From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Borkmann Subject: [PATCH bpf 1/3] bpf, sockmap: fix bpf_tcp_sendmsg sock error handling Date: Wed, 8 Aug 2018 19:23:13 +0200 Message-ID: <20180808172315.4710-2-daniel@iogearbox.net> References: <20180808172315.4710-1-daniel@iogearbox.net> Cc: ast@kernel.org, john.fastabend@gmail.com, Daniel Borkmann To: netdev@vger.kernel.org Return-path: Received: from www62.your-server.de ([213.133.104.62]:42638 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727412AbeHHToC (ORCPT ); Wed, 8 Aug 2018 15:44:02 -0400 In-Reply-To: <20180808172315.4710-1-daniel@iogearbox.net> Sender: netdev-owner@vger.kernel.org List-ID: While working on bpf_tcp_sendmsg() code, I noticed that when a sk->sk_err is set we error out with err = sk->sk_err. However this is problematic since sk->sk_err is a positive error value and therefore we will neither go into sk_stream_error() nor will we report an error back to user space. I had this case with EPIPE and user space was thinking sendmsg() succeeded since EPIPE is a positive value, thinking we submitted 32 bytes. Fix it by negating the sk->sk_err value. Fixes: 4f738adba30a ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data") Signed-off-by: Daniel Borkmann Acked-by: John Fastabend --- kernel/bpf/sockmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c index 98fb793..f7360c4 100644 --- a/kernel/bpf/sockmap.c +++ b/kernel/bpf/sockmap.c @@ -1053,7 +1053,7 @@ static int bpf_tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size) int copy; if (sk->sk_err) { - err = sk->sk_err; + err = -sk->sk_err; goto out_err; } -- 2.9.5