From patchwork Tue Dec 24 05:55:41 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Russell Currey X-Patchwork-Id: 11309101 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 843FE15AB for ; Tue, 24 Dec 2019 05:56:16 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id B6DAE20718 for ; Tue, 24 Dec 2019 05:56:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=russell.cc header.i=@russell.cc header.b="eHLEmCQ7"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="Do92WA0M" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B6DAE20718 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=russell.cc Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-17515-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 20012 invoked by uid 550); 24 Dec 2019 05:56:09 -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 19896 invoked from network); 24 Dec 2019 05:56:08 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=russell.cc; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; s=fm3; bh=/ZAqtJdy+ln43 ioqFQJBYAV6EX+9TBgNroal6pRoyiA=; b=eHLEmCQ7ftwOduXWG7E5KB3TYj48d Z2dQiqLAAZmDIfCgqpdc2aS2mu+rQ2z6PLq+XYNc9diFsNjqHdBayz6p+An8UfoF czoGB/PpWP29dl10Qcz56zJ7FgH2WMPRAQt0pUEnmgiX7jeuEdTgFzBYU+fL0+8u YfGZcMtKBlxNEQ0xnQmVpIMl/UZndWwPZrEIRoydU+5G/3TEHVla5wqPpn6Kw+l6 bKivtbXlMEhzKbnZJryUODf9KuDY6y2QLxftceEo63ARFHge4/YucWk4oO7YYhHi N3GHMyUD5J/KrrP02OoB0Gdr0i+vGJ5qWwRGcMJfJK0v2RRpqqXlIRbbA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :in-reply-to:message-id:mime-version:references:subject:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm1; bh=/ZAqtJdy+ln43ioqFQJBYAV6EX+9TBgNroal6pRoyiA=; b=Do92WA0M 93EFff069P0gAjD/+Cu/Fv7+7sesresmXxESFxKwcs4Ymdaau352pSlJdCwD6M11 Xo6c760BAfA4MKjUTSrm5XY9HiIjLOLg9Ws2DM8QvQ8QhVtP4oZ4xy+TNwLYfLee hrZM09F8070WA4+A0y6ZXFFxT5+aOhaydomRqjyWltQS4Nq7kIxPgdjgX3YkZW3i ZUqr41G7UN2hrUA6SUzzCU9eagXu+0ks/4b7vlM0mCFGKPEHP/q3UlcPsD14UNi0 pC3J613TeVsKVP0hiDixbB8HSXs0EdhwFy0YdxaJPe0xpUZAqzlhfTkR1AB/trT7 qi7LPOZ/Y/lXCQ== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedufedrvddvuddgieduucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucgfrhhlucfvnfffucdlfedtmdenucfjughrpefhvf fufffkofgjfhgggfestdekredtredttdenucfhrhhomheptfhushhsvghllhcuvehurhhr vgihuceorhhushgtuhhrsehruhhsshgvlhhlrdgttgeqnecukfhppeduvddvrdelledrke dvrddutdenucfrrghrrghmpehmrghilhhfrhhomheprhhushgtuhhrsehruhhsshgvlhhl rdgttgenucevlhhushhtvghrufhiiigvpedt X-ME-Proxy: From: Russell Currey To: linuxppc-dev@lists.ozlabs.org Cc: Russell Currey , christophe.leroy@c-s.fr, joel@jms.id.au, mpe@ellerman.id.au, ajd@linux.ibm.com, dja@axtens.net, npiggin@gmail.com, kernel-hardening@lists.openwall.com Subject: [PATCH v6 1/5] powerpc/mm: Implement set_memory() routines Date: Tue, 24 Dec 2019 16:55:41 +1100 Message-Id: <20191224055545.178462-2-ruscur@russell.cc> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191224055545.178462-1-ruscur@russell.cc> References: <20191224055545.178462-1-ruscur@russell.cc> MIME-Version: 1.0 The set_memory_{ro/rw/nx/x}() functions are required for STRICT_MODULE_RWX, and are generally useful primitives to have. This implementation is designed to be completely generic across powerpc's many MMUs. It's possible that this could be optimised to be faster for specific MMUs, but the focus is on having a generic and safe implementation for now. This implementation does not handle cases where the caller is attempting to change the mapping of the page it is executing from, or if another CPU is concurrently using the page being altered. These cases likely shouldn't happen, but a more complex implementation with MMU-specific code could safely handle them, so that is left as a TODO for now. Signed-off-by: Russell Currey --- arch/powerpc/Kconfig | 1 + arch/powerpc/include/asm/set_memory.h | 32 +++++++++++ arch/powerpc/mm/Makefile | 1 + arch/powerpc/mm/pageattr.c | 83 +++++++++++++++++++++++++++ 4 files changed, 117 insertions(+) create mode 100644 arch/powerpc/include/asm/set_memory.h create mode 100644 