![Harvey Harrison](/assets/img/avatar_default.png)
__FUNCTION__ is gcc-specific, use __func__ Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Cc: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
530 lines
15 KiB
C
530 lines
15 KiB
C
/**
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* eCryptfs: Linux filesystem encryption layer
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* This is where eCryptfs coordinates the symmetric encryption and
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* decryption of the file data as it passes between the lower
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* encrypted file and the upper decrypted file.
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*
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* Copyright (C) 1997-2003 Erez Zadok
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* Copyright (C) 2001-2003 Stony Brook University
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* Copyright (C) 2004-2007 International Business Machines Corp.
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* Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#include <linux/pagemap.h>
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#include <linux/writeback.h>
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#include <linux/page-flags.h>
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#include <linux/mount.h>
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#include <linux/file.h>
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#include <linux/crypto.h>
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#include <linux/scatterlist.h>
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#include "ecryptfs_kernel.h"
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/**
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* ecryptfs_get_locked_page
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*
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* Get one page from cache or lower f/s, return error otherwise.
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*
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* Returns locked and up-to-date page (if ok), with increased
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* refcnt.
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*/
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struct page *ecryptfs_get_locked_page(struct file *file, loff_t index)
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{
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struct dentry *dentry;
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struct inode *inode;
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struct address_space *mapping;
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struct page *page;
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dentry = file->f_path.dentry;
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inode = dentry->d_inode;
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mapping = inode->i_mapping;
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page = read_mapping_page(mapping, index, (void *)file);
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if (!IS_ERR(page))
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lock_page(page);
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return page;
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}
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/**
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* ecryptfs_writepage
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* @page: Page that is locked before this call is made
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*
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* Returns zero on success; non-zero otherwise
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*/
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static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
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{
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int rc;
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rc = ecryptfs_encrypt_page(page);
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if (rc) {
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ecryptfs_printk(KERN_WARNING, "Error encrypting "
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"page (upper index [0x%.16x])\n", page->index);
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ClearPageUptodate(page);
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goto out;
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}
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SetPageUptodate(page);
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unlock_page(page);
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out:
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return rc;
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}
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/**
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* Header Extent:
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* Octets 0-7: Unencrypted file size (big-endian)
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* Octets 8-15: eCryptfs special marker
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* Octets 16-19: Flags
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* Octet 16: File format version number (between 0 and 255)
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* Octets 17-18: Reserved
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* Octet 19: Bit 1 (lsb): Reserved
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* Bit 2: Encrypted?
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* Bits 3-8: Reserved
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* Octets 20-23: Header extent size (big-endian)
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* Octets 24-25: Number of header extents at front of file
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* (big-endian)
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* Octet 26: Begin RFC 2440 authentication token packet set
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*/
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static void set_header_info(char *page_virt,
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struct ecryptfs_crypt_stat *crypt_stat)
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{
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size_t written;
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size_t save_num_header_bytes_at_front =
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crypt_stat->num_header_bytes_at_front;
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crypt_stat->num_header_bytes_at_front =
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ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
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ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
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crypt_stat->num_header_bytes_at_front =
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save_num_header_bytes_at_front;
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}
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/**
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* ecryptfs_copy_up_encrypted_with_header
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* @page: Sort of a ``virtual'' representation of the encrypted lower
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* file. The actual lower file does not have the metadata in
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* the header. This is locked.
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* @crypt_stat: The eCryptfs inode's cryptographic context
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*
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* The ``view'' is the version of the file that userspace winds up
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* seeing, with the header information inserted.
