[NET]: netfilter checksum annotations

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netfilter.h

@@ -282,11 +282,27 @@ extern void nf_invalidate_cache(int pf);
    Returns true or false. */
 extern int skb_make_writable(struct sk_buff **pskb, unsigned int writable_len);
 
-extern u_int16_t nf_csum_update(u_int32_t oldval, u_int32_t newval,
-				u_int32_t csum);
-extern u_int16_t nf_proto_csum_update(struct sk_buff *skb,
-				      u_int32_t oldval, u_int32_t newval,
-				      u_int16_t csum, int pseudohdr);
+static inline void nf_csum_replace4(__sum16 *sum, __be32 from, __be32 to)
+{
+	__be32 diff[] = { ~from, to };
+
+	*sum = csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum_unfold(*sum)));
+}
+
+static inline void nf_csum_replace2(__sum16 *sum, __be16 from, __be16 to)
+{
+	nf_csum_replace4(sum, (__force __be32)from, (__force __be32)to);
+}
+
+extern void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
+				      __be32 from, __be32 to, int pseudohdr);
+
+static inline void nf_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
+				      __be16 from, __be16 to, int pseudohdr)
+{
+	nf_proto_csum_replace4(sum, skb, (__force __be32)from,
+				(__force __be32)to, pseudohdr);
+}
 
 struct nf_afinfo {
 	unsigned short	family;

include/linux/netfilter_ipv4/ip_conntrack_proto_gre.h

@@ -102,11 +102,11 @@ static inline __be32 *gre_key(struct gre_hdr *greh)
 }
 
 /* get pointer ot gre csum, if present */
-static inline u_int16_t *gre_csum(struct gre_hdr *greh)
+static inline __sum16 *gre_csum(struct gre_hdr *greh)
 {
 	if (!greh->csum)
 		return NULL;
-	return (u_int16_t *) (greh+sizeof(*greh));
+	return (__sum16 *) (greh+sizeof(*greh));
 }
 
 #endif /* __KERNEL__ */

net/ipv4/netfilter/ip_nat_core.c

@@ -362,12 +362,10 @@ manip_pkt(u_int16_t proto,
 	iph = (void *)(*pskb)->data + iphdroff;
 
 	if (maniptype == IP_NAT_MANIP_SRC) {
-		iph->check = nf_csum_update(~iph->saddr, target->src.ip,
-					    iph->check);
+		nf_csum_replace4(&iph->check, iph->saddr, target->src.ip);
 		iph->saddr = target->src.ip;
 	} else {
-		iph->check = nf_csum_update(~iph->daddr, target->dst.ip,
-					    iph->check);
+		nf_csum_replace4(&iph->check, iph->daddr, target->dst.ip);
 		iph->daddr = target->dst.ip;
 	}
 	return 1;

net/ipv4/netfilter/ip_nat_helper.c

@@ -188,10 +188,8 @@ ip_nat_mangle_tcp_packet(struct sk_buff **pskb,
 					   csum_partial((char *)tcph,
 					   		datalen, 0));
 	} else
-		tcph->check = nf_proto_csum_update(*pskb,
-						   htons(oldlen) ^ htons(0xFFFF),
-						   htons(datalen),
-						   tcph->check, 1);
+		nf_proto_csum_replace2(&tcph->check, *pskb,
+					htons(oldlen), htons(datalen), 1);
 
 	if (rep_len != match_len) {
 		set_bit(IPS_SEQ_ADJUST_BIT, &ct->status);
@@ -266,10 +264,8 @@ ip_nat_mangle_udp_packet(struct sk_buff **pskb,
 		if (!udph->check)
 			udph->check = CSUM_MANGLED_0;
 	} else
-		udph->check = nf_proto_csum_update(*pskb,
-						   htons(oldlen) ^ htons(0xFFFF),
-						   htons(datalen),
-						   udph->check, 1);
+		nf_proto_csum_replace2(&udph->check, *pskb,
+					htons(oldlen), htons(datalen), 1);
 	return 1;
 }
 EXPORT_SYMBOL(ip_nat_mangle_udp_packet);
@@ -307,14 +303,10 @@ sack_adjust(struct sk_buff *skb,
 			ntohl(sack->start_seq), new_start_seq,
 			ntohl(sack->end_seq), new_end_seq);
 
