git.oblomov.eu Git - 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 dentry *dentry;
  50         struct inode *inode;
  51         struct address_space *mapping;
  52
  53         dentry = file->f_path.dentry;
  54         inode = dentry->d_inode;
  55         mapping = inode->i_mapping;
  56         return read_mapping_page(mapping, index, (void *)file);
  57 }
  58
  59 static
  60 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros);
  61
  62 /**
  63  * ecryptfs_fill_zeros
  64  * @file: The ecryptfs file
  65  * @new_length: The new length of the data in the underlying file;
  66  *              everything between the prior end of the file and the
  67  *              new end of the file will be filled with zero's.
  68  *              new_length must be greater than  current length
  69  *
  70  * Function for handling lseek-ing past the end of the file.
  71  *
  72  * This function does not support shrinking, only growing a file.
  73  *
  74  * Returns zero on success; non-zero otherwise.
  75  */
  76 int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
  77 {
  78         int rc = 0;
  79         struct dentry *dentry = file->f_path.dentry;
  80         struct inode *inode = dentry->d_inode;
  81         pgoff_t old_end_page_index = 0;
  82         pgoff_t index = old_end_page_index;
  83         int old_end_pos_in_page = -1;
  84         pgoff_t new_end_page_index;
  85         int new_end_pos_in_page;
  86         loff_t cur_length = i_size_read(inode);
  87
  88         if (cur_length != 0) {
  89                 index = old_end_page_index =
  90                     ((cur_length - 1) >> PAGE_CACHE_SHIFT);
  91                 old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
  92         }
  93         new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
  94         new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
  95         ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; "
  96                         "old_end_pos_in_page = [%d]; "
  97                         "new_end_page_index = [0x%.16x]; "
  98                         "new_end_pos_in_page = [%d]\n",
  99                         old_end_page_index, old_end_pos_in_page,
 100                         new_end_page_index, new_end_pos_in_page);
 101         if (old_end_page_index == new_end_page_index) {
 102                 /* Start and end are in the same page; we just need to
 103                  * set a portion of the existing page to zero's */
 104                 rc = write_zeros(file, index, (old_end_pos_in_page + 1),
 105                                  (new_end_pos_in_page - old_end_pos_in_page));
 106                 if (rc)
 107                         ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 108                                         "index=[0x%.16x], "
 109                                         "old_end_pos_in_page=[d], "
 110                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
 111                                         "=[%d]"
 112                                         ")=[d]) returned [%d]\n", file, index,
 113                                         old_end_pos_in_page,
 114                                         new_end_pos_in_page,
 115                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
 116                                         rc);
 117                 goto out;
 118         }
 119         /* Fill the remainder of the previous last page with zeros */
 120         rc = write_zeros(file, index, (old_end_pos_in_page + 1),
 121                          ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
 122         if (rc) {
 123                 ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 124                                 "index=[0x%.16x], old_end_pos_in_page=[d], "
 125                                 "(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
 126                                 "returned [%d]\n", file, index,
 127                                 old_end_pos_in_page,
 128                                 (PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
 129                 goto out;
 130         }
 131         index++;
 132         while (index < new_end_page_index) {
 133                 /* Fill all intermediate pages with zeros */
 134                 rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
 135                 if (rc) {
 136                         ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
 137                                         "index=[0x%.16x], "
 138                                         "old_end_pos_in_page=[d], "
 139                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
 140                                         "=[%d]"
 141                                         ")=[d]) returned [%d]\n", file, index,
 142                                         old_end_pos_in_page,
 143                                         new_end_pos_in_page,
 144                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
 145                                         rc);
 146                         goto out;
 147                 }
 148                 index++;
 149         }
 150         /* Fill the portion at the beginning of the last new page with
 151          * zero's */
 152         rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
 153         if (rc) {
 154                 ecryptfs_printk(KERN_ERR, "write_zeros(file="
 155                                 "[%p], index=[0x%.16x], 0, "
 156                                 "new_end_pos_in_page=[%d]"
 157                                 "returned [%d]\n", file, index,
 158                                 new_end_pos_in_page, rc);
 159                 goto out;
 160         }
 161 out:
 162         return rc;
 163 }
 164
 165 /**
 166  * ecryptfs_writepage
 167  * @page: Page that is locked before this call is made
 168  *
 169  * Returns zero on success; non-zero otherwise
 170  */
 171 static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
 172 {
 173         struct ecryptfs_page_crypt_context ctx;
 174         int rc;
 175
 176         ctx.page = page;
 177         ctx.mode = ECRYPTFS_WRITEPAGE_MODE;
 178         ctx.param.wbc = wbc;
 179         rc = ecryptfs_encrypt_page(&ctx);
 180         if (rc) {
 181                 ecryptfs_printk(KERN_WARNING, "Error encrypting "
 182                                 "page (upper index [0x%.16x])\n", page->index);
 183                 ClearPageUptodate(page);
 184                 goto out;
 185         }
 186         SetPageUptodate(page);
 187         unlock_page(page);
 188 out:
 189         return rc;
 190 }
 191
 192 /**
 193  * Reads the data from the lower file file at index lower_page_index
 194  * and copies that data into page.
