| 1 | /* |
| 2 | File: fs/xattr.c |
| 3 | |
| 4 | Extended attribute handling. |
| 5 | |
| 6 | Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org> |
| 7 | Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com> |
| 8 | Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> |
| 9 | */ |
| 10 | #include <linux/fs.h> |
| 11 | #include <linux/slab.h> |
| 12 | #include <linux/smp_lock.h> |
| 13 | #include <linux/file.h> |
| 14 | #include <linux/xattr.h> |
| 15 | #include <linux/namei.h> |
| 16 | #include <linux/security.h> |
| 17 | #include <linux/syscalls.h> |
| 18 | #include <linux/module.h> |
| 19 | #include <linux/fsnotify.h> |
| 20 | #include <asm/uaccess.h> |
| 21 | |
| 22 | |
| 23 | int |
| 24 | vfs_setxattr(struct dentry *dentry, char *name, void *value, |
| 25 | size_t size, int flags) |
| 26 | { |
| 27 | struct inode *inode = dentry->d_inode; |
| 28 | int error; |
| 29 | |
| 30 | mutex_lock(&inode->i_mutex); |
| 31 | error = security_inode_setxattr(dentry, name, value, size, flags); |
| 32 | if (error) |
| 33 | goto out; |
| 34 | error = -EOPNOTSUPP; |
| 35 | if (inode->i_op->setxattr) { |
| 36 | error = inode->i_op->setxattr(dentry, name, value, size, flags); |
| 37 | if (!error) { |
| 38 | fsnotify_xattr(dentry); |
| 39 | security_inode_post_setxattr(dentry, name, value, |
| 40 | size, flags); |
| 41 | } |
| 42 | } else if (!strncmp(name, XATTR_SECURITY_PREFIX, |
| 43 | sizeof XATTR_SECURITY_PREFIX - 1)) { |
| 44 | const char *suffix = name + sizeof XATTR_SECURITY_PREFIX - 1; |
| 45 | error = security_inode_setsecurity(inode, suffix, value, |
| 46 | size, flags); |
| 47 | if (!error) |
| 48 | fsnotify_xattr(dentry); |
| 49 | } |
| 50 | out: |
| 51 | mutex_unlock(&inode->i_mutex); |
| 52 | return error; |
| 53 | } |
| 54 | EXPORT_SYMBOL_GPL(vfs_setxattr); |
| 55 | |
| 56 | ssize_t |
| 57 | vfs_getxattr(struct dentry *dentry, char *name, void *value, size_t size) |
| 58 | { |
| 59 | struct inode *inode = dentry->d_inode; |
| 60 | int error; |
| 61 | |
| 62 | error = security_inode_getxattr(dentry, name); |
| 63 | if (error) |
| 64 | return error; |
| 65 | |
| 66 | if (inode->i_op->getxattr) |
| 67 | error = inode->i_op->getxattr(dentry, name, value, size); |
| 68 | else |
| 69 | error = -EOPNOTSUPP; |
| 70 | |
| 71 | if (!strncmp(name, XATTR_SECURITY_PREFIX, |
| 72 | sizeof XATTR_SECURITY_PREFIX - 1)) { |
| 73 | const char *suffix = name + sizeof XATTR_SECURITY_PREFIX - 1; |
| 74 | int ret = security_inode_getsecurity(inode, suffix, value, |
| 75 | size, error); |
| 76 | /* |
| 77 | * Only overwrite the return value if a security module |
| 78 | * is actually active. |
| 79 | */ |
| 80 | if (ret != -EOPNOTSUPP) |
| 81 | error = ret; |
| 82 | } |
| 83 | |
| 84 | return error; |
| 85 | } |
| 86 | EXPORT_SYMBOL_GPL(vfs_getxattr); |
| 87 | |
| 88 | int |
| 89 | vfs_removexattr(struct dentry *dentry, char *name) |
| 90 | { |
| 91 | struct inode *inode = dentry->d_inode; |
| 92 | int error; |
| 93 | |
| 94 | if (!inode->i_op->removexattr) |
| 95 | return -EOPNOTSUPP; |
| 96 | |
| 97 | error = security_inode_removexattr(dentry, name); |
| 98 | if (error) |
| 99 | return error; |
| 100 | |
| 101 | mutex_lock(&inode->i_mutex); |
| 102 | error = inode->i_op->removexattr(dentry, name); |
| 103 | mutex_unlock(&inode->i_mutex); |
| 104 | |
| 105 | if (!error) |
