From patchwork Fri Nov 11 21:23:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Safonov X-Patchwork-Id: 13040793 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 CD9A1C4332F for ; Fri, 11 Nov 2022 21:23:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234376AbiKKVXg (ORCPT ); Fri, 11 Nov 2022 16:23:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48888 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234025AbiKKVXc (ORCPT ); Fri, 11 Nov 2022 16:23:32 -0500 Received: from mail-wr1-x42c.google.com (mail-wr1-x42c.google.com [IPv6:2a00:1450:4864:20::42c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8A829FF6 for ; Fri, 11 Nov 2022 13:23:30 -0800 (PST) Received: by mail-wr1-x42c.google.com with SMTP id j15so7980418wrq.3 for ; Fri, 11 Nov 2022 13:23:30 -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=/wqu7ka025DHmiQHo96XTmKANEmftj8UjKkUsPUJ5+A=; b=fxVJwfPadmX2Uf5lD3RgJFfhZGXHqr6rP7D8M4ssAK4uU5IWGA4BJkQKPdVttgZO+v uXmVGi6Qgm563iisXM1+ajmiPXYAsXb99/we41xRtyFyhDvvDRZC8JPD9I/7OpCUqjVj lUTPyvEtnEF6q4PNqyi0LwMAh7Ssg8QqgqdkV9Bx/xXvspGSWleBm83YkbIx7nY3+C+E ffQkoIU0G6sAtFXGMlkKE5hog0L+8Yj5cXwmrwtBijDE4XmlKDip1EhBxi1441SQ6taO 2fN94oJE07p69DqUZPt7ICKiGdM2wTBzV9ok2L80GKrDG8/3wzotNFYnYwAejO3PXXMk 6Lkw== 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=/wqu7ka025DHmiQHo96XTmKANEmftj8UjKkUsPUJ5+A=; b=sLYa1sWPCZipq0d8J3HJBVv2wW7mKcpiF5xTe8ojQYOQjYxXFmk3k5+lCcRq9fsbpk HZ7bDhdSvWkRqqshKbW0UvJEEYoue3wcAdILpalAVAVAK/oXL3wPrlRbREr9HcGkIPdB ONoPmtLMujZ13zZFd7bdin213dz7GwZIw7rA0f43LJXeGXj3HQYiFZeWhJhzk5S+FNLI 3A/GPlLxxjitIUkGgNHj+gn05BM1+WfxDPF7zF3p4FK1izK0l+ZLumNtnIsfbEebPNSO OfMYba++h+0yhv0uGajqkytSKsNe/va+wssX7IkYWVDozsbA/B+m2/4FNELa2tRppvpn r4VQ== X-Gm-Message-State: ANoB5pkt+3ghXlhiTXbfap9/R7a256mWyTneb9Pevzh1WyWNXo2TRkgz h4fL3LHmStK2AGJtTqwhrUKJsQ== X-Google-Smtp-Source: AA0mqf5qyVUOYbiavINF4aCT+lEdbutL4RcNHVO5ns2hb4bESLOXBnavZU1Tx0DyY7qe1LjOnH85mg== X-Received: by 2002:adf:f882:0:b0:236:8dd7:1919 with SMTP id u2-20020adff882000000b002368dd71919mr2114766wrp.242.1668201809379; Fri, 11 Nov 2022 13:23:29 -0800 (PST) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id n18-20020a7bcbd2000000b003cf9bf5208esm9423281wmi.19.2022.11.11.13.23.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Nov 2022 13:23:28 -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, Ard Biesheuvel , Jason Baron , Josh Poimboeuf , Peter Zijlstra , Steven Rostedt Subject: [PATCH v3 1/3] jump_label: Prevent key->enabled int overflow Date: Fri, 11 Nov 2022 21:23:18 +0000 Message-Id: <20221111212320.1386566-2-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 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 1. With CONFIG_JUMP_LABEL=n static_key_slow_inc() doesn't have any protection against key->enabled refcounter overflow. 2. With CONFIG_JUMP_LABEL=y static_key_slow_inc_cpuslocked() still may turn the refcounter negative as (v + 1) may overflow. key->enabled is indeed a ref-counter as it's documented in multiple places: top comment in jump_label.h, Documentation/staging/static-keys.rst, etc. As -1 is reserved for static key that's in process of being enabled, functions would break with negative key->enabled refcount: - for CONFIG_JUMP_LABEL=n negative return of static_key_count() breaks static_key_false(), static_key_true() - the ref counter may become 0 from negative side by too many static_key_slow_inc() calls and lead to use-after-free issues. These flaws result in that some users have to introduce an