 195  *
 196  * @param page  Page to fill
 197  * @param lower_page_index Index of the page in the lower file to get
 198  */
 199 int ecryptfs_do_readpage(struct file *file, struct page *page,
 200                          pgoff_t lower_page_index)
 201 {
 202         int rc;
 203         struct dentry *dentry;
 204         struct file *lower_file;
 205         struct dentry *lower_dentry;
 206         struct inode *inode;
 207         struct inode *lower_inode;
 208         char *page_data;
 209         struct page *lower_page = NULL;
 210         char *lower_page_data;
 211         const struct address_space_operations *lower_a_ops;
 212
 213         dentry = file->f_path.dentry;
 214         lower_file = ecryptfs_file_to_lower(file);
 215         lower_dentry = ecryptfs_dentry_to_lower(dentry);
 216         inode = dentry->d_inode;
 217         lower_inode = ecryptfs_inode_to_lower(inode);
 218         lower_a_ops = lower_inode->i_mapping->a_ops;
 219         lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
 220                                      (filler_t *)lower_a_ops->readpage,
 221                                      (void *)lower_file);
 222         if (IS_ERR(lower_page)) {
 223                 rc = PTR_ERR(lower_page);
 224                 lower_page = NULL;
 225                 ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
 226                 goto out;
 227         }
 228         page_data = kmap_atomic(page, KM_USER0);
 229         lower_page_data = kmap_atomic(lower_page, KM_USER1);
 230         memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
 231         kunmap_atomic(lower_page_data, KM_USER1);
 232         kunmap_atomic(page_data, KM_USER0);
 233         flush_dcache_page(page);
 234         rc = 0;
 235 out:
 236         if (likely(lower_page))
 237                 page_cache_release(lower_page);
 238         if (rc == 0)
 239                 SetPageUptodate(page);
 240         else
 241                 ClearPageUptodate(page);
 242         return rc;
 243 }
 244 /**
 245  *   Header Extent:
 246  *     Octets 0-7:        Unencrypted file size (big-endian)
 247  *     Octets 8-15:       eCryptfs special marker
 248  *     Octets 16-19:      Flags
 249  *      Octet 16:         File format version number (between 0 and 255)
 250  *      Octets 17-18:     Reserved
 251  *      Octet 19:         Bit 1 (lsb): Reserved
 252  *                        Bit 2: Encrypted?
