udp: Implement ->read_sock() for sockmap

This is similar to tcp_read_sock(), except we do not need
to worry about connections, we just need to retrieve skb
from UDP receive queue.

Note, the return value of ->read_sock() is unused in
sk_psock_verdict_data_ready(), and UDP still does not
support splice() due to lack of ->splice_read(), so users
can not reach udp_read_sock() directly.

Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210331023237.41094-12-xiyou.wangcong@gmail.com

diff --git a/include/net/udp.h b/include/net/udp.h
index df7cc1edc2002c647469a8f94aa8a42b80baba4f..347b62a753c3a12ec76734c4ec1c6391c776a857 100644 (file)
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -329,6 +329,8 @@ 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 1355e6c0d56777e6b3cd65043496081837b70b3d..f17870ee558bbaa043c10dc5b8a61a3fa1304880 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1070,6 +1070,7 @@ const struct proto_ops inet_dgram_ops = {
        .setsockopt        = sock_common_setsockopt,
        .getsockopt        = sock_common_getsockopt,
        .sendmsg           = inet_sendmsg,
+       .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 38952aaee3a138edd34833a470f76cbf16740840..4d02f6839e381ad9a1129f2ddb03e806e967fbd4 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1782,6 +1782,35 @@ busy_check:
 }
 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) {
+               struct sk_buff *skb;
+               int err, used;
+
+               skb = skb_recv_udp(sk, 0, 1, &err);
+               if (!skb)
+                       return err;
+               used = recv_actor(desc, skb, 0, skb->len);
+               if (used <= 0) {
+                       if (!copied)
+                               copied = used;
+                       break;
+               } else if (used <= skb->len) {
+                       copied += used;
+               }
+
+               if (!desc->count)
+                       break;
+       }
+
+       return copied;
+}
+EXPORT_SYMBOL(udp_read_sock);
+
 /*
  *     This should be easy, if there is something there we
  *     return it, otherwise we block.

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 802f5111805ad0040eacf99fdd8cae4056316a8d..71de739b4a9e475f21eb35f128807ebc7f6c0b7a 100644 (file)
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -714,6 +714,7 @@ const struct proto_ops inet6_dgram_ops = {
        .getsockopt        = sock_common_getsockopt,    /* ok           */
        .sendmsg           = inet6_sendmsg,             /* retpoline's sake */
        .recvmsg           = inet6_recvmsg,             /* retpoline's sake */
+       .read_sock         = udp_read_sock,
        .mmap              = sock_no_mmap,
        .sendpage          = sock_no_sendpage,
        .set_peek_off      = sk_set_peek_off,