From patchwork Tue Feb 24 17:17:31 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tom Herbert X-Patchwork-Id: 443074 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 043D6140146 for ; Wed, 25 Feb 2015 04:17:54 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753255AbbBXRRu (ORCPT ); Tue, 24 Feb 2015 12:17:50 -0500 Received: from mail-ie0-f171.google.com ([209.85.223.171]:32968 "EHLO mail-ie0-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752991AbbBXRRs (ORCPT ); Tue, 24 Feb 2015 12:17:48 -0500 Received: by iecar1 with SMTP id ar1so33933037iec.0 for ; Tue, 24 Feb 2015 09:17:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=from:to:subject:date:message-id; bh=S+trB8tRStMV2rbs96l+wT9m/EHmWvVdJQmArkWFqSk=; b=ZlBjoD6btZ3++BZFcHhzBqGTY4N5k+vAztegFwKzZDvh+QFaoF5+Np3Xf95Arue+Qg Czv/jP0n4J6r1A52qQAXJG+j8kkRXAI10iP0Di7eDV4KNdEFk/p7df2/6dP5dSUctlnf 7JaVkDZzCt8QC/aM4nIZRgjyxns3Up7HiJWqCiii40xBmPwaCFw4wFRPseVDGFdiJXXQ D23eDMM+LddtGQomRoUOIEwsHoscxPAoMsnyfP8BzyQ5j3NFsrNYSlUZo+fYR8seN2YP I4SuIBHsqgtQMgoQZeFvGF1wzAxxjtVq4NDXMCfdz+zwtm0F6EVHgSAofBtFb4VneOBj STVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:subject:date:message-id; bh=S+trB8tRStMV2rbs96l+wT9m/EHmWvVdJQmArkWFqSk=; b=dhKuhAStLGaiEkEiz+Cpg7njGbeuA3OBqp7FSeB2lIcJGMNA6XwFD2iF1f25tDPYjO x0Bw1DU/yxCaUuZcbAm4k8x+X6BNUnrHXxX/AK1RwYERbOUz5FhzMQ0YG3Raw+CtJJLO bpENI4hJ0Znlz0MWH4dLI1bzcO1+FkRVQMuUYVoF/6ZIqBQdPFHL707XHSG70RB8x3wJ L0ZoDgy1bYlQ1Q2kxoSBw47JvgwN9OHE6MhF2VU/3lhJk2awEm2iTMuhT1Lall7emLts gLxdbbb1n0wId1Xc5W7ozImg2iLMizlD132sla5NtniSBGUDK+khu3pXaVe2mE7ctAkL sLcg== X-Gm-Message-State: ALoCoQks2LXjEbuCl9noOkJWSA0C/qLqGKft4cjCsoiwyeJCCjIFBV44iUafXJP5+fyEPyZJkYUr X-Received: by 10.50.109.228 with SMTP id hv4mr21694435igb.45.1424798268070; Tue, 24 Feb 2015 09:17:48 -0800 (PST) Received: from tomh.mtv.corp.google.com ([172.18.117.126]) by mx.google.com with ESMTPSA id ht8sm8282452igb.0.2015.02.24.09.17.46 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 24 Feb 2015 09:17:47 -0800 (PST) From: Tom Herbert To: davem@davemloft.net, netdev@vger.kernel.org Subject: [PATCH net-next] udp: In udp_flow_src_port use random hash value if skb_get_hash fails Date: Tue, 24 Feb 2015 09:17:31 -0800 Message-Id: <1424798251-21075-1-git-send-email-therbert@google.com> X-Mailer: git-send-email 2.2.0.rc0.207.ga3a616c Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org In the unlikely event that skb_get_hash is unable to deduce a hash in udp_flow_src_port we use a consistent random value instead. This is specified in GRE/UDP draft section 3.2.1: https://tools.ietf.org/html/draft-ietf-tsvwg-gre-in-udp-encap-04 Signed-off-by: Tom Herbert --- include/net/udp.h | 21 +++++++++++++++------ net/ipv4/udp.c | 10 ++++++++++ 2 files changed, 25 insertions(+), 6 deletions(-) diff --git a/include/net/udp.h b/include/net/udp.h index 07f9b70..32d8d9f 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -194,6 +194,8 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, int (*)(const struct sock *, const struct sock *), unsigned int hash2_nulladdr); +u32 udp_flow_hashrnd(void); + static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb, int min, int max, bool use_eth) { @@ -205,12 +207,19 @@ static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb, } hash = skb_get_hash(skb); - if (unlikely(!hash) && use_eth) { - /* Can't find a normal hash, caller has indicated an Ethernet - * packet so use that to compute a hash. - */ - hash = jhash(skb->data, 2 * ETH_ALEN, - (__force u32) skb->protocol); + if (unlikely(!hash)) { + if (use_eth) { + /* Can't find a normal hash, caller has indicated an + * Ethernet packet so use that to compute a hash. + */ + hash = jhash(skb->data, 2 * ETH_ALEN, + (__force u32) skb->protocol); + } else { + /* Can't derive any sort of hash for the packet, set + * to some consistent random value. + */ + hash = udp_flow_hashrnd(); + } } /* Since this is being sent on the wire obfuscate hash a bit diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 97ef1f8b..0224f93 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -2525,6 +2525,16 @@ void __init udp_table_init(struct udp_table *table, const char *name) } } +u32 udp_flow_hashrnd(void) +{ + static u32 hashrnd __read_mostly; + + net_get_random_once(&hashrnd, sizeof(hashrnd)); + + return hashrnd; +} +EXPORT_SYMBOL(udp_flow_hashrnd); + void __init udp_init(void) { unsigned long limit;