[net-next-2.6.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 <linux/slab.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_write_begin
 * @file: The eCryptfs file
 * @mapping: The eCryptfs object
 * @pos: The file offset at which to start writing
 * @len: Length of the write
 * @flags: Various flags
 * @pagep: Pointer to return the page
 * @fsdata: Pointer to return fs data (unused)
 *
 * This function must zero any hole we create
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_write_begin(struct file *file,
			struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
{
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	struct page *page;
	loff_t prev_page_end_size;
	int rc = 0;

	page = grab_cache_page_write_begin(mapping, index, flags);
	if (!page)
		return -ENOMEM;
	*pagep = page;

	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, index, 0, PAGE_CACHE_SIZE, 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, index, 0, PAGE_CACHE_SIZE,
					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)index << PAGE_CACHE_SHIFT);
	/* If creating a page or more of holes, zero them out via truncate.
	 * Note, this will increase i_size. */
	if (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(mapping->host) == prev_page_end_size)
	    && (pos != 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 < 0)
		printk(KERN_ERR "%s: Error writing file size to header; "
		       "rc = [%d]\n", __func__, rc);
	else
		rc = 0;
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;
	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
	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_write_end
 * @file: The eCryptfs file object
 * @mapping: The eCryptfs object
 * @pos: The file position
 * @len: The length of the data (unused)
 * @copied: The amount of data copied
 * @page: The eCryptfs page
 * @fsdata: The fsdata (unused)
 *
 * 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_write_end(struct file *file,
			struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
{
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
	unsigned to = from + copied;
	struct inode *ecryptfs_inode = 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", index, to);
	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
		rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0,
						       to);
		if (!rc) {
			rc = copied;
			fsstack_copy_inode_size(ecryptfs_inode,
				ecryptfs_inode_to_lower(ecryptfs_inode));
		}
		goto out;
	}
	/* 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", index);
		goto out;
	}
	rc = ecryptfs_encrypt_page(page);
	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
				"index [0x%.16x])\n", index);
		goto out;
	}
	if (pos + copied > i_size_read(ecryptfs_inode)) {
		i_size_write(ecryptfs_inode, pos + copied);
		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);
	else
		rc = copied;
out:
	unlock_page(page);
	page_cache_release(page);
	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;
}

const struct address_space_operations ecryptfs_aops = {
	.writepage = ecryptfs_writepage,
	.readpage = ecryptfs_readpage,
	.write_begin = ecryptfs_write_begin,
	.write_end = ecryptfs_write_end,
	.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>
5a0e3ad6	35	#include <linux/slab.h>
0a688ad7	36	#include <asm/unaligned.h>
237fead6 MH	37	#include "ecryptfs_kernel.h"
237fead6 MH	38
237fead6	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;
cc11beff MH	105	size_t save_num_header_bytes_at_front =
cc11beff MH	106	crypt_stat->num_header_bytes_at_front;
e77a56dd	107
cc11beff MH	108	crypt_stat->num_header_bytes_at_front =
cc11beff MH	109	ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
e77a56dd	110	ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
cc11beff MH	111	crypt_stat->num_header_bytes_at_front =
cc11beff MH	112	save_num_header_bytes_at_front;
e77a56dd	113	}
237fead6	114
bf12be1c MH	115	/**
	116	* ecryptfs_copy_up_encrypted_with_header
	117	* @page: Sort of a ``virtual'' representation of the encrypted lower
	118	* file. The actual lower file does not have the metadata in
	119	* the header. This is locked.
	120	* @crypt_stat: The eCryptfs inode's cryptographic context
	121	*
	122	* The ``view'' is the version of the file that userspace winds up
	123	* seeing, with the header information inserted.
