From 38a7e5b365edce1fc0a972a05bbda0673ca63cad Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Mon, 30 Sep 2019 16:25:42 +0200 Subject: checksum: Fix UDP checksum calculation The level 4 protocol is part of the UDP and TCP calculations. nfq_checksum_tcpudp_ipv4() was using IPPROTO_TCP in this calculation, which gave the wrong answer for UDP. Based on patch from Alin Nastac, and patch description from Duncan Roe. Signed-off-by: Pablo Neira Ayuso --- src/extra/checksum.c | 9 +++++---- src/extra/tcp.c | 4 ++-- src/extra/udp.c | 4 ++-- src/internal.h | 5 +++-- 4 files changed, 12 insertions(+), 10 deletions(-) diff --git a/src/extra/checksum.c b/src/extra/checksum.c index f367f75..4d52a99 100644 --- a/src/extra/checksum.c +++ b/src/extra/checksum.c @@ -35,7 +35,7 @@ uint16_t nfq_checksum(uint32_t sum, uint16_t *buf, int size) return (uint16_t)(~sum); } -uint16_t nfq_checksum_tcpudp_ipv4(struct iphdr *iph) +uint16_t nfq_checksum_tcpudp_ipv4(struct iphdr *iph, uint16_t protonum) { uint32_t sum = 0; uint32_t iph_len = iph->ihl*4; @@ -46,13 +46,14 @@ uint16_t nfq_checksum_tcpudp_ipv4(struct iphdr *iph) sum += (iph->saddr) & 0xFFFF; sum += (iph->daddr >> 16) & 0xFFFF; sum += (iph->daddr) & 0xFFFF; - sum += htons(IPPROTO_TCP); + sum += htons(protonum); sum += htons(len); return nfq_checksum(sum, (uint16_t *)payload, len); } -uint16_t nfq_checksum_tcpudp_ipv6(struct ip6_hdr *ip6h, void *transport_hdr) +uint16_t nfq_checksum_tcpudp_ipv6(struct ip6_hdr *ip6h, void *transport_hdr, + uint16_t protonum) { uint32_t sum = 0; uint32_t hdr_len = (uint32_t *)transport_hdr - (uint32_t *)ip6h; @@ -68,7 +69,7 @@ uint16_t nfq_checksum_tcpudp_ipv6(struct ip6_hdr *ip6h, void *transport_hdr) sum += (ip6h->ip6_dst.s6_addr16[i] >> 16) & 0xFFFF; sum += (ip6h->ip6_dst.s6_addr16[i]) & 0xFFFF; } - sum += htons(IPPROTO_TCP); + sum += htons(protonum); sum += htons(ip6h->ip6_plen); return nfq_checksum(sum, (uint16_t *)payload, len); diff --git a/src/extra/tcp.c b/src/extra/tcp.c index d1cd79d..a66f392 100644 --- a/src/extra/tcp.c +++ b/src/extra/tcp.c @@ -96,7 +96,7 @@ nfq_tcp_compute_checksum_ipv4(struct tcphdr *tcph, struct iphdr *iph) { /* checksum field in header needs to be zero for calculation. */ tcph->check = 0; - tcph->check = nfq_checksum_tcpudp_ipv4(iph); + tcph->check = nfq_checksum_tcpudp_ipv4(iph, IPPROTO_TCP); } EXPORT_SYMBOL(nfq_tcp_compute_checksum_ipv4); @@ -110,7 +110,7 @@ nfq_tcp_compute_checksum_ipv6(struct tcphdr *tcph, struct ip6_hdr *ip6h) { /* checksum field in header needs to be zero for calculation. */ tcph->check = 0; - tcph->check = nfq_checksum_tcpudp_ipv6(ip6h, tcph); + tcph->check = nfq_checksum_tcpudp_ipv6(ip6h, tcph, IPPROTO_TCP); } EXPORT_SYMBOL(nfq_tcp_compute_checksum_ipv6); diff --git a/src/extra/udp.c b/src/extra/udp.c index 8c44a66..c48a179 100644 --- a/src/extra/udp.c +++ b/src/extra/udp.c @@ -96,7 +96,7 @@ nfq_udp_compute_checksum_ipv4(struct udphdr *udph, struct iphdr *iph) { /* checksum field in header needs to be zero for calculation. */ udph->check = 0; - udph->check = nfq_checksum_tcpudp_ipv4(iph); + udph->check = nfq_checksum_tcpudp_ipv4(iph, IPPROTO_UDP); } EXPORT_SYMBOL(nfq_udp_compute_checksum_ipv4); @@ -115,7 +115,7 @@ nfq_udp_compute_checksum_ipv6(struct udphdr *udph, struct ip6_hdr *ip6h) { /* checksum field in header needs to be zero for calculation. */ udph->check = 0; - udph->check = nfq_checksum_tcpudp_ipv6(ip6h, udph); + udph->check = nfq_checksum_tcpudp_ipv6(ip6h, udph, IPPROTO_UDP); } EXPORT_SYMBOL(nfq_udp_compute_checksum_ipv6); diff --git a/src/internal.h b/src/internal.h index 558d267..d648bfe 100644 --- a/src/internal.h +++ b/src/internal.h @@ -15,8 +15,9 @@ struct iphdr; struct ip6_hdr; uint16_t nfq_checksum(uint32_t sum, uint16_t *buf, int size); -uint16_t nfq_checksum_tcpudp_ipv4(struct iphdr *iph); -uint16_t nfq_checksum_tcpudp_ipv6(struct ip6_hdr *ip6h, void *transport_hdr); +uint16_t nfq_checksum_tcpudp_ipv4(struct iphdr *iph, uint16_t protonum); +uint16_t nfq_checksum_tcpudp_ipv6(struct ip6_hdr *ip6h, void *transport_hdr, + uint16_t protonum); struct pkt_buff { uint8_t *mac_header; -- cgit v1.2.3