additional mutex and prevent the reference counter from overflowing themselves, see bpf_enable_runtime_stats() checking the counter against INT_MAX / 2. Prevent the reference counter overflow by checking if (v + 1) > 0. Change functions API to return whether the increment was successful. While at here, provide static_key_fast_inc() helper that does ref counter increment in atomic fashion (without grabbing cpus_read_lock() on CONFIG_JUMP_LABEL=y). This is needed to add a new user for a static_key when the caller controls the lifetime of another user. The exact detail where it will be used: if a listen socket with TCP-MD5 key receives SYN packet that passes the verification and in result creates a request socket - it's all done from RX softirq. At that moment userspace can't lock the listen socket and remove that TCP-MD5 key, so the tcp_md5_needed static branch can't get disabled. But the refcounter of the static key needs to be adjusted to account for a new user (the request socket). Cc: Ard Biesheuvel Cc: Eric Dumazet Cc: Jason Baron Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: Steven Rostedt Signed-off-by: Dmitry Safonov --- include/linux/jump_label.h | 21 ++++++++++++--- kernel/jump_label.c | 54 ++++++++++++++++++++++++++++---------- 2 files changed, 57 insertions(+), 18 deletions(-) diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index 570831ca9951..ced5b49d24b4 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -224,9 +224,10 @@ extern bool arch_jump_label_transform_queue(struct jump_entry *entry, enum jump_label_type type); extern void arch_jump_label_transform_apply(void); extern int jump_label_text_reserved(void *start, void *end); -extern void static_key_slow_inc(struct static_key *key); +extern bool static_key_slow_inc(struct static_key *key); +extern bool static_key_fast_inc(struct static_key *key); extern void static_key_slow_dec(struct static_key *key); -extern void static_key_slow_inc_cpuslocked(struct static_key *key); +extern bool static_key_slow_inc_cpuslocked(struct static_key *key); extern void static_key_slow_dec_cpuslocked(struct static_key *key); extern int static_key_count(struct static_key *key); extern void static_key_enable(struct static_key *key); @@ -278,11 +279,23 @@ static __always_inline bool static_key_true(struct static_key *key) return false; } -static inline void static_key_slow_inc(struct static_key *key) +static inline bool static_key_fast_inc(struct static_key *key) { + int v, v1; + STATIC_KEY_CHECK_USE(key); - atomic_inc(&key->enabled); + /* + * Prevent key->enabled getting negative to follow the same semantics + * as for CONFIG_JUMP_LABEL=y, see kernel/jump_label.c comment. + */ + for (v = atomic_read(&key->enabled); v >= 0 && (v + 1) > 0; v = v1) { + v1 = atomic_cmpxchg(&key->enabled, v, v + 1); + if (likely(v1 == v)) + return true; + } + return false; } +#define static_key_slow_inc(key) static_key_fast_inc(key) static inline void static_key_slow_dec(struct static_key *key) { diff --git a/kernel/jump_label.c b/kernel/jump_label.c index 714ac4c3b556..f2c1aa351d41 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -113,11 +113,38 @@ int static_key_count(struct static_key *key) } EXPORT_SYMBOL_GPL(static_key_count); -void static_key_slow_inc_cpuslocked(struct static_key *key) +/*** + * static_key_fast_inc - adds a user for a static key + * @key: static key that must be already enabled + * + * The caller must make sure that the static key can't