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 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 struct ecryptfs_getdents_callback { 48 struct dir_context ctx; 49 struct dir_context *caller; 50 struct super_block *sb; 51 int filldir_called; 52 int entries_written; 53 }; 54 55 /* Inspired by generic filldir in fs/readdir.c */ 56 static int 57 ecryptfs_filldir(struct dir_context *ctx, const char *lower_name, 58 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type) 59 { 60 struct ecryptfs_getdents_callback *buf = 61 container_of(ctx, struct ecryptfs_getdents_callback, ctx); 62 size_t name_size; 63 char *name; 64 int rc; 65 66 buf->filldir_called++; 67 rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size, 68 buf->sb, lower_name, 69 lower_namelen); 70 if (rc) { 71 if (rc != -EINVAL) { 72 ecryptfs_printk(KERN_DEBUG, 73 "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n", 74 __func__, lower_name, rc); 75 return rc; 76 } 77 78 /* Mask -EINVAL errors as these are most likely due a plaintext 79 * filename present in the lower filesystem despite filename 80 * encryption being enabled. One unavoidable example would be 81 * the "lost+found" dentry in the root directory of an Ext4 82 * filesystem. 83 */ 84 return 0; 85 } 86 87 buf->caller->pos = buf->ctx.pos; 88 rc = !dir_emit(buf->caller, name, name_size, ino, d_type); 89 kfree(name); 90 if (!rc) 91 buf->entries_written++; 92 93 return rc; 94 } 95 96 /** 97 * ecryptfs_readdir 98 * @file: The eCryptfs directory file 99 * @ctx: The actor to feed the entries to 100 */ 101 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx) 102 { 103 int rc; 104 struct file *lower_file; 105 struct inode *inode = file_inode(file); 106 struct ecryptfs_getdents_callback buf = { 107 .ctx.actor = ecryptfs_filldir, 108 .caller = ctx, 109 .sb = inode->i_sb, 110 }; 111 lower_file = ecryptfs_file_to_lower(file); 112 rc = iterate_dir(lower_file, &buf.ctx); 113 ctx->pos = buf.ctx.pos; 114 if (rc < 0) 115 goto out; 116 if (buf.filldir_called && !buf.entries_written) 117 goto out; 118 if (rc >= 0) 119 fsstack_copy_attr_atime(inode, 120 file_inode(lower_file)); 121 out: 122 return rc; 123 } 124 125 struct kmem_cache *ecryptfs_file_info_cache; 126 127 static int read_or_initialize_metadata(struct dentry *dentry) 128 { 129 struct inode *inode = d_inode(dentry); 130 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 131 struct ecryptfs_crypt_stat *crypt_stat; 132 int rc; 133 134 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 135 mount_crypt_stat = &ecryptfs_superblock_to_private( 136 inode->i_sb)->mount_crypt_stat; 137 mutex_lock(&crypt_stat->cs_mutex); 138 139 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && 140 crypt_stat->flags & ECRYPTFS_KEY_VALID) { 141 rc = 0; 142 goto out; 143 } 144 145 rc = ecryptfs_read_metadata(dentry); 146 if (!rc) 147 goto out; 148 149 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { 150 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 151 | ECRYPTFS_ENCRYPTED); 152 rc = 0; 153 goto out; 154 } 155 156 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && 157 !i_size_read(ecryptfs_inode_to_lower(inode))) { 158 rc = ecryptfs_initialize_file(dentry, inode); 159 if (!rc) 160 goto out; 161 } 162 163 rc = -EIO; 164 out: 165 mutex_unlock(&crypt_stat->cs_mutex); 166 return rc; 167 } 168 169 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma) 170 { 171 struct file *lower_file = ecryptfs_file_to_lower(file); 172 /* 173 * Don't allow mmap on top of file systems that don't support it 174 * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs 175 * allows recursive mounting, this will need to be extended. 176 */ 177 if (!lower_file->f_op->mmap) 178 return -ENODEV; 179 return generic_file_mmap(file, vma); 180 } 181 182 /** 183 * ecryptfs_open 184 * @inode: inode specifying 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 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 /* Released in ecryptfs_release or end of function if failure */ 201 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 202 ecryptfs_set_file_private(file, file_info); 203 if (!file_info) { 204 ecryptfs_printk(KERN_ERR, 205 "Error attempting to allocate memory\n"); 206 rc = -ENOMEM; 207 goto out; 208 } 209 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 210 mutex_lock(&crypt_stat->cs_mutex); 211 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 212 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 213 /* Policy code enabled in future release */ 214 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 215 | ECRYPTFS_ENCRYPTED); 216 } 217 mutex_unlock(&crypt_stat->cs_mutex); 218 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 219 if (rc) { 220 printk(KERN_ERR "%s: Error attempting to initialize " 221 "the lower file for the dentry with name " 222 "[%pd]; rc = [%d]\n", __func__, 223 ecryptfs_dentry, rc); 224 goto out_free; 225 } 226 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 227 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 228 rc = -EPERM; 229 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 230 "file must hence be opened RO\n", __func__); 231 goto out_put; 232 } 233 ecryptfs_set_file_lower( 234 file, ecryptfs_inode_to_private(inode)->lower_file); 235 rc = read_or_initialize_metadata(ecryptfs_dentry); 236 if (rc) 237 goto out_put; 238 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 239 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 240 (unsigned long long)i_size_read(inode)); 241 goto out; 242 out_put: 243 ecryptfs_put_lower_file(inode); 244 out_free: 245 kmem_cache_free(ecryptfs_file_info_cache, 246 ecryptfs_file_to_private(file)); 247 out: 248 return rc; 249 } 250 251 /** 252 * ecryptfs_dir_open 253 * @inode: inode specifying file to open 254 * @file: Structure to return filled in 255 * 256 * Opens the file specified by inode. 