From patchwork Tue Mar 17 17:30:03 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: 222378 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 9C973C5ACD6 for ; Tue, 17 Mar 2020 17:30:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 74C7B20724 for ; Tue, 17 Mar 2020 17:30:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="cpNGEMYp" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726851AbgCQRaV (ORCPT ); Tue, 17 Mar 2020 13:30:21 -0400 Received: from us-smtp-delivery-74.mimecast.com ([216.205.24.74]:53390 "EHLO us-smtp-delivery-74.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726647AbgCQRaV (ORCPT ); Tue, 17 Mar 2020 13:30:21 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1584466219; 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=cpNGEMYpFryqIs7iDVOGhP4KrJvGRgynyB6weIcivNEYeRPOjzqG9f+YHNWoGVmK2YaqUw oQq4fAlhRPOzsbrLdyN8vpr5ju27O5CaKhXEcf08xh0mRkAXK7lfckZSP7sWwcSvN52YbO Zi1eK/KrlbA3z+S54+ge4QqrQauWPaM= 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-177-oNsI659-Nsu79eluQ9RN-A-1; Tue, 17 Mar 2020 13:30:15 -0400 X-MC-Unique: oNsI659-Nsu79eluQ9RN-A-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 25AAF8018B6; Tue, 17 Mar 2020 17:30:05 +0000 (UTC) Received: from firesoul.localdomain (unknown [10.40.208.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id ACB6760BEE; Tue, 17 Mar 2020 17:30:04 +0000 (UTC) Received: from [192.168.42.3] (localhost [IPv6:::1]) by firesoul.localdomain (Postfix) with ESMTP id A7E0030721A66; Tue, 17 Mar 2020 18:30:03 +0100 (CET) Subject: [PATCH RFC v1 11/15] 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 Date: Tue, 17 Mar 2020 18:30:03 +0100 Message-ID: <158446620361.702578.11853795393121537634.stgit@firesoul> In-Reply-To: <158446612466.702578.2795159620575737080.stgit@firesoul> References: <158446612466.702578.2795159620575737080.stgit@firesoul> User-Agent: StGit/0.19 MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@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);