Re: [PATCH v1] ipvs: add checksum support for gue encapsulation

From: Julian Anastasov
Date: Fri May 24 2019 - 09:13:59 EST

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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@xxxxxxxxx>
> ---
> 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@xxxxxx>

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