Serge E. Hallyn | 08ce5f1 | 2008-04-29 01:00:10 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * dev_cgroup.c - device cgroup subsystem |
| 3 | * |
| 4 | * Copyright 2007 IBM Corp |
| 5 | */ |
| 6 | |
| 7 | #include <linux/device_cgroup.h> |
| 8 | #include <linux/cgroup.h> |
| 9 | #include <linux/ctype.h> |
| 10 | #include <linux/list.h> |
| 11 | #include <linux/uaccess.h> |
| 12 | |
| 13 | #define ACC_MKNOD 1 |
| 14 | #define ACC_READ 2 |
| 15 | #define ACC_WRITE 4 |
| 16 | #define ACC_MASK (ACC_MKNOD | ACC_READ | ACC_WRITE) |
| 17 | |
| 18 | #define DEV_BLOCK 1 |
| 19 | #define DEV_CHAR 2 |
| 20 | #define DEV_ALL 4 /* this represents all devices */ |
| 21 | |
| 22 | /* |
| 23 | * whitelist locking rules: |
| 24 | * cgroup_lock() cannot be taken under dev_cgroup->lock. |
| 25 | * dev_cgroup->lock can be taken with or without cgroup_lock(). |
| 26 | * |
| 27 | * modifications always require cgroup_lock |
| 28 | * modifications to a list which is visible require the |
| 29 | * dev_cgroup->lock *and* cgroup_lock() |
| 30 | * walking the list requires dev_cgroup->lock or cgroup_lock(). |
| 31 | * |
| 32 | * reasoning: dev_whitelist_copy() needs to kmalloc, so needs |
| 33 | * a mutex, which the cgroup_lock() is. Since modifying |
| 34 | * a visible list requires both locks, either lock can be |
| 35 | * taken for walking the list. |
| 36 | */ |
| 37 | |
| 38 | struct dev_whitelist_item { |
| 39 | u32 major, minor; |
| 40 | short type; |
| 41 | short access; |
| 42 | struct list_head list; |
| 43 | }; |
| 44 | |
| 45 | struct dev_cgroup { |
| 46 | struct cgroup_subsys_state css; |
| 47 | struct list_head whitelist; |
| 48 | spinlock_t lock; |
| 49 | }; |
| 50 | |
| 51 | static inline struct dev_cgroup *cgroup_to_devcgroup(struct cgroup *cgroup) |
| 52 | { |
| 53 | return container_of(cgroup_subsys_state(cgroup, devices_subsys_id), |
| 54 | struct dev_cgroup, css); |
| 55 | } |
| 56 | |
| 57 | struct cgroup_subsys devices_subsys; |
| 58 | |
| 59 | static int devcgroup_can_attach(struct cgroup_subsys *ss, |
| 60 | struct cgroup *new_cgroup, struct task_struct *task) |
| 61 | { |
| 62 | if (current != task && !capable(CAP_SYS_ADMIN)) |
| 63 | return -EPERM; |
| 64 | |
| 65 | return 0; |
| 66 | } |
| 67 | |
| 68 | /* |
| 69 | * called under cgroup_lock() |
| 70 | */ |
| 71 | static int dev_whitelist_copy(struct list_head *dest, struct list_head *orig) |
| 72 | { |
| 73 | struct dev_whitelist_item *wh, *tmp, *new; |
| 74 | |
| 75 | list_for_each_entry(wh, orig, list) { |
| 76 | new = kmalloc(sizeof(*wh), GFP_KERNEL); |
| 77 | if (!new) |
| 78 | goto free_and_exit; |
| 79 | new->major = wh->major; |
| 80 | new->minor = wh->minor; |
| 81 | new->type = wh->type; |
| 82 | new->access = wh->access; |
| 83 | list_add_tail(&new->list, dest); |
| 84 | } |
| 85 | |
| 86 | return 0; |
| 87 | |
| 88 | free_and_exit: |
| 89 | list_for_each_entry_safe(wh, tmp, dest, list) { |
| 90 | list_del(&wh->list); |
| 91 | kfree(wh); |
| 92 | } |
| 93 | return -ENOMEM; |
| 94 | } |
| 95 | |
| 96 | /* Stupid prototype - don't bother combining existing entries */ |
| 97 | /* |
