[Patch bpf-next v2 4/9] udp: implement ->read_sock() for sockmap

[Cong Wang]

From: Cong Wang <cong.w...@bytedance.com>

Cc: John Fastabend <john.fastab...@gmail.com>
Cc: Daniel Borkmann <dan...@iogearbox.net>
Cc: Jakub Sitnicki <ja...@cloudflare.com>
Cc: Lorenz Bauer <l...@cloudflare.com>
Signed-off-by: Cong Wang <cong.w...@bytedance.com>
---
 include/net/udp.h  |  2 ++
 net/ipv4/af_inet.c |  1 +
 net/ipv4/udp.c     | 34 ++++++++++++++++++++++++++++++++++
 3 files changed, 37 insertions(+)

diff --git a/include/net/udp.h b/include/net/udp.h
index 5264ba1439f9..44a94cfc63b5 100644
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -330,6 +330,8 @@ struct sock *__udp6_lib_lookup(struct net *net,
                               struct sk_buff *skb);
 struct sock *udp6_lib_lookup_skb(const struct sk_buff *skb,
                                 __be16 sport, __be16 dport);
+int udp_read_sock(struct sock *sk, read_descriptor_t *desc,
+                 sk_read_actor_t recv_actor);
 
 /* UDP uses skb->dev_scratch to cache as much information as possible and avoid
  * possibly multiple cache miss on dequeue()
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index d8c73a848c53..df8e8e238756 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1072,6 +1072,7 @@ const struct proto_ops inet_dgram_ops = {
        .getsockopt        = sock_common_getsockopt,
        .sendmsg           = inet_sendmsg,
        .sendmsg_locked    = udp_sendmsg_locked,
+       .read_sock         = udp_read_sock,
        .recvmsg           = inet_recvmsg,
        .mmap              = sock_no_mmap,
        .sendpage          = inet_sendpage,
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 93db853601d7..54f24b1d4f65 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1798,6 +1798,40 @@ struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned 
int flags,
 }
 EXPORT_SYMBOL(__skb_recv_udp);
 
+int udp_read_sock(struct sock *sk, read_descriptor_t *desc,
+                 sk_read_actor_t recv_actor)
+{
+       int copied = 0;
+
+       while (1) {
+               int offset = 0, err;
+               struct sk_buff *skb;
+
+               skb = __skb_recv_udp(sk, 0, 1, &offset, &err);
+               if (!skb)
+                       break;
+               if (offset < skb->len) {
+                       int used;
+                       size_t len;
+
+                       len = skb->len - offset;
+                       used = recv_actor(desc, skb, offset, len);
+                       if (used <= 0) {
+                               if (!copied)
+                                       copied = used;
+                               break;
+                       } else if (used <= len) {
+                               copied += used;
+                               offset += used;
+                       }
+               }
+               if (!desc->count)
+                       break;
+       }
+
+       return copied;
+}
+
 /*
  *     This should be easy, if there is something there we
  *     return it, otherwise we block.
-- 
2.25.1