fs/ecryptfs/mmap.c

   1 /**
   2  * eCryptfs: Linux filesystem encryption layer
   3  * This is where eCryptfs coordinates the symmetric encryption and
   4  * decryption of the file data as it passes between the lower
   5  * encrypted file and the upper decrypted file.
   6  *
   7  * Copyright (C) 1997-2003 Erez Zadok
   8  * Copyright (C) 2001-2003 Stony Brook University
   9  * Copyright (C) 2004-2007 International Business Machines Corp.
  10  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License as
  14  * published by the Free Software Foundation; either version 2 of the
  15  * License, or (at your option) any later version.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU General Public License
  23  * along with this program; if not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
  25  * 02111-1307, USA.
  26  */
  27
  28 #include <linux/pagemap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/page-flags.h>
  31 #include <linux/mount.h>
  32 #include <linux/file.h>
  33 #include <linux/crypto.h>
  34 #include <linux/scatterlist.h>
  35 #include "ecryptfs_kernel.h"
  36
  37 struct kmem_cache *ecryptfs_lower_page_cache;
  38
  39 /**
  40  * ecryptfs_get1page
  41  *
  42  * Get one page from cache or lower f/s, return error otherwise.
  43  *
  44  * Returns unlocked and up-to-date page (if ok), with increased
  45  * refcnt.
  46  */
  47 static struct page *ecryptfs_get1page(struct file *file, int index)
  48 {
  49         struct page *page;
  50         struct dentry *dentry;
  51         struct inode *inode;
  52         struct address_space *mapping;
  53
  54         dentry = file->f_path.dentry;
  55         inode = dentry->d_inode;
  56         mapping = inode->i_mapping;
  57         page = read_cache_page(mapping, index,
  58                                (filler_t *)mapping->a_ops->readpage,
  59                                (void *)file);
  60         if (IS_ERR(page))
  61                 goto out;
  62         wait_on_page_locked(page);
  63 out:
  64         return page;
  65 }
  66
  67 static
  68 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros);
  69
  70 /**
  71  * ecryptfs_fill_zeros
  72  * @file: The ecryptfs file
  73  * @new_length: The new length of the data in the underlying file;
  74  *              everything between the prior end of the file and the
  75  *              new end of the file will be filled with zero's.
  76  *              new_length must be greater than  current length
  77  *
  78  * Function for handling lseek-ing past the end of the file.
  79  *
  80  * This function does not support shrinking, only growing a file.
  81  *
  82  * Returns zero on success; non-zero otherwise.
  83  */
  84 int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
  85 {
  86         int rc = 0;
  87         struct dentry *dentry = file->f_path.dentry;
  88         struct inode *inode = dentry->d_inode;
  89         pgoff_t old_end_page_index = 0;
  90         pgoff_t index = old_end_page_index;
  91         int old_end_pos_in_page = -1;
  92         pgoff_t new_end_page_index;
  93         int new_end_pos_in_page;
  94         loff_t cur_length = i_size_read(inode);
  95
  96         if (cur_length != 0) {
  97                 index = old_end_page_index =
  98                     ((cur_length - 1) >> PAGE_CACHE_SHIFT);
  99                 old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
 100         }
 101         new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
 102         new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
 103         ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; "
 104                         "old_end_pos_in_page = [%d]; "
 105                         "new_end_page_index = [0x%.16x]; "
 106                         "new_end_pos_in_page = [%d]\n",
 107                         old_end_page_index, old_end_pos_in_page,
 108                         new_end_page_index, new_end_pos_in_page);
 109         if (old_end_page_index == new_end_page_index) {
 110                 /* Start and end are in the same page; we just need to
 111                  * set a portion of the existing page to zero's */
 112                 rc = write_zeros(file, index, (old_end_pos_in_page + 1),
