From patchwork Wed Jun 24 12:33:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11623049 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 0205E90 for ; Wed, 24 Jun 2020 12:34:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E8ACF20E65 for ; Wed, 24 Jun 2020 12:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403795AbgFXMeH (ORCPT ); Wed, 24 Jun 2020 08:34:07 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:38534 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388761AbgFXMeF (ORCPT ); Wed, 24 Jun 2020 08:34:05 -0400 Received: by mail-qt1-f196.google.com with SMTP id z2so1484338qts.5; Wed, 24 Jun 2020 05:34:05 -0700 (PDT) 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=r8hAW61/4BUI+NbyFnYc6YqQQjo8d8HK1rSbMU2IkRk=; b=DiHfLU1fxBkDc320X8WPOpj7EmmwPUe3YGc4AtX0OQamNzH0GcM46K/GgOMUDGI40v +n/Bzqnl9GIeLlEL2nRP0FcjBR0Fif0m1FFpNcw2z0D0rFChPGGfGMQ46LYSfneGsRAL janHdWU72hVTr5oVG2FMytgKIIw3/+EiwCBjkRmDzxdfGWMbVXbKqLbTmyEPJL8MQAJn AkoSDxxLaOD1216aiODskcCiqRgy0vDSxSwjO5zJjuFSKOEqD7wuEAjsZeAsCJJzS4XP jeOlxiLdHTg2nabm3DH/PLRDqZqU7p0Jx+bU3okMJT3aTrbaM/fz8x1C4ZLBpnPLaMzz +2Cw== X-Gm-Message-State: AOAM530c9J7LJ1p0706DAI/qzVQb6vsTyUNRSbHt8HRe0JgGqdG9UCJN Eu/36Nk6yzp/hfdHNBjnFbc= X-Google-Smtp-Source: ABdhPJxPh8KCe1nlxIC9hfI7A611S0zDh6pUHr/hn9DXDH26nDPy4DCeItaOwQUW8SJpgZNlzgTiJw== X-Received: by 2002:aed:25a2:: with SMTP id x31mr24822436qtc.96.1593002044717; Wed, 24 Jun 2020 05:34:04 -0700 (PDT) Received: from localhost.localdomain ([185.248.161.177]) by smtp.gmail.com with ESMTPSA id x26sm3354512qtr.4.2020.06.24.05.33.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 05:34:04 -0700 (PDT) From: Alexander Popov To: Kees Cook , Jann Horn , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH v2 1/5] gcc-plugins/stackleak: Don't instrument itself Date: Wed, 24 Jun 2020 15:33:26 +0300 Message-Id: <20200624123330.83226-2-alex.popov@linux.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20200624123330.83226-1-alex.popov@linux.com> References: <20200624123330.83226-1-alex.popov@linux.com> MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org There is no need to try instrumenting functions in kernel/stackleak.c. Otherwise that can cause issues if the cleanup pass of stackleak gcc plugin is disabled. Signed-off-by: Alexander Popov Acked-by: Kees Cook --- kernel/Makefile | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/Makefile b/kernel/Makefile index f3218bc5ec69..155b5380500a 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -125,6 +125,7 @@ obj-$(CONFIG_WATCH_QUEUE) += watch_queue.o obj-$(CONFIG_SYSCTL_KUNIT_TEST) += sysctl-test.o +CFLAGS_stackleak.o += $(DISABLE_STACKLEAK_PLUGIN) obj-$(CONFIG_GCC_PLUGIN_STACKLEAK) += stackleak.o KASAN_SANITIZE_stackleak.o := n KCSAN_SANITIZE_stackleak.o := n From patchwork Wed Jun 24 12:33:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11623055 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 1BECC90 for ; Wed, 24 Jun 2020 12:34:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0E57420EDD for ; Wed, 24 Jun 2020 12:34:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388761AbgFXMeV (ORCPT ); Wed, 24 Jun 2020 08:34:21 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:40131 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388132AbgFXMeR (ORCPT ); Wed, 24 Jun 2020 08:34:17 -0400 Received: by mail-qk1-f194.google.com with SMTP id 80so1582630qko.7; Wed, 24 Jun 2020 05:34:15 -0700 (PDT) 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=NYlBDYPOP+i+Z8CCPoWHLzBw8cVCy1kOHLCJDYgloi0=; b=Um2pPq53cIsmU/SMf9olAn7Fy0Eqf6MlbuYQHWe/zlTbYewfd0U32b9DdyNjbPb5zO DiX+KMpkBcF+g7BT7gQINg8vSjFz/TeXKWu6kAzkAJZECq1/uv7Irp6IZV0/0y83R5wX