| 106 | fsnotify_xattr(dentry); |
| 107 | return error; |
| 108 | } |
| 109 | EXPORT_SYMBOL_GPL(vfs_removexattr); |
| 110 | |
| 111 | |
| 112 | /* |
| 113 | * Extended attribute SET operations |
| 114 | */ |
| 115 | static long |
| 116 | setxattr(struct dentry *d, char __user *name, void __user *value, |
| 117 | size_t size, int flags) |
| 118 | { |
| 119 | int error; |
| 120 | void *kvalue = NULL; |
| 121 | char kname[XATTR_NAME_MAX + 1]; |
| 122 | |
| 123 | if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) |
| 124 | return -EINVAL; |
| 125 | |
| 126 | error = strncpy_from_user(kname, name, sizeof(kname)); |
| 127 | if (error == 0 || error == sizeof(kname)) |
| 128 | error = -ERANGE; |
| 129 | if (error < 0) |
| 130 | return error; |
| 131 | |
| 132 | if (size) { |
| 133 | if (size > XATTR_SIZE_MAX) |
| 134 | return -E2BIG; |
| 135 | kvalue = kmalloc(size, GFP_KERNEL); |
| 136 | if (!kvalue) |
| 137 | return -ENOMEM; |
| 138 | if (copy_from_user(kvalue, value, size)) { |
| 139 | kfree(kvalue); |
| 140 | return -EFAULT; |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | error = vfs_setxattr(d, kname, kvalue, size, flags); |
| 145 | kfree(kvalue); |
| 146 | return error; |
| 147 | } |
| 148 | |
| 149 | asmlinkage long |
| 150 | sys_setxattr(char __user *path, char __user *name, void __user *value, |
| 151 | size_t size, int flags) |
| 152 | { |
| 153 | struct nameidata nd; |
| 154 | int error; |
| 155 | |
| 156 | error = user_path_walk(path, &nd); |
| 157 | if (error) |
| 158 | return error; |
| 159 | error = setxattr(nd.dentry, name, value, size, flags); |
| 160 | path_release(&nd); |
| 161 | return error; |
| 162 | } |
| 163 | |
| 164 | asmlinkage long |
| 165 | sys_lsetxattr(char __user *path, char __user *name, void __user *value, |
| 166 | size_t size, int flags) |
| 167 | { |
| 168 | struct nameidata nd; |
| 169 | int error; |
| 170 | |
| 171 | error = user_path_walk_link(path, &nd); |
| 172 | if (error) |
| 173 | return error; |
| 174 | error = setxattr(nd.dentry, name, value, size, flags); |
| 175 | path_release(&nd); |
| 176 | return error; |
| 177 | } |
| 178 | |
| 179 | asmlinkage long |
| 180 | sys_fsetxattr(int fd, char __user *name, void __user *value, |
| 181 | size_t size, int flags) |
| 182 | { |
| 183 | struct file *f; |
| 184 | int error = -EBADF; |
| 185 | |
| 186 | f = fget(fd); |
| 187 | if (!f) |
| 188 | return error; |
| 189 | error = setxattr(f->f_dentry, name, value, size, flags); |
| 190 | fput(f); |
| 191 | return error; |
| 192 | } |
| 193 | |
| 194 | /* |
| 195 | * Extended attribute GET operations |
| 196 | */ |
| 197 | static ssize_t |
| 198 | getxattr(struct dentry *d, char __user *name, void __user *value, size_t size) |
| 199 | { |
| 200 | ssize_t error; |
| 201 | void *kvalue = NULL; |
| 202 | char kname[XATTR_NAME_MAX + 1]; |
| 203 | |
| 204 | error = strncpy_from_user(kname, name, sizeof(kname)); |
| 205 | if (error == 0 || error == sizeof(kname)) |
| 206 | error = -ERANGE; |
| 207 | if (error < 0) |
| 208 | return error; |
| 209 | |
| 210 | if (size) { |
| 211 | if (size > XATTR_SIZE_MAX) |
| 212 | size = XATTR_SIZE_MAX; |
| 213 | kvalue = kzalloc(size, GFP_KERNEL); |
| 214 | if (!kvalue) |
| 215 | return -ENOMEM; |
| 216 | } |
| 217 | |
| 218 | error = vfs_getxattr(d, kname, kvalue, size); |
| 219 | if (error > 0) { |
