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->header_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 =
 413                         (((loff_t)page->index << PAGE_CACHE_SHIFT) - 1);
 414
 415                 if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) {
 416                         rc = ecryptfs_truncate(file->f_path.dentry,
 417                                                end_of_prev_pg_pos);
 418                         if (rc) {
 419                                 printk(KERN_ERR "Error on attempt to "
 420                                        "truncate to (higher) offset [%lld];"
 421                                        " rc = [%d]\n", end_of_prev_pg_pos, rc);
 422                                 goto out;
 423                         }
 424                 }
 425                 if (end_of_prev_pg_pos + 1 > i_size_read(page->mapping->host))
 426                         zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
 427         }
 428 out:
 429         return rc;
 430 }
 431
 432 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
 433                                               struct inode *lower_inode,
 434                                               struct writeback_control *wbc)
 435 {
 436         int rc = 0;
 437
 438         rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
 439         if (rc) {
 440                 ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
 441                                 "rc = [%d]\n", rc);
 442                 goto out;
 443         }
 444         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 445         page_cache_release(lower_page);
 446 out:
 447         return rc;
 448 }
 449
 450 static
 451 void ecryptfs_release_lower_page(struct page *lower_page, int page_locked)
 452 {
 453         if (page_locked)
 454                 unlock_page(lower_page);
 455         page_cache_release(lower_page);
 456 }
 457
 458 /**
 459  * ecryptfs_write_inode_size_to_header
 460  *
 461  * Writes the lower file size to the first 8 bytes of the header.
 462  *
 463  * Returns zero on success; non-zero on error.
 464  */
 465 static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
 466                                                struct inode *lower_inode,
 467                                                struct inode *inode)
 468 {
 469         int rc = 0;
 470         struct page *header_page;
 471         char *header_virt;
 472         const struct address_space_operations *lower_a_ops;
 473         u64 file_size;
 474
 475 retry:
 476         header_page = grab_cache_page(lower_inode->i_mapping, 0);
 477         if (!header_page) {
 478                 ecryptfs_printk(KERN_ERR, "grab_cache_page for "
 479                                 "lower_page_index 0 failed\n");
 480                 rc = -EINVAL;
 481                 goto out;
 482         }
 483         lower_a_ops = lower_inode->i_mapping->a_ops;
 484         rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
 485         if (rc) {
 486                 if (rc == AOP_TRUNCATED_PAGE) {
 487                         ecryptfs_release_lower_page(header_page, 0);
 488                         goto retry;
 489                 } else
 490                         ecryptfs_release_lower_page(header_page, 1);
 491                 goto out;
 492         }
 493         file_size = (u64)i_size_read(inode);
 494         ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
 495         file_size = cpu_to_be64(file_size);
 496         header_virt = kmap_atomic(header_page, KM_USER0);
 497         memcpy(header_virt, &file_size, sizeof(u64));
 498         kunmap_atomic(header_virt, KM_USER0);
 499         flush_dcache_page(header_page);
 500         rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
 501         if (rc < 0)
 502                 ecryptfs_printk(KERN_ERR, "Error commiting header page "
 503                                 "write\n");
 504         if (rc == AOP_TRUNCATED_PAGE) {
 505                 ecryptfs_release_lower_page(header_page, 0);
 506                 goto retry;
 507         } else
 508                 ecryptfs_release_lower_page(header_page, 1);
 509         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 510         mark_inode_dirty_sync(inode);
 511 out:
 512         return rc;
 513 }
 514
 515 static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
 516                                               struct inode *inode,
 517                                               struct dentry *ecryptfs_dentry,
 518                                               int lower_i_mutex_held)
 519 {
 520         ssize_t size;
 521         void *xattr_virt;
 522         struct dentry *lower_dentry;
 523         u64 file_size;
 524         int rc;
 525
 526         xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
 527         if (!xattr_virt) {
 528                 printk(KERN_ERR "Out of memory whilst attempting to write "
 529                        "inode size to xattr\n");
 530                 rc = -ENOMEM;
 531                 goto out;
 532         }
 533         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
 534         if (!lower_dentry->d_inode->i_op->getxattr ||
 535                         !lower_dentry->d_inode->i_op->setxattr) {
 536                 printk(KERN_WARNING
 537                        "No support for setting xattr in lower filesystem\n");
 538                 rc = -ENOSYS;
 539                 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 540                 goto out;
 541         }
 542         if (!lower_i_mutex_held)
 543                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 544         size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
 545                                                      ECRYPTFS_XATTR_NAME,
 546                                                      xattr_virt,
 547                                                      PAGE_CACHE_SIZE);
 548         if (!lower_i_mutex_held)
 549                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 550         if (size < 0)
