[PATCH 10/12: eCryptfs] Mmap operations
From: Phillip Hellewell
Date: Fri Nov 18 2005 - 23:22:21 EST
eCryptfs mmap operations. The bulk encryption and decryption takes
place here.
Signed-off-by: Phillip Hellewell <phillip@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Halcrow <mhalcrow@xxxxxxxxxx>
Signed-off-by: Michael Thompson <mcthomps@xxxxxxxxxx>
---
mmap.c | 1153 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 1153 insertions(+)
--- linux-2.6.15-rc1-mm1/fs/ecryptfs/mmap.c 1969-12-31 18:00:00.000000000 -0600
+++ linux-2.6.15-rc1-mm1-ecryptfs/fs/ecryptfs/mmap.c 2005-11-18 11:20:09.000000000 -0600
@@ -0,0 +1,1153 @@
+/**
+ * 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@xxxxxxxxxx>
+ *
+ * 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 <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;
+
+static inline pgoff_t
+record_idx(struct ecryptfs_crypt_stats *crypt_stats, pgoff_t idx)
+{
+ return (idx % crypt_stats->records_per_page);
+}
+
+static inline pgoff_t
+last_records_page_idx(struct ecryptfs_crypt_stats *crypt_stats, pgoff_t idx)
+{
+ pgoff_t lower_data_idx;
+ pgoff_t lower_record_idx;
+
+ lower_data_idx = ecryptfs_pg_idx_to_lwr_pg_idx(crypt_stats, idx);
+ lower_record_idx = record_idx(crypt_stats, idx);
+ return (lower_data_idx - lower_record_idx - 1);
+}
+
+/**
+ * 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 lower_file Can be NULL
+ * @return Zero on success
+ */
+static int
+ecryptfs_read_rotate_write_iv(char *iv, struct inode *inode,
+ int lower_iv_idx, struct file *lower_file,
+ struct page *page)
+{
+ int rc = 0;
+ pgoff_t records_page_index;
+ struct ecryptfs_crypt_stats *crypt_stats;
+ struct page *records_page;
+ char *records_virt;
+ int lower_file_needs_fput = 0;
+ struct address_space_operations *lower_a_ops;
+ struct inode *lower_inode;
+
+ crypt_stats = &(ECRYPTFS_INODE_TO_PRIVATE(inode)->crypt_stats);
+ lower_inode = ECRYPTFS_INODE_TO_LOWER(inode);
+ lower_a_ops = lower_inode->i_mapping->a_ops;
+ 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;
+ }
+ /* TODO: Assume encrypted only for version 0.1 */
+ ecryptfs_printk(1, KERN_NOTICE, "lower_iv_idx = [%d]\n", lower_iv_idx);
+ records_virt = kmap(records_page);
+ if (!records_virt) {
+ rc = -ENOMEM;
+ ecryptfs_printk(1, KERN_NOTICE, "Error in kmap\n");
+ goto out_unlock_and_release;
+ }
+ if (!lower_file) {
+ struct dentry *lower_dentry;
+ struct vfsmount *lower_mnt;
+
+ if (!lower_inode->i_dentry.next) {
+ rc = -EINVAL;
+ ecryptfs_printk(1, KERN_NOTICE, "No dentry for "
+ "lower_inode\n");
+ goto out_unmap;
+ }
+ lower_dentry = list_entry(lower_inode->i_dentry.next,
+ struct dentry, d_alias);
+ mntget(ECRYPTFS_SUPERBLOCK_TO_PRIVATE(inode->i_sb)->lower_mnt);
+ lower_mnt =
+ ECRYPTFS_SUPERBLOCK_TO_PRIVATE(inode->i_sb)->lower_mnt;
+ lower_file = dentry_open(lower_dentry, lower_mnt, FMODE_READ);
+ if (IS_ERR(lower_file)) {
+ rc = PTR_ERR(lower_file);
+ ecryptfs_printk(0, KERN_ERR,
+ "Error opening dentry; rc = [%i]\n",
+ rc);
+ mntput(ECRYPTFS_SUPERBLOCK_TO_PRIVATE(inode->i_sb)->lower_mnt);
+ goto out_unmap;
+ }
+ lower_file_needs_fput = 1;
+ }
+ rc = lower_a_ops->prepare_write(lower_file, records_page, lower_iv_idx,
+ (lower_iv_idx + crypt_stats->iv_bytes));
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error in lower prepare_write() "
+ "call: rc = [%d]\n", rc);
+ goto out_unmap;
+ }
+ 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 + lower_iv_idx, crypt_stats->iv,