 253  *                        Bits 3-8: Reserved
 254  *     Octets 20-23:      Header extent size (big-endian)
 255  *     Octets 24-25:      Number of header extents at front of file
 256  *                        (big-endian)
 257  *     Octet  26:         Begin RFC 2440 authentication token packet set
 258  */
 259 static void set_header_info(char *page_virt,
 260                             struct ecryptfs_crypt_stat *crypt_stat)
 261 {
 262         size_t written;
 263         int save_num_header_extents_at_front =
 264                 crypt_stat->num_header_extents_at_front;
 265
 266         crypt_stat->num_header_extents_at_front = 1;
 267         ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
 268         crypt_stat->num_header_extents_at_front =
 269                 save_num_header_extents_at_front;
 270 }
 271
 272 /**
 273  * ecryptfs_readpage
 274  * @file: This is an ecryptfs file
 275  * @page: ecryptfs associated page to stick the read data into
 276  *
 277  * Read in a page, decrypting if necessary.
 278  *
 279  * Returns zero on success; non-zero on error.
 280  */
 281 static int ecryptfs_readpage(struct file *file, struct page *page)
 282 {
 283         int rc = 0;
 284         struct ecryptfs_crypt_stat *crypt_stat;
 285
 286         BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
 287         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 288                         ->crypt_stat;
 289         if (!crypt_stat
 290             || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
 291             || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
 292                 ecryptfs_printk(KERN_DEBUG,
 293                                 "Passing through unencrypted page\n");
 294                 rc = ecryptfs_do_readpage(file, page, page->index);
 295                 if (rc) {
 296                         ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
 297                                         "[%d]\n", rc);
 298                         goto out;
 299                 }
 300         } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
 301                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
 302                         int num_pages_in_header_region =
 303                                 (crypt_stat->header_extent_size
 304                                  / PAGE_CACHE_SIZE);
 305
 306                         if (page->index < num_pages_in_header_region) {
 307                                 char *page_virt;
 308
 309                                 page_virt = kmap_atomic(page, KM_USER0);
 310                                 memset(page_virt, 0, PAGE_CACHE_SIZE);
 311                                 if (page->index == 0) {
 312                                         rc = ecryptfs_read_xattr_region(
 313                                                 page_virt, file->f_path.dentry);
 314                                         set_header_info(page_virt, crypt_stat);
 315                                 }
 316                                 kunmap_atomic(page_virt, KM_USER0);
 317                                 flush_dcache_page(page);
 318                                 if (rc) {
 319                                         printk(KERN_ERR "Error reading xattr "
 320                                                "region\n");
 321                                         goto out;
 322                                 }
 323                         } else {
 324                                 rc = ecryptfs_do_readpage(
 325                                         file, page,
 326                                         (page->index
 327                                          - num_pages_in_header_region));
 328                                 if (rc) {
 329                                         printk(KERN_ERR "Error reading page; "
 330                                                "rc = [%d]\n", rc);
 331                                         goto out;
 332                                 }
 333                         }
 334                 } else {
 335                         rc = ecryptfs_do_readpage(file, page, page->index);
 336                         if (rc) {
 337                                 printk(KERN_ERR "Error reading page; rc = "
 338                                        "[%d]\n", rc);
 339                                 goto out;
 340                         }
 341                 }
 342         } else {
 343                 rc = ecryptfs_decrypt_page(file, page);
 344                 if (rc) {
 345                         ecryptfs_printk(KERN_ERR, "Error decrypting page; "
 346                                         "rc = [%d]\n", rc);
 347                         goto out;
 348                 }
 349         }
 350         SetPageUptodate(page);
 351 out:
 352         if (rc)
 353                 ClearPageUptodate(page);
 354         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 355                         page->index);
 356         unlock_page(page);
 357         return rc;
 358 }
 359
 360 /**
 361  * Called with lower inode mutex held.
 362  */
 363 static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
 364 {
 365         struct inode *inode = page->mapping->host;
 366         int end_byte_in_page;
 367
 368         if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
 369                 goto out;
 370         end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
 371         if (to > end_byte_in_page)
 372                 end_byte_in_page = to;
 373         zero_user_page(page, end_byte_in_page,
 374                 PAGE_CACHE_SIZE - end_byte_in_page, KM_USER0);
 375 out:
 376         return 0;
 377 }
 378
 379 /**
 380  * eCryptfs does not currently support holes. When writing after a
 381  * seek past the end of the file, eCryptfs fills in 0's through to the
 382  * current location. The code to fill in the 0's to all the
 383  * intermediate pages calls ecryptfs_prepare_write_no_truncate().
