From patchwork Wed Jan 22 21:21:38 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mark Brown X-Patchwork-Id: 11346413 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 32CEC139A for ; Wed, 22 Jan 2020 21:22:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 074A624673 for ; Wed, 22 Jan 2020 21:22:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579728163; bh=oyMXO1tKgZA7NWg60KyB1tdGu+wk6FfkL/6t66l5wkY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=KKONNEHnOd6TY4giTEyeg5nCx3+jlJznykvMGem2IlKX4S36IfJcRY6hQtmVuJlPe mLR1IVJzZY8El3wSJSGIy9LYZJcbWcFbuTUD1C4Q6hWqvOnyrdW8I0Fj3M6yXDd+jW P4YM9POSYCYAJP+a16CCDHFrDouXSFBIAaqY58zw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729271AbgAVVWJ (ORCPT ); Wed, 22 Jan 2020 16:22:09 -0500 Received: from foss.arm.com ([217.140.110.172]:60910 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728904AbgAVVWI (ORCPT ); Wed, 22 Jan 2020 16:22:08 -0500 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 D323711FB; Wed, 22 Jan 2020 13:22:07 -0800 (PST) Received: from localhost (unknown [10.37.6.21]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F34753F52E; Wed, 22 Jan 2020 13:22:06 -0800 (PST) From: Mark Brown To: Catalin Marinas , Will Deacon Cc: Alexander Viro , Paul Elliott , Peter Zijlstra , Yu-cheng Yu , Amit Kachhap , Vincenzo Frascino , Marc Zyngier , Eugene Syromiatnikov , Szabolcs Nagy , "H . J . Lu " , Andrew Jones , Kees Cook , Arnd Bergmann , Jann Horn , Richard Henderson , =?utf-8?q?Kristina_Mart?= =?utf-8?q?=C5=A1enko?= , Thomas Gleixner , Florian Weimer , Sudakshina Das , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, Dave Martin , Mark Brown Subject: [PATCH v5 06/12] arm64: elf: Enable BTI at exec based on ELF program properties Date: Wed, 22 Jan 2020 21:21:38 +0000 Message-Id: <20200122212144.6409-7-broonie@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200122212144.6409-1-broonie@kernel.org> References: <20200122212144.6409-1-broonie@kernel.org> MIME-Version: 1.0 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Dave Martin For BTI protection to be as comprehensive as possible, it is desirable to have BTI enabled from process startup. If this is not done, the process must use mprotect() to enable BTI for each of its executable mappings, but this is painful to do in the libc startup code. It's simpler and more sound to have the kernel do it instead. To this end, detect BTI support in the executable (or ELF interpreter, as appropriate), via the NT_GNU_PROGRAM_PROPERTY_TYPE_0 note, and tweak the initial prot flags for the process' executable pages to include PROT_BTI as appropriate. Signed-off-by: Dave Martin Reviewed-by: Catalin Marinas Signed-off-by: Mark Brown Reported-by: kbuild test robot --- arch/arm64/Kconfig | 3 +++ arch/arm64/include/asm/elf.h | 50 ++++++++++++++++++++++++++++++++++++ arch/arm64/kernel/process.c | 19 ++++++++++++++ include/linux/elf.h | 6 ++++- include/uapi/linux/elf.h | 6 +++++ 5 files changed, 83 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 39292a0fc603..ea3a5150f5f6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -9,6 +9,7 @@ config ARM64 select ACPI_MCFG if (ACPI && PCI) select ACPI_SPCR_TABLE if ACPI select ACPI_PPTT if ACPI + select ARCH_BINFMT_ELF_STATE select ARCH_CLOCKSOURCE_DATA select ARCH_HAS_DEBUG_VIRTUAL select ARCH_HAS_DEVMEM_IS_ALLOWED @@ -33,6 +34,7 @@ config ARM64 select ARCH_HAS_SYSCALL_WRAPPER select ARCH_HAS_TEARDOWN_DMA_OPS if IOMMU_SUPPORT select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST + select ARCH_HAVE_ELF_PROT select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_INLINE_READ_LOCK