[PATCH 10/12: eCryptfs] Mmap operations

Phillip Hellewell
2005-11-03T03:55:12Z

eCryptfs mmap operations. The bulk encryption and decryption takes
place here.

We are aware of one possibility of data inconsistency in the current
scheme (when an IV is written and the associated page is not). We have
a patch currently being tested that avoids this problem by deriving
the initialization vector from a root IV combined with the page
index. Another patch in plan is to go to three writes -- one to write
all 0's to the IV, then to write the page data, then to write the IV;
a failure after any of these writes will be detectable in that case.

Signed off by: Phillip Hellewell <phillip@hellewell.homeip.net>
Signed off by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed off by: Michael Thompson <mmcthomps@us.ibm.com>
Signed off by: Kent Yoder <yoder1@us.ibm.com>

mmap.c | 1045 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 1045 insertions(+)
--- linux-2.6.14-rc5-mm1/fs/ecryptfs/mmap.c 1969-12-31 18:00:00.000000000 -0600
+++ linux-2.6.14-rc5-mm1-ecryptfs/fs/ecryptfs/mmap.c 2005-11-01 14:40:17.000000000 -0600
@@ -0,0 +1,1045 @@
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ * This is where eCryptfs handles the bulk encryption and decryption,
+ * with upper-lower file index interpolations.
+ *
+ * Copyright (c) 1997-2003 Erez Zadok
+ * Copyright (c) 2001-2003 Stony Brook University
+ * Copyright (c) 2005 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.
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif /* HAVE_CONFIG_H */
+#include <linux/pagemap.h>
+#include <linux/writeback.h>
+#include <linux/page-flags.h>
+#include <linux/crypto.h>
+#include <asm/scatterlist.h>
+#include "ecryptfs_kernel.h"
+
+static int ecryptfs_commit_write(struct file *file, struct page *page,
+ unsigned from, unsigned to);
+static int ecryptfs_prepare_write(struct file *file, struct page *page,
+ unsigned from, unsigned to);
+
+kmem_cache_t *ecryptfs_lower_page_cache;
+
+/**
+ * Get one page from cache or lower f/s, return error otherwise.
+ *
+ * @return Unlocked and up-to-date page (if ok), with increased
+ * refcnt.
+ */
+static struct page *ecryptfs_get1page(struct file *file, int index)
+{
+ struct page *page;
+ struct dentry *dentry;
+ struct inode *inode;
+ struct address_space *mapping;
+ int rc;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
+ dentry = file->f_dentry;
+ inode = dentry->d_inode;
+ mapping = inode->i_mapping;
+ if (index < 0) {
+ ecryptfs_printk(1, KERN_ERR, "BUG: index=%d\n", index);
+ page = ERR_PTR(-EIO);
+ goto out;
+ }
+ page = read_cache_page(mapping, index,
+ (filler_t *) mapping->a_ops->readpage,
+ (void *)file);
+ if (IS_ERR(page))
+ goto out;
+ wait_on_page_locked(page);
+ if (!PageUptodate(page)) {
+ lock_page(page);
+ rc = mapping->a_ops->readpage(file, page);
+ if (rc) {
+ page = ERR_PTR(rc);
+ goto out;
+ }
+ wait_on_page_locked(page);
+ if (!PageUptodate(page)) {
+ page = ERR_PTR(-EIO);
+ goto out;
+ }
+ }
+out:
+ ecryptfs_printk(1, KERN_NOTICE, "Exit\n");
+ return page;
+}
+
+/**
+ * Write a specified number of zero's to a page.
+ *
+ * N.B. (start + num_zeros) _must_ be less than or equal to PAGE_CACHE_SIZE
+ *
+ * @param file The ecryptfs file
+ * @param index The index in which we are writing
+ * @param start The position after the last block of data
+ * @param num_zeros The number of zeros to write
+ */
+static
+int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
+{
+ int rc = 0;
+ struct page *tmp_page;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter; index = [%lu], start offset = "
+ "[%d] num_zeros = [%d]\n", index, start, num_zeros);
+ tmp_page = ecryptfs_get1page(file, index);
+ if (IS_ERR(tmp_page)) {
+ ecryptfs_printk(0, KERN_ERR, "Error getting page at index "
+ "[%lu]\n", index);
+ rc = PTR_ERR(tmp_page);
+ goto out;
+ }
+ kmap(tmp_page);
+ memset(((char *)page_address(tmp_page) + start), 0, num_zeros);
+ rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error preparing to write zero's "
+ "to remainder of page at index [%lu]\n", index);
+ kunmap(tmp_page);
+ page_cache_release(tmp_page);
+ goto out;
+ }
+ rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
+ if (rc < 0) {
+ ecryptfs_printk(0, KERN_ERR, "Error attempting to write zero's "
+ "to remainder of page at index [%lu]\n", index);
+ kunmap(tmp_page);
+ page_cache_release(tmp_page);
+ goto out;
+ }
+ rc = 0;
+ kunmap(tmp_page);
+ page_cache_release(tmp_page);
+out:
+ ecryptfs_printk(1, KERN_NOTICE, "Exit\n");
+ return rc;
+}
+
+/**
+ * Function for handling creation of holes when lseek-ing past the end
+ * of the file and then writing some data.
