1 /** 2 * eCryptfs: Linux filesystem encryption layer 3 * 4 * Copyright (C) 2007 International Business Machines Corp. 5 * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com> 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as 9 * published by the Free Software Foundation; either version 2 of the 10 * License, or (at your option) any later version. 11 * 12 * This program is distributed in the hope that it will be useful, but 13 * WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 * General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program; if not, write to the Free Software 19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 20 * 02111-1307, USA. 21 */ 22 23 #include <linux/fs.h> 24 #include <linux/pagemap.h> 25 #include "ecryptfs_kernel.h" 26 27 /** 28 * ecryptfs_write_lower 29 * @ecryptfs_inode: The eCryptfs inode 30 * @data: Data to write 31 * @offset: Byte offset in the lower file to which to write the data 32 * @size: Number of bytes from @data to write at @offset in the lower 33 * file 34 * 35 * Write data to the lower file. 36 * 37 * Returns zero on success; non-zero on error 38 */ 39 int ecryptfs_write_lower(struct inode *ecryptfs_inode, char *data, 40 loff_t offset, size_t size) 41 { 42 struct ecryptfs_inode_info *inode_info; 43 ssize_t octets_written; 44 mm_segment_t fs_save; 45 int rc = 0; 46 47 inode_info = ecryptfs_inode_to_private(ecryptfs_inode); 48 mutex_lock(&inode_info->lower_file_mutex); 49 BUG_ON(!inode_info->lower_file); 50 inode_info->lower_file->f_pos = offset; 51 fs_save = get_fs(); 52 set_fs(get_ds()); 53 octets_written = vfs_write(inode_info->lower_file, data, size, 54 &inode_info->lower_file->f_pos); 55 set_fs(fs_save); 56 if (octets_written < 0) { 57 printk(KERN_ERR "%s: octets_written = [%td]; " 58 "expected [%td]\n", __FUNCTION__, octets_written, size); 59 rc = -EINVAL; 60 } 61 mutex_unlock(&inode_info->lower_file_mutex); 62 mark_inode_dirty_sync(ecryptfs_inode); 63 return rc; 64 } 65 66 /** 67 * ecryptfs_write_lower_page_segment 68 * @ecryptfs_inode: The eCryptfs inode 69 * @page_for_lower: The page containing the data to be written to the 70 * lower file 71 * @offset_in_page: The offset in the @page_for_lower from which to 72 * start writing the data 73 * @size: The amount of data from @page_for_lower to write to the 74 * lower file 75 * 76 * Determines the byte offset in the file for the given page and 77 * offset within the page, maps the page, and makes the call to write 78 * the contents of @page_for_lower to the lower inode. 79 * 80 * Returns zero on success; non-zero otherwise 81 */ 82 int ecryptfs_write_lower_page_segment(struct inode *ecryptfs_inode, 83 struct page *page_for_lower, 84 size_t offset_in_page, size_t size) 85 { 86 char *virt; 87 loff_t offset; 88 int rc; 89 90 offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT) 91 + offset_in_page); 92 virt = kmap(page_for_lower); 93 rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size); 94 kunmap(page_for_lower); 95 return rc; 96 } 97 98 /** 99 * ecryptfs_write 100 * @ecryptfs_file: The eCryptfs file into which to write 101 * @data: Virtual address where data to write is located 102 * @offset: Offset in the eCryptfs file at which to begin writing the 103 * data from @data 104 * @size: The number of bytes to write from @data 105 * 106 * Write an arbitrary amount of data to an arbitrary location in the 107 * eCryptfs inode page cache. This is done on a page-by-page, and then 108 * by an extent-by-extent, basis; individual extents are encrypted and 109 * written to the lower page cache (via VFS writes). This function 110 * takes care of all the address translation to locations in the lower 111 * filesystem; it also handles truncate events, writing out zeros 112 * where necessary. 113 * 114 * Returns zero on success; non-zero otherwise 115 */ 116 int ecryptfs_write(struct file *ecryptfs_file, char *data, loff_t offset, 117 size_t size) 118 { 119 struct page *ecryptfs_page; 120 char *ecryptfs_page_virt; 121 loff_t ecryptfs_file_size = 122 i_size_read(ecryptfs_file->f_dentry->d_inode); 123 loff_t data_offset = 0; 124 loff_t pos; 125 int rc = 0; 126 127 /* 128 * if we are writing beyond current size, then start pos 129 * at the current size - we'll fill in zeros from there. 