	124	*/
	125	static int
	126	ecryptfs_copy_up_encrypted_with_header(struct page *page,
	127	struct ecryptfs_crypt_stat *crypt_stat)
	128	{
	129	loff_t extent_num_in_page = 0;
	130	loff_t num_extents_per_page = (PAGE_CACHE_SIZE
	131	/ crypt_stat->extent_size);
	132	int rc = 0;
	133
	134	while (extent_num_in_page < num_extents_per_page) {
d6a13c17 MH	135	loff_t view_extent_num = ((((loff_t)page->index)
d6a13c17 MH	136	* num_extents_per_page)
bf12be1c	137	+ extent_num_in_page);
cc11beff MH	138	size_t num_header_extents_at_front =
	139	(crypt_stat->num_header_bytes_at_front
	140	/ crypt_stat->extent_size);
bf12be1c	141
cc11beff	142	if (view_extent_num < num_header_extents_at_front) {
bf12be1c MH	143	/* This is a header extent */
	144	char *page_virt;
	145
	146	page_virt = kmap_atomic(page, KM_USER0);
	147	memset(page_virt, 0, PAGE_CACHE_SIZE);
	148	/* TODO: Support more than one header extent */
	149	if (view_extent_num == 0) {
	150	rc = ecryptfs_read_xattr_region(
	151	page_virt, page->mapping->host);
	152	set_header_info(page_virt, crypt_stat);
	153	}
	154	kunmap_atomic(page_virt, KM_USER0);
	155	flush_dcache_page(page);
	156	if (rc) {
bf12be1c	157	printk(KERN_ERR "%s: Error reading xattr "
18d1dbf1	158	"region; rc = [%d]\n", __func__, rc);
bf12be1c MH	159	goto out;
bf12be1c MH	160	}
bf12be1c MH	161	} else {
	162	/* This is an encrypted data extent */
	163	loff_t lower_offset =
cc11beff MH	164	((view_extent_num * crypt_stat->extent_size)
cc11beff MH	165	- crypt_stat->num_header_bytes_at_front);
bf12be1c MH	166
	167	rc = ecryptfs_read_lower_page_segment(
	168	page, (lower_offset >> PAGE_CACHE_SHIFT),
	169	(lower_offset & ~PAGE_CACHE_MASK),
	170	crypt_stat->extent_size, page->mapping->host);
	171	if (rc) {
	172	printk(KERN_ERR "%s: Error attempting to read "
	173	"extent at offset [%lld] in the lower "
18d1dbf1	174	"file; rc = [%d]\n", __func__,
bf12be1c MH	175	lower_offset, rc);
	176	goto out;
	177	}
	178	}
	179	extent_num_in_page++;
	180	}
	181	out:
	182	return rc;
	183	}
	184
237fead6 MH	185	/**
237fead6 MH	186	* ecryptfs_readpage
bf12be1c MH	187	* @file: An eCryptfs file
bf12be1c MH	188	* @page: Page from eCryptfs inode mapping into which to stick the read data
237fead6 MH	189	*
	190	* Read in a page, decrypting if necessary.
	191	*
	192	* Returns zero on success; non-zero on error.
	193	*/
	194	static int ecryptfs_readpage(struct file file, struct page page)
	195	{
bf12be1c MH	196	struct ecryptfs_crypt_stat *crypt_stat =
bf12be1c MH	197	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6	198	int rc = 0;
237fead6	199
237fead6	200	if (!crypt_stat
e2bd99ec MH	201	\|\| !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
e2bd99ec MH	202	\|\| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
237fead6 MH	203	ecryptfs_printk(KERN_DEBUG,
237fead6 MH	204	"Passing through unencrypted page\n");
bf12be1c MH	205	rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
	206	PAGE_CACHE_SIZE,
	207	page->mapping->host);
e77a56dd MH	208	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
e77a56dd MH	209	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
bf12be1c MH	210	rc = ecryptfs_copy_up_encrypted_with_header(page,
	211	crypt_stat);
	212	if (rc) {
	213	printk(KERN_ERR "%s: Error attempting to copy "
	214	"the encrypted content from the lower "
	215	"file whilst inserting the metadata "
	216	"from the xattr into the header; rc = "
18d1dbf1	217	"[%d]\n", __func__, rc);
bf12be1c	218	goto out;
e77a56dd	219	}
bf12be1c	220
e77a56dd	221	} else {
bf12be1c MH	222	rc = ecryptfs_read_lower_page_segment(
	223	page, page->index, 0, PAGE_CACHE_SIZE,
	224	page->mapping->host);
e77a56dd MH	225	if (rc) {
	226	printk(KERN_ERR "Error reading page; rc = "
	227	"[%d]\n", rc);
	228	goto out;
	229	}
	230	}
237fead6	231	} else {
0216f7f7	232	rc = ecryptfs_decrypt_page(page);
237fead6	233	if (rc) {
237fead6 MH	234	ecryptfs_printk(KERN_ERR, "Error decrypting page; "
	235	"rc = [%d]\n", rc);
	236	goto out;
	237	}
	238	}
237fead6	239	out:
16a72c45 MH	240	if (rc)
	241	ClearPageUptodate(page);
	242	else
	243	SetPageUptodate(page);
237fead6 MH	244	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
	245	page->index);
	246	unlock_page(page);
	247	return rc;
	248	}
	249
dd2a3b7a MH	250	/**
	251	* Called with lower inode mutex held.
