[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"

/**
 * 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;
	size_t save_num_header_bytes_at_front =
		crypt_stat->num_header_bytes_at_front;

	crypt_stat->num_header_bytes_at_front =
		ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
	ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
	crypt_stat->num_header_bytes_at_front =
		save_num_header_bytes_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);
		size_t num_header_extents_at_front =
			(crypt_stat->num_header_bytes_at_front
			 / crypt_stat->extent_size);

		if (view_extent_num < 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->extent_size)
				 - crypt_stat->num_header_bytes_at_front);

			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
237fead6	37	/**
16a72c45	38	* ecryptfs_get_locked_page
237fead6 MH	39	*
	40	* Get one page from cache or lower f/s, return error otherwise.
	41	*
16a72c45	42	* Returns locked and up-to-date page (if ok), with increased
237fead6 MH	43	* refcnt.
237fead6 MH	44	*/
16a72c45	45	struct page ecryptfs_get_locked_page(struct file file, loff_t index)
237fead6	46	{
237fead6 MH	47	struct dentry *dentry;
	48	struct inode *inode;
	49	struct address_space *mapping;
16a72c45	50	struct page *page;
237fead6	51
bd243a4b	52	dentry = file->f_path.dentry;
237fead6 MH	53	inode = dentry->d_inode;
237fead6 MH	54	mapping = inode->i_mapping;
16a72c45 MH	55	page = read_mapping_page(mapping, index, (void *)file);
	56	if (!IS_ERR(page))
	57	lock_page(page);
	58	return page;
237fead6 MH	59	}
237fead6 MH	60
237fead6 MH	61	/**
	62	* ecryptfs_writepage
	63	* @page: Page that is locked before this call is made
	64	*
	65	* Returns zero on success; non-zero otherwise
	66	*/
	67	static int ecryptfs_writepage(struct page page, struct writeback_control wbc)
	68	{
237fead6 MH	69	int rc;
237fead6 MH	70
0216f7f7	71	rc = ecryptfs_encrypt_page(page);
237fead6 MH	72	if (rc) {
	73	ecryptfs_printk(KERN_WARNING, "Error encrypting "
	74	"page (upper index [0x%.16x])\n", page->index);
	75	ClearPageUptodate(page);
	76	goto out;
	77	}
	78	SetPageUptodate(page);
	79	unlock_page(page);
	80	out:
	81	return rc;
	82	}
	83
e77a56dd MH	84	/**
	85	* Header Extent:
	86	* Octets 0-7: Unencrypted file size (big-endian)
	87	* Octets 8-15: eCryptfs special marker
	88	* Octets 16-19: Flags
	89	* Octet 16: File format version number (between 0 and 255)
	90	* Octets 17-18: Reserved
	91	* Octet 19: Bit 1 (lsb): Reserved
	92	* Bit 2: Encrypted?
	93	* Bits 3-8: Reserved
	94	* Octets 20-23: Header extent size (big-endian)
	95	* Octets 24-25: Number of header extents at front of file
	96	* (big-endian)
	97	* Octet 26: Begin RFC 2440 authentication token packet set
	98	*/
	99	static void set_header_info(char *page_virt,
	100	struct ecryptfs_crypt_stat *crypt_stat)
	101	{
	102	size_t written;
cc11beff MH	103	size_t save_num_header_bytes_at_front =
cc11beff MH	104	crypt_stat->num_header_bytes_at_front;
e77a56dd	105
cc11beff MH	106	crypt_stat->num_header_bytes_at_front =
cc11beff MH	107	ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
e77a56dd	108	ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
cc11beff MH	109	crypt_stat->num_header_bytes_at_front =
cc11beff MH	110	save_num_header_bytes_at_front;
e77a56dd	111	}
237fead6	112
bf12be1c MH	113	/**
	114	* ecryptfs_copy_up_encrypted_with_header
	115	* @page: Sort of a ``virtual'' representation of the encrypted lower
	116	* file. The actual lower file does not have the metadata in
	117	* the header. This is locked.
	118	* @crypt_stat: The eCryptfs inode's cryptographic context
	119	*
	120	* The ``view'' is the version of the file that userspace winds up
	121	* seeing, with the header information inserted.
