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Date:   Mon, 25 Mar 2019 11:46:40 +0100
From:   Simon Horman <horms@verge.net.au>
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>,
        Julian Anastasov <ja@ssi.bg>,
        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 v5] ipvs: allow tunneling with gue encapsulation
Message-ID: <20190325104639.guok6lrmn6vwg3e6@verge.net.au>
References: <20190319052656.23933-1-hengqing.hu@gmail.com>
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In-Reply-To: <20190319052656.23933-1-hengqing.hu@gmail.com>
Organisation: Horms Solutions BV
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Sender: linux-kernel-owner@vger.kernel.org
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On Tue, Mar 19, 2019 at 01:26:55PM +0800, Jacky Hu wrote:
> ipip packets are blocked in some public cloud environments, this patch
> allows gue encapsulation with the tunneling method, which would make
> tunneling working in those environments.
> 
> Signed-off-by: Jacky Hu <hengqing.hu@gmail.com>
> ---
>  include/net/ip_vs.h             |   5 ++
>  include/uapi/linux/ip_vs.h      |  11 +++
>  net/netfilter/ipvs/ip_vs_ctl.c  |  43 ++++++++++-
>  net/netfilter/ipvs/ip_vs_xmit.c | 124 ++++++++++++++++++++++++++++++--
>  4 files changed, 178 insertions(+), 5 deletions(-)
> 
> diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
> index a0d2e0bb9a94..cdc7b621930d 100644
> --- a/include/net/ip_vs.h
> +++ b/include/net/ip_vs.h
> @@ -603,6 +603,9 @@ struct ip_vs_dest_user_kern {
>  
>  	/* Address family of addr */
>  	u16			af;
> +
> +	u16			tun_type;	/* tunnel type */
> +	__be16			tun_port;	/* tunnel port */
>  };
>  
>  
> @@ -663,6 +666,8 @@ struct ip_vs_dest {
>  	atomic_t		conn_flags;	/* flags to copy to conn */
>  	atomic_t		weight;		/* server weight */
>  	atomic_t		last_weight;	/* server latest weight */
> +	__u16			tun_type;	/* tunnel type */
> +	__be16			tun_port;	/* tunnel port */
>  
>  	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 1c916b2f89dc..e34f436fc79d 100644
> --- a/include/uapi/linux/ip_vs.h
> +++ b/include/uapi/linux/ip_vs.h
> @@ -124,6 +124,13 @@
>  
>  #define IP_VS_PEDATA_MAXLEN     255
>  
> +/* Tunnel types */
> +enum {
> +	IP_VS_CONN_F_TUNNEL_TYPE_IPIP = 0,	/* IPIP */
> +	IP_VS_CONN_F_TUNNEL_TYPE_GUE,		/* GUE */
> +	IP_VS_CONN_F_TUNNEL_TYPE_MAX,
> +};
> +
>  /*
>   *	The struct ip_vs_service_user and struct ip_vs_dest_user are
>   *	used to set IPVS rules through setsockopt.
> @@ -392,6 +399,10 @@ enum {
>  
>  	IPVS_DEST_ATTR_STATS64,		/* nested attribute for dest stats */
>  
> +	IPVS_DEST_ATTR_TUN_TYPE,	/* tunnel type */
> +
> +	IPVS_DEST_ATTR_TUN_PORT,	/* tunnel port */
> +
>  	__IPVS_DEST_ATTR_MAX,
>  };
>  
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 432141f04af3..ddee6266b78b 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -830,6 +830,10 @@ __ip_vs_update_dest(struct ip_vs_service *svc, struct ip_vs_dest *dest,
>  	conn_flags = udest->conn_flags & IP_VS_CONN_F_DEST_MASK;
>  	conn_flags |= IP_VS_CONN_F_INACTIVE;
>  
> +	/* set the tunnel info */
> +	dest->tun_type = udest->tun_type;
> +	dest->tun_port = udest->tun_port;
> +
>  	/* 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) {
>  		conn_flags |= IP_VS_CONN_F_NOOUTPUT;
> @@ -980,6 +984,17 @@ ip_vs_add_dest(struct ip_vs_service *svc, struct ip_vs_dest_user_kern *udest)
>  		return -ERANGE;
>  	}
>  
> +	switch (udest->tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:

Given that tun_type check acts on an integer, as opposed to an enum,
I don't see that using a switch statement gives us much here,
and throughout the patch, other than extra verbosity.