| 220 | if (size && copy_to_user(value, kvalue, error)) |
| 221 | error = -EFAULT; |
| 222 | } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { |
| 223 | /* The file system tried to returned a value bigger |
| 224 | than XATTR_SIZE_MAX bytes. Not possible. */ |
| 225 | error = -E2BIG; |
| 226 | } |
| 227 | kfree(kvalue); |
| 228 | return error; |
| 229 | } |
| 230 | |
| 231 | asmlinkage ssize_t |
| 232 | sys_getxattr(char __user *path, char __user *name, void __user *value, |
| 233 | size_t size) |
| 234 | { |
| 235 | struct nameidata nd; |
| 236 | ssize_t error; |
| 237 | |
| 238 | error = user_path_walk(path, &nd); |
| 239 | if (error) |
| 240 | return error; |
| 241 | error = getxattr(nd.dentry, name, value, size); |
| 242 | path_release(&nd); |
| 243 | return error; |
| 244 | } |
| 245 | |
| 246 | asmlinkage ssize_t |
| 247 | sys_lgetxattr(char __user *path, char __user *name, void __user *value, |
| 248 | size_t size) |
| 249 | { |
| 250 | struct nameidata nd; |
| 251 | ssize_t error; |
| 252 | |
| 253 | error = user_path_walk_link(path, &nd); |
| 254 | if (error) |
| 255 | return error; |
| 256 | error = getxattr(nd.dentry, name, value, size); |
| 257 | path_release(&nd); |
| 258 | return error; |
| 259 | } |
| 260 | |
| 261 | asmlinkage ssize_t |
| 262 | sys_fgetxattr(int fd, char __user *name, void __user *value, size_t size) |
| 263 | { |
| 264 | struct file *f; |
| 265 | ssize_t error = -EBADF; |
| 266 | |
| 267 | f = fget(fd); |
| 268 | if (!f) |
| 269 | return error; |
| 270 | error = getxattr(f->f_dentry, name, value, size); |
| 271 | fput(f); |
| 272 | return error; |
| 273 | } |
| 274 | |
| 275 | /* |
| 276 | * Extended attribute LIST operations |
| 277 | */ |
| 278 | static ssize_t |
| 279 | listxattr(struct dentry *d, char __user *list, size_t size) |
| 280 | { |
| 281 | ssize_t error; |
| 282 | char *klist = NULL; |
| 283 | |
| 284 | if (size) { |
| 285 | if (size > XATTR_LIST_MAX) |
| 286 | size = XATTR_LIST_MAX; |
| 287 | klist = kmalloc(size, GFP_KERNEL); |
| 288 | if (!klist) |
| 289 | return -ENOMEM; |
| 290 | } |
| 291 | |
| 292 | error = security_inode_listxattr(d); |
| 293 | if (error) |
| 294 | goto out; |
| 295 | error = -EOPNOTSUPP; |
| 296 | if (d->d_inode->i_op && d->d_inode->i_op->listxattr) { |
| 297 | error = d->d_inode->i_op->listxattr(d, klist, size); |
| 298 | } else { |
| 299 | error = security_inode_listsecurity(d->d_inode, klist, size); |
| 300 | if (size && error > size) |
| 301 | error = -ERANGE; |
| 302 | } |
| 303 | if (error > 0) { |
| 304 | if (size && copy_to_user(list, klist, error)) |
| 305 | error = -EFAULT; |
| 306 | } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { |
| 307 | /* The file system tried to returned a list bigger |
| 308 | than XATTR_LIST_MAX bytes. Not possible. */ |
| 309 | error = -E2BIG; |
| 310 | } |
| 311 | out: |
| 312 | kfree(klist); |
| 313 | return error; |
| 314 | } |
| 315 | |
| 316 | asmlinkage ssize_t |
| 317 | sys_listxattr(char __user *path, char __user *list, size_t size) |
| 318 | { |
| 319 | struct nameidata nd; |
| 320 | ssize_t error; |
| 321 | |
| 322 | error = user_path_walk(path, &nd); |
| 323 | if (error) |
| 324 | return error; |
| 325 | error = listxattr(nd.dentry, list, size); |
| 326 | path_release(&nd); |
| 327 | return error; |
| 328 | } |
| 329 | |
