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Date:   Fri, 24 May 2019 16:09:49 +0300 (EEST)
From:   Julian Anastasov <ja@ssi.bg>
To:     Jacky Hu <hengqing.hu@gmail.com>
cc:     jacky.hu@walmart.com, jason.niesz@walmart.com,
        "David S. Miller" <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        Wensong Zhang <wensong@linux-vs.org>,
        Simon Horman <horms@verge.net.au>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        Florian Westphal <fw@strlen.de>, netdev@vger.kernel.org,
        lvs-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
        netfilter-devel@vger.kernel.org, coreteam@netfilter.org
Subject: Re: [PATCH v1] ipvs: add checksum support for gue encapsulation
In-Reply-To: <20190524025139.29732-1-hengqing.hu@gmail.com>
Message-ID: <alpine.LFD.2.21.1905241545410.3178@ja.home.ssi.bg>
References: <20190524025139.29732-1-hengqing.hu@gmail.com>
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	Hello,

On Fri, 24 May 2019, Jacky Hu wrote:

> Add checksum support for gue encapsulation with the tun_flags parameter,
> which could be one of the values below:
> IP_VS_TUNNEL_ENCAP_FLAG_NOCSUM
> IP_VS_TUNNEL_ENCAP_FLAG_CSUM
> IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM
> 
> Signed-off-by: Jacky Hu <hengqing.hu@gmail.com>
> ---
>  include/net/ip_vs.h             |   2 +
>  include/uapi/linux/ip_vs.h      |   7 ++
>  net/netfilter/ipvs/ip_vs_core.c |  56 +++++++++++++
>  net/netfilter/ipvs/ip_vs_ctl.c  |  11 ++-
>  net/netfilter/ipvs/ip_vs_xmit.c | 138 ++++++++++++++++++++++++++++----
>  5 files changed, 198 insertions(+), 16 deletions(-)
> 
> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> index b01a94ebfc0e..cb1ad0cc5c7b 100644
> --- a/include/net/ip_vs.h
> +++ b/include/net/ip_vs.h
> @@ -603,6 +603,7 @@ struct ip_vs_dest_user_kern {
>  
>  	u16			tun_type;	/* tunnel type */
>  	__be16			tun_port;	/* tunnel port */
> +	u16			tun_flags;	/* tunnel flags */
>  };
>  
>  
> @@ -665,6 +666,7 @@ struct ip_vs_dest {
>  	atomic_t		last_weight;	/* server latest weight */
>  	__u16			tun_type;	/* tunnel type */
>  	__be16			tun_port;	/* tunnel port */
> +	__u16			tun_flags;	/* tunnel flags */
>  
>  	refcount_t		refcnt;		/* reference counter */
>  	struct ip_vs_stats      stats;          /* statistics */
> diff --git a/include/uapi/linux/ip_vs.h b/include/uapi/linux/ip_vs.h
> index e34f436fc79d..fa5cf8498474 100644
> --- a/include/uapi/linux/ip_vs.h
> +++ b/include/uapi/linux/ip_vs.h
> @@ -131,6 +131,11 @@ enum {
>  	IP_VS_CONN_F_TUNNEL_TYPE_MAX,
>  };
>  
> +/* Tunnel encapsulation flags */
> +#define IP_VS_TUNNEL_ENCAP_FLAG_NOCSUM		(0)
> +#define IP_VS_TUNNEL_ENCAP_FLAG_CSUM		(1<<0)
> +#define IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM		(1<<1)
> +
>  /*
>   *	The struct ip_vs_service_user and struct ip_vs_dest_user are
>   *	used to set IPVS rules through setsockopt.
> @@ -403,6 +408,8 @@ enum {