 113                                  (new_end_pos_in_page - old_end_pos_in_page));
 114                 if (rc)
 115                         ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 116                                         "index=[0x%.16x], "
 117                                         "old_end_pos_in_page=[d], "
 118                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
 119                                         "=[%d]"
 120                                         ")=[d]) returned [%d]\n", file, index,
 121                                         old_end_pos_in_page,
 122                                         new_end_pos_in_page,
 123                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
 124                                         rc);
 125                 goto out;
 126         }
 127         /* Fill the remainder of the previous last page with zeros */
 128         rc = write_zeros(file, index, (old_end_pos_in_page + 1),
 129                          ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
 130         if (rc) {
 131                 ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 132                                 "index=[0x%.16x], old_end_pos_in_page=[d], "
 133                                 "(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
 134                                 "returned [%d]\n", file, index,
 135                                 old_end_pos_in_page,
 136                                 (PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
 137                 goto out;
 138         }
 139         index++;
 140         while (index < new_end_page_index) {
 141                 /* Fill all intermediate pages with zeros */
 142                 rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
 143                 if (rc) {
 144                         ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 145                                         "index=[0x%.16x], "
 146                                         "old_end_pos_in_page=[d], "
 147                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
 148                                         "=[%d]"
 149                                         ")=[d]) returned [%d]\n", file, index,
 150                                         old_end_pos_in_page,
 151                                         new_end_pos_in_page,
 152                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
 153                                         rc);
 154                         goto out;
 155                 }
 156                 index++;
 157         }
 158         /* Fill the portion at the beginning of the last new page with
 159          * zero's */
 160         rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
 161         if (rc) {
 162                 ecryptfs_printk(KERN_ERR, "write_zeros(file="
 163                                 "[%p], index=[0x%.16x], 0, "
 164                                 "new_end_pos_in_page=[%d]"
 165                                 "returned [%d]\n", file, index,
 166                                 new_end_pos_in_page, rc);
 167                 goto out;
 168         }
 169 out:
 170         return rc;
 171 }
 172
 173 /**
 174  * ecryptfs_writepage
 175  * @page: Page that is locked before this call is made
 176  *
 177  * Returns zero on success; non-zero otherwise
 178  */
 179 static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
 180 {
 181         struct ecryptfs_page_crypt_context ctx;
 182         int rc;
 183
 184         ctx.page = page;
 185         ctx.mode = ECRYPTFS_WRITEPAGE_MODE;
 186         ctx.param.wbc = wbc;
 187         rc = ecryptfs_encrypt_page(&ctx);
 188         if (rc) {
 189                 ecryptfs_printk(KERN_WARNING, "Error encrypting "
 190                                 "page (upper index [0x%.16x])\n", page->index);
 191                 ClearPageUptodate(page);
 192                 goto out;
 193         }
 194         SetPageUptodate(page);
 195         unlock_page(page);
 196 out:
 197         return rc;
 198 }
 199
 200 /**
 201  * Reads the data from the lower file file at index lower_page_index
 202  * and copies that data into page.