 551                 size = 8;
 552         file_size = (u64)i_size_read(inode);
 553         file_size = cpu_to_be64(file_size);
 554         memcpy(xattr_virt, &file_size, sizeof(u64));
 555         if (!lower_i_mutex_held)
 556                 mutex_lock(&lower_dentry->d_inode->i_mutex);
 557         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
 558                                                    ECRYPTFS_XATTR_NAME,
 559                                                    xattr_virt, size, 0);
 560         if (!lower_i_mutex_held)
 561                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
 562         if (rc)
 563                 printk(KERN_ERR "Error whilst attempting to write inode size "
 564                        "to lower file xattr; rc = [%d]\n", rc);
 565         kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
 566 out:
 567         return rc;
 568 }
 569
 570 int
 571 ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
 572                                       struct inode *lower_inode,
 573                                       struct inode *inode,
 574                                       struct dentry *ecryptfs_dentry,
 575                                       int lower_i_mutex_held)
 576 {
 577         struct ecryptfs_crypt_stat *crypt_stat;
 578
 579         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
 580         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
 581                 return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
 582                                                           ecryptfs_dentry,
 583                                                           lower_i_mutex_held);
 584         else
 585                 return ecryptfs_write_inode_size_to_header(lower_file,
 586                                                            lower_inode,
 587                                                            inode);
 588 }
 589
 590 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
 591                             struct file *lower_file,
 592                             unsigned long lower_page_index, int byte_offset,
 593                             int region_bytes)
 594 {
 595         int rc = 0;
 596
 597 retry:
 598         *lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
 599         if (!(*lower_page)) {
 600                 rc = -EINVAL;
 601                 ecryptfs_printk(KERN_ERR, "Error attempting to grab "
 602                                 "lower page with index [0x%.16x]\n",
 603                                 lower_page_index);
 604                 goto out;
 605         }
 606         rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
 607                                                           (*lower_page),
 608                                                           byte_offset,
 609                                                           region_bytes);
 610         if (rc) {
 611                 if (rc == AOP_TRUNCATED_PAGE) {
 612                         ecryptfs_release_lower_page(*lower_page, 0);
 613                         goto retry;
 614                 } else {
 615                         ecryptfs_printk(KERN_ERR, "prepare_write for "
 616                                 "lower_page_index = [0x%.16x] failed; rc = "
 617                                 "[%d]\n", lower_page_index, rc);
 618                         ecryptfs_release_lower_page(*lower_page, 1);
 619                         (*lower_page) = NULL;
 620                 }
 621         }
 622 out:
 623         return rc;
 624 }
 625
 626 /**
 627  * ecryptfs_commit_lower_page
 628  *
 629  * Returns zero on success; non-zero on error
 630  */
 631 int
 632 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
 633                            struct file *lower_file, int byte_offset,
 634                            int region_size)
 635 {
 636         int page_locked = 1;
 637         int rc = 0;
 638
 639         rc = lower_inode->i_mapping->a_ops->commit_write(
 640                 lower_file, lower_page, byte_offset, region_size);
 641         if (rc == AOP_TRUNCATED_PAGE)
 642                 page_locked = 0;
 643         if (rc < 0) {
 644                 ecryptfs_printk(KERN_ERR,
 645                                 "Error committing write; rc = [%d]\n", rc);
 646         } else
 647                 rc = 0;
 648         ecryptfs_release_lower_page(lower_page, page_locked);
 649         return rc;
 650 }
 651
 652 /**
 653  * ecryptfs_copy_page_to_lower
 654  *
 655  * Used for plaintext pass-through; no page index interpolation
 656  * required.
 657  */
 658 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
 659                                 struct file *lower_file)
 660 {
 661         int rc = 0;
 662         struct page *lower_page;
 663
 664         rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
 665                                      page->index, 0, PAGE_CACHE_SIZE);
 666         if (rc) {
 667                 ecryptfs_printk(KERN_ERR, "Error attempting to get page "
 668                                 "at index [0x%.16x]\n", page->index);
 669                 goto out;
 670         }
 671         /* TODO: aops */
 672         memcpy((char *)page_address(lower_page), page_address(page),
 673                PAGE_CACHE_SIZE);
 674         rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
 675                                         0, PAGE_CACHE_SIZE);
 676         if (rc)
 677                 ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
 678                                 "at index [0x%.16x]\n", page->index);
 679 out:
 680         return rc;
 681 }
 682
 683 struct kmem_cache *ecryptfs_xattr_cache;
 684
 685 /**
 686  * ecryptfs_commit_write
 687  * @file: The eCryptfs file object
 688  * @page: The eCryptfs page
 689  * @from: Ignored (we rotate the page IV on each write)
 690  * @to: Ignored
 691  *
 692  * This is where we encrypt the data and pass the encrypted data to
 693  * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 694  * entire underlying packets.
