gue: Receive side for Generic UDP Encapsulation

This patch adds support receiving for GUE packets in the fou module. The
fou module now supports direct foo-over-udp (no encapsulation header)
and GUE. To support this a type parameter is added to the fou netlink
parameters.

For a GUE socket we define gue_udp_recv, gue_gro_receive, and
gue_gro_complete to handle the specifics of the GUE protocol. Most
of the code to manage and configure sockets is common with the fou.

Signed-off-by: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 187 insertions, 9 deletions

diff --git a/net/ipv4/fou.c b/net/ipv4/fou.c
index 7e2126a31f2e..efa70ad44906 100644
--- a/net/ipv4/fou.c
+++ b/net/ipv4/fou.c
@@ -7,6 +7,7 @@
 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <net/genetlink.h>
+#include <net/gue.h>
 #include <net/ip.h>
 #include <net/protocol.h>
 #include <net/udp.h>
@@ -27,6 +28,7 @@ struct fou {
 };
 
 struct fou_cfg {
+        u16 type;
         u8 protocol;
         struct udp_port_cfg udp_config;
 };
@@ -64,6 +66,41 @@ static int fou_udp_recv(struct sock *sk, struct sk_buff *skb)
                                           sizeof(struct udphdr));
 }
 
+static int gue_udp_recv(struct sock *sk, struct sk_buff *skb)
+{
+        struct fou *fou = fou_from_sock(sk);
+        size_t len;
+        struct guehdr *guehdr;
+        struct udphdr *uh;
+
+        if (!fou)
+                return 1;
+
+        len = sizeof(struct udphdr) + sizeof(struct guehdr);
+        if (!pskb_may_pull(skb, len))
+                goto drop;
+
+        uh = udp_hdr(skb);
+        guehdr = (struct guehdr *)&uh[1];
+
+        len += guehdr->hlen << 2;
+        if (!pskb_may_pull(skb, len))
+                goto drop;
+
+        if (guehdr->version != 0)
+                goto drop;
+
+        if (guehdr->flags) {
+                /* No support yet */
+                goto drop;
+        }
+
+        return fou_udp_encap_recv_deliver(skb, guehdr->next_hdr, len);
+drop:
+        kfree_skb(skb);
+        return 0;
+}
+
 static struct sk_buff **fou_gro_receive(struct sk_buff **head,
                                         struct sk_buff *skb)
 {
@@ -107,6 +144,112 @@ out_unlock:
         return err;
 }
 
+static struct sk_buff **gue_gro_receive(struct sk_buff **head,
+                                        struct sk_buff *skb)
+{
+        const struct net_offload **offloads;
+        const struct net_offload *ops;
+        struct sk_buff **pp = NULL;
+        struct sk_buff *p;
+        u8 proto;
+        struct guehdr *guehdr;
+        unsigned int hlen, guehlen;
+        unsigned int off;
+        int flush = 1;
+
+        off = skb_gro_offset(skb);
+        hlen = off + sizeof(*guehdr);
+        guehdr = skb_gro_header_fast(skb, off);
+        if (skb_gro_header_hard(skb, hlen)) {
+                guehdr = skb_gro_header_slow(skb, hlen, off);
+                if (unlikely(!guehdr))
+                        goto out;
+        }
+
+        proto = guehdr->next_hdr;
+
+        rcu_read_lock();
+        offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
+        ops = rcu_dereference(offloads[proto]);
+        if (WARN_ON(!ops || !ops->callbacks.gro_receive))
+                goto out_unlock;
+
+        guehlen = sizeof(*guehdr) + (guehdr->hlen << 2);
+
+        hlen = off + guehlen;
+        if (skb_gro_header_hard(skb, hlen)) {
+                guehdr = skb_gro_header_slow(skb, hlen, off);
+                if (unlikely(!guehdr))
+                        goto out_unlock;
+        }
+
+        flush = 0;
+
+        for (p = *head; p; p = p->next) {
+                const struct guehdr *guehdr2;
+
+                if (!NAPI_GRO_CB(p)->same_flow)
+                        continue;
+
+                guehdr2 = (struct guehdr *)(p->data + off);
+
+                /* Compare base GUE header to be equal (covers
+                 * hlen, version, next_hdr, and flags.
+                 */
+                if (guehdr->word != guehdr2->word) {
+                        NAPI_GRO_CB(p)->same_flow = 0;
+                        continue;
+                }
+
+                /* Compare optional fields are the same. */
+                if (guehdr->hlen && memcmp(&guehdr[1], &guehdr2[1],
+                                           guehdr->hlen << 2)) {
+                        NAPI_GRO_CB(p)->same_flow = 0;
+                        continue;
+                }
+        }
+
+        skb_gro_pull(skb, guehlen);
+
+        /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
+        skb_gro_postpull_rcsum(skb, guehdr, guehlen);
+
+        pp = ops->callbacks.gro_receive(head, skb);
+
+out_unlock:
+        rcu_read_unlock();
+out:
+        NAPI_GRO_CB(skb)->flush |= flush;
+
+        return pp;
+}
+
+static int gue_gro_complete(struct sk_buff *skb, int nhoff)
+{
+        const struct net_offload **offloads;
+        struct guehdr *guehdr = (struct guehdr *)(skb->data + nhoff);
+        const struct net_offload *ops;
+        unsigned int guehlen;
+        u8 proto;
+        int err = -ENOENT;
+
+        proto = guehdr->next_hdr;
+
+        guehlen = sizeof(*guehdr) + (guehdr->hlen << 2);
+
+        rcu_read_lock();
+        offloads = NAPI_GRO_CB(skb)->is_ipv6 ? inet6_offloads : inet_offloads;
+        ops = rcu_dereference(offloads[proto]);
+        if (WARN_ON(!ops || !ops->callbacks.gro_complete))
+                goto out_unlock;
+
+        err = ops->callbacks.gro_complete(skb, nhoff + guehlen);
+
+out_unlock:
+        rcu_read_unlock();
+        return err;
+}
+
 static int fou_add_to_port_list(struct fou *fou)
 {
         struct fou *fout;
@@ -142,6 +285,28 @@ static void fou_release(struct fou *fou)
         kfree(fou);
 }
 
