SAFE public projects git trees. - safe/jmp/linux-2.6/blob - 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         kunmap_atomic(page_data, KM_USER0);
 242         rc = 0;
 243 out:
 244         if (likely(lower_page))
 245                 page_cache_release(lower_page);
 246         if (rc == 0)
 247                 SetPageUptodate(page);
 248         else
 249                 ClearPageUptodate(page);
 250         return rc;
 251 }
 252 /**
 253  *   Header Extent:
 254  *     Octets 0-7:        Unencrypted file size (big-endian)
 255  *     Octets 8-15:       eCryptfs special marker
 256  *     Octets 16-19:      Flags
 257  *      Octet 16:         File format version number (between 0 and 255)
 258  *      Octets 17-18:     Reserved
 259  *      Octet 19:         Bit 1 (lsb): Reserved
 260  *                        Bit 2: Encrypted?
 261  *                        Bits 3-8: Reserved
 262  *     Octets 20-23:      Header extent size (big-endian)
 263  *     Octets 24-25:      Number of header extents at front of file
 264  *                        (big-endian)
 265  *     Octet  26:         Begin RFC 2440 authentication token packet set
 266  */
 267 static void set_header_info(char *page_virt,
 268                             struct ecryptfs_crypt_stat *crypt_stat)
 269 {
 270         size_t written;
 271         int save_num_header_extents_at_front =
 272                 crypt_stat->num_header_extents_at_front;
 273
 274         crypt_stat->num_header_extents_at_front = 1;
 275         ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
 276         crypt_stat->num_header_extents_at_front =
 277                 save_num_header_extents_at_front;
 278 }
 279
 280 /**
 281  * ecryptfs_readpage
 282  * @file: This is an ecryptfs file
 283  * @page: ecryptfs associated page to stick the read data into
 284  *
 285  * Read in a page, decrypting if necessary.
 286  *
 287  * Returns zero on success; non-zero on error.
 288  */
 289 static int ecryptfs_readpage(struct file *file, struct page *page)
 290 {
 291         int rc = 0;
 292         struct ecryptfs_crypt_stat *crypt_stat;
 293
 294         BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
 295         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 296                         ->crypt_stat;
 297         if (!crypt_stat
 298             || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)
 299             || ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
 300                 ecryptfs_printk(KERN_DEBUG,
 301                                 "Passing through unencrypted page\n");
 302                 rc = ecryptfs_do_readpage(file, page, page->index);
 303                 if (rc) {
 304                         ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
 305                                         "[%d]\n", rc);
 306                         goto out;
 307                 }
 308         } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
 309                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
 310                         int num_pages_in_header_region =
 311                                 (crypt_stat->header_extent_size
 312                                  / PAGE_CACHE_SIZE);
 313
 314                         if (page->index < num_pages_in_header_region) {
 315                                 char *page_virt;
 316
 317                                 page_virt = kmap_atomic(page, KM_USER0);
 318                                 memset(page_virt, 0, PAGE_CACHE_SIZE);
 319                                 if (page->index == 0) {
 320                                         rc = ecryptfs_read_xattr_region(
 321                                                 page_virt, file->f_path.dentry);
 322                                         set_header_info(page_virt, crypt_stat);
 323                                 }
 324                                 kunmap_atomic(page_virt, KM_USER0);
 325                                 if (rc) {
 326                                         printk(KERN_ERR "Error reading xattr "
 327                                                "region\n");
 328                                         goto out;
 329                                 }
 330                         } else {
 331                                 rc = ecryptfs_do_readpage(
 332                                         file, page,
 333                                         (page->index
 334                                          - num_pages_in_header_region));
 335                                 if (rc) {
 336                                         printk(KERN_ERR "Error reading page; "
 337                                                "rc = [%d]\n", rc);
 338                                         goto out;
 339                                 }
 340                         }
 341                 } else {
 342                         rc = ecryptfs_do_readpage(file, page, page->index);
 343                         if (rc) {
 344                                 printk(KERN_ERR "Error reading page; rc = "
 345                                        "[%d]\n", rc);
 346                                 goto out;
 347                         }
 348                 }
 349         } else {
 350                 rc = ecryptfs_decrypt_page(file, page);
 351                 if (rc) {
 352                         ecryptfs_printk(KERN_ERR, "Error decrypting page; "
 353                                         "rc = [%d]\n", rc);
 354                         goto out;
 355                 }
 356         }
 357         SetPageUptodate(page);
 358 out:
 359         if (rc)
 360                 ClearPageUptodate(page);
 361         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 362                         page->index);
 363         unlock_page(page);
 364         return rc;
 365 }
 366
 367 /**
 368  * Called with lower inode mutex held.