 203  *
 204  * @param page  Page to fill
 205  * @param lower_page_index Index of the page in the lower file to get
 206  */
 207 int ecryptfs_do_readpage(struct file *file, struct page *page,
 208                          pgoff_t lower_page_index)
 209 {
 210         int rc;
 211         struct dentry *dentry;
 212         struct file *lower_file;
 213         struct dentry *lower_dentry;
 214         struct inode *inode;
 215         struct inode *lower_inode;
 216         char *page_data;
 217         struct page *lower_page = NULL;
 218         char *lower_page_data;
 219         const struct address_space_operations *lower_a_ops;
 220
 221         dentry = file->f_path.dentry;
 222         lower_file = ecryptfs_file_to_lower(file);
 223         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 224         inode = dentry->d_inode;
 225         lower_inode = ecryptfs_inode_to_lower(inode);
 226         lower_a_ops = lower_inode->i_mapping->a_ops;
 227         lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
 228                                      (filler_t *)lower_a_ops->readpage,
 229                                      (void *)lower_file);
 230         if (IS_ERR(lower_page)) {
 231                 rc = PTR_ERR(lower_page);
 232                 lower_page = NULL;
 233                 ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
 234                 goto out;
 235         }
 236         wait_on_page_locked(lower_page);
 237         page_data = kmap_atomic(page, KM_USER0);
 238         lower_page_data = kmap_atomic(lower_page, KM_USER1);
 239         memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
 240         kunmap_atomic(lower_page_data, KM_USER1);
 241         flush_dcache_page(lower_page);
 242         kunmap_atomic(page_data, KM_USER0);
 243         flush_dcache_page(page);
 244         rc = 0;
 245 out:
 246         if (likely(lower_page))
 247                 page_cache_release(lower_page);
 248         if (rc == 0)
 249                 SetPageUptodate(page);
 250         else
 251                 ClearPageUptodate(page);
 252         return rc;
 253 }
 254 /**
 255  *   Header Extent:
 256  *     Octets 0-7:        Unencrypted file size (big-endian)
 257  *     Octets 8-15:       eCryptfs special marker
 258  *     Octets 16-19:      Flags
 259  *      Octet 16:         File format version number (between 0 and 255)
 260  *      Octets 17-18:     Reserved
 261  *      Octet 19:         Bit 1 (lsb): Reserved
 262  *                        Bit 2: Encrypted?
 263  *                        Bits 3-8: Reserved
 264  *     Octets 20-23:      Header extent size (big-endian)
 265  *     Octets 24-25:      Number of header extents at front of file
 266  *                        (big-endian)
 267  *     Octet  26:         Begin RFC 2440 authentication token packet set
 268  */
 269 static void set_header_info(char *page_virt,
 270                             struct ecryptfs_crypt_stat *crypt_stat)
 271 {
 272         size_t written;
 273         int save_num_header_extents_at_front =
 274                 crypt_stat->num_header_extents_at_front;
 275
 276         crypt_stat->num_header_extents_at_front = 1;
 277         ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
 278         crypt_stat->num_header_extents_at_front =
 279                 save_num_header_extents_at_front;
 280 }
 281
 282 /**
 283  * ecryptfs_readpage
 284  * @file: This is an ecryptfs file
 285  * @page: ecryptfs associated page to stick the read data into
 286  *
 287  * Read in a page, decrypting if necessary.
 288  *
 289  * Returns zero on success; non-zero on error.
 290  */
 291 static int ecryptfs_readpage(struct file *file, struct page *page)
 292 {
 293         int rc = 0;
 294         struct ecryptfs_crypt_stat *crypt_stat;
 295
 296         BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
 297         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 298                         ->crypt_stat;
 299         if (!crypt_stat
 300             || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
 301             || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
 302                 ecryptfs_printk(KERN_DEBUG,
 303                                 "Passing through unencrypted page\n");
 304                 rc = ecryptfs_do_readpage(file, page, page->index);
 305                 if (rc) {
 306                         ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
 307                                         "[%d]\n", rc);
 308                         goto out;
 309                 }
 310         } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
 311                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
 312                         int num_pages_in_header_region =
 313                                 (crypt_stat->header_extent_size
 314                                  / PAGE_CACHE_SIZE);
 315
 316                         if (page->index < num_pages_in_header_region) {