-		tcph->check = nf_proto_csum_update(skb,
-						   ~sack->start_seq,
-						   new_start_seq,
-						   tcph->check, 0);
-		tcph->check = nf_proto_csum_update(skb,
-						   ~sack->end_seq,
-						   new_end_seq,
-						   tcph->check, 0);
+		nf_proto_csum_replace4(&tcph->check, skb,
+					sack->start_seq, new_start_seq, 0);
+		nf_proto_csum_replace4(&tcph->check, skb,
+					sack->end_seq, new_end_seq, 0);
 		sack->start_seq = new_start_seq;
 		sack->end_seq = new_end_seq;
 		sackoff += sizeof(*sack);
@@ -397,10 +389,8 @@ ip_nat_seq_adjust(struct sk_buff **pskb,
 	else
 		newack = htonl(ntohl(tcph->ack_seq) - other_way->offset_before);
 
-	tcph->check = nf_proto_csum_update(*pskb, ~tcph->seq, newseq,
-					   tcph->check, 0);
-	tcph->check = nf_proto_csum_update(*pskb, ~tcph->ack_seq, newack,
-					   tcph->check, 0);
+	nf_proto_csum_replace4(&tcph->check, *pskb, tcph->seq, newseq, 0);
+	nf_proto_csum_replace4(&tcph->check, *pskb, tcph->ack_seq, newack, 0);
 
 	DEBUGP("Adjusting sequence number from %u->%u, ack from %u->%u\n",
 		ntohl(tcph->seq), ntohl(newseq), ntohl(tcph->ack_seq),

net/ipv4/netfilter/ip_nat_proto_gre.c

@@ -129,11 +129,9 @@ gre_manip_pkt(struct sk_buff **pskb,
 			}
 			if (greh->csum) {
 				/* FIXME: Never tested this code... */
-				*(gre_csum(greh)) =
-					nf_proto_csum_update(*pskb,
-							~*(gre_key(greh)),
-							tuple->dst.u.gre.key,
-							*(gre_csum(greh)), 0);
+				nf_proto_csum_replace4(gre_csum(greh), *pskb,
+							*(gre_key(greh)),
+							tuple->dst.u.gre.key, 0);
 			}
 			*(gre_key(greh)) = tuple->dst.u.gre.key;
 			break;

net/ipv4/netfilter/ip_nat_proto_icmp.c

@@ -66,10 +66,8 @@ icmp_manip_pkt(struct sk_buff **pskb,
 		return 0;
 
 	hdr = (struct icmphdr *)((*pskb)->data + hdroff);
-	hdr->checksum = nf_proto_csum_update(*pskb,
-					     hdr->un.echo.id ^ htons(0xFFFF),
-					     tuple->src.u.icmp.id,
-					     hdr->checksum, 0);
+	nf_proto_csum_replace2(&hdr->checksum, *pskb,
+			       hdr->un.echo.id, tuple->src.u.icmp.id, 0);
 	hdr->un.echo.id = tuple->src.u.icmp.id;
 	return 1;
 }

net/ipv4/netfilter/ip_nat_proto_tcp.c

@@ -129,9 +129,8 @@ tcp_manip_pkt(struct sk_buff **pskb,
 	if (hdrsize < sizeof(*hdr))
 		return 1;
 
-	hdr->check = nf_proto_csum_update(*pskb, ~oldip, newip, hdr->check, 1);
-	hdr->check = nf_proto_csum_update(*pskb, oldport ^ htons(0xFFFF), newport,
-					  hdr->check, 0);
+	nf_proto_csum_replace4(&hdr->check, *pskb, oldip, newip, 1);
+	nf_proto_csum_replace2(&hdr->check, *pskb, oldport, newport, 0);
 	return 1;
 }
 