 384  */
 385 static int
 386 ecryptfs_prepare_write_no_truncate(struct file *file, struct page *page,
 387                                    unsigned from, unsigned to)
 388 {
 389         int rc = 0;
 390
 391         if (from == 0 && to == PAGE_CACHE_SIZE)
 392                 goto out;       /* If we are writing a full page, it will be
 393                                    up to date. */
 394         if (!PageUptodate(page))
 395                 rc = ecryptfs_do_readpage(file, page, page->index);
 396 out:
 397         return rc;
 398 }
 399
 400 static int ecryptfs_prepare_write(struct file *file, struct page *page,
 401                                   unsigned from, unsigned to)
 402 {
 403         loff_t pos;
 404         int rc = 0;
 405
 406         if (from == 0 && to == PAGE_CACHE_SIZE)
 407                 goto out;       /* If we are writing a full page, it will be
 408                                    up to date. */
 409         if (!PageUptodate(page))
 410                 rc = ecryptfs_do_readpage(file, page, page->index);
 411         pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
 412         if (pos > i_size_read(page->mapping->host)) {
 413                 rc = ecryptfs_truncate(file->f_path.dentry, pos);
 414                 if (rc) {
 415                         printk(KERN_ERR "Error on attempt to "
 416                                "truncate to (higher) offset [%lld];"
 417                                " rc = [%d]\n", pos, rc);
 418                         goto out;
 419                 }
 420         }
 421 out:
 422         return rc;
 423 }
 424
 425 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
 426                                               struct inode *lower_inode,
 427                                               struct writeback_control *wbc)
 428 {
 429         int rc = 0;
 430
 431         rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
 432         if (rc) {
 433                 ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
 434                                 "rc = [%d]\n", rc);
 435                 goto out;
 436         }
 437         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 438         page_cache_release(lower_page);
 439 out:
 440         return rc;
 441 }
 442
 443 static
 444 void ecryptfs_release_lower_page(struct page *lower_page, int page_locked)
 445 {
 446         if (page_locked)
 447                 unlock_page(lower_page);
 448         page_cache_release(lower_page);
 449 }
 450
 451 /**
 452  * ecryptfs_write_inode_size_to_header
 453  *
 454  * Writes the lower file size to the first 8 bytes of the header.
 455  *
 456  * Returns zero on success; non-zero on error.
 457  */
 458 static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
 459                                                struct inode *lower_inode,
 460                                                struct inode *inode)
 461 {
 462         int rc = 0;
 463         struct page *header_page;
 464         char *header_virt;
 465         const struct address_space_operations *lower_a_ops;
 466         u64 file_size;
 467
 468 retry:
 469         header_page = grab_cache_page(lower_inode->i_mapping, 0);
 470         if (!header_page) {
 471                 ecryptfs_printk(KERN_ERR, "grab_cache_page for "
 472                                 "lower_page_index 0 failed\n");
 473                 rc = -EINVAL;
 474                 goto out;
 475         }
 476         lower_a_ops = lower_inode->i_mapping->a_ops;
 477         rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
 478         if (rc) {
 479                 if (rc == AOP_TRUNCATED_PAGE) {
 480                         ecryptfs_release_lower_page(header_page, 0);
 481                         goto retry;
 482                 } else
 483                         ecryptfs_release_lower_page(header_page, 1);
 484                 goto out;
 485         }
 486         file_size = (u64)i_size_read(inode);
 487         ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
 488         file_size = cpu_to_be64(file_size);
 489         header_virt = kmap_atomic(header_page, KM_USER0);
 490         memcpy(header_virt, &file_size, sizeof(u64));
 491         kunmap_atomic(header_virt, KM_USER0);
 492         flush_dcache_page(header_page);
 493         rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
 494         if (rc < 0)
 495                 ecryptfs_printk(KERN_ERR, "Error commiting header page "
 496                                 "write\n");
 497         if (rc == AOP_TRUNCATED_PAGE) {
 498                 ecryptfs_release_lower_page(header_page, 0);
 499                 goto retry;
 500         } else
 501                 ecryptfs_release_lower_page(header_page, 1);
 502         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 503         mark_inode_dirty_sync(inode);
 504 out:
 505         return rc;
 506 }
 507
 508 static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
 509                                               struct inode *inode,
 510                                               struct dentry *ecryptfs_dentry,
 511                                               int lower_i_mutex_held)
 512 {
 513         ssize_t size;
 514         void *xattr_virt;
 515         struct dentry *lower_dentry;
 516         u64 file_size;
 517         int rc;
 518
 519         xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