 317                                 char *page_virt;
 318
 319                                 page_virt = kmap_atomic(page, KM_USER0);
 320                                 memset(page_virt, 0, PAGE_CACHE_SIZE);
 321                                 if (page->index == 0) {
 322                                         rc = ecryptfs_read_xattr_region(
 323                                                 page_virt, file->f_path.dentry);
 324                                         set_header_info(page_virt, crypt_stat);
 325                                 }
 326                                 kunmap_atomic(page_virt, KM_USER0);
 327                                 flush_dcache_page(page);
 328                                 if (rc) {
 329                                         printk(KERN_ERR "Error reading xattr "
 330                                                "region\n");
 331                                         goto out;
 332                                 }
 333                         } else {
 334                                 rc = ecryptfs_do_readpage(
 335                                         file, page,
 336                                         (page->index
 337                                          - num_pages_in_header_region));
 338                                 if (rc) {
 339                                         printk(KERN_ERR "Error reading page; "
 340                                                "rc = [%d]\n", rc);
 341                                         goto out;
 342                                 }
 343                         }
 344                 } else {
 345                         rc = ecryptfs_do_readpage(file, page, page->index);
 346                         if (rc) {
 347                                 printk(KERN_ERR "Error reading page; rc = "
 348                                        "[%d]\n", rc);
 349                                 goto out;
 350                         }
 351                 }
 352         } else {
 353                 rc = ecryptfs_decrypt_page(file, page);
 354                 if (rc) {
 355                         ecryptfs_printk(KERN_ERR, "Error decrypting page; "
 356                                         "rc = [%d]\n", rc);
 357                         goto out;
 358                 }
 359         }
 360         SetPageUptodate(page);
 361 out:
 362         if (rc)
 363                 ClearPageUptodate(page);
 364         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 365                         page->index);
 366         unlock_page(page);
 367         return rc;
 368 }
 369
 370 /**
 371  * Called with lower inode mutex held.
 372  */
 373 static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
 374 {
 375         struct inode *inode = page->mapping->host;
 376         int end_byte_in_page;
 377         char *page_virt;
 378
 379         if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
 380                 goto out;
 381         end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
 382         if (to > end_byte_in_page)
 383                 end_byte_in_page = to;
 384         page_virt = kmap_atomic(page, KM_USER0);
 385         memset((page_virt + end_byte_in_page), 0,
 386                (PAGE_CACHE_SIZE - end_byte_in_page));
 387         kunmap_atomic(page_virt, KM_USER0);
 388         flush_dcache_page(page);
 389 out:
 390         return 0;
 391 }
 392
 393 static int ecryptfs_prepare_write(struct file *file, struct page *page,
 394                                   unsigned from, unsigned to)
 395 {
 396         int rc = 0;
 397
 398         if (from == 0 && to == PAGE_CACHE_SIZE)
 399                 goto out;       /* If we are writing a full page, it will be
 400                                    up to date. */
 401         if (!PageUptodate(page))
 402                 rc = ecryptfs_do_readpage(file, page, page->index);
 403 out:
 404         return rc;
 405 }
 406
 407 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
 408                                               struct inode *lower_inode,
 409                                               struct writeback_control *wbc)
 410 {
 411         int rc = 0;
 412
 413         rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
 414         if (rc) {
 415                 ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
 416                                 "rc = [%d]\n", rc);
 417                 goto out;
 418         }
 419         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 420         page_cache_release(lower_page);
 421 out:
 422         return rc;
 423 }
 424
 425 static void ecryptfs_release_lower_page(struct page *lower_page)
 426 {
 427         unlock_page(lower_page);
 428         page_cache_release(lower_page);
 429 }
 430
 431 /**
 432  * ecryptfs_write_inode_size_to_header
 433  *
 434  * Writes the lower file size to the first 8 bytes of the header.
 435  *
 436  * Returns zero on success; non-zero on error.