+ *
+ * N.B.
+ * This function does NOT support shrinking, only growing a file.
+ * The code _will_ BUG() if this requirement is not met.
+ * The new_length _myust_ be greater than the current length.
+ *
+ * @param file The ecryptfs file
+ * @param new_length The new length of the data in the underlying file;
+ * everything between the prior end of the file and the new
+ * end of the file will be filled with zero's.
+ * N.B. new_length must be greater than current length
+ * @return Zero on success; non-zero otherwise
+ */
+int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
+{
+ int rc = 0;
+ struct dentry *dentry = file->f_dentry;
+ struct inode *inode = dentry->d_inode;
+ pgoff_t old_end_page_index = 0;
+ pgoff_t index = old_end_page_index;
+ int old_end_pos_in_page = -1;
+ pgoff_t new_end_page_index;
+ int new_end_pos_in_page;
+ loff_t cur_length = i_size_read(inode);
+
+ ecryptfs_printk(1, KERN_NOTICE, "Enter; inode->i_size = [%llu]; "
+ "new_length = [%llu]\n", cur_length, new_length);
+ /* Sanity check */
+ if (cur_length >= new_length) {
+ ecryptfs_printk(0, KERN_ERR, "Called with new_length less than "
+ "or equal to the current length, this is "
+ "against function restrictions!\n");
+ BUG();
+ }
+ /* N.B. Notes on index calculations
+ * It is important to note that the size of the file will always be 1
+ * greater than the last block of data's position added to the data's
+ * index shifted by the page cache size.
+ * size = index * PAGE_CACHE_SIZE + pos + 1
+ *
+ * Example, a file with 1 block of data in the 0th index at the 0th
+ * position will be a file of size 1. Likewise, a file of 100 blocks
+ * of data will have it's last block in the 99th position.
+ *
+ * Therefore, a file of size page with PAGE_CACHE_SIZE blocks of data
+ * will have its last block of data in the (PAGE_CACHE_SIZE-1)th
+ * position, in the 0th index. A file with (PAGE_CACHE_SIZE + 1) blocks
+ * of data will have its last block of data in the 0th position of the
+ * 1st index. This calculation can be shown as:
+ * position = (size - 1) & ~PAGE_CACHE_MASK
+ * index = (size - 1) >> PAGE_CACHE_SHIFT
+ *
+ * Example:
+ * PAGE_CACHE_SHIFT = 12
+ * PAGE_CACHE_SIZE = (1UL << PAGE_CACHE_SHIFT) [or 4096]
+ * PAGE_CACHE_MASK = (~(PAGE_CACHE_SIZE-1)) [or ~(4096-1)]
+ *
+ * A size of 4095 yields:
+ * position = (4095 - 1) & ~PAGE_CACHE_MASK => 4094
+ * index = (4095 - 1) >> 12 => 0
+ *
+ * A size of 4096 yields:
+ * position = (4096 - 1) & ~PAGE_CACHE_MASK => 4095
+ * index = (4096 - 1) >> 12 => 0
+ *
+ * A size of 4097 yields:
+ * position = (4097 - 1) & ~PAGE_CACHE_MASK => 0
+ * index = (4097 - 1) >> 12 => 1
+ *
+ * From these examples, you can see that the logic that a
+ * file's last block of data is at the (size - 1)th position
+ * follows.
+ *
+ * A 0-length file is by this logic, undefined if positions
+ * and indicies are required to be positive integers. However,
+ * this is intuative, as a 0-length file has no data which to
+ * give a position and index to. However, to make our
+ * calculations work, we will use the default value of -1 if
+ * the size is 0. The following will apply:
+ * old size = 0
+ * old position = -1
+ * old index = 0
+ * new size = 1
+ * new position = 0
+ * new index = 0
+ *
+ * write_zeros(file,0,(-1+1) => 0, ((size-1) - (-1)) => size)
+ *
+ * Therefore, if the current size of the file is 0, then
+ * setting our index and position to -1 will result in valid
+ * calculations for the new index and position for the new
+ * size.
+ */
+ if (cur_length != 0) {
+ index = old_end_page_index =
+ ((cur_length - 1) >> PAGE_CACHE_SHIFT);
+ old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
+ }
+ new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
+ new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
+
+ ecryptfs_printk(1, KERN_NOTICE, "old_end_page_index = [%lu]; "
+ "old_end_pos_in_page = [%d]; "
+ "new_end_page_index = [%lu]; "
+ "new_end_pos_in_page = [%d]\n",
+ old_end_page_index, old_end_pos_in_page,
+ new_end_page_index, new_end_pos_in_page);
+ if (old_end_page_index == new_end_page_index) {
+ /* Start and end are in the same page; we just need to
+ * set a portion of the existing page to zero's */
+ rc = write_zeros(file, index, (old_end_pos_in_page + 1),
+ (new_end_pos_in_page - old_end_pos_in_page));
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "write_zeros(file=[%p], "
+ "index=[%lu], old_end_pos_in_page=[d], "
+ "(PAGE_CACHE_SIZE - new_end_pos_in_page"
+ "=[%d]"
+ ")=[d]) returned [%d]\n", file, index,
+ old_end_pos_in_page,
+ new_end_pos_in_page,
+ (PAGE_CACHE_SIZE - new_end_pos_in_page),
+ rc);
+ }
+ goto out;
+ }
+ /* Else, new position is outside of the current index.
