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 = (char *)kmap(page);
 238         if (!page_data) {
 239                 rc = -ENOMEM;
 240                 ecryptfs_printk(KERN_ERR, "Error mapping page\n");
 241                 goto out;
 242         }
 243         lower_page_data = (char *)kmap(lower_page);
 244         if (!lower_page_data) {
 245                 rc = -ENOMEM;
 246                 ecryptfs_printk(KERN_ERR, "Error mapping page\n");
 247                 kunmap(page);
 248                 goto out;
 249         }
 250         memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
 251         kunmap(lower_page);
 252         kunmap(page);
 253         rc = 0;
 254 out:
 255         if (likely(lower_page))
 256                 page_cache_release(lower_page);
 257         if (rc == 0)
 258                 SetPageUptodate(page);
 259         else
 260                 ClearPageUptodate(page);
 261         return rc;
 262 }
 263 /**
 264  *   Header Extent:
 265  *     Octets 0-7:        Unencrypted file size (big-endian)
 266  *     Octets 8-15:       eCryptfs special marker
 267  *     Octets 16-19:      Flags
 268  *      Octet 16:         File format version number (between 0 and 255)
 269  *      Octets 17-18:     Reserved
 270  *      Octet 19:         Bit 1 (lsb): Reserved
 271  *                        Bit 2: Encrypted?
 272  *                        Bits 3-8: Reserved
 273  *     Octets 20-23:      Header extent size (big-endian)
 274  *     Octets 24-25:      Number of header extents at front of file
 275  *                        (big-endian)
 276  *     Octet  26:         Begin RFC 2440 authentication token packet set
 277  */
 278 static void set_header_info(char *page_virt,
 279                             struct ecryptfs_crypt_stat *crypt_stat)
 280 {
 281         size_t written;
 282         int save_num_header_extents_at_front =
 283                 crypt_stat->num_header_extents_at_front;
 284
 285         crypt_stat->num_header_extents_at_front = 1;
 286         ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
 287         crypt_stat->num_header_extents_at_front =
 288                 save_num_header_extents_at_front;
 289 }
 290
 291 /**
 292  * ecryptfs_readpage
 293  * @file: This is an ecryptfs file
 294  * @page: ecryptfs associated page to stick the read data into
 295  *
 296  * Read in a page, decrypting if necessary.
 297  *
 298  * Returns zero on success; non-zero on error.
 299  */
 300 static int ecryptfs_readpage(struct file *file, struct page *page)
 301 {
 302         int rc = 0;
 303         struct ecryptfs_crypt_stat *crypt_stat;
 304
 305         BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
 306         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 307                         ->crypt_stat;
 308         if (!crypt_stat
 309             || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)
 310             || ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
 311                 ecryptfs_printk(KERN_DEBUG,
 312                                 "Passing through unencrypted page\n");
 313                 rc = ecryptfs_do_readpage(file, page, page->index);
 314                 if (rc) {
 315                         ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
 316                                         "[%d]\n", rc);
 317                         goto out;
 318                 }
 319         } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
 320                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
 321                         int num_pages_in_header_region =
 322                                 (crypt_stat->header_extent_size
 323                                  / PAGE_CACHE_SIZE);
 324
 325                         if (page->index < num_pages_in_header_region) {
 326                                 char *page_virt;
 327
 328                                 page_virt = (char *)kmap(page);
 329                                 if (!page_virt) {
 330                                         rc = -ENOMEM;
 331                                         printk(KERN_ERR "Error mapping page\n");
 332                                         goto out;
 333                                 }
 334                                 memset(page_virt, 0, PAGE_CACHE_SIZE);
 335                                 if (page->index == 0) {
 336                                         rc = ecryptfs_read_xattr_region(
 337                                                 page_virt, file->f_path.dentry);
 338                                         set_header_info(page_virt, crypt_stat);
 339                                 }
 340                                 kunmap(page);
 341                                 if (rc) {
 342                                         printk(KERN_ERR "Error reading xattr "
 343                                                "region\n");
 344                                         goto out;
 345                                 }
 346                         } else {
 347                                 rc = ecryptfs_do_readpage(
 348                                         file, page,
 349                                         (page->index
 350                                          - num_pages_in_header_region));
 351                                 if (rc) {
 352                                         printk(KERN_ERR "Error reading page; "
 353                                                "rc = [%d]\n", rc);
 354                                         goto out;
 355                                 }
 356                         }
 357                 } else {
 358                         rc = ecryptfs_do_readpage(file, page, page->index);
 359                         if (rc) {
 360                                 printk(KERN_ERR "Error reading page; rc = "
 361                                        "[%d]\n", rc);
 362                                 goto out;
 363                         }
 364                 }
 365         } else {
 366                 rc = ecryptfs_decrypt_page(file, page);
 367                 if (rc) {
 368                         ecryptfs_printk(KERN_ERR, "Error decrypting page; "
 369                                         "rc = [%d]\n", rc);
 370                         goto out;
 371                 }
 372         }
 373         SetPageUptodate(page);
 374 out:
 375         if (rc)
 376                 ClearPageUptodate(page);
 377         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 378                         page->index);
 379         unlock_page(page);
 380         return rc;
 381 }
 382
 383 /**
 384  * Called with lower inode mutex held.
