From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39E4BC43381 for ; Wed, 13 Feb 2019 22:42:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3839222CC for ; Wed, 13 Feb 2019 22:42:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NpfP7YMb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2395156AbfBMWmN (ORCPT ); Wed, 13 Feb 2019 17:42:13 -0500 Received: from mail-wr1-f65.google.com ([209.85.221.65]:33450 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2395143AbfBMWmJ (ORCPT ); Wed, 13 Feb 2019 17:42:09 -0500 Received: by mail-wr1-f65.google.com with SMTP id i12so4422021wrw.0; Wed, 13 Feb 2019 14:42:06 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references:reply-to :mime-version:content-transfer-encoding; bh=cpONfAPk6wUEDmhM/mWi+eIpTzfniRXVZiNB9IzUGPk=; b=NpfP7YMbJknkb6E3ICzhLie/Ht/jwcXKzMye0lW81///ks6jBgvQ+e/FX0ZxxsCtov XKeBVlUVXI+U69qDLw2JRlDtAAIxgmqGtUNJFB8QMih7zWs/OLhYMnqgf2o33qQ3ExWR qaMPjJOz7wPhv300bJIAb+8aCIyxfD4C5Bjx/3Nv1UekkxpFvKbXF8pDM04Sk+h1Sjwk htAExuZfH2AFo0WF8glM+Tk0+CILfeKZYGKeFfpL95nHs6HWuZXX1RiBuNHXcM2q4NSV avo1AoEA1DLXHjvXfXygwMstbZR/DmPOQRkVB/bSl5SRRIFyJ9ryc19c52A/fCUkUuF0 PYfA== 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:reply-to:mime-version:content-transfer-encoding; bh=cpONfAPk6wUEDmhM/mWi+eIpTzfniRXVZiNB9IzUGPk=; b=IY+F6QPpx0X7PcU1vCJb31qqSHUEvCnt8JGDSlAcm6Wi8choKujNh2Om8Pr6qriuDh yn02Tu687xlMW7MWcMqy/k4IbwN/OPhzZGJYiGC+PcGexWTtv10ujL8rH0o9fC4j3584 XxrxeFg465pYJt+X8cCWDEiMlHj2b0ldVHticG90eU52n/MK9Npe2GeeS+/kjcwvaq7w e96yVzxwMdA7F5FBVlT+Kd8by3qhxGMTCQEcEyhqG7AfG/CUwP6eQf09hGyfDNS8JTFR m13NANH9UX1tfp1BEk8cpM7XgX2KvPIi+VhvUS6DRy8sTvW8J15qSIpjqqJts7ERmNC+ aEag== X-Gm-Message-State: AHQUAuai+7pnEpSCHQayOLkijjRy+Gguuo7ZPV9PaMVf0wIdYN6sg0b0 rOeMJIH44r+Qbl89DTSWvv0= X-Google-Smtp-Source: AHgI3Ia+VS3rKLWjGclsu+NoPrWW7oZG4FVXw0KNdR0DM973AqQZb9oxD5K7+pvCp25qY/FuXW3lEQ== X-Received: by 2002:adf:ba8e:: with SMTP id p14mr289178wrg.230.1550097726136; Wed, 13 Feb 2019 14:42:06 -0800 (PST) Received: from localhost.localdomain ([91.75.74.250]) by smtp.gmail.com with ESMTPSA id f196sm780810wme.36.2019.02.13.14.42.02 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 13 Feb 2019 14:42:05 -0800 (PST) From: Igor Stoppa X-Google-Original-From: Igor Stoppa Cc: Igor Stoppa , Andy Lutomirski , Nadav Amit , Matthew Wilcox , Peter Zijlstra , Kees Cook , Dave Hansen , Mimi Zohar , Thiago Jung Bauermann , Ahmed Soliman , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [RFC PATCH v5 03/12] __wr_after_init: Core and default arch Date: Thu, 14 Feb 2019 00:41:32 +0200 Message-Id: X-Mailer: git-send-email 2.19.1 In-Reply-To: References: Reply-To: Igor Stoppa MIME-Version: 1.0 Content-Transfer-Encoding: 8bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The patch provides: - the core functionality for write-rare after init for statically allocated data, based on code from Matthew Wilcox - the default implementation for generic architecture A specific architecture can override one or more of the default functions. The core (API) functions are: - wr_memset(): write rare counterpart of memset() - wr_memcpy(): write rare counterpart of memcpy() - wr_assign(): write rare counterpart of the assignment ('=') operator - wr_rcu_assign_pointer(): write rare counterpart of rcu_assign_pointer() In case either the selected architecture doesn't support write rare after init, or the functionality is disabled, the write rare functions will resolve into their non-write rare counterpart: - memset() - memcpy() - assignment operator - rcu_assign_pointer() For code that can be either link as module or as built-in (ex: device driver init function), it is not possible to tell upfront what will be the case. For this scenario if the functions are called during system init, they will automatically choose, at runtime, to go through the fast path of non-write rare. Should they be invoked later, during module init, they will use the write-rare path. Signed-off-by: Igor Stoppa CC: Andy Lutomirski