[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 <[email protected]>
 *
 * 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 <asm/unaligned.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", __func__, 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", __func__,
				       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", __func__, 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;
}

/**
 * ecryptfs_prepare_write
 * @file: The eCryptfs file
 * @page: The eCryptfs page
 * @from: The start byte from which we will write
 * @to: The end byte to which we will write
 *
 * This function must zero any hole we create
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_prepare_write(struct file *file, struct page *page,
				  unsigned from, unsigned to)
{
	loff_t prev_page_end_size;
	int rc = 0;

	if (!PageUptodate(page)) {
		struct ecryptfs_crypt_stat *crypt_stat =
			&ecryptfs_inode_to_private(
				file->f_path.dentry->d_inode)->crypt_stat;

		if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
		    || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
			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",
				       __func__, rc);
				ClearPageUptodate(page);
				goto out;
			} else
				SetPageUptodate(page);
		} 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", __func__, rc);
					ClearPageUptodate(page);
					goto out;
				}
				SetPageUptodate(page);
			} else {
				rc = ecryptfs_read_lower_page_segment(
					page, page->index, 0, PAGE_CACHE_SIZE,
					page->mapping->host);
				if (rc) {
					printk(KERN_ERR "%s: Error reading "
					       "page; rc = [%d]\n",
					       __func__, rc);
					ClearPageUptodate(page);
					goto out;
				}
				SetPageUptodate(page);
			}
		} else {
			rc = ecryptfs_decrypt_page(page);
			if (rc) {
				printk(KERN_ERR "%s: Error decrypting page "
				       "at index [%ld]; rc = [%d]\n",
				       __func__, page->index, rc);
				ClearPageUptodate(page);
				goto out;
			}
			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 "%s: Error on attempt to "
				       "truncate to (higher) offset [%lld];"
				       " rc = [%d]\n", __func__,
				       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)
{
	char *file_size_virt;
	int rc;

	file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
	if (!file_size_virt) {
		rc = -ENOMEM;
		goto out;
	}
	put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
	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", __func__, 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;
	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;
	put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
	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 <[email protected]>
	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>
0a688ad7	35	#include <asm/unaligned.h>
237fead6 MH	36	#include "ecryptfs_kernel.h"
237fead6 MH	37
237fead6	38	/**
16a72c45	39	* ecryptfs_get_locked_page
237fead6 MH	40	*
	41	* Get one page from cache or lower f/s, return error otherwise.
	42	*
16a72c45	43	* Returns locked and up-to-date page (if ok), with increased
237fead6 MH	44	* refcnt.
237fead6 MH	45	*/
16a72c45	46	struct page ecryptfs_get_locked_page(struct file file, loff_t index)
237fead6	47	{
237fead6 MH	48	struct dentry *dentry;
	49	struct inode *inode;
	50	struct address_space *mapping;
16a72c45	51	struct page *page;
237fead6	52
bd243a4b	53	dentry = file->f_path.dentry;
237fead6 MH	54	inode = dentry->d_inode;
237fead6 MH	55	mapping = inode->i_mapping;
16a72c45 MH	56	page = read_mapping_page(mapping, index, (void *)file);
	57	if (!IS_ERR(page))
	58	lock_page(page);
	59	return page;
237fead6 MH	60	}
237fead6 MH	61
237fead6 MH	62	/**
	63	* ecryptfs_writepage
	64	* @page: Page that is locked before this call is made
	65	*
	66	* Returns zero on success; non-zero otherwise
	67	*/
	68	static int ecryptfs_writepage(struct page page, struct writeback_control wbc)
	69	{
237fead6 MH	70	int rc;
237fead6 MH	71
0216f7f7	72	rc = ecryptfs_encrypt_page(page);
237fead6 MH	73	if (rc) {
	74	ecryptfs_printk(KERN_WARNING, "Error encrypting "
	75	"page (upper index [0x%.16x])\n", page->index);
	76	ClearPageUptodate(page);
	77	goto out;
	78	}
	79	SetPageUptodate(page);
	80	unlock_page(page);
	81	out:
	82	return rc;
	83	}
	84
e77a56dd MH	85	/**
	86	* Header Extent:
	87	* Octets 0-7: Unencrypted file size (big-endian)
	88	* Octets 8-15: eCryptfs special marker
	89	* Octets 16-19: Flags
	90	* Octet 16: File format version number (between 0 and 255)
	91	* Octets 17-18: Reserved
	92	* Octet 19: Bit 1 (lsb): Reserved
	93	* Bit 2: Encrypted?
