1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * eCryptfs: Linux filesystem encryption layer 4 * 5 * Copyright (C) 1997-2004 Erez Zadok 6 * Copyright (C) 2001-2004 Stony Brook University 7 * Copyright (C) 2004-2007 International Business Machines Corp. 8 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com> 9 * Michael C. Thompson <mcthomps@us.ibm.com> 10 */ 11 12 #include <linux/file.h> 13 #include <linux/poll.h> 14 #include <linux/slab.h> 15 #include <linux/mount.h> 16 #include <linux/pagemap.h> 17 #include <linux/security.h> 18 #include <linux/compat.h> 19 #include <linux/fs_stack.h> 20 #include "ecryptfs_kernel.h" 21 22 /* 23 * ecryptfs_read_update_atime 24 * 25 * generic_file_read updates the atime of upper layer inode. But, it 26 * doesn't give us a chance to update the atime of the lower layer 27 * inode. This function is a wrapper to generic_file_read. It 28 * updates the atime of the lower level inode if generic_file_read 29 * returns without any errors. This is to be used only for file reads. 30 * The function to be used for directory reads is ecryptfs_read. 31 */ 32 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, 33 struct iov_iter *to) 34 { 35 ssize_t rc; 36 const struct path *path; 37 struct file *file = iocb->ki_filp; 38 39 rc = generic_file_read_iter(iocb, to); 40 if (rc >= 0) { 41 path = ecryptfs_dentry_to_lower_path(file->f_path.dentry); 42 touch_atime(path); 43 } 44 return rc; 45 } 46 47 /* 48 * ecryptfs_splice_read_update_atime 49 * 50 * filemap_splice_read updates the atime of upper layer inode. But, it 51 * doesn't give us a chance to update the atime of the lower layer inode. This 52 * function is a wrapper to generic_file_read. It updates the atime of the 53 * lower level inode if generic_file_read returns without any errors. This is 54 * to be used only for file reads. The function to be used for directory reads 55 * is ecryptfs_read. 56 */ 57 static ssize_t ecryptfs_splice_read_update_atime(struct file *in, loff_t *ppos, 58 struct pipe_inode_info *pipe, 59 size_t len, unsigned int flags) 60 { 61 ssize_t rc; 62 const struct path *path; 63 64 rc = filemap_splice_read(in, ppos, pipe, len, flags); 65 if (rc >= 0) { 66 path = ecryptfs_dentry_to_lower_path(in->f_path.dentry); 67 touch_atime(path); 68 } 69 return rc; 70 } 71 72 struct ecryptfs_getdents_callback { 73 struct dir_context ctx; 74 struct dir_context *caller; 75 struct super_block *sb; 76 int filldir_called; 77 int entries_written; 78 }; 79 80 /* Inspired by generic filldir in fs/readdir.c */ 81 static bool 82 ecryptfs_filldir(struct dir_context *ctx, const char *lower_name, 83 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type) 84 { 85 struct ecryptfs_getdents_callback *buf = 86 container_of(ctx, struct ecryptfs_getdents_callback, ctx); 87 size_t name_size; 88 char *name; 89 int err; 90 bool res; 91 92 buf->filldir_called++; 93 err = ecryptfs_decode_and_decrypt_filename(&name, &name_size, 94 buf->sb, lower_name, 95 lower_namelen); 96 if (err) { 97 if (err != -EINVAL) { 98 ecryptfs_printk(KERN_DEBUG, 99 "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n", 100 __func__, lower_name, err); 101 return false; 102 } 103 104 /* Mask -EINVAL errors as these are most likely due a plaintext 105 * filename present in the lower filesystem despite filename 106 * encryption being enabled. One unavoidable example would be 107 * the "lost+found" dentry in the root directory of an Ext4 108 * filesystem. 109 */ 110 return true; 111 } 112 113 buf->caller->pos = buf->ctx.pos; 114 res = dir_emit(buf->caller, name, name_size, ino, d_type); 115 kfree(name); 116 if (res) 117 buf->entries_written++; 118 return res; 119 } 120 121 /** 122 * ecryptfs_readdir 123 * @file: The eCryptfs directory file 124 * @ctx: The actor to feed the entries to 125 */ 126 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx) 127 { 128 int rc; 129 struct file *lower_file; 130 struct inode *inode = file_inode(file); 131 struct ecryptfs_getdents_callback buf = { 132 .ctx.actor = ecryptfs_filldir, 133 .caller = ctx, 134 .sb = inode->i_sb, 135 }; 136 lower_file = ecryptfs_file_to_lower(file); 137 rc = iterate_dir(lower_file, &buf.ctx); 138 ctx->pos = buf.ctx.pos; 139 if (rc >= 0 && (buf.entries_written || !buf.filldir_called)) 140 fsstack_copy_attr_atime(inode, file_inode(lower_file)); 141 return rc; 142 } 143 144 struct kmem_cache *ecryptfs_file_info_cache; 145 146 static int read_or_initialize_metadata(struct dentry *dentry) 147 { 148 struct inode *inode = d_inode(dentry); 149 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 150 struct ecryptfs_crypt_stat *crypt_stat; 151 int rc; 152 153 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 154 mount_crypt_stat = &ecryptfs_superblock_to_private( 155 inode->i_sb)->mount_crypt_stat; 156 mutex_lock(&crypt_stat->cs_mutex); 157 158 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && 159 crypt_stat->flags & ECRYPTFS_KEY_VALID) { 160 rc = 0; 161 goto out; 162 } 163 164 rc = ecryptfs_read_metadata(dentry); 165 if (!rc) 166 goto out; 167 168 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { 169 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 170 | ECRYPTFS_ENCRYPTED); 171 rc = 0; 172 goto out; 173 } 174 175 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && 176 !i_size_read(ecryptfs_inode_to_lower(inode))) { 177 rc = ecryptfs_initialize_file(dentry, inode); 178 if (!rc) 179 goto out; 180 } 181 182 rc = -EIO; 183 out: 184 mutex_unlock(&crypt_stat->cs_mutex); 185 return rc; 186 } 187 188 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma) 189 { 190 struct file *lower_file = ecryptfs_file_to_lower(file); 191 /* 192 * Don't allow mmap on top of file systems that don't support it 193 * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs 194 * allows recursive mounting, this will need to be extended. 195 */ 196 if (!lower_file->f_op->mmap) 197 return -ENODEV; 198 return generic_file_mmap(file, vma); 199 } 200 201 /** 202 * ecryptfs_open 203 * @inode: inode specifying file to open 204 * @file: Structure to return filled in 205 * 206 * Opens the file specified by inode. 207 * 208 * Returns zero on success; non-zero otherwise 209 */ 210 static int ecryptfs_open(struct inode *inode, struct file *file) 211 { 212 int rc = 0; 213 struct ecryptfs_crypt_stat *crypt_stat = NULL; 214 struct dentry *ecryptfs_dentry = file->f_path.dentry; 215 /* Private value of ecryptfs_dentry allocated in 216 * ecryptfs_lookup() */ 217 struct ecryptfs_file_info *file_info; 218 219 /* Released in ecryptfs_release or end of function if failure */ 220 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 221 ecryptfs_set_file_private(file, file_info); 222 if (!file_info) { 223 ecryptfs_printk(KERN_ERR, 224 "Error attempting to allocate memory\n"); 225 rc = -ENOMEM; 226 goto out; 227 } 228 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 229 mutex_lock(&crypt_stat->cs_mutex); 230 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 231 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 232 /* Policy code enabled in future release */ 233 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 234 | ECRYPTFS_ENCRYPTED); 235 } 236 mutex_unlock(&crypt_stat->cs_mutex); 237 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 238 if (rc) { 239 printk(KERN_ERR "%s: Error attempting to initialize " 240 "the lower file for the dentry with name " 241 "[%pd]; rc = [%d]\n", __func__, 242 ecryptfs_dentry, rc); 243 goto out_free; 244 } 245 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 246 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 247 rc = -EPERM; 248 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 249 "file must hence be opened RO\n", __func__); 250 goto out_put; 251 } 252 ecryptfs_set_file_lower( 253 file, ecryptfs_inode_to_private(inode)->lower_file); 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 /** 271 * ecryptfs_dir_open 272 * @inode: inode specifying file to open 273 * @file: Structure to return filled in 274 * 275 * Opens the file specified by inode. 