| 98 | * called under cgroup_lock() |
| 99 | * since the list is visible to other tasks, we need the spinlock also |
| 100 | */ |
| 101 | static int dev_whitelist_add(struct dev_cgroup *dev_cgroup, |
| 102 | struct dev_whitelist_item *wh) |
| 103 | { |
| 104 | struct dev_whitelist_item *whcopy; |
| 105 | |
| 106 | whcopy = kmalloc(sizeof(*whcopy), GFP_KERNEL); |
| 107 | if (!whcopy) |
| 108 | return -ENOMEM; |
| 109 | |
| 110 | memcpy(whcopy, wh, sizeof(*whcopy)); |
| 111 | spin_lock(&dev_cgroup->lock); |
| 112 | list_add_tail(&whcopy->list, &dev_cgroup->whitelist); |
| 113 | spin_unlock(&dev_cgroup->lock); |
| 114 | return 0; |
| 115 | } |
| 116 | |
| 117 | /* |
| 118 | * called under cgroup_lock() |
| 119 | * since the list is visible to other tasks, we need the spinlock also |
| 120 | */ |
| 121 | static void dev_whitelist_rm(struct dev_cgroup *dev_cgroup, |
| 122 | struct dev_whitelist_item *wh) |
| 123 | { |
| 124 | struct dev_whitelist_item *walk, *tmp; |
| 125 | |
| 126 | spin_lock(&dev_cgroup->lock); |
| 127 | list_for_each_entry_safe(walk, tmp, &dev_cgroup->whitelist, list) { |
| 128 | if (walk->type == DEV_ALL) |
| 129 | goto remove; |
| 130 | if (walk->type != wh->type) |
| 131 | continue; |
| 132 | if (walk->major != ~0 && walk->major != wh->major) |
| 133 | continue; |
| 134 | if (walk->minor != ~0 && walk->minor != wh->minor) |
| 135 | continue; |
| 136 | |
| 137 | remove: |
| 138 | walk->access &= ~wh->access; |
| 139 | if (!walk->access) { |
| 140 | list_del(&walk->list); |
| 141 | kfree(walk); |
| 142 | } |
| 143 | } |
| 144 | spin_unlock(&dev_cgroup->lock); |
| 145 | } |
| 146 | |
| 147 | /* |
| 148 | * called from kernel/cgroup.c with cgroup_lock() held. |
| 149 | */ |
| 150 | static struct cgroup_subsys_state *devcgroup_create(struct cgroup_subsys *ss, |
| 151 | struct cgroup *cgroup) |
| 152 | { |
| 153 | struct dev_cgroup *dev_cgroup, *parent_dev_cgroup; |
| 154 | struct cgroup *parent_cgroup; |
| 155 | int ret; |
| 156 | |
| 157 | dev_cgroup = kzalloc(sizeof(*dev_cgroup), GFP_KERNEL); |
| 158 | if (!dev_cgroup) |
| 159 | return ERR_PTR(-ENOMEM); |
| 160 | INIT_LIST_HEAD(&dev_cgroup->whitelist); |
| 161 | parent_cgroup = cgroup->parent; |
| 162 | |
| 163 | if (parent_cgroup == NULL) { |
| 164 | struct dev_whitelist_item *wh; |
| 165 | wh = kmalloc(sizeof(*wh), GFP_KERNEL); |
| 166 | if (!wh) { |
| 167 | kfree(dev_cgroup); |
| 168 | return ERR_PTR(-ENOMEM); |
| 169 | } |
| 170 | wh->minor = wh->major = ~0; |
| 171 | wh->type = DEV_ALL; |
| 172 | wh->access = ACC_MKNOD | ACC_READ | ACC_WRITE; |
| 173 | list_add(&wh->list, &dev_cgroup->whitelist); |
| 174 | } else { |
| 175 | parent_dev_cgroup = cgroup_to_devcgroup(parent_cgroup); |
| 176 | ret = dev_whitelist_copy(&dev_cgroup->whitelist, |
| 177 | &parent_dev_cgroup->whitelist); |
| 178 | if (ret) { |
| 179 | kfree(dev_cgroup); |
| 180 | return ERR_PTR(ret); |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | spin_lock_init(&dev_cgroup->lock); |
| 185 | return &dev_cgroup->css; |
| 186 | } |
| 187 | |
| 188 | static void devcgroup_destroy(struct cgroup_subsys *ss, |
| 189 | struct cgroup *cgroup) |
