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Re: [PATCH v5] ipvs: allow tunneling with gue encapsulation

To: Jacky Hu <hengqing.hu@xxxxxxxxx>
Subject: Re: [PATCH v5] ipvs: allow tunneling with gue encapsulation
Cc: jacky.hu@xxxxxxxxxxx, jason.niesz@xxxxxxxxxxx, "David S. Miller" <davem@xxxxxxxxxxxxx>, Alexey Kuznetsov <kuznet@xxxxxxxxxxxxx>, Hideaki YOSHIFUJI <yoshfuji@xxxxxxxxxxxxxx>, Wensong Zhang <wensong@xxxxxxxxxxxx>, Julian Anastasov <ja@xxxxxx>, Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>, Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxxxxxx>, Florian Westphal <fw@xxxxxxxxx>, netdev@xxxxxxxxxxxxxxx, lvs-devel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, netfilter-devel@xxxxxxxxxxxxxxx, coreteam@xxxxxxxxxxxxx
From: Simon Horman <horms@xxxxxxxxxxxx>
Date: Mon, 25 Mar 2019 11:46:40 +0100
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@xxxxxxxxx>
> ---
>  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
> 

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