[deliverable/linux.git] / fs / ecryptfs / mmap.c

/**
 * eCryptfs: Linux filesystem encryption layer
 * This is where eCryptfs coordinates the symmetric encryption and
 * decryption of the file data as it passes between the lower
 * encrypted file and the upper decrypted file.
 *
 * Copyright (C) 1997-2003 Erez Zadok
 * Copyright (C) 2001-2003 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/page-flags.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include "ecryptfs_kernel.h"

struct kmem_cache *ecryptfs_lower_page_cache;

/**
 * ecryptfs_get_locked_page
 *
 * Get one page from cache or lower f/s, return error otherwise.
 *
 * Returns locked and up-to-date page (if ok), with increased
 * refcnt.
 */
struct page *ecryptfs_get_locked_page(struct file *file, loff_t index)
{
	struct dentry *dentry;
	struct inode *inode;
	struct address_space *mapping;
	struct page *page;

	dentry = file->f_path.dentry;
	inode = dentry->d_inode;
	mapping = inode->i_mapping;
	page = read_mapping_page(mapping, index, (void *)file);
	if (!IS_ERR(page))
		lock_page(page);
	return page;
}

/**
 * ecryptfs_writepage
 * @page: Page that is locked before this call is made
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
{
	int rc;

	rc = ecryptfs_encrypt_page(page);
	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error encrypting "
				"page (upper index [0x%.16x])\n", page->index);
		ClearPageUptodate(page);
		goto out;
	}
	SetPageUptodate(page);
	unlock_page(page);
out:
	return rc;
}

/**
 *   Header Extent:
 *     Octets 0-7:        Unencrypted file size (big-endian)
 *     Octets 8-15:       eCryptfs special marker
 *     Octets 16-19:      Flags
 *      Octet 16:         File format version number (between 0 and 255)
 *      Octets 17-18:     Reserved
 *      Octet 19:         Bit 1 (lsb): Reserved
 *                        Bit 2: Encrypted?
 *                        Bits 3-8: Reserved
 *     Octets 20-23:      Header extent size (big-endian)
 *     Octets 24-25:      Number of header extents at front of file
 *                        (big-endian)
 *     Octet  26:         Begin RFC 2440 authentication token packet set
 */
static void set_header_info(char *page_virt,
			    struct ecryptfs_crypt_stat *crypt_stat)
{
	size_t written;
	int save_num_header_extents_at_front =
		crypt_stat->num_header_extents_at_front;

	crypt_stat->num_header_extents_at_front = 1;
	ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
	crypt_stat->num_header_extents_at_front =
		save_num_header_extents_at_front;
}

/**
 * ecryptfs_copy_up_encrypted_with_header
 * @page: Sort of a ``virtual'' representation of the encrypted lower
 *        file. The actual lower file does not have the metadata in
 *        the header. This is locked.
 * @crypt_stat: The eCryptfs inode's cryptographic context
 *
 * The ``view'' is the version of the file that userspace winds up
 * seeing, with the header information inserted.
 */
static int
ecryptfs_copy_up_encrypted_with_header(struct page *page,
				       struct ecryptfs_crypt_stat *crypt_stat)
{
	loff_t extent_num_in_page = 0;
	loff_t num_extents_per_page = (PAGE_CACHE_SIZE
				       / crypt_stat->extent_size);
	int rc = 0;

	while (extent_num_in_page < num_extents_per_page) {
		loff_t view_extent_num = ((((loff_t)page->index)
					   * num_extents_per_page)
					  + extent_num_in_page);

		if (view_extent_num < crypt_stat->num_header_extents_at_front) {
			/* This is a header extent */
			char *page_virt;

			page_virt = kmap_atomic(page, KM_USER0);
			memset(page_virt, 0, PAGE_CACHE_SIZE);
			/* TODO: Support more than one header extent */
			if (view_extent_num == 0) {
				rc = ecryptfs_read_xattr_region(
					page_virt, page->mapping->host);
				set_header_info(page_virt, crypt_stat);
			}
			kunmap_atomic(page_virt, KM_USER0);
			flush_dcache_page(page);
			if (rc) {
				printk(KERN_ERR "%s: Error reading xattr "
				       "region; rc = [%d]\n", __FUNCTION__, rc);
				goto out;
			}
		} else {
			/* This is an encrypted data extent */
			loff_t lower_offset =
				((view_extent_num -
				  crypt_stat->num_header_extents_at_front)
				 * crypt_stat->extent_size);

			rc = ecryptfs_read_lower_page_segment(
				page, (lower_offset >> PAGE_CACHE_SHIFT),
				(lower_offset & ~PAGE_CACHE_MASK),
				crypt_stat->extent_size, page->mapping->host);
			if (rc) {
				printk(KERN_ERR "%s: Error attempting to read "
				       "extent at offset [%lld] in the lower "
				       "file; rc = [%d]\n", __FUNCTION__,
				       lower_offset, rc);
				goto out;
			}
		}
		extent_num_in_page++;
	}
out:
	return rc;
}

