bpf, sockmap: Fix data loss caused by using apply_bytes on ingress redirect

[ Upstream commit 9072931f020bfd907d6d89ee21ff1481cd78b407 ]

Use apply_bytes on ingress redirect, when apply_bytes is less than
the length of msg data, some data may be skipped and lost in
bpf_tcp_ingress().

If there is still data in the scatterlist that has not been consumed,
we cannot move the msg iter.

Fixes: 604326b41a6f ("bpf, sockmap: convert to generic sk_msg interface")
Signed-off-by: Pengcheng Yang <yangpc@wangsu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
Link: https://lore.kernel.org/bpf/1669718441-2654-4-git-send-email-yangpc@wangsu.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/tcp_bpf.c b/net/ipv4/tcp_bpf.c
index 275c5ca9e04dfb6294ce7911067a579314f94b95..94aad3870c5fcce9e0140a4547631c50ec49e219 100644 (file)
--- a/net/ipv4/tcp_bpf.c
+++ b/net/ipv4/tcp_bpf.c
@@ -45,8 +45,11 @@ static int bpf_tcp_ingress(struct sock *sk, struct sk_psock *psock,
                tmp->sg.end = i;
                if (apply) {
                        apply_bytes -= size;
-                       if (!apply_bytes)
+                       if (!apply_bytes) {
+                               if (sge->length)
+                                       sk_msg_iter_var_prev(i);
                                break;
+                       }
                }
        } while (i != msg->sg.end);