 695  */
 696 static int ecryptfs_commit_write(struct file *file, struct page *page,
 697                                  unsigned from, unsigned to)
 698 {
 699         struct ecryptfs_page_crypt_context ctx;
 700         loff_t pos;
 701         struct inode *inode;
 702         struct inode *lower_inode;
 703         struct file *lower_file;
 704         struct ecryptfs_crypt_stat *crypt_stat;
 705         int rc;
 706
 707         inode = page->mapping->host;
 708         lower_inode = ecryptfs_inode_to_lower(inode);
 709         lower_file = ecryptfs_file_to_lower(file);
 710         mutex_lock(&lower_inode->i_mutex);
 711         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
 712                                 ->crypt_stat;
 713         if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
 714                 ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
 715                         "crypt_stat at memory location [%p]\n", crypt_stat);
 716                 crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
 717         } else
 718                 ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
 719         ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
 720                         "(page w/ index = [0x%.16x], to = [%d])\n", page->index,
 721                         to);
 722         rc = fill_zeros_to_end_of_page(page, to);
 723         if (rc) {
 724                 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
 725                                 "zeros in page with index = [0x%.16x]\n",
 726                                 page->index);
 727                 goto out;
 728         }
 729         ctx.page = page;
 730         ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
 731         ctx.param.lower_file = lower_file;
 732         rc = ecryptfs_encrypt_page(&ctx);
 733         if (rc) {
 734                 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
 735                                 "index [0x%.16x])\n", page->index);
 736                 goto out;
 737         }
 738         inode->i_blocks = lower_inode->i_blocks;
 739         pos = (page->index << PAGE_CACHE_SHIFT) + to;
 740         if (pos > i_size_read(inode)) {
 741                 i_size_write(inode, pos);
 742                 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
 743                                 "[0x%.16x]\n", i_size_read(inode));
 744         }
 745         rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
 746                                                    inode, file->f_dentry,
 747                                                    ECRYPTFS_LOWER_I_MUTEX_HELD);
 748         if (rc)
 749                 printk(KERN_ERR "Error writing inode size to metadata; "
 750                        "rc = [%d]\n", rc);
 751         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
 752         mark_inode_dirty_sync(inode);
 753 out:
 754         if (rc < 0)
 755                 ClearPageUptodate(page);
 756         else
 757                 SetPageUptodate(page);
 758         mutex_unlock(&lower_inode->i_mutex);
 759         return rc;
 760 }
 761
 762 /**
 763  * ecryptfs_write_zeros
 764  * @file: The ecryptfs file
 765  * @index: The index in which we are writing
 766  * @start: The position after the last block of data
 767  * @num_zeros: The number of zeros to write
 768  *
 769  * Write a specified number of zero's to a page.
 770  *
 771  * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
 772  */
 773 int
 774 ecryptfs_write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
 775 {
 776         int rc = 0;
 777         struct page *tmp_page;
 778
 779         tmp_page = ecryptfs_get1page(file, index);
 780         if (IS_ERR(tmp_page)) {
 781                 ecryptfs_printk(KERN_ERR, "Error getting page at index "
 782                                 "[0x%.16x]\n", index);
 783                 rc = PTR_ERR(tmp_page);
 784                 goto out;
 785         }
 786         if ((rc = ecryptfs_prepare_write_no_truncate(file, tmp_page, start,
 787                                                      (start + num_zeros)))) {
 788                 ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
 789                                 "to page at index [0x%.16x]\n",
 790                                 index);
 791                 page_cache_release(tmp_page);
 792                 goto out;
 793         }
 794         zero_user_page(tmp_page, start, num_zeros, KM_USER0);
 795         rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
 796         if (rc < 0) {
 797                 ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
 798                                 "to remainder of page at index [0x%.16x]\n",
 799                                 index);
 800                 page_cache_release(tmp_page);
 801                 goto out;
 802         }
 803         rc = 0;
 804         page_cache_release(tmp_page);
 805 out:
 806         return rc;
 807 }
 808
 809 static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
 810 {
 811         int rc = 0;
 812         struct inode *inode;
 813         struct inode *lower_inode;
 814
 815         inode = (struct inode *)mapping->host;
 816         lower_inode = ecryptfs_inode_to_lower(inode);
 817         if (lower_inode->i_mapping->a_ops->bmap)
 818                 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
 819                                                          block);
 820         return rc;
 821 }
 822
 823 static void ecryptfs_sync_page(struct page *page)
 824 {
 825         struct inode *inode;
 826         struct inode *lower_inode;
 827         struct page *lower_page;
 828
 829         inode = page->mapping->host;
 830         lower_inode = ecryptfs_inode_to_lower(inode);
 831         /* NOTE: Recently swapped with grab_cache_page(), since
 832          * sync_page() just makes sure that pending I/O gets done. */
 833         lower_page = find_lock_page(lower_inode->i_mapping, page->index);
 834         if (!lower_page) {
 835                 ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
 836                 return;
 837         }
 838         lower_page->mapping->a_ops->sync_page(lower_page);
 839         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
 840                         lower_page->index);
 841         unlock_page(lower_page);
 842         page_cache_release(lower_page);
 843 }
 844
 845 struct address_space_operations ecryptfs_aops = {
 846         .writepage = ecryptfs_writepage,
 847         .readpage = ecryptfs_readpage,
 848         .prepare_write = ecryptfs_prepare_write,
 849         .commit_write = ecryptfs_commit_write,
 850         .bmap = ecryptfs_bmap,
 851         .sync_page = ecryptfs_sync_page,
 852 };