1 /** 2 * eCryptfs: Linux filesystem encryption layer 3 * 4 * Copyright (C) 1997-2004 Erez Zadok 5 * Copyright (C) 2001-2004 Stony Brook University 6 * Copyright (C) 2004-2007 International Business Machines Corp. 7 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com> 8 * Michael C. Thompson <mcthomps@us.ibm.com> 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License as 12 * published by the Free Software Foundation; either version 2 of the 13 * License, or (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, but 16 * WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 18 * General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License 21 * along with this program; if not, write to the Free Software 22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 23 * 02111-1307, USA. 24 */ 25 26 #include <linux/file.h> 27 #include <linux/poll.h> 28 #include <linux/mount.h> 29 #include <linux/pagemap.h> 30 #include <linux/security.h> 31 #include <linux/compat.h> 32 #include <linux/fs_stack.h> 33 #include "ecryptfs_kernel.h" 34 35 /** 36 * ecryptfs_read_update_atime 37 * 38 * generic_file_read updates the atime of upper layer inode. But, it 39 * doesn't give us a chance to update the atime of the lower layer 40 * inode. This function is a wrapper to generic_file_read. It 41 * updates the atime of the lower level inode if generic_file_read 42 * returns without any errors. This is to be used only for file reads. 43 * The function to be used for directory reads is ecryptfs_read. 44 */ 45 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, 46 const struct iovec *iov, 47 unsigned long nr_segs, loff_t pos) 48 { 49 int rc; 50 struct dentry *lower_dentry; 51 struct vfsmount *lower_vfsmount; 52 struct file *file = iocb->ki_filp; 53 54 rc = generic_file_aio_read(iocb, iov, nr_segs, pos); 55 /* 56 * Even though this is a async interface, we need to wait 57 * for IO to finish to update atime 58 */ 59 if (-EIOCBQUEUED == rc) 60 rc = wait_on_sync_kiocb(iocb); 61 if (rc >= 0) { 62 lower_dentry = ecryptfs_dentry_to_lower(file->f_path.dentry); 63 lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry); 64 touch_atime(lower_vfsmount, lower_dentry); 65 } 66 return rc; 67 } 68 69 struct ecryptfs_getdents_callback { 70 void *dirent; 71 struct dentry *dentry; 72 filldir_t filldir; 73 int err; 74 int filldir_called; 75 int entries_written; 76 }; 77 78 /* Inspired by generic filldir in fs/readir.c */ 79 static int 80 ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset, 81 u64 ino, unsigned int d_type) 82 { 83 struct ecryptfs_crypt_stat *crypt_stat; 84 struct ecryptfs_getdents_callback *buf = 85 (struct ecryptfs_getdents_callback *)dirent; 86 int rc; 87 int decoded_length; 88 char *decoded_name; 89 90 crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat; 91 buf->filldir_called++; 92 decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen, 93 &decoded_name); 94 if (decoded_length < 0) { 95 rc = decoded_length; 96 goto out; 97 } 98 rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset, 99 ino, d_type); 100 kfree(decoded_name); 101 if (rc >= 0) 102 buf->entries_written++; 103 out: 104 return rc; 105 } 106 107 /** 108 * ecryptfs_readdir 109 * @file: The ecryptfs file struct 110 * @dirent: Directory entry 111 * @filldir: The filldir callback function 112 */ 113 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir) 114 { 115 int rc; 116 struct file *lower_file; 117 struct inode *inode; 118 struct ecryptfs_getdents_callback buf; 119 120 lower_file = ecryptfs_file_to_lower(file); 121 lower_file->f_pos = file->f_pos; 122 inode = file->f_path.dentry->d_inode; 123 memset(&buf, 0, sizeof(buf)); 124 buf.dirent = dirent; 125 buf.dentry = file->f_path.dentry; 126 buf.filldir = filldir; 127 retry: 128 buf.filldir_called = 0; 129 buf.entries_written = 0; 130 buf.err = 0; 131 rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf); 132 if (buf.err) 133 rc = buf.err; 134 if (buf.filldir_called && !buf.entries_written) 135 goto retry; 136 file->f_pos = lower_file->f_pos; 137 if (rc >= 0) 138 fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode); 139 return rc; 140 } 141 142 struct kmem_cache *ecryptfs_file_info_cache; 143 144 int ecryptfs_open_lower_file(struct file **lower_file, 145 struct dentry *lower_dentry, 146 struct vfsmount *lower_mnt, int flags) 147 { 148 int rc = 0; 149 150 flags |= O_LARGEFILE; 151 dget(lower_dentry); 152 mntget(lower_mnt); 153 *lower_file = dentry_open(lower_dentry, lower_mnt, flags); 154 if (IS_ERR(*lower_file)) { 155 printk(KERN_ERR "Error opening lower file for lower_dentry " 156 "[0x%p], lower_mnt [0x%p], and flags [0x%x]\n", 157 lower_dentry, lower_mnt, flags); 158 rc = PTR_ERR(*lower_file); 159 *lower_file = NULL; 160 goto out; 161 } 162 out: 163 return rc; 164 } 165 166 int ecryptfs_close_lower_file(struct file *lower_file) 167 { 168 fput(lower_file); 169 return 0; 170 } 171 172 /** 173 * ecryptfs_open 174 * @inode: inode speciying file to open 175 * @file: Structure to return filled in 176 * 177 * Opens the file specified by inode. 178 * 179 * Returns zero on success; non-zero otherwise 180 */ 181 static int ecryptfs_open(struct inode *inode, struct file *file) 182 { 183 int rc = 0; 184 struct ecryptfs_crypt_stat *crypt_stat = NULL; 185 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 186 struct dentry *ecryptfs_dentry = file->f_path.dentry; 187 /* Private value of ecryptfs_dentry allocated in 188 * ecryptfs_lookup() */ 189 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); 190 struct inode *lower_inode = NULL; 191 struct file *lower_file = NULL; 192 struct vfsmount *lower_mnt; 193 struct ecryptfs_file_info *file_info; 194 int lower_flags; 195 196 mount_crypt_stat = &ecryptfs_superblock_to_private( 197 ecryptfs_dentry->d_sb)->mount_crypt_stat; 198 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 199 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 200 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 201 || (file->f_flags & O_APPEND))) { 202 printk(KERN_WARNING "Mount has encrypted view enabled; " 203 "files may only be read\n"); 204 rc = -EPERM; 205 goto out; 206 } 207 /* Released in ecryptfs_release or end of function if failure */ 208 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 209 ecryptfs_set_file_private(file, file_info); 210 if (!file_info) { 211 ecryptfs_printk(KERN_ERR, 212 "Error attempting to allocate memory\n"); 213 rc = -ENOMEM; 214 goto out; 215 } 216 lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); 217 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 218 mutex_lock(&crypt_stat->cs_mutex); 219 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 220 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 221 /* Policy code enabled in future release */ 222 crypt_stat->flags |= ECRYPTFS_POLICY_APPLIED; 223 crypt_stat->flags |= ECRYPTFS_ENCRYPTED; 224 } 225 mutex_unlock(&crypt_stat->cs_mutex); 226 lower_flags = file->f_flags; 227 if ((lower_flags & O_ACCMODE) == O_WRONLY) 228 lower_flags = (lower_flags & O_ACCMODE) | O_RDWR; 229 if (file->f_flags & O_APPEND) 230 lower_flags &= ~O_APPEND; 231 lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry); 232 /* Corresponding fput() in ecryptfs_release() */ 233 if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt, 234 lower_flags))) { 235 ecryptfs_printk(KERN_ERR, "Error opening lower file\n"); 236 goto out_puts; 237 } 238 ecryptfs_set_file_lower(file, lower_file); 239 /* Isn't this check the same as the one in lookup? */ 240 lower_inode = lower_dentry->d_inode; 241 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 242 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 243 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 244 rc = 0; 245 goto out; 246 } 247 mutex_lock(&crypt_stat->cs_mutex); 248 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED) 249 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { 250 rc = ecryptfs_read_metadata(ecryptfs_dentry, lower_file); 251 if (rc) { 252 ecryptfs_printk(KERN_DEBUG, 253 "Valid headers not found\n"); 254 if (!