[lvc-project] [PATCH 5.10/5.15/6.1/6.6/6.12/6.18] ipvs: skip ipv6 extension headers for csum checks
Nazar Kalashnikov
nazarkalashnikov0 at gmail.com
Tue Jun 16 09:30:23 MSK 2026
From: Julian Anastasov <ja at ssi.bg>
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 <ja at ssi.bg>
Signed-off-by: Florian Westphal <fw at strlen.de>
Signed-off-by: Nazar Kalashnikov <nazarkalashnikov0 at gmail.com>
---
Backport fix for CVE-2026-45850
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 83e452916403..63c78a1f3918 100644
--- a/net/netfilter/ipvs/ip_vs_proto_sctp.c
+++ b/net/netfilter/ipvs/ip_vs_proto_sctp.c
@@ -10,7 +10,8 @@
#include <net/ip_vs.h>
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 */
@@ -156,7 +157,7 @@ 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 */
@@ -185,19 +186,12 @@ 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 <net/ip_vs.h>
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 <net/ip6_checksum.h>
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");
--
2.47.3
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