/**
 * ecryptfs_readpage
 * @file: An eCryptfs file
 * @page: Page from eCryptfs inode mapping into which to stick the read data
 *
 * Read in a page, decrypting if necessary.
 *
 * Returns zero on success; non-zero on error.
 */
static int ecryptfs_readpage(struct file *file, struct page *page)
{
	struct ecryptfs_crypt_stat *crypt_stat =
		&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
	int rc = 0;

	if (!crypt_stat
	    || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
	    || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
		ecryptfs_printk(KERN_DEBUG,
				"Passing through unencrypted page\n");
		rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
						      PAGE_CACHE_SIZE,
						      page->mapping->host);
	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
		if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
			rc = ecryptfs_copy_up_encrypted_with_header(page,
								    crypt_stat);
			if (rc) {
				printk(KERN_ERR "%s: Error attempting to copy "
				       "the encrypted content from the lower "
				       "file whilst inserting the metadata "
				       "from the xattr into the header; rc = "
				       "[%d]\n", __FUNCTION__, rc);
				goto out;
			}

		} else {
			rc = ecryptfs_read_lower_page_segment(
				page, page->index, 0, PAGE_CACHE_SIZE,
				page->mapping->host);
			if (rc) {
				printk(KERN_ERR "Error reading page; rc = "
				       "[%d]\n", rc);
				goto out;
			}
		}
	} else {
		rc = ecryptfs_decrypt_page(page);
		if (rc) {
			ecryptfs_printk(KERN_ERR, "Error decrypting page; "
					"rc = [%d]\n", rc);
			goto out;
		}
	}
out:
	if (rc)
		ClearPageUptodate(page);
	else
		SetPageUptodate(page);
	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
			page->index);
	unlock_page(page);
	return rc;
}

/**
 * Called with lower inode mutex held.
 */
static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
{
	struct inode *inode = page->mapping->host;
	int end_byte_in_page;

	if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
		goto out;
	end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
	if (to > end_byte_in_page)
		end_byte_in_page = to;
	zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
out:
	return 0;
}

/* This function must zero any hole we create */
static int ecryptfs_prepare_write(struct file *file, struct page *page,
				  unsigned from, unsigned to)
{
	int rc = 0;
	loff_t prev_page_end_size;

	if (!PageUptodate(page)) {
		rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
						      PAGE_CACHE_SIZE,
						      page->mapping->host);
		if (rc) {
			printk(KERN_ERR "%s: Error attemping to read lower "
			       "page segment; rc = [%d]\n", __FUNCTION__, rc);
			ClearPageUptodate(page);
			goto out;
		} else
			SetPageUptodate(page);
	}

	prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);

	/*
	 * If creating a page or more of holes, zero them out via truncate.
	 * Note, this will increase i_size.
	 */
	if (page->index != 0) {
		if (prev_page_end_size > i_size_read(page->mapping->host)) {
			rc = ecryptfs_truncate(file->f_path.dentry,
					       prev_page_end_size);
			if (rc) {
				printk(KERN_ERR "Error on attempt to "
				       "truncate to (higher) offset [%lld];"
				       " rc = [%d]\n", prev_page_end_size, rc);
				goto out;
			}
		}
	}
	/*
	 * Writing to a new page, and creating a small hole from start of page?
	 * Zero it out.
	 */
	if ((i_size_read(page->mapping->host) == prev_page_end_size) &&
	    (from != 0)) {
		zero_user(page, 0, PAGE_CACHE_SIZE);
	}
out:
	return rc;
}

