Commit 5121700b authored Aug 08, 2018 by Daniel Borkmann Committed by Alexei Starovoitov Aug 08, 2018

bpf, sockmap: fix bpf_tcp_sendmsg sock error handling



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: 4f738adb ("bpf: create tcp_bpf_ulp allowing BPF to monitor socket TX/RX data")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

parent 74682128

kernel/bpf/sockmap.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -1053,7 +1053,7 @@ static int bpf_tcp_sendmsg(struct sock sk, struct msghdr msg, size_t size)
	int copy;		int copy;

	if (sk->sk_err) {		if (sk->sk_err) {
	err = sk->sk_err;		err = -sk->sk_err;
	goto out_err;		goto out_err;
	}		}

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