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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 B754EC49ED7 for ; Mon, 28 Jun 2021 15:28:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9E90D61C3D for ; Mon, 28 Jun 2021 15:28:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238992AbhF1Paw (ORCPT ); Mon, 28 Jun 2021 11:30:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:39694 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237266AbhF1PFa (ORCPT ); Mon, 28 Jun 2021 11:05:30 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 5427561D78; Mon, 28 Jun 2021 14:43:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624891414; bh=2MDYhbIpIajyZKl3tZj73AoVdKemhylQkE+zODFupNk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=t7VP08+EbWHvn6ppQipmVaJPM6F0F9a/zCXL+gcQLSRNwpSdpKdBxTsfMGIa4h85M wx3QWRYSv0Fmb5H4CrJkXeArLBXZEViXZMBPL6t2J8ROnZ4HBInIjemeB7td4ldyUO mHcwKEqzTj3XNQ1AGYlE1F3dX/ibFWhCzRIeXOCN23fNyMZvxw98g5vdAQ/LdNBqTi XiF0CrUOhjorrpZmkwWuuEwq3HcDg8Qu84H5eClJZXKEDRGKCDYPb8u8OBLCpGGFyn ezBHhtD8nlHAn//NZEFzzAyuqBBxZ0No+JHCV1S6LSSkdi7qNYvF600ubD4ChoaGyP nAgMMl06Pa3sg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Dumazet , Amit Klein , Willy Tarreau , "David S . Miller" , Greg Kroah-Hartman Subject: [PATCH 4.4 42/57] inet: use bigger hash table for IP ID generation Date: Mon, 28 Jun 2021 10:42:41 -0400 Message-Id: <20210628144256.34524-43-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210628144256.34524-1-sashal@kernel.org> References: <20210628144256.34524-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v4.x/stable-review/patch-4.4.274-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-4.4.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 4.4.274-rc1 X-KernelTest-Deadline: 2021-06-30T14:42+00:00 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet commit aa6dd211e4b1dde9d5dc25d699d35f789ae7eeba upstream. In commit 73f156a6e8c1 ("inetpeer: get rid of ip_id_count") I used a very small hash table that could be abused by patient attackers to reveal sensitive information. Switch to a dynamic sizing, depending on RAM size. Typical big hosts will now use 128x more storage (2 MB) to get a similar increase in security and reduction of hash collisions. As a bonus, use of alloc_large_system_hash() spreads allocated memory among all NUMA nodes. Fixes: 73f156a6e8c1 ("inetpeer: get rid of ip_id_count") Reported-by: Amit Klein Signed-off-by: Eric Dumazet Cc: Willy Tarreau Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/route.c | 42 +++++++++++++++++++++++++++++------------- 1 file changed, 29 insertions(+), 13 deletions(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index ea1c319100a5..2ab2289d97a0 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -70,6 +70,7 @@ #include #include #include +#include #include #include #include @@ -463,8 +464,10 @@ static struct neighbour *ipv4_neigh_lookup(const struct dst_entry *dst, return neigh_create(&arp_tbl, pkey, dev); } -#define IP_IDENTS_SZ 2048u - +/* Hash tables of size 2048..262144 depending on RAM size. + * Each bucket uses 8 bytes. + */ +static u32 ip_idents_mask __read_mostly; static atomic_t *ip_idents __read_mostly; static u32 *ip_tstamps __read_mostly; @@ -474,12 +477,16 @@ static u32 *ip_tstamps __read_mostly; */ u32 ip_idents_reserve(u32 hash, int segs) { - u32 *p_tstamp = ip_tstamps + hash % IP_IDENTS_SZ; - atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ; - u32 old = ACCESS_ONCE(*p_tstamp); - u32 now = (u32)jiffies; + u32 bucket, old, now = (u32)jiffies; + atomic_t *p_id; + u32 *p_tstamp; u32 delta = 0; + bucket = hash & ip_idents_mask; + p_tstamp = ip_tstamps + bucket; + p_id = ip_idents + bucket; + old = ACCESS_ONCE(*p_tstamp); + if (old != now && cmpxchg(p_tstamp, old, now) == old) delta = prandom_u32_max(now - old); @@ -2936,18 +2943,27 @@ struct ip_rt_acct __percpu *ip_rt_acct __read_mostly; int __init ip_rt_init(void) { + void *idents_hash; int rc = 0; int cpu; - ip_idents = kmalloc(IP_IDENTS_SZ * sizeof(*ip_idents), GFP_KERNEL); - if (!ip_idents) - panic("IP: failed to allocate ip_idents\n"); + /* For modern hosts, this will use 2 MB of memory */ + idents_hash = alloc_large_system_hash("IP idents", + sizeof(*ip_idents) + sizeof(*ip_tstamps), + 0, + 16, /* one bucket per 64 KB */ + 0, + NULL, + &ip_idents_mask, + 2048, + 256*1024); + + ip_idents = idents_hash; - prandom_bytes(ip_idents, IP_IDENTS_SZ * sizeof(*ip_idents)); + prandom_bytes(ip_idents, (ip_idents_mask + 1) * sizeof(*ip_idents)); - ip_tstamps = kcalloc(IP_IDENTS_SZ, sizeof(*ip_tstamps), GFP_KERNEL); - if (!ip_tstamps) - panic("IP: failed to allocate ip_tstamps\n"); + ip_tstamps = idents_hash + (ip_idents_mask + 1) * sizeof(*ip_idents); + memset(ip_tstamps, 0, (ip_idents_mask + 1) * sizeof(*ip_tstamps)); for_each_possible_cpu(cpu) { struct uncached_list *ul = &per_cpu(rt_uncached_list, cpu); -- 2.30.2