257 * 258 * Returns zero on success; non-zero otherwise 259 */ 260 static int ecryptfs_dir_open(struct inode *inode, struct file *file) 261 { 262 struct dentry *ecryptfs_dentry = file->f_path.dentry; 263 /* Private value of ecryptfs_dentry allocated in 264 * ecryptfs_lookup() */ 265 struct ecryptfs_file_info *file_info; 266 struct file *lower_file; 267 268 /* Released in ecryptfs_release or end of function if failure */ 269 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 270 ecryptfs_set_file_private(file, file_info); 271 if (unlikely(!file_info)) { 272 ecryptfs_printk(KERN_ERR, 273 "Error attempting to allocate memory\n"); 274 return -ENOMEM; 275 } 276 lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry), 277 file->f_flags, current_cred()); 278 if (IS_ERR(lower_file)) { 279 printk(KERN_ERR "%s: Error attempting to initialize " 280 "the lower file for the dentry with name " 281 "[%pd]; rc = [%ld]\n", __func__, 282 ecryptfs_dentry, PTR_ERR(lower_file)); 283 kmem_cache_free(ecryptfs_file_info_cache, file_info); 284 return PTR_ERR(lower_file); 285 } 286 ecryptfs_set_file_lower(file, lower_file); 287 return 0; 288 } 289 290 static int ecryptfs_flush(struct file *file, fl_owner_t td) 291 { 292 struct file *lower_file = ecryptfs_file_to_lower(file); 293 294 if (lower_file->f_op->flush) { 295 filemap_write_and_wait(file->f_mapping); 296 return lower_file->f_op->flush(lower_file, td); 297 } 298 299 return 0; 300 } 301 302 static int ecryptfs_release(struct inode *inode, struct file *file) 303 { 304 ecryptfs_put_lower_file(inode); 305 kmem_cache_free(ecryptfs_file_info_cache, 306 ecryptfs_file_to_private(file)); 307 return 0; 308 } 309 310 static int ecryptfs_dir_release(struct inode *inode, struct file *file) 311 { 312 fput(ecryptfs_file_to_lower(file)); 313 kmem_cache_free(ecryptfs_file_info_cache, 314 ecryptfs_file_to_private(file)); 315 return 0; 316 } 317 318 static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence) 319 { 320 return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence); 321 } 322 323 static int 324 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 325 { 326 int rc; 327 328 rc = file_write_and_wait(file); 329 if (rc) 330 return rc; 331 332 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 333 } 334 335 static int ecryptfs_fasync(int fd, struct file *file, int flag) 336 { 337 int rc = 0; 338 struct file *lower_file = NULL; 339 340 lower_file = ecryptfs_file_to_lower(file); 341 if (lower_file->f_op->fasync) 342 rc = lower_file->f_op->fasync(fd, lower_file, flag); 343 return rc; 344 } 345 346 static long 347 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 348 { 349 struct file *lower_file = ecryptfs_file_to_lower(file); 350 long rc = -ENOTTY; 351 352 if (!lower_file->f_op->unlocked_ioctl) 353 return rc; 354 355 switch (cmd) { 356 case FITRIM: 357 case FS_IOC_GETFLAGS: 358 case FS_IOC_SETFLAGS: 359 case FS_IOC_GETVERSION: 360 case FS_IOC_SETVERSION: 361 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 362 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); 363 364 return rc; 365 default: 366 return rc; 367 } 368 } 369 370 #ifdef CONFIG_COMPAT 371 static long 372 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 373 { 374 struct file *lower_file = ecryptfs_file_to_lower(file); 375 long rc = -ENOIOCTLCMD; 376 377 if (!lower_file->f_op->compat_ioctl) 378 return rc; 379 380 switch (cmd) { 381 case FS_IOC32_GETFLAGS: 382 case FS_IOC32_SETFLAGS: 383 case FS_IOC32_GETVERSION: 384 case FS_IOC32_SETVERSION: 385 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 386 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); 387 388 return rc; 389 default: 390 return rc; 391 } 392 } 393 #endif 394 395 const struct file_operations ecryptfs_dir_fops = { 396 .iterate_shared = ecryptfs_readdir, 397 .read = generic_read_dir, 398 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 399 #ifdef CONFIG_COMPAT 400 .compat_ioctl = ecryptfs_compat_ioctl, 401 #endif 402 .open = ecryptfs_dir_open, 403 .release = ecryptfs_dir_release, 404 .fsync = ecryptfs_fsync, 405 .llseek = ecryptfs_dir_llseek, 406 }; 407 408 const struct file_operations ecryptfs_main_fops = { 409 .llseek = generic_file_llseek, 410 .read_iter = ecryptfs_read_update_atime, 411 .write_iter = generic_file_write_iter, 412 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 413 #ifdef CONFIG_COMPAT 414 .compat_ioctl = ecryptfs_compat_ioctl, 415 #endif 416 .mmap = ecryptfs_mmap, 417 .open = ecryptfs_open, 418 .flush = ecryptfs_flush, 419 .release = ecryptfs_release, 420 .fsync = ecryptfs_fsync, 421 .fasync = ecryptfs_fasync, 422 .splice_read = generic_file_splice_read, 423 }; 424