| 330 | asmlinkage ssize_t |
| 331 | sys_llistxattr(char __user *path, char __user *list, size_t size) |
| 332 | { |
| 333 | struct nameidata nd; |
| 334 | ssize_t error; |
| 335 | |
| 336 | error = user_path_walk_link(path, &nd); |
| 337 | if (error) |
| 338 | return error; |
| 339 | error = listxattr(nd.dentry, list, size); |
| 340 | path_release(&nd); |
| 341 | return error; |
| 342 | } |
| 343 | |
| 344 | asmlinkage ssize_t |
| 345 | sys_flistxattr(int fd, char __user *list, size_t size) |
| 346 | { |
| 347 | struct file *f; |
| 348 | ssize_t error = -EBADF; |
| 349 | |
| 350 | f = fget(fd); |
| 351 | if (!f) |
| 352 | return error; |
| 353 | error = listxattr(f->f_dentry, list, size); |
| 354 | fput(f); |
| 355 | return error; |
| 356 | } |
| 357 | |
| 358 | /* |
| 359 | * Extended attribute REMOVE operations |
| 360 | */ |
| 361 | static long |
| 362 | removexattr(struct dentry *d, char __user *name) |
| 363 | { |
| 364 | int error; |
| 365 | char kname[XATTR_NAME_MAX + 1]; |
| 366 | |
| 367 | error = strncpy_from_user(kname, name, sizeof(kname)); |
| 368 | if (error == 0 || error == sizeof(kname)) |
| 369 | error = -ERANGE; |
| 370 | if (error < 0) |
| 371 | return error; |
| 372 | |
| 373 | return vfs_removexattr(d, kname); |
| 374 | } |
| 375 | |
| 376 | asmlinkage long |
| 377 | sys_removexattr(char __user *path, char __user *name) |
| 378 | { |
| 379 | struct nameidata nd; |
| 380 | int error; |
| 381 | |
| 382 | error = user_path_walk(path, &nd); |
| 383 | if (error) |
| 384 | return error; |
| 385 | error = removexattr(nd.dentry, name); |
| 386 | path_release(&nd); |
| 387 | return error; |
| 388 | } |
| 389 | |
| 390 | asmlinkage long |
| 391 | sys_lremovexattr(char __user *path, char __user *name) |
| 392 | { |
| 393 | struct nameidata nd; |
| 394 | int error; |
| 395 | |
| 396 | error = user_path_walk_link(path, &nd); |
| 397 | if (error) |
| 398 | return error; |
| 399 | error = removexattr(nd.dentry, name); |
| 400 | path_release(&nd); |
| 401 | return error; |
| 402 | } |
| 403 | |
| 404 | asmlinkage long |
| 405 | sys_fremovexattr(int fd, char __user *name) |
| 406 | { |
| 407 | struct file *f; |
| 408 | int error = -EBADF; |
| 409 | |
| 410 | f = fget(fd); |
| 411 | if (!f) |
| 412 | return error; |
| 413 | error = removexattr(f->f_dentry, name); |
| 414 | fput(f); |
| 415 | return error; |
| 416 | } |
| 417 | |
| 418 | |
| 419 | static const char * |
| 420 | strcmp_prefix(const char *a, const char *a_prefix) |
| 421 | { |
| 422 | while (*a_prefix && *a == *a_prefix) { |
| 423 | a++; |
| 424 | a_prefix++; |
| 425 | } |
| 426 | return *a_prefix ? NULL : a; |
| 427 | } |
| 428 | |
| 429 | /* |
| 430 | * In order to implement different sets of xattr operations for each xattr |
| 431 | * prefix with the generic xattr API, a filesystem should create a |
| 432 | * null-terminated array of struct xattr_handler (one for each prefix) and |
| 433 | * hang a pointer to it off of the s_xattr field of the superblock. |
| 434 | * |
| 435 | * The generic_fooxattr() functions will use this list to dispatch xattr |
| 436 | * operations to the correct xattr_handler. |
| 437 | */ |
| 438 | #define for_each_xattr_handler(handlers, handler) \ |
| 439 | for ((handler) = *(handlers)++; \ |
| 440 | (handler) != NULL; \ |
| 441 | (handler) = *(handlers)++) |
| 442 | |
| 443 | /* |
