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/slab.h> 29 #include <linux/mount.h> 30 #include <linux/pagemap.h> 31 #include <linux/security.h> 32 #include <linux/compat.h> 33 #include <linux/fs_stack.h> 34 #include <linux/aio.h> 35 #include "ecryptfs_kernel.h" 36 37 /** 38 * ecryptfs_read_update_atime 39 * 40 * generic_file_read updates the atime of upper layer inode. But, it 41 * doesn't give us a chance to update the atime of the lower layer 42 * inode. This function is a wrapper to generic_file_read. It 43 * updates the atime of the lower level inode if generic_file_read 44 * returns without any errors. This is to be used only for file reads. 45 * The function to be used for directory reads is ecryptfs_read. 46 */ 47 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, 48 const struct iovec *iov, 49 unsigned long nr_segs, loff_t pos) 50 { 51 ssize_t rc; 52 struct path lower; 53 struct file *file = iocb->ki_filp; 54 55 rc = generic_file_aio_read(iocb, iov, nr_segs, pos); 56 /* 57 * Even though this is a async interface, we need to wait 58 * for IO to finish to update atime 59 */ 60 if (-EIOCBQUEUED == rc) 61 rc = wait_on_sync_kiocb(iocb); 62 if (rc >= 0) { 63 lower.dentry = ecryptfs_dentry_to_lower(file->f_path.dentry); 64 lower.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry); 65 touch_atime(&lower); 66 } 67 return rc; 68 } 69 70 struct ecryptfs_getdents_callback { 71 void *dirent; 72 struct dentry *dentry; 73 filldir_t filldir; 74 int filldir_called; 75 int entries_written; 76 }; 77 78 /* Inspired by generic filldir in fs/readdir.c */ 79 static int 80 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen, 81 loff_t offset, u64 ino, unsigned int d_type) 82 { 83 struct ecryptfs_getdents_callback *buf = 84 (struct ecryptfs_getdents_callback *)dirent; 85 size_t name_size; 86 char *name; 87 int rc; 88 89 buf->filldir_called++; 90 rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size, 91 buf->dentry, lower_name, 92 lower_namelen); 93 if (rc) { 94 printk(KERN_ERR "%s: Error attempting to decode and decrypt " 95 "filename [%s]; rc = [%d]\n", __func__, lower_name, 96 rc); 97 goto out; 98 } 99 rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type); 100 kfree(name); 101 if (rc >= 0) 102 buf->entries_written++; 103 out: 104 return rc; 105 } 106 107 /** 108 * ecryptfs_readdir 109 * @file: The eCryptfs directory file 110 * @dirent: Directory entry handle 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_inode(file); 123 memset(&buf, 0, sizeof(buf)); 124 buf.dirent = dirent; 125 buf.dentry = file->f_path.dentry; 126 buf.filldir = filldir; 127 buf.filldir_called = 0; 128 buf.entries_written = 0; 129 rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf); 130 file->f_pos = lower_file->f_pos; 131 if (rc < 0) 132 goto out; 133 if (buf.filldir_called && !buf.entries_written) 134 goto out; 135 if (rc >= 0) 136 fsstack_copy_attr_atime(inode, 137 file_inode(lower_file)); 138 out: 139 return rc; 140 } 141 142 struct kmem_cache *ecryptfs_file_info_cache; 143 144 static int read_or_initialize_metadata(struct dentry *dentry) 145 { 146 struct inode *inode = dentry->d_inode; 147 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 148 struct ecryptfs_crypt_stat *crypt_stat; 149 int rc; 150 151 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 152 mount_crypt_stat = &ecryptfs_superblock_to_private( 153 inode->i_sb)->mount_crypt_stat; 154 mutex_lock(&crypt_stat->cs_mutex); 155 156 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && 157 crypt_stat->flags & ECRYPTFS_KEY_VALID) { 158 rc = 0; 159 goto out; 160 } 161 162 rc = ecryptfs_read_metadata(dentry); 163 if (!rc) 164 goto out; 165 166 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { 167 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 168 | ECRYPTFS_ENCRYPTED); 169 rc = 0; 170 goto out; 171 } 172 173 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && 174 !i_size_read(ecryptfs_inode_to_lower(inode))) { 175 rc = ecryptfs_initialize_file(dentry, inode); 176 if (!rc) 177 goto out; 178 } 179 180 rc = -EIO; 181 out: 182 mutex_unlock(&crypt_stat->cs_mutex); 183 return rc; 184 } 185 186 /** 187 * ecryptfs_open 188 * @inode: inode speciying file to open 189 * @file: Structure to return filled in 190 * 191 * Opens the file specified by inode. 192 * 193 * Returns zero on success; non-zero otherwise 194 */ 195 static int ecryptfs_open(struct inode *inode, struct file *file) 196 { 197 int rc = 0; 198 struct ecryptfs_crypt_stat *crypt_stat = NULL; 199 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 200 struct dentry *ecryptfs_dentry = file->f_path.dentry; 201 /* Private value of ecryptfs_dentry allocated in 202 * ecryptfs_lookup() */ 203 struct ecryptfs_file_info *file_info; 204 205 mount_crypt_stat = &ecryptfs_superblock_to_private( 206 ecryptfs_dentry->d_sb)->mount_crypt_stat; 207 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 208 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 209 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 210 || (file->f_flags & O_APPEND))) { 211 printk(KERN_WARNING "Mount has encrypted view enabled; " 212 "files may only be read\n"); 213 rc = -EPERM; 214 goto out; 215 } 216 /* Released in ecryptfs_release or end of function if failure */ 217 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 218 ecryptfs_set_file_private(file, file_info); 219 if (!file_info) { 220 ecryptfs_printk(KERN_ERR, 221 "Error attempting to allocate memory\n"); 222 rc = -ENOMEM; 223 goto out; 224 } 225 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 226 mutex_lock(&crypt_stat->cs_mutex); 227 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 228 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 229 /* Policy code enabled in future release */ 230 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 231 | ECRYPTFS_ENCRYPTED); 232 } 233 mutex_unlock(&crypt_stat->cs_mutex); 234 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 235 if (rc) { 236 printk(KERN_ERR "%s: Error attempting to initialize " 237 "the lower file for the dentry with name " 238 "[%s]; rc = [%d]\n", __func__, 239 ecryptfs_dentry->d_name.name, rc); 240 goto out_free; 241 } 242 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 243 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 244 rc = -EPERM; 245 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 246 "file must hence be opened RO\n", __func__); 247 goto out_put; 248 } 249 ecryptfs_set_file_lower( 250 file, ecryptfs_inode_to_private(inode)->lower_file); 251 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 252 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 253 mutex_lock(&crypt_stat->cs_mutex); 254 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 255 mutex_unlock(&crypt_stat->cs_mutex); 256 rc = 0; 257 goto out; 258 } 259 rc = read_or_initialize_metadata(ecryptfs_dentry); 260 if (rc) 261 goto out_put; 262 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 263 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 264 (unsigned long long)i_size_read(inode)); 265 goto out; 266 out_put: 267 ecryptfs_put_lower_file(inode); 268 out_free: 269 kmem_cache_free(ecryptfs_file_info_cache, 270 ecryptfs_file_to_private(file)); 271 out: 272 return rc; 273 } 274 275 static int ecryptfs_flush(struct file *file, fl_owner_t td) 276 { 277 struct file *lower_file = ecryptfs_file_to_lower(file); 278 279 if (lower_file->f_op && lower_file->f_op->flush) { 280 filemap_write_and_wait(file->f_mapping); 281 return lower_file->f_op->flush(lower_file, td); 282 } 283 284 return 0; 285 } 286 287 static int ecryptfs_release(struct inode *inode, struct file *file) 288 { 289 ecryptfs_put_lower_file(inode); 290 kmem_cache_free(ecryptfs_file_info_cache, 291 ecryptfs_file_to_private(file)); 292 return 0; 293 } 294 295 static int 296 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 297 { 298 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 299 } 300 301 static int ecryptfs_fasync(int fd, struct file *file, int flag) 302 { 303 int rc = 0; 304 struct file *lower_file = NULL; 305 306 lower_file = ecryptfs_file_to_lower(file); 307 if (lower_file->f_op && lower_file->f_op->fasync) 308 rc = lower_file->f_op->fasync(fd, lower_file, flag); 309 return rc; 310 } 311 312 static long 313 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 314 { 315 struct file *lower_file = NULL; 316 long rc = -ENOTTY; 317 318 if (ecryptfs_file_to_private(file)) 319 lower_file = ecryptfs_file_to_lower(file); 320 if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl) 321 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 322 return rc; 323 } 324 325 #ifdef CONFIG_COMPAT 326 static long 327 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 328 { 329 struct file *lower_file = NULL; 330 long rc = -ENOIOCTLCMD; 331 332 if (ecryptfs_file_to_private(file)) 333 lower_file = ecryptfs_file_to_lower(file); 334 if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl) 335 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 336 return rc; 337 } 338 #endif 339 340 const struct file_operations ecryptfs_dir_fops = { 341 .readdir = ecryptfs_readdir, 342 .read = generic_read_dir, 343 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 344 #ifdef CONFIG_COMPAT 345 .compat_ioctl = ecryptfs_compat_ioctl, 346 #endif 347 .open = ecryptfs_open, 348 .flush = ecryptfs_flush, 349 .release = ecryptfs_release, 350 .fsync = ecryptfs_fsync, 351 .fasync = ecryptfs_fasync, 352 .splice_read = generic_file_splice_read, 353 .llseek = default_llseek, 354 }; 355 356 const struct file_operations ecryptfs_main_fops = { 357 .llseek = generic_file_llseek, 358 .read = do_sync_read, 359 .aio_read = ecryptfs_read_update_atime, 360 .write = do_sync_write, 361 .aio_write = generic_file_aio_write, 362 .readdir = ecryptfs_readdir, 363 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 364 #ifdef CONFIG_COMPAT 365 .compat_ioctl = ecryptfs_compat_ioctl, 366 #endif 367 .mmap = generic_file_mmap, 368 .open = ecryptfs_open, 369 .flush = ecryptfs_flush, 370 .release = ecryptfs_release, 371 .fsync = ecryptfs_fsync, 372 .fasync = ecryptfs_fasync, 373 .splice_read = generic_file_splice_read, 374 }; 375