net/ipv4/netfilter/ip_nat_proto_udp.c

@@ -115,11 +115,8 @@ udp_manip_pkt(struct sk_buff **pskb,
 	}
 
 	if (hdr->check || (*pskb)->ip_summed == CHECKSUM_PARTIAL) {
-		hdr->check = nf_proto_csum_update(*pskb, ~oldip, newip,
-						  hdr->check, 1);
-		hdr->check = nf_proto_csum_update(*pskb,
-						  *portptr ^ htons(0xFFFF), newport,
-						  hdr->check, 0);
+		nf_proto_csum_replace4(&hdr->check, *pskb, oldip, newip, 1);
+		nf_proto_csum_replace2(&hdr->check, *pskb, *portptr, newport, 0);
 		if (!hdr->check)
 			hdr->check = CSUM_MANGLED_0;
 	}

net/ipv4/netfilter/ipt_ECN.c

@@ -28,17 +28,16 @@ static inline int
 set_ect_ip(struct sk_buff **pskb, const struct ipt_ECN_info *einfo)
 {
 	struct iphdr *iph = (*pskb)->nh.iph;
-	u_int16_t oldtos;
 
 	if ((iph->tos & IPT_ECN_IP_MASK) != (einfo->ip_ect & IPT_ECN_IP_MASK)) {
+		__u8 oldtos;
 		if (!skb_make_writable(pskb, sizeof(struct iphdr)))
 			return 0;
 		iph = (*pskb)->nh.iph;
 		oldtos = iph->tos;
 		iph->tos &= ~IPT_ECN_IP_MASK;
 		iph->tos |= (einfo->ip_ect & IPT_ECN_IP_MASK);
-		iph->check = nf_csum_update(htons(oldtos) ^ htons(0xFFFF),
-					    htons(iph->tos), iph->check);
+		nf_csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
 	} 
 	return 1;
 }
@@ -72,10 +71,8 @@ set_ect_tcp(struct sk_buff **pskb, const struct ipt_ECN_info *einfo)
 	if (einfo->operation & IPT_ECN_OP_SET_CWR)
 		tcph->cwr = einfo->proto.tcp.cwr;
 
-	tcph->check = nf_proto_csum_update((*pskb),
-					   oldval ^ htons(0xFFFF),
-					   ((__be16 *)tcph)[6],
-					   tcph->check, 0);
+	nf_proto_csum_replace2(&tcph->check, *pskb,
+				oldval, ((__be16 *)tcph)[6], 0);
 	return 1;
 }
 

net/ipv4/netfilter/ipt_TCPMSS.c

@@ -97,10 +97,8 @@ ipt_tcpmss_target(struct sk_buff **pskb,
 			opt[i+2] = (newmss & 0xff00) >> 8;
 			opt[i+3] = (newmss & 0x00ff);
 
-			tcph->check = nf_proto_csum_update(*pskb,
-							   htons(oldmss)^htons(0xFFFF),
-							   htons(newmss),
-							   tcph->check, 0);
+			nf_proto_csum_replace2(&tcph->check, *pskb,
+						htons(oldmss), htons(newmss), 0);
 			return IPT_CONTINUE;
 		}
 	}
@@ -126,28 +124,22 @@ ipt_tcpmss_target(struct sk_buff **pskb,
  	opt = (u_int8_t *)tcph + sizeof(struct tcphdr);
 	memmove(opt + TCPOLEN_MSS, opt, tcplen - sizeof(struct tcphdr));
 
-	tcph->check = nf_proto_csum_update(*pskb,
-					   htons(tcplen) ^ htons(0xFFFF),
-				           htons(tcplen + TCPOLEN_MSS),
-					   tcph->check, 1);
+	nf_proto_csum_replace2(&tcph->check, *pskb,
+				htons(tcplen), htons(tcplen + TCPOLEN_MSS), 1);
 	opt[0] = TCPOPT_MSS;
 	opt[1] = TCPOLEN_MSS;
 	opt[2] = (newmss & 0xff00) >> 8;
 	opt[3] = (newmss & 0x00ff);
 