Did you consider simply using an if statement?

> +		if (udest->tun_port == 0) {
> +			pr_err("%s(): tunnel port is zero\n", __func__);
> +			return -EINVAL;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +
>  	ip_vs_addr_copy(udest->af, &daddr, &udest->addr);
>  
>  	/* We use function that requires RCU lock */
> @@ -1044,6 +1059,17 @@ ip_vs_edit_dest(struct ip_vs_service *svc, struct ip_vs_dest_user_kern *udest)
>  		return -ERANGE;
>  	}
>  
> +	switch (udest->tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +		if (udest->tun_port == 0) {
> +			pr_err("%s(): tunnel port is zero\n", __func__);
> +			return -EINVAL;
> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +
>  	ip_vs_addr_copy(udest->af, &daddr, &udest->addr);
>  
>  	/* We use function that requires RCU lock */
> @@ -2310,6 +2336,7 @@ static void ip_vs_copy_udest_compat(struct ip_vs_dest_user_kern *udest,
>  	udest->u_threshold	= udest_compat->u_threshold;
>  	udest->l_threshold	= udest_compat->l_threshold;
>  	udest->af		= AF_INET;
> +	udest->tun_type		= IP_VS_CONN_F_TUNNEL_TYPE_IPIP;
>  }
>  
>  static int
> @@ -2869,6 +2896,8 @@ static const struct nla_policy ip_vs_dest_policy[IPVS_DEST_ATTR_MAX + 1] = {
>  	[IPVS_DEST_ATTR_PERSIST_CONNS]	= { .type = NLA_U32 },
>  	[IPVS_DEST_ATTR_STATS]		= { .type = NLA_NESTED },
>  	[IPVS_DEST_ATTR_ADDR_FAMILY]	= { .type = NLA_U16 },
> +	[IPVS_DEST_ATTR_TUN_TYPE]	= { .type = NLA_U8 },
> +	[IPVS_DEST_ATTR_TUN_PORT]	= { .type = NLA_U16 },
>  };
>  
>  static int ip_vs_genl_fill_stats(struct sk_buff *skb, int container_type,
> @@ -3172,6 +3201,10 @@ static int ip_vs_genl_fill_dest(struct sk_buff *skb, struct ip_vs_dest *dest)
>  			 IP_VS_CONN_F_FWD_MASK)) ||
>  	    nla_put_u32(skb, IPVS_DEST_ATTR_WEIGHT,
>  			atomic_read(&dest->weight)) ||
> +	    nla_put_u8(skb, IPVS_DEST_ATTR_TUN_TYPE,
> +		       dest->tun_type) ||
> +	    nla_put_be16(skb, IPVS_DEST_ATTR_TUN_PORT,
> +			 dest->tun_port) ||
>  	    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,
> @@ -3294,12 +3327,14 @@ 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_l_thresh, *nla_tun_type, *nla_tun_port;
>  
>  		nla_fwd		= attrs[IPVS_DEST_ATTR_FWD_METHOD];
>  		nla_weight	= attrs[IPVS_DEST_ATTR_WEIGHT];
>  		nla_u_thresh	= attrs[IPVS_DEST_ATTR_U_THRESH];
>  		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];
>  
>  		if (!(nla_fwd && nla_weight && nla_u_thresh && nla_l_thresh))
>  			return -EINVAL;
> @@ -3309,6 +3344,12 @@ static int ip_vs_genl_parse_dest(struct ip_vs_dest_user_kern *udest,
>  		udest->weight = nla_get_u32(nla_weight);
>  		udest->u_threshold = nla_get_u32(nla_u_thresh);
>  		udest->l_threshold = nla_get_u32(nla_l_thresh);
> +
> +		if (nla_tun_type)
> +			udest->tun_type = nla_get_u8(nla_tun_type);
> +
> +		if (nla_tun_port)
> +			udest->tun_port = nla_get_be16(nla_tun_port);
>  	}
>  
>  	return 0;
> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index 473cce2a5231..730e108b9f36 100644
> --- a/net/netfilter/ipvs/ip_vs_xmit.c
> +++ b/net/netfilter/ipvs/ip_vs_xmit.c
> @@ -32,6 +32,7 @@