/**
 * ecryptfs_write_inode_size_to_header
 *
 * Writes the lower file size to the first 8 bytes of the header.
 *
 * Returns zero on success; non-zero on error.
 */
static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
{
	u64 file_size;
	char *file_size_virt;
	int rc;

	file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
	if (!file_size_virt) {
		rc = -ENOMEM;
		goto out;
	}
	file_size = (u64)i_size_read(ecryptfs_inode);
	file_size = cpu_to_be64(file_size);
	memcpy(file_size_virt, &file_size, sizeof(u64));
	rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
				  sizeof(u64));
	kfree(file_size_virt);
	if (rc)
		printk(KERN_ERR "%s: Error writing file size to header; "
		       "rc = [%d]\n", __FUNCTION__, rc);
out:
	return rc;
}

struct kmem_cache *ecryptfs_xattr_cache;

static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
{
	ssize_t size;
	void *xattr_virt;
	struct dentry *lower_dentry =
		ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
	struct inode *lower_inode = lower_dentry->d_inode;
	u64 file_size;
	int rc;

	if (!lower_inode->i_op->getxattr || !lower_inode->i_op->setxattr) {
		printk(KERN_WARNING
		       "No support for setting xattr in lower filesystem\n");
		rc = -ENOSYS;
		goto out;
	}
	xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
	if (!xattr_virt) {
		printk(KERN_ERR "Out of memory whilst attempting to write "
		       "inode size to xattr\n");
		rc = -ENOMEM;
		goto out;
	}
	mutex_lock(&lower_inode->i_mutex);
	size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
					   xattr_virt, PAGE_CACHE_SIZE);
	if (size < 0)
		size = 8;
	file_size = (u64)i_size_read(ecryptfs_inode);
	file_size = cpu_to_be64(file_size);
	memcpy(xattr_virt, &file_size, sizeof(u64));
	rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
					 xattr_virt, size, 0);
	mutex_unlock(&lower_inode->i_mutex);
	if (rc)
		printk(KERN_ERR "Error whilst attempting to write inode size "
		       "to lower file xattr; rc = [%d]\n", rc);
	kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
out:
	return rc;
}

int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
{
	struct ecryptfs_crypt_stat *crypt_stat;

	crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
		return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
	else
		return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
}

/**
 * ecryptfs_commit_write
 * @file: The eCryptfs file object
 * @page: The eCryptfs page
 * @from: Ignored (we rotate the page IV on each write)
 * @to: Ignored
 *
 * This is where we encrypt the data and pass the encrypted data to
 * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 * entire underlying packets.
 */
static int ecryptfs_commit_write(struct file *file, struct page *page,
				 unsigned from, unsigned to)
{
	loff_t pos;
	struct inode *ecryptfs_inode = page->mapping->host;
	struct ecryptfs_crypt_stat *crypt_stat =
		&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
	int rc;