+static int fou_encap_init(struct sock *sk, struct fou *fou, struct fou_cfg *cfg)
+{
+        udp_sk(sk)->encap_rcv = fou_udp_recv;
+        fou->protocol = cfg->protocol;
+        fou->udp_offloads.callbacks.gro_receive = fou_gro_receive;
+        fou->udp_offloads.callbacks.gro_complete = fou_gro_complete;
+        fou->udp_offloads.port = cfg->udp_config.local_udp_port;
+        fou->udp_offloads.ipproto = cfg->protocol;
+
+        return 0;
+}
+
+static int gue_encap_init(struct sock *sk, struct fou *fou, struct fou_cfg *cfg)
+{
+        udp_sk(sk)->encap_rcv = gue_udp_recv;
+        fou->udp_offloads.callbacks.gro_receive = gue_gro_receive;
+        fou->udp_offloads.callbacks.gro_complete = gue_gro_complete;
+        fou->udp_offloads.port = cfg->udp_config.local_udp_port;
+
+        return 0;
+}
+
 static int fou_create(struct net *net, struct fou_cfg *cfg,
                       struct socket **sockp)
 {
@@ -164,10 +329,24 @@ static int fou_create(struct net *net, struct fou_cfg *cfg,
 
         sk = sock->sk;
 
-        /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */
-        fou->protocol = cfg->protocol;
-        fou->port =  cfg->udp_config.local_udp_port;
-        udp_sk(sk)->encap_rcv = fou_udp_recv;
+        fou->port = cfg->udp_config.local_udp_port;
+
+        /* Initial for fou type */
+        switch (cfg->type) {
+        case FOU_ENCAP_DIRECT:
+                err = fou_encap_init(sk, fou, cfg);
+                if (err)
+                        goto error;
+                break;
+        case FOU_ENCAP_GUE:
+                err = gue_encap_init(sk, fou, cfg);
+                if (err)
+                        goto error;
+                break;
+        default:
+                err = -EINVAL;
+                goto error;
+        }
 
         udp_sk(sk)->encap_type = 1;
         udp_encap_enable();
@@ -179,11 +358,6 @@ static int fou_create(struct net *net, struct fou_cfg *cfg,
 
         sk->sk_allocation = GFP_ATOMIC;
 
-        fou->udp_offloads.callbacks.gro_receive = fou_gro_receive;
-        fou->udp_offloads.callbacks.gro_complete = fou_gro_complete;
-        fou->udp_offloads.port = cfg->udp_config.local_udp_port;
-        fou->udp_offloads.ipproto = cfg->protocol;
-
         if (cfg->udp_config.family == AF_INET) {
                 err = udp_add_offload(&fou->udp_offloads);
                 if (err)
@@ -240,6 +414,7 @@ static struct nla_policy fou_nl_policy[FOU_ATTR_MAX + 1] = {
         [FOU_ATTR_PORT] = { .type = NLA_U16, },
         [FOU_ATTR_AF] = { .type = NLA_U8, },
         [FOU_ATTR_IPPROTO] = { .type = NLA_U8, },
+        [FOU_ATTR_TYPE] = { .type = NLA_U8, },
 };
 
 static int parse_nl_config(struct genl_info *info,
@@ -267,6 +442,9 @@ static int parse_nl_config(struct genl_info *info,
         if (info->attrs[FOU_ATTR_IPPROTO])
                 cfg->protocol = nla_get_u8(info->attrs[FOU_ATTR_IPPROTO]);
 
+        if (info->attrs[FOU_ATTR_TYPE])
+                cfg->type = nla_get_u8(info->attrs[FOU_ATTR_TYPE]);
+
         return 0;
 }