| 190 | { |
| 191 | struct dev_cgroup *dev_cgroup; |
| 192 | struct dev_whitelist_item *wh, *tmp; |
| 193 | |
| 194 | dev_cgroup = cgroup_to_devcgroup(cgroup); |
| 195 | list_for_each_entry_safe(wh, tmp, &dev_cgroup->whitelist, list) { |
| 196 | list_del(&wh->list); |
| 197 | kfree(wh); |
| 198 | } |
| 199 | kfree(dev_cgroup); |
| 200 | } |
| 201 | |
| 202 | #define DEVCG_ALLOW 1 |
| 203 | #define DEVCG_DENY 2 |
| 204 | |
| 205 | static void set_access(char *acc, short access) |
| 206 | { |
| 207 | int idx = 0; |
| 208 | memset(acc, 0, 4); |
| 209 | if (access & ACC_READ) |
| 210 | acc[idx++] = 'r'; |
| 211 | if (access & ACC_WRITE) |
| 212 | acc[idx++] = 'w'; |
| 213 | if (access & ACC_MKNOD) |
| 214 | acc[idx++] = 'm'; |
| 215 | } |
| 216 | |
| 217 | static char type_to_char(short type) |
| 218 | { |
| 219 | if (type == DEV_ALL) |
| 220 | return 'a'; |
| 221 | if (type == DEV_CHAR) |
| 222 | return 'c'; |
| 223 | if (type == DEV_BLOCK) |
| 224 | return 'b'; |
| 225 | return 'X'; |
| 226 | } |
| 227 | |
| 228 | static void set_majmin(char *str, int len, unsigned m) |
| 229 | { |
| 230 | memset(str, 0, len); |
| 231 | if (m == ~0) |
| 232 | sprintf(str, "*"); |
| 233 | else |
| 234 | snprintf(str, len, "%d", m); |
| 235 | } |
| 236 | |
| 237 | static char *print_whitelist(struct dev_cgroup *devcgroup, int *len) |
| 238 | { |
| 239 | char *buf, *s, acc[4]; |
| 240 | struct dev_whitelist_item *wh; |
| 241 | int ret; |
| 242 | int count = 0; |
| 243 | char maj[10], min[10]; |
| 244 | |
| 245 | buf = kmalloc(4096, GFP_KERNEL); |
| 246 | if (!buf) |
| 247 | return ERR_PTR(-ENOMEM); |
| 248 | s = buf; |
| 249 | *s = '\0'; |
| 250 | *len = 0; |
| 251 | |
| 252 | spin_lock(&devcgroup->lock); |
| 253 | list_for_each_entry(wh, &devcgroup->whitelist, list) { |
| 254 | set_access(acc, wh->access); |
| 255 | set_majmin(maj, 10, wh->major); |
| 256 | set_majmin(min, 10, wh->minor); |
| 257 | ret = snprintf(s, 4095-(s-buf), "%c %s:%s %s\n", |
| 258 | type_to_char(wh->type), maj, min, acc); |
| 259 | if (s+ret >= buf+4095) { |
| 260 | kfree(buf); |
| 261 | buf = ERR_PTR(-ENOMEM); |
| 262 | break; |
| 263 | } |
| 264 | s += ret; |
| 265 | *len += ret; |
| 266 | count++; |
| 267 | } |
| 268 | spin_unlock(&devcgroup->lock); |
| 269 | |
| 270 | return buf; |
| 271 | } |
| 272 | |
| 273 | static ssize_t devcgroup_access_read(struct cgroup *cgroup, |
| 274 | struct cftype *cft, struct file *file, |
| 275 | char __user *userbuf, size_t nbytes, loff_t *ppos) |
| 276 | { |
| 277 | struct dev_cgroup *devcgroup = cgroup_to_devcgroup(cgroup); |
| 278 | int filetype = cft->private; |
| 279 | char *buffer; |
| 280 | int uninitialized_var(len); |
| 281 | int retval; |
| 282 | |
| 283 | if (filetype != DEVCG_ALLOW) |
| 284 | return -EINVAL; |
| 285 | buffer = print_whitelist(devcgroup, &len); |
| 286 | if (IS_ERR(buffer)) |
| 287 | return PTR_ERR(buffer); |
| 288 | |
| 289 | retval = simple_read_from_buffer(userbuf, nbytes, ppos, buffer, len); |
| 290 | kfree(buffer); |
| 291 | return retval; |
| 292 | } |
| 293 | |
| 294 | /* |
| 295 | * may_access_whitelist: |