	94	* Bits 3-8: Reserved
	95	* Octets 20-23: Header extent size (big-endian)
	96	* Octets 24-25: Number of header extents at front of file
	97	* (big-endian)
	98	* Octet 26: Begin RFC 2440 authentication token packet set
	99	*/
	100	static void set_header_info(char *page_virt,
	101	struct ecryptfs_crypt_stat *crypt_stat)
	102	{
	103	size_t written;
cc11beff MH	104	size_t save_num_header_bytes_at_front =
cc11beff MH	105	crypt_stat->num_header_bytes_at_front;
e77a56dd	106
cc11beff MH	107	crypt_stat->num_header_bytes_at_front =
cc11beff MH	108	ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
e77a56dd	109	ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
cc11beff MH	110	crypt_stat->num_header_bytes_at_front =
cc11beff MH	111	save_num_header_bytes_at_front;
e77a56dd	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	136	+ extent_num_in_page);
cc11beff MH	137	size_t num_header_extents_at_front =
	138	(crypt_stat->num_header_bytes_at_front
	139	/ crypt_stat->extent_size);
bf12be1c	140
cc11beff	141	if (view_extent_num < num_header_extents_at_front) {
bf12be1c MH	142	/* This is a header extent */
	143	char *page_virt;
	144
	145	page_virt = kmap_atomic(page, KM_USER0);
	146	memset(page_virt, 0, PAGE_CACHE_SIZE);
	147	/* TODO: Support more than one header extent */
	148	if (view_extent_num == 0) {
	149	rc = ecryptfs_read_xattr_region(
	150	page_virt, page->mapping->host);
	151	set_header_info(page_virt, crypt_stat);
	152	}
	153	kunmap_atomic(page_virt, KM_USER0);
	154	flush_dcache_page(page);
	155	if (rc) {
bf12be1c	156	printk(KERN_ERR "%s: Error reading xattr "
18d1dbf1	157	"region; rc = [%d]\n", __func__, rc);
bf12be1c MH	158	goto out;
bf12be1c MH	159	}
bf12be1c MH	160	} else {
	161	/* This is an encrypted data extent */
	162	loff_t lower_offset =
cc11beff MH	163	((view_extent_num * crypt_stat->extent_size)
cc11beff MH	164	- crypt_stat->num_header_bytes_at_front);
bf12be1c MH	165
	166	rc = ecryptfs_read_lower_page_segment(
	167	page, (lower_offset >> PAGE_CACHE_SHIFT),
	168	(lower_offset & ~PAGE_CACHE_MASK),
	169	crypt_stat->extent_size, page->mapping->host);
	170	if (rc) {
	171	printk(KERN_ERR "%s: Error attempting to read "
	172	"extent at offset [%lld] in the lower "
18d1dbf1	173	"file; rc = [%d]\n", __func__,
bf12be1c MH	174	lower_offset, rc);
	175	goto out;
	176	}
	177	}
	178	extent_num_in_page++;
	179	}
	180	out:
	181	return rc;
	182	}
	183
237fead6 MH	184	/**
237fead6 MH	185	* ecryptfs_readpage
bf12be1c MH	186	* @file: An eCryptfs file
bf12be1c MH	187	* @page: Page from eCryptfs inode mapping into which to stick the read data
237fead6 MH	188	*
	189	* Read in a page, decrypting if necessary.
	190	*
	191	* Returns zero on success; non-zero on error.
