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 struct dir_context ctx; 72 struct dir_context *caller; 73 struct super_block *sb; 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->sb, 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 buf->caller->pos = buf->ctx.pos; 100 rc = !dir_emit(buf->caller, name, name_size, ino, d_type); 101 kfree(name); 102 if (!rc) 103 buf->entries_written++; 104 out: 105 return rc; 106 } 107 108 /** 109 * ecryptfs_readdir 110 * @file: The eCryptfs directory file 111 * @ctx: The actor to feed the entries to 112 */ 113 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx) 114 { 115 int rc; 116 struct file *lower_file; 117 struct inode *inode = file_inode(file); 118 struct ecryptfs_getdents_callback buf = { 119 .ctx.actor = ecryptfs_filldir, 120 .caller = ctx, 121 .sb = inode->i_sb, 122 }; 123 lower_file = ecryptfs_file_to_lower(file); 124 lower_file->f_pos = ctx->pos; 125 rc = iterate_dir(lower_file, &buf.ctx); 126 ctx->pos = buf.ctx.pos; 127 if (rc < 0) 128 goto out; 129 if (buf.filldir_called && !buf.entries_written) 130 goto out; 131 if (rc >= 0) 132 fsstack_copy_attr_atime(inode, 133 file_inode(lower_file)); 134 out: 135 return rc; 136 } 137 138 struct kmem_cache *ecryptfs_file_info_cache; 139 140 static int read_or_initialize_metadata(struct dentry *dentry) 141 { 142 struct inode *inode = dentry->d_inode; 143 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 144 struct ecryptfs_crypt_stat *crypt_stat; 145 int rc; 146 147 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 148 mount_crypt_stat = &ecryptfs_superblock_to_private( 149 inode->i_sb)->mount_crypt_stat; 150 mutex_lock(&crypt_stat->cs_mutex); 151 152 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && 153 crypt_stat->flags & ECRYPTFS_KEY_VALID) { 154 rc = 0; 155 goto out; 156 } 157 158 rc = ecryptfs_read_metadata(dentry); 159 if (!rc) 160 goto out; 161 162 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { 163 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 164 | ECRYPTFS_ENCRYPTED); 165 rc = 0; 166 goto out; 167 } 168 169 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && 170 !i_size_read(ecryptfs_inode_to_lower(inode))) { 171 rc = ecryptfs_initialize_file(dentry, inode); 172 if (!rc) 173 goto out; 174 } 175 176 rc = -EIO; 177 out: 178 mutex_unlock(&crypt_stat->cs_mutex); 179 return rc; 180 } 181 182 /** 183 * ecryptfs_open 184 * @inode: inode speciying file to open 185 * @file: Structure to return filled in 186 * 187 * Opens the file specified by inode. 188 * 189 * Returns zero on success; non-zero otherwise 190 */ 191 static int ecryptfs_open(struct inode *inode, struct file *file) 192 { 193 int rc = 0; 194 struct ecryptfs_crypt_stat *crypt_stat = NULL; 195 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 196 struct dentry *ecryptfs_dentry = file->f_path.dentry; 197 /* Private value of ecryptfs_dentry allocated in 198 * ecryptfs_lookup() */ 199 struct ecryptfs_file_info *file_info; 200 201 mount_crypt_stat = &ecryptfs_superblock_to_private( 202 ecryptfs_dentry->d_sb)->mount_crypt_stat; 203 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 204 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 205 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 206 || (file->f_flags & O_APPEND))) { 207 printk(KERN_WARNING "Mount has encrypted view enabled; " 208 "files may only be read\n"); 209 rc = -EPERM; 210 goto out; 211 } 212 /* Released in ecryptfs_release or end of function if failure */ 213 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 214 ecryptfs_set_file_private(file, file_info); 215 if (!file_info) { 216 ecryptfs_printk(KERN_ERR, 217 "Error attempting to allocate memory\n"); 218 rc = -ENOMEM; 219 goto out; 220 } 221 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 222 mutex_lock(&crypt_stat->cs_mutex); 223 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 224 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 225 /* Policy code enabled in future release */ 226 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 227 | ECRYPTFS_ENCRYPTED); 228 } 229 mutex_unlock(&crypt_stat->cs_mutex); 230 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 231 if (rc) { 232 printk(KERN_ERR "%s: Error attempting to