	if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
		ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
			"crypt_stat at memory location [%p]\n", crypt_stat);
		crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
	} else
		ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
	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,
};
Commit	Line	Data
237fead6 MH	1	/**
	2	* eCryptfs: Linux filesystem encryption layer
	3	* This is where eCryptfs coordinates the symmetric encryption and
	4	* decryption of the file data as it passes between the lower
	5	* encrypted file and the upper decrypted file.
	6	*
	7	* Copyright (C) 1997-2003 Erez Zadok
	8	* Copyright (C) 2001-2003 Stony Brook University
dd2a3b7a	9	* Copyright (C) 2004-2007 International Business Machines Corp.
237fead6 MH	10	* Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
	11	*
	12	* This program is free software; you can redistribute it and/or
	13	* modify it under the terms of the GNU General Public License as
	14	* published by the Free Software Foundation; either version 2 of the
	15	* License, or (at your option) any later version.
	16	*
	17	* This program is distributed in the hope that it will be useful, but
	18	* WITHOUT ANY WARRANTY; without even the implied warranty of
	19	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	20	* General Public License for more details.
	21	*
	22	* You should have received a copy of the GNU General Public License
	23	* along with this program; if not, write to the Free Software
	24	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	25	* 02111-1307, USA.
	26	*/
	27
	28	#include <linux/pagemap.h>
	29	#include <linux/writeback.h>
	30	#include <linux/page-flags.h>
	31	#include <linux/mount.h>
	32	#include <linux/file.h>
	33	#include <linux/crypto.h>
	34	#include <linux/scatterlist.h>
	35	#include "ecryptfs_kernel.h"
	36
	37	struct kmem_cache *ecryptfs_lower_page_cache;
	38
	39	/**
16a72c45	40	* ecryptfs_get_locked_page
237fead6 MH	41	*
	42	* Get one page from cache or lower f/s, return error otherwise.
	43	*
16a72c45	44	* Returns locked and up-to-date page (if ok), with increased
237fead6 MH	45	* refcnt.
237fead6 MH	46	*/
16a72c45	47	struct page ecryptfs_get_locked_page(struct file file, loff_t index)
237fead6	48	{
237fead6 MH	49	struct dentry *dentry;
	50	struct inode *inode;
	51	struct address_space *mapping;
16a72c45	52	struct page *page;
237fead6	53
bd243a4b	54	dentry = file->f_path.dentry;
237fead6 MH	55	inode = dentry->d_inode;
237fead6 MH	56	mapping = inode->i_mapping;
16a72c45 MH	57	page = read_mapping_page(mapping, index, (void *)file);
	58	if (!IS_ERR(page))
	59	lock_page(page);
	60	return page;
237fead6 MH	61	}
237fead6 MH	62
237fead6 MH	63	/**
	64	* ecryptfs_writepage
	65	* @page: Page that is locked before this call is made
	66	*
	67	* Returns zero on success; non-zero otherwise
	68	*/
	69	static int ecryptfs_writepage(struct page page, struct writeback_control wbc)
	70	{
237fead6 MH	71	int rc;
237fead6 MH	72
0216f7f7	73	rc = ecryptfs_encrypt_page(page);
237fead6 MH	74	if (rc) {
	75	ecryptfs_printk(KERN_WARNING, "Error encrypting "
	76	"page (upper index [0x%.16x])\n", page->index);
	77	ClearPageUptodate(page);
	78	goto out;
	79	}
	80	SetPageUptodate(page);
	81	unlock_page(page);
	82	out:
	83	return rc;
	84	}
	85
e77a56dd MH	86	/**
	87	* Header Extent:
	88	* Octets 0-7: Unencrypted file size (big-endian)
	89	* Octets 8-15: eCryptfs special marker
	90	* Octets 16-19: Flags
	91	* Octet 16: File format version number (between 0 and 255)
	92	* Octets 17-18: Reserved
	93	* Octet 19: Bit 1 (lsb): Reserved
	94	* Bit 2: Encrypted?
	95	* Bits 3-8: Reserved
	96	* Octets 20-23: Header extent size (big-endian)
	97	* Octets 24-25: Number of header extents at front of file
	98	* (big-endian)
	99	* Octet 26: Begin RFC 2440 authentication token packet set
	100	*/
	101	static void set_header_info(char *page_virt,
	102	struct ecryptfs_crypt_stat *crypt_stat)
	103	{
	104	size_t written;
	105	int save_num_header_extents_at_front =
	106	crypt_stat->num_header_extents_at_front;
	107
	108	crypt_stat->num_header_extents_at_front = 1;
	109	ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
	110	crypt_stat->num_header_extents_at_front =