| 296 | * does the access granted to dev_cgroup c contain the access |
| 297 | * requested in whitelist item refwh. |
| 298 | * return 1 if yes, 0 if no. |
| 299 | * call with c->lock held |
| 300 | */ |
| 301 | static int may_access_whitelist(struct dev_cgroup *c, |
| 302 | struct dev_whitelist_item *refwh) |
| 303 | { |
| 304 | struct dev_whitelist_item *whitem; |
| 305 | |
| 306 | list_for_each_entry(whitem, &c->whitelist, list) { |
| 307 | if (whitem->type & DEV_ALL) |
| 308 | return 1; |
| 309 | if ((refwh->type & DEV_BLOCK) && !(whitem->type & DEV_BLOCK)) |
| 310 | continue; |
| 311 | if ((refwh->type & DEV_CHAR) && !(whitem->type & DEV_CHAR)) |
| 312 | continue; |
| 313 | if (whitem->major != ~0 && whitem->major != refwh->major) |
| 314 | continue; |
| 315 | if (whitem->minor != ~0 && whitem->minor != refwh->minor) |
| 316 | continue; |
| 317 | if (refwh->access & (~(whitem->access | ACC_MASK))) |
| 318 | continue; |
| 319 | return 1; |
| 320 | } |
| 321 | return 0; |
| 322 | } |
| 323 | |
| 324 | /* |
| 325 | * parent_has_perm: |
| 326 | * when adding a new allow rule to a device whitelist, the rule |
| 327 | * must be allowed in the parent device |
| 328 | */ |
| 329 | static int parent_has_perm(struct cgroup *childcg, |
| 330 | struct dev_whitelist_item *wh) |
| 331 | { |
| 332 | struct cgroup *pcg = childcg->parent; |
| 333 | struct dev_cgroup *parent; |
| 334 | int ret; |
| 335 | |
| 336 | if (!pcg) |
| 337 | return 1; |
| 338 | parent = cgroup_to_devcgroup(pcg); |
| 339 | spin_lock(&parent->lock); |
| 340 | ret = may_access_whitelist(parent, wh); |
| 341 | spin_unlock(&parent->lock); |
| 342 | return ret; |
| 343 | } |
| 344 | |
| 345 | /* |
| 346 | * Modify the whitelist using allow/deny rules. |
| 347 | * CAP_SYS_ADMIN is needed for this. It's at least separate from CAP_MKNOD |
| 348 | * so we can give a container CAP_MKNOD to let it create devices but not |
| 349 | * modify the whitelist. |
| 350 | * It seems likely we'll want to add a CAP_CONTAINER capability to allow |
| 351 | * us to also grant CAP_SYS_ADMIN to containers without giving away the |
| 352 | * device whitelist controls, but for now we'll stick with CAP_SYS_ADMIN |
| 353 | * |
| 354 | * Taking rules away is always allowed (given CAP_SYS_ADMIN). Granting |
| 355 | * new access is only allowed if you're in the top-level cgroup, or your |
| 356 | * parent cgroup has the access you're asking for. |
| 357 | */ |
| 358 | static ssize_t devcgroup_access_write(struct cgroup *cgroup, struct cftype *cft, |
| 359 | struct file *file, const char __user *userbuf, |
| 360 | size_t nbytes, loff_t *ppos) |
| 361 | { |
| 362 | struct cgroup *cur_cgroup; |
| 363 | struct dev_cgroup *devcgroup, *cur_devcgroup; |
| 364 | int filetype = cft->private; |
| 365 | char *buffer, *b; |
| 366 | int retval = 0, count; |
| 367 | struct dev_whitelist_item wh; |
| 368 | |
| 369 | if (!capable(CAP_SYS_ADMIN)) |
| 370 | return -EPERM; |
| 371 | |
| 372 | devcgroup = cgroup_to_devcgroup(cgroup); |
| 373 | cur_cgroup = task_cgroup(current, devices_subsys.subsys_id); |
| 374 | cur_devcgroup = cgroup_to_devcgroup(cur_cgroup); |
| 375 | |