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*/
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static int
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ecryptfs_copy_up_encrypted_with_header(struct page *page,
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struct ecryptfs_crypt_stat *crypt_stat)
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{
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loff_t extent_num_in_page = 0;
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loff_t num_extents_per_page = (PAGE_CACHE_SIZE
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/ crypt_stat->extent_size);
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int rc = 0;
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while (extent_num_in_page < num_extents_per_page) {
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loff_t view_extent_num = ((((loff_t)page->index)
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* num_extents_per_page)
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+ extent_num_in_page);
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size_t num_header_extents_at_front =
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(crypt_stat->num_header_bytes_at_front
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/ crypt_stat->extent_size);
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if (view_extent_num < num_header_extents_at_front) {
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/* This is a header extent */
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char *page_virt;
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page_virt = kmap_atomic(page, KM_USER0);
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memset(page_virt, 0, PAGE_CACHE_SIZE);
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/* TODO: Support more than one header extent */
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if (view_extent_num == 0) {
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rc = ecryptfs_read_xattr_region(
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page_virt, page->mapping->host);
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set_header_info(page_virt, crypt_stat);
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}
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kunmap_atomic(page_virt, KM_USER0);
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flush_dcache_page(page);
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if (rc) {
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printk(KERN_ERR "%s: Error reading xattr "
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"region; rc = [%d]\n", __func__, rc);
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goto out;
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}
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} else {
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/* This is an encrypted data extent */
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loff_t lower_offset =
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((view_extent_num * crypt_stat->extent_size)
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- crypt_stat->num_header_bytes_at_front);
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rc = ecryptfs_read_lower_page_segment(
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page, (lower_offset >> PAGE_CACHE_SHIFT),
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(lower_offset & ~PAGE_CACHE_MASK),
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crypt_stat->extent_size, page->mapping->host);
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if (rc) {
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printk(KERN_ERR "%s: Error attempting to read "
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"extent at offset [%lld] in the lower "
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"file; rc = [%d]\n", __func__,
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lower_offset, rc);
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goto out;
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}
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}
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extent_num_in_page++;
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}
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out:
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return rc;
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}
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/**
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* ecryptfs_readpage
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* @file: An eCryptfs file
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* @page: Page from eCryptfs inode mapping into which to stick the read data
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*
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* Read in a page, decrypting if necessary.
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*
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* Returns zero on success; non-zero on error.
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*/
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static int ecryptfs_readpage(struct file *file, struct page *page)
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{
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struct ecryptfs_crypt_stat *crypt_stat =
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&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
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int rc = 0;
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if (!crypt_stat
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|| !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
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|| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
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ecryptfs_printk(KERN_DEBUG,
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"Passing through unencrypted page\n");
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rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
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PAGE_CACHE_SIZE,
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page->mapping->host);
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} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
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if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
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rc = ecryptfs_copy_up_encrypted_with_header(page,
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crypt_stat);
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if (rc) {
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printk(KERN_ERR "%s: Error attempting to copy "
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"the encrypted content from the lower "
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"file whilst inserting the metadata "
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"from the xattr into the header; rc = "
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"[%d]\n", __func__, rc);
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goto out;
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}
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} else {
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rc = ecryptfs_read_lower_page_segment(
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page, page->index, 0, PAGE_CACHE_SIZE,
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page->mapping->host);
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if (rc) {
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printk(KERN_ERR "Error reading page; rc = "
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"[%d]\n", rc);
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goto out;
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}
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}
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} else {
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rc = ecryptfs_decrypt_page(page);
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if (rc) {
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ecryptfs_printk(KERN_ERR, "Error decrypting page; "
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"rc = [%d]\n", rc);
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goto out;
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}
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}
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out:
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if (rc)
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ClearPageUptodate(page);
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else
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SetPageUptodate(page);
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ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
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page->index);
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unlock_page(page);
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return rc;
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}
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/**
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* Called with lower inode mutex held.