	111	save_num_header_extents_at_front;
	112	}
237fead6	113
bf12be1c MH	114	/**
	115	* ecryptfs_copy_up_encrypted_with_header
	116	* @page: Sort of a ``virtual'' representation of the encrypted lower
	117	* file. The actual lower file does not have the metadata in
	118	* the header. This is locked.
	119	* @crypt_stat: The eCryptfs inode's cryptographic context
	120	*
	121	* The ``view'' is the version of the file that userspace winds up
	122	* seeing, with the header information inserted.
	123	*/
	124	static int
	125	ecryptfs_copy_up_encrypted_with_header(struct page *page,
	126	struct ecryptfs_crypt_stat *crypt_stat)
	127	{
	128	loff_t extent_num_in_page = 0;
	129	loff_t num_extents_per_page = (PAGE_CACHE_SIZE
	130	/ crypt_stat->extent_size);
	131	int rc = 0;
	132
	133	while (extent_num_in_page < num_extents_per_page) {
d6a13c17 MH	134	loff_t view_extent_num = ((((loff_t)page->index)
d6a13c17 MH	135	* num_extents_per_page)
bf12be1c MH	136	+ extent_num_in_page);
	137
	138	if (view_extent_num < crypt_stat->num_header_extents_at_front) {
	139	/* This is a header extent */
	140	char *page_virt;
	141
	142	page_virt = kmap_atomic(page, KM_USER0);
	143	memset(page_virt, 0, PAGE_CACHE_SIZE);
	144	/* TODO: Support more than one header extent */
	145	if (view_extent_num == 0) {
	146	rc = ecryptfs_read_xattr_region(
	147	page_virt, page->mapping->host);
	148	set_header_info(page_virt, crypt_stat);
	149	}
	150	kunmap_atomic(page_virt, KM_USER0);
	151	flush_dcache_page(page);
	152	if (rc) {
bf12be1c MH	153	printk(KERN_ERR "%s: Error reading xattr "
	154	"region; rc = [%d]\n", __FUNCTION__, rc);
	155	goto out;
	156	}
bf12be1c MH	157	} else {
	158	/* This is an encrypted data extent */
	159	loff_t lower_offset =
	160	((view_extent_num -
	161	crypt_stat->num_header_extents_at_front)
	162	* crypt_stat->extent_size);
	163
	164	rc = ecryptfs_read_lower_page_segment(
	165	page, (lower_offset >> PAGE_CACHE_SHIFT),
	166	(lower_offset & ~PAGE_CACHE_MASK),
	167	crypt_stat->extent_size, page->mapping->host);
	168	if (rc) {
	169	printk(KERN_ERR "%s: Error attempting to read "
	170	"extent at offset [%lld] in the lower "
	171	"file; rc = [%d]\n", __FUNCTION__,
	172	lower_offset, rc);
	173	goto out;
	174	}
	175	}
	176	extent_num_in_page++;
	177	}
	178	out:
	179	return rc;
	180	}
	181
237fead6 MH	182	/**
237fead6 MH	183	* ecryptfs_readpage
bf12be1c MH	184	* @file: An eCryptfs file
bf12be1c MH	185	* @page: Page from eCryptfs inode mapping into which to stick the read data
237fead6 MH	186	*
	187	* Read in a page, decrypting if necessary.
	188	*
	189	* Returns zero on success; non-zero on error.
	190	*/
	191	static int ecryptfs_readpage(struct file file, struct page page)
	192	{
bf12be1c MH	193	struct ecryptfs_crypt_stat *crypt_stat =
bf12be1c MH	194	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6	195	int rc = 0;
237fead6	196
237fead6	197	if (!crypt_stat
e2bd99ec MH	198	\|\| !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
e2bd99ec MH	199	\|\| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
237fead6 MH	200	ecryptfs_printk(KERN_DEBUG,
237fead6 MH	201	"Passing through unencrypted page\n");
bf12be1c MH	202	rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
	203	PAGE_CACHE_SIZE,
	204	page->mapping->host);
e77a56dd MH	205	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
e77a56dd MH	206	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
bf12be1c MH	207	rc = ecryptfs_copy_up_encrypted_with_header(page,
	208	crypt_stat);
	209	if (rc) {
	210	printk(KERN_ERR "%s: Error attempting to copy "
	211	"the encrypted content from the lower "
	212	"file whilst inserting the metadata "
	213	"from the xattr into the header; rc = "
	214	"[%d]\n", __FUNCTION__, rc);
	215	goto out;
e77a56dd	216	}
bf12be1c	217
e77a56dd	218	} else {
bf12be1c MH	219	rc = ecryptfs_read_lower_page_segment(
	220	page, page->index, 0, PAGE_CACHE_SIZE,
	221	page->mapping->host);
e77a56dd MH	222	if (rc) {
	223	printk(KERN_ERR "Error reading page; rc = "
	224	"[%d]\n", rc);
	225	goto out;
	226	}
	227	}
237fead6	228	} else {
0216f7f7	229	rc = ecryptfs_decrypt_page(page);
237fead6	230	if (rc) {
237fead6 MH	231	ecryptfs_printk(KERN_ERR, "Error decrypting page; "
	232	"rc = [%d]\n", rc);
	233	goto out;
	234	}
	235	}
