From nobody Mon Apr 13 13:14:49 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04C8EC4332F for ; Fri, 11 Nov 2022 21:23:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233654AbiKKVXx (ORCPT ); Fri, 11 Nov 2022 16:23:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234364AbiKKVXf (ORCPT ); Fri, 11 Nov 2022 16:23:35 -0500 Received: from mail-wm1-x32d.google.com (mail-wm1-x32d.google.com [IPv6:2a00:1450:4864:20::32d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DB3B4FD00 for ; Fri, 11 Nov 2022 13:23:33 -0800 (PST) Received: by mail-wm1-x32d.google.com with SMTP id a11-20020a05600c2d4b00b003cf6f5fd9f1so3878081wmg.2 for ; Fri, 11 Nov 2022 13:23:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=arista.com; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=y+sOtKCHPX6pUlFz9QYEx87A43EGANm0QsQ80jIMaa8=; b=iWHnO6vA7nQmLhUDbSJOvV9WG3MeqecBMqEjVKWFFzgNlTivR9NI1OwpD8e1XRoTgA yJkjPecBctBCpJBWZ9nEpRngkG18dzfWFjeymGDKtmZ3sJxT5R97fJXjIYAHSjCYMeR7 UNed8MC2iV8h8P9NfspzoxN4tUYsTvJMvnabcO0uwLyk4NnatCLAbx88mfMCGT5cbgnH eJU3bLLO2ffrG6oHUZP4sOXhCc5fvvh4tYrp+n6vPB0dX9XrebsYE+2EPa479MQijGeA brYa8ZbqAIpDjuRB84RQDtQijRu2aWQw4xoeuZlpn8qGxtI1LYJJzy8G9Urc7ULSC7V1 +h0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=y+sOtKCHPX6pUlFz9QYEx87A43EGANm0QsQ80jIMaa8=; b=34HHoeCiEldVvpRUl9mO5ut7bRtsKy8YQkA4//fB7mOiNVjPdKzpG4AXx22fVubY69 /p6COfkVPYppsFFh2ygwyDiPMumnbRTrrjQVbEWlOMbmBf/GZYPaeEQ7dw2B5LP7wTuD 0RjMbqocaLIlvNR6AOZ8inTrrL6TqyUUV/tmoasOMwiJNo/LtwhjhS62O6YZI2MRTHlI 3/5bZoG3lv4+cCXdvWH4n5WclA/TgvfLtW90zJ+8QSVS7xSujYG8qX0S4N749wuLJ8Nh 6ZayrflX47mE8q1HbL98ahjL3nkeYXr5GYpiBTrucPaNowvPGMfX6QkPhW8yidKDV17W 0iPA== X-Gm-Message-State: ANoB5pk3D0zG3T2MujQp6SqSCWhs3ylJeZuKKqSoNSrb1LYxElTcnroq dXIzdpwj5CQ/aJclFPoLCBOoQnm0Aa89ig== X-Google-Smtp-Source: AA0mqf4DQ5od0MGwnrBJetuwTAYWt0X6/MLUxTB9YNAFDpZAxFWKoE2kiNW0ynaUQH4bbP226WxGUg== X-Received: by 2002:a05:600c:2298:b0:3cf:7c1b:3c29 with SMTP id 24-20020a05600c229800b003cf7c1b3c29mr2534091wmf.23.1668201812138; Fri, 11 Nov 2022 13:23:32 -0800 (PST) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id n18-20020a7bcbd2000000b003cf9bf5208esm9423281wmi.19.2022.11.11.13.23.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Nov 2022 13:23:31 -0800 (PST) From: Dmitry Safonov To: linux-kernel@vger.kernel.org, David Ahern , Eric Dumazet Cc: Dmitry Safonov , Bob Gilligan , "David S. Miller" , Dmitry Safonov <0x7f454c46@gmail.com>, Francesco Ruggeri , Hideaki YOSHIFUJI , Jakub Kicinski , Paolo Abeni , Salam Noureddine , netdev@vger.kernel.org Subject: [PATCH v3 3/3] net/tcp: Disable TCP-MD5 static key on tcp_md5sig_info destruction Date: Fri, 11 Nov 2022 21:23:20 +0000 Message-Id: <20221111212320.1386566-4-dima@arista.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221111212320.1386566-1-dima@arista.com> References: <20221111212320.1386566-1-dima@arista.