[IPSEC]: Use "sizeof" for header sizes.

net/ipv4/ah.c

@@ -18,7 +18,7 @@
 static int ip_clear_mutable_options(struct iphdr *iph, u32 *daddr)
 {
 	unsigned char * optptr = (unsigned char*)(iph+1);
-	int  l = iph->ihl*4 - 20;
+	int  l = iph->ihl*4 - sizeof(struct iphdr);
 	int  optlen;
 
 	while (l > 0) {
@@ -132,7 +132,7 @@ static int ah_output(struct sk_buff *skb)
 		top_iph->frag_off = iph->frag_off;
 		top_iph->daddr = iph->daddr;
 		if (iph->ihl != 5)
-			memcpy(top_iph+1, iph+1, iph->ihl*5 - 20);
+			memcpy(top_iph+1, iph+1, iph->ihl*4 - sizeof(struct iphdr));
 	}
 	ip_send_check(top_iph);
 
@@ -288,7 +288,7 @@ static int ah_init_state(struct xfrm_state *x, void *args)
 	
 	x->props.header_len = XFRM_ALIGN8(ahp->icv_trunc_len + AH_HLEN_NOICV);
 	if (x->props.mode)
-		x->props.header_len += 20;
+		x->props.header_len += sizeof(struct iphdr);
 	x->data = ahp;
 
 	return 0;

net/ipv4/esp.c

@@ -367,7 +367,7 @@ int esp_init_state(struct xfrm_state *x, void *args)
 	crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len);
 	x->props.header_len = 8 + esp->conf.ivlen;
 	if (x->props.mode)
-		x->props.header_len += 20;
+		x->props.header_len += sizeof(struct iphdr);
 	x->data = esp;
 	x->props.trailer_len = esp4_get_max_size(x, 0) - x->props.header_len;
 	return 0;

net/ipv6/ah6.c

@@ -287,7 +287,7 @@ static int ah6_init_state(struct xfrm_state *x, void *args)
 	
 	x->props.header_len = XFRM_ALIGN8(ahp->icv_trunc_len + AH_HLEN_NOICV);
 	if (x->props.mode)
-		x->props.header_len += 40;
+		x->props.header_len += sizeof(struct ipv6hdr);
 	x->data = ahp;
 
 	return 0;

net/ipv6/esp6.c

@@ -468,7 +468,7 @@ int esp6_init_state(struct xfrm_state *x, void *args)
 	crypto_cipher_setkey(esp->conf.tfm, esp->conf.key, esp->conf.key_len);
 	x->props.header_len = 8 + esp->conf.ivlen;
 	if (x->props.mode)
-		x->props.header_len += 40;  /* XXX ext hdr */
+		x->props.header_len += sizeof(struct ipv6hdr);
 	x->data = esp;
 	return 0;