 520         if (!xattr_virt) {
 521                 printk(KERN_ERR "Out of memory whilst attempting to write "
 522                        "inode size to xattr\n");
 523                 rc = -ENOMEM;
 524                 goto out;
 525         }
 526         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 527         if (!lower_dentry->d_inode->i_op->getxattr ||
 528                         !lower_dentry->d_inode->i_op->setxattr) {
 529                 printk(KERN_WARNING
 530                        "No support for setting xattr in lower filesystem\n");
 531                 rc = -ENOSYS;
 532                 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 533                 goto out;
 534         }
 535         if (!lower_i_mutex_held)
 536                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 537         size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
 538                                                      ECRYPTFS_XATTR_NAME,
 539                                                      xattr_virt,
 540                                                      PAGE_CACHE_SIZE);
 541         if (!lower_i_mutex_held)
 542                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 543         if (size < 0)
 544                 size = 8;
 545         file_size = (u64)i_size_read(inode);
 546         file_size = cpu_to_be64(file_size);
 547         memcpy(xattr_virt, &file_size, sizeof(u64));
 548         if (!lower_i_mutex_held)
 549                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 550         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
 551                                                    ECRYPTFS_XATTR_NAME,
 552                                                    xattr_virt, size, 0);
 553         if (!lower_i_mutex_held)
 554                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 555         if (rc)
 556                 printk(KERN_ERR "Error whilst attempting to write inode size "
 557                        "to lower file xattr; rc = [%d]\n", rc);
 558         kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 559 out:
 560         return rc;
 561 }
 562
 563 int
 564 ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
 565                                       struct inode *lower_inode,
 566                                       struct inode *inode,
 567                                       struct dentry *ecryptfs_dentry,
 568                                       int lower_i_mutex_held)
 569 {
 570         struct ecryptfs_crypt_stat *crypt_stat;
 571
 572         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 573         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 574                 return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
 575                                                           ecryptfs_dentry,
 576                                                           lower_i_mutex_held);
 577         else
 578                 return ecryptfs_write_inode_size_to_header(lower_file,
 579                                                            lower_inode,
 580                                                            inode);
 581 }
 582
 583 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 584                             struct file *lower_file,
 585                             unsigned long lower_page_index, int byte_offset,
 586                             int region_bytes)
 587 {
 588         int rc = 0;
 589
 590 retry:
 591         *lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
 592         if (!(*lower_page)) {
 593                 rc = -EINVAL;
 594                 ecryptfs_printk(KERN_ERR, "Error attempting to grab "
 595                                 "lower page with index [0x%.16x]\n",
 596                                 lower_page_index);
 597                 goto out;
 598         }
 599         rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
 600                                                           (*lower_page),
 601                                                           byte_offset,
 602                                                           region_bytes);
 603         if (rc) {
 604                 if (rc == AOP_TRUNCATED_PAGE) {
 605                         ecryptfs_release_lower_page(*lower_page, 0);
 606                         goto retry;
 607                 } else {
 608                         ecryptfs_printk(KERN_ERR, "prepare_write for "
 609                                 "lower_page_index = [0x%.16x] failed; rc = "
 610                                 "[%d]\n", lower_page_index, rc);
 611                         ecryptfs_release_lower_page(*lower_page, 1);
 612                         (*lower_page) = NULL;
 613                 }
 614         }
 615 out:
 616         return rc;
 617 }
 618
 619 /**
 620  * ecryptfs_commit_lower_page
 621  *
 622  * Returns zero on success; non-zero on error
 623  */
 624 int
 625 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
 626                            struct file *lower_file, int byte_offset,
 627                            int region_size)
 628 {
 629         int page_locked = 1;
 630         int rc = 0;
 631
 632         rc = lower_inode->i_mapping->a_ops->commit_write(
 633                 lower_file, lower_page, byte_offset, region_size);