	252	*/
237fead6 MH	253	static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
	254	{
	255	struct inode *inode = page->mapping->host;
	256	int end_byte_in_page;
237fead6	257
9d8b8ce5 MH	258	if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
	259	goto out;
	260	end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
	261	if (to > end_byte_in_page)
	262	end_byte_in_page = to;
eebd2aa3	263	zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
237fead6	264	out:
9d8b8ce5	265	return 0;
237fead6 MH	266	}
237fead6 MH	267
e4465fda	268	/**
807b7ebe	269	* ecryptfs_write_begin
e4465fda	270	* @file: The eCryptfs file
807b7ebe BP	271	* @mapping: The eCryptfs object
	272	* @pos: The file offset at which to start writing
	273	* @len: Length of the write
	274	* @flags: Various flags
	275	* @pagep: Pointer to return the page
	276	* @fsdata: Pointer to return fs data (unused)
e4465fda MH	277	*
	278	* This function must zero any hole we create
	279	*
	280	* Returns zero on success; non-zero otherwise
	281	*/
807b7ebe BP	282	static int ecryptfs_write_begin(struct file *file,
	283	struct address_space *mapping,
	284	loff_t pos, unsigned len, unsigned flags,
	285	struct page pagep, void fsdata)
237fead6	286	{
807b7ebe BP	287	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
807b7ebe BP	288	struct page *page;
7a3f595c	289	loff_t prev_page_end_size;
e4465fda	290	int rc = 0;
237fead6	291
54566b2c	292	page = grab_cache_page_write_begin(mapping, index, flags);
807b7ebe BP	293	if (!page)
	294	return -ENOMEM;
	295	*pagep = page;
	296
16a72c45	297	if (!PageUptodate(page)) {
e4465fda MH	298	struct ecryptfs_crypt_stat *crypt_stat =
	299	&ecryptfs_inode_to_private(
	300	file->f_path.dentry->d_inode)->crypt_stat;
	301
	302	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
	303	\|\| (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
	304	rc = ecryptfs_read_lower_page_segment(
807b7ebe	305	page, index, 0, PAGE_CACHE_SIZE, mapping->host);
e4465fda MH	306	if (rc) {
	307	printk(KERN_ERR "%s: Error attemping to read "
	308	"lower page segment; rc = [%d]\n",
18d1dbf1	309	__func__, rc);
e4465fda MH	310	ClearPageUptodate(page);
	311	goto out;
	312	} else
	313	SetPageUptodate(page);
	314	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
	315	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
	316	rc = ecryptfs_copy_up_encrypted_with_header(
	317	page, crypt_stat);
	318	if (rc) {
	319	printk(KERN_ERR "%s: Error attempting "
	320	"to copy the encrypted content "
	321	"from the lower file whilst "
	322	"inserting the metadata from "
	323	"the xattr into the header; rc "
18d1dbf1	324	"= [%d]\n", __func__, rc);
e4465fda MH	325	ClearPageUptodate(page);
	326	goto out;
	327	}
	328	SetPageUptodate(page);
	329	} else {
	330	rc = ecryptfs_read_lower_page_segment(
807b7ebe BP	331	page, index, 0, PAGE_CACHE_SIZE,
807b7ebe BP	332	mapping->host);
e4465fda MH	333	if (rc) {
	334	printk(KERN_ERR "%s: Error reading "
	335	"page; rc = [%d]\n",
18d1dbf1	336	__func__, rc);
e4465fda MH	337	ClearPageUptodate(page);
	338	goto out;
	339	}
	340	SetPageUptodate(page);
	341	}
	342	} else {
	343	rc = ecryptfs_decrypt_page(page);
	344	if (rc) {
	345	printk(KERN_ERR "%s: Error decrypting page "
	346	"at index [%ld]; rc = [%d]\n",
18d1dbf1	347	__func__, page->index, rc);
e4465fda MH	348	ClearPageUptodate(page);
	349	goto out;
	350	}
16a72c45	351	SetPageUptodate(page);
e4465fda	352	}
16a72c45	353	}
807b7ebe	354	prev_page_end_size = ((loff_t)index << PAGE_CACHE_SHIFT);
e4465fda MH	355	/* If creating a page or more of holes, zero them out via truncate.