initialize " 233 "the lower file for the dentry with name " 234 "[%s]; rc = [%d]\n", __func__, 235 ecryptfs_dentry->d_name.name, rc); 236 goto out_free; 237 } 238 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 239 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 240 rc = -EPERM; 241 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 242 "file must hence be opened RO\n", __func__); 243 goto out_put; 244 } 245 ecryptfs_set_file_lower( 246 file, ecryptfs_inode_to_private(inode)->lower_file); 247 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 248 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 249 mutex_lock(&crypt_stat->cs_mutex); 250 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 251 mutex_unlock(&crypt_stat->cs_mutex); 252 rc = 0; 253 goto out; 254 } 255 rc = read_or_initialize_metadata(ecryptfs_dentry); 256 if (rc) 257 goto out_put; 258 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 259 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 260 (unsigned long long)i_size_read(inode)); 261 goto out; 262 out_put: 263 ecryptfs_put_lower_file(inode); 264 out_free: 265 kmem_cache_free(ecryptfs_file_info_cache, 266 ecryptfs_file_to_private(file)); 267 out: 268 return rc; 269 } 270 271 static int ecryptfs_flush(struct file *file, fl_owner_t td) 272 { 273 struct file *lower_file = ecryptfs_file_to_lower(file); 274 275 if (lower_file->f_op && lower_file->f_op->flush) { 276 filemap_write_and_wait(file->f_mapping); 277 return lower_file->f_op->flush(lower_file, td); 278 } 279 280 return 0; 281 } 282 283 static int ecryptfs_release(struct inode *inode, struct file *file) 284 { 285 ecryptfs_put_lower_file(inode); 286 kmem_cache_free(ecryptfs_file_info_cache, 287 ecryptfs_file_to_private(file)); 288 return 0; 289 } 290 291 static int 292 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 293 { 294 int rc; 295 296 rc = filemap_write_and_wait(file->f_mapping); 297 if (rc) 298 return rc; 299 300 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 301 } 302 303 static int ecryptfs_fasync(int fd, struct file *file, int flag) 304 { 305 int rc = 0; 306 struct file *lower_file = NULL; 307 308 lower_file = ecryptfs_file_to_lower(file); 309 if (lower_file->f_op && lower_file->f_op->fasync) 310 rc = lower_file->f_op->fasync(fd, lower_file, flag); 311 return rc; 312 } 313 314 static long 315 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 316 { 317 struct file *lower_file = NULL; 318 long rc = -ENOTTY; 319 320 if (ecryptfs_file_to_private(file)) 321 lower_file = ecryptfs_file_to_lower(file); 322 if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl) 323 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 324 return rc; 325 } 326 327 #ifdef CONFIG_COMPAT 328 static long 329 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 330 { 331 struct file *lower_file = NULL; 332 long rc = -ENOIOCTLCMD; 333 334 if (ecryptfs_file_to_private(file)) 335 lower_file = ecryptfs_file_to_lower(file); 336 if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl) 337 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 338 return rc; 339 } 340 #endif 341 342 const struct file_operations ecryptfs_dir_fops = { 343 .iterate = ecryptfs_readdir, 344 .read = generic_read_dir, 345 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 346 #ifdef CONFIG_COMPAT 347 .compat_ioctl = ecryptfs_compat_ioctl, 348 #endif 349 .open = ecryptfs_open, 350 .flush = ecryptfs_flush, 351 .release = ecryptfs_release, 352 .fsync = ecryptfs_fsync, 353 .fasync = ecryptfs_fasync, 354 .splice_read = generic_file_splice_read, 355 .llseek = default_llseek, 356 }; 357 358 const struct file_operations ecryptfs_main_fops = { 359 .llseek = generic_file_llseek, 360 .read = do_sync_read, 361 .aio_read = ecryptfs_read_update_atime, 362 .write = do_sync_write, 363 .aio_write = generic_file_aio_write, 364 .iterate = ecryptfs_readdir, 365 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 366 #ifdef CONFIG_COMPAT 367 .compat_ioctl = ecryptfs_compat_ioctl, 368 #endif 369 .mmap = generic_file_mmap, 370 .open = ecryptfs_open, 371 .flush = ecryptfs_flush, 372 .release = ecryptfs_release, 373 .fsync = ecryptfs_fsync, 374 .fasync = ecryptfs_fasync, 375 .splice_read = generic_file_splice_read, 376 }; 377