	122	*/
	123	static int
	124	ecryptfs_copy_up_encrypted_with_header(struct page *page,
	125	struct ecryptfs_crypt_stat *crypt_stat)
	126	{
	127	loff_t extent_num_in_page = 0;
	128	loff_t num_extents_per_page = (PAGE_CACHE_SIZE
	129	/ crypt_stat->extent_size);
	130	int rc = 0;
	131
	132	while (extent_num_in_page < num_extents_per_page) {
d6a13c17 MH	133	loff_t view_extent_num = ((((loff_t)page->index)
d6a13c17 MH	134	* num_extents_per_page)
bf12be1c	135	+ extent_num_in_page);
cc11beff MH	136	size_t num_header_extents_at_front =
	137	(crypt_stat->num_header_bytes_at_front
	138	/ crypt_stat->extent_size);
bf12be1c	139
cc11beff	140	if (view_extent_num < num_header_extents_at_front) {
bf12be1c MH	141	/* This is a header extent */
	142	char *page_virt;
	143
	144	page_virt = kmap_atomic(page, KM_USER0);
	145	memset(page_virt, 0, PAGE_CACHE_SIZE);
	146	/* TODO: Support more than one header extent */
	147	if (view_extent_num == 0) {
	148	rc = ecryptfs_read_xattr_region(
	149	page_virt, page->mapping->host);
	150	set_header_info(page_virt, crypt_stat);
	151	}
	152	kunmap_atomic(page_virt, KM_USER0);
	153	flush_dcache_page(page);
	154	if (rc) {
bf12be1c MH	155	printk(KERN_ERR "%s: Error reading xattr "
	156	"region; rc = [%d]\n", __FUNCTION__, rc);
	157	goto out;
	158	}
bf12be1c MH	159	} else {
	160	/* This is an encrypted data extent */
	161	loff_t lower_offset =
cc11beff MH	162	((view_extent_num * crypt_stat->extent_size)
cc11beff MH	163	- crypt_stat->num_header_bytes_at_front);
bf12be1c MH	164
	165	rc = ecryptfs_read_lower_page_segment(
	166	page, (lower_offset >> PAGE_CACHE_SHIFT),
	167	(lower_offset & ~PAGE_CACHE_MASK),
	168	crypt_stat->extent_size, page->mapping->host);
	169	if (rc) {
	170	printk(KERN_ERR "%s: Error attempting to read "
	171	"extent at offset [%lld] in the lower "
	172	"file; rc = [%d]\n", __FUNCTION__,
	173	lower_offset, rc);
	174	goto out;
	175	}
	176	}
	177	extent_num_in_page++;
	178	}
	179	out:
	180	return rc;
	181	}
	182
237fead6 MH	183	/**
237fead6 MH	184	* ecryptfs_readpage
bf12be1c MH	185	* @file: An eCryptfs file
bf12be1c MH	186	* @page: Page from eCryptfs inode mapping into which to stick the read data
237fead6 MH	187	*
	188	* Read in a page, decrypting if necessary.
	189	*
	190	* Returns zero on success; non-zero on error.
	191	*/
	192	static int ecryptfs_readpage(struct file file, struct page page)
	193	{
bf12be1c MH	194	struct ecryptfs_crypt_stat *crypt_stat =
bf12be1c MH	195	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6	196	int rc = 0;
237fead6	197
237fead6	198	if (!crypt_stat
e2bd99ec MH	199	\|\| !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
e2bd99ec MH	200	\|\| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
237fead6 MH	201	ecryptfs_printk(KERN_DEBUG,
237fead6 MH	202	"Passing through unencrypted page\n");
bf12be1c MH	203	rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
	204	PAGE_CACHE_SIZE,
	205	page->mapping->host);
e77a56dd MH	206	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
e77a56dd MH	207	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
bf12be1c MH	208	rc = ecryptfs_copy_up_encrypted_with_header(page,
	209	crypt_stat);
	210	if (rc) {
	211	printk(KERN_ERR "%s: Error attempting to copy "
	212	"the encrypted content from the lower "
	213	"file whilst inserting the metadata "
	214	"from the xattr into the header; rc = "
	215	"[%d]\n", __FUNCTION__, rc);
	216	goto out;
e77a56dd	217	}
bf12be1c	218
e77a56dd	219	} else {
bf12be1c MH	220	rc = ecryptfs_read_lower_page_segment(
	221	page, page->index, 0, PAGE_CACHE_SIZE,
	222	page->mapping->host);
e77a56dd MH	223	if (rc) {
	224	printk(KERN_ERR "Error reading page; rc = "
	225	"[%d]\n", rc);
	226	goto out;
	227	}
	228	}
237fead6	229	} else {
0216f7f7	230	rc = ecryptfs_decrypt_page(page);
237fead6	231	if (rc) {
237fead6 MH	232	ecryptfs_printk(KERN_ERR, "Error decrypting page; "
	233	"rc = [%d]\n", rc);
	234	goto out;
	235	}
	236	}
237fead6	237	out:
16a72c45 MH	238	if (rc)
	239	ClearPageUptodate(page);
	240	else
	241	SetPageUptodate(page);
237fead6 MH	242	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
	243	page->index);
	244	unlock_page(page);
	245	return rc;
	246	}
	247
dd2a3b7a MH	248	/**
	249	* Called with lower inode mutex held.
