ipvs: allow tunneling with gre encapsulation

windows real servers can handle gre tunnels, this patch allows
gre encapsulation with the tunneling method, thereby letting ipvs
be load balancer for windows-based services

Signed-off-by: Vadim Fedorenko <vfedorenko@yandex-team.ru>
---
  include/uapi/linux/ip_vs.h      |  1 +
  net/netfilter/ipvs/ip_vs_xmit.c | 76 +++++++++++++++++++++++++++++++++++++++++
  2 files changed, 77 insertions(+)

   *   IP Tunneling transmitter
   *
@@ -1153,6 +1184,18 @@ static inline int __tun_gso_type_mask(int encaps_af, int 
orig_af)
  		max_headroom += sizeof(struct udphdr) + gue_hdrlen;
  	}

+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
+		size_t gre_hdrlen;
+		__be16 tflags = 0;
+
+		if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
+			tflags |= TUNNEL_CSUM;
+
+		gre_hdrlen = gre_calc_hlen(tflags);
+
+		max_headroom += gre_hdrlen;
+	}
+
  	/* We only care about the df field if sysctl_pmtu_disc(ipvs) is set */
  	dfp = sysctl_pmtu_disc(ipvs) ? &df : NULL;
  	skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
@@ -1174,6 +1217,13 @@ static inline int __tun_gso_type_mask(int encaps_af, int 
orig_af)
  		}
  	}

+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
+		if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
+			gso_type |= SKB_GSO_GRE_CSUM;
+		else
+			gso_type |= SKB_GSO_GRE;
+	}
+
  	if (iptunnel_handle_offloads(skb, gso_type))
  		goto tx_error;

@@ -1194,6 +1244,9 @@ static inline int __tun_gso_type_mask(int encaps_af, int 
orig_af)
  		udp_set_csum(!check, skb, saddr, cp->daddr.ip, skb->len);
  	}

+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
+		ipvs_gre_encap(net, skb, cp, &next_protocol);
+	}

  	skb_push(skb, sizeof(struct iphdr));
  	skb_reset_network_header(skb);
@@ -1289,6 +1342,18 @@ static inline int __tun_gso_type_mask(int encaps_af, int 
orig_af)
  		max_headroom += sizeof(struct udphdr) + gue_hdrlen;
  	}

+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
+		size_t gre_hdrlen;
+		__be16 tflags = 0;
+
+		if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
+			tflags |= TUNNEL_CSUM;
+
+		gre_hdrlen = gre_calc_hlen(tflags);
+
+		max_headroom += gre_hdrlen;
+	}
+
  	skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
  					 &next_protocol, &payload_len,
  					 &dsfield, &ttl, NULL);
@@ -1308,6 +1373,13 @@ static inline int __tun_gso_type_mask(int encaps_af, int 
orig_af)
  		}
  	}

+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
+		if (tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
+			gso_type |= SKB_GSO_GRE_CSUM;
+		else
+			gso_type |= SKB_GSO_GRE;
+	}
+
  	if (iptunnel_handle_offloads(skb, gso_type))
  		goto tx_error;

@@ -1328,6 +1400,10 @@ static inline int __tun_gso_type_mask(int encaps_af, int 
orig_af)
  		udp6_set_csum(!check, skb, &saddr, &cp->daddr.in6, skb->len);
  	}

+	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
+		ipvs_gre_encap(net, skb, cp, &next_protocol);
+	}
+
  	skb_push(skb, sizeof(struct ipv6hdr));
  	skb_reset_network_header(skb);
  	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

Hello,

On Tue, 25 Jun 2019, Vadim Fedorenko wrote:

> windows real servers can handle gre tunnels, this patch allows
> gre encapsulation with the tunneling method, thereby letting ipvs
> be load balancer for windows-based services
> 
> Signed-off-by: Vadim Fedorenko <vfedorenko@yandex-team.ru>

	Looks like your patch is not encoded properly.
Check Documentation/process/email-clients.rst for your
mail client to avoid the format=flowed in Content-Type.
To be sure, send patch to yourself and try to apply it.
As alternative, use git send-email to send patches, for example:

git send-email --envelope-sender 'YOUR EMAIL' \
	[--suppress-from] [--confirm=always] \
	--to 'TO_EMAIL' --cc 'CC_EMAIL1' --cc 'CC_EMAIL2' \
	file_or_dir

	You can test it by sending first to yourself only.
Also, test every patch before sending for problems:

scripts/checkpatch.pl --strict file.patch

	It shows some problems you should fix.