>  #include <linux/slab.h>
>  #include <linux/tcp.h>                  /* for tcphdr */
>  #include <net/ip.h>
> +#include <net/gue.h>
>  #include <net/tcp.h>                    /* for csum_tcpudp_magic */
>  #include <net/udp.h>
>  #include <net/icmp.h>                   /* for icmp_send */
> @@ -382,6 +383,15 @@ __ip_vs_get_out_rt(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
>  		mtu = dst_mtu(&rt->dst);
>  	} else {
>  		mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr);
> +		if (!dest)
> +			goto err_put;
> +		switch (dest->tun_type) {
> +		case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +			mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
> +			break;
> +		default:
> +			break;
> +		}
>  		if (mtu < 68) {
>  			IP_VS_DBG_RL("%s(): mtu less than 68\n", __func__);
>  			goto err_put;
> @@ -533,6 +543,15 @@ __ip_vs_get_out_rt_v6(struct netns_ipvs *ipvs, int skb_af, struct sk_buff *skb,
>  		mtu = dst_mtu(&rt->dst);
>  	else {
>  		mtu = dst_mtu(&rt->dst) - sizeof(struct ipv6hdr);
> +		if (!dest)
> +			goto err_put;
> +		switch (dest->tun_type) {
> +		case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +			mtu -= sizeof(struct udphdr) + sizeof(struct guehdr);
> +			break;
> +		default:
> +			break;
> +		}
>  		if (mtu < IPV6_MIN_MTU) {
>  			IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__,
>  				     IPV6_MIN_MTU);
> @@ -989,6 +1008,41 @@ static inline int __tun_gso_type_mask(int encaps_af, int orig_af)
>  	}
>  }
>  
> +static int
> +ipvs_gue_encap(struct net *net, struct sk_buff *skb,
> +	       struct ip_vs_conn *cp, __u8 *next_protocol)
> +{
> +	__be16 dport;
> +	__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 */
> +
> +	skb_push(skb, sizeof(struct guehdr));
> +
> +	gueh = (struct guehdr *)skb->data;
> +
> +	gueh->control = 0;
> +	gueh->version = 0;
> +	gueh->hlen = 0;
> +	gueh->flags = 0;
> +	gueh->proto_ctype = *next_protocol;
> +
> +	skb_push(skb, sizeof(struct udphdr));
> +	skb_reset_transport_header(skb);
> +
> +	udph = udp_hdr(skb);
> +
> +	dport = cp->dest->tun_port;
> +	udph->dest = dport;
> +	udph->source = sport;
> +	udph->len = htons(skb->len);
> +	udph->check = 0;
> +
> +	*next_protocol = IPPROTO_UDP;
> +
> +	return 0;
> +}
> +
>  /*
>   *   IP Tunneling transmitter
>   *
> @@ -1025,6 +1079,7 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
>  	struct iphdr  *iph;			/* Our new IP header */
>  	unsigned int max_headroom;		/* The extra header space needed */
>  	int ret, local;
> +	int tun_type, gso_type;
>  
>  	EnterFunction(10);
>  
> @@ -1046,6 +1101,16 @@ 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;
> +
> +	switch (tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +		max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
> +		break;
> +	default:
> +		break;
> +	}
> +
>  	/* 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,
> @@ -1054,11 +1119,30 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
>  	if (IS_ERR(skb))
>  		goto tx_error;
>  
> -	if (iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET, cp->af)))