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*/
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static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
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{
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struct inode *inode = page->mapping->host;
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int end_byte_in_page;
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if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
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goto out;
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end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
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if (to > end_byte_in_page)
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end_byte_in_page = to;
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zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
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out:
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return 0;
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}
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/**
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* ecryptfs_prepare_write
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* @file: The eCryptfs file
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* @page: The eCryptfs page
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* @from: The start byte from which we will write
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* @to: The end byte to which we will write
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*
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* This function must zero any hole we create
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*
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* Returns zero on success; non-zero otherwise
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*/
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static int ecryptfs_prepare_write(struct file *file, struct page *page,
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unsigned from, unsigned to)
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{
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loff_t prev_page_end_size;
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int rc = 0;
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if (!PageUptodate(page)) {
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struct ecryptfs_crypt_stat *crypt_stat =
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&ecryptfs_inode_to_private(
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file->f_path.dentry->d_inode)->crypt_stat;
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if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
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|| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
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rc = ecryptfs_read_lower_page_segment(
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page, page->index, 0, PAGE_CACHE_SIZE,
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page->mapping->host);
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if (rc) {
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printk(KERN_ERR "%s: Error attemping to read "
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"lower page segment; rc = [%d]\n",
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__func__, rc);
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ClearPageUptodate(page);
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goto out;
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} else
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SetPageUptodate(page);
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} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
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if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
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rc = ecryptfs_copy_up_encrypted_with_header(
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page, crypt_stat);
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if (rc) {
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printk(KERN_ERR "%s: Error attempting "
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"to copy the encrypted content "
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"from the lower file whilst "
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"inserting the metadata from "
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"the xattr into the header; rc "
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"= [%d]\n", __func__, rc);
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ClearPageUptodate(page);
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goto out;
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}
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SetPageUptodate(page);
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} else {
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rc = ecryptfs_read_lower_page_segment(
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page, page->index, 0, PAGE_CACHE_SIZE,
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page->mapping->host);
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if (rc) {
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printk(KERN_ERR "%s: Error reading "
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"page; rc = [%d]\n",
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__func__, rc);
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ClearPageUptodate(page);
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goto out;
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}
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SetPageUptodate(page);
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}
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} else {
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rc = ecryptfs_decrypt_page(page);
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if (rc) {
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printk(KERN_ERR "%s: Error decrypting page "
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"at index [%ld]; rc = [%d]\n",
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__func__, page->index, rc);
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ClearPageUptodate(page);
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goto out;
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}
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SetPageUptodate(page);
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}
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}
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prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);
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/* If creating a page or more of holes, zero them out via truncate.
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* Note, this will increase i_size. */
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if (page->index != 0) {
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if (prev_page_end_size > i_size_read(page->mapping->host)) {
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rc = ecryptfs_truncate(file->f_path.dentry,
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prev_page_end_size);
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if (rc) {
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printk(KERN_ERR "%s: Error on attempt to "
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"truncate to (higher) offset [%lld];"
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" rc = [%d]\n", __func__,
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prev_page_end_size, rc);
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goto out;
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}
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}
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}
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/* Writing to a new page, and creating a small hole from start
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* of page? Zero it out. */
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if ((i_size_read(page->mapping->host) == prev_page_end_size)
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&& (from != 0))
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zero_user(page, 0, PAGE_CACHE_SIZE);
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out:
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return rc;
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}
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/**
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* ecryptfs_write_inode_size_to_header
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*
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* Writes the lower file size to the first 8 bytes of the header.
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*
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* Returns zero on success; non-zero on error.
