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From: Cong Wang <xiyou.wangcong@gmail.com>
To: netdev@vger.kernel.org
Cc: bpf@vger.kernel.org, Cong Wang <cong.wang@bytedance.com>,
	John Fastabend <john.fastabend@gmail.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Jakub Sitnicki <jakub@cloudflare.com>,
	Lorenz Bauer <lmb@cloudflare.com>
Subject: [PATCH bpf-next v5 07/11] af_unix: implement unix_dgram_bpf_recvmsg()
Date: Sun,  4 Jul 2021 12:02:48 -0700	[thread overview]
Message-ID: <20210704190252.11866-8-xiyou.wangcong@gmail.com> (raw)
In-Reply-To: <20210704190252.11866-1-xiyou.wangcong@gmail.com>

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

We have to implement unix_dgram_bpf_recvmsg() to replace the
original ->recvmsg() to retrieve skmsg from ingress_msg.

AF_UNIX is again special here because the lack of
sk_prot->recvmsg(). I simply add a special case inside
unix_dgram_recvmsg() to call sk->sk_prot->recvmsg() directly.

Cc: John Fastabend <john.fastabend@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
---
 include/net/af_unix.h |  2 ++
 net/unix/af_unix.c    | 19 +++++++++--
 net/unix/unix_bpf.c   | 75 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+), 3 deletions(-)

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index cca645846af1..435a2c3d5a6f 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -82,6 +82,8 @@ static inline struct unix_sock *unix_sk(const struct sock *sk)
 long unix_inq_len(struct sock *sk);
 long unix_outq_len(struct sock *sk);
 
+int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
+			 int flags);
 #ifdef CONFIG_SYSCTL
 int unix_sysctl_register(struct net *net);
 void unix_sysctl_unregister(struct net *net);
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 573253c5b5c2..89927678c0dc 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -2098,11 +2098,11 @@ static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
 	}
 }
 
-static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
-			      size_t size, int flags)
+int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
+			 int flags)
 {
 	struct scm_cookie scm;
-	struct sock *sk = sock->sk;
+	struct socket *sock = sk->sk_socket;
 	struct unix_sock *u = unix_sk(sk);
 	struct sk_buff *skb, *last;
 	long timeo;
@@ -2205,6 +2205,19 @@ static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
 	return err;
 }
 
+static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
+			      int flags)
+{
+	struct sock *sk = sock->sk;
+
+#ifdef CONFIG_BPF_SYSCALL
+	if (sk->sk_prot != &unix_proto)
+		return sk->sk_prot->recvmsg(sk, msg, size, flags & MSG_DONTWAIT,
+					    flags & ~MSG_DONTWAIT, NULL);
+#endif
+	return __unix_dgram_recvmsg(sk, msg, size, flags);
+}
+
 static int unix_read_sock(struct sock *sk, read_descriptor_t *desc,
 			  sk_read_actor_t recv_actor)
 {
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
index b1582a659427..db0cda29fb2f 100644
--- a/net/unix/unix_bpf.c
+++ b/net/unix/unix_bpf.c
@@ -6,6 +6,80 @@
 #include <net/sock.h>
 #include <net/af_unix.h>
 
+#define unix_sk_has_data(__sk, __psock)					\
+		({	!skb_queue_empty(&__sk->sk_receive_queue) ||	\
+			!skb_queue_empty(&__psock->ingress_skb) ||	\
+			!list_empty(&__psock->ingress_msg);		\
+		})
+
+static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock,
+			      long timeo)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	struct unix_sock *u = unix_sk(sk);
+	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);
+	if (!unix_sk_has_data(sk, psock)) {
+		mutex_unlock(&u->iolock);
+		wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+		mutex_lock(&u->iolock);
+		ret = unix_sk_has_data(sk, psock);
+	}
+	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	remove_wait_queue(sk_sleep(sk), &wait);
+	return ret;
+}
+
+static int unix_dgram_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
+				  size_t len, int nonblock, int flags,
+				  int *addr_len)
+{
+	struct unix_sock *u = unix_sk(sk);
+	struct sk_psock *psock;
+	int copied, ret;
+
+	psock = sk_psock_get(sk);
+	if (unlikely(!psock))
+		return __unix_dgram_recvmsg(sk, msg, len, flags);
+
+	mutex_lock(&u->iolock);
+	if (!skb_queue_empty(&sk->sk_receive_queue) &&
+	    sk_psock_queue_empty(psock)) {
+		ret = __unix_dgram_recvmsg(sk, msg, len, flags);
+		goto out;
+	}
+
+msg_bytes_ready:
+	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
+	if (!copied) {
+		long timeo;
+		int data;
+
+		timeo = sock_rcvtimeo(sk, nonblock);
+		data = unix_msg_wait_data(sk, psock, timeo);
+		if (data) {
+			if (!sk_psock_queue_empty(psock))
+				goto msg_bytes_ready;
+			ret = __unix_dgram_recvmsg(sk, msg, len, flags);
+			goto out;
+		}
+		copied = -EAGAIN;
+	}
+	ret = copied;
+out:
+	mutex_unlock(&u->iolock);
+	sk_psock_put(sk, psock);
+	return ret;
+}
+
 static struct proto *unix_prot_saved __read_mostly;
 static DEFINE_SPINLOCK(unix_prot_lock);
 static struct proto unix_bpf_prot;
@@ -14,6 +88,7 @@ static void unix_bpf_rebuild_protos(struct proto *prot, const struct proto *base
 {
 	*prot        = *base;
 	prot->close  = sock_map_close;
+	prot->recvmsg = unix_dgram_bpf_recvmsg;
 }
 
 static void unix_bpf_check_needs_rebuild(struct proto *ops)
-- 
2.27.0


  parent reply	other threads:[~2021-07-04 19:03 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-04 19:02 [PATCH bpf-next v5 00/11] sockmap: add sockmap support for unix datagram socket Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 01/11] sock_map: relax config dependency to CONFIG_NET Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 02/11] sock_map: lift socket state restriction for datagram sockets Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 03/11] af_unix: implement ->read_sock() for sockmap Cong Wang
2021-07-12 17:04   ` John Fastabend
2021-07-04 19:02 ` [PATCH bpf-next v5 04/11] af_unix: set TCP_ESTABLISHED for datagram sockets too Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 05/11] af_unix: add a dummy ->close() for sockmap Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 06/11] af_unix: implement ->psock_update_sk_prot() Cong Wang
2021-07-04 19:02 ` Cong Wang [this message]
2021-07-18 17:49   ` [PATCH bpf-next v5 07/11] af_unix: implement unix_dgram_bpf_recvmsg() Eric Dumazet
2021-07-20  0:03     ` Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 08/11] selftests/bpf: factor out udp_socketpair() Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 09/11] selftests/bpf: factor out add_to_sockmap() Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 10/11] selftests/bpf: add a test case for unix sockmap Cong Wang
2021-07-04 19:02 ` [PATCH bpf-next v5 11/11] selftests/bpf: add test cases for redirection between udp and unix Cong Wang
2021-08-05 22:43   ` Andrii Nakryiko
2021-08-06  2:34     ` Cong Wang
2021-07-12 17:02 ` [PATCH bpf-next v5 00/11] sockmap: add sockmap support for unix datagram socket John Fastabend
2021-07-16  1:31   ` Alexei Starovoitov

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