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

From: Julian Anastasov
Date: Wed Mar 13 2019 - 15:30:11 EST

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In reply to: Jacky Hu: "[PATCH] ipvs: allow tunneling with gue encapsulation"
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Hello,

On Tue, 12 Mar 2019, 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/uapi/linux/ip_vs.h | 17 +++++++-
> net/netfilter/ipvs/ip_vs_ctl.c | 4 +-
> net/netfilter/ipvs/ip_vs_xmit.c | 71 ++++++++++++++++++++++++++++++++-
> 3 files changed, 87 insertions(+), 5 deletions(-)
>
> diff --git a/include/uapi/linux/ip_vs.h b/include/uapi/linux/ip_vs.h
> index 1c916b2f89dc..6637e45b93f4 100644
> --- a/include/uapi/linux/ip_vs.h
> +++ b/include/uapi/linux/ip_vs.h
> @@ -96,13 +96,25 @@
> #define IP_VS_CONN_F_TEMPLATE 0x1000 /* template, not connection */
> #define IP_VS_CONN_F_ONE_PACKET 0x2000 /* forward only one packet */
>
> +/* tunneling with gue */
> +#define IP_VS_CONN_F_GUE 0x0008
> +
> +/* gue destination port bit 0 */
> +#define IP_VS_CONN_F_GUE_PORT_LSB 0x4000
> +
> +/* gue destination port bit 1-15 */
> +#define IP_VS_CONN_F_GUE_PORT_MSB 0xFFFFE0000
> +
> /* Initial bits allowed in backup server */
> #define IP_VS_CONN_F_BACKUP_MASK (IP_VS_CONN_F_FWD_MASK | \
> IP_VS_CONN_F_NOOUTPUT | \
> IP_VS_CONN_F_INACTIVE | \
> IP_VS_CONN_F_SEQ_MASK | \
> IP_VS_CONN_F_NO_CPORT | \
> - IP_VS_CONN_F_TEMPLATE \
> + IP_VS_CONN_F_TEMPLATE | \
> + IP_VS_CONN_F_GUE | \
> + IP_VS_CONN_F_GUE_PORT_MSB | \
> + IP_VS_CONN_F_GUE_PORT_LSB \
> )
>
> /* Bits allowed to update in backup server */
> @@ -116,6 +128,9 @@
> #define IP_VS_CONN_F_DEST_MASK (IP_VS_CONN_F_FWD_MASK | \
> IP_VS_CONN_F_ONE_PACKET | \
> IP_VS_CONN_F_NFCT | \
> + IP_VS_CONN_F_GUE | \
> + IP_VS_CONN_F_GUE_PORT_MSB | \
> + IP_VS_CONN_F_GUE_PORT_LSB | \
> 0)

It would be better to not touch these flags. The backup
sync server simply ignores the forwarding method by applying the
IP_VS_CONN_F_BACKUP_UPD_MASK mask. The real server is found only
by daddr+dport. It would be enough to provide any new non-default
parameters as optional IPVS_DEST_ATTR_xxx attributes. By this way,
we can later add more tunneling methods.

> #define IP_VS_SCHEDNAME_MAXLEN 16
> diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
> index 432141f04af3..cecfb52cdea4 100644
> --- a/net/netfilter/ipvs/ip_vs_ctl.c
> +++ b/net/netfilter/ipvs/ip_vs_ctl.c
> @@ -3169,7 +3169,7 @@ static int ip_vs_genl_fill_dest(struct sk_buff *skb, struct ip_vs_dest *dest)
> nla_put_be16(skb, IPVS_DEST_ATTR_PORT, dest->port) ||
> nla_put_u32(skb, IPVS_DEST_ATTR_FWD_METHOD,
> (atomic_read(&dest->conn_flags) &
> - IP_VS_CONN_F_FWD_MASK)) ||
> + IP_VS_CONN_F_DEST_MASK)) ||
> nla_put_u32(skb, IPVS_DEST_ATTR_WEIGHT,
> atomic_read(&dest->weight)) ||
> nla_put_u32(skb, IPVS_DEST_ATTR_U_THRESH, dest->u_threshold) ||

We can add the new attributes in this function.

