From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marco Stornelli Subject: [PATCH 14(16] pramfs: memory protection Date: Sun, 10 Oct 2010 18:36:50 +0200 Message-ID: <4CB1EBA2.8090409@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from :user-agent:mime-version:to:cc:subject:content-type :content-transfer-encoding; bh=2kRM2BA/yMONyqD2y9PibuxEHxKe+VpaK18vETE+SH0=; b=J3xOwzfvQij0K3++67RCs1hMT8SybD6MOiKnHCNmkIJWV/QoSNmyyfx1w+XYa0xwb6 sUhbofBkPkLZ2/+JGmZpAiodMG2ZDUf+i2enITNzgJJ1M2/1GekIwkIYFFY2i4fTCZf0 sJACtW/27Jg2IKDoKiSeYrMo5TThYHLzQvhvw= Sender: linux-embedded-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Linux Kernel Cc: Linux Embedded , Linux FS Devel , Tim Bird , linux-mm@kvack.org From: Marco Stornelli Memory write protection. Signed-off-by: Marco Stornelli --- diff -Nurp linux-2.6.36-orig/fs/pramfs/wprotect.c linux-2.6.36/fs/pramfs/wprotect.c --- linux-2.6.36-orig/fs/pramfs/wprotect.c 1970-01-01 01:00:00.000000000 +0100 +++ linux-2.6.36/fs/pramfs/wprotect.c 2010-09-26 18:04:07.000000000 +0200 @@ -0,0 +1,31 @@ +/* + * FILE NAME fs/pramfs/wprotect.c + * + * BRIEF DESCRIPTION + * + * Write protection for the filesystem pages. + * + * Copyright 2009-2010 Marco Stornelli + * Copyright 2003 Sony Corporation + * Copyright 2003 Matsushita Electric Industrial Co., Ltd. + * 2003-2004 (c) MontaVista Software, Inc. , Steve Longerbeam + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include +#include +#include +#include +#include "pram.h" + +void pram_writeable(void *vaddr, unsigned long size, int rw) +{ + int ret = 0; + + ret = rw ? write_on_kernel_pte_range((unsigned long)vaddr, size) : + write_off_kernel_pte_range((unsigned long)vaddr, size); + + BUG_ON(ret); +} diff -Nurp linux-2.6.36-orig/include/linux/mm.h linux-2.6.36/include/linux/mm.h --- linux-2.6.36-orig/include/linux/mm.h 2010-09-13 01:07:37.000000000 +0200 +++ linux-2.6.36/include/linux/mm.h 2010-09-14 18:49:52.000000000 +0200 @@ -811,6 +811,11 @@ int follow_phys(struct vm_area_struct *v unsigned int flags, unsigned long *prot, resource_size_t *phys); int generic_access_phys(struct vm_area_struct *vma, unsigned long addr, void *buf, int len, int write); +int writeable_kernel_pte_range(unsigned long address, unsigned long size, + unsigned int rw); + +#define write_on_kernel_pte_range(addr, size) writeable_kernel_pte_range(addr, size, 1) +#define write_off_kernel_pte_range(addr, size) writeable_kernel_pte_range(addr, size, 0) static inline void unmap_shared_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen) diff -Nurp linux-2.6.36-orig/mm/memory.c linux-2.6.36/mm/memory.c --- linux-2.6.36-orig/mm/memory.c 2010-09-13 01:07:37.000000000 +0200 +++ linux-2.6.36/mm/memory.c 2010-09-14 18:49:52.000000000 +0200 @@ -3587,3 +3587,49 @@ void might_fault(void) } EXPORT_SYMBOL(might_fault); #endif + +int writeable_kernel_pte_range(unsigned long address, unsigned long size, + unsigned int rw) +{ + + unsigned long addr = address & PAGE_MASK; + unsigned long end = address + size; + unsigned long start = addr; + int ret = -EINVAL; + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *ptep, pte; + + spin_lock_irq(&init_mm.page_table_lock); + + do { + pgd = pgd_offset(&init_mm, address); + if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd))) + goto out; + + pud = pud_offset(pgd, address); + if (pud_none(*pud) || unlikely(pud_bad(*pud))) + goto out; + + pmd = pmd_offset(pud, address); + if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd))) + goto out; + + ptep = pte_offset_kernel(pmd, addr); + pte = *ptep; + if (pte_present(pte)) { + pte = rw ? pte_mkwrite(pte) : pte_wrprotect(pte); + *ptep = pte; + } + addr += PAGE_SIZE; + } while (addr && (addr < end)); + + ret = 0; + +out: + flush_tlb_kernel_range(start, end); + spin_unlock_irq(&init_mm.page_table_lock); + return ret; +} +EXPORT_SYMBOL(writeable_kernel_pte_range);