276 * 277 * Returns zero on success; non-zero otherwise 278 */ 279 static int ecryptfs_dir_open(struct inode *inode, struct file *file) 280 { 281 struct dentry *ecryptfs_dentry = file->f_path.dentry; 282 /* Private value of ecryptfs_dentry allocated in 283 * ecryptfs_lookup() */ 284 struct ecryptfs_file_info *file_info; 285 struct file *lower_file; 286 287 /* Released in ecryptfs_release or end of function if failure */ 288 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 289 ecryptfs_set_file_private(file, file_info); 290 if (unlikely(!file_info)) { 291 ecryptfs_printk(KERN_ERR, 292 "Error attempting to allocate memory\n"); 293 return -ENOMEM; 294 } 295 lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry), 296 file->f_flags, current_cred()); 297 if (IS_ERR(lower_file)) { 298 printk(KERN_ERR "%s: Error attempting to initialize " 299 "the lower file for the dentry with name " 300 "[%pd]; rc = [%ld]\n", __func__, 301 ecryptfs_dentry, PTR_ERR(lower_file)); 302 kmem_cache_free(ecryptfs_file_info_cache, file_info); 303 return PTR_ERR(lower_file); 304 } 305 ecryptfs_set_file_lower(file, lower_file); 306 return 0; 307 } 308 309 static int ecryptfs_flush(struct file *file, fl_owner_t td) 310 { 311 struct file *lower_file = ecryptfs_file_to_lower(file); 312 313 if (lower_file->f_op->flush) { 314 filemap_write_and_wait(file->f_mapping); 315 return lower_file->f_op->flush(lower_file, td); 316 } 317 318 return 0; 319 } 320 321 static int ecryptfs_release(struct inode *inode, struct file *file) 322 { 323 ecryptfs_put_lower_file(inode); 324 kmem_cache_free(ecryptfs_file_info_cache, 325 ecryptfs_file_to_private(file)); 326 return 0; 327 } 328 329 static int ecryptfs_dir_release(struct inode *inode, struct file *file) 330 { 331 fput(ecryptfs_file_to_lower(file)); 332 kmem_cache_free(ecryptfs_file_info_cache, 333 ecryptfs_file_to_private(file)); 334 return 0; 335 } 336 337 static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence) 338 { 339 return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence); 340 } 341 342 static int 343 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 344 { 345 int rc; 346 347 rc = file_write_and_wait(file); 348 if (rc) 349 return rc; 350 351 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 352 } 353 354 static int ecryptfs_fasync(int fd, struct file *file, int flag) 355 { 356 int rc = 0; 357 struct file *lower_file = NULL; 358 359 lower_file = ecryptfs_file_to_lower(file); 360 if (lower_file->f_op->fasync) 361 rc = lower_file->f_op->fasync(fd, lower_file, flag); 362 return rc; 363 } 364 365 static long 366 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 367 { 368 struct file *lower_file = ecryptfs_file_to_lower(file); 369 long rc = -ENOTTY; 370 371 if (!lower_file->f_op->unlocked_ioctl) 372 return rc; 373 374 switch (cmd) { 375 case FITRIM: 376 case FS_IOC_GETFLAGS: 377 case FS_IOC_SETFLAGS: 378 case FS_IOC_GETVERSION: 379 case FS_IOC_SETVERSION: 380 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 381 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); 382 383 return rc; 384 default: 385 return rc; 386 } 387 } 388 389 #ifdef CONFIG_COMPAT 390 static long 391 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 392 { 393 struct file *lower_file = ecryptfs_file_to_lower(file); 394 long rc = -ENOIOCTLCMD; 395 396 if (!lower_file->f_op->compat_ioctl) 397 return rc; 398 399 switch (cmd) { 400 case FITRIM: 401 case FS_IOC32_GETFLAGS: 402 case FS_IOC32_SETFLAGS: 403 case FS_IOC32_GETVERSION: 404 case FS_IOC32_SETVERSION: 405 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 406 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); 407 408 return rc; 409 default: 410 return rc; 411 } 412 } 413 #endif 414 415 const struct file_operations ecryptfs_dir_fops = { 416 .iterate_shared = ecryptfs_readdir, 417 .read = generic_read_dir, 418 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 419 #ifdef CONFIG_COMPAT 420 .compat_ioctl = ecryptfs_compat_ioctl, 421 #endif 422 .open = ecryptfs_dir_open, 423 .release = ecryptfs_dir_release, 424 .fsync = ecryptfs_fsync, 425 .llseek = ecryptfs_dir_llseek, 426 }; 427 428 const struct file_operations ecryptfs_main_fops = { 429 .llseek = generic_file_llseek, 430 .read_iter = ecryptfs_read_update_atime, 431 .write_iter = generic_file_write_iter, 432 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 433 #ifdef CONFIG_COMPAT 434 .compat_ioctl = ecryptfs_compat_ioctl, 435 #endif 436 .mmap = ecryptfs_mmap, 437 .open = ecryptfs_open, 438 .flush = ecryptfs_flush, 439 .release = ecryptfs_release, 440 .fsync = ecryptfs_fsync, 441 .fasync = ecryptfs_fasync, 442 .splice_read = ecryptfs_splice_read_update_atime, 443 }; 444