-	tcph->check = nf_proto_csum_update(*pskb, htonl(~0), *((__be32 *)opt),
-					   tcph->check, 0);
+	nf_proto_csum_replace4(&tcph->check, *pskb, 0, *((__be32 *)opt), 0);
 
 	oldval = ((__be16 *)tcph)[6];
 	tcph->doff += TCPOLEN_MSS/4;
-	tcph->check = nf_proto_csum_update(*pskb,
-					   oldval ^ htons(0xFFFF),
-					   ((__be16 *)tcph)[6],
-					   tcph->check, 0);
+	nf_proto_csum_replace2(&tcph->check, *pskb,
+				oldval, ((__be16 *)tcph)[6], 0);
 
 	newtotlen = htons(ntohs(iph->tot_len) + TCPOLEN_MSS);
-	iph->check = nf_csum_update(iph->tot_len ^ htons(0xFFFF),
-				    newtotlen, iph->check);
+	nf_csum_replace2(&iph->check, iph->tot_len, newtotlen);
 	iph->tot_len = newtotlen;
 	return IPT_CONTINUE;
 }

net/ipv4/netfilter/ipt_TOS.c

@@ -30,16 +30,15 @@ target(struct sk_buff **pskb,
 {
 	const struct ipt_tos_target_info *tosinfo = targinfo;
 	struct iphdr *iph = (*pskb)->nh.iph;
-	u_int16_t oldtos;
 
 	if ((iph->tos & IPTOS_TOS_MASK) != tosinfo->tos) {
+		__u8 oldtos;
 		if (!skb_make_writable(pskb, sizeof(struct iphdr)))
 			return NF_DROP;
 		iph = (*pskb)->nh.iph;
 		oldtos = iph->tos;
 		iph->tos = (iph->tos & IPTOS_PREC_MASK) | tosinfo->tos;
-		iph->check = nf_csum_update(htons(oldtos) ^ htons(0xFFFF),
-					    htons(iph->tos), iph->check);
+		nf_csum_replace2(&iph->check, htons(oldtos), htons(iph->tos));
 	}
 	return IPT_CONTINUE;
 }

net/ipv4/netfilter/ipt_TTL.c

@@ -54,9 +54,8 @@ ipt_ttl_target(struct sk_buff **pskb,
 	}
 
 	if (new_ttl != iph->ttl) {
-		iph->check = nf_csum_update(htons((iph->ttl << 8)) ^ htons(0xFFFF),
-					    htons(new_ttl << 8),
-					    iph->check);
+		nf_csum_replace2(&iph->check, htons(iph->ttl << 8),
+					      htons(new_ttl << 8));
 		iph->ttl = new_ttl;
 	}
 

net/netfilter/core.c

@@ -222,28 +222,21 @@ copy_skb:
 }
 EXPORT_SYMBOL(skb_make_writable);
 
-u_int16_t nf_csum_update(u_int32_t oldval, u_int32_t newval, u_int32_t csum)
-{
-	u_int32_t diff[] = { oldval, newval };
-
-	return csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum));
-}
-EXPORT_SYMBOL(nf_csum_update);
-
-u_int16_t nf_proto_csum_update(struct sk_buff *skb,
-			       u_int32_t oldval, u_int32_t newval,
-			       u_int16_t csum, int pseudohdr)
+void nf_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
+			    __be32 from, __be32 to, int pseudohdr)
 {
+	__be32 diff[] = { ~from, to };
 	if (skb->ip_summed != CHECKSUM_PARTIAL) {
-		csum = nf_csum_update(oldval, newval, csum);
+		*sum = csum_fold(csum_partial((char *)diff, sizeof(diff),
+				~csum_unfold(*sum)));
 		if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr)
-			skb->csum = nf_csum_update(oldval, newval, skb->csum);
+			skb->csum = ~csum_partial((char *)diff, sizeof(diff),
+						~skb->csum);
 	} else if (pseudohdr)
-		csum = ~nf_csum_update(oldval, newval, ~csum);
-
-	return csum;
+		*sum = ~csum_fold(csum_partial((char *)diff, sizeof(diff),
+				csum_unfold(*sum)));
 }
-EXPORT_SYMBOL(nf_proto_csum_update);
+EXPORT_SYMBOL(nf_proto_csum_replace4);
 
 /* This does not belong here, but locally generated errors need it if connection
    tracking in use: without this, connection may not be in hash table, and hence