237fead6	236	out:
16a72c45 MH	237	if (rc)
	238	ClearPageUptodate(page);
	239	else
	240	SetPageUptodate(page);
237fead6 MH	241	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
	242	page->index);
	243	unlock_page(page);
	244	return rc;
	245	}
	246
dd2a3b7a MH	247	/**
	248	* Called with lower inode mutex held.
	249	*/
237fead6 MH	250	static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
	251	{
	252	struct inode *inode = page->mapping->host;
	253	int end_byte_in_page;
237fead6	254
9d8b8ce5 MH	255	if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
	256	goto out;
	257	end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
	258	if (to > end_byte_in_page)
	259	end_byte_in_page = to;
eebd2aa3	260	zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
237fead6	261	out:
9d8b8ce5	262	return 0;
237fead6 MH	263	}
237fead6 MH	264
7a3f595c	265	/* This function must zero any hole we create */
237fead6 MH	266	static int ecryptfs_prepare_write(struct file file, struct page page,
	267	unsigned from, unsigned to)
	268	{
	269	int rc = 0;
7a3f595c	270	loff_t prev_page_end_size;
237fead6	271
16a72c45	272	if (!PageUptodate(page)) {
bf12be1c MH	273	rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
	274	PAGE_CACHE_SIZE,
	275	page->mapping->host);
16a72c45 MH	276	if (rc) {
	277	printk(KERN_ERR "%s: Error attemping to read lower "
	278	"page segment; rc = [%d]\n", __FUNCTION__, rc);
	279	ClearPageUptodate(page);
	280	goto out;
	281	} else
	282	SetPageUptodate(page);
	283	}
240e2df5	284
7a3f595c ES	285	prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);
	286
	287	/*
	288	* If creating a page or more of holes, zero them out via truncate.
	289	* Note, this will increase i_size.
	290	*/
	291	if (page->index != 0) {
	292	if (prev_page_end_size > i_size_read(page->mapping->host)) {
240e2df5	293	rc = ecryptfs_truncate(file->f_path.dentry,
7a3f595c	294	prev_page_end_size);
240e2df5 MH	295	if (rc) {
	296	printk(KERN_ERR "Error on attempt to "
	297	"truncate to (higher) offset [%lld];"
7a3f595c	298	" rc = [%d]\n", prev_page_end_size, rc);
240e2df5 MH	299	goto out;
240e2df5 MH	300	}
53a2731f	301	}
7a3f595c ES	302	}
	303	/*
	304	* Writing to a new page, and creating a small hole from start of page?
	305	* Zero it out.
	306	*/
	307	if ((i_size_read(page->mapping->host) == prev_page_end_size) &&
	308	(from != 0)) {
eebd2aa3	309	zero_user(page, 0, PAGE_CACHE_SIZE);
53a2731f	310	}
237fead6 MH	311	out:
	312	return rc;
	313	}
	314
237fead6 MH	315	/**
	316	* ecryptfs_write_inode_size_to_header
	317	*
	318	* Writes the lower file size to the first 8 bytes of the header.
	319	*
	320	* Returns zero on success; non-zero on error.
	321	*/
0216f7f7	322	static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
237fead6	323	{
237fead6	324	u64 file_size;
0216f7f7 MH	325	char *file_size_virt;
0216f7f7 MH	326	int rc;
237fead6	327
0216f7f7 MH	328	file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
	329	if (!file_size_virt) {
	330	rc = -ENOMEM;
ae73fc09 MH	331	goto out;
ae73fc09 MH	332	}
0216f7f7	333	file_size = (u64)i_size_read(ecryptfs_inode);
237fead6	334	file_size = cpu_to_be64(file_size);
0216f7f7 MH	335	memcpy(file_size_virt, &file_size, sizeof(u64));
	336	rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
	337	sizeof(u64));
	338	kfree(file_size_virt);
	339	if (rc)
	340	printk(KERN_ERR "%s: Error writing file size to header; "
	341	"rc = [%d]\n", __FUNCTION__, rc);
237fead6 MH	342	out:
	343	return rc;
	344	}
	345
0216f7f7 MH	346	struct kmem_cache *ecryptfs_xattr_cache;
	347
	348	static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
dd2a3b7a MH	349	{
	350	ssize_t size;
	351	void *xattr_virt;
0216f7f7 MH	352	struct dentry *lower_dentry =
	353	ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
	354	struct inode *lower_inode = lower_dentry->d_inode;
dd2a3b7a MH	355	u64 file_size;
	356	int rc;
	357
0216f7f7 MH	358	if (!lower_inode->i_op->getxattr \|\| !lower_inode->i_op->setxattr) {
	359	printk(KERN_WARNING
	360	"No support for setting xattr in lower filesystem\n");
	361	rc = -ENOSYS;
	362	goto out;
	363	}
dd2a3b7a MH	364	xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
	365	if (!xattr_virt) {
	366	printk(KERN_ERR "Out of memory whilst attempting to write "