+ crypt_stats->iv_bytes);
+ rc = lower_a_ops->commit_write(lower_file, records_page, lower_iv_idx,
+ (lower_iv_idx + crypt_stats->iv_bytes));
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error in lower commit_write() "
+ "call: rc = [%d]\n", rc);
+ goto out_unmap;
+ }
+ lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+ ecryptfs_printk(1, KERN_NOTICE, "Unlocking page with index = "
+ "[%lu]\n", records_page->index);
+out_unmap:
+ kunmap(records_page);
+out_unlock_and_release:
+ 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);
+out:
+ if (lower_file_needs_fput)
+ fput(lower_file);
+ 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");
+ ecryptfs_printk(1, KERN_NOTICE, "Encrypting page with iv:\n");
+ if (unlikely(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;
+}
+
+/**
+ * @param page Page that is locked before this call is made
+ */
+static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
+{
+ int rc = -EIO;
+ int err = 0;
+ 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);
+ inode = page->mapping->host;
+ crypt_stats = &(ECRYPTFS_INODE_TO_PRIVATE(inode)->crypt_stats);
+ lower_inode = ECRYPTFS_INODE_TO_LOWER(inode);
+ lower_index = ecryptfs_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) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ kaddr = (char *)kmap(page);
+ if (!kaddr) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ lower_kaddr = (char *)kmap(lower_page);
+ if (!lower_kaddr) {
+ rc = -ENOMEM;
+ goto out;
+ }
+ if (crypt_stats->encrypted) {
+ char iv[ECRYPTFS_MAX_IV_BYTES];
+ int record_byte_offset;
+ /* TODO: HMAC: Include HMAC bytes in the record size */
+ record_byte_offset = (record_idx(crypt_stats, page->index)
+ * crypt_stats->iv_bytes);
+ rc = ecryptfs_read_rotate_write_iv(iv, inode,
+ record_byte_offset, NULL,
+ page);
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error rotating "
+ "IV; write failure. Assuming "
+ "IV page corruption; writing "
+ "0's to associated data extent"
+ ".\n");
+ memset(lower_kaddr, 0, crypt_stats->extent_size);
+ err = -EIO;
+ goto do_lower_write;
+ }
+ ecryptfs_printk(1, KERN_NOTICE, "Encrypting page with iv:\n");
+ if (unlikely(ecryptfs_verbosity > 0))
+ ecryptfs_dump_hex(iv, crypt_stats->iv_bytes);
+ err = encrypt_page(crypt_stats, page, lower_page, iv);
+ if (err)
+ ecryptfs_printk(0, KERN_WARNING, "Error encrypting "
+ "page (upper index [%llu])\n",
+ page->index);
+ } else
+ memcpy(lower_kaddr, kaddr, crypt_stats->extent_size);
+do_lower_write:
+ kunmap(page);
+ kunmap(lower_page);
+ rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
+ if (rc)
+ ecryptfs_printk(0, KERN_ERR, "Error calling lower writepage(); "
+ "rc = [%d]\n", rc);
+ lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
+ page_cache_release(lower_page);
+ if (rc)
+ ClearPageUptodate(page);
+ else
+ SetPageUptodate(page);
+ unlock_page(page);
+out:
+ if (err)
+ rc = err;
+ ecryptfs_printk(1, KERN_NOTICE, "Exit; rc = [%d]\n", rc);
+ return rc;
+}
+
+/**
+ * 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 == ECRYPTFS_FILE_TO_PRIVATE_SM(file)) {
+ rc = -ENOENT;
+ ecryptfs_printk(0, KERN_ERR, "No lower file info\n");
+ goto out;
+ }
+ lower_file = ECRYPTFS_FILE_TO_LOWER(file);
+ lower_dentry = ECRYPTFS_DENTRY_TO_LOWER(dentry);
+ inode = dentry->d_inode;
+ lower_inode = ECRYPTFS_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 =