 634         if (rc == AOP_TRUNCATED_PAGE)
 635                 page_locked = 0;
 636         if (rc < 0) {
 637                 ecryptfs_printk(KERN_ERR,
 638                                 "Error committing write; rc = [%d]\n", rc);
 639         } else
 640                 rc = 0;
 641         ecryptfs_release_lower_page(lower_page, page_locked);
 642         return rc;
 643 }
 644
 645 /**
 646  * ecryptfs_copy_page_to_lower
 647  *
 648  * Used for plaintext pass-through; no page index interpolation
 649  * required.
 650  */
 651 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
 652                                 struct file *lower_file)
 653 {
 654         int rc = 0;
 655         struct page *lower_page;
 656
 657         rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
 658                                      page->index, 0, PAGE_CACHE_SIZE);
 659         if (rc) {
 660                 ecryptfs_printk(KERN_ERR, "Error attempting to get page "
 661                                 "at index [0x%.16x]\n", page->index);
 662                 goto out;
 663         }
 664         /* TODO: aops */
 665         memcpy((char *)page_address(lower_page), page_address(page),
 666                PAGE_CACHE_SIZE);
 667         rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
 668                                         0, PAGE_CACHE_SIZE);
 669         if (rc)
 670                 ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
 671                                 "at index [0x%.16x]\n", page->index);
 672 out:
 673         return rc;
 674 }
 675
 676 struct kmem_cache *ecryptfs_xattr_cache;
 677
 678 /**
 679  * ecryptfs_commit_write
 680  * @file: The eCryptfs file object
 681  * @page: The eCryptfs page
 682  * @from: Ignored (we rotate the page IV on each write)
 683  * @to: Ignored
 684  *
 685  * This is where we encrypt the data and pass the encrypted data to
 686  * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 687  * entire underlying packets.
 688  */
 689 static int ecryptfs_commit_write(struct file *file, struct page *page,
 690                                  unsigned from, unsigned to)
 691 {
 692         struct ecryptfs_page_crypt_context ctx;
 693         loff_t pos;
 694         struct inode *inode;
 695         struct inode *lower_inode;
 696         struct file *lower_file;
 697         struct ecryptfs_crypt_stat *crypt_stat;
 698         int rc;
 699
 700         inode = page->mapping->host;
 701         lower_inode = ecryptfs_inode_to_lower(inode);
 702         lower_file = ecryptfs_file_to_lower(file);
 703         mutex_lock(&lower_inode->i_mutex);
 704         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 705                                 ->crypt_stat;
 706         if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
 707                 ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
 708                         "crypt_stat at memory location [%p]\n", crypt_stat);
 709                 crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
 710         } else
 711                 ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
 712         ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
 713                         "(page w/ index = [0x%.16x], to = [%d])\n", page->index,
 714                         to);
 715         rc = fill_zeros_to_end_of_page(page, to);
 716         if (rc) {
 717                 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
 718                                 "zeros in page with index = [0x%.16x]\n",
 719                                 page->index);
 720                 goto out;
 721         }
 722         ctx.page = page;
 723         ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
 724         ctx.param.lower_file = lower_file;
 725         rc = ecryptfs_encrypt_page(&ctx);
 726         if (rc) {
 727                 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
 728                                 "index [0x%.16x])\n", page->index);
 729                 goto out;
 730         }
 731         inode->i_blocks = lower_inode->i_blocks;
 732         pos = (page->index << PAGE_CACHE_SHIFT) + to;
 733         if (pos > i_size_read(inode)) {
 734                 i_size_write(inode, pos);
 735                 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
 736                                 "[0x%.16x]\n", i_size_read(inode));
 737         }
 738         rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
 739                                                    inode, file->f_dentry,
 740                                                    ECRYPTFS_LOWER_I_MUTEX_HELD);
 741         if (rc)
 742                 printk(KERN_ERR "Error writing inode size to metadata; "
 743                        "rc = [%d]\n", rc);
 744         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 745         mark_inode_dirty_sync(inode);
 746 out:
 747         if (rc < 0)
 748                 ClearPageUptodate(page);
 749         else
 750                 SetPageUptodate(page);
 751         mutex_unlock(&lower_inode->i_mutex);
 752         return rc;
 753 }
 754
 755 /**
 756  * write_zeros
 757  * @file: The ecryptfs file
 758  * @index: The index in which we are writing
 759  * @start: The position after the last block of data
 760  * @num_zeros: The number of zeros to write
 761  *
 762  * Write a specified number of zero's to a page.