 385  */
 386 static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
 387 {
 388         struct inode *inode = page->mapping->host;
 389         int end_byte_in_page;
 390         int rc = 0;
 391         char *page_virt;
 392
 393         if ((i_size_read(inode) / PAGE_CACHE_SIZE) == page->index) {
 394                 end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
 395                 if (to > end_byte_in_page)
 396                         end_byte_in_page = to;
 397                 page_virt = kmap(page);
 398                 if (!page_virt) {
 399                         rc = -ENOMEM;
 400                         ecryptfs_printk(KERN_WARNING,
 401                                         "Could not map page\n");
 402                         goto out;
 403                 }
 404                 memset((page_virt + end_byte_in_page), 0,
 405                        (PAGE_CACHE_SIZE - end_byte_in_page));
 406                 kunmap(page);
 407         }
 408 out:
 409         return rc;
 410 }
 411
 412 static int ecryptfs_prepare_write(struct file *file, struct page *page,
 413                                   unsigned from, unsigned to)
 414 {
 415         int rc = 0;
 416
 417         kmap(page);
 418         if (from == 0 && to == PAGE_CACHE_SIZE)
 419                 goto out;       /* If we are writing a full page, it will be
 420                                    up to date. */
 421         if (!PageUptodate(page))
 422                 rc = ecryptfs_do_readpage(file, page, page->index);
 423 out:
 424         return rc;
 425 }
 426
 427 int ecryptfs_grab_and_map_lower_page(struct page **lower_page,
 428                                      char **lower_virt,
 429                                      struct inode *lower_inode,
 430                                      unsigned long lower_page_index)
 431 {
 432         int rc = 0;
 433
 434         (*lower_page) = grab_cache_page(lower_inode->i_mapping,
 435                                         lower_page_index);
 436         if (!(*lower_page)) {
 437                 ecryptfs_printk(KERN_ERR, "grab_cache_page for "
 438                                 "lower_page_index = [0x%.16x] failed\n",
 439                                 lower_page_index);
 440                 rc = -EINVAL;
 441                 goto out;
 442         }
 443         if (lower_virt)
 444                 (*lower_virt) = kmap((*lower_page));
 445         else
 446                 kmap((*lower_page));
 447 out:
 448         return rc;
 449 }
 450
 451 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
 452                                               struct inode *lower_inode,
 453                                               struct writeback_control *wbc)
 454 {
 455         int rc = 0;
 456
 457         rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
 458         if (rc) {
 459                 ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
 460                                 "rc = [%d]\n", rc);
 461                 goto out;
 462         }
 463         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 464         page_cache_release(lower_page);
 465 out:
 466         return rc;
 467 }
 468
 469 static void ecryptfs_unmap_and_release_lower_page(struct page *lower_page)
 470 {
 471         kunmap(lower_page);
 472         ecryptfs_printk(KERN_DEBUG, "Unlocking lower page with index = "
 473                         "[0x%.16x]\n", lower_page->index);
 474         unlock_page(lower_page);
 475         page_cache_release(lower_page);
 476 }
 477
 478 /**
 479  * ecryptfs_write_inode_size_to_header
 480  *
 481  * Writes the lower file size to the first 8 bytes of the header.
