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 *path; 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 path = ecryptfs_dentry_to_lower_path(file->f_path.dentry); 64 touch_atime(path); 65 } 66 return rc; 67 } 68 69 struct ecryptfs_getdents_callback { 70 struct dir_context ctx; 71 struct dir_context *caller; 72 struct super_block *sb; 73 int filldir_called; 74 int entries_written; 75 }; 76 77 /* Inspired by generic filldir in fs/readdir.c */ 78 static int 79 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen, 80 loff_t offset, u64 ino, unsigned int d_type) 81 { 82 struct ecryptfs_getdents_callback *buf = 83 (struct ecryptfs_getdents_callback *)dirent; 84 size_t name_size; 85 char *name; 86 int rc; 87 88 buf->filldir_called++; 89 rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size, 90 buf->sb, lower_name, 91 lower_namelen); 92 if (rc) { 93 printk(KERN_ERR "%s: Error attempting to decode and decrypt " 94 "filename [%s]; rc = [%d]\n", __func__, lower_name, 95 rc); 96 goto out; 97 } 98 buf->caller->pos = buf->ctx.pos; 99 rc = !dir_emit(buf->caller, name, name_size, ino, d_type); 100 kfree(name); 101 if (!rc) 102 buf->entries_written++; 103 out: 104 return rc; 105 } 106 107 /** 108 * ecryptfs_readdir 109 * @file: The eCryptfs directory file 110 * @ctx: The actor to feed the entries to 111 */ 112 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx) 113 { 114 int rc; 115 struct file *lower_file; 116 struct inode *inode = file_inode(file); 117 struct ecryptfs_getdents_callback buf = { 118 .ctx.actor = ecryptfs_filldir, 119 .caller = ctx, 120 .sb = inode->i_sb, 121 }; 122 lower_file = ecryptfs_file_to_lower(file); 123 lower_file->f_pos = ctx->pos; 124 rc = iterate_dir(lower_file, &buf.ctx); 125 ctx->pos = buf.ctx.pos; 126 if (rc < 0) 127 goto out; 128 if (buf.filldir_called && !buf.entries_written) 129 goto out; 130 if (rc >= 0) 131 fsstack_copy_attr_atime(inode, 132 file_inode(lower_file)); 133 out: 134 return rc; 135 } 136 137 struct kmem_cache *ecryptfs_file_info_cache; 138 139 static int read_or_initialize_metadata(struct dentry *dentry) 140 { 141 struct inode *inode = dentry->d_inode; 142 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 143 struct ecryptfs_crypt_stat *crypt_stat; 144 int rc; 145 146 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 147 mount_crypt_stat = &ecryptfs_superblock_to_private( 148 inode->i_sb)->mount_crypt_stat; 149 mutex_lock(&crypt_stat->cs_mutex); 150 151 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && 152 crypt_stat->flags & ECRYPTFS_KEY_VALID) { 153 rc = 0; 154 goto out; 155 } 156 157 rc = ecryptfs_read_metadata(dentry); 158 if (!rc) 159 goto out; 160 161 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { 162 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 163 | ECRYPTFS_ENCRYPTED); 164 rc = 0; 165 goto out; 166 } 167 168 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && 169 !i_size_read(ecryptfs_inode_to_lower(inode))) { 170 rc = ecryptfs_initialize_file(dentry, inode); 171 if (!rc) 172 goto out; 173 } 174 175 rc = -EIO; 176 out: 177 mutex_unlock(&crypt_stat->cs_mutex); 178 return rc; 179 } 180 181 /** 182 * ecryptfs_open 183 * @inode: inode speciying file to open 184 * @file: Structure to return filled in 185 * 186 * Opens the file specified by inode. 187 * 188 * Returns zero on success; non-zero otherwise 189 */ 190 static int ecryptfs_open(struct inode *inode, struct file *file) 191 { 192 int rc = 0; 193 struct ecryptfs_crypt_stat *crypt_stat = NULL; 194 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 195 struct dentry *ecryptfs_dentry = file->f_path.dentry; 196 /* Private value of ecryptfs_dentry allocated in 197 * ecryptfs_lookup() */ 198 struct ecryptfs_file_info *file_info; 199 200 mount_crypt_stat = &ecryptfs_superblock_to_private( 201 ecryptfs_dentry->d_sb)->mount_crypt_stat; 202 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 203 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 204 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 205 || (file->f_flags & O_APPEND))) { 206 printk(KERN_WARNING "Mount has encrypted view enabled; " 207 "files may only be read\n"); 208 rc = -EPERM; 209 goto out; 210 } 211 /* Released in ecryptfs_release or end of function if failure */ 212 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 213 ecryptfs_set_file_private(file, file_info); 214 if (!file_info) { 215 ecryptfs_printk(KERN_ERR, 216 "Error attempting to allocate memory\n"); 217 rc = -ENOMEM; 218 goto out; 219 } 220 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 