if !PREEMPT select ARCH_INLINE_READ_LOCK_BH if !PREEMPT @@ -62,6 +64,7 @@ config ARM64 select ARCH_INLINE_SPIN_UNLOCK_IRQRESTORE if !PREEMPT select ARCH_KEEP_MEMBLOCK select ARCH_USE_CMPXCHG_LOCKREF + select ARCH_USE_GNU_PROPERTY if BINFMT_ELF select ARCH_USE_QUEUED_RWLOCKS select ARCH_USE_QUEUED_SPINLOCKS select ARCH_SUPPORTS_MEMORY_FAILURE diff --git a/arch/arm64/include/asm/elf.h b/arch/arm64/include/asm/elf.h index b618017205a3..fca3a48e9db5 100644 --- a/arch/arm64/include/asm/elf.h +++ b/arch/arm64/include/asm/elf.h @@ -114,7 +114,11 @@ #ifndef __ASSEMBLY__ +#include #include +#include +#include +#include #include /* for signal_minsigstksz, used by ARCH_DLINFO */ typedef unsigned long elf_greg_t; @@ -224,6 +228,52 @@ extern int aarch32_setup_additional_pages(struct linux_binprm *bprm, #endif /* CONFIG_COMPAT */ +struct arch_elf_state { + int flags; +}; + +#define ARM64_ELF_BTI (1 << 0) + +#define INIT_ARCH_ELF_STATE { \ + .flags = 0, \ +} + +static inline int arch_parse_elf_property(u32 type, const void *data, + size_t datasz, bool compat, + struct arch_elf_state *arch) +{ + /* No known properties for AArch32 yet */ + if (IS_ENABLED(CONFIG_COMPAT) && compat) + return 0; + + if (type == GNU_PROPERTY_AARCH64_FEATURE_1_AND) { + const u32 *p = data; + + if (datasz != sizeof(*p)) + return -ENOEXEC; + + if (IS_ENABLED(CONFIG_ARM64_BTI) && + (*p & GNU_PROPERTY_AARCH64_FEATURE_1_BTI)) + arch->flags |= ARM64_ELF_BTI; + } + + return 0; +} + +static inline int arch_elf_pt_proc(void *ehdr, void *phdr, + struct file *f, bool is_interp, + struct arch_elf_state *state) +{ + return 0; +} + +static inline int arch_check_elf(void *ehdr, bool has_interp, + void *interp_ehdr, + struct arch_elf_state *state) +{ + return 0; +} + #endif /* !__ASSEMBLY__ */ #endif diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 71f788cd2b18..37c508f409ac 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -11,6 +11,7 @@ #include #include +#include #include #include #include @@ -18,6 +19,7 @@ #include #include #include +#include #include #include #include @@ -649,3 +651,20 @@ asmlinkage void __sched arm64_preempt_schedule_irq(void) if (static_branch_likely(&arm64_const_caps_ready)) preempt_schedule_irq(); } + +#ifdef CONFIG_BINFMT_ELF +int arch_elf_adjust_prot(int prot, const struct arch_elf_state *state, + bool has_interp, bool is_interp) +{ + if (is_interp != has_interp) + return prot; + + if (!(state->flags & ARM64_ELF_BTI)) + return prot; + + if (prot & PROT_EXEC) + prot |= PROT_BTI; + + return prot; +} +#endif diff --git a/include/linux/elf.h b/include/linux/elf.h index 1b6e8955c597..5d5b0321da0b 100644 --- a/include/linux/elf.h +++ b/include/linux/elf.h @@ -63,7 +63,11 @@ extern int elf_coredump_extra_notes_size(void); extern int elf_coredump_extra_notes_write(struct coredump_params *cprm); #endif -/* NT_GNU_PROPERTY_TYPE_0 header */ +/* + * NT_GNU_PROPERTY_TYPE_0 header: + * Keep this internal until/unless there is an agreed UAPI definition. + * pr_type values (GNU_PROPERTY_*) are public and defined in the UAPI header. + */ struct gnu_property { u32 pr_type; u32 pr_datasz; diff --git a/include/uapi/linux/elf.h b/include/uapi/linux/elf.h index 20900f4496b7..c6dd0215482e 100644 --- a/include/uapi/linux/elf.h +++ b/include/uapi/linux/elf.h @@ -448,4 +448,10 @@ typedef struct elf64_note { Elf64_Word n_type; /* Content type */ } Elf64_Nhdr; +/* .note.gnu.property types for EM_AARCH64: */ +#define GNU_PROPERTY_AARCH64_FEATURE_1_AND 0xc0000000 + +/* Bits for GNU_PROPERTY_AARCH64_FEATURE_1_BTI */ +#define GNU_PROPERTY_AARCH64_FEATURE_1_BTI (1U << 0) + #endif /* _UAPI_LINUX_ELF_H */