From patchwork Fri Jul 20 21:41:54 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laura Abbott X-Patchwork-Id: 10538445 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id E29EF6029B for ; Fri, 20 Jul 2018 21:42:34 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D9FFD29259 for ; Fri, 20 Jul 2018 21:42:34 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CDD312925F; Fri, 20 Jul 2018 21:42:34 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id AE0B229259 for ; Fri, 20 Jul 2018 21:42:33 +0000 (UTC) Received: (qmail 15867 invoked by uid 550); 20 Jul 2018 21:42:17 -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 15674 invoked from network); 20 Jul 2018 21:42:16 -0000 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; bh=/Ld8wjs7KxCcl4zSvDzg4dEg33msapg+r54ggPPmxJE=; b=ezsE9DnidnVdJZjpFFjfeilFw/OkbGyfCzTm0fNzwcwkI9rq/inwonDdMUJZh7MIbV xa9E84gC7LfcclGtNqnafvIeHk8kjEloCf3sEL89UO/Xt20wXy4EnYq/yOC3cQ6czL0L DIwQCiZXXaufQieZVlrAq8Wi2LusHsgHkwiES1SU6yRyQEROGEFOX4BTxZn+zD6UDsvJ CKKMfp5e7/UuJ8kzJ5rxopbJCEf8mB1DrhMrHNO++TrAsqrtPHcu74jpoYcRyI57DQOQ Tq0ICQJf4Ly1eAYs1wTog39DWwCFEKHPSGezcwmGHstFE42qqbKhaNpaOE3ILVLjw2U2 z/eA== X-Gm-Message-State: AOUpUlGItl+DV4TJ3uagc9fjsu8z+7e5Zn5K+NpVVCCP5OlIuRWJFab+ dV2VR5ntwoS3ESSh62Xw0lRzsA== X-Google-Smtp-Source: AAOMgpdx042QU1GVq03zrlVrCyYBd8zFqUiWqivAoWS4XAt63fvec3sIQj334MqaUS78TFAVLa0QNg== X-Received: by 2002:ac8:42b:: with SMTP id v43-v6mr3455714qtg.319.1532122924952; Fri, 20 Jul 2018 14:42:04 -0700 (PDT) From: Laura Abbott To: Alexander Popov , Kees Cook , Mark Rutland , Ard Biesheuvel Cc: Laura Abbott , kernel-hardening@lists.openwall.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Will Deacon , Catalin Marinas Subject: [PATCHv3 2/2] arm64: Add support for STACKLEAK gcc plugin Date: Fri, 20 Jul 2018 14:41:54 -0700 Message-Id: <20180720214154.2940-3-labbott@redhat.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180720214154.2940-1-labbott@redhat.com> References: <20180720214154.2940-1-labbott@redhat.com> X-Virus-Scanned: ClamAV using ClamSMTP This adds support for the STACKLEAK gcc plugin to arm64 by implementing stackleak_check_alloca(), based heavily on the x86 version, and adding the two helpers used by the stackleak common code: current_top_of_stack() and on_thread_stack(). The stack erasure calls are made at syscall returns. Additionally, this disables the plugin in hypervisor and EFI stub code, which are out of scope for the protection. Reviewed-by: Mark Rutland Reviewed-by: Kees Cook Signed-off-by: Laura Abbott Acked-by: Alexander Popov --- v3: Actual commit text courtesy of Kees. A comment explaining why we panic --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/processor.h | 15 +++++++++++++++ arch/arm64/kernel/entry.S | 7 +++++++ arch/arm64/kernel/process.c | 22 ++++++++++++++++++++++ arch/arm64/kvm/hyp/Makefile | 3 ++- drivers/firmware/efi/libstub/Makefile | 3 ++- 6 files changed, 49 insertions(+), 2 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 42c090cf0292..216d36a49ab5 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -96,6 +96,7 @@ config ARM64 select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT select HAVE_ARCH_SECCOMP_FILTER + select HAVE_ARCH_STACKLEAK select HAVE_ARCH_THREAD_STRUCT_WHITELIST select HAVE_ARCH_TRACEHOOK select HAVE_ARCH_TRANSPARENT_HUGEPAGE diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index a73ae1e49200..0061450a793b 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -266,5 +266,20 @@ extern void __init minsigstksz_setup(void); #define SVE_SET_VL(arg) sve_set_current_vl(arg) #define SVE_GET_VL() sve_get_current_vl() +/* + * For CONFIG_GCC_PLUGIN_STACKLEAK + * + * These need to be macros because otherwise we get stuck in a nightmare + * of header definitions for the use of task_stack_page. + */ + +#define current_top_of_stack() \ +({ \ + struct stack_info _info; \ + BUG_ON(!on_accessible_stack(current, current_stack_pointer, &_info)); \ + _info.high; \ +}) +#define on_thread_stack() (on_task_stack(current, current_stack_pointer, NULL)) + #endif /* __ASSEMBLY__ */ #endif /* __ASM_PROCESSOR_H */ diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 28ad8799406f..67d12016063d 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -431,6 +431,11 @@ tsk .req x28 // current thread_info .text + .macro stackleak_erase +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK + bl stackleak_erase +#endif + .endm /* * Exception vectors. */ @@ -910,6 +915,7 @@ ret_fast_syscall: and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending enable_step_tsk x1, x2 + stackleak_erase kernel_exit 0 ret_fast_syscall_trace: enable_daif @@ -936,6 +942,7 @@ ret_to_user: cbnz x2, work_pending finish_ret_to_user: enable_step_tsk x1, x2 + stackleak_erase kernel_exit 0 ENDPROC(ret_to_user) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index e10bc363f533..f0ad00fb6a71 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -493,3 +493,25 @@ void arch_setup_new_exec(void) { current->mm->context.flags = is_compat_task() ? MMCF_AARCH32 : 0; } + +#ifdef CONFIG_GCC_PLUGIN_STACKLEAK +void __used stackleak_check_alloca(unsigned long size) +{ + unsigned long stack_left; + unsigned long current_sp = current_stack_pointer; + struct stack_info info; + + BUG_ON(!on_accessible_stack(current, current_sp, &info)); + + stack_left = current_sp - info.low; + + /* + * There's a good chance we're almost out of stack space if this + * is true. Using panic() over BUG() is more likely to give + * reliable debugging output. + */ + if (size >= stack_left) + panic("alloca() over the kernel stack boundary\n"); +} +EXPORT_SYMBOL(stackleak_check_alloca); +#endif diff --git a/arch/arm64/kvm/hyp/Makefile b/arch/arm64/kvm/hyp/Makefile index 4313f7475333..2fabc2dc1966 100644 --- a/arch/arm64/kvm/hyp/Makefile +++ b/arch/arm64/kvm/hyp/Makefile @@ -3,7 +3,8 @@ # Makefile for Kernel-based Virtual Machine module, HYP part # -ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING +ccflags-y += -fno-stack-protector -DDISABLE_BRANCH_PROFILING \ + $(DISABLE_STACKLEAK_PLUGIN) KVM=../../../../virt/kvm diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile index a34e9290a699..25dd2a14560d 100644 --- a/drivers/firmware/efi/libstub/Makefile +++ b/drivers/firmware/efi/libstub/Makefile @@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \ -D__NO_FORTIFY \ $(call cc-option,-ffreestanding) \ - $(call cc-option,-fno-stack-protector) + $(call cc-option,-fno-stack-protector) \ + $(DISABLE_STACKLEAK_PLUGIN) GCOV_PROFILE := n KASAN_SANITIZE := n