(mount_crypt_stat->flags 255 & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) { 256 rc = -EIO; 257 printk(KERN_WARNING "Attempt to read file that " 258 "is not in a valid eCryptfs format, " 259 "and plaintext passthrough mode is not " 260 "enabled; returning -EIO\n"); 261 mutex_unlock(&crypt_stat->cs_mutex); 262 goto out_puts; 263 } 264 rc = 0; 265 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 266 mutex_unlock(&crypt_stat->cs_mutex); 267 goto out; 268 } 269 } 270 mutex_unlock(&crypt_stat->cs_mutex); 271 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] " 272 "size: [0x%.16x]\n", inode, inode->i_ino, 273 i_size_read(inode)); 274 ecryptfs_set_file_lower(file, lower_file); 275 goto out; 276 out_puts: 277 mntput(lower_mnt); 278 dput(lower_dentry); 279 kmem_cache_free(ecryptfs_file_info_cache, 280 ecryptfs_file_to_private(file)); 281 out: 282 return rc; 283 } 284 285 static int ecryptfs_flush(struct file *file, fl_owner_t td) 286 { 287 int rc = 0; 288 struct file *lower_file = NULL; 289 290 lower_file = ecryptfs_file_to_lower(file); 291 if (lower_file->f_op && lower_file->f_op->flush) 292 rc = lower_file->f_op->flush(lower_file, td); 293 return rc; 294 } 295 296 static int ecryptfs_release(struct inode *inode, struct file *file) 297 { 298 struct file *lower_file = ecryptfs_file_to_lower(file); 299 struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file); 300 struct inode *lower_inode = ecryptfs_inode_to_lower(inode); 301 int rc; 302 303 if ((rc = ecryptfs_close_lower_file(lower_file))) { 304 printk(KERN_ERR "Error closing lower_file\n"); 305 goto out; 306 } 307 inode->i_blocks = lower_inode->i_blocks; 308 kmem_cache_free(ecryptfs_file_info_cache, file_info); 309 out: 310 return rc; 311 } 312 313 static int 314 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync) 315 { 316 struct file *lower_file = ecryptfs_file_to_lower(file); 317 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 318 struct inode *lower_inode = lower_dentry->d_inode; 319 int rc = -EINVAL; 320 321 if (lower_inode->i_fop->fsync) { 322 mutex_lock(&lower_inode->i_mutex); 323 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry, 324 datasync); 325 mutex_unlock(&lower_inode->i_mutex); 326 } 327 return rc; 328 } 329 330 static int ecryptfs_fasync(int fd, struct file *file, int flag) 331 { 332 int rc = 0; 333 struct file *lower_file = NULL; 334 335 lower_file = ecryptfs_file_to_lower(file); 336 if (lower_file->f_op && lower_file->f_op->fasync) 337 rc = lower_file->f_op->fasync(fd, lower_file, flag); 338 return rc; 339 } 340 341 static ssize_t ecryptfs_splice_read(struct file *file, loff_t * ppos, 342 struct pipe_inode_info *pipe, size_t count, 343 unsigned int flags) 344 { 345 struct file *lower_file = NULL; 346 int rc = -EINVAL; 347 348 lower_file = ecryptfs_file_to_lower(file); 349 if (lower_file->f_op && lower_file->f_op->splice_read) 350 rc = lower_file->f_op->splice_read(lower_file, ppos, pipe, 351 count, flags); 352 353 return rc; 354 } 355 356 static int ecryptfs_ioctl(struct inode *inode, struct file *file, 357 unsigned int cmd, unsigned long arg); 358 359 const struct file_operations ecryptfs_dir_fops = { 360 .readdir = ecryptfs_readdir, 361 .ioctl = ecryptfs_ioctl, 362 .mmap = generic_file_mmap, 363 .open = ecryptfs_open, 364 .flush = ecryptfs_flush, 365 .release = ecryptfs_release, 366 .fsync = ecryptfs_fsync, 367 .fasync = ecryptfs_fasync, 368 .splice_read = ecryptfs_splice_read, 369 }; 370 371 const struct file_operations ecryptfs_main_fops = { 372 .llseek = generic_file_llseek, 373 .read = do_sync_read, 374 .aio_read = ecryptfs_read_update_atime, 375 .write = do_sync_write, 376 .aio_write = generic_file_aio_write, 377 .readdir = ecryptfs_readdir, 378 .ioctl = ecryptfs_ioctl, 379 .mmap = generic_file_mmap, 380 .open = ecryptfs_open, 381 .flush = ecryptfs_flush, 382 .release = ecryptfs_release, 383 .fsync = ecryptfs_fsync, 384 .fasync = ecryptfs_fasync, 385 .splice_read = ecryptfs_splice_read, 386 }; 387 388 static int 389 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 390 unsigned long arg) 391 { 392 int rc = 0; 393 struct file *lower_file = NULL; 394 395 if (ecryptfs_file_to_private(file)) 396 lower_file = ecryptfs_file_to_lower(file); 397 if (lower_file && lower_file->f_op && lower_file->f_op->ioctl) 398 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode), 399 lower_file, cmd, arg); 400 else 401 rc = -ENOTTY; 402 return rc; 403 } 404