+ * Fill remainder of current page with zeros.
+ * For each page after that page, will entire page with zeros.
+ * Upon reaching new last page, write as many zeros as required
+ * to fullfil the new size. */
+ /* Fill the remainder of the previous last page with zeros */
+ rc = write_zeros(file, index, (old_end_pos_in_page + 1),
+ ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "write_zeros(file=[%p], "
+ "index=[%lu], old_end_pos_in_page=[d], "
+ "(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
+ "returned [%d]\n", file, index,
+ old_end_pos_in_page,
+ (PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
+ goto out;
+ }
+ index++;
+ while (index < new_end_page_index) {
+ /* Fill all intermediate pages with zeros */
+ rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "write_zeros(file=[%p], "
+ "index=[%lu], old_end_pos_in_page=[d], "
+ "(PAGE_CACHE_SIZE - new_end_pos_in_page"
+ "=[%d]"
+ ")=[d]) returned [%d]\n", file, index,
+ old_end_pos_in_page,
+ new_end_pos_in_page,
+ (PAGE_CACHE_SIZE - new_end_pos_in_page),
+ rc);
+ goto out;
+ }
+ index++;
+ }
+ /* Fill the portion at the beginning of the last new page with
+ * zero's */
+ rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "write_zeros(file="
+ "[%p], index=[%lu], 0, "
+ "new_end_pos_in_page=[%d]"
+ "returned [%d]\n", file, index,
+ new_end_pos_in_page, rc);
+ goto out;
+ }
+out:
+ ecryptfs_printk((rc == 0 ? 1 : 0), KERN_NOTICE, "Exit; rc = [%d]\n",
+ rc);
+ return rc;
+}
+
+/**
+ * @param page Page that is locked before this call is made
+ */
+static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+ int err = -EIO;
+ unsigned long lower_index;
+ struct inode *inode;
+ struct inode *lower_inode;
+ struct page *lower_page;
+ char *kaddr, *lower_kaddr;
+ struct ecryptfs_crypt_stats *crypt_stats;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter; page->index = [%ld]; "
+ "page->mapping->host = [%p]\n", page->index,
+ page->mapping->host);
+
+ /* Sanity checkers */
+ if (1) {
+ struct address_space *mapping = page->mapping;
+ loff_t offset = (loff_t) page->index << PAGE_CACHE_SHIFT;
+ if (wbc->sync_mode != WB_SYNC_NONE) {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "wbc->sync_mode != WB_SYNC_NONE\n");
+ } else {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "wbc->sync_mode == WB_SYNC_NONE\n");
+ }
+ /* racing with truncate? */
+ if (offset > mapping->host->i_size) {
+ ecryptfs_printk(1, KERN_NOTICE, "Racing truncate\n");
+ }
+ BUG_ON(PageWriteback(page));
+ }
+
+ /* End sanity */
+
+ inode = page->mapping->host;
+ crypt_stats = &(INODE_TO_PRIVATE(inode)->crypt_stats);
+ lower_inode = INODE_TO_LOWER(inode);
+ /* The 2nd argument here should be the index of the lower file, which
+ * should be the calculated result of our index interpolation */
+ lower_index = PG_IDX_TO_LWR_PG_IDX(crypt_stats, page->index);
+ ecryptfs_printk(1, KERN_NOTICE, "Grab lower_idx = [%ld]\n",
+ lower_index);
+ lower_page = grab_cache_page(lower_inode->i_mapping, lower_index);
+ if (!lower_page) {
+ err = -ENOMEM;
+ goto out;
+ }
+ if (PageWriteback(lower_page)) {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "lower_page is under writeback\n");
+ } else {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "lower_page is avail for writeback\n");
+ }
+ if (!PageLocked(page)) {
+ ecryptfs_printk(1, KERN_NOTICE, "Page not locked\n");
+ } else {
+ ecryptfs_printk(1, KERN_NOTICE, "Page is already locked\n");
+ }
+ kaddr = (char *)kmap(page);
+ lower_kaddr = (char *)kmap(lower_page);
+ ecryptfs_printk(1, KERN_NOTICE, "Copying page\n");
+ memcpy(lower_kaddr, kaddr, crypt_stats->extent_size);
+ kunmap(page);
+ kunmap(lower_page);
+ if (PageWriteback(lower_page)) {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "lower_page is under writeback\n");
+ } else {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "lower_page is avail for writeback\n");
+ }
+ err = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
+ lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+ page_cache_release(lower_page);
+ if (err)
+ ClearPageUptodate(page);
+ else
+ SetPageUptodate(page);
+ unlock_page(page);
+out:
+ ecryptfs_printk(1, KERN_NOTICE, "Exit; err = [%d]\n", err);
+ return err;
+}
+
+/**
+ * Reads the data from the lower file file at index lower_page_index
+ * and copies that data into page.
