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