 437  */
 438 static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
 439                                                struct inode *lower_inode,
 440                                                struct inode *inode)
 441 {
 442         int rc = 0;
 443         struct page *header_page;
 444         char *header_virt;
 445         const struct address_space_operations *lower_a_ops;
 446         u64 file_size;
 447
 448         header_page = grab_cache_page(lower_inode->i_mapping, 0);
 449         if (!header_page) {
 450                 ecryptfs_printk(KERN_ERR, "grab_cache_page for "
 451                                 "lower_page_index 0 failed\n");
 452                 rc = -EINVAL;
 453                 goto out;
 454         }
 455         lower_a_ops = lower_inode->i_mapping->a_ops;
 456         rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
 457         file_size = (u64)i_size_read(inode);
 458         ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
 459         file_size = cpu_to_be64(file_size);
 460         header_virt = kmap_atomic(header_page, KM_USER0);
 461         memcpy(header_virt, &file_size, sizeof(u64));
 462         kunmap_atomic(header_virt, KM_USER0);
 463         flush_dcache_page(header_page);
 464         rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
 465         if (rc < 0)
 466                 ecryptfs_printk(KERN_ERR, "Error commiting header page "
 467                                 "write\n");
 468         ecryptfs_release_lower_page(header_page);
 469         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 470         mark_inode_dirty_sync(inode);
 471 out:
 472         return rc;
 473 }
 474
 475 static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
 476                                               struct inode *inode,
 477                                               struct dentry *ecryptfs_dentry,
 478                                               int lower_i_mutex_held)
 479 {
 480         ssize_t size;
 481         void *xattr_virt;
 482         struct dentry *lower_dentry;
 483         u64 file_size;
 484         int rc;
 485
 486         xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
 487         if (!xattr_virt) {
 488                 printk(KERN_ERR "Out of memory whilst attempting to write "
 489                        "inode size to xattr\n");
 490                 rc = -ENOMEM;
 491                 goto out;
 492         }
 493         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 494         if (!lower_dentry->d_inode->i_op->getxattr) {
 495                 printk(KERN_WARNING
 496                        "No support for setting xattr in lower filesystem\n");
 497                 rc = -ENOSYS;
 498                 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 499                 goto out;
 500         }
 501         if (!lower_i_mutex_held)
 502                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 503         size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
 504                                                      ECRYPTFS_XATTR_NAME,
 505                                                      xattr_virt,
 506                                                      PAGE_CACHE_SIZE);
 507         if (!lower_i_mutex_held)
 508                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 509         if (size < 0)
 510                 size = 8;
 511         file_size = (u64)i_size_read(inode);
 512         file_size = cpu_to_be64(file_size);
 513         memcpy(xattr_virt, &file_size, sizeof(u64));
 514         if (!lower_i_mutex_held)
 515                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 516         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
 517                                                    ECRYPTFS_XATTR_NAME,
 518                                                    xattr_virt, size, 0);
 519         if (!lower_i_mutex_held)
 520                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 521         if (rc)
 522                 printk(KERN_ERR "Error whilst attempting to write inode size "
 523                        "to lower file xattr; rc = [%d]\n", rc);
 524         kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 525 out:
 526         return rc;
 527 }
 528
 529 int
 530 ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
 531                                       struct inode *lower_inode,
 532                                       struct inode *inode,
 533                                       struct dentry *ecryptfs_dentry,
 534                                       int lower_i_mutex_held)
 535 {
 536         struct ecryptfs_crypt_stat *crypt_stat;
 537
 538         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 539         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 540                 return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
 541                                                           ecryptfs_dentry,
 542                                                           lower_i_mutex_held);
 543         else
 544                 return ecryptfs_write_inode_size_to_header(lower_file,
 545                                                            lower_inode,
 546                                                            inode);
 547 }
 548
 549 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 550                             struct file *lower_file,
 551                             unsigned long lower_page_index, int byte_offset,
 552                             int region_bytes)
 553 {
 554         int rc = 0;
 555
 556         *lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
 557         if (!(*lower_page)) {
 558                 rc = -EINVAL;
 559                 ecryptfs_printk(KERN_ERR, "Error attempting to grab "
 560                                 "lower page with index [0x%.16x]\n",
 561                                 lower_page_index);
 562                 goto out;
 563         }
 564         rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
 565                                                           (*lower_page),
 566                                                           byte_offset,
 567                                                           region_bytes);
 568         if (rc) {
 569                 ecryptfs_printk(KERN_ERR, "prepare_write for "
 570                                 "lower_page_index = [0x%.16x] failed; rc = "
 571                                 "[%d]\n", lower_page_index, rc);
 572         }
 573 out:
 574         if (rc && (*lower_page)) {
 575                 ecryptfs_release_lower_page(*lower_page);
 576                 (*lower_page) = NULL;
 577         }
 578         return rc;
 579 }
 580
 581 /**
 582  * ecryptfs_commit_lower_page
 583  *
 584  * Returns zero on success; non-zero on error
 585  */
 586 int
 587 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
 588                            struct file *lower_file, int byte_offset,
 589                            int region_size)
 590 {
 591         int rc = 0;
 592
 593         rc = lower_inode->i_mapping->a_ops->commit_write(
 594                 lower_file, lower_page, byte_offset, region_size);
 595         if (rc < 0) {
 596                 ecryptfs_printk(KERN_ERR,
 597                                 "Error committing write; rc = [%d]\n", rc);
 598         } else
 599                 rc = 0;
 600         ecryptfs_release_lower_page(lower_page);
 601         return rc;
 602 }
 603
 604 /**
 605  * ecryptfs_copy_page_to_lower
 606  *
 607  * Used for plaintext pass-through; no page index interpolation
 608  * required.
