ipv6: Use ipv6_authlen for len

The length of AH header is computed manually as (hp->hdrlen+2)<<2.
However, in include/linux/ipv6.h, a macro named ipv6_authlen is
already defined for exactly the same job. This commit replaces
the manual computation code with the macro.
Signed-off-by: Nyangxingwu <xingwu.yang@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/ah6.c

@@ -464,7 +464,7 @@ static void ah6_input_done(struct crypto_async_request *base, int err)
 	struct ah_data *ahp = x->data;
 	struct ip_auth_hdr *ah = ip_auth_hdr(skb);
 	int hdr_len = skb_network_header_len(skb);
-	int ah_hlen = (ah->hdrlen + 2) << 2;
+	int ah_hlen = ipv6_authlen(ah);
 
 	if (err)
 		goto out;
@@ -546,7 +546,7 @@ static int ah6_input(struct xfrm_state *x, struct sk_buff *skb)
 	ahash = ahp->ahash;
 
 	nexthdr = ah->nexthdr;
-	ah_hlen = (ah->hdrlen + 2) << 2;
+	ah_hlen = ipv6_authlen(ah);
 
 	if (ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_full_len) &&
 	    ah_hlen != XFRM_ALIGN8(sizeof(*ah) + ahp->icv_trunc_len))

net/ipv6/exthdrs_core.c

@@ -266,7 +266,7 @@ int ipv6_find_hdr(const struct sk_buff *skb, unsigned int *offset,
 		} else if (nexthdr == NEXTHDR_AUTH) {
 			if (flags && (*flags & IP6_FH_F_AUTH) && (target < 0))
 				break;
-			hdrlen = (hp->hdrlen + 2) << 2;
+			hdrlen = ipv6_authlen(hp);
 		} else
 			hdrlen = ipv6_optlen(hp);
 

net/ipv6/ip6_tunnel.c

@@ -416,7 +416,7 @@ __u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw)
 				break;
 			optlen = 8;
 		} else if (nexthdr == NEXTHDR_AUTH) {
-			optlen = (hdr->hdrlen + 2) << 2;
+			optlen = ipv6_authlen(hdr);
 		} else {
 			optlen = ipv6_optlen(hdr);
 		}

net/ipv6/netfilter/ip6t_ah.c

@@ -55,7 +55,7 @@ static bool ah_mt6(const struct sk_buff *skb, struct xt_action_param *par)
 		return false;
 	}
 
-	hdrlen = (ah->hdrlen + 2) << 2;
+	hdrlen = ipv6_authlen(ah);
 
 	pr_debug("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
 	pr_debug("RES %04X ", ah->reserved);

net/ipv6/netfilter/ip6t_ipv6header.c

@@ -71,7 +71,7 @@ ipv6header_mt6(const struct sk_buff *skb, struct xt_action_param *par)
 		if (nexthdr == NEXTHDR_FRAGMENT)
 			hdrlen = 8;
 		else if (nexthdr == NEXTHDR_AUTH)
-			hdrlen = (hp->hdrlen + 2) << 2;
+			hdrlen = ipv6_authlen(hp);
 		else
 			hdrlen = ipv6_optlen(hp);
 

net/ipv6/netfilter/nf_conntrack_reasm.c

@@ -414,7 +414,7 @@ find_prev_fhdr(struct sk_buff *skb, u8 *prevhdrp, int *prevhoff, int *fhoff)
 		if (skb_copy_bits(skb, start, &hdr, sizeof(hdr)))
 			BUG();
 		if (nexthdr == NEXTHDR_AUTH)
-			hdrlen = (hdr.hdrlen+2)<<2;
+			hdrlen = ipv6_authlen(&hdr);
 		else
 			hdrlen = ipv6_optlen(&hdr);
 

net/ipv6/netfilter/nf_log_ipv6.c

@@ -155,7 +155,7 @@ static void dump_ipv6_packet(struct net *net, struct nf_log_buf *m,
 
 			}
 
-			hdrlen = (hp->hdrlen+2)<<2;
+			hdrlen = ipv6_authlen(hp);
 			break;
 		case IPPROTO_ESP:
 			if (logflags & NF_LOG_IPOPT) {