From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [216.205.24.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D9A1870 for ; Wed, 26 May 2021 16:04:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1622045093; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=BQRcJTAP6dfxPM101NZlGbovsCjcanY7DSbzlDObwuY=; b=dTU/MMTIV1ls5hX9GO30Og6D1HMETTtCGAT3rpdpQbohcA2ud96rU8ZHCDNNIXrdM+SZqr XiLelVRHyrT7JR2ercd2ZDWbgzW1dzIvQk5ni3HCBnFe39yXs6sIAob4P4KGeTrLxX+Uql 3R47Gg3e4Aqtx0lYdZvTrqdI8Ebi8tI= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-523-Y55UNWyWPqyOPfA9O3GLEw-1; Wed, 26 May 2021 12:04:51 -0400 X-MC-Unique: Y55UNWyWPqyOPfA9O3GLEw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 5E6A6E7B42; Wed, 26 May 2021 16:04:50 +0000 (UTC) Received: from gerbillo.redhat.com (ovpn-113-44.ams2.redhat.com [10.36.113.44]) by smtp.corp.redhat.com (Postfix) with ESMTP id 65D6A5D9CC; Wed, 26 May 2021 16:04:49 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Cc: max@internet.ru Subject: [PATCH mptcp-net] tcp: ensure that backlog coalescing don't break MPTCP DSS Date: Wed, 26 May 2021 18:04:36 +0200 Message-Id: <925dcab4e637ab2ad2d947baa937a62146040802.1622044966.git.pabeni@redhat.com> X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pabeni@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset="US-ASCII" Currently the backlog coalescing does check for MPTCP validation: a relevant DSS could be lost leading to MPTCP stream corruption. The above is quite infrequent since the MPTCP subflows are not exposed to user-space but the MPTCP still acquires the ssk socket lock on some events. Fix the issue adding the missing test. Fixes: 85712484110d ("tcp: coalesce/collapse must respect MPTCP extensions") Signed-off-by: Paolo Abeni --- this can possibly fix issues/196, but it's very hard to demonstrate, even with pktdrill --- net/ipv4/tcp_ipv4.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 4f5b68a90be9..6b033593d069 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1822,6 +1822,7 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb) if (TCP_SKB_CB(tail)->end_seq != TCP_SKB_CB(skb)->seq || TCP_SKB_CB(tail)->ip_dsfield != TCP_SKB_CB(skb)->ip_dsfield || + !mptcp_skb_can_collapse(tail, skb) || ((TCP_SKB_CB(tail)->tcp_flags | TCP_SKB_CB(skb)->tcp_flags) & (TCPHDR_SYN | TCPHDR_RST | TCPHDR_URG)) || !((TCP_SKB_CB(tail)->tcp_flags & -- 2.26.3