From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756048Ab2FJJXD (ORCPT ); Sun, 10 Jun 2012 05:23:03 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:50509 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755375Ab2FJJXA (ORCPT ); Sun, 10 Jun 2012 05:23:00 -0400 Message-ID: <4FD465EE.8060603@gmail.com> Date: Sun, 10 Jun 2012 11:16:30 +0200 From: Marco Stornelli User-Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0) Gecko/20120421 Thunderbird/12.0 MIME-Version: 1.0 To: Linux Kernel CC: Linux FS Devel Subject: [PATCH 14/17] pramfs: write protection Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marco Stornelli Memory write protection. Signed-off-by: Marco Stornelli --- diff -Nurp linux-3.5-rc2-orig/fs/pramfs/wprotect.c linux-3.5-rc2/fs/pramfs/wprotect.c --- linux-3.5-rc2-orig/fs/pramfs/wprotect.c 1970-01-01 01:00:00.000000000 +0100 +++ linux-3.5-rc2/fs/pramfs/wprotect.c 2012-06-10 10:08:28.000000000 +0200 @@ -0,0 +1,41 @@ +/* + * BRIEF DESCRIPTION + * + * Write protection for the filesystem pages. + * + * Copyright 2009-2011 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" + +DEFINE_SPINLOCK(writeable_lock); + +void pram_writeable(void *vaddr, unsigned long size, int rw) +{ + int ret = 0; + unsigned long nrpages = size >> PAGE_SHIFT; + unsigned long addr = (unsigned long)vaddr; + + /* Page aligned */ + addr &= PAGE_MASK; + + if (size & (PAGE_SIZE - 1)) + nrpages++; + + if (rw) + ret = set_memory_rw(addr, nrpages); + else + ret = set_memory_ro(addr, nrpages); + + BUG_ON(ret); +} diff -Nurp linux-3.5-rc2-orig/fs/pramfs/wprotect.h linux-3.5-rc2/fs/pramfs/wprotect.h --- linux-3.5-rc2-orig/fs/pramfs/wprotect.h 1970-01-01 01:00:00.000000000 +0100 +++ linux-3.5-rc2/fs/pramfs/wprotect.h 2012-06-10 10:08:28.000000000 +0200 @@ -0,0 +1,153 @@ +/* + * BRIEF DESCRIPTION + * + * Memory protection definitions for the PRAMFS filesystem. + * + * Copyright 2010-2011 Marco Stornelli + * 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. + */ + +#ifndef __WPROTECT_H +#define __WPROTECT_H + +#include + +/* pram_memunlock_super() before calling! */ +static inline void pram_sync_super(struct pram_super_block *ps) +{ + u16 crc = 0; + ps->s_wtime = cpu_to_be32(get_seconds()); + ps->s_sum = 0; + crc = crc16(~0, (__u8 *)ps + sizeof(__be16), PRAM_SB_SIZE - + sizeof(__be16)); + ps->s_sum = cpu_to_be16(crc); + /* Keep sync redundant super block */ + memcpy((void *)ps + PRAM_SB_SIZE, (void *)ps, PRAM_SB_SIZE); +} + +/* pram_memunlock_inode() before calling! */ +static inline void pram_sync_inode(struct pram_inode *pi) +{ + u16 crc = 0; + pi->i_sum = 0; + crc = crc16(~0, (__u8 *)pi + sizeof(__be16), PRAM_INODE_SIZE - + sizeof(__be16)); + pi->i_sum = cpu_to_be16(crc); +} + +#ifdef CONFIG_PRAMFS_WRITE_PROTECT +extern void pram_writeable(void *vaddr, unsigned long size, int rw); +extern spinlock_t writeable_lock; +static inline int pram_is_protected(struct super_block *sb) +{ + struct pram_sb_info *sbi = (struct pram_sb_info *)sb->s_fs_info; + return sbi->s_mount_opt & PRAM_MOUNT_PROTECT; +} + +static inline void __pram_memunlock_range(void *p, unsigned long len) +{ + /* + * NOTE: Ideally we should lock all the kernel to be memory safe + * and avoid to write in the protected memory, + * obviously it's not possible, so we only serialize + * the operations at fs level. We can't disable the interrupts + * because we could have a deadlock in this path. + */ + spin_lock(&writeable_lock); + pram_writeable(p, len, 1); +} + +static inline void __pram_memlock_range(void *p, unsigned long len) +{ + pram_writeable(p, len, 0); + spin_unlock(&writeable_lock); +} + +static inline void pram_memunlock_range(struct super_block *sb, void *p, + unsigned long len) +{ + if (pram_is_protected(sb)) + __pram_memunlock_range(p, len); +} + +static inline void pram_memlock_range(struct super_block *sb, void *p, + unsigned long len) +{ + if (pram_is_protected(sb)) + __pram_memlock_range(p, len); +} + +static inline void pram_memunlock_super(struct super_block *sb, + struct pram_super_block *ps) +{ + if (pram_is_protected(sb)) + __pram_memunlock_range(ps, PRAM_SB_SIZE); +} + +static inline void pram_memlock_super(struct super_block *sb, + struct pram_super_block *ps) +{ + pram_sync_super(ps); + if (pram_is_protected(sb)) + __pram_memlock_range(ps, PRAM_SB_SIZE); +} + +static inline void pram_memunlock_inode(struct super_block *sb, + struct pram_inode *pi) +{ + if (pram_is_protected(sb)) + __pram_memunlock_range(pi, PRAM_SB_SIZE); +} + +static inline void pram_memlock_inode(struct super_block *sb, + struct pram_inode *pi) +{ + pram_sync_inode(pi); + if (pram_is_protected(sb)) + __pram_memlock_range(pi, PRAM_SB_SIZE); +} + +static inline void pram_memunlock_block(struct super_block *sb, + void *bp) +{ + if (pram_is_protected(sb)) + __pram_memunlock_range(bp, sb->s_blocksize); +} + +static inline void pram_memlock_block(struct super_block *sb, + void *bp) +{ + if (pram_is_protected(sb)) + __pram_memlock_range(bp, sb->s_blocksize); +} + +#else +#define pram_is_protected(sb) 0 +#define pram_writeable(vaddr, size, rw) do {} while (0) +static inline void pram_memunlock_range(struct super_block *sb, void *p, + unsigned long len) {} +static inline void pram_memlock_range(struct super_block *sb, void *p, + unsigned long len) {} +static inline void pram_memunlock_super(struct super_block *sb, + struct pram_super_block *ps) {} +static inline void pram_memlock_super(struct super_block *sb, + struct pram_super_block *ps) +{ + pram_sync_super(ps); +} +static inline void pram_memunlock_inode(struct super_block *sb, + struct pram_inode *pi) {} +static inline void pram_memlock_inode(struct super_block *sb, + struct pram_inode *pi) +{ + pram_sync_inode(pi); +} +static inline void pram_memunlock_block(struct super_block *sb, + void *bp) {} +static inline void pram_memlock_block(struct super_block *sb, + void *bp) {} + +#endif /* CONFIG PRAMFS_WRITE_PROTECT */ +#endif