From patchwork Mon Oct 4 20:22:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vincenzo Frascino X-Patchwork-Id: 12534773 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D9B4C433EF for ; Mon, 4 Oct 2021 20:27:32 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E0767611F0 for ; Mon, 4 Oct 2021 20:27:31 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E0767611F0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=5IQPNKXxGCDdAMQ8FUnhD7NaXwJIMyMLmwm3Zj0rdOk=; b=mdMV4juI1JHCza ASYUO5ITpkYjOC96UtbsKvsclmoDcgglqQ2fENIhv05qV8V34qIo94Y7V6eTtmt9wKJj8XCj1LALd YGcw3g13BrXkLVivbXOjJEQL7CYUsKPXX25rZ/dKIdcqVTo5qbU05U3nTkERPwRJ318G3YQTsXxty ZBhJVKkPq92zFxY0ixwVTTFDLQjAC4g2E+qB3OXYD2a6cwFIDjjkGMsYzbghEU1fo2bBZqLBXkO4C VsnKBRGK5kiuZOAt4gP5uU7a2KLn71kOpg7cB9UGhedQ8go5LblmrdL6suSzytL4D85JKfsCHVgLI y11YoQ6AOAGgEgeOLa8A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mXUWO-007zF5-10; Mon, 04 Oct 2021 20:25:12 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mXUUb-007y2a-T8 for linux-arm-kernel@lists.infradead.org; Mon, 04 Oct 2021 20:23:23 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 82065113E; Mon, 4 Oct 2021 13:23:20 -0700 (PDT) Received: from e119884-lin.cambridge.arm.com (e119884-lin.cambridge.arm.com [10.1.196.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7F6253F70D; Mon, 4 Oct 2021 13:23:18 -0700 (PDT) From: Vincenzo Frascino To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Cc: vincenzo.frascino@arm.com, Andrew Morton , Catalin Marinas , Will Deacon , Dmitry Vyukov , Andrey Ryabinin , Alexander Potapenko , Marco Elver , Evgenii Stepanov , Branislav Rankov , Andrey Konovalov , Lorenzo Pieralisi Subject: [PATCH v2 5/5] kasan: Extend KASAN mode kernel parameter Date: Mon, 4 Oct 2021 21:22:53 +0100 Message-Id: <20211004202253.27857-6-vincenzo.frascino@arm.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20211004202253.27857-1-vincenzo.frascino@arm.com> References: <20211004202253.27857-1-vincenzo.frascino@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211004_132322_095282_B20AFF98 X-CRM114-Status: GOOD ( 20.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Architectures supported by KASAN_HW_TAGS can provide an asymmetric mode of execution. On an MTE enabled arm64 hw for example this can be identified with the asymmetric tagging mode of execution. In particular, when such a mode is present, the CPU triggers a fault on a tag mismatch during a load operation and asynchronously updates a register when a tag mismatch is detected during a store operation. Extend the KASAN HW execution mode kernel command line parameter to support asymmetric mode. Cc: Dmitry Vyukov Cc: Andrey Ryabinin Cc: Alexander Potapenko Cc: Andrey Konovalov Signed-off-by: Vincenzo Frascino Reviewed-by: Catalin Marinas --- Documentation/dev-tools/kasan.rst | 7 +++++-- lib/test_kasan.c | 2 +- mm/kasan/hw_tags.c | 27 ++++++++++++++++++++++----- mm/kasan/kasan.h | 22 +++++++++++++++++++--- mm/kasan/report.c | 2 +- 5 files changed, 48 insertions(+), 12 deletions(-) diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst index 21dc03bc10a4..8089c559d339 100644 --- a/Documentation/dev-tools/kasan.rst +++ b/Documentation/dev-tools/kasan.rst @@ -194,14 +194,17 @@ additional boot parameters that allow disabling KASAN or controlling features: - ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``). -- ``kasan.mode=sync`` or ``=async`` controls whether KASAN is configured in - synchronous or asynchronous mode of execution (default: ``sync``). +- ``kasan.mode=sync``, ``=async`` or ``=asymm`` controls whether KASAN + is configured in synchronous, asynchronous or asymmetric mode of + execution (default: ``sync``). Synchronous mode: a bad access is detected immediately when a tag check fault occurs. Asynchronous mode: a bad access detection is delayed. When a tag check fault occurs, the information is stored in hardware (in the TFSR_EL1 register for arm64). The kernel periodically checks the hardware and only reports tag faults during these checks. + Asymmetric mode: a bad access is detected synchronously on reads and + asynchronously on writes. - ``kasan.stacktrace=off`` or ``=on`` disables or enables alloc and free stack traces collection (default: ``on``). diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 8835e0784578..ebed755ebf34 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -88,7 +88,7 @@ static void kasan_test_exit(struct kunit *test) */ #define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ if (IS_ENABLED(CONFIG_KASAN_HW_TAGS) && \ - !kasan_async_mode_enabled()) \ + kasan_sync_fault_possible()) \ migrate_disable(); \ KUNIT_EXPECT_FALSE(test, READ_ONCE(fail_data.report_found)); \ barrier(); \ diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index 