 482  *
 483  * Returns zero on success; non-zero on error.
 484  */
 485 static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
 486                                                struct inode *lower_inode,
 487                                                struct inode *inode)
 488 {
 489         int rc = 0;
 490         struct page *header_page;
 491         char *header_virt;
 492         const struct address_space_operations *lower_a_ops;
 493         u64 file_size;
 494
 495         rc = ecryptfs_grab_and_map_lower_page(&header_page, &header_virt,
 496                                               lower_inode, 0);
 497         if (rc) {
 498                 ecryptfs_printk(KERN_ERR, "grab_cache_page for header page "
 499                                 "failed\n");
 500                 goto out;
 501         }
 502         lower_a_ops = lower_inode->i_mapping->a_ops;
 503         rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
 504         file_size = (u64)i_size_read(inode);
 505         ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
 506         file_size = cpu_to_be64(file_size);
 507         memcpy(header_virt, &file_size, sizeof(u64));
 508         rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
 509         if (rc < 0)
 510                 ecryptfs_printk(KERN_ERR, "Error commiting header page "
 511                                 "write\n");
 512         ecryptfs_unmap_and_release_lower_page(header_page);
 513         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 514         mark_inode_dirty_sync(inode);
 515 out:
 516         return rc;
 517 }
 518
 519 static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
 520                                               struct inode *inode,
 521                                               struct dentry *ecryptfs_dentry,
 522                                               int lower_i_mutex_held)
 523 {
 524         ssize_t size;
 525         void *xattr_virt;
 526         struct dentry *lower_dentry;
 527         u64 file_size;
 528         int rc;
 529
 530         xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
 531         if (!xattr_virt) {
 532                 printk(KERN_ERR "Out of memory whilst attempting to write "
 533                        "inode size to xattr\n");
 534                 rc = -ENOMEM;
 535                 goto out;
 536         }
 537         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 538         if (!lower_dentry->d_inode->i_op->getxattr) {
 539                 printk(KERN_WARNING
 540                        "No support for setting xattr in lower filesystem\n");
 541                 rc = -ENOSYS;
 542                 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 543                 goto out;
 544         }
 545         if (!lower_i_mutex_held)
 546                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 547         size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
 548                                                      ECRYPTFS_XATTR_NAME,
 549                                                      xattr_virt,
 550                                                      PAGE_CACHE_SIZE);
 551         if (!lower_i_mutex_held)
 552                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 553         if (size < 0)
 554                 size = 8;
 555         file_size = (u64)i_size_read(inode);
 556         file_size = cpu_to_be64(file_size);
 557         memcpy(xattr_virt, &file_size, sizeof(u64));
 558         if (!lower_i_mutex_held)
 559                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 560         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
 561                                                    ECRYPTFS_XATTR_NAME,
 562                                                    xattr_virt, size, 0);
 563         if (!lower_i_mutex_held)
 564                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 565         if (rc)
 566                 printk(KERN_ERR "Error whilst attempting to write inode size "
 567                        "to lower file xattr; rc = [%d]\n", rc);
 568         kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 569 out:
 570         return rc;
 571 }
 572
 573 int
 574 ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
 575                                       struct inode *lower_inode,
 576                                       struct inode *inode,
 577                                       struct dentry *ecryptfs_dentry,
 578                                       int lower_i_mutex_held)
 579 {
 580         struct ecryptfs_crypt_stat *crypt_stat;
 581
 582         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 583         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 584                 return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
 585                                                           ecryptfs_dentry,
 586                                                           lower_i_mutex_held);
 587         else
 588                 return ecryptfs_write_inode_size_to_header(lower_file,
 589                                                            lower_inode,
 590                                                            inode);
 591 }
 592
 593 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 594                             struct file *lower_file,