s5uK54zgb1qckBPQ+9eqyfMW8Jc/CapAd7++LO7IV3AWpoRpxprCtxagLoiig9gqJnBr VSP3MlVMfDCQfJioZahkFHYdLh1LxCzZWNyCmNMS5odYaXwXt2TKwKurErJeguMhpZmH NMVIsuNS3xomQi7ZiOyDbNc98jj8x/P7tKHXRRhScX9wLGDrpiNQ9GSymlNffNd8dHff 8A8g== X-Gm-Message-State: AOAM5329oQz76FQw0bjLfHvJRUvQPnSI/j2RGtW9t5fgwoh6aUX7smIw QfSOsSdYbcV7jbZ61GqtRR8= X-Google-Smtp-Source: ABdhPJxG56K9PcyzErynBCq8WXO4GdEN7iVHSozkebRt9XKZi/zlbyDg2T5l/cdnA0We9Seu6jAYtg== X-Received: by 2002:a37:a785:: with SMTP id q127mr10507259qke.452.1593002055490; Wed, 24 Jun 2020 05:34:15 -0700 (PDT) Received: from localhost.localdomain ([185.248.161.177]) by smtp.gmail.com with ESMTPSA id x26sm3354512qtr.4.2020.06.24.05.34.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 05:34:14 -0700 (PDT) From: Alexander Popov To: Kees Cook , Jann Horn , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH v2 2/5] ARM: vdso: Don't use gcc plugins for building vgettimeofday.c Date: Wed, 24 Jun 2020 15:33:27 +0300 Message-Id: <20200624123330.83226-3-alex.popov@linux.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20200624123330.83226-1-alex.popov@linux.com> References: <20200624123330.83226-1-alex.popov@linux.com> MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Don't use gcc plugins for building arch/arm/vdso/vgettimeofday.c to avoid unneeded instrumentation. Signed-off-by: Alexander Popov --- arch/arm/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/vdso/Makefile b/arch/arm/vdso/Makefile index d3c9f03e7e79..a54f70731d9f 100644 --- a/arch/arm/vdso/Makefile +++ b/arch/arm/vdso/Makefile @@ -29,7 +29,7 @@ CPPFLAGS_vdso.lds += -P -C -U$(ARCH) CFLAGS_REMOVE_vdso.o = -pg # Force -O2 to avoid libgcc dependencies -CFLAGS_REMOVE_vgettimeofday.o = -pg -Os +CFLAGS_REMOVE_vgettimeofday.o = -pg -Os $(GCC_PLUGINS_CFLAGS) ifeq ($(c-gettimeofday-y),) CFLAGS_vgettimeofday.o = -O2 else From patchwork Wed Jun 24 12:33:28 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11623059 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 1CD2392A for ; Wed, 24 Jun 2020 12:34:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FE812100A for ; Wed, 24 Jun 2020 12:34:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390657AbgFXMeb (ORCPT ); Wed, 24 Jun 2020 08:34:31 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:38574 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390646AbgFXMe1 (ORCPT ); Wed, 24 Jun 2020 08:34:27 -0400 Received: by mail-qt1-f196.google.com with SMTP id z2so1485271qts.5; Wed, 24 Jun 2020 05:34:27 -0700 (PDT) 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=dd/x9rNY52s67dtxhdU+GLjXuLmi+ISuyjz/CGrFIjM=; b=NGYb8BWF69d58aMZEBSJDTJ2WfoIzyaBQyGXCLpmS2l1d0l7s6tpwFmJVUSQPwFw4l ffuOCBHy8Tfl5stimfruliPRKtHTEJ8kHF2Xe81rpsnAqTxWoY+Tm/4a8iJ5SHpQNv4W 4OAg+4NOcUxWf8pQaA79GK7lM5JljdiGSY76oYGqHZw2ysOvw15ErQpoUdyb+4pNmLXM Fy2GKbhWH7WwoIuLfT05RCx704qxFPLnvwHCsrpX6mTbl0cVldIQPPKHvcuImCsvcIru Kbdi4Gsjih3cpTJJnvn8WYaoJp+zA6On5fHIM9gRmdjt71LVoQ8NdK8hBRh3H04hekR5 1+Nw== X-Gm-Message-State: AOAM53285VFkuOZyUAz3jNxDeLZ9BGJ5/4XWMxFGyE3yF0rnWTl1YL5J Ecr+8htJVYTRCL0o/TPn3lA= X-Google-Smtp-Source: ABdhPJyKNg/sgqLpXlRp5nWSXUg5BbFE6D7yhTpokmqzn6cNtEQ6n5ShWMctUFdRI9VD2lwP79MMMA== X-Received: by 2002:ac8:5486:: with SMTP id h6mr6019451qtq.255.1593002066620; Wed, 24 Jun 2020 05:34:26 -0700 (PDT) Received: from localhost.localdomain ([185.248.161.177]) by smtp.gmail.com with ESMTPSA id x26sm3354512qtr.4.2020.06.24.05.34.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 05:34:26 -0700 (PDT) From: Alexander Popov To: Kees Cook , Jann Horn , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH v2 3/5] arm64: vdso: Don't use gcc plugins for building vgettimeofday.c Date: Wed, 24 Jun 2020 15:33:28 +0300 Message-Id: <20200624123330.83226-4-alex.popov@linux.