	192	*/
	193	static int ecryptfs_readpage(struct file file, struct page page)
	194	{
bf12be1c MH	195	struct ecryptfs_crypt_stat *crypt_stat =
bf12be1c MH	196	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6	197	int rc = 0;
237fead6	198
237fead6	199	if (!crypt_stat
e2bd99ec MH	200	\|\| !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
e2bd99ec MH	201	\|\| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
237fead6 MH	202	ecryptfs_printk(KERN_DEBUG,
237fead6 MH	203	"Passing through unencrypted page\n");
bf12be1c MH	204	rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
	205	PAGE_CACHE_SIZE,
	206	page->mapping->host);
e77a56dd MH	207	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
e77a56dd MH	208	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
bf12be1c MH	209	rc = ecryptfs_copy_up_encrypted_with_header(page,
	210	crypt_stat);
	211	if (rc) {
	212	printk(KERN_ERR "%s: Error attempting to copy "
	213	"the encrypted content from the lower "
	214	"file whilst inserting the metadata "
	215	"from the xattr into the header; rc = "
18d1dbf1	216	"[%d]\n", __func__, rc);
bf12be1c	217	goto out;
e77a56dd	218	}
bf12be1c	219
e77a56dd	220	} else {
bf12be1c MH	221	rc = ecryptfs_read_lower_page_segment(
	222	page, page->index, 0, PAGE_CACHE_SIZE,
	223	page->mapping->host);
e77a56dd MH	224	if (rc) {
	225	printk(KERN_ERR "Error reading page; rc = "
	226	"[%d]\n", rc);
	227	goto out;
	228	}
	229	}
237fead6	230	} else {
0216f7f7	231	rc = ecryptfs_decrypt_page(page);
237fead6	232	if (rc) {
237fead6 MH	233	ecryptfs_printk(KERN_ERR, "Error decrypting page; "
	234	"rc = [%d]\n", rc);
	235	goto out;
	236	}
	237	}
237fead6	238	out:
16a72c45 MH	239	if (rc)
	240	ClearPageUptodate(page);
	241	else
	242	SetPageUptodate(page);
237fead6 MH	243	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
	244	page->index);
	245	unlock_page(page);
	246	return rc;
	247	}
	248
dd2a3b7a MH	249	/**
	250	* Called with lower inode mutex held.
	251	*/
237fead6 MH	252	static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
	253	{
	254	struct inode *inode = page->mapping->host;
	255	int end_byte_in_page;
237fead6	256
9d8b8ce5 MH	257	if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
	258	goto out;
	259	end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
	260	if (to > end_byte_in_page)
	261	end_byte_in_page = to;
eebd2aa3	262	zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
237fead6	263	out:
9d8b8ce5	264	return 0;
237fead6 MH	265	}
237fead6 MH	266
e4465fda MH	267	/**
	268	* ecryptfs_prepare_write
	269	* @file: The eCryptfs file
	270	* @page: The eCryptfs page
	271	* @from: The start byte from which we will write
	272	* @to: The end byte to which we will write
	273	*
	274	* This function must zero any hole we create
	275	*
	276	* Returns zero on success; non-zero otherwise
	277	*/
237fead6 MH	278	static int ecryptfs_prepare_write(struct file file, struct page page,
	279	unsigned from, unsigned to)
	280	{
7a3f595c	281	loff_t prev_page_end_size;
e4465fda	282	int rc = 0;
237fead6	283
16a72c45	284	if (!PageUptodate(page)) {
e4465fda MH	285	struct ecryptfs_crypt_stat *crypt_stat =
	286	&ecryptfs_inode_to_private(
	287	file->f_path.dentry->d_inode)->crypt_stat;
	288
	289	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
	290	\|\| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
	291	rc = ecryptfs_read_lower_page_segment(
	292	page, page->index, 0, PAGE_CACHE_SIZE,
	293	page->mapping->host);
	294	if (rc) {
	295	printk(KERN_ERR "%s: Error attemping to read "
	296	"lower page segment; rc = [%d]\n",
18d1dbf1	297	__func__, rc);
e4465fda MH	298	ClearPageUptodate(page);
	299	goto out;
	300	} else
	301	SetPageUptodate(page);
	302	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
	303	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
	304	rc = ecryptfs_copy_up_encrypted_with_header(
	305	page, crypt_stat);
	306	if (rc) {
	307	printk(KERN_ERR "%s: Error attempting "
	308	"to copy the encrypted content "
	309	"from the lower file whilst "
	310	"inserting the metadata from "
	311	"the xattr into the header; rc "
18d1dbf1	312	"= [%d]\n", __func__, rc);
e4465fda MH	313	ClearPageUptodate(page);
	314	goto out;
	315	}
	316	SetPageUptodate(page);
	317	} else {
	318	rc = ecryptfs_read_lower_page_segment(
	319	page, page->index, 0, PAGE_CACHE_SIZE,
	320	page->mapping->host);
	321	if (rc) {
	322	printk(KERN_ERR "%s: Error reading "
	323	"page; rc = [%d]\n",
18d1dbf1	324	__func__, rc);
e4465fda MH	325	ClearPageUptodate(page);
	326	goto out;
	327	}
	328	SetPageUptodate(page);
	329	}
	330	} else {
	331	rc = ecryptfs_decrypt_page(page);
	332	if (rc) {
	333	printk(KERN_ERR "%s: Error decrypting page "
	334	"at index [%ld]; rc = [%d]\n",
18d1dbf1	335	__func__, page->index, rc);
e4465fda MH	336	ClearPageUptodate(page);
	337	goto out;
	338	}
16a72c45	339	SetPageUptodate(page);
e4465fda	340	}
16a72c45	341	}
7a3f595c	342	prev_page_end_size = ((loff_t)page->index << PAGE_CACHE_SHIFT);
e4465fda MH	343	/* If creating a page or more of holes, zero them out via truncate.