CC: Nadav Amit CC: Matthew Wilcox CC: Peter Zijlstra CC: Kees Cook CC: Dave Hansen CC: Mimi Zohar CC: Thiago Jung Bauermann CC: Ahmed Soliman CC: linux-integrity@vger.kernel.org CC: kernel-hardening@lists.openwall.com CC: linux-mm@kvack.org CC: linux-kernel@vger.kernel.org --- arch/Kconfig | 7 ++ include/linux/prmem.h (new) | 70 ++++++++++++++ mm/Makefile | 1 + mm/prmem.c (new) | 193 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 271 insertions(+) diff --git a/arch/Kconfig b/arch/Kconfig index b0b6d176f1c1..0380d4a64681 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -814,6 +814,13 @@ config ARCH_HAS_PRMEM architecture specific symbol stating that the architecture provides a back-end function for the write rare operation. +config ARCH_HAS_PRMEM_HEADER + def_bool n + depends on ARCH_HAS_PRMEM + help + architecture specific symbol stating that the architecture provides + own specific header back-end for the write rare operation. + config PRMEM bool "Write protect critical data that doesn't need high write speed." depends on ARCH_HAS_PRMEM diff --git a/include/linux/prmem.h b/include/linux/prmem.h new file mode 100644 index 000000000000..05a5e5b3abfd --- /dev/null +++ b/include/linux/prmem.h @@ -0,0 +1,70 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * prmem.h: Header for memory protection library - generic part + * + * (C) Copyright 2018-2019 Huawei Technologies Co. Ltd. + * Author: Igor Stoppa + */ + +#ifndef _LINUX_PRMEM_H +#define _LINUX_PRMEM_H + +#include +#include +#include + +#ifndef CONFIG_PRMEM + +static inline void *wr_memset(void *p, int c, __kernel_size_t n) +{ + return memset(p, c, n); +} + +static inline void *wr_memcpy(void *p, const void *q, __kernel_size_t n) +{ + return memcpy(p, q, n); +} + +#define wr_assign(var, val) ((var) = (val)) +#define wr_rcu_assign_pointer(p, v) rcu_assign_pointer(p, v) + +#else + +void *wr_memset(void *p, int c, __kernel_size_t n); +void *wr_memcpy(void *p, const void *q, __kernel_size_t n); + +/** + * wr_assign() - sets a write-rare variable to a specified value + * @var: the variable to set + * @val: the new value + * + * Returns: the variable + */ + +#define wr_assign(dst, val) ({ \ + typeof(dst) tmp = (typeof(dst))val; \ + \ + wr_memcpy(&dst, &tmp, sizeof(dst)); \ + dst; \ +}) + +/** + * wr_rcu_assign_pointer() - initialize a pointer in rcu mode + * @p: the rcu pointer - it MUST be aligned to a machine word + * @v: the new value + * + * Returns the value assigned to the rcu pointer. + * + * It is provided as macro, to match rcu_assign_pointer() + * The rcu_assign_pointer() is implemented as equivalent of: + * + * smp_mb(); + * WRITE_ONCE(); + */ +#define wr_rcu_assign_pointer(p, v) ({ \ + smp_mb(); \ + wr_assign(p, v); \ + p; \ +}) +#endif +#endif diff --git a/mm/Makefile b/mm/Makefile index d210cc9d6f80..ef3867c16ce0 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -58,6 +58,7 @@ obj-$(CONFIG_SPARSEMEM) += sparse.o obj-$(CONFIG_SPARSEMEM_VMEMMAP) += sparse-vmemmap.o obj-$(CONFIG_SLOB) += slob.o obj-$(CONFIG_MMU_NOTIFIER) += mmu_notifier.o +obj-$(CONFIG_PRMEM) += prmem.o obj-$(CONFIG_KSM) += ksm.o obj-$(CONFIG_PAGE_POISONING) += page_poison.o obj-$(CONFIG_SLAB) += slab.o diff --git a/mm/prmem.c b/mm/prmem.c new file mode 100644 index 000000000000..455e1e446260 --- /dev/null +++ b/mm/prmem.c @@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * prmem.c: Memory Protection Library + * + * (C) Copyright 2018-2019 Huawei Technologies Co. Ltd. + * Author: Igor Stoppa + */ + +#include +#include + +/* + * In case an architecture needs a different declaration of struct + * wr_state, it can select ARCH_HAS_PRMEM_HEADER and provide its own + * version, accompanied by matching __wr_enable() and __wr_disable() + */ +#ifdef CONFIG_ARCH_HAS_PRMEM_HEADER +#include +#else + +struct wr_state { + struct mm_struct *prev; +}; + +#endif + + +__ro_after_init struct mm_struct *wr_mm; +__ro_after_init unsigned long wr_base; + +/* + * Default implementation