| 444 | * Find the xattr_handler with the matching prefix. |
| 445 | */ |
| 446 | static struct xattr_handler * |
| 447 | xattr_resolve_name(struct xattr_handler **handlers, const char **name) |
| 448 | { |
| 449 | struct xattr_handler *handler; |
| 450 | |
| 451 | if (!*name) |
| 452 | return NULL; |
| 453 | |
| 454 | for_each_xattr_handler(handlers, handler) { |
| 455 | const char *n = strcmp_prefix(*name, handler->prefix); |
| 456 | if (n) { |
| 457 | *name = n; |
| 458 | break; |
| 459 | } |
| 460 | } |
| 461 | return handler; |
| 462 | } |
| 463 | |
| 464 | /* |
| 465 | * Find the handler for the prefix and dispatch its get() operation. |
| 466 | */ |
| 467 | ssize_t |
| 468 | generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) |
| 469 | { |
| 470 | struct xattr_handler *handler; |
| 471 | struct inode *inode = dentry->d_inode; |
| 472 | |
| 473 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); |
| 474 | if (!handler) |
| 475 | return -EOPNOTSUPP; |
| 476 | return handler->get(inode, name, buffer, size); |
| 477 | } |
| 478 | |
| 479 | /* |
| 480 | * Combine the results of the list() operation from every xattr_handler in the |
| 481 | * list. |
| 482 | */ |
| 483 | ssize_t |
| 484 | generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) |
| 485 | { |
| 486 | struct inode *inode = dentry->d_inode; |
| 487 | struct xattr_handler *handler, **handlers = inode->i_sb->s_xattr; |
| 488 | unsigned int size = 0; |
| 489 | |
| 490 | if (!buffer) { |
| 491 | for_each_xattr_handler(handlers, handler) |
| 492 | size += handler->list(inode, NULL, 0, NULL, 0); |
| 493 | } else { |
| 494 | char *buf = buffer; |
| 495 | |
| 496 | for_each_xattr_handler(handlers, handler) { |
| 497 | size = handler->list(inode, buf, buffer_size, NULL, 0); |
| 498 | if (size > buffer_size) |
| 499 | return -ERANGE; |
| 500 | buf += size; |
| 501 | buffer_size -= size; |
| 502 | } |
| 503 | size = buf - buffer; |
| 504 | } |
| 505 | return size; |
| 506 | } |
| 507 | |
| 508 | /* |
| 509 | * Find the handler for the prefix and dispatch its set() operation. |
| 510 | */ |
| 511 | int |
| 512 | generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) |
| 513 | { |
| 514 | struct xattr_handler *handler; |
| 515 | struct inode *inode = dentry->d_inode; |
| 516 | |
| 517 | if (size == 0) |
| 518 | value = ""; /* empty EA, do not remove */ |
| 519 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); |
| 520 | if (!handler) |
| 521 | return -EOPNOTSUPP; |
| 522 | return handler->set(inode, name, value, size, flags); |
| 523 | } |
| 524 | |
| 525 | /* |
| 526 | * Find the handler for the prefix and dispatch its set() operation to remove |
| 527 | * any associated extended attribute. |
| 528 | */ |
| 529 | int |
| 530 | generic_removexattr(struct dentry *dentry, const char *name) |
| 531 | { |
| 532 | struct xattr_handler *handler; |
| 533 | struct inode *inode = dentry->d_inode; |
| 534 | |
| 535 | handler = xattr_resolve_name(inode->i_sb->s_xattr, &name); |
| 536 | if (!handler) |
| 537 | return -EOPNOTSUPP; |
| 538 | return handler->set(inode, name, NULL, 0, XATTR_REPLACE); |
| 539 | } |
| 540 | |
| 541 | EXPORT_SYMBOL(generic_getxattr); |
| 542 | EXPORT_SYMBOL(generic_listxattr); |
| 543 | EXPORT_SYMBOL(generic_setxattr); |
| 544 | EXPORT_SYMBOL(generic_removexattr); |