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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,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 D26BFFA372C for ; Fri, 8 Nov 2019 19:16:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9D2C520650 for ; Fri, 8 Nov 2019 19:16:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573240565; bh=wiH+irj//p+qJgDw6BWeSlXmeKrC5A3XHnPhOweIn3Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Pdys/rFJZcnEfWBYHVqXe4+tObSY2Ay8rTZy9uwbK3ylCZQwqmqsyKc4qkQgiJoLE VC+g/ZOLKcgvbrfxdlYXuCPnXzZ5w8FZtUOvo190LYQbE4z2ixZJH61D7jmdkPBZR2 Kgkzban32nflAlTHgIwVpzRcUfU0kf8BH9Z29RbU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389024AbfKHTDn (ORCPT ); Fri, 8 Nov 2019 14:03:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:33476 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732439AbfKHTDn (ORCPT ); Fri, 8 Nov 2019 14:03:43 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C17082067B; Fri, 8 Nov 2019 19:03:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573239822; bh=wiH+irj//p+qJgDw6BWeSlXmeKrC5A3XHnPhOweIn3Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ujK8WJtbktVE0Wc28VuzuDwYl5E9ip1yhqLFlnX7oOfpY2luKxv8TUDQrp9pl3ZVA YN+dJtzt8hjH02Y4b69NdJgS8/GkaIACqXae7UcQIOgc52a3zgwD/bLXAr50gStFmP IOZGcojF+nDpg2vT+M1PEj/VpQlNtIeiCSP/xyVI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Jonathan Berger , Amit Klein , Benny Pinkas , Tom Herbert , "David S. Miller" Subject: [PATCH 4.19 71/79] net/flow_dissector: switch to siphash Date: Fri, 8 Nov 2019 19:50:51 +0100 Message-Id: <20191108174824.523533212@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191108174745.495640141@linuxfoundation.org> References: <20191108174745.495640141@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit 55667441c84fa5e0911a0aac44fb059c15ba6da2 ] UDP IPv6 packets auto flowlabels are using a 32bit secret (static u32 hashrnd in net/core/flow_dissector.c) and apply jhash() over fields known by the receivers. Attackers can easily infer the 32bit secret and use this information to identify a device and/or user, since this 32bit secret is only set at boot time. Really, using jhash() to generate cookies sent on the wire is a serious security concern. Trying to change the rol32(hash, 16) in ip6_make_flowlabel() would be a dead end. Trying to periodically change the secret (like in sch_sfq.c) could change paths taken in the network for long lived flows. Let's switch to siphash, as we did in commit df453700e8d8 ("inet: switch IP ID generator to siphash") Using a cryptographically strong pseudo random function will solve this privacy issue and more generally remove other weak points in the stack. Packet schedulers using skb_get_hash_perturb() benefit from this change. Fixes: b56774163f99 ("ipv6: Enable auto flow labels by default") Fixes: 42240901f7c4 ("ipv6: Implement different admin modes for automatic flow labels") Fixes: 67800f9b1f4e ("ipv6: Call skb_get_hash_flowi6 to get skb->hash in ip6_make_flowlabel") Fixes: cb1ce2ef387b ("ipv6: Implement automatic flow label generation on transmit") Signed-off-by: Eric Dumazet Reported-by: Jonathan Berger Reported-by: Amit Klein Reported-by: Benny Pinkas Cc: Tom Herbert Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 3 ++- include/net/flow_dissector.h | 3 ++- include/net/fq.h | 2 +- include/net/fq_impl.h | 4 ++-- net/core/flow_dissector.c | 38 ++++++++++++++++---------------------- net/sched/sch_hhf.c | 8 ++++---- net/sched/sch_sfb.c | 13 +++++++------ net/sched/sch_sfq.c | 14 ++++++++------ 8 files changed, 42 insertions(+), 43 deletions(-) --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -1251,7 +1251,8 @@ static inline __u32 skb_get_hash_flowi6( return skb->hash; } -__u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb); +__u32 skb_get_hash_perturb(const struct sk_buff *skb, + const siphash_key_t *perturb); static inline __u32 skb_get_hash_raw(const struct sk_buff *skb) { --- a/include/net/flow_dissector.h +++ b/include/net/flow_dissector.h @@ -4,6 +4,7 @@ #include #include +#include #include /** @@ -252,7 +253,7 @@ struct flow_keys_basic { struct flow_keys { struct flow_dissector_key_control control; #define FLOW_KEYS_HASH_START_FIELD basic - struct flow_dissector_key_basic basic; + struct flow_dissector_key_basic