+ *
+ * @param page Page to fill
+ * @param lower_page_index Index of the page in the lower file to get
+ */
+static int ecryptfs_do_readpage(struct file *file, struct page *page,
+ pgoff_t lower_page_index)
+{
+ int rc = -EIO;
+ struct dentry *dentry;
+ struct file *lower_file;
+ struct dentry *lower_dentry;
+ struct inode *inode;
+ struct inode *lower_inode;
+ char *page_data;
+ struct page *lower_page = NULL;
+ char *lower_page_data;
+ struct address_space_operations *lower_a_ops;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter; lower_page_index = [%lu]\n",
+ lower_page_index);
+ dentry = file->f_dentry;
+ if (NULL == FILE_TO_PRIVATE_SM(file)) {
+ rc = -ENOENT;
+ ecryptfs_printk(0, KERN_ERR, "No lower file info\n");
+ goto out;
+ }
+ lower_file = FILE_TO_LOWER(file);
+ lower_dentry = DENTRY_TO_LOWER(dentry);
+ inode = dentry->d_inode;
+ lower_inode = INODE_TO_LOWER(inode);
+ lower_a_ops = lower_inode->i_mapping->a_ops;
+ lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
+ (filler_t *) lower_a_ops->readpage,
+ (void *)lower_file);
+ if (IS_ERR(lower_page)) {
+ rc = PTR_ERR(lower_page);
+ lower_page = NULL;
+ ecryptfs_printk(0, KERN_ERR, "Error reading from page cache\n");
+ goto out;
+ }
+ wait_on_page_locked(lower_page);
+ if (!PageUptodate(lower_page)) {
+ lock_page(lower_page);
+ rc = lower_a_ops->readpage(lower_file, lower_page);
+ if (rc) {
+ lower_page = NULL;
+ rc = -EIO;
+ ecryptfs_printk(0, KERN_ERR, "Error reading lower "
+ "page at index=[%lu]\n",
+ lower_page_index);
+ goto out;
+ }
+ wait_on_page_locked(lower_page);
+ if (!PageUptodate(lower_page)) {
+ rc = -EIO;
+ ecryptfs_printk(0, KERN_ERR, "Error reading lower "
+ "page at index=[%lu]\n",
+ lower_page_index);
+ goto out;
+ }
+ }
+ page_data = (char *)kmap(page);
+ if (!page_data) {
+ rc = -ENOMEM;
+ ecryptfs_printk(0, KERN_ERR, "Error mapping page\n");
+ goto out;
+ }
+ lower_page_data = (char *)kmap(lower_page);
+ if (!lower_page_data) {
+ rc = -ENOMEM;
+ ecryptfs_printk(0, KERN_ERR, "Error mapping page\n");
+ kunmap(page);
+ goto out;
+ }
+ /* TODO: Copy sub-page amount of data? */
+ memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
+ kunmap(lower_page);
+ kunmap(page);
+ rc = 0;
+ out:
+ if (likely(lower_page)) {
+ page_cache_release(lower_page);
+ }
+ if (rc == 0)
+ SetPageUptodate(page);
+ else
+ ClearPageUptodate(page);
+ ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc);
+ return rc;
+}
+
+/* Action descriptor for decrypt_page() */
+#define ECRYPTFS_ACTION_COPY 0
+#define ECRYPTFS_ACTION_DECRYPT 1
+
+/**
+ * Decrypt a page of data
+ *
+ * @return Zero on success
+ */
+static int decrypt_page(struct ecryptfs_crypt_stats *crypt_stats,
+ struct file *file, char *iv, struct page *page,
+ pgoff_t lower_page_index, int decrypt)
+{
+ int rc = 0;
+ char *lower_page_encrypted_virt;
+ struct page *lower_page_encrypted;
+ int decrypt_to;
+
+ ecryptfs_printk(1, KERN_NOTICE, "Enter; lower_page_index = [%d]\n",
+ lower_page_index);
+ lower_page_encrypted_virt =
+ ecryptfs_kmem_cache_alloc(ecryptfs_lower_page_cache, SLAB_KERNEL);
+ if (!lower_page_encrypted_virt) {
+ rc = -ENOMEM;
+ ecryptfs_printk(0, KERN_ERR, "Error getting page for "
+ "encrypted lower page\n");
+ ClearPageUptodate(page);
+ goto out;
+ }
+ lower_page_encrypted = virt_to_page(lower_page_encrypted_virt);
+ rc = ecryptfs_do_readpage(file, lower_page_encrypted, lower_page_index);
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error reading lower encrypted "
+ "page\n");
+ ClearPageUptodate(page);
+ goto out;
+ }
+ ecryptfs_printk(1, KERN_NOTICE, "Decrypting page with iv:\n");