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20200624123330.83226-1-alex.popov@linux.com> References: <20200624123330.83226-1-alex.popov@linux.com> MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Don't use gcc plugins for building arch/arm64/kernel/vdso/vgettimeofday.c to avoid unneeded instrumentation. Signed-off-by: Alexander Popov Acked-by: Kees Cook --- arch/arm64/kernel/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index 556d424c6f52..0f1ad63b3326 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile @@ -29,7 +29,7 @@ ldflags-y := -shared -nostdlib -soname=linux-vdso.so.1 --hash-style=sysv \ ccflags-y := -fno-common -fno-builtin -fno-stack-protector -ffixed-x18 ccflags-y += -DDISABLE_BRANCH_PROFILING -CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) $(GCC_PLUGINS_CFLAGS) KBUILD_CFLAGS += $(DISABLE_LTO) KASAN_SANITIZE := n UBSAN_SANITIZE := n From patchwork Wed Jun 24 12:33:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Popov X-Patchwork-Id: 11623069 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 B025990 for ; Wed, 24 Jun 2020 12:35:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96CB020857 for ; Wed, 24 Jun 2020 12:35:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403910AbgFXMeo (ORCPT ); Wed, 24 Jun 2020 08:34:44 -0400 Received: from mail-qt1-f195.google.com ([209.85.160.195]:36131 "EHLO mail-qt1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403891AbgFXMek (ORCPT ); Wed, 24 Jun 2020 08:34:40 -0400 Received: by mail-qt1-f195.google.com with SMTP id x62so1497219qtd.3; Wed, 24 Jun 2020 05:34:38 -0700 (PDT) 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=y4czRrcF8zH3CO6lp92Gxox7EeM3jmLaCFfYGsiywQ8=; b=GBrSQ1s33amMw4QXx6/+mKPViD4qLrACT/Nv5lolYn+J44jcFloF83aIK/qSoWVnEo TjeEhPawhf5gSXm+UE8FOnT2klw2BmE4YbA9UkV5imKM7yOzZ1xi7Mk8bVVmofBkgKEh /TxY9kW/puLVs2n/ZK+QwC1Z3IQ0ML/Tj/jr/YXPWY9MG0QwIRxJTHy1yF8MIsE95LFX 0d5nQg/Oex5veFgkgxRJg10xidocJwYHvMI4uFVZGl62a9gw1GCyhuIPy8H3c5dYs3ep yoezG53Zb0Q6lwKEaZBfhmXwsJj51r2Y8q1on8n1RDlFgl52f/QSeRQV7Cz3JN6IRWGF kOvQ== X-Gm-Message-State: AOAM530ozmNvBwgeUdtq3pBwuQXkZFXoiZsCjjNEHqvoLZ3reX0FMINg Kxw82eeKil9nLNHBk5xRIk8= X-Google-Smtp-Source: ABdhPJwMR5kemIERKfm0W+OpXFOK+gSG7ictSnsXTa1f5CZsDv6zNarK9fLqgQYKuzvvKfSHWnlFDQ== X-Received: by 2002:ac8:263b:: with SMTP id u56mr26577878qtu.388.1593002077584; Wed, 24 Jun 2020 05:34:37 -0700 (PDT) Received: from localhost.localdomain ([185.248.161.177]) by smtp.gmail.com with ESMTPSA id x26sm3354512qtr.4.2020.06.24.05.34.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 05:34:36 -0700 (PDT) From: Alexander Popov To: Kees Cook , Jann Horn , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH v2 4/5] gcc-plugins/stackleak: Use asm instrumentation to avoid useless register saving Date: Wed, 24 Jun 2020 15:33:29 +0300 Message-Id: <20200624123330.83226-5-alex.popov@linux.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20200624123330.83226-1-alex.popov@linux.com> References: <20200624123330.83226-1-alex.popov@linux.com> MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org The kernel code instrumentation in stackleak gcc plugin works in two stages. At first, stack tracking is added to GIMPLE representation of every function (except some special cases). And later, when stack frame size info is available, stack tracking is removed from the RTL representation of the functions with small stack frame. There is an unwanted side-effect for these functions: some of them do useless work with caller-saved registers. As an example of such case, proc_sys_write without() instrumentation: 55 push %rbp 41 b8 01 00 00 00 mov $0x1,%r8d 