221 mutex_lock(&crypt_stat->cs_mutex); 222 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 223 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 224 /* Policy code enabled in future release */ 225 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 226 | ECRYPTFS_ENCRYPTED); 227 } 228 mutex_unlock(&crypt_stat->cs_mutex); 229 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 230 if (rc) { 231 printk(KERN_ERR "%s: Error attempting to initialize " 232 "the lower file for the dentry with name " 233 "[%s]; rc = [%d]\n", __func__, 234 ecryptfs_dentry->d_name.name, rc); 235 goto out_free; 236 } 237 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 238 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 239 rc = -EPERM; 240 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 241 "file must hence be opened RO\n", __func__); 242 goto out_put; 243 } 244 ecryptfs_set_file_lower( 245 file, ecryptfs_inode_to_private(inode)->lower_file); 246 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 247 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 248 mutex_lock(&crypt_stat->cs_mutex); 249 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 250 mutex_unlock(&crypt_stat->cs_mutex); 251 rc = 0; 252 goto out; 253 } 254 rc = read_or_initialize_metadata(ecryptfs_dentry); 255 if (rc) 256 goto out_put; 257 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 258 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 259 (unsigned long long)i_size_read(inode)); 260 goto out; 261 out_put: 262 ecryptfs_put_lower_file(inode); 263 out_free: 264 kmem_cache_free(ecryptfs_file_info_cache, 265 ecryptfs_file_to_private(file)); 266 out: 267 return rc; 268 } 269 270 static int ecryptfs_flush(struct file *file, fl_owner_t td) 271 { 272 struct file *lower_file = ecryptfs_file_to_lower(file); 273 274 if (lower_file->f_op->flush) { 275 filemap_write_and_wait(file->f_mapping); 276 return lower_file->f_op->flush(lower_file, td); 277 } 278 279 return 0; 280 } 281 282 static int ecryptfs_release(struct inode *inode, struct file *file) 283 { 284 ecryptfs_put_lower_file(inode); 285 kmem_cache_free(ecryptfs_file_info_cache, 286 ecryptfs_file_to_private(file)); 287 return 0; 288 } 289 290 static int 291 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 292 { 293 int rc; 294 295 rc = filemap_write_and_wait(file->f_mapping); 296 if (rc) 297 return rc; 298 299 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 300 } 301 302 static int ecryptfs_fasync(int fd, struct file *file, int flag) 303 { 304 int rc = 0; 305 struct file *lower_file = NULL; 306 307 lower_file = ecryptfs_file_to_lower(file); 308 if (lower_file->f_op->fasync) 309 rc = lower_file->f_op->fasync(fd, lower_file, flag); 310 return rc; 311 } 312 313 static long 314 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 315 { 316 struct file *lower_file = ecryptfs_file_to_lower(file); 317 long rc = -ENOTTY; 318 319 if (lower_file->f_op->unlocked_ioctl) 320 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 321 return rc; 322 } 323 324 #ifdef CONFIG_COMPAT 325 static long 326 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 327 { 328 struct file *lower_file = ecryptfs_file_to_lower(file); 329 long rc = -ENOIOCTLCMD; 330 331 if (lower_file->f_op && lower_file->f_op->compat_ioctl) 332 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 333 return rc; 334 } 335 #endif 336 337 const struct file_operations ecryptfs_dir_fops = { 338 .iterate = ecryptfs_readdir, 339 .read = generic_read_dir, 340 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 341 #ifdef CONFIG_COMPAT 342 .compat_ioctl = ecryptfs_compat_ioctl, 343 #endif 344 .open = ecryptfs_open, 345 .flush = ecryptfs_flush, 346 .release = ecryptfs_release, 347 .fsync = ecryptfs_fsync, 348 .fasync = ecryptfs_fasync, 349 .splice_read = generic_file_splice_read, 350 .llseek = default_llseek, 351 }; 352 353 const struct file_operations ecryptfs_main_fops = { 354 .llseek = generic_file_llseek, 355 .read = do_sync_read, 356 .aio_read = ecryptfs_read_update_atime, 357 .write = do_sync_write, 358 .aio_write = generic_file_aio_write, 359 .iterate = ecryptfs_readdir, 360 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 361 #ifdef CONFIG_COMPAT 362 .compat_ioctl = ecryptfs_compat_ioctl, 363 #endif 364 .mmap = generic_file_mmap, 365 .open = ecryptfs_open, 366 .flush = ecryptfs_flush, 367 .release = ecryptfs_release, 368 .fsync = ecryptfs_fsync, 369 .fasync = ecryptfs_fasync, 370 .splice_read = generic_file_splice_read, 371 }; 372