From mboxrd@z Thu Jan 1 00:00:00 1970 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=ham 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 D0311C2BA1A for ; Wed, 8 Apr 2020 11:51:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A38D420780 for ; Wed, 8 Apr 2020 11:51:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="EN51ivSC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728654AbgDHLvS (ORCPT ); Wed, 8 Apr 2020 07:51:18 -0400 Received: from us-smtp-2.mimecast.com ([205.139.110.61]:45805 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728647AbgDHLvS (ORCPT ); Wed, 8 Apr 2020 07:51:18 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586346677; 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=NDjKx6IwnF/NmrEYCxfuH2dwTT6/S8zsEJsWIeaXprg=; b=EN51ivSCtI5EW4wxF5ss9MrvHvtzkSHddbV7kLlfwL0SmGqu+f4kb6nhBznOEppks2h2MB yzaGikmA0PrlRk1SNAduBdCwCtO2R8MqwQ1CKZcnhAJ5LysECcP68hN7B4CoWnHR81cjx5 OAu/HrEKZpDYOlUZWIaBiQ8b8qj/wdM= 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-246-abD4zobdP5eA8qu5LJhn0Q-1; Wed, 08 Apr 2020 07:51:13 -0400 X-MC-Unique: abD4zobdP5eA8qu5LJhn0Q-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 396AE100DFC9; Wed, 8 Apr 2020 11:51:11 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.40]) by smtp.corp.redhat.com (Postfix) with ESMTP id D88E85C28F; Wed, 8 Apr 2020 11:51:10 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id E5283300020FC; Wed, 8 Apr 2020 13:51:09 +0200 (CEST) Subject: [PATCH RFC v2 07/33] xdp: xdp_frame add member frame_sz and handle in convert_to_xdp_frame 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 13:51:09 +0200 Message-ID: <158634666986.707275.3125872827455406207.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 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org Use hole in struct xdp_frame, when adding member frame_sz, which keeps same sizeof struct (32 bytes) Drivers ixgbe and sfc had bug cases where the necessary/expected tailroom was not reserved. This can lead to some hard to catch memory corruption issues. Having the drivers frame_sz this can be detected when packet length/end via xdp->data_end exceed the xdp_data_hard_end pointer, which accounts for the reserved the tailroom. When detecting this driver issue, simply fail the conversion with NULL, which results in feedback to driver (failing xdp_do_redirect()) causing driver to drop packet. Given the lack of consistent XDP stats, this can be hard to troubleshoot. And given this is a driver bug, we want to generate some more noise in form of a WARN stack dump (to ID the driver code that inlined convert_to_xdp_frame). Inlining the WARN macro is problematic, because it adds an asm instruction (on Intel CPUs ud2) what influence instruction cache prefetching. Thus, introduce xdp_warn and macro XDP_WARN, to avoid this and at the same time make identifying the function and line of this inlined function easier. Signed-off-by: Jesper Dangaard Brouer --- include/net/xdp.h | 14 +++++++++++++- net/core/xdp.c | 7 +++++++ 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/include/net/xdp.h b/include/net/xdp.h index 99f4374f6214..55a885aa4e53 100644 --- a/include/net/xdp.h +++ b/include/net/xdp.h @@ -93,7 +93,8 @@ struct xdp_frame { void *data; u16 len; u16 headroom; - u16 metasize; + u32 metasize:8; + u32 frame_sz:24; /* Lifetime of xdp_rxq_info is limited to NAPI/enqueue time, * while mem info is valid on remote CPU. */ @@ -108,6 +109,10 @@ static inline void xdp_scrub_frame(struct xdp_frame *frame) frame->dev_rx = NULL; } +/* Avoids inlining WARN macro in fast-path */ +void xdp_warn(const char* msg, const char* func, const int line); +#define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__) + struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp); /* Convert xdp_buff to xdp_frame */ @@ -128,6 +133,12 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp) if (unlikely((headroom - metasize) < sizeof(*xdp_frame))) return NULL; + /* Catch if driver didn't reserve tailroom for skb_shared_info */ + if (unlikely(xdp->data_end > xdp_data_hard_end(xdp))) { + XDP_WARN("Driver BUG: missing reserved tailroom"); + return NULL; + } + /* Store info in top of packet */ xdp_frame = xdp->data_hard_start; @@ -135,6 +146,7 @@ struct xdp_frame *convert_to_xdp_frame(struct xdp_buff *xdp) xdp_frame->len = xdp->data_end - xdp->data; xdp_frame->headroom = headroom - sizeof(*xdp_frame); xdp_frame->metasize = metasize; + xdp_frame->frame_sz = xdp->frame_sz; /* rxq only valid until napi_schedule ends, convert to xdp_mem_info */ xdp_frame->mem = xdp->rxq->mem; diff --git a/net/core/xdp.c b/net/core/xdp.c index 4c7ea85486af..4bc3026ae218 100644 --- a/net/core/xdp.c +++ b/net/core/xdp.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include @@ -496,3 +497,9 @@ struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp) return xdpf; } EXPORT_SYMBOL_GPL(xdp_convert_zc_to_xdp_frame); + +/* Used by XDP_WARN macro, to avoid inlining WARN() in fast-path */ +void xdp_warn(const char* msg, const char* func, const int line) { + WARN(1, "XDP_WARN: %s(line:%d): %s\n", func, line, msg); +}; +EXPORT_SYMBOL_GPL(xdp_warn);