eCryptfs: read_write.c routines (da0102a1) · Commits · 戴 / test

fs/ecryptfs/Makefile

+1 −1

Original line number	Diff line number	Diff line
		@@ -4,4 +4,4 @@

		obj-$(CONFIG_ECRYPT_FS) += ecryptfs.o

		ecryptfs-objs := dentry.o file.o inode.o main.o super.o mmap.o crypto.o keystore.o messaging.o netlink.o debug.o
		ecryptfs-objs := dentry.o file.o inode.o main.o super.o mmap.o read_write.o crypto.o keystore.o messaging.o netlink.o debug.o

fs/ecryptfs/ecryptfs_kernel.h

+18 −0

Original line number	Diff line number	Diff line
		@@ -260,6 +260,8 @@ struct ecryptfs_crypt_stat {
		struct ecryptfs_inode_info {
		struct inode vfs_inode;
		struct inode *wii_inode;
		struct file *lower_file;
		struct mutex lower_file_mutex;
		struct ecryptfs_crypt_stat crypt_stat;
		};

		@@ -653,5 +655,21 @@ int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
		char *sig);
		int ecryptfs_write_zeros(struct file *file, pgoff_t index, int start,
		int num_zeros);
		int ecryptfs_write_lower(struct inode ecryptfs_inode, char data,
		loff_t offset, size_t size);
		int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
		struct page *page_for_lower,
		size_t offset_in_page, size_t size);
		int ecryptfs_write(struct file ecryptfs_file, char data, loff_t offset,
		size_t size);
		int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
		struct inode *ecryptfs_inode);
		int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
		pgoff_t page_index,
		size_t offset_in_page, size_t size,
		struct inode *ecryptfs_inode);
		int ecryptfs_read(char *data, loff_t offset, size_t size,
		struct file *ecryptfs_file);
		struct page ecryptfs_get1page(struct file file, loff_t index);

		#endif /* #ifndef ECRYPTFS_KERNEL_H */

fs/ecryptfs/mmap.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -44,7 +44,7 @@ struct kmem_cache *ecryptfs_lower_page_cache;
		* Returns unlocked and up-to-date page (if ok), with increased
		* refcnt.
		*/
		static struct page ecryptfs_get1page(struct file file, int index)
		struct page ecryptfs_get1page(struct file file, loff_t index)
		{
		struct dentry *dentry;
		struct inode *inode;

fs/ecryptfs/read_write.c

0 → 100644

+359 −0

Original line number	Diff line number	Diff line
		/**
		* eCryptfs: Linux filesystem encryption layer
		*
		* Copyright (C) 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/fs.h>
		#include <linux/pagemap.h>
		#include "ecryptfs_kernel.h"

		/**
		* ecryptfs_write_lower
		* @ecryptfs_inode: The eCryptfs inode
		* @data: Data to write
		* @offset: Byte offset in the lower file to which to write the data
		* @size: Number of bytes from @data to write at @offset in the lower
		* file
		*
		* Write data to the lower file.
		*
		* Returns zero on success; non-zero on error
		*/
		int ecryptfs_write_lower(struct inode ecryptfs_inode, char data,
		loff_t offset, size_t size)
		{
		struct ecryptfs_inode_info *inode_info;
		ssize_t octets_written;
		mm_segment_t fs_save;
		int rc = 0;

		inode_info = ecryptfs_inode_to_private(ecryptfs_inode);
		mutex_lock(&inode_info->lower_file_mutex);
		BUG_ON(!inode_info->lower_file);
		inode_info->lower_file->f_pos = offset;
		fs_save = get_fs();
		set_fs(get_ds());
		octets_written = vfs_write(inode_info->lower_file, data, size,
		&inode_info->lower_file->f_pos);
		set_fs(fs_save);
		if (octets_written < 0) {
		printk(KERN_ERR "%s: octets_written = [%td]; "
		"expected [%td]\n", __FUNCTION__, octets_written, size);
		rc = -EINVAL;
		}
		mutex_unlock(&inode_info->lower_file_mutex);
		mark_inode_dirty_sync(ecryptfs_inode);
		return rc;
		}

		/**
		* ecryptfs_write_lower_page_segment
		* @ecryptfs_inode: The eCryptfs inode
		* @page_for_lower: The page containing the data to be written to the
		* lower file
		* @offset_in_page: The offset in the @page_for_lower from which to
		* start writing the data
		* @size: The amount of data from @page_for_lower to write to the
		* lower file
		*
		* Determines the byte offset in the file for the given page and
		* offset within the page, maps the page, and makes the call to write
		* the contents of @page_for_lower to the lower inode.
		*
		* Returns zero on success; non-zero otherwise
		*/
		int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode,
		struct page *page_for_lower,
		size_t offset_in_page, size_t size)
		{
		char *virt;
		loff_t offset;
		int rc;

		offset = (page_for_lower->index << PAGE_CACHE_SHIFT) + offset_in_page;
		virt = kmap(page_for_lower);
		rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);
		kunmap(page_for_lower);
		return rc;
		}

