The patch below does not apply to the 5.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 31bf11de146c3f8892093ff39f8f9b3069d6a852 Mon Sep 17 00:00:00 2001 From: Paolo Abeni pabeni@redhat.com Date: Mon, 27 Jun 2022 18:02:36 -0700 Subject: [PATCH] mptcp: introduce MAPPING_BAD_CSUM

This allow moving a couple of conditional out of the fast path, making the code more easy to follow and will simplify the next patch.

Fixes: ae66fb2ba6c3 ("mptcp: Do TCP fallback on early DSS checksum failure") Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Mat Martineau mathew.j.martineau@linux.intel.com Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 50ad19adc003..42a7c18a1c24 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -843,7 +843,8 @@ enum mapping_status { MAPPING_INVALID, MAPPING_EMPTY, MAPPING_DATA_FIN, - MAPPING_DUMMY + MAPPING_DUMMY, + MAPPING_BAD_CSUM };

static void dbg_bad_map(struct mptcp_subflow_context *subflow, u32 ssn) @@ -958,9 +959,7 @@ static enum mapping_status validate_data_csum(struct sock *ssk, struct sk_buff * subflow->map_data_csum); if (unlikely(csum)) { MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_DATACSUMERR); - if (subflow->mp_join || subflow->valid_csum_seen) - subflow->send_mp_fail = 1; - return subflow->mp_join ? MAPPING_INVALID : MAPPING_DUMMY; + return MAPPING_BAD_CSUM; }

subflow->valid_csum_seen = 1; @@ -1182,10 +1181,8 @@ static bool subflow_check_data_avail(struct sock *ssk)

status = get_mapping_status(ssk, msk); trace_subflow_check_data_avail(status, skb_peek(&ssk->sk_receive_queue)); - if (unlikely(status == MAPPING_INVALID)) - goto fallback; - - if (unlikely(status == MAPPING_DUMMY)) + if (unlikely(status == MAPPING_INVALID || status == MAPPING_DUMMY || + status == MAPPING_BAD_CSUM)) goto fallback;

if (status != MAPPING_OK) @@ -1227,7 +1224,10 @@ static bool subflow_check_data_avail(struct sock *ssk) fallback: if (!__mptcp_check_fallback(msk)) { /* RFC 8684 section 3.7. */ - if (subflow->send_mp_fail) { + if (status == MAPPING_BAD_CSUM && + (subflow->mp_join || subflow->valid_csum_seen)) { + subflow->send_mp_fail = 1; + if (!READ_ONCE(msk->allow_infinite_fallback)) { ssk->sk_err = EBADMSG; tcp_set_state(ssk, TCP_CLOSE);