e4465fda MH	356	* Note, this will increase i_size. */
807b7ebe	357	if (index != 0) {
7a3f595c	358	if (prev_page_end_size > i_size_read(page->mapping->host)) {
240e2df5	359	rc = ecryptfs_truncate(file->f_path.dentry,
7a3f595c	360	prev_page_end_size);
240e2df5	361	if (rc) {
e4465fda	362	printk(KERN_ERR "%s: Error on attempt to "
240e2df5	363	"truncate to (higher) offset [%lld];"
18d1dbf1	364	" rc = [%d]\n", __func__,
e4465fda	365	prev_page_end_size, rc);
240e2df5 MH	366	goto out;
240e2df5 MH	367	}
53a2731f	368	}
7a3f595c	369	}
e4465fda MH	370	/* Writing to a new page, and creating a small hole from start
e4465fda MH	371	* of page? Zero it out. */
807b7ebe BP	372	if ((i_size_read(mapping->host) == prev_page_end_size)
807b7ebe BP	373	&& (pos != 0))
eebd2aa3	374	zero_user(page, 0, PAGE_CACHE_SIZE);
237fead6 MH	375	out:
	376	return rc;
	377	}
	378
237fead6 MH	379	/**
	380	* ecryptfs_write_inode_size_to_header
	381	*
	382	* Writes the lower file size to the first 8 bytes of the header.
	383	*
	384	* Returns zero on success; non-zero on error.
	385	*/
0216f7f7	386	static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
237fead6	387	{
0216f7f7 MH	388	char *file_size_virt;
0216f7f7 MH	389	int rc;
237fead6	390
0216f7f7 MH	391	file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
	392	if (!file_size_virt) {
	393	rc = -ENOMEM;
ae73fc09 MH	394	goto out;
ae73fc09 MH	395	}
0a688ad7	396	put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
0216f7f7 MH	397	rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
	398	sizeof(u64));
	399	kfree(file_size_virt);
96a7b9c2	400	if (rc < 0)
0216f7f7	401	printk(KERN_ERR "%s: Error writing file size to header; "
18d1dbf1	402	"rc = [%d]\n", __func__, rc);
96a7b9c2 TH	403	else
96a7b9c2 TH	404	rc = 0;
237fead6 MH	405	out:
	406	return rc;
	407	}
	408
0216f7f7 MH	409	struct kmem_cache *ecryptfs_xattr_cache;
	410
	411	static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
dd2a3b7a MH	412	{
	413	ssize_t size;
	414	void *xattr_virt;
0216f7f7 MH	415	struct dentry *lower_dentry =
	416	ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
	417	struct inode *lower_inode = lower_dentry->d_inode;
dd2a3b7a MH	418	int rc;
dd2a3b7a MH	419
0216f7f7 MH	420	if (!lower_inode->i_op->getxattr \|\| !lower_inode->i_op->setxattr) {
	421	printk(KERN_WARNING
	422	"No support for setting xattr in lower filesystem\n");
	423	rc = -ENOSYS;
	424	goto out;
	425	}
dd2a3b7a MH	426	xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
	427	if (!xattr_virt) {
	428	printk(KERN_ERR "Out of memory whilst attempting to write "
	429	"inode size to xattr\n");
	430	rc = -ENOMEM;
	431	goto out;
	432	}
0216f7f7 MH	433	mutex_lock(&lower_inode->i_mutex);
	434	size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	435	xattr_virt, PAGE_CACHE_SIZE);
dd2a3b7a MH	436	if (size < 0)
dd2a3b7a MH	437	size = 8;
0a688ad7	438	put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
0216f7f7 MH	439	rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
	440	xattr_virt, size, 0);
	441	mutex_unlock(&lower_inode->i_mutex);
dd2a3b7a MH	442	if (rc)
	443	printk(KERN_ERR "Error whilst attempting to write inode size "
	444	"to lower file xattr; rc = [%d]\n", rc);
	445	kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
	446	out:
	447	return rc;
	448	}
	449
0216f7f7	450	int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
dd2a3b7a MH	451	{
	452	struct ecryptfs_crypt_stat *crypt_stat;
	453
0216f7f7	454	crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
13a791b4	455	BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
dd2a3b7a	456	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
0216f7f7	457	return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
dd2a3b7a	458	else
0216f7f7	459	return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
dd2a3b7a MH	460	}
dd2a3b7a MH	461
237fead6	462	/**
807b7ebe	463	* ecryptfs_write_end
237fead6	464	* @file: The eCryptfs file object
807b7ebe BP	465	* @mapping: The eCryptfs object
	466	* @pos: The file position
	467	* @len: The length of the data (unused)
	468	* @copied: The amount of data copied
237fead6	469	* @page: The eCryptfs page
807b7ebe	470	* @fsdata: The fsdata (unused)
237fead6 MH	471	*
	472	* This is where we encrypt the data and pass the encrypted data to
	473	* the lower filesystem. In OpenPGP-compatible mode, we operate on
	474	* entire underlying packets.