of arch-specific functionality. + * Each arch can override the parts that require special handling. + */ +unsigned long __init __weak __init_wr_base(void) +{ + return 0UL; +} + +void * __weak __wr_addr(void *addr) +{ + return (void *)(wr_base + (unsigned long)addr); +} + +void __weak __wr_enable(struct wr_state *state) +{ + lockdep_assert_irqs_disabled(); + state->prev = current->active_mm; + switch_mm_irqs_off(NULL, wr_mm, current); +} + +void __weak __wr_disable(struct wr_state *state) +{ + lockdep_assert_irqs_disabled(); + switch_mm_irqs_off(NULL, state->prev, current); +} + +bool __init __weak __wr_map_address(unsigned long addr) +{ + spinlock_t *ptl; + pte_t pte; + pte_t *ptep; + unsigned long wr_addr; + struct page *page = virt_to_page(addr); + + if (unlikely(!page)) + return false; + wr_addr = (unsigned long)__wr_addr((void *)addr); + + /* The lock is not needed, but avoids open-coding. */ + ptep = get_locked_pte(wr_mm, wr_addr, &ptl); + if (unlikely(!ptep)) + return false; + + pte = mk_pte(page, PAGE_KERNEL); + set_pte_at(wr_mm, wr_addr, ptep, pte); + spin_unlock(ptl); + return true; +} + + +#if ((defined(INLINE_COPY_TO_USER) && !defined(memset_user)) || \ + !defined(INLINE_COPY_TO_USER)) +unsigned long __weak memset_user(void __user *to, int c, unsigned long n) +{ + unsigned long i; + char b = (char)c; + + for (i = 0; i < n; i++) + copy_to_user((void __user *)((unsigned long)to + i), &b, 1); + return n; +} +#endif + +void * __weak __wr_memset(void *p, int c, __kernel_size_t n) +{ + return (void *)memset_user((void __user *)p, (u8)c, n); +} + +void * __weak __wr_memcpy(void *p, const void *q, __kernel_size_t n) +{ + return (void *)copy_to_user((void __user *)p, q, n); +} + +/* + * The following two variables are statically allocated by the linker + * script at the boundaries of the memory region (rounded up to + * multiples of PAGE_SIZE) reserved for __wr_after_init. + */ +extern long __start_wr_after_init; +extern long __end_wr_after_init; +static unsigned long start = (unsigned long)&__start_wr_after_init; +static unsigned long end = (unsigned long)&__end_wr_after_init; +static inline bool is_wr_after_init(void *p, __kernel_size_t n) +{ + unsigned long low = (unsigned long)p; + unsigned long high = low + n; + + return likely(start <= low && high <= end); +} + +#define wr_mem_is_writable() (system_state == SYSTEM_BOOTING) + +/** + * wr_memcpy() - copies n bytes from q to p + * @p: beginning of the memory to write to + * @q: beginning of the memory to read from + * @n: amount of bytes to copy + * + * Returns pointer to the destination + */ +void *wr_memcpy(void *p, const void *q, __kernel_size_t n) +{ + struct wr_state state; + void *wr_addr; + + if (WARN_ONCE(!is_wr_after_init(p, n), "Invalid WR range.")) + return p; + + if (unlikely(wr_mem_is_writable())) + return memcpy(p, q, n); + + wr_addr = __wr_addr(p); + local_irq_disable(); + __wr_enable(&state); + __wr_memcpy(wr_addr, q, n); + __wr_disable(&state); + local_irq_enable(); + return p; +} + +/** + * wr_memset() - sets n bytes of the destination p to the c value + * @p: beginning of the memory to write to + * @c: byte to replicate + * @n: amount of bytes to copy + * + * Returns pointer to the destination + */ +void *wr_memset(void *p, int c, __kernel_size_t n) +{ + struct wr_state state; + void *wr_addr; + + if (WARN_ONCE(!is_wr_after_init(p, n), "Invalid WR range.")) + return p; + + if (unlikely(wr_mem_is_writable())) + return memset(p, c, n); + + wr_addr = __wr_addr(p); + local_irq_disable(); + __wr_enable(&state); + __wr_memset(wr_addr, c, n); + __wr_disable(&state); + local_irq_enable(); + return p; +} + +struct mm_struct *copy_init_mm(void); +void __init wr_init(void) +{ + unsigned long addr; + + wr_mm = copy_init_mm(); + BUG_ON(!wr_mm); + + wr_base = __init_wr_base(); + + /* Create alternate mapping for the entire wr_after_init range. */ + for (addr = start; addr < end; addr += PAGE_SIZE) + BUG_ON(!__wr_map_address(addr)); +} -- 2.19.1