48 89 e5 mov %rsp,%rbp e8 11 ff ff ff callq ffffffff81284610 5d pop %rbp c3 retq 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) 00 00 00 proc_sys_write() with instrumentation: 55 push %rbp 48 89 e5 mov %rsp,%rbp 41 56 push %r14 41 55 push %r13 41 54 push %r12 53 push %rbx 49 89 f4 mov %rsi,%r12 48 89 fb mov %rdi,%rbx 49 89 d5 mov %rdx,%r13 49 89 ce mov %rcx,%r14 4c 89 f1 mov %r14,%rcx 4c 89 ea mov %r13,%rdx 4c 89 e6 mov %r12,%rsi 48 89 df mov %rbx,%rdi 41 b8 01 00 00 00 mov $0x1,%r8d e8 f2 fe ff ff callq ffffffff81298e80 5b pop %rbx 41 5c pop %r12 41 5d pop %r13 41 5e pop %r14 5d pop %rbp c3 retq 66 0f 1f 84 00 00 00 nopw 0x0(%rax,%rax,1) 00 00 Let's improve the instrumentation to avoid this: 1. Make stackleak_track_stack() save all register that it works with. Use no_caller_saved_registers attribute for that function. This attribute is available for x86_64 and i386 starting from gcc-7. 2. Insert calling stackleak_track_stack() in asm: asm volatile("call stackleak_track_stack" :: "r" (current_stack_pointer)) Here we use ASM_CALL_CONSTRAINT trick from arch/x86/include/asm/asm.h. The input constraint is taken into account during gcc shrink-wrapping optimization. It is needed to be sure that stackleak_track_stack() call is inserted after the prologue of the containing function, when the stack frame is prepared. This work is a deep reengineering of the idea described on grsecurity blog https://grsecurity.net/resolving_an_unfortunate_stackleak_interaction Signed-off-by: Alexander Popov Acked-by: Miguel Ojeda --- include/linux/compiler_attributes.h | 13 ++ kernel/stackleak.c | 16 +- scripts/Makefile.gcc-plugins | 2 + scripts/gcc-plugins/stackleak_plugin.c | 205 +++++++++++++++++++++---- 4 files changed, 196 insertions(+), 40 deletions(-) diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h index cdf016596659..551ea8cb70b1 100644 --- a/include/linux/compiler_attributes.h +++ b/include/linux/compiler_attributes.h @@ -37,6 +37,7 @@ # define __GCC4_has_attribute___copy__ 0 # define __GCC4_has_attribute___designated_init__ 0 # define __GCC4_has_attribute___externally_visible__ 1 +# define __GCC4_has_attribute___no_caller_saved_registers__ 0 # define __GCC4_has_attribute___noclone__ 1 # define __GCC4_has_attribute___nonstring__ 0 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8) @@ -175,6 +176,18 @@ */ #define __mode(x) __attribute__((__mode__(x))) +/* + * Optional: only supported since gcc >= 7 + * + * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 + * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers + */ +#if __has_attribute(__no_caller_saved_registers__) +# define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__)) +#else +# define __no_caller_saved_registers +#endif + /* * Optional: not supported by clang * diff --git a/kernel/stackleak.c b/kernel/stackleak.c index b193a59fc05b..a8fc9ae1d03d 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -104,19 +104,9 @@ asmlinkage void notrace stackleak_erase(void) } NOKPROBE_SYMBOL(stackleak_erase); -void __used notrace stackleak_track_stack(void) +void __used __no_caller_saved_registers notrace stackleak_track_stack(void) { - /* - * N.B. stackleak_erase() fills the kernel stack with the poison value, - * which has the register width. That code assumes that the value - * of 'lowest_stack' is aligned on the register width boundary. - * - * That is true for x86 and x86_64 because of the kernel stack - * alignment on these platforms (for details, see 'cc_stack_align' in - * arch/x86/Makefile). Take care of that when you port STACKLEAK to - * new platforms. - */ - unsigned long sp = (unsigned long)&sp; + unsigned long sp = current_stack_pointer; /* * Having