 595                             unsigned long lower_page_index, int byte_offset,
 596                             int region_bytes)
 597 {
 598         int rc = 0;
 599
 600         rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL, lower_inode,
 601                                               lower_page_index);
 602         if (rc) {
 603                 ecryptfs_printk(KERN_ERR, "Error attempting to grab and map "
 604                                 "lower page with index [0x%.16x]\n",
 605                                 lower_page_index);
 606                 goto out;
 607         }
 608         rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
 609                                                           (*lower_page),
 610                                                           byte_offset,
 611                                                           region_bytes);
 612         if (rc) {
 613                 ecryptfs_printk(KERN_ERR, "prepare_write for "
 614                                 "lower_page_index = [0x%.16x] failed; rc = "
 615                                 "[%d]\n", lower_page_index, rc);
 616         }
 617 out:
 618         if (rc && (*lower_page)) {
 619                 ecryptfs_unmap_and_release_lower_page(*lower_page);
 620                 (*lower_page) = NULL;
 621         }
 622         return rc;
 623 }
 624
 625 /**
 626  * ecryptfs_commit_lower_page
 627  *
 628  * Returns zero on success; non-zero on error
 629  */
 630 int
 631 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
 632                            struct file *lower_file, int byte_offset,
 633                            int region_size)
 634 {
 635         int rc = 0;
 636
 637         rc = lower_inode->i_mapping->a_ops->commit_write(
 638                 lower_file, lower_page, byte_offset, region_size);
 639         if (rc < 0) {
 640                 ecryptfs_printk(KERN_ERR,
 641                                 "Error committing write; rc = [%d]\n", rc);
 642         } else
 643                 rc = 0;
 644         ecryptfs_unmap_and_release_lower_page(lower_page);
 645         return rc;
 646 }
 647
 648 /**
 649  * ecryptfs_copy_page_to_lower
 650  *
 651  * Used for plaintext pass-through; no page index interpolation
 652  * required.
 653  */
 654 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
 655                                 struct file *lower_file)
 656 {
 657         int rc = 0;
 658         struct page *lower_page;
 659
 660         rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
 661                                      page->index, 0, PAGE_CACHE_SIZE);
 662         if (rc) {
 663                 ecryptfs_printk(KERN_ERR, "Error attempting to get page "
 664                                 "at index [0x%.16x]\n", page->index);
 665                 goto out;
 666         }
 667         /* TODO: aops */
 668         memcpy((char *)page_address(lower_page), page_address(page),
 669                PAGE_CACHE_SIZE);
 670         rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
 671                                         0, PAGE_CACHE_SIZE);
 672         if (rc)
 673                 ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
 674                                 "at index [0x%.16x]\n", page->index);
 675 out:
 676         return rc;
 677 }
 678
 679 struct kmem_cache *ecryptfs_xattr_cache;
 680
 681 /**
 682  * ecryptfs_commit_write
 683  * @file: The eCryptfs file object
 684  * @page: The eCryptfs page
 685  * @from: Ignored (we rotate the page IV on each write)
 686  * @to: Ignored
 687  *
 688  * This is where we encrypt the data and pass the encrypted data to
 689  * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 690  * entire underlying packets.
 691  */
 692 static int ecryptfs_commit_write(struct file *file, struct page *page,
 693                                  unsigned from, unsigned to)
 694 {
 695         struct ecryptfs_page_crypt_context ctx;
 696         loff_t pos;
 697         struct inode *inode;
 698         struct inode *lower_inode;
 699         struct file *lower_file;
 700         struct ecryptfs_crypt_stat *crypt_stat;
 701         int rc;
 702
 703         inode = page->mapping->host;
 704         lower_inode = ecryptfs_inode_to_lower(inode);
 705         lower_file = ecryptfs_file_to_lower(file);
 706         mutex_lock(&lower_inode->i_mutex);
 707         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 708                                 ->crypt_stat;
 709         if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE)) {
 710                 ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
 711                         "crypt_stat at memory location [%p]\n", crypt_stat);
 712                 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_NEW_FILE);
 713         } else
 714                 ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
 715         ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
 716                         "(page w/ index = [0x%.16x], to = [%d])\n", page->index,
 717                         to);
 718         rc = fill_zeros_to_end_of_page(page, to);
 719         if (rc) {
 720                 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
 721                                 "zeros in page with index = [0x%.16x]\n",
