2.6.24

 fs

 ecryptfs

diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
new file mode 100644
index 0000000..948f576
--- /dev/null
+++ b/fs/ecryptfs/read_write.c
@@ -0,0 +1,373 @@
+/**
+ * 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 = ((((loff_t)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;
+   loff_t ecryptfs_file_size =
+      i_size_read(ecryptfs_file->f_dentry->d_inode);
+   loff_t data_offset = 0;
+   loff_t pos;
+   int rc = 0;
+
+   /*
+    * if we are writing beyond current size, then start pos
+    * at the current size - we'll fill in zeros from there.
+    */
+   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) {
+         /* remaining zeros to write, up to destination offset */
+         size_t total_remaining_zeros = (offset - pos);
+
+         if (num_bytes > total_remaining_zeros)
+            num_bytes = total_remaining_zeros;
+      }
+      ecryptfs_page = ecryptfs_get_locked_page(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 */
+         rc = ecryptfs_decrypt_page(ecryptfs_page);
+         if (rc) {
+            printk(KERN_ERR "%s: Error decrypting "
+                   "page; rc = [%d]\n",
+                   __FUNCTION__, rc);
+            ClearPageUptodate(ecryptfs_page);
+            page_cache_release(ecryptfs_page);
+            goto out;
+         }
+      }
+      ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0);
+
+      /*
+       * pos: where we're now writing, offset: where the request was
+       * If current pos is before request, we are filling zeros
+       * If we are at or beyond request, we are writing the *data*
+       * If we're in a fresh page beyond eof, zero it in either case
+       */
+      if (pos < offset || !start_offset_in_page) {
+         /* We are extending past the previous end of the file.
+          * Fill in zero values to the end of the page */
+         memset(((char *)ecryptfs_page_virt
+            + start_offset_in_page), 0,
+            PAGE_CACHE_SIZE - start_offset_in_page);
+      }
+
+      /* pos >= offset, we are now writing the data request */
+      if (pos >= offset) {
+         memcpy(((char *)ecryptfs_page_virt
+            + start_offset_in_page),
+                (data + data_offset), num_bytes);
+         data_offset += num_bytes;
+      }
+      kunmap_atomic(ecryptfs_page_virt, KM_USER0);
+      flush_dcache_page(ecryptfs_page);
+      SetPageUptodate(ecryptfs_page);
+      unlock_page(ecryptfs_page);
+      rc = ecryptfs_encrypt_page(ecryptfs_page);
+      page_cache_release(ecryptfs_page);
+      if (rc) {
+         printk(KERN_ERR "%s: Error encrypting "
+                "page; rc = [%d]\n", __FUNCTION__, rc);
+         goto out;
+      }
+      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(
+         ecryptfs_file->f_dentry->d_inode);
+      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;
+   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);
+   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 = ((((loff_t)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);
+   flush_dcache_page(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;
+   loff_t 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_get_locked_page(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(ecryptfs_page);
+      if (rc) {
+         printk(KERN_ERR "%s: Error decrypting "
+                "page; rc = [%d]\n", __FUNCTION__, rc);
+         ClearPageUptodate(ecryptfs_page);
+         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);
+      flush_dcache_page(ecryptfs_page);
+      SetPageUptodate(ecryptfs_page);
+      unlock_page(ecryptfs_page);
+      page_cache_release(ecryptfs_page);
+      pos += num_bytes;
+      data_offset += num_bytes;
+   }
+out:
+   return rc;
+}