arch/powerpc/mm/pageattr.c diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 1ec34e16ed65..f0b9b47b5353 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -133,6 +133,7 @@ config PPC select ARCH_HAS_PTE_SPECIAL select ARCH_HAS_MEMBARRIER_CALLBACKS select ARCH_HAS_SCALED_CPUTIME if VIRT_CPU_ACCOUNTING_NATIVE && PPC_BOOK3S_64 + select ARCH_HAS_SET_MEMORY select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION) select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST select ARCH_HAS_UACCESS_FLUSHCACHE diff --git a/arch/powerpc/include/asm/set_memory.h b/arch/powerpc/include/asm/set_memory.h new file mode 100644 index 000000000000..5230ddb2fefd --- /dev/null +++ b/arch/powerpc/include/asm/set_memory.h @@ -0,0 +1,32 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_SET_MEMORY_H +#define _ASM_POWERPC_SET_MEMORY_H + +#define SET_MEMORY_RO 1 +#define SET_MEMORY_RW 2 +#define SET_MEMORY_NX 3 +#define SET_MEMORY_X 4 + +int change_memory_attr(unsigned long addr, int numpages, int action); + +static inline int set_memory_ro(unsigned long addr, int numpages) +{ + return change_memory_attr(addr, numpages, SET_MEMORY_RO); +} + +static inline int set_memory_rw(unsigned long addr, int numpages) +{ + return change_memory_attr(addr, numpages, SET_MEMORY_RW); +} + +static inline int set_memory_nx(unsigned long addr, int numpages) +{ + return change_memory_attr(addr, numpages, SET_MEMORY_NX); +} + +static inline int set_memory_x(unsigned long addr, int numpages) +{ + return change_memory_attr(addr, numpages, SET_MEMORY_X); +} + +#endif diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile index 5e147986400d..d0a0bcbc9289 100644 --- a/arch/powerpc/mm/Makefile +++ b/arch/powerpc/mm/Makefile @@ -20,3 +20,4 @@ obj-$(CONFIG_HIGHMEM) += highmem.o obj-$(CONFIG_PPC_COPRO_BASE) += copro_fault.o obj-$(CONFIG_PPC_PTDUMP) += ptdump/ obj-$(CONFIG_KASAN) += kasan/ +obj-$(CONFIG_ARCH_HAS_SET_MEMORY) += pageattr.o diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c new file mode 100644 index 000000000000..15d5fb04f531 --- /dev/null +++ b/arch/powerpc/mm/pageattr.c @@ -0,0 +1,83 @@ +// SPDX-License-Identifier: GPL-2.0 + +/* + * MMU-generic set_memory implementation for powerpc + * + * Copyright 2019, IBM Corporation. + */ + +#include +#include + +#include +#include +#include + + +/* + * Updates the attributes of a page in three steps: + * + * 1. invalidate the page table entry + * 2. flush the TLB + * 3. install the new entry with the updated attributes + * + * This is unsafe if the caller is attempting to change the mapping of the + * page it is executing from, or if another CPU is concurrently using the + * page being altered. + * + * TODO make the implementation resistant to this. + */ +static int __change_page_attr(pte_t *ptep, unsigned long addr, void *data) +{ + int action = *((int *)data); + pte_t pte_val; + + // invalidate the PTE so it's safe to modify + pte_val = ptep_get_and_clear(&init_mm, addr, ptep); + flush_tlb_kernel_range(addr, addr + PAGE_SIZE); + + // modify the PTE bits as desired, then apply + switch (action) { + case SET_MEMORY_RO: + pte_val = pte_wrprotect(pte_val); + break; + case SET_MEMORY_RW: + pte_val = pte_mkwrite(pte_val); + break; + case SET_MEMORY_NX: + pte_val = pte_exprotect(pte_val); + break; + case SET_MEMORY_X: + pte_val = pte_mkexec(pte_val); + break; + default: + WARN_ON(true); + return -EINVAL; + } + + set_pte_at(&init_mm, addr, ptep, pte_val); + + return 0; +} + +static int change_page_attr(pte_t *ptep, unsigned long addr, void *data) +{ + int ret; + + spin_lock(&init_mm.page_table_lock); + ret = __change_page_attr(ptep, addr, data); + spin_unlock(&init_mm.page_table_lock); + + return ret; +} + +int change_memory_attr(unsigned long addr, int numpages, int action) +{ + unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE); + unsigned long size = numpages * PAGE_SIZE; + + if (!numpages) + return 0; + + return apply_to_page_range(&init_mm, start, size, change_page_attr, &action); +}