BPF_IND         0x40
+#define         BPF_MEM         0x60
+#define         BPF_LEN         0x80
+#define         BPF_MSH         0xa0
+
+/* alu/jmp fields */
+#define BPF_OP(code)    ((code) & 0xf0)
+#define         BPF_ADD         0x00
+#define         BPF_SUB         0x10
+#define         BPF_MUL         0x20
+#define         BPF_DIV         0x30
+#define         BPF_OR          0x40
+#define         BPF_AND         0x50
+#define         BPF_LSH         0x60
+#define         BPF_RSH         0x70
+#define         BPF_NEG         0x80
+#define         BPF_JA          0x00
+#define         BPF_JEQ         0x10
+#define         BPF_JGT         0x20
+#define         BPF_JGE         0x30
+#define         BPF_JSET        0x40
+#define BPF_SRC(code)   ((code) & 0x08)
+#define         BPF_K           0x00
+#define         BPF_X           0x08
+
+/* ret - BPF_K and BPF_X also apply */
+#define BPF_RVAL(code)  ((code) & 0x18)
+#define         BPF_A           0x10
+
+/* misc */
+#define BPF_MISCOP(code) ((code) & 0xf8)
+#define         BPF_TAX         0x00
+#define         BPF_TXA         0x80
+
+#ifndef BPF_MAXINSNS
+#define BPF_MAXINSNS 4096
+#endif
+
+/*
+ * Macros for filter block array initializers.
+ */
+#ifndef BPF_STMT
+#define BPF_STMT(code, k) { (unsigned short)(code), 0, 0, k }
+#endif
+#ifndef BPF_JUMP
+#define BPF_JUMP(code, k, jt, jf) { (unsigned short)(code), jt, jf, k }
+#endif
+
+/*
+ * Number of scratch memory words for: BPF_ST and BPF_STX
+ */
+#define BPF_MEMWORDS 16
+
+/* RATIONALE. Negative offsets are invalid in BPF.
+   We use them to reference ancillary data.
+   Unlike introduction new instructions, it does not break
+   existing compilers/optimizers.
+ */
+#define SKF_AD_OFF    (-0x1000)
+#define SKF_AD_PROTOCOL 0
+#define SKF_AD_PKTTYPE 	4
+#define SKF_AD_IFINDEX 	8
+#define SKF_AD_NLATTR	12
+#define SKF_AD_MAX 	16
+#define SKF_NET_OFF   (-0x100000)
+#define SKF_LL_OFF    (-0x200000)
+
+#ifdef __KERNEL__
+struct sk_filter
+{
+	atomic_t		refcnt;
+	unsigned int         	len;	/* Number of filter blocks */
+	struct rcu_head		rcu;
+	struct sock_filter     	insns[0];
+};
+
+static inline unsigned int sk_filter_len(const struct sk_filter *fp)
+{
+	return fp->len * sizeof(struct sock_filter) + sizeof(*fp);
+}
+
+struct sk_buff;
+struct sock;
+
+extern int sk_filter(struct sock *sk, struct sk_buff *skb);
+extern unsigned int sk_run_filter(struct sk_buff *skb,
+				  struct sock_filter *filter, int flen);
+extern int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
+extern int sk_detach_filter(struct sock *sk);
+extern int sk_chk_filter(struct sock_filter *filter, int flen);
+#endif /* __KERNEL__ */
+
+#endif /* __LINUX_FILTER_H__ */