e4465fda MH	344	* Note, this will increase i_size. */
7a3f595c ES	345	if (page->index != 0) {
7a3f595c ES	346	if (prev_page_end_size > i_size_read(page->mapping->host)) {
240e2df5	347	rc = ecryptfs_truncate(file->f_path.dentry,
7a3f595c	348	prev_page_end_size);
240e2df5	349	if (rc) {
e4465fda	350	printk(KERN_ERR "%s: Error on attempt to "
240e2df5	351	"truncate to (higher) offset [%lld];"
18d1dbf1	352	" rc = [%d]\n", __func__,
e4465fda	353	prev_page_end_size, rc);
240e2df5 MH	354	goto out;
240e2df5 MH	355	}
53a2731f	356	}
7a3f595c	357	}
e4465fda MH	358	/* Writing to a new page, and creating a small hole from start
	359	* of page? Zero it out. */
	360	if ((i_size_read(page->mapping->host) == prev_page_end_size)
	361	&& (from != 0))
eebd2aa3	362	zero_user(page, 0, PAGE_CACHE_SIZE);
237fead6 MH	363	out:
	364	return rc;
	365	}
	366
237fead6 MH	367	/**
	368	* ecryptfs_write_inode_size_to_header
	369	*
	370	* Writes the lower file size to the first 8 bytes of the header.
	371	*
	372	* Returns zero on success; non-zero on error.
	373	*/
0216f7f7	374	static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
237fead6	375	{
0216f7f7 MH	376	char *file_size_virt;
0216f7f7 MH	377	int rc;
237fead6	378
0216f7f7 MH	379	file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
	380	if (!file_size_virt) {
	381	rc = -ENOMEM;
ae73fc09 MH	382	goto out;
ae73fc09 MH	383	}
0a688ad7	384	put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
0216f7f7 MH	385	rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
	386	sizeof(u64));
	387	kfree(file_size_virt);
	388	if (rc)
	389	printk(KERN_ERR "%s: Error writing file size to header; "
18d1dbf1	390	"rc = [%d]\n", __func__, rc);
237fead6 MH	391	out:
	392	return rc;
	393	}
	394
0216f7f7 MH	395	struct kmem_cache *ecryptfs_xattr_cache;
	396
	397	static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
dd2a3b7a MH	398	{
	399	ssize_t size;
	400	void *xattr_virt;
0216f7f7 MH	401	struct dentry *lower_dentry =
	402	ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
	403	struct inode *lower_inode = lower_dentry->d_inode;
dd2a3b7a MH	404	int rc;
dd2a3b7a MH	405
0216f7f7 MH	406	if (!lower_inode->i_op->getxattr \|\| !lower_inode->i_op->setxattr) {
	407	printk(KERN_WARNING
	408	"No support for setting xattr in lower filesystem\n");
	409	rc = -ENOSYS;
	410	goto out;
	411	}
dd2a3b7a MH	412	xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
	413	if (!xattr_virt) {
	414	printk(KERN_ERR "Out of memory whilst attempting to write "
	415	"inode size to xattr\n");
	416	rc = -ENOMEM;
	417	goto out;
	418	}
0216f7f7 MH	419	mutex_lock(&lower_inode->i_mutex);
	420	size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	421	xattr_virt, PAGE_CACHE_SIZE);
dd2a3b7a MH	422	if (size < 0)
dd2a3b7a MH	423	size = 8;
0a688ad7	424	put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
0216f7f7 MH	425	rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	426	xattr_virt, size, 0);
	427	mutex_unlock(&lower_inode->i_mutex);
dd2a3b7a MH	428	if (rc)
	429	printk(KERN_ERR "Error whilst attempting to write inode size "
	430	"to lower file xattr; rc = [%d]\n", rc);
	431	kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
	432	out:
	433	return rc;
	434	}
	435
0216f7f7	436	int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
dd2a3b7a MH	437	{
