[NET]: Consolidate common code in net/core/filter.c

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/filter.c

@@ -36,7 +36,7 @@
 #include <linux/filter.h>
 
 /* No hurry in this branch */
-static u8 *load_pointer(struct sk_buff *skb, int k)
+static void *__load_pointer(struct sk_buff *skb, int k)
 {
 	u8 *ptr = NULL;
 
@@ -50,6 +50,18 @@ static u8 *load_pointer(struct sk_buff *skb, int k)
 	return NULL;
 }
 
+static inline void *load_pointer(struct sk_buff *skb, int k,
+                                 unsigned int size, void *buffer)
+{
+	if (k >= 0)
+		return skb_header_pointer(skb, k, size, buffer);
+	else {
+		if (k >= SKF_AD_OFF)
+			return NULL;
+		return __load_pointer(skb, k);
+	}
+}
+
 /**
  *	sk_run_filter	- 	run a filter on a socket
  *	@skb: buffer to run the filter on
@@ -64,15 +76,16 @@ static u8 *load_pointer(struct sk_buff *skb, int k)
  
 int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen)
 {
-	unsigned char *data = skb->data;
 	/* len is UNSIGNED. Byte wide insns relies only on implicit
 	   type casts to prevent reading arbitrary memory locations.
 	 */
 	unsigned int len = skb->len-skb->data_len;
 	struct sock_filter *fentry;	/* We walk down these */
+	void *ptr;
 	u32 A = 0;	   		/* Accumulator */
 	u32 X = 0;   			/* Index Register */
 	u32 mem[BPF_MEMWORDS];		/* Scratch Memory Store */
+	u32 tmp;
 	int k;
 	int pc;
 
@@ -168,68 +181,29 @@ int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen)
 		case BPF_LD|BPF_W|BPF_ABS:
 			k = fentry->k;
  load_w:
-			if (k < 0) {
-				u8 *ptr;
-
-				if (k >= SKF_AD_OFF)
-					break;
-				ptr = load_pointer(skb, k);
-				if (ptr) {
-					A = ntohl(*(u32*)ptr);
-					continue;
-				}
-			} else {
-				u32 _tmp, *p;
-				p = skb_header_pointer(skb, k, 4, &_tmp);
-				if (p != NULL) {
-					A = ntohl(*p);
+			ptr = load_pointer(skb, k, 4, &tmp);
+			if (ptr != NULL) {
+				A = ntohl(*(u32 *)ptr);
 				continue;
 			}
-			}
 			return 0;
 		case BPF_LD|BPF_H|BPF_ABS:
 			k = fentry->k;
  load_h:
-			if (k < 0) {
-				u8 *ptr;
-
-				if (k >= SKF_AD_OFF)
-					break;
-				ptr = load_pointer(skb, k);
-				if (ptr) {
-					A = ntohs(*(u16*)ptr);
+			ptr = load_pointer(skb, k, 2, &tmp);
+			if (ptr != NULL) {
+				A = ntohs(*(u16 *)ptr);
 				continue;
 			}
-			} else {
-				u16 _tmp, *p;
-				p = skb_header_pointer(skb, k, 2, &_tmp);
-				if (p != NULL) {
-					A = ntohs(*p);
-					continue;
-				}
-			}
 			return 0;
 		case BPF_LD|BPF_B|BPF_ABS:
 			k = fentry->k;
 load_b:
-			if (k < 0) {
-				u8 *ptr;
-
-				if (k >= SKF_AD_OFF)
-					break;
-				ptr = load_pointer(skb, k);
-				if (ptr) {
-					A = *ptr;
+			ptr = load_pointer(skb, k, 1, &tmp);
+			if (ptr != NULL) {
+				A = *(u8 *)ptr;
 				continue;
 			}
-			} else {
-				u8 _tmp, *p;
-				p = skb_header_pointer(skb, k, 1, &_tmp);
-				if (p != NULL) {
-					A = *p;
-					continue;
-				}
-			}
 			return 0;
 		case BPF_LD|BPF_W|BPF_LEN:
 			A = len;
@@ -247,10 +221,12 @@ int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen)
 			k = X + fentry->k;
 			goto load_b;
 		case BPF_LDX|BPF_B|BPF_MSH:
-			if (fentry->k >= len)
-				return 0;
-			X = (data[fentry->k] & 0xf) << 2;
+			ptr = load_pointer(skb, fentry->k, 1, &tmp);
+			if (ptr != NULL) {
+				X = (*(u8 *)ptr & 0xf) << 2;
 				continue;
+			}
+			return 0;
 		case BPF_LD|BPF_IMM:
 			A = fentry->k;
 			continue;