basic __aligned(SIPHASH_ALIGNMENT); struct flow_dissector_key_tags tags; struct flow_dissector_key_vlan vlan; struct flow_dissector_key_vlan cvlan; --- a/include/net/fq.h +++ b/include/net/fq.h @@ -70,7 +70,7 @@ struct fq { struct list_head backlogs; spinlock_t lock; u32 flows_cnt; - u32 perturbation; + siphash_key_t perturbation; u32 limit; u32 memory_limit; u32 memory_usage; --- a/include/net/fq_impl.h +++ b/include/net/fq_impl.h @@ -118,7 +118,7 @@ static struct fq_flow *fq_flow_classify( lockdep_assert_held(&fq->lock); - hash = skb_get_hash_perturb(skb, fq->perturbation); + hash = skb_get_hash_perturb(skb, &fq->perturbation); idx = reciprocal_scale(hash, fq->flows_cnt); flow = &fq->flows[idx]; @@ -307,7 +307,7 @@ static int fq_init(struct fq *fq, int fl INIT_LIST_HEAD(&fq->backlogs); spin_lock_init(&fq->lock); fq->flows_cnt = max_t(u32, flows_cnt, 1); - fq->perturbation = prandom_u32(); + get_random_bytes(&fq->perturbation, sizeof(fq->perturbation)); fq->quantum = 300; fq->limit = 8192; fq->memory_limit = 16 << 20; /* 16 MBytes */ --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -1077,30 +1077,21 @@ out_bad: } EXPORT_SYMBOL(__skb_flow_dissect); -static u32 hashrnd __read_mostly; +static siphash_key_t hashrnd __read_mostly; static __always_inline void __flow_hash_secret_init(void) { net_get_random_once(&hashrnd, sizeof(hashrnd)); } -static __always_inline u32 __flow_hash_words(const u32 *words, u32 length, - u32 keyval) +static const void *flow_keys_hash_start(const struct flow_keys *flow) { - return jhash2(words, length, keyval); -} - -static inline const u32 *flow_keys_hash_start(const struct flow_keys *flow) -{ - const void *p = flow; - - BUILD_BUG_ON(FLOW_KEYS_HASH_OFFSET % sizeof(u32)); - return (const u32 *)(p + FLOW_KEYS_HASH_OFFSET); + BUILD_BUG_ON(FLOW_KEYS_HASH_OFFSET % SIPHASH_ALIGNMENT); + return &flow->FLOW_KEYS_HASH_START_FIELD; } static inline size_t flow_keys_hash_length(const struct flow_keys *flow) { size_t diff = FLOW_KEYS_HASH_OFFSET + sizeof(flow->addrs); - BUILD_BUG_ON((sizeof(*flow) - FLOW_KEYS_HASH_OFFSET) % sizeof(u32)); BUILD_BUG_ON(offsetof(typeof(*flow), addrs) != sizeof(*flow) - sizeof(flow->addrs)); @@ -1115,7 +1106,7 @@ static inline size_t flow_keys_hash_leng diff -= sizeof(flow->addrs.tipckey); break; } - return (sizeof(*flow) - diff) / sizeof(u32); + return sizeof(*flow) - diff; } __be32 flow_get_u32_src(const struct flow_keys *flow) @@ -1181,14 +1172,15 @@ static inline void __flow_hash_consisten } } -static inline u32 __flow_hash_from_keys(struct flow_keys *keys, u32 keyval) +static inline u32 __flow_hash_from_keys(struct flow_keys *keys, + const siphash_key_t *keyval) { u32 hash; __flow_hash_consistentify(keys); - hash = __flow_hash_words(flow_keys_hash_start(keys), - flow_keys_hash_length(keys), keyval); + hash = siphash(flow_keys_hash_start(keys), + flow_keys_hash_length(keys), keyval); if (!hash) hash = 1; @@ -1198,12 +1190,13 @@ static inline u32 __flow_hash_from_keys( u32 flow_hash_from_keys(struct flow_keys *keys) { __flow_hash_secret_init(); - return __flow_hash_from_keys(keys, hashrnd); + return __flow_hash_from_keys(keys, &hashrnd); } EXPORT_SYMBOL(flow_hash_from_keys); static inline u32 ___skb_get_hash(const struct sk_buff *skb, - struct flow_keys *keys, u32 keyval) + struct flow_keys *keys, + const siphash_key_t *keyval) { skb_flow_dissect_flow_keys(skb, keys, FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); @@ -1251,7 +1244,7 @@ u32 __skb_get_hash_symmetric(const struc NULL, 0, 0, 0, FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL); - return __flow_hash_from_keys(&keys, hashrnd); + return __flow_hash_from_keys(&keys, &hashrnd); } EXPORT_SYMBOL_GPL(__skb_get_hash_symmetric); @@ -1271,13 +1264,14 @@ void __skb_get_hash(struct sk_buff *skb) __flow_hash_secret_init(); - hash = ___skb_get_hash(skb, &keys, hashrnd); + hash = ___skb_get_hash(skb, &keys, &hashrnd); __skb_set_sw_hash(skb, hash, flow_keys_have_l4(&keys)); } EXPORT_SYMBOL(__skb_get_hash); -__u32 skb_get_hash_perturb(const struct sk_buff *skb, u32 perturb) +__u32 skb_get_hash_perturb(const struct sk_buff *skb, + const siphash_key_t *perturb) { struct flow_keys keys; --- a/net/sched/sch_hhf.c +++ b/net/sched/sch_hhf.c @@ -4,11 +4,11 @@ * Copyright (C) 2013 Nandita Dukkipati */ -#include #include #include #include #include +#include #include #include @@ -125,7 +125,7 @@ struct wdrr_bucket { struct hhf_sched_data { struct wdrr_bucket buckets[WDRR_BUCKET_CNT]; - u32 perturbation; /* hash perturbation */ + siphash_key_t perturbation; /* hash perturbation */ u32 quantum; /* psched_mtu(qdisc_dev(sch)); */ u32 drop_overlimit; /* number of times max qdisc packet * limit was hit @@ -263,7 +263,7 @@ static enum wdrr_bucket_idx hhf_classify } /* Get hashed flow-id of the skb. */ - hash = skb_get_hash_perturb(skb, q->perturbation); + hash = skb_get_hash_perturb(skb, &q->perturbation); /* Check if this packet belongs to an already established HH flow. */ flow_pos = hash & HHF_BIT_MASK; @@ -580,7 +580,7 @@ static int hhf_init(struct Qdisc *sch, s sch->limit = 1000; q->quantum = psched_mtu(qdisc_dev(sch)); - q->perturbation = prandom_u32(); + get_random_bytes(&q->perturbation, sizeof(q->perturbation)); INIT_LIST_HEAD(&q->new_buckets); INIT_LIST_HEAD(&q->old_buckets); --- a/net/sched/sch_sfb.c +++ b/net/sched/sch_sfb.c @@ -22,7 +22,7 @@ #include #include #include -#include +#include #include #include #include @@ -49,7 +49,7 @@ struct sfb_bucket { * (Section 4.4 of SFB reference : moving hash functions) */ struct sfb_bins { - u32 perturbation; /* jhash perturbation */ + siphash_key_t perturbation; /* siphash key */ struct sfb_bucket bins[SFB_LEVELS][SFB_NUMBUCKETS]; }; @@ -221,7 +221,8 @@ static u32 sfb_compute_qlen(u32 *prob_r, static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q) { - q->bins[slot].perturbation = prandom_u32(); + get_random_bytes(&q->bins[slot].perturbation, + sizeof(q->bins[slot].perturbation)); } static void sfb_swap_slot(struct sfb_sched_data *q) @@ -318,9 +319,9 @@ static int sfb_enqueue(struct sk_buff *s /* If using external classifiers, get result and record it. */ if (!sfb_classify(skb, fl, &ret, &salt)) goto other_drop; - sfbhash = jhash_1word(salt, q->bins[slot].perturbation); + sfbhash = siphash_1u32(salt, &q->bins[slot].perturbation); } else { - sfbhash = skb_get_hash_perturb(skb, q->bins[slot].perturbation); + sfbhash = skb_get_hash_perturb(skb, &q->bins[slot].perturbation); } @@ -356,7 +357,7 @@ static int sfb_enqueue(struct sk_buff *s /* Inelastic flow */ if (q->double_buffering) { sfbhash = skb_get_hash_perturb(skb, - q->bins[slot].perturbation); + &q->bins[slot].perturbation); if (!sfbhash) sfbhash = 1; sfb_skb_cb(skb)->hashes[slot] = sfbhash; --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -18,7 +18,7 @@ #include #include #include -#include +#include #include #include #include @@ -121,7 +121,7 @@ struct sfq_sched_data { u8 headdrop; u8 maxdepth; /* limit of packets per flow */ - u32 perturbation; + siphash_key_t perturbation; u8 cur_depth; /* depth of longest slot */ u8 flags; unsigned short scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */ @@ -161,7 +161,7 @@ static inline struct sfq_head *sfq_dep_h static unsigned int sfq_hash(const struct sfq_sched_data *q, const struct sk_buff *skb) { - return skb_get_hash_perturb(skb, q->perturbation) & (q->divisor - 1); + return skb_get_hash_perturb(skb, &q->perturbation) & (q->divisor - 1); } static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch, @@ -611,9 +611,11 @@ static void sfq_perturbation(struct time struct sfq_sched_data *q = from_timer(q, t, perturb_timer); struct Qdisc *sch = q->sch; spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); + siphash_key_t nkey; + get_random_bytes(&nkey, sizeof(nkey)); spin_lock(root_lock); - q->perturbation = prandom_u32(); + q->perturbation = nkey; if (!q->filter_list && q->tail) sfq_rehash(sch); spin_unlock(root_lock); @@ -692,7 +694,7 @@ static int sfq_change(struct Qdisc *sch, del_timer(&q->perturb_timer); if (q->perturb_period) { mod_timer(&q->perturb_timer, jiffies + q->perturb_period); - q->perturbation = prandom_u32(); + get_random_bytes(&q->perturbation, sizeof(q->perturbation)); } sch_tree_unlock(sch); kfree(p); @@ -749,7 +751,7 @@ static int sfq_init(struct Qdisc *sch, s q->quantum = psched_mtu(qdisc_dev(sch)); q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); q->perturb_period = 0; - q->perturbation = prandom_u32(); + get_random_bytes(&q->perturbation, sizeof(q->perturbation)); if (opt) { int err = sfq_change(sch, opt);