CONFIG_STACKLEAK_TRACK_MIN_SIZE larger than @@ -125,6 +115,8 @@ void __used notrace stackleak_track_stack(void) */ BUILD_BUG_ON(CONFIG_STACKLEAK_TRACK_MIN_SIZE > STACKLEAK_SEARCH_DEPTH); + /* 'lowest_stack' should be aligned on the register width boundary */ + sp = ALIGN(sp, sizeof(unsigned long)); if (sp < current->lowest_stack && sp >= (unsigned long)task_stack_page(current) + sizeof(unsigned long)) { diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index 5f7df50cfe7a..952e46876329 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -33,6 +33,8 @@ gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ += -DSTACKLEAK_PLUGIN gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ += -fplugin-arg-stackleak_plugin-track-min-size=$(CONFIG_STACKLEAK_TRACK_MIN_SIZE) +gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ + += -fplugin-arg-stackleak_plugin-arch=$(SRCARCH) ifdef CONFIG_GCC_PLUGIN_STACKLEAK DISABLE_STACKLEAK_PLUGIN += -fplugin-arg-stackleak_plugin-disable endif diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index cc75eeba0be1..a18b0d4af456 100644 --- a/scripts/gcc-plugins/stackleak_plugin.c +++ b/scripts/gcc-plugins/stackleak_plugin.c @@ -20,7 +20,7 @@ * * Debugging: * - use fprintf() to stderr, debug_generic_expr(), debug_gimple_stmt(), - * print_rtl() and print_simple_rtl(); + * print_rtl_single() and debug_rtx(); * - add "-fdump-tree-all -fdump-rtl-all" to the plugin CFLAGS in * Makefile.gcc-plugins to see the verbose dumps of the gcc passes; * - use gcc -E to understand the preprocessing shenanigans; @@ -32,6 +32,7 @@ __visible int plugin_is_GPL_compatible; static int track_frame_size = -1; +static bool build_for_x86 = false; static const char track_function[] = "stackleak_track_stack"; /* @@ -43,32 +44,31 @@ static GTY(()) tree track_function_decl; static struct plugin_info stackleak_plugin_info = { .version = "201707101337", .help = "track-min-size=nn\ttrack stack for functions with a stack frame size >= nn bytes\n" + "arch=target_arch\tspecify target build arch\n" "disable\t\tdo not activate the plugin\n" }; -static void stackleak_add_track_stack(gimple_stmt_iterator *gsi, bool after) +static void add_stack_tracking_gcall(gimple_stmt_iterator *gsi, bool after) { gimple stmt; - gcall *stackleak_track_stack; + gcall *gimple_call; cgraph_node_ptr node; basic_block bb; - /* Insert call to void stackleak_track_stack(void) */ + /* Insert calling stackleak_track_stack() */ stmt = gimple_build_call(track_function_decl, 0); - stackleak_track_stack = as_a_gcall(stmt); - if (after) { - gsi_insert_after(gsi, stackleak_track_stack, - GSI_CONTINUE_LINKING); - } else { - gsi_insert_before(gsi, stackleak_track_stack, GSI_SAME_STMT); - } + gimple_call = as_a_gcall(stmt); + if (after) + gsi_insert_after(gsi, gimple_call, GSI_CONTINUE_LINKING); + else + gsi_insert_before(gsi, gimple_call, GSI_SAME_STMT); /* Update the cgraph */ - bb = gimple_bb(stackleak_track_stack); + bb = gimple_bb(gimple_call); node = cgraph_get_create_node(track_function_decl); gcc_assert(node); cgraph_create_edge(cgraph_get_node(current_function_decl), node, - stackleak_track_stack, bb->count, + gimple_call, bb->count, compute_call_stmt_bb_frequency(current_function_decl, bb)); } @@ -85,6 +85,79 @@ static bool is_alloca(gimple stmt) return false; } +static tree get_current_stack_pointer_decl(void) +{ + varpool_node_ptr node; + + FOR_EACH_VARIABLE(node) { + tree var = NODE_DECL(node); + tree name = DECL_NAME(var); + + if (DECL_NAME_LENGTH(var) != sizeof("current_stack_pointer") - 1) + continue; + + if (strcmp(IDENTIFIER_POINTER(name), "current_stack_pointer")) + continue; + + return var; + } + + return