From patchwork Thu Feb 27 18:49:16 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 11409517 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6D1C692A for ; Thu, 27 Feb 2020 18:50:11 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 9E450246C9 for ; Thu, 27 Feb 2020 18:50:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="OG6B2Rfw" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9E450246C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17980-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 3891 invoked by uid 550); 27 Feb 2020 18:49:43 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 3777 invoked from network); 27 Feb 2020 18:49:41 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=ouVhJC1LzbMtIjBpkBkXzJDLKbzWPj7ADPmF+3aq9S8=; b=OG6B2Rfw8WXvih/kAMqUybWk8GIGuoYhyiiig0hJ/nrhlay/atW71VkkWCmO3elVoF QaLExo/ZTzShrFm5tpX+8MjKZ2mDg0O4jWu4fyTYcKvqYL4g5QcBvbVm0HokSuhJBlvL il7ZxORjHvpWmp8sVdozX+7ilpAJdYmrPdoI4= 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=ouVhJC1LzbMtIjBpkBkXzJDLKbzWPj7ADPmF+3aq9S8=; b=clMx7PQNcptAs44u8s79QkGfS7wsEHcxA8FOKS7idpuhiE4qlJoD4Vexi7mFj/bTcO lAMyHj5mRoeBnUgbPzBKkUzkZaeIJWyFCfCyZFHCk+xgFKRHOIMcfwY24fOhq9WuEXaH sBll5B0Ff2ZzAB8B9JXcsNoTc52ILmoLnV7+VlfKsb9m7ycNe8lSc+3Bv3GxmBFNm1ga wTlGlscWXXywqN+VVpSSiG4LJ4rLvpsQRH6SBgUznJQKmrx5LjChIYPEytfMuZoWUkG1 MX8Y1Pyg7d0mWL2LDWkk9wi3S1T7eNE6xKRxn45F1UNoD5+QZxK0W/DM+fwr0wNNBY2+ Qikw== X-Gm-Message-State: APjAAAWUyitKMuy+qXsaiQP0hkVqtmgf+fBOdspUAcfTExUmiCpn1oxq 4DwyMK/oWuF53aKfVlnKIrJa0g== X-Google-Smtp-Source: APXvYqxoPFpize+vWxACnPinjp3Xb2AGia34FQIMF5BASPpdOh4Xz4Euevk6wQWMUdkrVibU/YAmtQ== X-Received: by 2002:a63:120f:: with SMTP id h15mr716250pgl.235.1582829369446; Thu, 27 Feb 2020 10:49:29 -0800 (PST) From: Kees Cook To: Andrew Morton Cc: Kees Cook , Elena Petrova , Dmitry Vyukov , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Dan Carpenter , "Gustavo A. R. Silva" , Arnd Bergmann , Ard Biesheuvel , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, syzkaller@googlegroups.com Subject: [PATCH v4 1/6] ubsan: Add trap instrumentation option Date: Thu, 27 Feb 2020 10:49:16 -0800 Message-Id: <20200227184921.30215-2-keescook@chromium.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200227184921.30215-1-keescook@chromium.org> References: <20200227184921.30215-1-keescook@chromium.org> MIME-Version: 1.0 The Undefined Behavior Sanitizer can operate in two modes: warning reporting mode via lib/ubsan.c handler calls, or trap mode, which uses __builtin_trap() as the handler. Using lib/ubsan.c means the kernel image is about 5% larger (due to all the debugging text and reporting structures to capture details about the warning conditions). Using the trap mode, the image size changes are much smaller, though at the loss of the "warning only" mode. In order to give greater flexibility to system builders that want minimal changes to image size and are prepared to deal with kernel code being aborted and potentially destabilizing the system, this introduces CONFIG_UBSAN_TRAP. The resulting image sizes comparison: text data bss dec hex filename 19533663 6183037 18554956 44271656 2a38828 vmlinux.stock 19991849 7618513 18874448 46484810 2c54d4a vmlinux.ubsan 19712181 6284181 18366540 44362902 