![Michael Halcrow](/assets/img/avatar_default.png)
The functions that eventually call down to ecryptfs_read_lower(), ecryptfs_decrypt_page(), and ecryptfs_copy_up_encrypted_with_header() should have the responsibility of managing the page Uptodate status. This patch gets rid of some of the ugliness that resulted from trying to push some of the page flag setting too far down the stack. Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
358 lines
11 KiB
C
358 lines
11 KiB
C
/**
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* eCryptfs: Linux filesystem encryption layer
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*
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* Copyright (C) 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/fs.h>
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#include <linux/pagemap.h>
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#include "ecryptfs_kernel.h"
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/**
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* ecryptfs_write_lower
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* @ecryptfs_inode: The eCryptfs inode
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* @data: Data to write
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* @offset: Byte offset in the lower file to which to write the data
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* @size: Number of bytes from @data to write at @offset in the lower
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* file
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*
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* Write data to the lower file.
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*
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* Returns zero on success; non-zero on error
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*/
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int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data,
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loff_t offset, size_t size)
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{
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struct ecryptfs_inode_info *inode_info;
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ssize_t octets_written;
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mm_segment_t fs_save;
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int rc = 0;
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inode_info = ecryptfs_inode_to_private(ecryptfs_inode);
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mutex_lock(&inode_info->lower_file_mutex);
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BUG_ON(!inode_info->lower_file);
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inode_info->lower_file->f_pos = offset;
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fs_save = get_fs();
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set_fs(get_ds());
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octets_written = vfs_write(inode_info->lower_file, data, size,
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&inode_info->lower_file->f_pos);
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set_fs(fs_save);
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if (octets_written < 0) {
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printk(KERN_ERR "%s: octets_written = [%td]; "
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"expected [%td]\n", __FUNCTION__, octets_written, size);
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rc = -EINVAL;
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}
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mutex_unlock(&inode_info->lower_file_mutex);
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mark_inode_dirty_sync(ecryptfs_inode);
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return rc;
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}
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/**
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* ecryptfs_write_lower_page_segment
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* @ecryptfs_inode: The eCryptfs inode
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* @page_for_lower: The page containing the data to be written to the
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* lower file
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* @offset_in_page: The offset in the @page_for_lower from which to
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* start writing the data
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* @size: The amount of data from @page_for_lower to write to the
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* lower file
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*
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* Determines the byte offset in the file for the given page and
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* offset within the page, maps the page, and makes the call to write
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* the contents of @page_for_lower to the lower inode.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
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struct page *page_for_lower,
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size_t offset_in_page, size_t size)
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{
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char *virt;
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loff_t offset;
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int rc;
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offset = ((((off_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
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+ offset_in_page);
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virt = kmap(page_for_lower);
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rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
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kunmap(page_for_lower);
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return rc;
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}
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/**
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* ecryptfs_write
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* @ecryptfs_file: The eCryptfs file into which to write
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* @data: Virtual address where data to write is located
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* @offset: Offset in the eCryptfs file at which to begin writing the
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* data from @data
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* @size: The number of bytes to write from @data
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*
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* Write an arbitrary amount of data to an arbitrary location in the
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* eCryptfs inode page cache. This is done on a page-by-page, and then
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* by an extent-by-extent, basis; individual extents are encrypted and
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* written to the lower page cache (via VFS writes). This function
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* takes care of all the address translation to locations in the lower
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* filesystem; it also handles truncate events, writing out zeros
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* where necessary.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset,
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size_t size)