+ 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");
+ if (ecryptfs_verbosity > 0)
+ ecryptfs_dump_hex(iv, crypt_stats->iv_bytes);
+ ecryptfs_printk(1, KERN_NOTICE, "Using session key encryption key:\n");
+ if (ecryptfs_verbosity > 0)
+ 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");
+ if (ecryptfs_verbosity > 0)
+ 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");
+ if (ecryptfs_verbosity > 0)
+ ecryptfs_dump_hex((char *)page_address(page), 8);
+ 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
+ * @return Zero on success; non-zero on error
+ */
+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;
+ 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 =
+ &ECRYPTFS_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;
+ }
+ /* 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;
+ }
+ /* TODO: HMAC: Include HMAC bytes in the record size */
+ record_byte_offset = (record_idx(crypt_stats, page->index)
+ * crypt_stats->iv_bytes);
+ 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 = ecryptfs_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 void fill_zeros_to_end_of_page(struct page *page, unsigned to)
+{
+ struct inode *inode = page->mapping->host;
+ int end_byte_in_page;
+ char *page_virt;
+
+ if ((i_size_read(inode) / PAGE_CACHE_SIZE) == page->index) {
+ end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
+ if (to > end_byte_in_page)
+ end_byte_in_page = to;
+ page_virt = kmap(page);
+ if (!page_virt) {
+ goto out;
+ }
+ memset((page_virt + end_byte_in_page), 0,
+ (PAGE_CACHE_SIZE - end_byte_in_page));
+ kunmap(page);
+ }
+out:
+ return;
+}
+
+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;
+}
+
+/**
+ * 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 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 = ECRYPTFS_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 =
+ &ECRYPTFS_INODE_TO_PRIVATE(file->f_dentry->d_inode)->crypt_stats;
+ if (NULL != ECRYPTFS_FILE_TO_PRIVATE(file))
+ lower_file = ECRYPTFS_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_write_headers_virt(header_virt, crypt_stats,
+ ecryptfs_dentry,
+ ECRYPTFS_FILE_VERSION);
+ if (rc) {
+ ecryptfs_printk(0, KERN_WARNING, "Error generating "
+ "header; rc = [%d]\n", rc);
+ rc = -EIO;
+ goto out;
+ }
+ 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 = ecryptfs_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;
+ fill_zeros_to_end_of_page(page, to);
+ 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 */
+ char iv[ECRYPTFS_MAX_IV_BYTES];
+ int record_byte_offset;
+ ecryptfs_printk(1, KERN_NOTICE,
+ "crypt_stats->iv_bytes = [%d]\n",
+ crypt_stats->iv_bytes);
+ /* TODO: HMAC: Include HMAC bytes in the record size */
+ record_byte_offset = (record_idx(crypt_stats, page->index)
+ * crypt_stats->iv_bytes);
+ rc = ecryptfs_read_rotate_write_iv(iv, inode,
+ record_byte_offset,
+ lower_file, page);
+ if (rc) {
+ ecryptfs_printk(0, KERN_ERR, "Error rotating IV\n");
+ goto out_unlock_lower;
+ }
+ ecryptfs_printk(1, KERN_NOTICE, "Encrypting page with iv:\n");
+ if (unlikely(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 (upper index [%llu])\n",
+ page->index);
+ 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 = 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;
+}
+
+/**
+ * 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 = ECRYPTFS_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,
+};
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