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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 50986C63798 for ; Mon, 23 Nov 2020 20:15:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F2C720731 for ; Mon, 23 Nov 2020 20:15:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="GvA/EBeX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733270AbgKWUPZ (ORCPT ); Mon, 23 Nov 2020 15:15:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43420 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732960AbgKWUPU (ORCPT ); Mon, 23 Nov 2020 15:15:20 -0500 Received: from mail-wr1-x44a.google.com (mail-wr1-x44a.google.com [IPv6:2a00:1450:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADFAAC0613CF for ; Mon, 23 Nov 2020 12:15:20 -0800 (PST) Received: by mail-wr1-x44a.google.com with SMTP id q11so1499584wrw.14 for ; Mon, 23 Nov 2020 12:15:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=jfEhV0tAQhE/zbKKPTCT6UIAQVQtbAcePK8Pzf7KaDc=; b=GvA/EBeXpISUQQVhjYHlsUjv/JDak79nQfzfvbc+M5c9T/dsf4680a8APmqsMLGafj p7nuxeZ28QFdTpZGfLpAOsVoCubT1PFYsepbLUwR6LXDW235BzSeXNYsNl2OfNgyBt08 lev0wm/2pftJkxcYrcsXjAz156X/g3OSLHNeXmOzcMUZrrQXUcQYzcmbtVmiqILtIu0N agbb+oKPO4oTBDSw3ahq8+CQ0Qega7w8eTLqVD1qjuQisczO27qgAZrvsB1kMY+OF73V gQhWCnU8XiIn2nvEXzeboLJn0ieHqEUgjFyLPRl1Gj8w085sVQdIB4ppdOLxzj0LheP0 FKow== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=jfEhV0tAQhE/zbKKPTCT6UIAQVQtbAcePK8Pzf7KaDc=; b=UG3U/ax1gNnaHNGxYyJ6v+XERyL2FHQmq4wmwGMPx9B4pO9uDx9wuuBVGnPTchSNXk tu7HZsb/RMPNMrwDucTlZFcDL7OZMetPLs0R30hB3s3ByZ/FufXmVMW2qrYSw1VOOdic kvw//UEVeCAEP82uXjOe2CaxY57u75UcAnzst8vVTeswV//4/hBD/jhAvrusX001QDXf 7FjsanpU5bJY0OOUcf2ZEPGlcbuE6cNL5mTl9+UoaRkhS4JNoum9Z8qI43RXI8QHnlqk jPkDvYTWOHklGVMStxf5QE/ZtAzfeazSx8HW4hmIbHW1NaiW3V8u/ASLfcCx0hAZZ7ez 2ICA== X-Gm-Message-State: AOAM530X/E2YkVQZTX66O7wvPmuIS7WG43oQHDmCVJnnL3my2Ani3buJ lIfaFZzThQx7EkFl5gL5ovK/wFxlb9+i5ZN/ X-Google-Smtp-Source: ABdhPJygrgUVSwSuWEunXxfKsfeVNdRKIawcizZLcA4jf0vayzOsf1jr5u1nzP7zQ2/7fPEfLE+olHQfI+mhIamu Sender: "andreyknvl via sendgmr" X-Received: from andreyknvl3.muc.corp.google.com ([2a00:79e0:15:13:7220:84ff:fe09:7e9d]) (user=andreyknvl job=sendgmr) by 2002:a1c:9901:: with SMTP id b1mr648770wme.18.1606162519408; Mon, 23 Nov 2020 12:15:19 -0800 (PST) Date: Mon, 23 Nov 2020 21:14:41 +0100 In-Reply-To: Message-Id: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.29.2.454.gaff20da3a2-goog Subject: [PATCH mm v4 11/19] kasan: add and integrate kasan boot parameters From: Andrey Konovalov To: Andrew Morton Cc: Catalin Marinas , Will Deacon , Vincenzo Frascino , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Kevin Brodsky , kasan-dev@googlegroups.com, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrey Konovalov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hardware tag-based KASAN mode is intended to eventually be used in production as a security mitigation. Therefore there's a need for finer control over KASAN features and for an existence of a kill switch. This change adds a few boot parameters for hardware tag-based KASAN that allow to disable or otherwise control particular KASAN features. The features that can be controlled are: 1. Whether KASAN is enabled at all. 2. Whether KASAN collects and saves alloc/free stacks. 3. Whether KASAN panics on a detected bug or not. With this change a new boot parameter kasan.mode allows to choose one of three main modes: - kasan.mode=off - KASAN is disabled, no tag checks are performed - kasan.mode=prod - only essential production features are enabled - kasan.mode=full - all KASAN features are enabled The chosen mode provides default control values for the features mentioned above. However it's also possible to override the default values by providing: - kasan.stacktrace=off/on - enable alloc/free stack collection (default: on for mode=full, otherwise off) - kasan.fault=report/panic - only report tag fault or also panic (default: report) If kasan.mode parameter is not provided, it defaults to full when CONFIG_DEBUG_KERNEL is enabled, and to prod otherwise. It is essential that switching between these modes doesn't require rebuilding the kernel with different configs, as this is required by the Android GKI (Generic Kernel Image) initiative [1]. [1] https://source.android.com/devices/architecture/kernel/generic-kernel-image Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Dmitry Vyukov Link: https://linux-review.googlesource.com/id/If7d37003875b2ed3e0935702c8015c223d6416a4 --- mm/kasan/common.c | 22 +++++-- mm/kasan/hw_tags.c | 151 +++++++++++++++++++++++++++++++++++++++++++++ mm/kasan/kasan.h | 16 +++++ mm/kasan/report.c | 14 ++++- 4 files changed, 196 insertions(+), 7 deletions(-) diff --git a/mm/kasan/common.c b/mm/kasan/common.c index 1ac4f435c679..a11e3e75eb08 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -135,6 +135,11 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, unsigned int redzone_size; int redzone_adjust; + if (!kasan_stack_collection_enabled()) { + *flags |= SLAB_KASAN; + return; + } + /* Add alloc meta. */ cache->kasan_info.alloc_meta_offset = *size; *size += sizeof(struct kasan_alloc_meta); @@ -171,6 +176,8 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size, size_t kasan_metadata_size(struct kmem_cache *cache) { + if (!kasan_stack_collection_enabled()) + return 0; return (cache->kasan_info.alloc_meta_offset ? sizeof(struct kasan_alloc_meta) : 0) + (cache->kasan_info.free_meta_offset ? @@ -263,11 +270,13 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache, { struct kasan_alloc_meta *alloc_meta; - if (!(cache->flags & SLAB_KASAN)) - return (void *)object; + if (kasan_stack_collection_enabled()) { + if (!(cache->flags & SLAB_KASAN)) + return (void *)object; - alloc_meta = kasan_get_alloc_meta(cache, object); - __memset(alloc_meta, 0, sizeof(*alloc_meta)); + alloc_meta = kasan_get_alloc_meta(cache, object); + __memset(alloc_meta, 0, sizeof(*alloc_meta)); + } if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS)) object = set_tag(object, assign_tag(cache, object, true, false)); @@ -307,6 +316,9 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object, rounded_up_size = round_up(cache->object_size, KASAN_GRANULE_SIZE); poison_range(object, rounded_up_size, KASAN_KMALLOC_FREE); + if (!kasan_stack_collection_enabled()) + return false; + if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) || unlikely(!(cache->flags & SLAB_KASAN))) return false; @@ -357,7 +369,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, poison_range((void *)redzone_start, redzone_end - redzone_start, KASAN_KMALLOC_REDZONE); - if (cache->flags & SLAB_KASAN) + if (kasan_stack_collection_enabled() && (cache->flags & SLAB_KASAN)) set_alloc_info(cache, (void *)object, flags); return set_tag(object, tag); diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 863fed4edd3f..30ce88935e9d 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -8,18 +8,115 @@ #define pr_fmt(fmt) "kasan: " fmt +#include #include #include #include #include +#include #include #include #include "kasan.h" +enum kasan_arg_mode { + KASAN_ARG_MODE_DEFAULT, + KASAN_ARG_MODE_OFF, + KASAN_ARG_MODE_PROD, + KASAN_ARG_MODE_FULL, +}; + +enum kasan_arg_stacktrace { + KASAN_ARG_STACKTRACE_DEFAULT, + KASAN_ARG_STACKTRACE_OFF, + KASAN_ARG_STACKTRACE_ON, +}; + +enum kasan_arg_fault { + KASAN_ARG_FAULT_DEFAULT, + KASAN_ARG_FAULT_REPORT, + KASAN_ARG_FAULT_PANIC, +}; + +static enum kasan_arg_mode kasan_arg_mode __ro_after_init; +static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init; +static enum kasan_arg_fault kasan_arg_fault __ro_after_init; + +/* Whether KASAN is enabled at all. */ +DEFINE_STATIC_KEY_FALSE_RO(kasan_flag_enabled); +EXPORT_SYMBOL(kasan_flag_enabled); + +/* Whether to collect alloc/free stack traces. */ +DEFINE_STATIC_KEY_FALSE_RO(kasan_flag_stacktrace); + +/* Whether panic or disable tag checking on fault. */ +bool kasan_flag_panic __ro_after_init; + +/* kasan.mode=off/prod/full */ +static int __init early_kasan_mode(char *arg) +{ + if (!arg) + return -EINVAL; + + if (!strcmp(arg, "off")) + kasan_arg_mode = KASAN_ARG_MODE_OFF; + else if (!strcmp(arg, "prod")) + kasan_arg_mode = KASAN_ARG_MODE_PROD; + else if (!strcmp(arg, "full")) + kasan_arg_mode = KASAN_ARG_MODE_FULL; + else + return -EINVAL; + + return 0; +} +early_param("kasan.mode", early_kasan_mode); + +/* kasan.stack=off/on */ +static int __init early_kasan_flag_stacktrace(char *arg) +{ + if (!arg) + return -EINVAL; + + if (!strcmp(arg, "off")) + kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_OFF; + else if (!strcmp(arg, "on")) + kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_ON; + else + return -EINVAL; + + return 0; +} +early_param("kasan.stacktrace", early_kasan_flag_stacktrace); + +/* kasan.fault=report/panic */ +static int __init early_kasan_fault(char *arg) +{ + if (!arg) + return -EINVAL; + + if (!strcmp(arg, "report")) + kasan_arg_fault = KASAN_ARG_FAULT_REPORT; + else if (!strcmp(arg, "panic")) + kasan_arg_fault = KASAN_ARG_FAULT_PANIC; + else + return -EINVAL; + + return 0; +} +early_param("kasan.fault", early_kasan_fault); + /* kasan_init_hw_tags_cpu() is called for each CPU. */ void kasan_init_hw_tags_cpu(void) { + /* + * There's no need to check that the hardware is MTE-capable here, + * as this function is only called for MTE-capable hardware. + */ + + /* If KASAN is disabled, do nothing. */ + if (kasan_arg_mode == KASAN_ARG_MODE_OFF) + return; + hw_init_tags(KASAN_TAG_MAX); hw_enable_tagging(); } @@ -27,6 +124,60 @@ void kasan_init_hw_tags_cpu(void) /* kasan_init_hw_tags() is called once on boot CPU. */ void __init kasan_init_hw_tags(void) { + /* If hardware doesn't support MTE, do nothing. */ + if (!system_supports_mte()) + return; + + /* Choose KASAN mode if kasan boot parameter is not provided. */ + if (kasan_arg_mode == KASAN_ARG_MODE_DEFAULT) { + if (IS_ENABLED(CONFIG_DEBUG_KERNEL)) + kasan_arg_mode = KASAN_ARG_MODE_FULL; + else + kasan_arg_mode = KASAN_ARG_MODE_PROD; + } + + /* Preset parameter values based on the mode. */ + switch (kasan_arg_mode) { + case KASAN_ARG_MODE_DEFAULT: + /* Shouldn't happen as per the check above. */ + WARN_ON(1); + return; + case KASAN_ARG_MODE_OFF: + /* If KASAN is disabled, do nothing. */ + return; + case KASAN_ARG_MODE_PROD: + static_branch_enable(&kasan_flag_enabled); + break; + case KASAN_ARG_MODE_FULL: + static_branch_enable(&kasan_flag_enabled); + static_branch_enable(&kasan_flag_stacktrace); + break; + } + + /* Now, optionally override the presets. */ + + switch (kasan_arg_stacktrace) { + case KASAN_ARG_STACKTRACE_DEFAULT: + break; + case KASAN_ARG_STACKTRACE_OFF: + static_branch_disable(&kasan_flag_stacktrace); + break; + case KASAN_ARG_STACKTRACE_ON: + static_branch_enable(&kasan_flag_stacktrace); + break; + } + + switch (kasan_arg_fault) { + case KASAN_ARG_FAULT_DEFAULT: + break; + case KASAN_ARG_FAULT_REPORT: + kasan_flag_panic = false; + break; + case KASAN_ARG_FAULT_PANIC: + kasan_flag_panic = true; + break; + } + pr_info("KernelAddressSanitizer initialized\n"); } diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 8aa83b7ad79e..d01a5ac34f70 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -6,6 +6,22 @@ #include #include +#ifdef CONFIG_KASAN_HW_TAGS +#include +DECLARE_STATIC_KEY_FALSE(kasan_flag_stacktrace); +static inline bool kasan_stack_collection_enabled(void) +{ + return static_branch_unlikely(&kasan_flag_stacktrace); +} +#else +static inline bool kasan_stack_collection_enabled(void) +{ + return true; +} +#endif + +extern bool kasan_flag_panic __ro_after_init; + #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) #define KASAN_GRANULE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT) #else diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 76a0e3ae2049..ffa6076b1710 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -99,6 +99,10 @@ static void end_report(unsigned long *flags) panic_on_warn = 0; panic("panic_on_warn set ...\n"); } +#ifdef CONFIG_KASAN_HW_TAGS + if (kasan_flag_panic) + panic("kasan.fault=panic set ...\n"); +#endif kasan_enable_current(); } @@ -161,8 +165,8 @@ static void describe_object_addr(struct kmem_cache *cache, void *object, (void *)(object_addr + cache->object_size)); } -static void describe_object(struct kmem_cache *cache, void *object, - const void *addr, u8 tag) +static void describe_object_stacks(struct kmem_cache *cache, void *object, + const void *addr, u8 tag) { struct kasan_alloc_meta *alloc_meta = kasan_get_alloc_meta(cache, object); @@ -190,7 +194,13 @@ static void describe_object(struct kmem_cache *cache, void *object, } #endif } +} +static void describe_object(struct kmem_cache *cache, void *object, + const void *addr, u8 tag) +{ + if (kasan_stack_collection_enabled()) + describe_object_stacks(cache, object, addr, tag); describe_object_addr(cache, object, addr); } -- 2.29.2.454.gaff20da3a2-goog