05d1e9460e2e..87eb7aa13918 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -29,6 +29,7 @@ enum kasan_arg_mode { KASAN_ARG_MODE_DEFAULT, KASAN_ARG_MODE_SYNC, KASAN_ARG_MODE_ASYNC, + KASAN_ARG_MODE_ASYMM, }; enum kasan_arg_stacktrace { @@ -49,6 +50,10 @@ EXPORT_SYMBOL(kasan_flag_enabled); bool kasan_flag_async __ro_after_init; EXPORT_SYMBOL_GPL(kasan_flag_async); +/* Whether the asymmetric mode is enabled. */ +bool kasan_flag_asymm __ro_after_init; +EXPORT_SYMBOL_GPL(kasan_flag_asymm); + /* Whether to collect alloc/free stack traces. */ DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace); @@ -69,7 +74,7 @@ static int __init early_kasan_flag(char *arg) } early_param("kasan", early_kasan_flag); -/* kasan.mode=sync/async */ +/* kasan.mode=sync/async/asymm */ static int __init early_kasan_mode(char *arg) { if (!arg) @@ -79,6 +84,8 @@ static int __init early_kasan_mode(char *arg) kasan_arg_mode = KASAN_ARG_MODE_SYNC; else if (!strcmp(arg, "async")) kasan_arg_mode = KASAN_ARG_MODE_ASYNC; + else if (!strcmp(arg, "asymm")) + kasan_arg_mode = KASAN_ARG_MODE_ASYMM; else return -EINVAL; @@ -116,11 +123,13 @@ void kasan_init_hw_tags_cpu(void) return; /* - * Enable async mode only when explicitly requested through - * the command line. + * Enable async or asymm modes only when explicitly requested + * through the command line. */ if (kasan_arg_mode == KASAN_ARG_MODE_ASYNC) hw_enable_tagging_async(); + else if (kasan_arg_mode == KASAN_ARG_MODE_ASYMM) + hw_enable_tagging_asymm(); else hw_enable_tagging_sync(); } @@ -143,16 +152,24 @@ void __init kasan_init_hw_tags(void) case KASAN_ARG_MODE_DEFAULT: /* * Default to sync mode. - * Do nothing, kasan_flag_async keeps its default value. + * Do nothing, kasan_flag_async and kasan_flag_asymm keep + * their default values. */ break; case KASAN_ARG_MODE_SYNC: - /* Do nothing, kasan_flag_async keeps its default value. */ + /* + * Do nothing, kasan_flag_async and kasan_flag_asymm keep + * their default values. + */ break; case KASAN_ARG_MODE_ASYNC: /* Async mode enabled. */ kasan_flag_async = true; break; + case KASAN_ARG_MODE_ASYMM: + /* Asymm mode enabled. */ + kasan_flag_asymm = true; + break; } switch (kasan_arg_stacktrace) { diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 3639e7c8bb98..1d331ce67dec 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -14,15 +14,21 @@ DECLARE_STATIC_KEY_FALSE(kasan_flag_stacktrace); extern bool kasan_flag_async __ro_after_init; +extern bool kasan_flag_asymm __ro_after_init; static inline bool kasan_stack_collection_enabled(void) { return static_branch_unlikely(&kasan_flag_stacktrace); } -static inline bool kasan_async_mode_enabled(void) +static inline bool kasan_async_fault_possible(void) { - return kasan_flag_async; + return kasan_flag_async | kasan_flag_asymm; +} + +static inline bool kasan_sync_fault_possible(void) +{ + return !kasan_flag_async | kasan_flag_asymm; } #else @@ -31,11 +37,16 @@ static inline bool kasan_stack_collection_enabled(void) return true; } -static inline bool kasan_async_mode_enabled(void) +static inline bool kasan_async_fault_possible(void) { return false; } +static inline bool kasan_sync_fault_possible(void) +{ + return true; +} + #endif #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS) @@ -287,6 +298,9 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) #ifndef arch_enable_tagging_async #define arch_enable_tagging_async() #endif +#ifndef arch_enable_tagging_asymm +#define arch_enable_tagging_asymm() +#endif #ifndef arch_force_async_tag_fault #define arch_force_async_tag_fault() #endif @@ -302,6 +316,7 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) #define hw_enable_tagging_sync() arch_enable_tagging_sync() #define hw_enable_tagging_async() arch_enable_tagging_async() +#define hw_enable_tagging_asymm() arch_enable_tagging_asymm() #define hw_force_async_tag_fault() arch_force_async_tag_fault() #define hw_get_random_tag() arch_get_random_tag() #define hw_get_mem_tag(addr) arch_get_mem_tag(addr) @@ -312,6 +327,7 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) #define hw_enable_tagging_sync() #define hw_enable_tagging_async() +#define hw_enable_tagging_asymm() #endif /* CONFIG_KASAN_HW_TAGS */ diff --git a/mm/kasan/report.c b/mm/kasan/report.c index 884a950c7026..9da071ad930c 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -112,7 +112,7 @@ static void start_report(unsigned long *flags) static void end_report(unsigned long *flags, unsigned long addr) { - if (!kasan_async_mode_enabled()) + if (!kasan_async_fault_possible()) trace_error_report_end(ERROR_DETECTOR_KASAN, addr); pr_err("==================================================================\n"); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);