>  
>  	IPVS_DEST_ATTR_TUN_PORT,	/* tunnel port */
>  
> +	IPVS_DEST_ATTR_TUN_FLAGS,	/* tunnel flags */
> +
>  	__IPVS_DEST_ATTR_MAX,
>  };
>  
> diff --git a/net/netfilter/ipvs/ip_vs_core.c b/net/netfilter/ipvs/ip_vs_core.c
> index d1d7b2483fd7..85e5ac363b52 100644
> --- a/net/netfilter/ipvs/ip_vs_core.c
> +++ b/net/netfilter/ipvs/ip_vs_core.c
> @@ -1580,6 +1580,29 @@ ip_vs_try_to_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
>  	return 1;
>  }
>  
> +static struct guehdr *gue_remcsum(struct sk_buff *skb, struct guehdr *guehdr,
> +				  void *data, size_t hdrlen, u8 ipproto,
> +				  bool nopartial)
> +{
> +	__be16 *pd = data;
> +	size_t start = ntohs(pd[0]);
> +	size_t offset = ntohs(pd[1]);
> +	size_t plen = sizeof(struct udphdr) + hdrlen +
> +	    max_t(size_t, offset + sizeof(u16), start);
> +
> +	if (skb->remcsum_offload)
> +		return guehdr;
> +
> +	if (!pskb_may_pull(skb, plen))
> +		return NULL;
> +	guehdr = (struct guehdr *)&udp_hdr(skb)[1];
> +
> +	skb_remcsum_process(skb, (void *)guehdr + hdrlen,
> +			    start, offset, nopartial);
> +
> +	return guehdr;
> +}
> +
>  /* Check the UDP tunnel and return its header length */
>  static int ipvs_udp_decap(struct netns_ipvs *ipvs, struct sk_buff *skb,
>  			  unsigned int offset, __u16 af,
> @@ -1597,6 +1620,9 @@ static int ipvs_udp_decap(struct netns_ipvs *ipvs, struct sk_buff *skb,
>  		goto unk;
>  	if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
>  		struct guehdr _gueh, *gueh;
> +		size_t optlen, hdrlen;
> +		void *data;
> +		u16 doffset = 0;
>  
>  		gueh = skb_header_pointer(skb, offset, sizeof(_gueh), &_gueh);
>  		if (!gueh)
> @@ -1606,7 +1632,37 @@ static int ipvs_udp_decap(struct netns_ipvs *ipvs, struct sk_buff *skb,
>  		/* Later we can support also IPPROTO_IPV6 */
>  		if (gueh->proto_ctype != IPPROTO_IPIP)
>  			goto unk;
> +
> +		optlen = gueh->hlen << 2;
> +		hdrlen = sizeof(struct guehdr) + optlen;
> +		data = &gueh[1];
> +
> +		if (gueh->flags & GUE_FLAG_PRIV) {
> +			__be32 flags = *(__be32 *)(data + doffset);
> +
> +			doffset += GUE_LEN_PRIV;
> +
> +			if (flags & GUE_PFLAG_REMCSUM) {
> +				gueh = gue_remcsum(skb, gueh,
> +						   data + doffset, hdrlen,
> +						   gueh->proto_ctype,
> +						   true);
> +				if (!gueh)
> +					goto unk;
> +
> +				data = &gueh[1];
> +
> +				doffset += GUE_PLEN_REMCSUM;
> +			}
> +		}
> +
>  		*proto = gueh->proto_ctype;
> +		__skb_pull(skb, sizeof(struct udphdr) + hdrlen);
> +		skb_reset_transport_header(skb);
> +
> +		if (iptunnel_pull_offloads(skb))
> +			goto unk;
> +
>  		return sizeof(struct udphdr) + sizeof(struct guehdr) +
>  		       (gueh->hlen << 2);
>  	}

	For the ICMP handling: we call icmp_send, __icmp_send,
icmp_push_reply, ip_append_data, __ip_append_data where
getfrag (icmp_glue_bits in our case) recalculates the
checksum. So, any checksum info in skb is simply ignored and
we do not need to change ip_vs_core.c.

> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index d5847e06350f..d7520179ac67 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -893,6 +893,7 @@ __ip_vs_update_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest,
>  	/* set the tunnel info */
>  	dest->tun_type = udest->tun_type;
>  	dest->tun_port = udest->tun_port;
> +	dest->tun_flags = udest->tun_flags;
>  
>  	/* set the IP_VS_CONN_F_NOOUTPUT flag if not masquerading/NAT */
>  	if ((conn_flags & IP_VS_CONN_F_FWD_MASK) != IP_VS_CONN_F_MASQ) {
> @@ -2967,6 +2968,7 @@ static const struct nla_policy ip_vs_dest_policy[IPVS_DEST_ATTR_MAX + 1] = {
>  	[IPVS_DEST_ATTR_ADDR_FAMILY]	= { .type = NLA_U16 },
>  	[IPVS_DEST_ATTR_TUN_TYPE]	= { .type = NLA_U8 },
>  	[IPVS_DEST_ATTR_TUN_PORT]	= { .type = NLA_U16 },
> +	[IPVS_DEST_ATTR_TUN_FLAGS]	= { .type = NLA_U8 },

	Lets work with U16

>  };
>  
>  static int ip_vs_genl_fill_stats(struct sk_buff *skb, int container_type,
> @@ -3273,6 +3275,8 @@ static int ip_vs_genl_fill_dest(struct sk_buff *skb, struct ip_vs_dest *dest)
>  		       dest->tun_type) ||
>  	    nla_put_be16(skb, IPVS_DEST_ATTR_TUN_PORT,
>  			 dest->tun_port) ||
> +	    nla_put_u8(skb, IPVS_DEST_ATTR_TUN_FLAGS,
> +		       dest->tun_flags) ||

	nla_put_u16

>  	    nla_put_u32(skb, IPVS_DEST_ATTR_U_THRESH, dest->u_threshold) ||
>  	    nla_put_u32(skb, IPVS_DEST_ATTR_L_THRESH, dest->l_threshold) ||
>  	    nla_put_u32(skb, IPVS_DEST_ATTR_ACTIVE_CONNS,
> @@ -3393,7 +3397,8 @@ static int ip_vs_genl_parse_dest(struct ip_vs_dest_user_kern *udest,
>  	/* If a full entry was requested, check for the additional fields */
>  	if (full_entry) {
>  		struct nlattr *nla_fwd, *nla_weight, *nla_u_thresh,
> -			      *nla_l_thresh, *nla_tun_type, *nla_tun_port;
> +			      *nla_l_thresh, *nla_tun_type, *nla_tun_port,
> +			      *nla_tun_flags;
>  
>  		nla_fwd		= attrs[IPVS_DEST_ATTR_FWD_METHOD];
>  		nla_weight	= attrs[IPVS_DEST_ATTR_WEIGHT];
> @@ -3401,6 +3406,7 @@ static int ip_vs_genl_parse_dest(struct ip_vs_dest_user_kern *udest,
>  		nla_l_thresh	= attrs[IPVS_DEST_ATTR_L_THRESH];
>  		nla_tun_type	= attrs[IPVS_DEST_ATTR_TUN_TYPE];
>  		nla_tun_port	= attrs[IPVS_DEST_ATTR_TUN_PORT];
> +		nla_tun_flags	= attrs[IPVS_DEST_ATTR_TUN_FLAGS];
>  
>  		if (!(nla_fwd && nla_weight && nla_u_thresh && nla_l_thresh))
>  			return -EINVAL;
> @@ -3416,6 +3422,9 @@ static int ip_vs_genl_parse_dest(struct ip_vs_dest_user_kern *udest,
>  
>  		if (nla_tun_port)
>  			udest->tun_port = nla_get_be16(nla_tun_port);
> +
> +		if (nla_tun_flags)
> +			udest->tun_flags = nla_get_u8(nla_tun_flags);