	438	struct ecryptfs_crypt_stat *crypt_stat;
	439
0216f7f7	440	crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
dd2a3b7a	441	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
0216f7f7	442	return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
dd2a3b7a	443	else
0216f7f7	444	return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
dd2a3b7a MH	445	}
dd2a3b7a MH	446
237fead6 MH	447	/**
	448	* ecryptfs_commit_write
	449	* @file: The eCryptfs file object
	450	* @page: The eCryptfs page
	451	* @from: Ignored (we rotate the page IV on each write)
	452	* @to: Ignored
	453	*
	454	* This is where we encrypt the data and pass the encrypted data to
	455	* the lower filesystem. In OpenPGP-compatible mode, we operate on
	456	* entire underlying packets.
	457	*/
	458	static int ecryptfs_commit_write(struct file file, struct page page,
	459	unsigned from, unsigned to)
	460	{
237fead6	461	loff_t pos;
bf12be1c MH	462	struct inode *ecryptfs_inode = page->mapping->host;
	463	struct ecryptfs_crypt_stat *crypt_stat =
	464	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6 MH	465	int rc;
237fead6 MH	466
e2bd99ec	467	if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
237fead6 MH	468	ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
237fead6 MH	469	"crypt_stat at memory location [%p]\n", crypt_stat);
e2bd99ec	470	crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
237fead6 MH	471	} else
	472	ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
	473	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
	474	"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
	475	to);
bf12be1c	476	/* Fills in zeros if 'to' goes beyond inode size */
237fead6 MH	477	rc = fill_zeros_to_end_of_page(page, to);
	478	if (rc) {
	479	ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
	480	"zeros in page with index = [0x%.16x]\n",
	481	page->index);
	482	goto out;
	483	}
0216f7f7	484	rc = ecryptfs_encrypt_page(page);
237fead6 MH	485	if (rc) {
	486	ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
	487	"index [0x%.16x])\n", page->index);
	488	goto out;
	489	}
d6a13c17	490	pos = (((loff_t)page->index) << PAGE_CACHE_SHIFT) + to;
bf12be1c MH	491	if (pos > i_size_read(ecryptfs_inode)) {
bf12be1c MH	492	i_size_write(ecryptfs_inode, pos);
237fead6	493	ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
bf12be1c	494	"[0x%.16x]\n", i_size_read(ecryptfs_inode));
237fead6	495	}
bf12be1c	496	rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
dd2a3b7a MH	497	if (rc)
	498	printk(KERN_ERR "Error writing inode size to metadata; "
	499	"rc = [%d]\n", rc);
237fead6	500	out:
237fead6 MH	501	return rc;
	502	}
	503
237fead6 MH	504	static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
	505	{
	506	int rc = 0;
	507	struct inode *inode;
	508	struct inode *lower_inode;
	509
	510	inode = (struct inode *)mapping->host;
	511	lower_inode = ecryptfs_inode_to_lower(inode);
	512	if (lower_inode->i_mapping->a_ops->bmap)
	513	rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
	514	block);
	515	return rc;
	516	}
	517
237fead6 MH	518	struct address_space_operations ecryptfs_aops = {
	519	.writepage = ecryptfs_writepage,
	520	.readpage = ecryptfs_readpage,
	521	.prepare_write = ecryptfs_prepare_write,
	522	.commit_write = ecryptfs_commit_write,
	523	.bmap = ecryptfs_bmap,
237fead6	524	};