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*/
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static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
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{
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u64 file_size;
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char *file_size_virt;
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int rc;
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file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
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if (!file_size_virt) {
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rc = -ENOMEM;
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goto out;
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}
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file_size = (u64)i_size_read(ecryptfs_inode);
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file_size = cpu_to_be64(file_size);
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memcpy(file_size_virt, &file_size, sizeof(u64));
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rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
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sizeof(u64));
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kfree(file_size_virt);
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if (rc)
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printk(KERN_ERR "%s: Error writing file size to header; "
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"rc = [%d]\n", __func__, rc);
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out:
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return rc;
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}
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struct kmem_cache *ecryptfs_xattr_cache;
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static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
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{
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ssize_t size;
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void *xattr_virt;
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struct dentry *lower_dentry =
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ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
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struct inode *lower_inode = lower_dentry->d_inode;
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u64 file_size;
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int rc;
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if (!lower_inode->i_op->getxattr || !lower_inode->i_op->setxattr) {
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printk(KERN_WARNING
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"No support for setting xattr in lower filesystem\n");
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rc = -ENOSYS;
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goto out;
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}
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xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
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if (!xattr_virt) {
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printk(KERN_ERR "Out of memory whilst attempting to write "
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"inode size to xattr\n");
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rc = -ENOMEM;
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goto out;
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}
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mutex_lock(&lower_inode->i_mutex);
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size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
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xattr_virt, PAGE_CACHE_SIZE);
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if (size < 0)
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size = 8;
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file_size = (u64)i_size_read(ecryptfs_inode);
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file_size = cpu_to_be64(file_size);
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memcpy(xattr_virt, &file_size, sizeof(u64));
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rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
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xattr_virt, size, 0);
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mutex_unlock(&lower_inode->i_mutex);
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if (rc)
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printk(KERN_ERR "Error whilst attempting to write inode size "
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"to lower file xattr; rc = [%d]\n", rc);
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kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
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out:
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return rc;
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}
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int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
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{
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struct ecryptfs_crypt_stat *crypt_stat;
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crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
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if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
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return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
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else
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return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
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}
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/**
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* ecryptfs_commit_write
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* @file: The eCryptfs file object
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* @page: The eCryptfs page
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* @from: Ignored (we rotate the page IV on each write)
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* @to: Ignored
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*
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* This is where we encrypt the data and pass the encrypted data to
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* the lower filesystem. In OpenPGP-compatible mode, we operate on
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* entire underlying packets.
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*/
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static int ecryptfs_commit_write(struct file *file, struct page *page,
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unsigned from, unsigned to)
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{
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loff_t pos;
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struct inode *ecryptfs_inode = page->mapping->host;
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struct ecryptfs_crypt_stat *crypt_stat =
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&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
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int rc;
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if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
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ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
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"crypt_stat at memory location [%p]\n", crypt_stat);
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crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
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} else
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ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
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ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
|
|
"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
|
|
to);
|
|
/* Fills in zeros if 'to' goes beyond inode size */
|
|
rc = fill_zeros_to_end_of_page(page, to);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
|
|
"zeros in page with index = [0x%.16x]\n",
|
|
page->index);
|
|
goto out;
|
|
}
|
|
rc = ecryptfs_encrypt_page(page);
|
|
if (rc) {
|
|
ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
|
|
"index [0x%.16x])\n", page->index);
|
|
goto out;
|
|
}
|
|
pos = (((loff_t)page->index) << PAGE_CACHE_SHIFT) + to;
|
|
if (pos > i_size_read(ecryptfs_inode)) {
|
|
i_size_write(ecryptfs_inode, pos);
|
|
ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
|
|
"[0x%.16x]\n", i_size_read(ecryptfs_inode));
|
|
}
|
|
rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
|
|
if (rc)
|
|
printk(KERN_ERR "Error writing inode size to metadata; "
|
|
"rc = [%d]\n", rc);
|
|
out:
|
|
return rc;
|
|
}
|
|
|
|
static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
|
|
{
|
|
int rc = 0;
|
|
struct inode *inode;
|
|
struct inode *lower_inode;
|
|
|
|
inode = (struct inode *)mapping->host;
|
|
lower_inode = ecryptfs_inode_to_lower(inode);
|
|
if (lower_inode->i_mapping->a_ops->bmap)
|
|
rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
|
|
block);
|
|
return rc;
|
|
}
|
|
|
|
struct address_space_operations ecryptfs_aops = {
|
|
.writepage = ecryptfs_writepage,
|
|
.readpage = ecryptfs_readpage,
|
|
.prepare_write = ecryptfs_prepare_write,
|
|
.commit_write = ecryptfs_commit_write,
|
|
.bmap = ecryptfs_bmap,
|
|
};
|