 369  */
 370 static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
 371 {
 372         struct inode *inode = page->mapping->host;
 373         int end_byte_in_page;
 374         char *page_virt;
 375
 376         if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
 377                 goto out;
 378         end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
 379         if (to > end_byte_in_page)
 380                 end_byte_in_page = to;
 381         page_virt = kmap_atomic(page, KM_USER0);
 382         memset((page_virt + end_byte_in_page), 0,
 383                (PAGE_CACHE_SIZE - end_byte_in_page));
 384         kunmap_atomic(page_virt, KM_USER0);
 385 out:
 386         return 0;
 387 }
 388
 389 static int ecryptfs_prepare_write(struct file *file, struct page *page,
 390                                   unsigned from, unsigned to)
 391 {
 392         int rc = 0;
 393
 394         if (from == 0 && to == PAGE_CACHE_SIZE)
 395                 goto out;       /* If we are writing a full page, it will be
 396                                    up to date. */
 397         if (!PageUptodate(page))
 398                 rc = ecryptfs_do_readpage(file, page, page->index);
 399 out:
 400         return rc;
 401 }
 402
 403 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
 404                                               struct inode *lower_inode,
 405                                               struct writeback_control *wbc)
 406 {
 407         int rc = 0;
 408
 409         rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
 410         if (rc) {
 411                 ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
 412                                 "rc = [%d]\n", rc);
 413                 goto out;
 414         }
 415         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 416         page_cache_release(lower_page);
 417 out:
 418         return rc;
 419 }
 420
 421 static void ecryptfs_release_lower_page(struct page *lower_page)
 422 {
 423         unlock_page(lower_page);
 424         page_cache_release(lower_page);
 425 }
 426
 427 /**
 428  * ecryptfs_write_inode_size_to_header
 429  *
 430  * Writes the lower file size to the first 8 bytes of the header.
 431  *
 432  * Returns zero on success; non-zero on error.
 433  */
 434 static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
 435                                                struct inode *lower_inode,
 436                                                struct inode *inode)
 437 {
 438         int rc = 0;
 439         struct page *header_page;
 440         char *header_virt;
 441         const struct address_space_operations *lower_a_ops;
 442         u64 file_size;
 443
 444         header_page = grab_cache_page(lower_inode->i_mapping, 0);
 445         if (!header_page) {
 446                 ecryptfs_printk(KERN_ERR, "grab_cache_page for "
 447                                 "lower_page_index 0 failed\n");
 448                 rc = -EINVAL;
 449                 goto out;
 450         }
 451         lower_a_ops = lower_inode->i_mapping->a_ops;
 452         rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
 453         file_size = (u64)i_size_read(inode);
 454         ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
 455         file_size = cpu_to_be64(file_size);
 456         header_virt = kmap_atomic(header_page, KM_USER0);
 457         memcpy(header_virt, &file_size, sizeof(u64));
 458         kunmap_atomic(header_virt, KM_USER0);
 459         rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
 460         if (rc < 0)
 461                 ecryptfs_printk(KERN_ERR, "Error commiting header page "
 462                                 "write\n");
 463         ecryptfs_release_lower_page(header_page);
 464         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 465         mark_inode_dirty_sync(inode);
 466 out:
 467         return rc;
 468 }
 469
 470 static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
 471                                               struct inode *inode,
 472                                               struct dentry *ecryptfs_dentry,
 473                                               int lower_i_mutex_held)
 474 {
 475         ssize_t size;
 476         void *xattr_virt;
 477         struct dentry *lower_dentry;
 478         u64 file_size;
 479         int rc;
 480
 481         xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
 482         if (!xattr_virt) {
 483                 printk(KERN_ERR "Out of memory whilst attempting to write "
 484                        "inode size to xattr\n");
 485                 rc = -ENOMEM;
 486                 goto out;
 487         }
 488         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 489         if (!lower_dentry->d_inode->i_op->getxattr) {
 490                 printk(KERN_WARNING
 491                        "No support for setting xattr in lower filesystem\n");
 492                 rc = -ENOSYS;
 493                 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 494                 goto out;
 495         }
 496         if (!lower_i_mutex_held)
 497                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 498         size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
 499                                                      ECRYPTFS_XATTR_NAME,
 500                                                      xattr_virt,
 501                                                      PAGE_CACHE_SIZE);
 502         if (!lower_i_mutex_held)
 503                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 504         if (size < 0)
 505                 size = 8;
 506         file_size = (u64)i_size_read(inode);