 609  */
 610 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
 611                                 struct file *lower_file)
 612 {
 613         int rc = 0;
 614         struct page *lower_page;
 615
 616         rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
 617                                      page->index, 0, PAGE_CACHE_SIZE);
 618         if (rc) {
 619                 ecryptfs_printk(KERN_ERR, "Error attempting to get page "
 620                                 "at index [0x%.16x]\n", page->index);
 621                 goto out;
 622         }
 623         /* TODO: aops */
 624         memcpy((char *)page_address(lower_page), page_address(page),
 625                PAGE_CACHE_SIZE);
 626         rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
 627                                         0, PAGE_CACHE_SIZE);
 628         if (rc)
 629                 ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
 630                                 "at index [0x%.16x]\n", page->index);
 631 out:
 632         return rc;
 633 }
 634
 635 struct kmem_cache *ecryptfs_xattr_cache;
 636
 637 /**
 638  * ecryptfs_commit_write
 639  * @file: The eCryptfs file object
 640  * @page: The eCryptfs page
 641  * @from: Ignored (we rotate the page IV on each write)
 642  * @to: Ignored
 643  *
 644  * This is where we encrypt the data and pass the encrypted data to
 645  * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 646  * entire underlying packets.
 647  */
 648 static int ecryptfs_commit_write(struct file *file, struct page *page,
 649                                  unsigned from, unsigned to)
 650 {
 651         struct ecryptfs_page_crypt_context ctx;
 652         loff_t pos;
 653         struct inode *inode;
 654         struct inode *lower_inode;
 655         struct file *lower_file;
 656         struct ecryptfs_crypt_stat *crypt_stat;
 657         int rc;
 658
 659         inode = page->mapping->host;
 660         lower_inode = ecryptfs_inode_to_lower(inode);
 661         lower_file = ecryptfs_file_to_lower(file);
 662         mutex_lock(&lower_inode->i_mutex);
 663         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 664                                 ->crypt_stat;
 665         if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
 666                 ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
 667                         "crypt_stat at memory location [%p]\n", crypt_stat);
 668                 crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
 669         } else
 670                 ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
 671         ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
 672                         "(page w/ index = [0x%.16x], to = [%d])\n", page->index,
 673                         to);
 674         rc = fill_zeros_to_end_of_page(page, to);
 675         if (rc) {
 676                 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
 677                                 "zeros in page with index = [0x%.16x]\n",
 678                                 page->index);
 679                 goto out;
 680         }
 681         ctx.page = page;
 682         ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
 683         ctx.param.lower_file = lower_file;
 684         rc = ecryptfs_encrypt_page(&ctx);
 685         if (rc) {
 686                 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
 687                                 "index [0x%.16x])\n", page->index);
 688                 goto out;
 689         }
 690         inode->i_blocks = lower_inode->i_blocks;
 691         pos = (page->index << PAGE_CACHE_SHIFT) + to;
 692         if (pos > i_size_read(inode)) {
 693                 i_size_write(inode, pos);
 694                 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
 695                                 "[0x%.16x]\n", i_size_read(inode));
 696         }
 697         rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
 698                                                    inode, file->f_dentry,
 699                                                    ECRYPTFS_LOWER_I_MUTEX_HELD);
 700         if (rc)
 701                 printk(KERN_ERR "Error writing inode size to metadata; "
 702                        "rc = [%d]\n", rc);
 703         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 704         mark_inode_dirty_sync(inode);
 705 out:
 706         if (rc < 0)
 707                 ClearPageUptodate(page);
 708         else
 709                 SetPageUptodate(page);
 710         mutex_unlock(&lower_inode->i_mutex);
 711         return rc;
 712 }
 713
 714 /**
 715  * write_zeros
 716  * @file: The ecryptfs file
 717  * @index: The index in which we are writing
 718  * @start: The position after the last block of data
 719  * @num_zeros: The number of zeros to write
 720  *
 721  * Write a specified number of zero's to a page.