	nla_get_u16

>  	}
>  
>  	return 0;
> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index 8d6f94b67772..35fd7e5a9123 100644
> --- a/net/netfilter/ipvs/ip_vs_xmit.c
> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
> @@ -40,6 +40,7 @@
>  #include <net/ipv6.h>
>  #include <net/ip6_route.h>
>  #include <net/ip_tunnels.h>
> +#include <net/ip6_checksum.h>
>  #include <net/addrconf.h>
>  #include <linux/icmpv6.h>
>  #include <linux/netfilter.h>
> @@ -385,8 +386,13 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
>  		mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
>  		if (!dest)
>  			goto err_put;
> -		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> +		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
>  			mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
> +			if ((dest->tun_flags &
> +			     IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
> +			    skb->ip_summed == CHECKSUM_PARTIAL)
> +				mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
> +		}
>  		if (mtu < 68) {
>  			IP_VS_DBG_RL("%s(): mtu less than 68\n", __func__);
>  			goto err_put;
> @@ -540,8 +546,13 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
>  		mtu = dst_mtu(&rt->dst) - sizeof(struct ipv6hdr);
>  		if (!dest)
>  			goto err_put;
> -		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> +		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
>  			mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
> +			if ((dest->tun_flags &
> +			     IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
> +			    skb->ip_summed == CHECKSUM_PARTIAL)
> +				mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
> +		}
>  		if (mtu < IPV6_MIN_MTU) {
>  			IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
>  				     IPV6_MIN_MTU);
> @@ -1006,6 +1017,17 @@ ipvs_gue_encap(struct net *net, struct sk_buff *skb,
>  	__be16 sport = udp_flow_src_port(net, skb, 0, 0, false);
>  	struct udphdr  *udph;	/* Our new UDP header */
>  	struct guehdr  *gueh;	/* Our new GUE header */
> +	size_t hdrlen, optlen = 0;
> +	void *data;
> +	bool need_priv = false;
> +
> +	if ((cp->dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
> +	    skb->ip_summed == CHECKSUM_PARTIAL) {
> +		optlen += GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
> +		need_priv = true;
> +	}
> +
> +	hdrlen = sizeof(struct guehdr) + optlen;
>  
>  	skb_push(skb, sizeof(struct guehdr));

	We should use hdrlen:

	gueh = skb_push(skb, hdrlen);

>  
> @@ -1013,10 +1035,37 @@ ipvs_gue_encap(struct net *net, struct sk_buff *skb,
>  
>  	gueh->control = 0;
>  	gueh->version = 0;
> -	gueh->hlen = 0;
> +	gueh->hlen = optlen >> 2;
>  	gueh->flags = 0;
>  	gueh->proto_ctype = *next_protocol;
>  
> +	data = &gueh[1];
> +
> +	if (need_priv) {
> +		__be32 *flags = data;
> +		u16 csum_start = skb_checksum_start_offset(skb);
> +		__be16 *pd = data;
> +
> +		gueh->flags |= GUE_FLAG_PRIV;
> +		*flags = 0;
> +		data += GUE_LEN_PRIV;
> +
> +		if (csum_start < hdrlen)
> +			return -EINVAL;
> +
> +		csum_start -= hdrlen;
> +		pd[0] = htons(csum_start);
> +		pd[1] = htons(csum_start + skb->csum_offset);
> +
> +		if (!skb_is_gso(skb)) {
> +			skb->ip_summed = CHECKSUM_NONE;
> +			skb->encapsulation = 0;
> +		}
> +
> +		*flags |= GUE_PFLAG_REMCSUM;
> +		data += GUE_PLEN_REMCSUM;
> +	}
> +
>  	skb_push(skb, sizeof(struct udphdr));
>  	skb_reset_transport_header(skb);
>  
> @@ -1070,6 +1119,8 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
>  	unsigned int max_headroom;		/* The extra header space needed */
>  	int ret, local;
>  	int tun_type, gso_type;
> +	int tun_flags;
> +	size_t gue_hdrlen, gue_optlen = 0;
>  
>  	EnterFunction(10);
>  
> @@ -1092,9 +1143,17 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
>  	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);
>  
>  	tun_type = cp->dest->tun_type;
> +	tun_flags = cp->dest->tun_flags;
>  
> -	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> -		max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
> +	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {

	We can move gue_hdrlen and gue_optlen here.

> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
> +		    skb->ip_summed == CHECKSUM_PARTIAL) {
> +			gue_optlen += GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
> +		}
> +		gue_hdrlen = sizeof(struct guehdr) + gue_optlen;
> +
> +		max_headroom += sizeof(struct udphdr) + gue_hdrlen;
> +	}
>  
>  	/* We only care about the df field if sysctl_pmtu_disc(ipvs) is set */
>  	dfp = sysctl_pmtu_disc(ipvs) ? &df : NULL;
> @@ -1105,8 +1164,17 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
>  		goto tx_error;
>  
>  	gso_type = __tun_gso_type_mask(AF_INET, cp->af);
> -	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> -		gso_type |= SKB_GSO_UDP_TUNNEL;
> +	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
> +		    (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
> +			gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
> +		else
> +			gso_type |= SKB_GSO_UDP_TUNNEL;
> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
> +		    skb->ip_summed == CHECKSUM_PARTIAL) {
> +			gso_type |= SKB_GSO_TUNNEL_REMCSUM;
> +		}
> +	}
>  
>  	if (iptunnel_handle_offloads(skb, gso_type))
>  		goto tx_error;
> @@ -1115,8 +1183,19 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
>  
>  	skb_set_inner_ipproto(skb, next_protocol);
>  
> -	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> -		ipvs_gue_encap(net, skb, cp, &next_protocol);
> +	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
> +		bool check = false;
> +
> +		if (ipvs_gue_encap(net, skb, cp, &next_protocol))
> +			goto tx_error;
> +
> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
> +		    (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
> +			check = true;
> +
> +		udp_set_csum(!check, skb, saddr, cp->daddr.ip, skb->len);
> +	}
> +
>  
>  	skb_push(skb, sizeof(struct iphdr));
>  	skb_reset_network_header(skb);
> @@ -1174,6 +1253,8 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
>  	unsigned int max_headroom;	/* The extra header space needed */
>  	int ret, local;
>  	int tun_type, gso_type;
> +	int tun_flags;
> +	size_t gue_hdrlen, gue_optlen = 0;
>  
>  	EnterFunction(10);
>  
> @@ -1197,9 +1278,17 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
>  	max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr);
>  
>  	tun_type = cp->dest->tun_type;
> +	tun_flags = cp->dest->tun_flags;
> +
> +	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
> +		    skb->ip_summed == CHECKSUM_PARTIAL) {

	Same, we can move gue_hdrlen and gue_optlen here.

> +			gue_optlen += GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
> +		}
> +		gue_hdrlen = sizeof(struct guehdr) + gue_optlen;
>  
> -	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> -		max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
> +		max_headroom += sizeof(struct udphdr) + gue_hdrlen;
> +	}
>  
>  	skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
>  					 &next_protocol, &payload_len,
> @@ -1208,8 +1297,17 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
>  		goto tx_error;
>  
>  	gso_type = __tun_gso_type_mask(AF_INET6, cp->af);
> -	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> -		gso_type |= SKB_GSO_UDP_TUNNEL;
> +	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
> +		    (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
> +			gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
> +		else
> +			gso_type |= SKB_GSO_UDP_TUNNEL;
> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM) &&
> +		    skb->ip_summed == CHECKSUM_PARTIAL) {
> +			gso_type |= SKB_GSO_TUNNEL_REMCSUM;
> +		}
> +	}
>  
>  	if (iptunnel_handle_offloads(skb, gso_type))
>  		goto tx_error;
> @@ -1218,8 +1316,18 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
>  
>  	skb_set_inner_ipproto(skb, next_protocol);
>  
> -	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE)
> -		ipvs_gue_encap(net, skb, cp, &next_protocol);
> +	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GUE) {
> +		bool check = false;
> +
> +		if (ipvs_gue_encap(net, skb, cp, &next_protocol))
> +			goto tx_error;
> +
> +		if ((tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM) ||
> +		    (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_REMCSUM))
> +			check = true;
> +
> +		udp6_set_csum(!check, skb, &saddr, &cp->daddr.in6, skb->len);
> +	}
>  
>  	skb_push(skb, sizeof(struct ipv6hdr));
>  	skb_reset_network_header(skb);
> -- 
> 2.21.0

Regards

--
Julian Anastasov <ja@ssi.bg>