+ ecryptfs_dump_hex(iv, crypt_stats->iv_bytes);
+ ecryptfs_printk(1, KERN_NOTICE, "Using session key encryption key:\n");
+ ecryptfs_dump_hex(crypt_stats->key, crypt_stats->key_size_bits / 8);
+ decrypt_to = crypt_stats->extent_size;
+ ecryptfs_printk(1, KERN_NOTICE, "Decrypting to: [%d]\n", decrypt_to);
+ ecryptfs_printk(1, KERN_NOTICE, "First 8 bytes before decryption:\n");
+ ecryptfs_dump_hex((char *)page_address(lower_page_encrypted), 8);
+ if (decrypt) {
+ do_decrypt_page_offset(crypt_stats, page,
+ 0, lower_page_encrypted,
+ 0, decrypt_to, iv);
+ } else {
+ memcpy(page, lower_page_encrypted_virt, decrypt_to);
+ }
+ ecryptfs_printk(1, KERN_NOTICE, "First 8 bytes after decryption:\n");
+ ecryptfs_dump_hex((char *)page_address(page), 8);
+ ecryptfs_kmem_cache_free(ecryptfs_lower_page_cache,
+ lower_page_encrypted_virt);
+out:
+ ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc);
+ return rc;
+}
+
+/**
+ * Read in a page
+ *
+ * @param file This is an ecryptfs file
+ * @param page ecryptfs associated page to stick the read data into
+ */
+static int ecryptfs_readpage(struct file *file, struct page *page)
+{
+ int rc = 0;
+ struct ecryptfs_crypt_stats *crypt_stats = NULL;
+ char iv[ECRYPTFS_MAX_IV_BYTES];
+ int iv_is_nonzero = 0;
+ char *records_virt;
+ struct page *records_page;
+ int record_byte_offset;
+ int iv_byte_offset;
+ int i;
+ int record_size;
+ pgoff_t records_page_index;
+ pgoff_t lower_page_index;
+
+ ecryptfs_printk(1, KERN_NOTICE, "Enter; page->index = [%ld]\n",
+ page->index);
+ ASSERT(file && file->f_dentry && file->f_dentry->d_inode);
+ crypt_stats = &INODE_TO_PRIVATE(file->f_dentry->d_inode)->crypt_stats;
+ /* If the file is neither encrypted nor HMAC-verified, then we
+ * have passthrough mode. */
+ if (!crypt_stats || !crypt_stats->encrypted) {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "Passing through unencrypted page\n");
+ rc = ecryptfs_do_readpage(file, page, page->index);
+ goto out;
+ }
+ record_size = crypt_stats->iv_bytes;
+ /* The file is encrypted, hmac verified, or both. */
+ ecryptfs_printk(1, KERN_NOTICE,
+ "crypt_stats->iv_bytes = [%d]\n",
+ crypt_stats->iv_bytes);
+ ecryptfs_printk(1, KERN_NOTICE,
+ "crypt_stats->records_per_page = [%d]\n",
+ crypt_stats->records_per_page);
+
+ /* Get the relevant IV/HMAC page */
+ records_page_index = LAST_RECORDS_PAGE_IDX(crypt_stats, page->index);
+ ecryptfs_printk(1, KERN_NOTICE, "records_page_index = [%lu]\n",
+ records_page_index);
+ records_virt = (char *)__get_free_page(GFP_KERNEL);
+ if (!records_virt) {
+ ecryptfs_printk(0, KERN_ERR, "Error getting free page");
+ rc = -ENOMEM;
+ ClearPageUptodate(page);
+ goto out;
+ }
+ records_page = virt_to_page(records_virt);
+ rc = ecryptfs_do_readpage(file, records_page, records_page_index);
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error reading IV/HMAC page");
+ ClearPageUptodate(page);
+ goto out;
+ }
+
+ record_byte_offset = RECORD_IDX(crypt_stats, page->index) * record_size;
+ iv_byte_offset = -1;
+ if (crypt_stats->encrypted) {
+ iv_byte_offset = record_byte_offset;
+ iv_is_nonzero = 0;
+ for (i = 0; i < crypt_stats->iv_bytes; i++) {
+ iv_is_nonzero |= (records_virt + iv_byte_offset)[i];
+ }
+ memcpy(iv, (records_virt + iv_byte_offset),
+ crypt_stats->iv_bytes);
+ }
+ ecryptfs_printk(1, KERN_NOTICE, "record_byte_offset = [%d]\n",
+ record_byte_offset);
+ ecryptfs_printk(1, KERN_NOTICE, "iv_byte_offset = [%d]\n",
+ iv_byte_offset);
+ free_page((unsigned long)records_virt);
+ lower_page_index = PG_IDX_TO_LWR_PG_IDX(crypt_stats, page->index);