NULL_TREE; +} + +static void add_stack_tracking_gasm(gimple_stmt_iterator *gsi, bool after) +{ + gasm *asm_call = NULL; + tree sp_decl, input; + vec *inputs = NULL; + + /* 'no_caller_saved_registers' is currently supported only for x86 */ + gcc_assert(build_for_x86); + + /* + * Insert calling stackleak_track_stack() in asm: + * asm volatile("call stackleak_track_stack" + * :: "r" (current_stack_pointer)) + * Use ASM_CALL_CONSTRAINT trick from arch/x86/include/asm/asm.h. + * This constraint is taken into account during gcc shrink-wrapping + * optimization. It is needed to be sure that stackleak_track_stack() + * call is inserted after the prologue of the containing function, + * when the stack frame is prepared. + */ + sp_decl = get_current_stack_pointer_decl(); + if (sp_decl == NULL_TREE) { + add_stack_tracking_gcall(gsi, after); + return; + } + input = build_tree_list(NULL_TREE, build_const_char_string(2, "r")); + input = chainon(NULL_TREE, build_tree_list(input, sp_decl)); + vec_safe_push(inputs, input); + asm_call = gimple_build_asm_vec("call stackleak_track_stack", + inputs, NULL, NULL, NULL); + gimple_asm_set_volatile(asm_call, true); + if (after) + gsi_insert_after(gsi, asm_call, GSI_CONTINUE_LINKING); + else + gsi_insert_before(gsi, asm_call, GSI_SAME_STMT); + update_stmt(asm_call); +} + +static void add_stack_tracking(gimple_stmt_iterator *gsi, bool after) +{ + /* + * The 'no_caller_saved_registers' attribute is used for + * stackleak_track_stack(). If the compiler supports this attribute for + * the target arch, we can add calling stackleak_track_stack() in asm. + * That improves performance: we avoid useless operations with the + * caller-saved registers in the functions from which we will remove + * stackleak_track_stack() call during the stackleak_cleanup pass. + */ + if (lookup_attribute_spec(get_identifier("no_caller_saved_registers"))) + add_stack_tracking_gasm(gsi, after); + else + add_stack_tracking_gcall(gsi, after); +} + /* * Work with the GIMPLE representation of the code. Insert the * stackleak_track_stack() call after alloca() and into the beginning @@ -94,7 +167,7 @@ static unsigned int stackleak_instrument_execute(void) { basic_block bb, entry_bb; bool prologue_instrumented = false, is_leaf = true; - gimple_stmt_iterator gsi; + gimple_stmt_iterator gsi = { 0 }; /* * ENTRY_BLOCK_PTR is a basic block which represents possible entry @@ -123,7 +196,7 @@ static unsigned int stackleak_instrument_execute(void) continue; /* Insert stackleak_track_stack() call after alloca() */ - stackleak_add_track_stack(&gsi, true); + add_stack_tracking(&gsi, true); if (bb == entry_bb) prologue_instrumented = true; } @@ -168,7 +241,7 @@ static unsigned int stackleak_instrument_execute(void) bb = single_succ(ENTRY_BLOCK_PTR_FOR_FN(cfun)); } gsi = gsi_after_labels(bb); - stackleak_add_track_stack(&gsi, false); + add_stack_tracking(&gsi, false); return 0; } @@ -182,21 +255,10 @@ static bool large_stack_frame(void) #endif } -/* - * Work with the RTL representation of the code. - * Remove the unneeded stackleak_track_stack() calls from the functions - * which don't call alloca() and don't have a large enough stack frame size. - */ -static unsigned int stackleak_cleanup_execute(void) +static void remove_stack_tracking_gcall(void) { rtx_insn *insn, *next; - if (cfun->calls_alloca) - return 0; - - if (large_stack_frame()) - return 0; - /* * Find stackleak_track_stack() calls. Loop through the chain of insns, * which is an RTL representation of the code for a function. @@ -257,6 +319,84 @@ static unsigned int stackleak_cleanup_execute(void) } #endif } +} + +static bool remove_stack_tracking_gasm(void) +{ + bool removed = false; + rtx_insn *insn, *next; + + /* 'no_caller_saved_registers' is currently supported only for x86 */ + gcc_assert(build_for_x86); + + /* + * Find stackleak_track_stack() asm calls. Loop through the chain of + * insns, which is an RTL representation of the code for a function. + * + * The example of a matching insn: + * (insn 11 5 12 2 (parallel [ (asm_operands/v + * ("call stackleak_track_stack") ("") 0 + * [ (reg/v:DI 7 sp [ current_stack_pointer ]) ] + * [ (asm_input:DI ("r")) ] []) + * (clobber (reg:CC 17 flags)) ]) -1 (nil)) + */ + for (insn = get_insns(); insn; insn = next) { + rtx body; + + next = NEXT_INSN(insn); + + /* Check the expression code of the insn */ + if (!NONJUMP_INSN_P(insn)) + continue; + + /* + * Check the expression code of the insn body, which is an RTL + * Expression (RTX) describing the side effect performed by + * that insn. + */ + body = PATTERN(insn); + + if (GET_CODE(body) != PARALLEL) + continue; + + body = XVECEXP(body, 0, 0); + + if (GET_CODE(body) != ASM_OPERANDS) + continue; + + if (strcmp(ASM_OPERANDS_TEMPLATE(body), + "call stackleak_track_stack")) { + continue; + } + + delete_insn_and_edges(insn); + gcc_assert(!removed); + removed = true; + } + + return removed; +} + +/* + * Work with the RTL representation of the code. + * Remove the unneeded stackleak_track_stack() calls from the functions + * which don't call alloca() and don't have a large enough stack frame size. + */ +static unsigned int stackleak_cleanup_execute(void) +{ + bool removed = false; + + if (cfun->calls_alloca) + return 0; + + if (large_stack_frame()) + return 0; + + if (lookup_attribute_spec(get_identifier("no_caller_saved_registers"))) + removed = remove_stack_tracking_gasm(); + + if (!removed) + remove_stack_tracking_gcall(); return 0; } @@ -392,6 +532,15 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, plugin_name, argv[i].key, argv[i].value); return 1; } + } else if (!strcmp(argv[i].key, "arch")) { + if (!argv[i].value) { + error(G_("no value supplied for option '-fplugin-arg-%s-%s'"), + plugin_name, argv[i].key); + return 1; + } + + if (!strcmp(argv[i].value, "x86")) + build_for_x86 = true; } else { error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); 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Wed, 24 Jun 2020 05:34:47 -0700 (PDT) From: Alexander Popov To: Kees Cook , Jann Horn , Emese Revfy , Miguel Ojeda , Masahiro Yamada , Michal Marek , Andrew Morton , Masahiro Yamada , Thiago Jung Bauermann , Luis Chamberlain , Jessica Yu , Sven Schnelle , Iurii Zaikin , Catalin Marinas , Will Deacon , Vincenzo Frascino , Thomas Gleixner , Peter Collingbourne , Naohiro Aota , Alexander Monakov , Mathias Krause , PaX Team , Brad Spengler , Laura Abbott , Florian Weimer , Alexander Popov , kernel-hardening@lists.openwall.com, linux-kbuild@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, gcc@gcc.gnu.org Cc: notify@kernel.org Subject: [PATCH v2 5/5] gcc-plugins/stackleak: Add 'verbose' plugin parameter Date: Wed, 24 Jun 2020 15:33:30 +0300 Message-Id: <20200624123330.83226-6-alex.popov@linux.com> X-Mailer: git-send-email 2.25.4 In-Reply-To: <20200624123330.83226-1-alex.popov@linux.com> References: <20200624123330.83226-1-alex.popov@linux.com> MIME-Version: 1.0 Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org Add 'verbose' plugin parameter for stackleak gcc plugin. It can be used for printing additional info about the kernel code instrumentation. For using it add the following to scripts/Makefile.gcc-plugins: gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_STACKLEAK) \ += -fplugin-arg-stackleak_plugin-verbose Signed-off-by: Alexander Popov --- scripts/gcc-plugins/stackleak_plugin.c | 47 +++++++++++++++++++++++--- 1 file changed, 42 insertions(+), 5 deletions(-) diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index a18b0d4af456..48e141e07956 100644 --- a/scripts/gcc-plugins/stackleak_plugin.c +++ b/scripts/gcc-plugins/stackleak_plugin.c @@ -34,6 +34,8 @@ __visible int plugin_is_GPL_compatible; static int track_frame_size = -1; static bool build_for_x86 = false; static const char track_function[] = "stackleak_track_stack"; +static bool disable = false; +static bool verbose = false; /* * Mark these global variables (roots) for gcc garbage collector since @@ -46,6 +48,7 @@ static struct plugin_info stackleak_plugin_info = { .help = "track-min-size=nn\ttrack stack for functions with a stack frame size >= nn bytes\n" "arch=target_arch\tspecify target build arch\n" "disable\t\tdo not activate the plugin\n" + "verbose\t\tprint info about the instrumentation\n" }; static void add_stack_tracking_gcall(gimple_stmt_iterator *gsi, bool after) @@ -102,6 +105,10 @@ static tree get_current_stack_pointer_decl(void) return var; } + if (verbose) { + fprintf(stderr, "stackleak: missing current_stack_pointer in %s()\n", + DECL_NAME_POINTER(current_function_decl)); + } return NULL_TREE; } @@ -195,6 +202,11 @@ static unsigned int stackleak_instrument_execute(void) if (!is_alloca(stmt)) continue; + if (verbose) { + fprintf(stderr, "stackleak: be careful, alloca() in %s()\n", + DECL_NAME_POINTER(current_function_decl)); + } + /* Insert stackleak_track_stack() call after alloca() */ add_stack_tracking(&gsi, true); if (bb == entry_bb) @@ -384,13 +396,31 @@ static bool remove_stack_tracking_gasm(void) */ static unsigned int stackleak_cleanup_execute(void) { + const char *fn = DECL_NAME_POINTER(current_function_decl); bool removed = false; - if (cfun->calls_alloca) + /* + * Leave stack tracking in functions that call alloca(). + * Additional case: + * gcc before version 7 called allocate_dynamic_stack_space() from + * expand_stack_vars() for runtime alignment of constant-sized stack + * variables. That caused cfun->calls_alloca to be set for functions + * that in fact don't use alloca(). + * For more info see gcc commit 7072df0aae0c59ae437e. + * Let's leave such functions instrumented as well. + */ + if (cfun->calls_alloca) { + if (verbose) + fprintf(stderr, "stackleak: instrument %s(): calls_alloca\n", fn); return 0; + } - if (large_stack_frame()) + /* Leave stack tracking in functions with large stack frame */ + if (large_stack_frame()) { + if (verbose) + fprintf(stderr, "stackleak: instrument %s()\n", fn); return 0; + } if (lookup_attribute_spec(get_identifier("no_caller_saved_registers"))) removed = remove_stack_tracking_gasm(); @@ -516,9 +546,6 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, /* Parse the plugin arguments */ for (i = 0; i < argc; i++) { - if (!strcmp(argv[i].key, "disable")) - return 0; - if (!strcmp(argv[i].key, "track-min-size")) { if (!argv[i].value) { error(G_("no value supplied for option '-fplugin-arg-%s-%s'"), @@ -541,6 +568,10 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, if (!strcmp(argv[i].value, "x86")) build_for_x86 = true; + } else if (!strcmp(argv[i].key, "disable")) { + disable = true; + } else if (!strcmp(argv[i].key, "verbose")) { + verbose = true; } else { error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key); @@ -548,6 +579,12 @@ __visible int plugin_init(struct plugin_name_args *plugin_info, } } + if (disable) { + if (verbose) + fprintf(stderr, "stackleak: disabled for this translation unit\n"); + return 0; + } + /* Give the information about the plugin */ register_callback(plugin_name, PLUGIN_INFO, NULL, &stackleak_plugin_info);