1 files changed, 561 insertions, 0 deletions

diff --git a/fs/ecryptfs/mmap.c b/fs/ecryptfs/mmap.c
new file mode 100644
index 000000000..cf2085229
--- /dev/null
+++ b/fs/ecryptfs/mmap.c
@@ -0,0 +1,561 @@
+/**
+ * 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 inode *inode, loff_t index)
+{
+	struct page *page = read_mapping_page(inode->i_mapping, index, NULL);
+	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
+ *
+ * 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_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%.16lx])\n", page->index);
+		ClearPageUptodate(page);
+		goto out;
+	}
+	SetPageUptodate(page);
+out:
+	unlock_page(page);
+	return rc;
+}
+
+static void strip_xattr_flag(char *page_virt,
+			     struct ecryptfs_crypt_stat *crypt_stat)
+{
+	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
+		size_t written;
+
+		crypt_stat->flags &= ~ECRYPTFS_METADATA_IN_XATTR;
+		ecryptfs_write_crypt_stat_flags(page_virt, crypt_stat,
+						&written);
+		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
+	}
+}
+
+/**
+ *   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
+ */
+
+/**
+ * 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->metadata_size / 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);
+			memset(page_virt, 0, PAGE_CACHE_SIZE);
+			/* TODO: Support more than one header extent */
+			if (view_extent_num == 0) {
+				size_t written;
+
+				rc = ecryptfs_read_xattr_region(
+					page_virt, page->mapping->host);
+				strip_xattr_flag(page_virt + 16, crypt_stat);
+				ecryptfs_write_header_metadata(page_virt + 20,
+							       crypt_stat,
+							       &written);
+			}
+			kunmap_atomic(page_virt);
+			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->metadata_size);
+
+			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(page->mapping->host)->crypt_stat;
+	int rc = 0;
+
+	if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
+		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%.16lx]\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;
+
+	prev_page_end_size = ((loff_t)index << PAGE_CACHE_SHIFT);
+	if (!PageUptodate(page)) {
+		struct ecryptfs_crypt_stat *crypt_stat =
+			&ecryptfs_inode_to_private(mapping->host)->crypt_stat;
+
+		if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
+			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 {
+			if (prev_page_end_size
+			    >= i_size_read(page->mapping->host)) {
+				zero_user(page, 0, PAGE_CACHE_SIZE);
+				SetPageUptodate(page);
+			} else if (len < PAGE_CACHE_SIZE) {
+				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);
+			}
+		}
+	}
+	/* 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:
+	if (unlikely(rc)) {
+		unlock_page(page);
+		page_cache_release(page);
+		*pagep = NULL;
+	}
+	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_path.dentry;
+	struct inode *lower_inode = d_inode(lower_dentry);
+	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)
+ */
+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(ecryptfs_inode)->crypt_stat;
+	int rc;
+
+	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
+			"(page w/ index = [0x%.16lx], 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;
+	}
+	if (!PageUptodate(page)) {
+		if (copied < PAGE_CACHE_SIZE) {
+			rc = 0;
+			goto out;
+		}
+		SetPageUptodate(page);
+	}
+	/* 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%.16lx]\n", index);
+		goto out;
+	}
+	rc = ecryptfs_encrypt_page(page);
+	if (rc) {
+		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
+				"index [0x%.16lx])\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%.16llx]\n",
+			(unsigned long long)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,
+};