From: Cong Wang <cong.wang@xxxxxxxxxxxxx>
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.
Cc: John Fastabend <john.fastabend@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Jakub Sitnicki <jakub@xxxxxxxxxxxxxx>
Cc: Lorenz Bauer <lmb@xxxxxxxxxxxxxx>
Signed-off-by: Cong Wang <cong.wang@xxxxxxxxxxxxx>
---
include/net/udp.h | 2 ++
net/ipv4/af_inet.c | 1 +
net/ipv4/udp.c | 29 +++++++++++++++++++++++++++++
net/ipv6/af_inet6.c | 1 +
4 files changed, 33 insertions(+)
diff --git a/include/net/udp.h b/include/net/udp.h
index df7cc1edc200..347b62a753c3 100644
--- 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 1355e6c0d567..f17870ee558b 100644
--- 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 38952aaee3a1..4d02f6839e38 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1782,6 +1782,35 @@ 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) {
+ 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 802f5111805a..71de739b4a9e 100644
--- 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,
--
2.25.1