+ ecryptfs_printk(1, KERN_NOTICE, "lower_page_index = [%lu]\n",
+ lower_page_index);
+ ecryptfs_printk(1, KERN_NOTICE, "iv_is_nonzero = [%d]\n",
+ iv_is_nonzero);
+ if (crypt_stats->encrypted && iv_is_nonzero) {
+ rc = decrypt_page(crypt_stats, file, iv, page,
+ lower_page_index, ECRYPTFS_ACTION_DECRYPT);
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error decrypting "
+ "page; rc = [%d]\n", rc);
+ goto out;
+ }
+ } else {
+ ecryptfs_printk(1, KERN_NOTICE,
+ "Passing through unencrypted page\n");
+ rc = ecryptfs_do_readpage(file, page, lower_page_index);
+ }
+ SetPageUptodate(page);
+out:
+ ecryptfs_printk(1, KERN_NOTICE, "Unlocking page with index = [%lu]\n",
+ page->index);
+ unlock_page(page);
+ ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc);
+ return rc;
+}
+
+static int ecryptfs_prepare_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ int err = 0;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter; page->index = [%lu]; from = "
+ "[%d]; to = [%d]\n", page->index, from, to);
+ kmap(page);
+ if (from == 0 && to == PAGE_CACHE_SIZE)
+ goto out; /* If we are writing a full page, it will be
+ up to date. */
+ if (!PageUptodate(page))
+ err = ecryptfs_do_readpage(file, page, page->index);
+out:
+ return err;
+}
+
+/**
+ * @return Zero on success
+ */
+int
+ecryptfs_write_inode_size_to_header(struct file *lower_file,
+ struct inode *lower_inode,
+ struct inode *inode)
+{
+ int rc = 0;
+ struct page *header_page;
+ char *header_virt;
+ struct address_space_operations *lower_a_ops;
+ unsigned long long file_size;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
+ header_page = grab_cache_page(lower_inode->i_mapping, 0);
+ if (!header_page) {
+ rc = -EINVAL;
+ ecryptfs_printk(0, KERN_ERR, "grab_cache_page for header page "
+ "failed\n");
+ goto out;
+ }
+ header_virt = kmap(header_page);
+ lower_a_ops = lower_inode->i_mapping->a_ops;
+ rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
+ file_size = (unsigned long long)i_size_read(inode);
+ memcpy(header_virt, &file_size, 8);
+ rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
+ if (rc < 0) {
+ ecryptfs_printk(0, KERN_ERR, "Error commiting header page "
+ "write\n");
+ }
+ kunmap(header_page);
+ ecryptfs_printk(1, KERN_NOTICE, "Unlocking page with index = [%lu]\n",
+ header_page->index);
+ unlock_page(header_page);
+ page_cache_release(header_page);
+ lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+ mark_inode_dirty_sync(inode);
+out:
+ ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc);
+ return rc;
+}
+
+/**
+ * @return Zero on success; negative on error
+ */
+static int encrypt_page(struct ecryptfs_crypt_stats *crypt_stats,
+ struct page *page, struct page *lower_page, char *iv)
+{
+ int rc = 0;
+ ecryptfs_printk(1, KERN_NOTICE, "Calling do_encrypt_page()\n");
+ if (iv) {
+ ecryptfs_printk(1, KERN_NOTICE, "Encrypting page with iv:\n");
+ if (ecryptfs_verbosity > 0) {
+ ecryptfs_dump_hex(iv, crypt_stats->iv_bytes);
+ }
+ }
+ ecryptfs_printk(1, KERN_NOTICE, "First 8 bytes before "
+ "encryption:\n");
+ if (ecryptfs_verbosity > 0) {
+ ecryptfs_dump_hex((char *)page_address(page), 8);
+ }
+ rc = do_encrypt_page_offset(crypt_stats, lower_page, 0,
+ page, 0, crypt_stats->extent_size, iv);
+ ecryptfs_printk(1, KERN_NOTICE, "Encrypted [%d] bytes\n", rc);
+ ecryptfs_printk(1, KERN_NOTICE, "First 8 bytes after " "encryption:\n");
+ if (ecryptfs_verbosity > 0) {
+ ecryptfs_dump_hex((char *)page_address(lower_page), 8);
+ }
+ if (rc > 0)
+ rc = 0;
+ return rc;
+}
+
+/**
+ * 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.