	475	*/
807b7ebe BP	476	static int ecryptfs_write_end(struct file *file,
	477	struct address_space *mapping,
	478	loff_t pos, unsigned len, unsigned copied,
	479	struct page page, void fsdata)
237fead6	480	{
807b7ebe BP	481	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	482	unsigned from = pos & (PAGE_CACHE_SIZE - 1);
	483	unsigned to = from + copied;
	484	struct inode *ecryptfs_inode = mapping->host;
bf12be1c MH	485	struct ecryptfs_crypt_stat *crypt_stat =
bf12be1c MH	486	&ecryptfs_inode_to_private(file->f_path.dentry->d_inode)->crypt_stat;
237fead6 MH	487	int rc;
237fead6 MH	488
e2bd99ec	489	if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
237fead6 MH	490	ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
237fead6 MH	491	"crypt_stat at memory location [%p]\n", crypt_stat);
e2bd99ec	492	crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
237fead6 MH	493	} else
	494	ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
	495	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
807b7ebe	496	"(page w/ index = [0x%.16x], to = [%d])\n", index, to);
13a791b4 TH	497	if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
	498	rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0,
	499	to);
	500	if (!rc) {
	501	rc = copied;
	502	fsstack_copy_inode_size(ecryptfs_inode,
	503	ecryptfs_inode_to_lower(ecryptfs_inode));
	504	}
	505	goto out;
	506	}
bf12be1c	507	/* Fills in zeros if 'to' goes beyond inode size */
237fead6 MH	508	rc = fill_zeros_to_end_of_page(page, to);
	509	if (rc) {
	510	ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
807b7ebe	511	"zeros in page with index = [0x%.16x]\n", index);
237fead6 MH	512	goto out;
237fead6 MH	513	}
0216f7f7	514	rc = ecryptfs_encrypt_page(page);
237fead6 MH	515	if (rc) {
237fead6 MH	516	ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
807b7ebe	517	"index [0x%.16x])\n", index);
237fead6 MH	518	goto out;
237fead6 MH	519	}
807b7ebe BP	520	if (pos + copied > i_size_read(ecryptfs_inode)) {
807b7ebe BP	521	i_size_write(ecryptfs_inode, pos + copied);
237fead6	522	ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
bf12be1c	523	"[0x%.16x]\n", i_size_read(ecryptfs_inode));
237fead6	524	}
bf12be1c	525	rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
dd2a3b7a MH	526	if (rc)
	527	printk(KERN_ERR "Error writing inode size to metadata; "
	528	"rc = [%d]\n", rc);
807b7ebe BP	529	else
807b7ebe BP	530	rc = copied;
237fead6	531	out:
807b7ebe BP	532	unlock_page(page);
807b7ebe BP	533	page_cache_release(page);
237fead6 MH	534	return rc;
	535	}
	536
237fead6 MH	537	static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
	538	{
	539	int rc = 0;
	540	struct inode *inode;
	541	struct inode *lower_inode;
	542
	543	inode = (struct inode *)mapping->host;
	544	lower_inode = ecryptfs_inode_to_lower(inode);
	545	if (lower_inode->i_mapping->a_ops->bmap)
	546	rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
	547	block);
	548	return rc;
	549	}
	550
7f09410b	551	const struct address_space_operations ecryptfs_aops = {
237fead6 MH	552	.writepage = ecryptfs_writepage,
237fead6 MH	553	.readpage = ecryptfs_readpage,
807b7ebe BP	554	.write_begin = ecryptfs_write_begin,
807b7ebe BP	555	.write_end = ecryptfs_write_end,
237fead6	556	.bmap = ecryptfs_bmap,
237fead6	557	};