From patchwork Wed Oct 11 15:23:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Abeni X-Patchwork-Id: 13417558 X-Patchwork-Delegate: matthieu.baerts@tessares.net Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 2AE891F18A for ; Wed, 11 Oct 2023 15:23:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UEe416sA" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1697037823; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=2tzKJKmmiHgpmcwwc5VDA2d6SZCk2lq2AEu1KZ7V8Ec=; b=UEe416sAuu85V1gsN6PyveiKMaMuvk2HJ0QPpuJ2VUk15yABspBV32n1THV2iXWL+fhvsk HvWSL2ATufL+FY2LQBetZOYYwfKBGXombx3IcZQsywGvxWWE09orPrBGs4Qa9pd+aWrqeG S73V+LSI7PYT2+uyuyQJuRcgPFVKQzM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-247-8zfdfu8MMh2KFl_qlzmVKw-1; Wed, 11 Oct 2023 11:23:42 -0400 X-MC-Unique: 8zfdfu8MMh2KFl_qlzmVKw-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 59EFA86893E for ; Wed, 11 Oct 2023 15:23:35 +0000 (UTC) Received: from gerbillo.redhat.com (unknown [10.45.225.21]) by smtp.corp.redhat.com (Postfix) with ESMTP id DB9F5492B04 for ; Wed, 11 Oct 2023 15:23:34 +0000 (UTC) From: Paolo Abeni To: mptcp@lists.linux.dev Subject: [PATCH mptcp-net v2] tcp: check mptcp-level constraints for backlog coalescing Date: Wed, 11 Oct 2023 17:23:13 +0200 Message-ID: Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com The MPTCP protocol can acquire the subflow-level socket lock and cause the tcp backlog usage. When inserting new skbs into the backlog, the stack will try to coalesce them. Currently, we have no check in place to ensure that such coalescing will respect the MPTCP-level DSS, and that may cause data stream corruption, as reported by Christoph. Address the issue by adding the relevant admission check for coalescing in tcp_add_backlog(). Note the issue is not easy to reproduce, as the MPTCP protocol tries hard to avoid acquiring the subflow-level socket lock. Fixes: 648ef4b88673 ("mptcp: Implement MPTCP receive path") Reported-by: Christoph Paasch Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/420 Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau --- v1 -> v2: - !coalesce (mat) - typo in commit message (mat) --- 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 a441740616d7..4d66a8ab3b98 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1870,6 +1870,7 @@ bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb, #ifdef CONFIG_TLS_DEVICE tail->decrypted != skb->decrypted || #endif + !mptcp_skb_can_collapse(tail, skb) || thtail->doff != th->doff || memcmp(thtail + 1, th + 1, hdrlen - sizeof(*th))) goto no_coalesce;