+ *
+ * @param file The eCryptfs file object
+ * @param page The eCryptfs page
+ * @param from Ignored (we rotate the page IV on each write)
+ * @param to Ignored
+ * @return
+ */
+static int ecryptfs_commit_write(struct file *file, struct page *page,
+ unsigned from, unsigned to)
+{
+ int rc = -ENOMEM;
+ struct inode *inode;
+ struct inode *lower_inode;
+ struct page *lower_page = NULL;
+ struct file *lower_file = NULL;
+ loff_t pos;
+ unsigned bytes = to - from;
+ struct ecryptfs_crypt_stats *crypt_stats;
+ pgoff_t lower_page_index;
+ struct page *records_page;
+ struct address_space_operations *lower_a_ops;
+ struct dentry *ecryptfs_dentry;
+ ecryptfs_printk(1, KERN_NOTICE,
+ "Enter; page->index = [%lu]; from = [%d]; to = [%d]\n",
+ page->index, from, to);
+ ecryptfs_dentry = file->f_dentry;
+ inode = page->mapping->host;
+ lower_inode = INODE_TO_LOWER(inode);
+ down(&lower_inode->i_sem);
+ if (!(lower_inode->i_mapping
+ && lower_inode->i_mapping->a_ops
+ && lower_inode->i_mapping->a_ops->prepare_write
+ && lower_inode->i_mapping->a_ops->commit_write)) {
+ ecryptfs_printk(0, KERN_ERR,
+ "a_ops of lower inode not valid\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ lower_a_ops = lower_inode->i_mapping->a_ops;
+ ASSERT(file && file->f_dentry && file->f_dentry->d_inode);
+ crypt_stats = &INODE_TO_PRIVATE(file->f_dentry->d_inode)->crypt_stats;
+ if (NULL != FILE_TO_PRIVATE(file))
+ lower_file = FILE_TO_LOWER(file);
+ if (!crypt_stats) {
+ rc = -EINVAL;
+ goto out;
+ }
+
+ rc = ecryptfs_init_crypt_ctx(crypt_stats);
+ if (rc) {
+ ecryptfs_printk(1, KERN_NOTICE, "Problem with "
+ "initializing crypto context\n");
+ }
+
+ if (crypt_stats->new_file) {
+ struct page *header_page;
+ char *header_virt;
+ crypt_stats->new_file = 0;
+ header_page = grab_cache_page(lower_inode->i_mapping, 0);
+ if (!header_page) {
+ rc = -EINVAL;
+ ecryptfs_printk(0, KERN_ERR, "grab_cache_page for "
+ "header page failed\n");
+ goto out;
+ }
+ header_virt = kmap(header_page);
+ rc = lower_a_ops->prepare_write(lower_file, header_page,
+ 0, crypt_stats->extent_size);
+ rc = ecryptfs_generate_key_packet_set(
+ header_virt, (ECRYPTFS_FILE_SIZE_BYTES
+ + MAGIC_ECRYPTFS_MARKER_SIZE_BYTES),
+ crypt_stats, ecryptfs_dentry);
+ memset(header_virt, 0, 8);
+ rc = lower_a_ops->commit_write(lower_file, header_page,
+ 0, crypt_stats->extent_size);
+ if (rc < 0) {
+ ecryptfs_printk(0, KERN_ERR, "Error commiting header "
+ "page write\n");
+ }
+ kunmap(header_page);
+ ecryptfs_printk(1, KERN_NOTICE,
+ "Unlocking header page with index = " "[%lu]\n",
+ header_page->index);
+ unlock_page(header_page);
+ page_cache_release(header_page);
+ if (rc < 0) {
+ goto out;
+ }
+ rc = 0;
+ ecryptfs_printk(1, KERN_NOTICE, "lower_inode->i_blocks = "
+ "[%lu]\n", lower_inode->i_blocks);
+ i_size_write(inode, 0);
+ lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+ mark_inode_dirty_sync(inode);
+ } else {
+ ecryptfs_printk(1, KERN_NOTICE, "Not a new file\n");
+ }
+ /* Translate the page index */
+ lower_page_index = PG_IDX_TO_LWR_PG_IDX(crypt_stats, page->index);
+ ecryptfs_printk(1, KERN_NOTICE, "lower_page_index = [%lu]\n",
+ lower_page_index);
+ lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
+ if (!lower_page) {
+ ecryptfs_printk(0, KERN_ERR, "grab_cache_page for "
+ "lower_page_index=[%lu] failed\n",
+ lower_page_index);
+ goto out;
+ }
+ kmap(lower_page);
+ rc = lower_a_ops->prepare_write(lower_file, lower_page,
+ 0, crypt_stats->extent_size);
+ if (rc) {
+ goto out_unlock_lower;
+ }
+ if (!crypt_stats->encrypted) {
+ /* TODO: aops */
+ memcpy((char *)page_address(lower_page),
+ (char *)page_address(page), crypt_stats->extent_size);
+ } else {
+ /* The file is either encrypted or HMAC'd */
+ pgoff_t records_page_index;
+ int record_byte_offset = -1;
+ int iv_byte_offset = -1;
+ char *records_virt;
+ char iv[ECRYPTFS_MAX_IV_BYTES];
+ int record_size;
+ ecryptfs_printk(1, KERN_NOTICE,
+ "crypt_stats->iv_bytes = [%d]\n",
+ crypt_stats->iv_bytes);
+ ecryptfs_printk(1, KERN_NOTICE,
+ "crypt_stats->records_per_page = [%d]\n",
+ crypt_stats->records_per_page);
+ record_size = crypt_stats->iv_bytes;
+ records_page_index =
+ LAST_RECORDS_PAGE_IDX(crypt_stats, page->index);
+ ecryptfs_printk(1, KERN_NOTICE, "records_page_index = [%lu]\n",