get disabled while + * in this function. It doesn't patch jump labels, only adds a user to + * an already enabled static key. + * + * Returns true if the increment was done. + */ +bool static_key_fast_inc(struct static_key *key) { int v, v1; STATIC_KEY_CHECK_USE(key); + /* + * Negative key->enabled has a special meaning: it sends + * static_key_slow_inc() down the slow path, and it is non-zero + * so it counts as "enabled" in jump_label_update(). Note that + * atomic_inc_unless_negative() checks >= 0, so roll our own. + */ + for (v = atomic_read(&key->enabled); v > 0 && (v + 1) > 0; v = v1) { + v1 = atomic_cmpxchg(&key->enabled, v, v + 1); + if (likely(v1 == v)) + return true; + } + return false; +} +EXPORT_SYMBOL_GPL(static_key_fast_inc); + +bool static_key_slow_inc_cpuslocked(struct static_key *key) +{ lockdep_assert_cpus_held(); /* @@ -126,17 +153,9 @@ void static_key_slow_inc_cpuslocked(struct static_key *key) * jump_label_update() process. At the same time, however, * the jump_label_update() call below wants to see * static_key_enabled(&key) for jumps to be updated properly. - * - * So give a special meaning to negative key->enabled: it sends - * static_key_slow_inc() down the slow path, and it is non-zero - * so it counts as "enabled" in jump_label_update(). Note that - * atomic_inc_unless_negative() checks >= 0, so roll our own. */ - for (v = atomic_read(&key->enabled); v > 0; v = v1) { - v1 = atomic_cmpxchg(&key->enabled, v, v + 1); - if (likely(v1 == v)) - return; - } + if (static_key_fast_inc(key)) + return true; jump_label_lock(); if (atomic_read(&key->enabled) == 0) { @@ -148,16 +167,23 @@ void static_key_slow_inc_cpuslocked(struct static_key *key) */ atomic_set_release(&key->enabled, 1); } else { - atomic_inc(&key->enabled); + if (WARN_ON_ONCE(static_key_fast_inc(key))) { + jump_label_unlock(); + return false; + } } jump_label_unlock(); + return true; } -void static_key_slow_inc(struct static_key *key) +bool static_key_slow_inc(struct static_key *key) { + bool ret; + cpus_read_lock(); - static_key_slow_inc_cpuslocked(key); + ret = static_key_slow_inc_cpuslocked(key); cpus_read_unlock(); + return ret; } EXPORT_SYMBOL_GPL(static_key_slow_inc); From patchwork Fri Nov 11 21:23:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Safonov X-Patchwork-Id: 13040794 X-Patchwork-Delegate: kuba@kernel.org 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 9A720C43217 for ; Fri, 11 Nov 2022 21:23:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234372AbiKKVXi (ORCPT ); Fri, 11 Nov 2022 16:23:38 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234246AbiKKVXd (ORCPT ); Fri, 11 Nov 2022 16:23:33 -0500 Received: from mail-wr1-x436.google.com (mail-wr1-x436.google.com [IPv6:2a00:1450:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E085E0C9 for ; Fri, 11 Nov 2022 13:23:32 -0800 (PST) Received: by mail-wr1-x436.google.com with SMTP id k8so7986552wrh.1 for ; Fri, 11 Nov 2022 13:23:32 -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=CbvR8VuafE8eZOle2gcxzJnLTEWWuPtnJ8HojgPG8FI=; b=f3iG1K2eNxwKyTPazHAOoXdjfhkFgLqsHQrlV3DO0qQzhPY2nNSYzOltjYBsMJqnwf N0PMbUSz284yXm4U3DwFlcT8UmZaYrN9GbKfycF1ANn1MHkigxIQNyvid4+g8yhWsWSw cvYgVzl7Dl23sZ6+RzSwn4vDmKWDOE9tQw0Fjq6YcwX8Tmm8LnMYbKsVC00lIfKUQFJn WM1qs7H8Or0Oiardk5Y6KQeesrnwngCuqE8mv2YOQG5X2Df23Q/OgVGJQqB89GVmx572 zIMGqOr7cI1LbD73t6uC0zLOsoCO4bn2G2BqJXPlhox0WC2ym1Or4BCpc/QuqposuCnm 4vxA== 