		/**
		* ecryptfs_write
		* @ecryptfs_file: The eCryptfs file into which to write
		* @data: Virtual address where data to write is located
		* @offset: Offset in the eCryptfs file at which to begin writing the
		* data from @data
		* @size: The number of bytes to write from @data
		*
		* Write an arbitrary amount of data to an arbitrary location in the
		* eCryptfs inode page cache. This is done on a page-by-page, and then
		* by an extent-by-extent, basis; individual extents are encrypted and
		* written to the lower page cache (via VFS writes). This function
		* takes care of all the address translation to locations in the lower
		* filesystem; it also handles truncate events, writing out zeros
		* where necessary.
		*
		* Returns zero on success; non-zero otherwise
		*/
		int ecryptfs_write(struct file ecryptfs_file, char data, loff_t offset,
		size_t size)
		{
		struct page *ecryptfs_page;
		char *ecryptfs_page_virt;
		u64 ecryptfs_file_size = i_size_read(ecryptfs_file->f_dentry->d_inode);
		loff_t data_offset = 0;
		loff_t pos;
		int rc = 0;

		if (offset > ecryptfs_file_size)
		pos = ecryptfs_file_size;
		else
		pos = offset;
		while (pos < (offset + size)) {
		pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
		size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
		size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
		size_t total_remaining_bytes = ((offset + size) - pos);

		if (num_bytes > total_remaining_bytes)
		num_bytes = total_remaining_bytes;
		if (pos < offset) {
		size_t total_remaining_zeros = (offset - pos);

		if (num_bytes > total_remaining_zeros)
		num_bytes = total_remaining_zeros;
		}
		ecryptfs_page = ecryptfs_get1page(ecryptfs_file,
		ecryptfs_page_idx);
		if (IS_ERR(ecryptfs_page)) {
		rc = PTR_ERR(ecryptfs_page);
		printk(KERN_ERR "%s: Error getting page at "
		"index [%ld] from eCryptfs inode "
		"mapping; rc = [%d]\n", __FUNCTION__,
		ecryptfs_page_idx, rc);
		goto out;
		}
		if (start_offset_in_page) {
		/* Read in the page from the lower
		* into the eCryptfs inode page cache,
		* decrypting */
		if ((rc = ecryptfs_decrypt_page(NULL, /* placeholder for git-bisect */
		ecryptfs_page))) {
		printk(KERN_ERR "%s: Error decrypting "
		"page; rc = [%d]\n",
		__FUNCTION__, rc);
		page_cache_release(ecryptfs_page);
		goto out;
		}
		}
		ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
		if (pos >= offset) {
		memcpy(((char *)ecryptfs_page_virt
		+ start_offset_in_page),
		(data + data_offset), num_bytes);
		data_offset += num_bytes;
		} else {
		/* We are extending past the previous end of the file.
		* Fill in zero values up to the start of where we
		* will be writing data. */
		memset(((char *)ecryptfs_page_virt
		+ start_offset_in_page), 0, num_bytes);
		}
		kunmap_atomic(ecryptfs_page_virt, KM_USER0);
		flush_dcache_page(ecryptfs_page);
		rc = ecryptfs_encrypt_page(NULL /* placeholder for git-bisect */);
		if (rc) {
		printk(KERN_ERR "%s: Error encrypting "
		"page; rc = [%d]\n", __FUNCTION__, rc);
		page_cache_release(ecryptfs_page);
		goto out;
		}
		page_cache_release(ecryptfs_page);
		pos += num_bytes;
		}
		if ((offset + size) > ecryptfs_file_size) {
		i_size_write(ecryptfs_file->f_dentry->d_inode, (offset + size));
		rc = ecryptfs_write_inode_size_to_metadata(NULL, NULL, NULL,
		NULL, 0); /* placeholders for git-bisect */
		if (rc) {
		printk(KERN_ERR "Problem with "
		"ecryptfs_write_inode_size_to_metadata; "
		"rc = [%d]\n", rc);
		goto out;
		}
		}
		out:
		return rc;
		}