 507         file_size = cpu_to_be64(file_size);
 508         memcpy(xattr_virt, &file_size, sizeof(u64));
 509         if (!lower_i_mutex_held)
 510                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 511         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
 512                                                    ECRYPTFS_XATTR_NAME,
 513                                                    xattr_virt, size, 0);
 514         if (!lower_i_mutex_held)
 515                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 516         if (rc)
 517                 printk(KERN_ERR "Error whilst attempting to write inode size "
 518                        "to lower file xattr; rc = [%d]\n", rc);
 519         kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 520 out:
 521         return rc;
 522 }
 523
 524 int
 525 ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
 526                                       struct inode *lower_inode,
 527                                       struct inode *inode,
 528                                       struct dentry *ecryptfs_dentry,
 529                                       int lower_i_mutex_held)
 530 {
 531         struct ecryptfs_crypt_stat *crypt_stat;
 532
 533         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 534         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 535                 return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
 536                                                           ecryptfs_dentry,
 537                                                           lower_i_mutex_held);
 538         else
 539                 return ecryptfs_write_inode_size_to_header(lower_file,
 540                                                            lower_inode,
 541                                                            inode);
 542 }
 543
 544 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 545                             struct file *lower_file,
 546                             unsigned long lower_page_index, int byte_offset,
 547                             int region_bytes)
 548 {
 549         int rc = 0;
 550
 551         *lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
 552         if (!(*lower_page)) {
 553                 rc = -EINVAL;
 554                 ecryptfs_printk(KERN_ERR, "Error attempting to grab "
 555                                 "lower page with index [0x%.16x]\n",
 556                                 lower_page_index);
 557                 goto out;
 558         }
 559         rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
 560                                                           (*lower_page),
 561                                                           byte_offset,
 562                                                           region_bytes);
 563         if (rc) {
 564                 ecryptfs_printk(KERN_ERR, "prepare_write for "
 565                                 "lower_page_index = [0x%.16x] failed; rc = "
 566                                 "[%d]\n", lower_page_index, rc);
 567         }
 568 out:
 569         if (rc && (*lower_page)) {
 570                 ecryptfs_release_lower_page(*lower_page);
 571                 (*lower_page) = NULL;
 572         }
 573         return rc;
 574 }
 575
 576 /**
 577  * ecryptfs_commit_lower_page
 578  *
 579  * Returns zero on success; non-zero on error
 580  */
 581 int
 582 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
 583                            struct file *lower_file, int byte_offset,
 584                            int region_size)
 585 {
 586         int rc = 0;
 587
 588         rc = lower_inode->i_mapping->a_ops->commit_write(
 589                 lower_file, lower_page, byte_offset, region_size);
 590         if (rc < 0) {
 591                 ecryptfs_printk(KERN_ERR,
 592                                 "Error committing write; rc = [%d]\n", rc);
 593         } else
 594                 rc = 0;
 595         ecryptfs_release_lower_page(lower_page);
 596         return rc;
 597 }
 598
 599 /**
 600  * ecryptfs_copy_page_to_lower
 601  *
 602  * Used for plaintext pass-through; no page index interpolation
 603  * required.
 604  */
 605 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
 606                                 struct file *lower_file)
 607 {
 608         int rc = 0;
 609         struct page *lower_page;
 610
 611         rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
 612                                      page->index, 0, PAGE_CACHE_SIZE);
 613         if (rc) {
 614                 ecryptfs_printk(KERN_ERR, "Error attempting to get page "
 615                                 "at index [0x%.16x]\n", page->index);
 616                 goto out;
 617         }
 618         /* TODO: aops */
 619         memcpy((char *)page_address(lower_page), page_address(page),
 620                PAGE_CACHE_SIZE);
 621         rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
 622                                         0, PAGE_CACHE_SIZE);
 623         if (rc)
 624                 ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
 625                                 "at index [0x%.16x]\n", page->index);
 626 out:
 627         return rc;
 628 }
 629
 630 struct kmem_cache *ecryptfs_xattr_cache;
 631
 632 /**
 633  * ecryptfs_commit_write
 634  * @file: The eCryptfs file object
 635  * @page: The eCryptfs page
 636  * @from: Ignored (we rotate the page IV on each write)
 637  * @to: Ignored
 638  *
 639  * This is where we encrypt the data and pass the encrypted data to
 640  * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 641  * entire underlying packets.