130 */ 131 if (offset > ecryptfs_file_size) 132 pos = ecryptfs_file_size; 133 else 134 pos = offset; 135 while (pos < (offset + size)) { 136 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); 137 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); 138 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); 139 size_t total_remaining_bytes = ((offset + size) - pos); 140 141 if (num_bytes > total_remaining_bytes) 142 num_bytes = total_remaining_bytes; 143 if (pos < offset) { 144 /* remaining zeros to write, up to destination offset */ 145 size_t total_remaining_zeros = (offset - pos); 146 147 if (num_bytes > total_remaining_zeros) 148 num_bytes = total_remaining_zeros; 149 } 150 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file, 151 ecryptfs_page_idx); 152 if (IS_ERR(ecryptfs_page)) { 153 rc = PTR_ERR(ecryptfs_page); 154 printk(KERN_ERR "%s: Error getting page at " 155 "index [%ld] from eCryptfs inode " 156 "mapping; rc = [%d]\n", __FUNCTION__, 157 ecryptfs_page_idx, rc); 158 goto out; 159 } 160 if (start_offset_in_page) { 161 /* Read in the page from the lower 162 * into the eCryptfs inode page cache, 163 * decrypting */ 164 rc = ecryptfs_decrypt_page(ecryptfs_page); 165 if (rc) { 166 printk(KERN_ERR "%s: Error decrypting " 167 "page; rc = [%d]\n", 168 __FUNCTION__, rc); 169 ClearPageUptodate(ecryptfs_page); 170 page_cache_release(ecryptfs_page); 171 goto out; 172 } 173 } 174 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); 175 176 /* 177 * pos: where we're now writing, offset: where the request was 178 * If current pos is before request, we are filling zeros 179 * If we are at or beyond request, we are writing the *data* 180 * If we're in a fresh page beyond eof, zero it in either case 181 */ 182 if (pos < offset || !start_offset_in_page) { 183 /* We are extending past the previous end of the file. 184 * Fill in zero values to the end of the page */ 185 memset(((char *)ecryptfs_page_virt 186 + start_offset_in_page), 0, 187 PAGE_CACHE_SIZE - start_offset_in_page); 188 } 189 190 /* pos >= offset, we are now writing the data request */ 191 if (pos >= offset) { 192 memcpy(((char *)ecryptfs_page_virt 193 + start_offset_in_page), 194 (data + data_offset), num_bytes); 195 data_offset += num_bytes; 196 } 197 kunmap_atomic(ecryptfs_page_virt, KM_USER0); 198 flush_dcache_page(ecryptfs_page); 199 SetPageUptodate(ecryptfs_page); 200 unlock_page(ecryptfs_page); 201 rc = ecryptfs_encrypt_page(ecryptfs_page); 202 page_cache_release(ecryptfs_page); 203 if (rc) { 204 printk(KERN_ERR "%s: Error encrypting " 205 "page; rc = [%d]\n", __FUNCTION__, rc); 206 goto out; 207 } 208 pos += num_bytes; 209 } 210 if ((offset + size) > ecryptfs_file_size) { 211 i_size_write(ecryptfs_file->f_dentry->d_inode, (offset + size)); 212 rc = ecryptfs_write_inode_size_to_metadata( 213 ecryptfs_file->f_dentry->d_inode); 214 if (rc) { 215 printk(KERN_ERR "Problem with " 216 "ecryptfs_write_inode_size_to_metadata; " 217 "rc = [%d]\n", rc); 218 goto out; 219 } 220 } 221 out: 222 return rc; 223 } 224 225 /** 226 * ecryptfs_read_lower 227 * @data: The read data is stored here by this function 228 * @offset: Byte offset in the lower file from which to read the data 229 * @size: Number of bytes to read from @offset of the lower file and 230 * store into @data 231 * @ecryptfs_inode: The eCryptfs inode 232 * 233 * Read @size bytes of data at byte offset @offset from the lower 234 * inode into memory location @data. 235 * 236 * Returns zero on success; non-zero on error 237 */ 238 int ecryptfs_read_lower(char *data, loff_t offset, size_t size, 239 struct inode *ecryptfs_inode) 240 { 241 struct ecryptfs_inode_info *inode_info = 242 ecryptfs_inode_to_private(ecryptfs_inode); 243 ssize_t octets_read; 244 mm_segment_t fs_save; 245 int rc = 0; 246 247 mutex_lock(&inode_info->lower_file_mutex); 248 BUG_ON(!inode_info->lower_file); 249 inode_info->lower_file->f_pos = offset; 250 fs_save = get_fs(); 251 set_fs(get_ds()); 252 octets_read = vfs_read(inode_info->lower_file, data, size, 253 &inode_info->lower_file->f_pos); 