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Message-ID: <7a1903c5-f7e3-4480-2a07-ae94e4d6a895@ssi.bg>
Date: Tue, 11 Feb 2025 15:55:07 +0200 (EET)
From: Julian Anastasov <ja@....bg>
To: mengkanglai <mengkanglai2@...wei.com>
cc: Pablo Neira Ayuso <pablo@...filter.org>,
Jozsef Kadlecsik <kadlec@...filter.org>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>,
"netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
"coreteam@...filter.org" <coreteam@...filter.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Yanan (Euler)" <yanan@...wei.com>,
"Fengtao (fengtao, Euler)" <fengtao40@...wei.com>,
"gaoxingwang (A)" <gaoxingwang1@...wei.com>, lvs-devel@...r.kernel.org
Subject: Re: ftp ipvs connect failed in ipv6
Hello,
On Mon, 10 Feb 2025, mengkanglai wrote:
> Hello:
> I found a problem with ftp ipvs.
> I create 3 virtual machine in one host. One is the FTP client, the other is the ipvs transition host, and the other is the FTP server.
> The ftp connection is successful in ipv4 address,but failed in ipv6 address.
> The failure is tcp6 checksum error in tcp_dnat_handler(tcp_dnat_handler-> tcp_csum_check->csum_ipv6_magic),
> I trace back where skb->csum is assigned and found skb->csum is assigned in nf_ip6_checksum in case CHECKSUM_NONE(ipv6_conntrack_in=> nf_conntrack_in => nf_conntrack_tcp_packet => nf_ip6_checksum).
> I don't know much about ipv6 checksums,why ipv6 nf_conntrack assign skb->csum but check error in ipvs tcp_dnat_handler?
Looks like the checksum validation does not use correct
offset for the protocol header in the case with IPv6. Do you
see extension headers before the final IPv6 header that
points to TCP header? If that is the case, the following patch
can help. If you prefer, you can apply just the TCP part for
the FTP test. Let me know if this solves the problem, thanks!
[PATCH] ipvs: provide correct ipv6 proto offset for csum checks
Protocol checksum validation fails if there are multiple IPv6 headers
before the protocol header. iph->len already contains its offset, so
use it to fix the problem.
Signed-off-by: Julian Anastasov <ja@....bg>
---
net/netfilter/ipvs/ip_vs_proto_sctp.c | 18 ++++++------------
net/netfilter/ipvs/ip_vs_proto_tcp.c | 19 ++++++-------------
net/netfilter/ipvs/ip_vs_proto_udp.c | 18 ++++++------------
3 files changed, 18 insertions(+), 37 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..dabdb9d3b479 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);
diff --git a/net/netfilter/ipvs/ip_vs_proto_udp.c b/net/netfilter/ipvs/ip_vs_proto_udp.c
index 68260d91c988..e99e7c5df869 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)
--
2.48.1
Regards
--
Julian Anastasov <ja@....bg>
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