 722                                 page->index);
 723                 goto out;
 724         }
 725         ctx.page = page;
 726         ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
 727         ctx.param.lower_file = lower_file;
 728         rc = ecryptfs_encrypt_page(&ctx);
 729         if (rc) {
 730                 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
 731                                 "index [0x%.16x])\n", page->index);
 732                 goto out;
 733         }
 734         inode->i_blocks = lower_inode->i_blocks;
 735         pos = (page->index << PAGE_CACHE_SHIFT) + to;
 736         if (pos > i_size_read(inode)) {
 737                 i_size_write(inode, pos);
 738                 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
 739                                 "[0x%.16x]\n", i_size_read(inode));
 740         }
 741         rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
 742                                                    inode, file->f_dentry,
 743                                                    ECRYPTFS_LOWER_I_MUTEX_HELD);
 744         if (rc)
 745                 printk(KERN_ERR "Error writing inode size to metadata; "
 746                        "rc = [%d]\n", rc);
 747         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 748         mark_inode_dirty_sync(inode);
 749 out:
 750         kunmap(page); /* mapped in prior call (prepare_write) */
 751         if (rc < 0)
 752                 ClearPageUptodate(page);
 753         else
 754                 SetPageUptodate(page);
 755         mutex_unlock(&lower_inode->i_mutex);
 756         return rc;
 757 }
 758
 759 /**
 760  * write_zeros
 761  * @file: The ecryptfs file
 762  * @index: The index in which we are writing
 763  * @start: The position after the last block of data
 764  * @num_zeros: The number of zeros to write
 765  *
 766  * Write a specified number of zero's to a page.
 767  *
 768  * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
 769  */
 770 static
 771 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
 772 {
 773         int rc = 0;
 774         struct page *tmp_page;
 775
 776         tmp_page = ecryptfs_get1page(file, index);
 777         if (IS_ERR(tmp_page)) {
 778                 ecryptfs_printk(KERN_ERR, "Error getting page at index "
 779                                 "[0x%.16x]\n", index);
 780                 rc = PTR_ERR(tmp_page);
 781                 goto out;
 782         }
 783         kmap(tmp_page);
 784         rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
 785         if (rc) {
 786                 ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
 787                                 "to remainder of page at index [0x%.16x]\n",
 788                                 index);
 789                 kunmap(tmp_page);
 790                 page_cache_release(tmp_page);
 791                 goto out;
 792         }
 793         memset(((char *)page_address(tmp_page) + start), 0, num_zeros);
 794         rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
 795         if (rc < 0) {
 796                 ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
 797                                 "to remainder of page at index [0x%.16x]\n",
 798                                 index);
 799                 kunmap(tmp_page);
 800                 page_cache_release(tmp_page);
 801                 goto out;
 802         }
 803         rc = 0;
 804         kunmap(tmp_page);
 805         page_cache_release(tmp_page);
 806 out:
 807         return rc;
 808 }
 809
 810 static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
 811 {
 812         int rc = 0;
 813         struct inode *inode;
 814         struct inode *lower_inode;
 815
 816         inode = (struct inode *)mapping->host;
 817         lower_inode = ecryptfs_inode_to_lower(inode);
 818         if (lower_inode->i_mapping->a_ops->bmap)
 819                 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
 820                                                          block);
 821         return rc;
 822 }
 823
 824 static void ecryptfs_sync_page(struct page *page)
 825 {
 826         struct inode *inode;
 827         struct inode *lower_inode;
 828         struct page *lower_page;
 829
 830         inode = page->mapping->host;
 831         lower_inode = ecryptfs_inode_to_lower(inode);
 832         /* NOTE: Recently swapped with grab_cache_page(), since
 833          * sync_page() just makes sure that pending I/O gets done. */
 834         lower_page = find_lock_page(lower_inode->i_mapping, page->index);
 835         if (!lower_page) {
 836                 ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
 837                 return;
 838         }
 839         lower_page->mapping->a_ops->sync_page(lower_page);
 840         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 841                         lower_page->index);
 842         unlock_page(lower_page);
 843         page_cache_release(lower_page);
 844 }
 845
 846 struct address_space_operations ecryptfs_aops = {
 847         .writepage = ecryptfs_writepage,
 848         .readpage = ecryptfs_readpage,
 849         .prepare_write = ecryptfs_prepare_write,
 850         .commit_write = ecryptfs_commit_write,
 851         .bmap = ecryptfs_bmap,
 852         .sync_page = ecryptfs_sync_page,
 853 };