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authorCong Wang <cong.wang@bytedance.com>2021-06-14 19:13:35 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2021-06-21 16:48:11 +0200
commit9f2470fbc4cb4583c080bb729a998933ba61aca4 (patch)
tree42bfdf373fe8a554dc733cfb558e989e4e8dfae0 /net/ipv4
parent61e8aeda9398925f8c6fc290585bdd9727d154c4 (diff)
downloadlinux-9f2470fbc4cb4583c080bb729a998933ba61aca4.tar.bz2
skmsg: Improve udp_bpf_recvmsg() accuracy
I tried to reuse sk_msg_wait_data() for different protocols, but it turns out it can not be simply reused. For example, UDP actually uses two queues to receive skb: udp_sk(sk)->reader_queue and sk->sk_receive_queue. So we have to check both of them to know whether we have received any packet. Also, UDP does not lock the sock during BH Rx path, it makes no sense for its ->recvmsg() to lock the sock. It is always possible for ->recvmsg() to be called before packets actually arrive in the receive queue, we just use best effort to make it accurate here. Fixes: 1f5be6b3b063 ("udp: Implement udp_bpf_recvmsg() for sockmap") Signed-off-by: Cong Wang <cong.wang@bytedance.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Jakub Sitnicki <jakub@cloudflare.com> Link: https://lore.kernel.org/bpf/20210615021342.7416-2-xiyou.wangcong@gmail.com
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/tcp_bpf.c24
-rw-r--r--net/ipv4/udp_bpf.c47
2 files changed, 65 insertions, 6 deletions
diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index ad9d17923fc5..bb49b52d7be8 100644
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -163,6 +163,28 @@ static bool tcp_bpf_stream_read(const struct sock *sk)
return !empty;
}
+static int tcp_msg_wait_data(struct sock *sk, struct sk_psock *psock, int flags,
+ long timeo, int *err)
+{
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+ int ret = 0;
+
+ if (sk->sk_shutdown & RCV_SHUTDOWN)
+ return 1;
+
+ if (!timeo)
+ return ret;
+
+ add_wait_queue(sk_sleep(sk), &wait);
+ sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ ret = sk_wait_event(sk, &timeo,
+ !list_empty(&psock->ingress_msg) ||
+ !skb_queue_empty(&sk->sk_receive_queue), &wait);
+ sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ remove_wait_queue(sk_sleep(sk), &wait);
+ return ret;
+}
+
static int tcp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
int nonblock, int flags, int *addr_len)
{
@@ -188,7 +210,7 @@ msg_bytes_ready:
long timeo;
timeo = sock_rcvtimeo(sk, nonblock);
- data = sk_msg_wait_data(sk, psock, flags, timeo, &err);
+ data = tcp_msg_wait_data(sk, psock, flags, timeo, &err);
if (data) {
if (!sk_psock_queue_empty(psock))
goto msg_bytes_ready;
diff --git a/net/ipv4/udp_bpf.c b/net/ipv4/udp_bpf.c
index 954c4591a6fd..565a70040c57 100644
--- a/net/ipv4/udp_bpf.c
+++ b/net/ipv4/udp_bpf.c
@@ -21,6 +21,45 @@ static int sk_udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
return udp_prot.recvmsg(sk, msg, len, noblock, flags, addr_len);
}
+static bool udp_sk_has_data(struct sock *sk)
+{
+ return !skb_queue_empty(&udp_sk(sk)->reader_queue) ||
+ !skb_queue_empty(&sk->sk_receive_queue);
+}
+
+static bool psock_has_data(struct sk_psock *psock)
+{
+ return !skb_queue_empty(&psock->ingress_skb) ||
+ !sk_psock_queue_empty(psock);
+}
+
+#define udp_msg_has_data(__sk, __psock) \
+ ({ udp_sk_has_data(__sk) || psock_has_data(__psock); })
+
+static int udp_msg_wait_data(struct sock *sk, struct sk_psock *psock, int flags,
+ long timeo, int *err)
+{
+ DEFINE_WAIT_FUNC(wait, woken_wake_function);
+ int ret = 0;
+
+ if (sk->sk_shutdown & RCV_SHUTDOWN)
+ return 1;
+
+ if (!timeo)
+ return ret;
+
+ add_wait_queue(sk_sleep(sk), &wait);
+ sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ ret = udp_msg_has_data(sk, psock);
+ if (!ret) {
+ wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+ ret = udp_msg_has_data(sk, psock);
+ }
+ sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+ remove_wait_queue(sk_sleep(sk), &wait);
+ return ret;
+}
+
static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
int nonblock, int flags, int *addr_len)
{
@@ -34,8 +73,7 @@ static int udp_bpf_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
if (unlikely(!psock))
return sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
- lock_sock(sk);
- if (sk_psock_queue_empty(psock)) {
+ if (!psock_has_data(psock)) {
ret = sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
goto out;
}
@@ -47,9 +85,9 @@ msg_bytes_ready:
long timeo;
timeo = sock_rcvtimeo(sk, nonblock);
- data = sk_msg_wait_data(sk, psock, flags, timeo, &err);
+ data = udp_msg_wait_data(sk, psock, flags, timeo, &err);
if (data) {
- if (!sk_psock_queue_empty(psock))
+ if (psock_has_data(psock))
goto msg_bytes_ready;
ret = sk_udp_recvmsg(sk, msg, len, nonblock, flags, addr_len);
goto out;
@@ -62,7 +100,6 @@ msg_bytes_ready:
}
ret = copied;
out:
- release_sock(sk);
sk_psock_put(sk, psock);
return ret;
}