	250	*/
237fead6 MH	251	static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
	252	{
	253	struct inode *inode = page->mapping->host;
	254	int end_byte_in_page;
237fead6	255
9d8b8ce5 MH	256	if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
	257	goto out;
	258	end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
	259	if (to > end_byte_in_page)
	260	end_byte_in_page = to;
eebd2aa3	261	zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
237fead6	262	out:
9d8b8ce5	263	return 0;
237fead6 MH	264	}
237fead6 MH	265
7a3f595c	266	/* This function must zero any hole we create */
237fead6 MH	267	static int ecryptfs_prepare_write(struct file file, struct page page,
	268	unsigned from, unsigned to)
	269	{
	270	int rc = 0;
7a3f595c	271	loff_t prev_page_end_size;
237fead6	272
16a72c45	273	if (!PageUptodate(page)) {
bf12be1c MH	274	rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
	275	PAGE_CACHE_SIZE,
	276	page->mapping->host);
16a72c45 MH	277	if (rc) {
	278	printk(KERN_ERR "%s: Error attemping to read lower "
	279	"page segment; rc = [%d]\n", __FUNCTION__, rc);
	280	ClearPageUptodate(page);
	281	goto out;
	282	} else
	283	SetPageUptodate(page);
	284	}
240e2df5	285
7a3f595c ES	286	prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);
	287
	288	/*
	289	* If creating a page or more of holes, zero them out via truncate.
	290	* Note, this will increase i_size.
	291	*/
	292	if (page->index != 0) {
	293	if (prev_page_end_size > i_size_read(page->mapping->host)) {
240e2df5	294	rc = ecryptfs_truncate(file->f_path.dentry,
7a3f595c	295	prev_page_end_size);
240e2df5 MH	296	if (rc) {
	297	printk(KERN_ERR "Error on attempt to "
	298	"truncate to (higher) offset [%lld];"
7a3f595c	299	" rc = [%d]\n", prev_page_end_size, rc);
240e2df5 MH	300	goto out;
240e2df5 MH	301	}
53a2731f	302	}
7a3f595c ES	303	}
	304	/*
	305	* Writing to a new page, and creating a small hole from start of page?
	306	* Zero it out.
	307	*/
	308	if ((i_size_read(page->mapping->host) == prev_page_end_size) &&
	309	(from != 0)) {
eebd2aa3	310	zero_user(page, 0, PAGE_CACHE_SIZE);
53a2731f	311	}
237fead6 MH	312	out:
	313	return rc;
	314	}
	315
237fead6 MH	316	/**
	317	* ecryptfs_write_inode_size_to_header
	318	*
	319	* Writes the lower file size to the first 8 bytes of the header.
	320	*
	321	* Returns zero on success; non-zero on error.
	322	*/
0216f7f7	323	static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
237fead6	324	{
237fead6	325	u64 file_size;
0216f7f7 MH	326	char *file_size_virt;
0216f7f7 MH	327	int rc;
237fead6	328
0216f7f7 MH	329	file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
	330	if (!file_size_virt) {
	331	rc = -ENOMEM;
ae73fc09 MH	332	goto out;
ae73fc09 MH	333	}
0216f7f7	334	file_size = (u64)i_size_read(ecryptfs_inode);
237fead6	335	file_size = cpu_to_be64(file_size);
0216f7f7 MH	336	memcpy(file_size_virt, &file_size, sizeof(u64));
	337	rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
	338	sizeof(u64));
	339	kfree(file_size_virt);
	340	if (rc)
	341	printk(KERN_ERR "%s: Error writing file size to header; "
	342	"rc = [%d]\n", __FUNCTION__, rc);
237fead6 MH	343	out:
	344	return rc;
	345	}
	346
0216f7f7 MH	347	struct kmem_cache *ecryptfs_xattr_cache;
	348
	349	static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
dd2a3b7a MH	350	{
	351	ssize_t size;
	352	void *xattr_virt;
0216f7f7 MH	353	struct dentry *lower_dentry =
	354	ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
	355	struct inode *lower_inode = lower_dentry->d_inode;
dd2a3b7a MH	356	u64 file_size;
	357	int rc;
	358
0216f7f7 MH	359	if (!lower_inode->i_op->getxattr \|\| !lower_inode->i_op->setxattr) {
	360	printk(KERN_WARNING
	361	"No support for setting xattr in lower filesystem\n");
	362	rc = -ENOSYS;
	363	goto out;
	364	}
dd2a3b7a MH	365	xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
	366	if (!xattr_virt) {
	367	printk(KERN_ERR "Out of memory whilst attempting to write "
	368	"inode size to xattr\n");
	369	rc = -ENOMEM;
	370	goto out;
	371	}
0216f7f7 MH	372	mutex_lock(&lower_inode->i_mutex);