	So, your patch works but you have to send v2 with
some changes...

> ---
>  include/uapi/linux/ip_vs.h      |  1 +
>  net/netfilter/ipvs/ip_vs_xmit.c | 76
>  +++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 77 insertions(+)
> 

> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index 71fc6d6..fad3f33 100644
> --- a/net/netfilter/ipvs/ip_vs_xmit.c
> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
> @@ -29,6 +29,7 @@
>  #include <linux/tcp.h>                  /* for tcphdr */
>  #include <net/ip.h>
>  #include <net/gue.h>
> +#include <net/gre.h>
>  #include <net/tcp.h>                    /* for csum_tcpudp_magic */
>  #include <net/udp.h>
>  #include <net/icmp.h>                   /* for icmp_send */
> @@ -389,6 +390,12 @@ static inline bool decrement_ttl(struct netns_ipvs *ipvs,
>  			    skb->ip_summed == CHECKSUM_PARTIAL)
>  				mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
>  		}
> +		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
> +			__be16 tflags = 0;

	Empty line needed

> +			if (dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
> +				tflags |= TUNNEL_CSUM;
> +			mtu -= gre_calc_hlen(tflags);
> +		}
>  		if (mtu < 68) {
>  			IP_VS_DBG_RL("%s(): mtu less than 68\n", __func__);
>  			goto err_put;
> @@ -549,6 +556,12 @@ static inline bool decrement_ttl(struct netns_ipvs *ipvs,
>  			    skb->ip_summed == CHECKSUM_PARTIAL)
>  				mtu -= GUE_PLEN_REMCSUM + GUE_LEN_PRIV;
>  		}
> +		if (dest->tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
> +			__be16 tflags = 0;

	Empty line needed

> +			if (dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
> +				tflags |= TUNNEL_CSUM;
> +			mtu -= gre_calc_hlen(tflags);
> +		}
>  		if (mtu < IPV6_MIN_MTU) {
>  			IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
>  				     IPV6_MIN_MTU);
> @@ -1079,6 +1092,24 @@ static inline int __tun_gso_type_mask(int encaps_af,
> int orig_af)
>  	return 0;
>  }
> 
> +static void
> +ipvs_gre_encap(struct net *net, struct sk_buff *skb,
> +	       struct ip_vs_conn *cp, __u8 *next_protocol)
> +{
> +	size_t hdrlen;
> +	__be16 tflags = 0;
> +	__be16 proto = *next_protocol == IPPROTO_IPIP ? htons(ETH_P_IP) :
> htons(ETH_P_IPV6);

	This line is too long. You can also order the lines from long
to short.

> +
> +	if (cp->dest->tun_flags & IP_VS_TUNNEL_ENCAP_FLAG_CSUM)
> +		tflags |= TUNNEL_CSUM;

	Many empty lines are not needed...

> +
> +	hdrlen = gre_calc_hlen(tflags);
> +
> +	gre_build_header(skb, hdrlen, tflags, proto, 0, 0);
> +
> +	*next_protocol = IPPROTO_GRE;
> +}
> +
>  /*
>   *   IP Tunneling transmitter
>   *

> @@ -1328,6 +1400,10 @@ static inline int __tun_gso_type_mask(int encaps_af,
> int orig_af)
>  		udp6_set_csum(!check, skb, &saddr, &cp->daddr.in6, skb->len);
>  	}
> 
> +	if (tun_type == IP_VS_CONN_F_TUNNEL_TYPE_GRE) {
> +		ipvs_gre_encap(net, skb, cp, &next_protocol);
> +	}

	Braces are not needed, at both places where ipvs_gre_encap is 
called.

> +
>  	skb_push(skb, sizeof(struct ipv6hdr));
>  	skb_reset_network_header(skb);
>  	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));

	As part of your patch, the new tunnel type should be registered 
also in ip_vs_rs_hash(), GRE will use port 0 just like IPIP, eg:

                case IP_VS_CONN_F_TUNNEL_TYPE_IPIP:
+               case IP_VS_CONN_F_TUNNEL_TYPE_GRE:
                        port = 0;
                        break;

	Then I'll post a patch for ip_vs_in_icmp() that strips
the GRE header from ICMP errors by adding ipvs_gre_decap().
I also created ipvsadm patch for GRE.

Regards

--
Julian Anastasov <ja@ssi.bg>