 642  */
 643 static int ecryptfs_commit_write(struct file *file, struct page *page,
 644                                  unsigned from, unsigned to)
 645 {
 646         struct ecryptfs_page_crypt_context ctx;
 647         loff_t pos;
 648         struct inode *inode;
 649         struct inode *lower_inode;
 650         struct file *lower_file;
 651         struct ecryptfs_crypt_stat *crypt_stat;
 652         int rc;
 653
 654         inode = page->mapping->host;
 655         lower_inode = ecryptfs_inode_to_lower(inode);
 656         lower_file = ecryptfs_file_to_lower(file);
 657         mutex_lock(&lower_inode->i_mutex);
 658         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 659                                 ->crypt_stat;
 660         if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
 661                 ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
 662                         "crypt_stat at memory location [%p]\n", crypt_stat);
 663                 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE);
 664         } else
 665                 ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
 666         ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
 667                         "(page w/ index = [0x%.16x], to = [%d])\n", page->index,
 668                         to);
 669         rc = fill_zeros_to_end_of_page(page, to);
 670         if (rc) {
 671                 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
 672                                 "zeros in page with index = [0x%.16x]\n",
 673                                 page->index);
 674                 goto out;
 675         }
 676         ctx.page = page;
 677         ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
 678         ctx.param.lower_file = lower_file;
 679         rc = ecryptfs_encrypt_page(&ctx);
 680         if (rc) {
 681                 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
 682                                 "index [0x%.16x])\n", page->index);
 683                 goto out;
 684         }
 685         inode->i_blocks = lower_inode->i_blocks;
 686         pos = (page->index << PAGE_CACHE_SHIFT) + to;
 687         if (pos > i_size_read(inode)) {
 688                 i_size_write(inode, pos);
 689                 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
 690                                 "[0x%.16x]\n", i_size_read(inode));
 691         }
 692         rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
 693                                                    inode, file->f_dentry,
 694                                                    ECRYPTFS_LOWER_I_MUTEX_HELD);
 695         if (rc)
 696                 printk(KERN_ERR "Error writing inode size to metadata; "
 697                        "rc = [%d]\n", rc);
 698         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 699         mark_inode_dirty_sync(inode);
 700 out:
 701         if (rc < 0)
 702                 ClearPageUptodate(page);
 703         else
 704                 SetPageUptodate(page);
 705         mutex_unlock(&lower_inode->i_mutex);
 706         return rc;
 707 }
 708
 709 /**
 710  * write_zeros
 711  * @file: The ecryptfs file
 712  * @index: The index in which we are writing
 713  * @start: The position after the last block of data
 714  * @num_zeros: The number of zeros to write
 715  *
 716  * Write a specified number of zero's to a page.
 717  *
 718  * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
 719  */
 720 static
 721 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
 722 {
 723         int rc = 0;
 724         struct page *tmp_page;
 725         char *tmp_page_virt;
 726
 727         tmp_page = ecryptfs_get1page(file, index);
 728         if (IS_ERR(tmp_page)) {
 729                 ecryptfs_printk(KERN_ERR, "Error getting page at index "
 730                                 "[0x%.16x]\n", index);
 731                 rc = PTR_ERR(tmp_page);
 732                 goto out;
 733         }
 734         rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
 735         if (rc) {
 736                 ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
 737                                 "to remainder of page at index [0x%.16x]\n",
 738                                 index);
 739                 page_cache_release(tmp_page);
 740                 goto out;
 741         }
 742         tmp_page_virt = kmap_atomic(tmp_page, KM_USER0);
 743         memset(((char *)tmp_page_virt + start), 0, num_zeros);
 744         kunmap_atomic(tmp_page_virt, KM_USER0);
 745         rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
 746         if (rc < 0) {
 747                 ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
 748                                 "to remainder of page at index [0x%.16x]\n",
 749                                 index);
 750                 page_cache_release(tmp_page);
 751                 goto out;
 752         }
 753         rc = 0;
 754         page_cache_release(tmp_page);
 755 out:
 756         return rc;
 757 }
 758
 759 static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
 760 {
 761         int rc = 0;
 762         struct inode *inode;
 763         struct inode *lower_inode;
 764
 765         inode = (struct inode *)mapping->host;
 766         lower_inode = ecryptfs_inode_to_lower(inode);
 767         if (lower_inode->i_mapping->a_ops->bmap)
 768                 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
 769                                                          block);
 770         return rc;
 771 }
 772
 773 static void ecryptfs_sync_page(struct page *page)
 774 {
 775         struct inode *inode;
 776         struct inode *lower_inode;
 777         struct page *lower_page;
 778
 779         inode = page->mapping->host;
 780         lower_inode = ecryptfs_inode_to_lower(inode);
 781         /* NOTE: Recently swapped with grab_cache_page(), since
 782          * sync_page() just makes sure that pending I/O gets done. */
 783         lower_page = find_lock_page(lower_inode->i_mapping, page->index);
 784         if (!lower_page) {
 785                 ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
 786                 return;
 787         }
 788         lower_page->mapping->a_ops->sync_page(lower_page);
 789         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 790                         lower_page->index);
 791         unlock_page(lower_page);
 792         page_cache_release(lower_page);
 793 }
 794
 795 struct address_space_operations ecryptfs_aops = {
 796         .writepage = ecryptfs_writepage,
 797         .readpage = ecryptfs_readpage,
 798         .prepare_write = ecryptfs_prepare_write,
 799         .commit_write = ecryptfs_commit_write,
 800         .bmap = ecryptfs_bmap,
 801         .sync_page = ecryptfs_sync_page,
 802 };