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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 A732AC2B9F4 for ; Thu, 17 Jun 2021 06:40:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8491C613F1 for ; Thu, 17 Jun 2021 06:40:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230280AbhFQGmY (ORCPT ); Thu, 17 Jun 2021 02:42:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43266 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230291AbhFQGmV (ORCPT ); Thu, 17 Jun 2021 02:42:21 -0400 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9E0A7C061760 for ; Wed, 16 Jun 2021 23:40:13 -0700 (PDT) Received: by mail-pg1-x531.google.com with SMTP id q15so4099937pgg.12 for ; Wed, 16 Jun 2021 23:40:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axtens.net; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ly/BuIfXTXWQRb2ER2SUgvo52sNSO+fWpTpraSlxuJA=; b=aX8fvAkw0NnLjptOJGjsWgLjfBnZuxomdyEksoWvEoE2hfLu1Ni1jgdXsXXy0bv8iK BmedfPkZ6W8YTgn8JBNTY9jU/jGtvx5bl8BdVJTSNYGbgU6zPe0e8GgguPAdHmMb5kXX smhvtwv/OHiSSjfVGI3g+8gd6NxHg8cKRtoSo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ly/BuIfXTXWQRb2ER2SUgvo52sNSO+fWpTpraSlxuJA=; b=nxJk+wr8CMFlsrhERv0woSxPAhY1OM/zrgPKR/vM91y4oXsbaK7rPM1BRBcAKtGHPD fOUsADQPSx1EEw4CqUSVslTy92KINcJk4MbdXGaKXoTzLFwkXIxuyTLVQvwZd5gzmdqT dWgpk9mP+q5nPGtYUdVlNS4PXRSDuNaVHHFbuKdwoSBGHw6c3wMjJCbPAgLqct8aC5ds 0TXCqy/j/kwZZITWD4jEaz13hS4NM6KcOMBEnqXNN2gOoW1s2fKcpPOHpIACOtbkEAli L7BJkkw43YWZCUhhscixl/U9i1NpevpJxUU+qWjWydAgq0+vX3I6zwOG8tKDJZWgYN5l l1EA== X-Gm-Message-State: AOAM530Q7TZy4yAt6gQgBEid7mKBl/Gr2Zxxb+Dr41XQqNj+TPd2tzuM 9fRLZ4yRK8cnM1CO2hqN6bbmBP5FWRIo3g== X-Google-Smtp-Source: ABdhPJziIh9pak7ePgn640GXrKi8OmoFxF9HwxgtphDZ7oQ/aKdnyEK0aHD02f8BwURqgGolU13O3g== X-Received: by 2002:a65:434c:: with SMTP id k12mr3551339pgq.17.1623912012898; Wed, 16 Jun 2021 23:40:12 -0700 (PDT) Received: from localhost ([203.206.29.204]) by smtp.gmail.com with ESMTPSA id 65sm3950520pfu.159.2021.06.16.23.40.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jun 2021 23:40:12 -0700 (PDT) From: Daniel Axtens To: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, elver@google.com, akpm@linux-foundation.org, andreyknvl@gmail.com Cc: linuxppc-dev@lists.ozlabs.org, christophe.leroy@csgroup.eu, aneesh.kumar@linux.ibm.com, bsingharora@gmail.com, Daniel Axtens , "Aneesh Kumar K . V" Subject: [PATCH v14 2/4] kasan: allow architectures to provide an outline readiness check Date: Thu, 17 Jun 2021 16:39:54 +1000 Message-Id: <20210617063956.94061-3-dja@axtens.net> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210617063956.94061-1-dja@axtens.net> References: <20210617063956.94061-1-dja@axtens.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Allow architectures to define a kasan_arch_is_ready() hook that bails out of any function that's about to touch the shadow unless the arch says that it is ready for the memory to be accessed. This is fairly uninvasive and should have a negligible performance penalty. This will only work in outline mode, so an arch must specify ARCH_DISABLE_KASAN_INLINE if it requires this. Cc: Balbir Singh Cc: Aneesh Kumar K.V Suggested-by: Christophe Leroy Signed-off-by: Daniel Axtens -- Both previous RFCs for ppc64 - by 2 different people - have needed this trick! See: - https://lore.kernel.org/patchwork/patch/592820/ # ppc64 hash series - https://patchwork.ozlabs.org/patch/795211/ # ppc radix series I haven't been able to exercise the arch hook error for !GENERIC as I don't have a particularly modern aarch64 toolchain or a lot of experience cross-compiling with clang. But it does fire for GENERIC + INLINE on x86. --- mm/kasan/common.c | 4 ++++ mm/kasan/generic.c | 3 +++ mm/kasan/kasan.h | 8 ++++++++ mm/kasan/shadow.c | 8 ++++++++ 4 files changed, 23 insertions(+) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 10177cc26d06..0ad615f3801d 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -331,6 +331,10 @@ static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object, u8 tag; void *tagged_object; + /* Bail if the arch isn't ready */ + if (!kasan_arch_is_ready()) + return false; + tag = get_tag(object); tagged_object = object; object = kasan_reset_tag(object); diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index 53cbf28859b5..c3f5ba7a294a 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -163,6 +163,9 @@ static __always_inline bool check_region_inline(unsigned long addr, size_t size, bool write, unsigned long ret_ip) { + if (!kasan_arch_is_ready()) + return true; + if (unlikely(size == 0)) return true; diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 8f450bc28045..b18abaf8c78e 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -449,6 +449,14 @@ static inline void kasan_poison_last_granule(const void *address, size_t size) { #endif /* CONFIG_KASAN_GENERIC */ +#ifndef kasan_arch_is_ready +static inline bool kasan_arch_is_ready(void) { return true; } +#else +#if !defined(CONFIG_KASAN_GENERIC) || !defined(CONFIG_KASAN_OUTLINE) +#error kasan_arch_is_ready only works in KASAN generic outline mode! +#endif +#endif + /* * Exported functions for interfaces called from assembly or from generated * code. Declarations here to avoid warning about missing declarations. diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index 082ee5b6d9a1..3c7f7efe6f68 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -73,6 +73,10 @@ void kasan_poison(const void *addr, size_t size, u8 value, bool init) { void *shadow_start, *shadow_end; + /* Don't touch the shadow memory if arch isn't ready */ + if (!kasan_arch_is_ready()) + return; + /* * Perform shadow offset calculation based on untagged address, as * some of the callers (e.g. kasan_poison_object_data) pass tagged @@ -99,6 +103,10 @@ EXPORT_SYMBOL(kasan_poison); #ifdef CONFIG_KASAN_GENERIC void kasan_poison_last_granule(const void *addr, size_t size) { + /* Don't touch the shadow memory if arch isn't ready */ + if (!kasan_arch_is_ready()) + return; + if (size & KASAN_GRANULE_MASK) { u8 *shadow = (u8 *)kasan_mem_to_shadow(addr + size); *shadow = size & KASAN_GRANULE_MASK; -- 2.30.2