254 set_fs(fs_save); 255 if (octets_read < 0) { 256 printk(KERN_ERR "%s: octets_read = [%td]; " 257 "expected [%td]\n", __FUNCTION__, octets_read, size); 258 rc = -EINVAL; 259 } 260 mutex_unlock(&inode_info->lower_file_mutex); 261 return rc; 262 } 263 264 /** 265 * ecryptfs_read_lower_page_segment 266 * @page_for_ecryptfs: The page into which data for eCryptfs will be 267 * written 268 * @offset_in_page: Offset in @page_for_ecryptfs from which to start 269 * writing 270 * @size: The number of bytes to write into @page_for_ecryptfs 271 * @ecryptfs_inode: The eCryptfs inode 272 * 273 * Determines the byte offset in the file for the given page and 274 * offset within the page, maps the page, and makes the call to read 275 * the contents of @page_for_ecryptfs from the lower inode. 276 * 277 * Returns zero on success; non-zero otherwise 278 */ 279 int ecryptfs_read_lower_page_segment(struct page *page_for_ecryptfs, 280 pgoff_t page_index, 281 size_t offset_in_page, size_t size, 282 struct inode *ecryptfs_inode) 283 { 284 char *virt; 285 loff_t offset; 286 int rc; 287 288 offset = ((((loff_t)page_index) << PAGE_CACHE_SHIFT) + offset_in_page); 289 virt = kmap(page_for_ecryptfs); 290 rc = ecryptfs_read_lower(virt, offset, size, ecryptfs_inode); 291 kunmap(page_for_ecryptfs); 292 flush_dcache_page(page_for_ecryptfs); 293 return rc; 294 } 295 296 #if 0 297 /** 298 * ecryptfs_read 299 * @data: The virtual address into which to write the data read (and 300 * possibly decrypted) from the lower file 301 * @offset: The offset in the decrypted view of the file from which to 302 * read into @data 303 * @size: The number of bytes to read into @data 304 * @ecryptfs_file: The eCryptfs file from which to read 305 * 306 * Read an arbitrary amount of data from an arbitrary location in the 307 * eCryptfs page cache. This is done on an extent-by-extent basis; 308 * individual extents are decrypted and read from the lower page 309 * cache (via VFS reads). This function takes care of all the 310 * address translation to locations in the lower filesystem. 311 * 312 * Returns zero on success; non-zero otherwise 313 */ 314 int ecryptfs_read(char *data, loff_t offset, size_t size, 315 struct file *ecryptfs_file) 316 { 317 struct page *ecryptfs_page; 318 char *ecryptfs_page_virt; 319 loff_t ecryptfs_file_size = 320 i_size_read(ecryptfs_file->f_dentry->d_inode); 321 loff_t data_offset = 0; 322 loff_t pos; 323 int rc = 0; 324 325 if ((offset + size) > ecryptfs_file_size) { 326 rc = -EINVAL; 327 printk(KERN_ERR "%s: Attempt to read data past the end of the " 328 "file; offset = [%lld]; size = [%td]; " 329 "ecryptfs_file_size = [%lld]\n", 330 __FUNCTION__, offset, size, ecryptfs_file_size); 331 goto out; 332 } 333 pos = offset; 334 while (pos < (offset + size)) { 335 pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); 336 size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); 337 size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); 338 size_t total_remaining_bytes = ((offset + size) - pos); 339 340 if (num_bytes > total_remaining_bytes) 341 num_bytes = total_remaining_bytes; 342 ecryptfs_page = ecryptfs_get_locked_page(ecryptfs_file, 343 ecryptfs_page_idx); 344 if (IS_ERR(ecryptfs_page)) { 345 rc = PTR_ERR(ecryptfs_page); 346 printk(KERN_ERR "%s: Error getting page at " 347 "index [%ld] from eCryptfs inode " 348 "mapping; rc = [%d]\n", __FUNCTION__, 349 ecryptfs_page_idx, rc); 350 goto out; 351 } 352 rc = ecryptfs_decrypt_page(ecryptfs_page); 353 if (rc) { 354 printk(KERN_ERR "%s: Error decrypting " 355 "page; rc = [%d]\n", __FUNCTION__, rc); 356 ClearPageUptodate(ecryptfs_page); 357 page_cache_release(ecryptfs_page); 358 goto out; 359 } 360 ecryptfs_page_virt = kmap_atomic(ecryptfs_page, KM_USER0); 361 memcpy((data + data_offset), 362 ((char *)ecryptfs_page_virt + start_offset_in_page), 363 num_bytes); 364 kunmap_atomic(ecryptfs_page_virt, KM_USER0); 365 flush_dcache_page(ecryptfs_page); 366 SetPageUptodate(ecryptfs_page); 367 unlock_page(ecryptfs_page); 368 page_cache_release(ecryptfs_page); 369 pos += num_bytes; 370 data_offset += num_bytes; 371 } 372 out: 373 return rc; 374 } 375 #endif /* 0 */ 376