From: Sabrina Dubroca Date: Wed, 10 Jun 2020 10:19:43 +0000 (+0200) Subject: bpf: tcp: Recv() should return 0 when the peer socket is closed X-Git-Tag: v5.7.6~365 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=5cc720f10234d456ad3273912415d928647c681d;p=users%2Fdwmw2%2Flinux.git bpf: tcp: Recv() should return 0 when the peer socket is closed [ Upstream commit 2c7269b231194aae23fb90ab65842573a91acbc9 ] If the peer is closed, we will never get more data, so tcp_bpf_wait_data will get stuck forever. In case we passed MSG_DONTWAIT to recv(), we get EAGAIN but we should actually get 0. >From man 2 recv: RETURN VALUE When a stream socket peer has performed an orderly shutdown, the return value will be 0 (the traditional "end-of-file" return). This patch makes tcp_bpf_wait_data always return 1 when the peer socket has been shutdown. Either we have data available, and it would have returned 1 anyway, or there isn't, in which case we'll call tcp_recvmsg which does the right thing in this situation. Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface") Signed-off-by: Sabrina Dubroca Signed-off-by: Alexei Starovoitov Acked-by: Jakub Sitnicki Link: https://lore.kernel.org/bpf/26038a28c21fea5d04d4bd4744c5686d3f2e5504.1591784177.git.sd@queasysnail.net Signed-off-by: Sasha Levin --- diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c index 629aaa9a1eb99..9c5540887fbe5 100644 --- a/net/ipv4/tcp_bpf.c +++ b/net/ipv4/tcp_bpf.c @@ -242,6 +242,9 @@ static int tcp_bpf_wait_data(struct sock *sk, struct sk_psock *psock, DEFINE_WAIT_FUNC(wait, woken_wake_function); int ret = 0; + if (sk->sk_shutdown & RCV_SHUTDOWN) + return 1; + if (!timeo) return ret;