 722  *
 723  * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
 724  */
 725 static
 726 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
 727 {
 728         int rc = 0;
 729         struct page *tmp_page;
 730         char *tmp_page_virt;
 731
 732         tmp_page = ecryptfs_get1page(file, index);
 733         if (IS_ERR(tmp_page)) {
 734                 ecryptfs_printk(KERN_ERR, "Error getting page at index "
 735                                 "[0x%.16x]\n", index);
 736                 rc = PTR_ERR(tmp_page);
 737                 goto out;
 738         }
 739         rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
 740         if (rc) {
 741                 ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
 742                                 "to remainder of page at index [0x%.16x]\n",
 743                                 index);
 744                 page_cache_release(tmp_page);
 745                 goto out;
 746         }
 747         tmp_page_virt = kmap_atomic(tmp_page, KM_USER0);
 748         memset(((char *)tmp_page_virt + start), 0, num_zeros);
 749         kunmap_atomic(tmp_page_virt, KM_USER0);
 750         flush_dcache_page(tmp_page);
 751         rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
 752         if (rc < 0) {
 753                 ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
 754                                 "to remainder of page at index [0x%.16x]\n",
 755                                 index);
 756                 page_cache_release(tmp_page);
 757                 goto out;
 758         }
 759         rc = 0;
 760         page_cache_release(tmp_page);
 761 out:
 762         return rc;
 763 }
 764
 765 static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
 766 {
 767         int rc = 0;
 768         struct inode *inode;
 769         struct inode *lower_inode;
 770
 771         inode = (struct inode *)mapping->host;
 772         lower_inode = ecryptfs_inode_to_lower(inode);
 773         if (lower_inode->i_mapping->a_ops->bmap)
 774                 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
 775                                                          block);
 776         return rc;
 777 }
 778
 779 static void ecryptfs_sync_page(struct page *page)
 780 {
 781         struct inode *inode;
 782         struct inode *lower_inode;
 783         struct page *lower_page;
 784
 785         inode = page->mapping->host;
 786         lower_inode = ecryptfs_inode_to_lower(inode);
 787         /* NOTE: Recently swapped with grab_cache_page(), since
 788          * sync_page() just makes sure that pending I/O gets done. */
 789         lower_page = find_lock_page(lower_inode->i_mapping, page->index);
 790         if (!lower_page) {
 791                 ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
 792                 return;
 793         }
 794         lower_page->mapping->a_ops->sync_page(lower_page);
 795         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 796                         lower_page->index);
 797         unlock_page(lower_page);
 798         page_cache_release(lower_page);
 799 }
 800
 801 struct address_space_operations ecryptfs_aops = {
 802         .writepage = ecryptfs_writepage,
 803         .readpage = ecryptfs_readpage,
 804         .prepare_write = ecryptfs_prepare_write,
 805         .commit_write = ecryptfs_commit_write,
 806         .bmap = ecryptfs_bmap,
 807         .sync_page = ecryptfs_sync_page,
 808 };