	373	size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	374	xattr_virt, PAGE_CACHE_SIZE);
dd2a3b7a MH	375	if (size < 0)
dd2a3b7a MH	376	size = 8;
0216f7f7	377	file_size = (u64)i_size_read(ecryptfs_inode);
dd2a3b7a MH	378	file_size = cpu_to_be64(file_size);
dd2a3b7a MH	379	memcpy(xattr_virt, &file_size, sizeof(u64));
0216f7f7 MH	380	rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	381	xattr_virt, size, 0);
	382	mutex_unlock(&lower_inode->i_mutex);
dd2a3b7a MH	383	if (rc)
	384	printk(KERN_ERR "Error whilst attempting to write inode size "
	385	"to lower file xattr; rc = [%d]\n", rc);
	386	kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
	387	out:
	388	return rc;
	389	}
	390
0216f7f7	391	int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
dd2a3b7a MH	392	{
	393	struct ecryptfs_crypt_stat *crypt_stat;
	394
0216f7f7	395	crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
dd2a3b7a	396	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
0216f7f7	397	return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
dd2a3b7a	398	else
0216f7f7	399	return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
dd2a3b7a MH	400	}
dd2a3b7a MH	401
237fead6 MH	402	/**
	403	* ecryptfs_commit_write
	404	* @file: The eCryptfs file object
	405	* @page: The eCryptfs page
	406	* @from: Ignored (we rotate the page IV on each write)
	407	* @to: Ignored
	408	*
	409	* This is where we encrypt the data and pass the encrypted data to
	410	* the lower filesystem. In OpenPGP-compatible mode, we operate on
	411	* entire underlying packets.
	412	*/
	413	static int ecryptfs_commit_write(struct file file, struct page page,
	414	unsigned from, unsigned to)
	415	{
237fead6	416	loff_t pos;
bf12be1c MH	417	struct inode *ecryptfs_inode = page->mapping->host;
	418	struct ecryptfs_crypt_stat *crypt_stat =
	419	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6 MH	420	int rc;
237fead6 MH	421
e2bd99ec	422	if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
237fead6 MH	423	ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
237fead6 MH	424	"crypt_stat at memory location [%p]\n", crypt_stat);
e2bd99ec	425	crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
237fead6 MH	426	} else
	427	ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
	428	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
	429	"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
	430	to);
bf12be1c	431	/* Fills in zeros if 'to' goes beyond inode size */
237fead6 MH	432	rc = fill_zeros_to_end_of_page(page, to);
	433	if (rc) {
	434	ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
	435	"zeros in page with index = [0x%.16x]\n",
	436	page->index);
	437	goto out;
	438	}
0216f7f7	439	rc = ecryptfs_encrypt_page(page);
237fead6 MH	440	if (rc) {
	441	ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
	442	"index [0x%.16x])\n", page->index);
	443	goto out;
	444	}
d6a13c17	445	pos = (((loff_t)page->index) << PAGE_CACHE_SHIFT) + to;
bf12be1c MH	446	if (pos > i_size_read(ecryptfs_inode)) {
bf12be1c MH	447	i_size_write(ecryptfs_inode, pos);
237fead6	448	ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
bf12be1c	449	"[0x%.16x]\n", i_size_read(ecryptfs_inode));
237fead6	450	}
bf12be1c	451	rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
dd2a3b7a MH	452	if (rc)
	453	printk(KERN_ERR "Error writing inode size to metadata; "
	454	"rc = [%d]\n", rc);
237fead6	455	out:
237fead6 MH	456	return rc;
	457	}
	458
237fead6 MH	459	static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
	460	{
	461	int rc = 0;
	462	struct inode *inode;
	463	struct inode *lower_inode;
	464
	465	inode = (struct inode *)mapping->host;
	466	lower_inode = ecryptfs_inode_to_lower(inode);
	467	if (lower_inode->i_mapping->a_ops->bmap)
	468	rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
	469	block);
	470	return rc;
	471	}
	472
237fead6 MH	473	struct address_space_operations ecryptfs_aops = {
	474	.writepage = ecryptfs_writepage,
	475	.readpage = ecryptfs_readpage,
	476	.prepare_write = ecryptfs_prepare_write,
	477	.commit_write = ecryptfs_commit_write,
	478	.bmap = ecryptfs_bmap,
237fead6	479	};