	367	"inode size to xattr\n");
	368	rc = -ENOMEM;
	369	goto out;
	370	}
0216f7f7 MH	371	mutex_lock(&lower_inode->i_mutex);
	372	size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	373	xattr_virt, PAGE_CACHE_SIZE);
dd2a3b7a MH	374	if (size < 0)
dd2a3b7a MH	375	size = 8;
0216f7f7	376	file_size = (u64)i_size_read(ecryptfs_inode);
dd2a3b7a MH	377	file_size = cpu_to_be64(file_size);
dd2a3b7a MH	378	memcpy(xattr_virt, &file_size, sizeof(u64));
0216f7f7 MH	379	rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	380	xattr_virt, size, 0);
	381	mutex_unlock(&lower_inode->i_mutex);
dd2a3b7a MH	382	if (rc)
	383	printk(KERN_ERR "Error whilst attempting to write inode size "
	384	"to lower file xattr; rc = [%d]\n", rc);
	385	kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
	386	out:
	387	return rc;
	388	}
	389
0216f7f7	390	int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
dd2a3b7a MH	391	{
	392	struct ecryptfs_crypt_stat *crypt_stat;
	393
0216f7f7	394	crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
dd2a3b7a	395	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
0216f7f7	396	return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
dd2a3b7a	397	else
0216f7f7	398	return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
dd2a3b7a MH	399	}
dd2a3b7a MH	400
237fead6 MH	401	/**
	402	* ecryptfs_commit_write
	403	* @file: The eCryptfs file object
	404	* @page: The eCryptfs page
	405	* @from: Ignored (we rotate the page IV on each write)
	406	* @to: Ignored
	407	*
	408	* This is where we encrypt the data and pass the encrypted data to
	409	* the lower filesystem. In OpenPGP-compatible mode, we operate on
	410	* entire underlying packets.
	411	*/
	412	static int ecryptfs_commit_write(struct file file, struct page page,
	413	unsigned from, unsigned to)
	414	{
237fead6	415	loff_t pos;
bf12be1c MH	416	struct inode *ecryptfs_inode = page->mapping->host;
	417	struct ecryptfs_crypt_stat *crypt_stat =
	418	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6 MH	419	int rc;
237fead6 MH	420
e2bd99ec	421	if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
237fead6 MH	422	ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
237fead6 MH	423	"crypt_stat at memory location [%p]\n", crypt_stat);
e2bd99ec	424	crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
237fead6 MH	425	} else
	426	ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
	427	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
	428	"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
	429	to);
bf12be1c	430	/* Fills in zeros if 'to' goes beyond inode size */
237fead6 MH	431	rc = fill_zeros_to_end_of_page(page, to);
	432	if (rc) {
	433	ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
	434	"zeros in page with index = [0x%.16x]\n",
	435	page->index);
	436	goto out;
	437	}
0216f7f7	438	rc = ecryptfs_encrypt_page(page);
237fead6 MH	439	if (rc) {
	440	ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
	441	"index [0x%.16x])\n", page->index);
	442	goto out;
	443	}
d6a13c17	444	pos = (((loff_t)page->index) << PAGE_CACHE_SHIFT) + to;
bf12be1c MH	445	if (pos > i_size_read(ecryptfs_inode)) {
bf12be1c MH	446	i_size_write(ecryptfs_inode, pos);
237fead6	447	ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
bf12be1c	448	"[0x%.16x]\n", i_size_read(ecryptfs_inode));
237fead6	449	}
bf12be1c	450	rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
dd2a3b7a MH	451	if (rc)
	452	printk(KERN_ERR "Error writing inode size to metadata; "
	453	"rc = [%d]\n", rc);
237fead6	454	out:
237fead6 MH	455	return rc;
	456	}
	457
237fead6 MH	458	static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
	459	{
	460	int rc = 0;
	461	struct inode *inode;
	462	struct inode *lower_inode;
	463
	464	inode = (struct inode *)mapping->host;
	465	lower_inode = ecryptfs_inode_to_lower(inode);
	466	if (lower_inode->i_mapping->a_ops->bmap)
	467	rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
	468	block);
	469	return rc;
	470	}
	471
237fead6 MH	472	struct address_space_operations ecryptfs_aops = {
	473	.writepage = ecryptfs_writepage,
	474	.readpage = ecryptfs_readpage,
	475	.prepare_write = ecryptfs_prepare_write,
	476	.commit_write = ecryptfs_commit_write,
	477	.bmap = ecryptfs_bmap,
237fead6	478	};