From 1ed84e729cbd9cce9920babfb5bb6292b3d93b8d Mon Sep 17 00:00:00 2001 From: Julian Anastasov Date: Sat, 14 Feb 2026 22:58:49 +0800 Subject: [PATCH] ipvs: skip ipv6 extension headers for csum checks ANBZ: #36482 commit 05cfe9863ef049d98141dc2969eefde72fb07625 upstream. Protocol checksum validation fails for IPv6 if there are extension headers before the protocol header. iph->len already contains its offset, so use it to fix the problem. Fixes: 2906f66a5682 ("ipvs: SCTP Trasport Loadbalancing Support") Fixes: 0bbdd42b7efa ("IPVS: Extend protocol DNAT/SNAT and state handlers") Signed-off-by: Julian Anastasov Signed-off-by: Florian Westphal Fixes: CVE-2026-45850 Assisted-by: PatchPilot Signed-off-by: Xuan Zhuo --- net/netfilter/ipvs/ip_vs_proto_sctp.c | 18 ++++++------------ net/netfilter/ipvs/ip_vs_proto_tcp.c | 21 +++++++-------------- net/netfilter/ipvs/ip_vs_proto_udp.c | 20 +++++++------------- 3 files changed, 20 insertions(+), 39 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_proto_sctp.c b/net/netfilter/ipvs/ip_vs_proto_sctp.c index a0921adc31a9..dcef7cdfaaba 100644 --- a/net/netfilter/ipvs/ip_vs_proto_sctp.c +++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c @@ -10,7 +10,8 @@ #include static int -sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp); +sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp, + unsigned int sctphoff); static int sctp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb, @@ -108,7 +109,7 @@ sctp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, int ret; /* Some checks before mangling */ - if (!sctp_csum_check(cp->af, skb, pp)) + if (!sctp_csum_check(cp->af, skb, pp, sctphoff)) return 0; /* Call application helper if needed */ @@ -155,7 +156,7 @@ sctp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, int ret; /* Some checks before mangling */ - if (!sctp_csum_check(cp->af, skb, pp)) + if (!sctp_csum_check(cp->af, skb, pp, sctphoff)) return 0; /* Call application helper if needed */ @@ -183,19 +184,12 @@ sctp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, } static int -sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp) +sctp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp, + unsigned int sctphoff) { - unsigned int sctphoff; struct sctphdr *sh; __le32 cmp, val; -#ifdef CONFIG_IP_VS_IPV6 - if (af == AF_INET6) - sctphoff = sizeof(struct ipv6hdr); - else -#endif - sctphoff = ip_hdrlen(skb); - sh = (struct sctphdr *)(skb->data + sctphoff); cmp = sh->checksum; val = sctp_compute_cksum(skb, sctphoff); diff --git a/net/netfilter/ipvs/ip_vs_proto_tcp.c b/net/netfilter/ipvs/ip_vs_proto_tcp.c index 7da51390cea6..ede4fa3b63f5 100644 --- a/net/netfilter/ipvs/ip_vs_proto_tcp.c +++ b/net/netfilter/ipvs/ip_vs_proto_tcp.c @@ -29,7 +29,8 @@ #include static int -tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp); +tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp, + unsigned int tcphoff); static int tcp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb, @@ -166,7 +167,7 @@ tcp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, int ret; /* Some checks before mangling */ - if (!tcp_csum_check(cp->af, skb, pp)) + if (!tcp_csum_check(cp->af, skb, pp, tcphoff)) return 0; /* Call application helper if needed */ @@ -244,7 +245,7 @@ tcp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, int ret; /* Some checks before mangling */ - if (!tcp_csum_check(cp->af, skb, pp)) + if (!tcp_csum_check(cp->af, skb, pp, tcphoff)) return 0; /* @@ -301,17 +302,9 @@ tcp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, static int -tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp) +tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp, + unsigned int tcphoff) { - unsigned int tcphoff; - -#ifdef CONFIG_IP_VS_IPV6 - if (af == AF_INET6) - tcphoff = sizeof(struct ipv6hdr); - else -#endif - tcphoff = ip_hdrlen(skb); - switch (skb->ip_summed) { case CHECKSUM_NONE: skb->csum = skb_checksum(skb, tcphoff, skb->len - tcphoff, 0); @@ -322,7 +315,7 @@ tcp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp) if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr, skb->len - tcphoff, - ipv6_hdr(skb)->nexthdr, + IPPROTO_TCP, skb->csum)) { IP_VS_DBG_RL_PKT(0, af, pp, skb, 0, "Failed checksum for"); diff --git a/net/netfilter/ipvs/ip_vs_proto_udp.c b/net/netfilter/ipvs/ip_vs_proto_udp.c index 68260d91c988..ffbebda547fc 100644 --- a/net/netfilter/ipvs/ip_vs_proto_udp.c +++ b/net/netfilter/ipvs/ip_vs_proto_udp.c @@ -25,7 +25,8 @@ #include static int -udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp); +udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp, + unsigned int udphoff); static int udp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb, @@ -155,7 +156,7 @@ udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, int ret; /* Some checks before mangling */ - if (!udp_csum_check(cp->af, skb, pp)) + if (!udp_csum_check(cp->af, skb, pp, udphoff)) return 0; /* @@ -238,7 +239,7 @@ udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, int ret; /* Some checks before mangling */ - if (!udp_csum_check(cp->af, skb, pp)) + if (!udp_csum_check(cp->af, skb, pp, udphoff)) return 0; /* @@ -297,17 +298,10 @@ udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp, static int -udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp) +udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp, + unsigned int udphoff) { struct udphdr _udph, *uh; - unsigned int udphoff; - -#ifdef CONFIG_IP_VS_IPV6 - if (af == AF_INET6) - udphoff = sizeof(struct ipv6hdr); - else -#endif - udphoff = ip_hdrlen(skb); uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph); if (uh == NULL) @@ -325,7 +319,7 @@ udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp) if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr, &ipv6_hdr(skb)->daddr, skb->len - udphoff, - ipv6_hdr(skb)->nexthdr, + IPPROTO_UDP, skb->csum)) { IP_VS_DBG_RL_PKT(0, af, pp, skb, 0, "Failed checksum for"); -- Gitee