From patchwork Wed Apr 8 11:53:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jesper Dangaard Brouer X-Patchwork-Id: 221354 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8A23EC2BA1A for ; Wed, 8 Apr 2020 11:53:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 58BED20780 for ; Wed, 8 Apr 2020 11:53:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RgoyONpl" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728780AbgDHLxP (ORCPT ); Wed, 8 Apr 2020 07:53:15 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:45841 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726901AbgDHLxO (ORCPT ); Wed, 8 Apr 2020 07:53:14 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586346794; 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: in-reply-to:in-reply-to:references:references; bh=pLYh8CDH6AbapdheYhFYc9Jj3Il0ATNizIrBmyTLMXM=; b=RgoyONplrDlmCYZfHkJ0un8Wi2ekuC1ykLiiQf4pdlXKZzGgtvq0vJ+MAv03wbkOYbTGT5 INTU8MABCJY511ktk1UDXNOJxuarTTM08QIByXk39j+ZAmiBVBp3p0qZ3LxJl3hfLJqTdx e03vTYlFBltXgpxcFU1IAEvH3YAuMCA= 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-151-UK65GvVkOkO2fsyJmpUhtg-1; Wed, 08 Apr 2020 07:53:10 -0400 X-MC-Unique: UK65GvVkOkO2fsyJmpUhtg-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 2E61B107ACC4; Wed, 8 Apr 2020 11:53:08 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.40]) by smtp.corp.redhat.com (Postfix) with ESMTP id ADD105D9CA; Wed, 8 Apr 2020 11:53:02 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id BEA28300020FB; Wed, 8 Apr 2020 13:53:01 +0200 (CEST) Subject: [PATCH RFC v2 29/33] xdp: allow bpf_xdp_adjust_tail() to grow packet size From: Jesper Dangaard Brouer To: sameehj@amazon.com Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, bpf@vger.kernel.org, zorik@amazon.com, akiyano@amazon.com, gtzalik@amazon.com, =?utf-8?q?Toke_H=C3=B8iland-J=C3=B8rgensen?= , Daniel Borkmann , Alexei Starovoitov , John Fastabend , Alexander Duyck , Jeff Kirsher , David Ahern , Willem de Bruijn , Ilias Apalodimas , Lorenzo Bianconi , Saeed Mahameed Date: Wed, 08 Apr 2020 13:53:01 +0200 Message-ID: <158634678170.707275.10720666808605360076.stgit@firesoul> In-Reply-To: <158634658714.707275.7903484085370879864.stgit@firesoul> References: <158634658714.707275.7903484085370879864.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Finally, after all drivers have a frame size, allow BPF-helper bpf_xdp_adjust_tail() to grow or extend packet size at frame tail. Remember that helper/macro xdp_data_hard_end have reserved some tailroom. Thus, this helper makes sure that the BPF-prog don't have access to this tailroom area. Signed-off-by: Jesper Dangaard Brouer --- include/uapi/linux/bpf.h | 4 ++-- net/core/filter.c | 18 ++++++++++++++++-- 2 files changed, 18 insertions(+), 4 deletions(-) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 2e29a671d67e..0e5abe991ca3 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1969,8 +1969,8 @@ union bpf_attr { * int bpf_xdp_adjust_tail(struct xdp_buff *xdp_md, int delta) * Description * Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is - * only possible to shrink the packet as of this writing, - * therefore *delta* must be a negative integer. + * possible to both shrink and grow the packet tail. + * Shrink done via *delta* being a negative integer. * * A call to this helper is susceptible to change the underlying * packet buffer. Therefore, at load time, all checks on pointers diff --git a/net/core/filter.c b/net/core/filter.c index 7628b947dbc3..4d58a147eed0 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -3422,12 +3422,26 @@ static const struct bpf_func_proto bpf_xdp_adjust_head_proto = { BPF_CALL_2(bpf_xdp_adjust_tail, struct xdp_buff *, xdp, int, offset) { + void *data_hard_end = xdp_data_hard_end(xdp); void *data_end = xdp->data_end + offset; - /* only shrinking is allowed for now. */ - if (unlikely(offset >= 0)) + /* Notice that xdp_data_hard_end have reserved some tailroom */ + if (unlikely(data_end > data_hard_end)) return -EINVAL; + /* DANGER: ALL drivers MUST be converted to init xdp->frame_sz + * - Adding some chicken checks below + * - Will (likely) not be for upstream + */ + if (unlikely(xdp->frame_sz < (xdp->data_end - xdp->data_hard_start))) { + WARN(1, "Too small xdp->frame_sz = %d\n", xdp->frame_sz); + return -EINVAL; + } + if (unlikely(xdp->frame_sz > PAGE_SIZE)) { + WARN(1, "Too BIG xdp->frame_sz = %d\n", xdp->frame_sz); + return -EINVAL; + } + if (unlikely(data_end < xdp->data + ETH_HLEN)) return -EINVAL;