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" To do that, separate two scenarios: - where it's the first MD5 key on the system, which means that enabling of the static key may need to sleep; - copying of an existing key from a listening socket to the request socket upon receiving a signed TCP segment, where static key was already enabled (when the key was added to the listening socket). Now the life-time of the static branch for TCP-MD5 is until: - last tcp_md5sig_info is destroyed - last socket in time-wait state with MD5 key is closed. Which means that after all sockets with TCP-MD5 keys are gone, the system gets back the performance of disabled md5-key static branch. Signed-off-by: Dmitry Safonov --- include/net/tcp.h | 10 ++++-- net/ipv4/tcp.c | 5 +-- net/ipv4/tcp_ipv4.c | 68 ++++++++++++++++++++++++++++++++-------- net/ipv4/tcp_minisocks.c | 12 +++++-- net/ipv4/tcp_output.c | 4 +-- net/ipv6/tcp_ipv6.c | 10 +++--- 6 files changed, 78 insertions(+), 31 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 14d45661a84d..a0cdf013782a 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -1675,7 +1675,11 @@ int tcp_v4_md5_hash_skb(char *md5_hash, const struct= tcp_md5sig_key *key, const struct sock *sk, const struct sk_buff *skb); int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, int family, u8 prefixlen, int l3index, u8 flags, - const u8 *newkey, u8 newkeylen, gfp_t gfp); + const u8 *newkey, u8 newkeylen); +int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr, + int family, u8 prefixlen, int l3index, + struct tcp_md5sig_key *key); + int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int family, u8 prefixlen, int l3index, u8 flags); struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, @@ -1683,7 +1687,7 @@ struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct= sock *sk, =20 #ifdef CONFIG_TCP_MD5SIG #include -extern struct static_key_false tcp_md5_needed; +extern struct static_key_false_deferred tcp_md5_needed; struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3in= dex, const union tcp_md5_addr *addr, int family); @@ -1691,7 +1695,7 @@ static inline struct tcp_md5sig_key * tcp_md5_do_lookup(const struct sock *sk, int l3index, const union tcp_md5_addr *addr, int family) { - if (!static_branch_unlikely(&tcp_md5_needed)) + if (!static_branch_unlikely(&tcp_md5_needed.key)) return NULL; return __tcp_md5_do_lookup(sk, l3index, addr, family); } diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index 54836a6b81d6..07a73c9b49da 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -4460,11 +4460,8 @@ bool tcp_alloc_md5sig_pool(void) if (unlikely(!READ_ONCE(tcp_md5sig_pool_populated))) { mutex_lock(&tcp_md5sig_mutex); =20 - if (!tcp_md5sig_pool_populated) { + if (!tcp_md5sig_pool_populated) __tcp_alloc_md5sig_pool(); - if (tcp_md5sig_pool_populated) - static_branch_inc(&tcp_md5_needed); - } =20 mutex_unlock(&tcp_md5sig_mutex); } diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index fae80b1a1796..7c4cadbfdc1f 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1064,7 +1064,7 @@ static void tcp_v4_reqsk_destructor(struct request_so= ck *req) * We need to maintain these in the sk structure. */ =20 -DEFINE_STATIC_KEY_FALSE(tcp_md5_needed); +DEFINE_STATIC_KEY_DEFERRED_FALSE(tcp_md5_needed, HZ); EXPORT_SYMBOL(tcp_md5_needed); =20 static bool better_md5_match(struct tcp_md5sig_key *old, struct tcp_md5sig= _key *new) @@ -1177,9 +1177,6 @@ static int tcp_md5sig_info_add(struct sock *sk, gfp_t= gfp) struct tcp_sock *tp =3D tcp_sk(sk); struct tcp_md5sig_info *md5sig; =20 - if (rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))) - return 0; - md5sig =3D