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=CbvR8VuafE8eZOle2gcxzJnLTEWWuPtnJ8HojgPG8FI=; b=kw5m/EDO7tk6LkltRmBudXC1s0DOSIK08GyaEzvfx8XScaSt7P7nBWNOo5wtUBxh0B meyADtRdfPicvnq6rkExSlsZ8EWhSINA2WisMWnFbCH7ExIZZpFn85OyvkQOapKgmn7L 6anQp247alMm77DCUOsm2+9KInO/aYmJN+oHxzX3WeYZV5u2O80i1/P86UX7cfV3nTST wkIaduN3sKdsjwPnkvu+tm14Vyz8w9ccOp/n3XbWOAUuOC+L+zBtEJrtnSz2ILEvEGxx kO7nAN2pSDoNZgQi0kovsF+0qQai4v9DmL/pku0D4DZjdysG/fE5EI8bW46UJRg1J5+A cqsA== X-Gm-Message-State: ANoB5pm3W/67AtFQ0q8D65b8b3p+PVL3jGnq4aAg2j7dLin93QOILZxH SLfx4RPgiBlBJoX2YSlW/iatQQ== X-Google-Smtp-Source: AA0mqf4Um6FP2tvkVQX8p5z0+5awYzTA+3i5kGqNSR6er7zA7Rj1YrkkvI4pNCIwc7918zmf839yvg== X-Received: by 2002:adf:f4c9:0:b0:236:562b:f67a with SMTP id h9-20020adff4c9000000b00236562bf67amr2216064wrp.562.1668201810780; Fri, 11 Nov 2022 13:23:30 -0800 (PST) Received: from Mindolluin.ire.aristanetworks.com ([217.173.96.166]) by smtp.gmail.com with ESMTPSA id n18-20020a7bcbd2000000b003cf9bf5208esm9423281wmi.19.2022.11.11.13.23.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Nov 2022 13:23:30 -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 2/3] net/tcp: Separate tcp_md5sig_info allocation into tcp_md5sig_info_add() Date: Fri, 11 Nov 2022 21:23:19 +0000 Message-Id: <20221111212320.1386566-3-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 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org Add a helper to allocate tcp_md5sig_info, that will help later to do/allocate things when info allocated, once per socket. Signed-off-by: Dmitry Safonov Reviewed-by: Eric Dumazet --- net/ipv4/tcp_ipv4.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 87d440f47a70..fae80b1a1796 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1172,6 +1172,24 @@ struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, } EXPORT_SYMBOL(tcp_v4_md5_lookup); +static int tcp_md5sig_info_add(struct sock *sk, gfp_t gfp) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_md5sig_info *md5sig; + + if (rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))) + return 0; + + md5sig = kmalloc(sizeof(*md5sig), gfp); + if (!md5sig) + return -ENOMEM; + + sk_gso_disable(sk); + INIT_HLIST_HEAD(&md5sig->head); + rcu_assign_pointer(tp->md5sig_info, md5sig); + return 0; +} + /* 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, @@ -1202,17 +1220,11 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, return 0; } + if (tcp_md5sig_info_add(sk, gfp)) + return -ENOMEM; + md5sig = rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk)); - if (!md5sig) { - md5sig = kmalloc(sizeof(*md5sig), gfp); - if (!md5sig) - return -ENOMEM; - - sk_gso_disable(sk); - INIT_HLIST_HEAD(&md5sig->head); - rcu_assign_pointer(tp->md5sig_info, md5sig); - } key = sock_kmalloc(sk, sizeof(*key), gfp | __GFP_ZERO); if (!key) From patchwork Fri Nov 11 21:23:20 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dmitry Safonov X-Patchwork-Id: 13040795 X-Patchwork-Delegate: kuba@kernel.org 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 7A876C433FE for ; Fri, 11 Nov 2022 21:23:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234438AbiKKVXl (ORCPT ); Fri, 11 Nov 2022 16:23:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48914 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234357AbiKKVXf (ORCPT ); Fri, 11 Nov 2022 16:23:35 -0500 Received: from mail-wm1-x32c.google.com (mail-wm1-x32c.google.com [IPv6:2a00:1450:4864:20::32c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A64A0F590 for ; Fri, 11 Nov 2022 13:23:33 -0800 (PST) Received: by mail-wm1-x32c.google.com with SMTP id c3-20020a1c3503000000b003bd21e3dd7aso6344211wma.1 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=crKqiLqSqafK5iIzIIdbMqqo7J3jmY/wcMLdNWkrPFOXfJNxvBGaKUdOvadY8Of4bK wdP/y3/IU4ucFrbuB7L1mJgG5D039Yxl23ilUPm2nSPJTfyJlSsNm6XPi/pCwHjMFC3r mt8Outg1+O34SpS1NtNZApAlbF8k7Bmv7eqw2Oz7fCxOT0N5wHxsMZ7k/HeU0+uHyrn3 1FYv0YOusiOxe839VNkIi1SNmaJNCedkb12TxiSeZ/Hp9uFyN0/kQHlBpwppgWbC1f8V I/Ew88GbGXYayeHQJJ0dGquXV+KQYefUT5C664M+8VATYKen4AmcfYinGAl3OAjMhbdK qlmA== X-Gm-Message-State: ANoB5pk9ZnBI5lZHrUv+NY6QTVw0XESaACCs1ALbB/0NJl7Dm3wD3V1x lSC+RycfYMyo46Q9BIVf/3+V8x9FnZMWMw== 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 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org 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, #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 l3index, 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); - 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); - } 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_sock *req) * We need to maintain these in the sk structure. */ -DEFINE_STATIC_KEY_FALSE(tcp_md5_needed); +DEFINE_STATIC_KEY_DEFERRED_FALSE(tcp_md5_needed, HZ); EXPORT_SYMBOL(tcp_md5_needed); 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 = tcp_sk(sk); struct tcp_md5sig_info *md5sig; - if (rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk))) - return 0; - md5sig = kmalloc(sizeof(*md5sig), gfp); if (!md5sig) return -ENOMEM; @@ -1191,9 +1188,9 @@ static int tcp_md5sig_info_add(struct sock *sk, gfp_t gfp) } /* 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 *addr, + 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_md5_addr *addr, return 0; } - if (tcp_md5sig_info_add(sk, gfp)) - return -ENOMEM; - md5sig = rcu_dereference_protected(tp->md5sig_info, lockdep_sock_is_held(sk)); @@ -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 = 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 = 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); +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 = 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 = 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 family, u8 prefixlen, int l3index, u8 flags) { @@ -1334,7 +1376,7 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, int optname, return -EINVAL; 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); } 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 = NULL; + static_branch_slow_dec_deferred(&tcp_md5_needed); } #endif 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 timeo) */ do { tcptw->tw_md5_key = NULL; - if (static_branch_unlikely(&tcp_md5_needed)) { + if (static_branch_unlikely(&tcp_md5_needed.key)) { struct tcp_md5sig_key *key; key = tp->af_specific->md5_lookup(sk, sk); if (key) { tcptw->tw_md5_key = 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 = 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 = tcp_twsk(sk); - 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, struct sk_buff *skb, *md5 = 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 = 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 *md5 = 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 = 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_addr32[3], AF_INET, prefixlen, l3index, flags, - cmd.tcpm_key, cmd.tcpm_keylen, - GFP_KERNEL); + cmd.tcpm_key, cmd.tcpm_keylen); 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); } 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