| 376 | buffer = kmalloc(nbytes+1, GFP_KERNEL); |
| 377 | if (!buffer) |
| 378 | return -ENOMEM; |
| 379 | |
| 380 | if (copy_from_user(buffer, userbuf, nbytes)) { |
| 381 | retval = -EFAULT; |
| 382 | goto out1; |
| 383 | } |
| 384 | buffer[nbytes] = 0; /* nul-terminate */ |
| 385 | |
| 386 | cgroup_lock(); |
| 387 | if (cgroup_is_removed(cgroup)) { |
| 388 | retval = -ENODEV; |
| 389 | goto out2; |
| 390 | } |
| 391 | |
| 392 | memset(&wh, 0, sizeof(wh)); |
| 393 | b = buffer; |
| 394 | |
| 395 | switch (*b) { |
| 396 | case 'a': |
| 397 | wh.type = DEV_ALL; |
| 398 | wh.access = ACC_MASK; |
| 399 | goto handle; |
| 400 | case 'b': |
| 401 | wh.type = DEV_BLOCK; |
| 402 | break; |
| 403 | case 'c': |
| 404 | wh.type = DEV_CHAR; |
| 405 | break; |
| 406 | default: |
| 407 | retval = -EINVAL; |
| 408 | goto out2; |
| 409 | } |
| 410 | b++; |
| 411 | if (!isspace(*b)) { |
| 412 | retval = -EINVAL; |
| 413 | goto out2; |
| 414 | } |
| 415 | b++; |
| 416 | if (*b == '*') { |
| 417 | wh.major = ~0; |
| 418 | b++; |
| 419 | } else if (isdigit(*b)) { |
| 420 | wh.major = 0; |
| 421 | while (isdigit(*b)) { |
| 422 | wh.major = wh.major*10+(*b-'0'); |
| 423 | b++; |
| 424 | } |
| 425 | } else { |
| 426 | retval = -EINVAL; |
| 427 | goto out2; |
| 428 | } |
| 429 | if (*b != ':') { |
| 430 | retval = -EINVAL; |
| 431 | goto out2; |
| 432 | } |
| 433 | b++; |
| 434 | |
| 435 | /* read minor */ |
| 436 | if (*b == '*') { |
| 437 | wh.minor = ~0; |
| 438 | b++; |
| 439 | } else if (isdigit(*b)) { |
| 440 | wh.minor = 0; |
| 441 | while (isdigit(*b)) { |
| 442 | wh.minor = wh.minor*10+(*b-'0'); |
| 443 | b++; |
| 444 | } |
| 445 | } else { |
| 446 | retval = -EINVAL; |
| 447 | goto out2; |
| 448 | } |
| 449 | if (!isspace(*b)) { |
| 450 | retval = -EINVAL; |
| 451 | goto out2; |
| 452 | } |
| 453 | for (b++, count = 0; count < 3; count++, b++) { |
| 454 | switch (*b) { |
| 455 | case 'r': |
| 456 | wh.access |= ACC_READ; |
| 457 | break; |
| 458 | case 'w': |
| 459 | wh.access |= ACC_WRITE; |
| 460 | break; |
| 461 | case 'm': |
| 462 | wh.access |= ACC_MKNOD; |
| 463 | break; |
| 464 | case '\n': |
| 465 | case '\0': |
| 466 | count = 3; |
| 467 | break; |
| 468 | default: |
| 469 | retval = -EINVAL; |
| 470 | goto out2; |
| 471 | } |
| 472 | } |
| 473 | |
| 474 | handle: |
| 475 | retval = 0; |
| 476 | switch (filetype) { |
| 477 | case DEVCG_ALLOW: |
| 478 | if (!parent_has_perm(cgroup, &wh)) |
| 479 | retval = -EPERM; |
| 480 | else |
| 481 | retval = dev_whitelist_add(devcgroup, &wh); |
| 482 | break; |
| 483 | case DEVCG_DENY: |
| 484 | dev_whitelist_rm(devcgroup, &wh); |
| 485 | break; |
| 486 | default: |
| 487 | retval = -EINVAL; |
| 488 | goto out2; |
| 489 | } |
| 490 | |
| 491 | if (retval == 0) |
| 492 | retval = nbytes; |
| 493 | |
| 494 | out2: |
| 495 | cgroup_unlock(); |
| 496 | out1: |
| 497 | kfree(buffer); |
| 498 | return retval; |
| 499 | } |
| 500 | |
| 501 | static struct cftype dev_cgroup_files[] = { |
| 502 | { |
| 503 | .name = "allow", |
| 504 | .read = devcgroup_access_read, |
| 505 | .write = devcgroup_access_write, |
| 506 | .private = DEVCG_ALLOW, |