> @@ -3305,7 +3305,7 @@ static int ip_vs_genl_parse_dest(struct ip_vs_dest_user_kern *udest,
> return -EINVAL;
>
> udest->conn_flags = nla_get_u32(nla_fwd)
> - & IP_VS_CONN_F_FWD_MASK;
> + & IP_VS_CONN_F_DEST_MASK;
> 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);

Here too.

Also, note that __ip_vs_update_dest() can update the forwarding
methods, so we should be able to switch them between any method.

> diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c
> index 473cce2a5231..2667b587b91d 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 */
> @@ -989,6 +990,42 @@ static inline int __tun_gso_type_mask(int encaps_af, int orig_af)
> }
> }
>
> +static int
> +__build_gue_header(struct net *net, struct sk_buff *skb,
> + struct ip_vs_conn *cp, __u8 *next_protocol)
> +{
> + __be16 dport;
> + __be16 sport;
> + 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 = htons(((cp->flags >> 16) & 0xFFFE) | ((cp->flags >> 14) & 1));
> + sport = udp_flow_src_port(net, skb, 0, 0, false);
> + 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 +1062,8 @@ 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;
> + bool gue = false;
> + int type;
>
> EnterFunction(10);
>
> @@ -1041,11 +1080,16 @@ ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp,
> rt = skb_rtable(skb);
> tdev = rt->dst.dev;
>

Then, in this func we should drop traffic when cp->dest is NULL
because we will not know the actual tunneling method. But it can happen
only on misconfigured backup servers, so this is not a big problem.

Now, the parameters should be available in cp->dest.

> + gue = (bool)(cp->flags & IP_VS_CONN_F_GUE);
> +
> /*
> * Okay, now see if we can stuff it in the buffer as-is.
> */
> max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr);
>
> + if (gue)
> + max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
> +
> /* 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 +1098,19 @@ 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)))
> + if (gue)
> + type = SKB_GSO_UDP_TUNNEL;
> + else
> + type = __tun_gso_type_mask(AF_INET, cp->af);
> +
> + if (iptunnel_handle_offloads(skb, type))
> goto tx_error;
>
> skb->transport_header = skb->network_header;
>
> + if (gue)
> + __build_gue_header(dev_net(tdev), skb, cp, &next_protocol);
> +
> skb_push(skb, sizeof(struct iphdr));
> skb_reset_network_header(skb);
> memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
> @@ -1112,6 +1164,8 @@ 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;
> + bool gue = false;
> + int type;
>
> EnterFunction(10);
>
> @@ -1129,22 +1183,35 @@ ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp,
> rt = (struct rt6_info *) skb_dst(skb);
> tdev = rt->dst.dev;
>
> + gue = (bool)(cp->flags & IP_VS_CONN_F_GUE);
> +
> /*
> * Okay, now see if we can stuff it in the buffer as-is.
> */
> max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr);
>
> + if (gue)
> + max_headroom += sizeof(struct udphdr) + sizeof(struct guehdr);
> +
> 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)))
> + if (gue)
> + type = SKB_GSO_UDP_TUNNEL;
> + else
> + type = __tun_gso_type_mask(AF_INET6, cp->af);
> +
> + if (iptunnel_handle_offloads(skb, type))
> goto tx_error;
>
> skb->transport_header = skb->network_header;
>
> + if (gue)
> + __build_gue_header(dev_net(tdev), skb, cp, &next_protocol);
> +
> skb_push(skb, sizeof(struct ipv6hdr));
> skb_reset_network_header(skb);
> memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
> --
> 2.21.0

Regards

--
Julian Anastasov <ja@xxxxxx>

Next message: Sasha Levin: "[PATCH AUTOSEL 4.20 52/60] net: thunderx: make CFG_DONE message to run through generic send-ack sequence"
Previous message: Sasha Levin: "[PATCH AUTOSEL 4.20 53/60] net: thunderx: add nicvf_send_msg_to_pf result check for set_rx_mode_task"
In reply to: Jacky Hu: "[PATCH] ipvs: allow tunneling with gue encapsulation"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]