> +	switch (tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +		gso_type = SKB_GSO_UDP_TUNNEL;
> +		break;
> +	default:
> +		gso_type = __tun_gso_type_mask(AF_INET, cp->af);
> +		break;
> +	}
> +
> +	if (iptunnel_handle_offloads(skb, gso_type))
>  		goto tx_error;
>  
>  	skb->transport_header = skb->network_header;
>  
> +	skb_set_inner_ipproto(skb, next_protocol);
> +
> +	switch (tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +		ipvs_gue_encap(net, skb, cp, &next_protocol);
> +		break;
> +	default:
> +		break;
> +	}
> +
>  	skb_push(skb, sizeof(struct iphdr));
>  	skb_reset_network_header(skb);
>  	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
> @@ -1102,6 +1186,8 @@ int
>  ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
>  		     struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh)
>  {
> +	struct netns_ipvs *ipvs = cp->ipvs;
> +	struct net *net = ipvs->net;
>  	struct rt6_info *rt;		/* Route to the other host */
>  	struct in6_addr saddr;		/* Source for tunnel */
>  	struct net_device *tdev;	/* Device to other host */
> @@ -1112,10 +1198,11 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
>  	struct ipv6hdr  *iph;		/* Our new IP header */
>  	unsigned int max_headroom;	/* The extra header space needed */
>  	int ret, local;
> +	int tun_type, gso_type;
>  
>  	EnterFunction(10);
>  
> -	local = __ip_vs_get_out_rt_v6(cp->ipvs, cp->af, skb, cp->dest,
> +	local = __ip_vs_get_out_rt_v6(ipvs, cp->af, skb, cp->dest,
>  				      &cp->daddr.in6,
>  				      &saddr, ipvsh, 1,
>  				      IP_VS_RT_MODE_LOCAL |
> @@ -1134,17 +1221,46 @@ 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;
> +
> +	switch (tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +		max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
> +		break;
> +	default:
> +		break;
> +	}
> +
>  	skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom,
>  					 &next_protocol, &payload_len,
>  					 &dsfield, &ttl, NULL);
>  	if (IS_ERR(skb))
>  		goto tx_error;
>  
> -	if (iptunnel_handle_offloads(skb, __tun_gso_type_mask(AF_INET6, cp->af)))
> +	switch (tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +		gso_type = SKB_GSO_UDP_TUNNEL;
> +		break;
> +	default:
> +		gso_type = __tun_gso_type_mask(AF_INET6, cp->af);
> +		break;
> +	}
> +
> +	if (iptunnel_handle_offloads(skb, gso_type))
>  		goto tx_error;
>  
>  	skb->transport_header = skb->network_header;
>  
> +	skb_set_inner_ipproto(skb, next_protocol);
> +
> +	switch (tun_type) {
> +	case IP_VS_CONN_F_TUNNEL_TYPE_GUE:
> +		ipvs_gue_encap(net, skb, cp, &next_protocol);
> +		break;
> +	default:
> +		break;
> +	}
> +
>  	skb_push(skb, sizeof(struct ipv6hdr));
>  	skb_reset_network_header(skb);
>  	memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
> @@ -1167,7 +1283,7 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
>  
>  	ret = ip_vs_tunnel_xmit_prepare(skb, cp);
>  	if (ret == NF_ACCEPT)
> -		ip6_local_out(cp->ipvs->net, skb->sk, skb);
> +		ip6_local_out(net, skb->sk, skb);
>  	else if (ret == NF_DROP)
>  		kfree_skb(skb);
>  
> -- 
> 2.21.0
>