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{
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struct page *ecryptfs_page;
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char *ecryptfs_page_virt;
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loff_t ecryptfs_file_size =
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i_size_read(ecryptfs_file->f_dentry->d_inode);
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loff_t data_offset = 0;
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loff_t pos;
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int rc = 0;
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if (offset > ecryptfs_file_size)
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pos = ecryptfs_file_size;
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else
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pos = offset;
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while (pos < (offset + size)) {
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pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
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size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
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size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
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size_t total_remaining_bytes = ((offset + size) - pos);
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if (num_bytes > total_remaining_bytes)
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num_bytes = total_remaining_bytes;
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if (pos < offset) {
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size_t total_remaining_zeros = (offset - pos);
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if (num_bytes > total_remaining_zeros)
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num_bytes = total_remaining_zeros;
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}
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ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file,
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ecryptfs_page_idx);
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if (IS_ERR(ecryptfs_page)) {
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rc = PTR_ERR(ecryptfs_page);
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printk(KERN_ERR "%s: Error getting page at "
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"index [%ld] from eCryptfs inode "
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"mapping; rc = [%d]\n", __FUNCTION__,
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ecryptfs_page_idx, rc);
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goto out;
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}
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if (start_offset_in_page) {
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/* Read in the page from the lower
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* into the eCryptfs inode page cache,
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* decrypting */
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rc = ecryptfs_decrypt_page(ecryptfs_page);
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if (rc) {
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printk(KERN_ERR "%s: Error decrypting "
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"page; rc = [%d]\n",
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__FUNCTION__, rc);
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ClearPageUptodate(ecryptfs_page);
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page_cache_release(ecryptfs_page);
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goto out;
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}
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}
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ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
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if (pos >= offset) {
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memcpy(((char *)ecryptfs_page_virt
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+ start_offset_in_page),
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(data + data_offset), num_bytes);
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data_offset += num_bytes;
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} else {
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/* We are extending past the previous end of the file.
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* Fill in zero values up to the start of where we
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* will be writing data. */
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memset(((char *)ecryptfs_page_virt
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+ start_offset_in_page), 0, num_bytes);
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}
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kunmap_atomic(ecryptfs_page_virt, KM_USER0);
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flush_dcache_page(ecryptfs_page);
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SetPageUptodate(ecryptfs_page);
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unlock_page(ecryptfs_page);
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rc = ecryptfs_encrypt_page(ecryptfs_page);
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page_cache_release(ecryptfs_page);
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if (rc) {
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printk(KERN_ERR "%s: Error encrypting "
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"page; rc = [%d]\n", __FUNCTION__, rc);
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goto out;
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}
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pos += num_bytes;
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}
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if ((offset + size) > ecryptfs_file_size) {
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i_size_write(ecryptfs_file->f_dentry->d_inode, (offset + size));
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rc = ecryptfs_write_inode_size_to_metadata(
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ecryptfs_file->f_dentry->d_inode);
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if (rc) {
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printk(KERN_ERR "Problem with "
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"ecryptfs_write_inode_size_to_metadata; "
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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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return rc;
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}
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/**
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* ecryptfs_read_lower
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* @data: The read data is stored here by this function
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* @offset: Byte offset in the lower file from which to read the data
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* @size: Number of bytes to read from @offset of the lower file and
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* store into @data
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* @ecryptfs_inode: The eCryptfs inode
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*
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* Read @size bytes of data at byte offset @offset from the lower
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* inode into memory location @data.
