1 files changed, 359 insertions, 0 deletions
diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
new file mode 100644
index 00000000000..e59c94add12
--- /dev/null
+++ b/fs/ecryptfs/read_write.c
@@ -0,0 +1,359 @@
+/**
+ * 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;
+}