		/**
		* ecryptfs_read_lower
		* @data: The read data is stored here by this function
		* @offset: Byte offset in the lower file from which to read the data
		* @size: Number of bytes to read from @offset of the lower file and
		* store into @data
		* @ecryptfs_inode: The eCryptfs inode
		*
		* Read @size bytes of data at byte offset @offset from the lower
		* inode into memory location @data.
		*
		* Returns zero on success; non-zero on error
		*/
		int ecryptfs_read_lower(char *data, loff_t offset, size_t size,
		struct inode *ecryptfs_inode)
		{
		struct ecryptfs_inode_info *inode_info =
		ecryptfs_inode_to_private(ecryptfs_inode);
		ssize_t octets_read;
		mm_segment_t fs_save;
		size_t i;
		int rc = 0;

		mutex_lock(&inode_info->lower_file_mutex);
		BUG_ON(!inode_info->lower_file);
		inode_info->lower_file->f_pos = offset;
		fs_save = get_fs();
		set_fs(get_ds());
		octets_read = vfs_read(inode_info->lower_file, data, size,
		&inode_info->lower_file->f_pos);
		set_fs(fs_save);
		if (octets_read < 0) {
		printk(KERN_ERR "%s: octets_read = [%td]; "
		"expected [%td]\n", __FUNCTION__, octets_read, size);
		rc = -EINVAL;
		}
		mutex_unlock(&inode_info->lower_file_mutex);
		for (i = 0; i < size; i += PAGE_CACHE_SIZE) {
		struct page *data_page;

		data_page = virt_to_page(data + i);
		flush_dcache_page(data_page);
		if (rc)
		ClearPageUptodate(data_page);
		else
		SetPageUptodate(data_page);
		}
		return rc;
		}

		/**
		* ecryptfs_read_lower_page_segment
		* @page_for_ecryptfs: The page into which data for eCryptfs will be
		* written
		* @offset_in_page: Offset in @page_for_ecryptfs from which to start
		* writing
		* @size: The number of bytes to write into @page_for_ecryptfs
		* @ecryptfs_inode: The eCryptfs inode
		*
		* Determines the byte offset in the file for the given page and
		* offset within the page, maps the page, and makes the call to read
		* the contents of @page_for_ecryptfs from the lower inode.
		*
		* Returns zero on success; non-zero otherwise
		*/
		int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs,
		pgoff_t page_index,
		size_t offset_in_page, size_t size,
		struct inode *ecryptfs_inode)
		{
		char *virt;
		loff_t offset;
		int rc;

		offset = ((page_index << PAGE_CACHE_SHIFT) + offset_in_page);
		virt = kmap(page_for_ecryptfs);
		rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode);
		kunmap(page_for_ecryptfs);
		return rc;
		}

		/**
		* ecryptfs_read
		* @data: The virtual address into which to write the data read (and
		* possibly decrypted) from the lower file
		* @offset: The offset in the decrypted view of the file from which to
		* read into @data
		* @size: The number of bytes to read into @data
		* @ecryptfs_file: The eCryptfs file from which to read
		*
		* Read an arbitrary amount of data from an arbitrary location in the
		* eCryptfs page cache. This is done on an extent-by-extent basis;
		* individual extents are decrypted and read from the lower page
		* cache (via VFS reads). This function takes care of all the
		* address translation to locations in the lower filesystem.
		*
		* Returns zero on success; non-zero otherwise
		*/
		int ecryptfs_read(char *data, loff_t offset, size_t size,
		struct file *ecryptfs_file)
		{
		struct page *ecryptfs_page;
		char *ecryptfs_page_virt;
		u64 ecryptfs_file_size = i_size_read(ecryptfs_file->f_dentry->d_inode);
		loff_t data_offset = 0;
		loff_t pos;
		int rc = 0;

		if ((offset + size) > ecryptfs_file_size) {
		rc = -EINVAL;
		printk(KERN_ERR "%s: Attempt to read data past the end of the "
		"file; offset = [%lld]; size = [%td]; "
		"ecryptfs_file_size = [%lld]\n",
		__FUNCTION__, offset, size, ecryptfs_file_size);
		goto out;
		}
		pos = offset;
		while (pos < (offset + size)) {
		pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT);
		size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK);
		size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page);
		size_t total_remaining_bytes = ((offset + size) - pos);

		if (num_bytes > total_remaining_bytes)
		num_bytes = total_remaining_bytes;
		ecryptfs_page = ecryptfs_get1page(ecryptfs_file,
		ecryptfs_page_idx);
		if (IS_ERR(ecryptfs_page)) {
		rc = PTR_ERR(ecryptfs_page);
		printk(KERN_ERR "%s: Error getting page at "
		"index [%ld] from eCryptfs inode "
		"mapping; rc = [%d]\n", __FUNCTION__,
		ecryptfs_page_idx, rc);
		goto out;
		}
		rc = ecryptfs_decrypt_page(NULL /* placeholder for git-bisect */, ecryptfs_page);
		if (rc) {
		printk(KERN_ERR "%s: Error decrypting "
		"page; rc = [%d]\n", __FUNCTION__, rc);
		page_cache_release(ecryptfs_page);
		goto out;
		}
		ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
		memcpy((data + data_offset),
		((char *)ecryptfs_page_virt + start_offset_in_page),
		num_bytes);
		kunmap_atomic(ecryptfs_page_virt, KM_USER0);
		page_cache_release(ecryptfs_page);
		pos += num_bytes;
		data_offset += num_bytes;
		}
		out:
		return rc;
		}

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