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*
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* Returns zero on success; non-zero on error
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*/
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int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
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struct inode *ecryptfs_inode)
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{
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struct ecryptfs_inode_info *inode_info =
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ecryptfs_inode_to_private(ecryptfs_inode);
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ssize_t octets_read;
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mm_segment_t fs_save;
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int rc = 0;
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mutex_lock(&inode_info->lower_file_mutex);
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BUG_ON(!inode_info->lower_file);
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inode_info->lower_file->f_pos = offset;
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fs_save = get_fs();
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set_fs(get_ds());
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octets_read = vfs_read(inode_info->lower_file, data, size,
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&inode_info->lower_file->f_pos);
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set_fs(fs_save);
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if (octets_read < 0) {
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printk(KERN_ERR "%s: octets_read = [%td]; "
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"expected [%td]\n", __FUNCTION__, octets_read, size);
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rc = -EINVAL;
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}
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mutex_unlock(&inode_info->lower_file_mutex);
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return rc;
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}
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/**
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* ecryptfs_read_lower_page_segment
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* @page_for_ecryptfs: The page into which data for eCryptfs will be
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* written
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* @offset_in_page: Offset in @page_for_ecryptfs from which to start
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* writing
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* @size: The number of bytes to write into @page_for_ecryptfs
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* @ecryptfs_inode: The eCryptfs inode
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*
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* Determines the byte offset in the file for the given page and
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* offset within the page, maps the page, and makes the call to read
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* the contents of @page_for_ecryptfs from the lower inode.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
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pgoff_t page_index,
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size_t offset_in_page, size_t size,
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struct inode *ecryptfs_inode)
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{
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char *virt;
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loff_t offset;
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int rc;
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offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page);
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virt = kmap(page_for_ecryptfs);
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rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
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kunmap(page_for_ecryptfs);
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flush_dcache_page(page_for_ecryptfs);
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return rc;
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}
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/**
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* ecryptfs_read
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* @data: The virtual address into which to write the data read (and
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* possibly decrypted) from the lower file
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* @offset: The offset in the decrypted view of the file from which to
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* read into @data
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* @size: The number of bytes to read into @data
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* @ecryptfs_file: The eCryptfs file from which to read
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*
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* Read an arbitrary amount of data from an arbitrary location in the
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* eCryptfs page cache. This is done on an extent-by-extent basis;
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* individual extents are decrypted and read from the lower page
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* cache (via VFS reads). This function takes care of all the
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* address translation to locations in the lower filesystem.
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*
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* Returns zero on success; non-zero otherwise
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*/
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int ecryptfs_read(char *data, loff_t offset, size_t size,
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struct file *ecryptfs_file)
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{
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struct page *ecryptfs_page;
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char *ecryptfs_page_virt;
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loff_t ecryptfs_file_size =
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i_size_read(ecryptfs_file->f_dentry->d_inode);
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loff_t data_offset = 0;
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loff_t pos;
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int rc = 0;
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if ((offset + size) > ecryptfs_file_size) {
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rc = -EINVAL;
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printk(KERN_ERR "%s: Attempt to read data past the end of the "
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"file; offset = [%lld]; size = [%td]; "
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"ecryptfs_file_size = [%lld]\n",
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__FUNCTION__, offset, size, ecryptfs_file_size);
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goto out;
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}
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pos = offset;
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while (pos < (offset + size)) {
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pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
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size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
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size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
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size_t total_remaining_bytes = ((offset + size) - pos);
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if (num_bytes > total_remaining_bytes)
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num_bytes = total_remaining_bytes;
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ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file,
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ecryptfs_page_idx);
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if (IS_ERR(ecryptfs_page)) {
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rc = PTR_ERR(ecryptfs_page);
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printk(KERN_ERR "%s: Error getting page at "
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"index [%ld] from eCryptfs inode "
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"mapping; rc = [%d]\n", __FUNCTION__,
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ecryptfs_page_idx, rc);
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goto out;
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}
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rc = ecryptfs_decrypt_page(ecryptfs_page);
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if (rc) {
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printk(KERN_ERR "%s: Error decrypting "
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"page; rc = [%d]\n", __FUNCTION__, rc);
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ClearPageUptodate(ecryptfs_page);
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page_cache_release(ecryptfs_page);
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goto out;
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}
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ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
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memcpy((data + data_offset),
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((char *)ecryptfs_page_virt + start_offset_in_page),
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num_bytes);
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kunmap_atomic(ecryptfs_page_virt, KM_USER0);
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flush_dcache_page(ecryptfs_page);
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SetPageUptodate(ecryptfs_page);
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unlock_page(ecryptfs_page);
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page_cache_release(ecryptfs_page);
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pos += num_bytes;
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data_offset += num_bytes;
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}
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out:
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return rc;
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}
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