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