+ records_page_index);
+ records_page = grab_cache_page(lower_inode->i_mapping,
+ records_page_index);
+ if (!records_page) {
+ ecryptfs_printk(0, KERN_ERR, "records_page == NULL "
+ "after grab_cache_page at index [%lu]"
+ "\n", records_page_index);
+ rc = -EIO;
+ goto out_unlock_lower;
+ }
+ iv_byte_offset = -1;
+ record_byte_offset =
+ RECORD_IDX(crypt_stats, page->index) * record_size;
+ if (crypt_stats->encrypted) {
+ iv_byte_offset = record_byte_offset;
+ }
+ ecryptfs_printk(1, KERN_NOTICE, "iv_byte_offset = [%d]\n",
+ iv_byte_offset);
+ records_virt = kmap(records_page);
+ rc = lower_a_ops->prepare_write(lower_file, records_page,
+ iv_byte_offset,
+ iv_byte_offset
+ + crypt_stats->iv_bytes);
+ down(&crypt_stats->iv_sem);
+ ecryptfs_rotate_iv(crypt_stats->iv);
+ memcpy(iv, crypt_stats->iv, crypt_stats->iv_bytes);
+ up(&crypt_stats->iv_sem);
+ memcpy(records_virt + iv_byte_offset, crypt_stats->iv,
+ crypt_stats->iv_bytes);
+ rc = lower_a_ops->commit_write(lower_file, records_page,
+ iv_byte_offset,
+ iv_byte_offset +
+ crypt_stats->iv_bytes);
+ kunmap(records_page);
+ lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+ mark_inode_dirty_sync(inode);
+ ecryptfs_printk(1, KERN_NOTICE, "Unlocking page with index = "
+ "[%lu]\n", records_page->index);
+ unlock_page(records_page);
+ page_cache_release(records_page);
+ ecryptfs_printk(1, KERN_NOTICE, "After committing IV write, "
+ "lower_inode->i_blocks = [%lu]\n",
+ lower_inode->i_blocks);
+ ecryptfs_printk(1, KERN_NOTICE, "Encrypting page with iv:\n");
+ if (ecryptfs_verbosity > 0) {
+ ecryptfs_dump_hex(iv, crypt_stats->iv_bytes);
+ }
+ rc = encrypt_page(crypt_stats, page, lower_page, iv);
+ if (rc) {
+ ecryptfs_printk(0, KERN_WARNING, "Error encrypting "
+ "page\n");
+ goto out;
+ }
+ }
+ rc = lower_a_ops->commit_write(lower_file, lower_page, 0,
+ crypt_stats->extent_size);
+ if (rc < 0) {
+ ecryptfs_printk(0, KERN_ERR,
+ "Error committing write; rc = [%d]\n", rc);
+ goto out_unlock_lower;
+ }
+ rc = bytes;
+ inode->i_blocks = lower_inode->i_blocks;
+ pos = (page->index << PAGE_CACHE_SHIFT) + to;
+ if (pos > i_size_read(inode)) {
+ i_size_write(inode, pos);
+ ecryptfs_printk(1, KERN_NOTICE, "Expanded file size to "
+ "[%lld]\n", i_size_read(inode));
+ }
+ ecryptfs_write_inode_size_to_header(lower_file, lower_inode, inode);
+ lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+ mark_inode_dirty_sync(inode);
+
+out_unlock_lower:
+ kunmap(lower_page);
+ ecryptfs_printk(1, KERN_NOTICE,
+ "Unlocking lower page with index = [%lu]\n",
+ lower_page->index);
+ unlock_page(lower_page);
+ page_cache_release(lower_page);
+ kunmap(page); /* mapped in prepare_write */
+out:
+ if (rc < 0)
+ ClearPageUptodate(page);
+ else
+ SetPageUptodate(page);
+ up(&lower_inode->i_sem);
+ ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc);
+ return rc;
+}
+
+static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
+{
+ int rc = 0;
+ struct inode *inode;
+ struct inode *lower_inode;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
+ inode = (struct inode *)mapping->host;
+ lower_inode = 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;
+}
+
+/**
+ * This function is copied verbatim from mm/filemap.c. It should be
+ * simply moved to some header file instead.
+ */
+static int sync_page(struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
+ if (mapping && mapping->a_ops && mapping->a_ops->sync_page)
+ return mapping->a_ops->sync_page(page);
+ return 0;
+}
+
+static int ecryptfs_sync_page(struct page *page)
+{
+ int rc = 0;
+ struct inode *inode;
+ struct inode *lower_inode;
+ struct page *lower_page;
+ ecryptfs_printk(1, KERN_NOTICE, "Enter\n");
+ inode = page->mapping->host;
+ lower_inode = INODE_TO_LOWER(inode);
+ lower_page = grab_cache_page(lower_inode->i_mapping, page->index);
+ if (!lower_page) {
+ rc = -ENOMEM;
+ ecryptfs_printk(0, KERN_ERR, "Error from grab_cache_page "
+ "(no mem?)\n");
+ goto out;
+ }
+ rc = sync_page(lower_page);
+ ecryptfs_printk(1, KERN_NOTICE, "Unlocking page with index = [%lu]\n",
+ lower_page->index);
+ unlock_page(lower_page);
+ page_cache_release(lower_page);
+out:
+ 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,
+ .sync_page = ecryptfs_sync_page,
+};