 763  *
 764  * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
 765  */
 766 static
 767 int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
 768 {
 769         int rc = 0;
 770         struct page *tmp_page;
 771
 772         tmp_page = ecryptfs_get1page(file, index);
 773         if (IS_ERR(tmp_page)) {
 774                 ecryptfs_printk(KERN_ERR, "Error getting page at index "
 775                                 "[0x%.16x]\n", index);
 776                 rc = PTR_ERR(tmp_page);
 777                 goto out;
 778         }
 779         if ((rc = ecryptfs_prepare_write_no_truncate(file, tmp_page, start,
 780                                                      (start + num_zeros)))) {
 781                 ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
 782                                 "to page at index [0x%.16x]\n",
 783                                 index);
 784                 page_cache_release(tmp_page);
 785                 goto out;
 786         }
 787         zero_user_page(tmp_page, start, num_zeros, KM_USER0);
 788         rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
 789         if (rc < 0) {
 790                 ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
 791                                 "to remainder of page at index [0x%.16x]\n",
 792                                 index);
 793                 page_cache_release(tmp_page);
 794                 goto out;
 795         }
 796         rc = 0;
 797         page_cache_release(tmp_page);
 798 out:
 799         return rc;
 800 }
 801
 802 static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
 803 {
 804         int rc = 0;
 805         struct inode *inode;
 806         struct inode *lower_inode;
 807
 808         inode = (struct inode *)mapping->host;
 809         lower_inode = ecryptfs_inode_to_lower(inode);
 810         if (lower_inode->i_mapping->a_ops->bmap)
 811                 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
 812                                                          block);
 813         return rc;
 814 }
 815
 816 static void ecryptfs_sync_page(struct page *page)
 817 {
 818         struct inode *inode;
 819         struct inode *lower_inode;
 820         struct page *lower_page;
 821
 822         inode = page->mapping->host;
 823         lower_inode = ecryptfs_inode_to_lower(inode);
 824         /* NOTE: Recently swapped with grab_cache_page(), since
 825          * sync_page() just makes sure that pending I/O gets done. */
 826         lower_page = find_lock_page(lower_inode->i_mapping, page->index);
 827         if (!lower_page) {
 828                 ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
 829                 return;
 830         }
 831         lower_page->mapping->a_ops->sync_page(lower_page);
 832         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 833                         lower_page->index);
 834         unlock_page(lower_page);
 835         page_cache_release(lower_page);
 836 }
 837
 838 struct address_space_operations ecryptfs_aops = {
 839         .writepage = ecryptfs_writepage,
 840         .readpage = ecryptfs_readpage,
 841         .prepare_write = ecryptfs_prepare_write,
 842         .commit_write = ecryptfs_commit_write,
 843         .bmap = ecryptfs_bmap,
 844         .sync_page = ecryptfs_sync_page,
 845 };