kmalloc(sizeof(*md5sig), gfp); if (!md5sig) return -ENOMEM; @@ -1191,9 +1188,9 @@ static int tcp_md5sig_info_add(struct sock *sk, gfp_t= gfp) } =20 /* This can be called on a newly created socket, from other files */ -int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, - int family, u8 prefixlen, int l3index, u8 flags, - const u8 *newkey, u8 newkeylen, gfp_t gfp) +static int __tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *add= r, + int family, u8 prefixlen, int l3index, u8 flags, + const u8 *newkey, u8 newkeylen, gfp_t gfp) { /* Add Key to the list */ struct tcp_md5sig_key *key; @@ -1220,9 +1217,6 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_m= d5_addr *addr, return 0; } =20 - if (tcp_md5sig_info_add(sk, gfp)) - return -ENOMEM; - md5sig =3D rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk)); =20 @@ -1246,8 +1240,56 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_= md5_addr *addr, hlist_add_head_rcu(&key->node, &md5sig->head); return 0; } + +int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, + int family, u8 prefixlen, int l3index, u8 flags, + const u8 *newkey, u8 newkeylen) +{ + struct tcp_sock *tp =3D tcp_sk(sk); + + if (!rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))= ) { + if (tcp_md5sig_info_add(sk, GFP_KERNEL)) + return -ENOMEM; + + if (!static_branch_inc(&tcp_md5_needed.key)) { + struct tcp_md5sig_info *md5sig =3D tp->md5sig_info; + + rcu_assign_pointer(tp->md5sig_info, NULL); + kfree_rcu(md5sig); + return -EUSERS; + } + } + + return __tcp_md5_do_add(sk, addr, family, prefixlen, l3index, flags, + newkey, newkeylen, GFP_KERNEL); +} EXPORT_SYMBOL(tcp_md5_do_add); =20 +int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr, + int family, u8 prefixlen, int l3index, + struct tcp_md5sig_key *key) +{ + struct tcp_sock *tp =3D tcp_sk(sk); + + if (!rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))= ) { + if (tcp_md5sig_info_add(sk, sk_gfp_mask(sk, GFP_ATOMIC))) + return -ENOMEM; + + if (!static_key_fast_inc(&tcp_md5_needed.key.key)) { + struct tcp_md5sig_info *md5sig =3D tp->md5sig_info; + + rcu_assign_pointer(tp->md5sig_info, NULL); + kfree_rcu(md5sig); + return -EUSERS; + } + } + + return __tcp_md5_do_add(sk, addr, family, prefixlen, l3index, + key->flags, key->key, key->keylen, + sk_gfp_mask(sk, GFP_ATOMIC)); +} +EXPORT_SYMBOL(tcp_md5_key_copy); + int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, int fa= mily, u8 prefixlen, int l3index, u8 flags) { @@ -1334,7 +1376,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int= optname, return -EINVAL; =20 return tcp_md5_do_add(sk, addr, AF_INET, prefixlen, l3index, flags, - cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL); + cmd.tcpm_key, cmd.tcpm_keylen); } =20 static int tcp_v4_md5_hash_headers(struct tcp_md5sig_pool *hp, @@ -1591,8 +1633,7 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *= sk, struct sk_buff *skb, * memory, then we end up not copying the key * across. Shucks. */ - tcp_md5_do_add(newsk, addr, AF_INET, 32, l3index, key->flags, - key->key, key->keylen, GFP_ATOMIC); + tcp_md5_key_copy(newsk, addr, AF_INET, 32, l3index, key); sk_gso_disable(newsk); } #endif @@ -2284,6 +2325,7 @@ void tcp_v4_destroy_sock(struct sock *sk) tcp_clear_md5_list(sk); kfree_rcu(rcu_dereference_protected(tp->md5sig_info, 1), rcu); tp->md5sig_info =3D NULL; + static_branch_slow_dec_deferred(&tcp_md5_needed); } #endif =20 diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index c375f603a16c..118fb2d939bb 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -291,13 +291,17 @@ void tcp_time_wait(struct sock *sk, int state, int ti= meo) */ do { tcptw->tw_md5_key =3D NULL; - if (static_branch_unlikely(&tcp_md5_needed)) { + if (static_branch_unlikely(&tcp_md5_needed.key)) { struct tcp_md5sig_key *key; =20 key =3D tp->af_specific->md5_lookup(sk, sk); if (key) { tcptw->tw_md5_key =3D kmemdup(key, sizeof(*key), GFP_ATOMIC); BUG_ON(tcptw->tw_md5_key && !tcp_alloc_md5sig_pool()); + if (!static_key_fast_inc(&tcp_md5_needed.key.key)) { + kfree(tcptw->tw_md5_key); + tcptw->tw_md5_key =3D NULL; + } } } } while (0); @@ -337,11 +341,13 @@ EXPORT_SYMBOL(tcp_time_wait); void tcp_twsk_destructor(struct sock *sk) { #ifdef CONFIG_TCP_MD5SIG - if (static_branch_unlikely(&tcp_md5_needed)) { + if (static_branch_unlikely(&tcp_md5_needed.key)) { struct tcp_timewait_sock *twsk =3D tcp_twsk(sk); =20 - if (twsk->tw_md5_key) + if (twsk->tw_md5_key) { kfree_rcu(twsk->tw_md5_key, rcu); + static_branch_slow_dec_deferred(&tcp_md5_needed); + } } #endif } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index c69f4d966024..86e71c8c76bc 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -766,7 +766,7 @@ static unsigned int tcp_syn_options(struct sock *sk, st= ruct sk_buff *skb, =20 *md5 =3D NULL; #ifdef CONFIG_TCP_MD5SIG - if (static_branch_unlikely(&tcp_md5_needed) && + if (static_branch_unlikely(&tcp_md5_needed.key) && rcu_access_pointer(tp->md5sig_info)) { *md5 =3D tp->af_specific->md5_lookup(sk, sk); if (*md5) { @@ -922,7 +922,7 @@ static unsigned int tcp_established_options(struct sock= *sk, struct sk_buff *skb =20 *md5 =3D NULL; #ifdef CONFIG_TCP_MD5SIG - if (static_branch_unlikely(&tcp_md5_needed) && + if (static_branch_unlikely(&tcp_md5_needed.key) && rcu_access_pointer(tp->md5sig_info)) { *md5 =3D tp->af_specific->md5_lookup(sk, sk); if (*md5) { diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index 2a3f9296df1e..3e3bdc120fc8 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -677,12 +677,11 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, int= optname, if (ipv6_addr_v4mapped(&sin6->sin6_addr)) return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr= 32[3], AF_INET, prefixlen, l3index, flags, - cmd.tcpm_key, cmd.tcpm_keylen, - GFP_KERNEL); + cmd.tcpm_key, cmd.tcpm_keylen); =20 return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr, AF_INET6, prefixlen, l3index, flags, - cmd.tcpm_key, cmd.tcpm_keylen, GFP_KERNEL); + cmd.tcpm_key, cmd.tcpm_keylen); } =20 static int tcp_v6_md5_hash_headers(struct tcp_md5sig_pool *hp, @@ -1382,9 +1381,8 @@ static struct sock *tcp_v6_syn_recv_sock(const struct= sock *sk, struct sk_buff * * memory, then we end up not copying the key * across. Shucks. */ - tcp_md5_do_add(newsk, (union tcp_md5_addr *)&newsk->sk_v6_daddr, - AF_INET6, 128, l3index, key->flags, key->key, key->keylen, - sk_gfp_mask(sk, GFP_ATOMIC)); + tcp_md5_key_copy(newsk, (union tcp_md5_addr *)&newsk->sk_v6_daddr, + AF_INET6, 128, l3index, key); } #endif =20 --=20 2.38.1