2a4ec96 vmlinux.ubsan-trap CONFIG_UBSAN=y: image +4.8% (text +2.3%, data +18.9%) CONFIG_UBSAN_TRAP=y: image +0.2% (text +0.9%, data +1.6%) Additionally adjusts the CONFIG_UBSAN Kconfig help for clarity and removes the mention of non-existing boot param "ubsan_handle". Suggested-by: Elena Petrova Signed-off-by: Kees Cook Acked-by: Dmitry Vyukov --- lib/Kconfig.ubsan | 22 ++++++++++++++++++---- lib/Makefile | 2 ++ scripts/Makefile.ubsan | 9 +++++++-- 3 files changed, 27 insertions(+), 6 deletions(-) diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan index 0e04fcb3ab3d..9deb655838b0 100644 --- a/lib/Kconfig.ubsan +++ b/lib/Kconfig.ubsan @@ -5,11 +5,25 @@ config ARCH_HAS_UBSAN_SANITIZE_ALL config UBSAN bool "Undefined behaviour sanity checker" help - This option enables undefined behaviour sanity checker + This option enables the Undefined Behaviour sanity checker. Compile-time instrumentation is used to detect various undefined - behaviours in runtime. Various types of checks may be enabled - via boot parameter ubsan_handle - (see: Documentation/dev-tools/ubsan.rst). + behaviours at runtime. For more details, see: + Documentation/dev-tools/ubsan.rst + +config UBSAN_TRAP + bool "On Sanitizer warnings, abort the running kernel code" + depends on UBSAN + depends on $(cc-option, -fsanitize-undefined-trap-on-error) + help + Building kernels with Sanitizer features enabled tends to grow + the kernel size by around 5%, due to adding all the debugging + text on failure paths. To avoid this, Sanitizer instrumentation + can just issue a trap. This reduces the kernel size overhead but + turns all warnings (including potentially harmless conditions) + into full exceptions that abort the running kernel code + (regardless of context, locks held, etc), which may destabilize + the system. For some system builders this is an acceptable + trade-off. config UBSAN_SANITIZE_ALL bool "Enable instrumentation for the entire kernel" diff --git a/lib/Makefile b/lib/Makefile index 611872c06926..55cc8d73cd43 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -279,7 +279,9 @@ quiet_cmd_build_OID_registry = GEN $@ clean-files += oid_registry_data.c obj-$(CONFIG_UCS2_STRING) += ucs2_string.o +ifneq ($(CONFIG_UBSAN_TRAP),y) obj-$(CONFIG_UBSAN) += ubsan.o +endif UBSAN_SANITIZE_ubsan.o := n KASAN_SANITIZE_ubsan.o := n diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan index 019771b845c5..668a91510bfe 100644 --- a/scripts/Makefile.ubsan +++ b/scripts/Makefile.ubsan @@ -1,5 +1,10 @@ # SPDX-License-Identifier: GPL-2.0 ifdef CONFIG_UBSAN + +ifdef CONFIG_UBSAN_ALIGNMENT + CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment) +endif + CFLAGS_UBSAN += $(call cc-option, -fsanitize=shift) CFLAGS_UBSAN += $(call cc-option, -fsanitize=integer-divide-by-zero) CFLAGS_UBSAN += $(call cc-option, -fsanitize=unreachable) @@ -9,8 +14,8 @@ ifdef CONFIG_UBSAN CFLAGS_UBSAN += $(call cc-option, -fsanitize=bool) CFLAGS_UBSAN += $(call cc-option, -fsanitize=enum) -ifdef CONFIG_UBSAN_ALIGNMENT - CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment) +ifdef CONFIG_UBSAN_TRAP + CFLAGS_UBSAN += $(call cc-option, -fsanitize-undefined-trap-on-error) endif # -fsanitize=* options makes GCC less smart than usual and