| 507 | }, |
| 508 | { |
| 509 | .name = "deny", |
| 510 | .write = devcgroup_access_write, |
| 511 | .private = DEVCG_DENY, |
| 512 | }, |
| 513 | }; |
| 514 | |
| 515 | static int devcgroup_populate(struct cgroup_subsys *ss, |
| 516 | struct cgroup *cgroup) |
| 517 | { |
| 518 | return cgroup_add_files(cgroup, ss, dev_cgroup_files, |
| 519 | ARRAY_SIZE(dev_cgroup_files)); |
| 520 | } |
| 521 | |
| 522 | struct cgroup_subsys devices_subsys = { |
| 523 | .name = "devices", |
| 524 | .can_attach = devcgroup_can_attach, |
| 525 | .create = devcgroup_create, |
| 526 | .destroy = devcgroup_destroy, |
| 527 | .populate = devcgroup_populate, |
| 528 | .subsys_id = devices_subsys_id, |
| 529 | }; |
| 530 | |
| 531 | int devcgroup_inode_permission(struct inode *inode, int mask) |
| 532 | { |
| 533 | struct cgroup *cgroup; |
| 534 | struct dev_cgroup *dev_cgroup; |
| 535 | struct dev_whitelist_item *wh; |
| 536 | |
| 537 | dev_t device = inode->i_rdev; |
| 538 | if (!device) |
| 539 | return 0; |
| 540 | if (!S_ISBLK(inode->i_mode) && !S_ISCHR(inode->i_mode)) |
| 541 | return 0; |
| 542 | cgroup = task_cgroup(current, devices_subsys.subsys_id); |
| 543 | dev_cgroup = cgroup_to_devcgroup(cgroup); |
| 544 | if (!dev_cgroup) |
| 545 | return 0; |
| 546 | |
| 547 | spin_lock(&dev_cgroup->lock); |
| 548 | list_for_each_entry(wh, &dev_cgroup->whitelist, list) { |
| 549 | if (wh->type & DEV_ALL) |
| 550 | goto acc_check; |
| 551 | if ((wh->type & DEV_BLOCK) && !S_ISBLK(inode->i_mode)) |
| 552 | continue; |
| 553 | if ((wh->type & DEV_CHAR) && !S_ISCHR(inode->i_mode)) |
| 554 | continue; |
| 555 | if (wh->major != ~0 && wh->major != imajor(inode)) |
| 556 | continue; |
| 557 | if (wh->minor != ~0 && wh->minor != iminor(inode)) |
| 558 | continue; |
| 559 | acc_check: |
| 560 | if ((mask & MAY_WRITE) && !(wh->access & ACC_WRITE)) |
| 561 | continue; |
| 562 | if ((mask & MAY_READ) && !(wh->access & ACC_READ)) |
| 563 | continue; |
| 564 | spin_unlock(&dev_cgroup->lock); |
| 565 | return 0; |
| 566 | } |
| 567 | spin_unlock(&dev_cgroup->lock); |
| 568 | |
| 569 | return -EPERM; |
| 570 | } |
| 571 | |
| 572 | int devcgroup_inode_mknod(int mode, dev_t dev) |
| 573 | { |
| 574 | struct cgroup *cgroup; |
| 575 | struct dev_cgroup *dev_cgroup; |
| 576 | struct dev_whitelist_item *wh; |
| 577 | |
| 578 | cgroup = task_cgroup(current, devices_subsys.subsys_id); |
| 579 | dev_cgroup = cgroup_to_devcgroup(cgroup); |
| 580 | if (!dev_cgroup) |
| 581 | return 0; |
| 582 | |
| 583 | spin_lock(&dev_cgroup->lock); |
| 584 | list_for_each_entry(wh, &dev_cgroup->whitelist, list) { |
| 585 | if (wh->type & DEV_ALL) |
| 586 | goto acc_check; |
| 587 | if ((wh->type & DEV_BLOCK) && !S_ISBLK(mode)) |
| 588 | continue; |
| 589 | if ((wh->type & DEV_CHAR) && !S_ISCHR(mode)) |
| 590 | continue; |
| 591 | if (wh->major != ~0 && wh->major != MAJOR(dev)) |
| 592 | continue; |
| 593 | if (wh->minor != ~0 && wh->minor != MINOR(dev)) |
| 594 | continue; |
| 595 | acc_check: |
| 596 | if (!(wh->access & ACC_MKNOD)) |
| 597 | continue; |
| 598 | spin_unlock(&dev_cgroup->lock); |
| 599 | return 0; |
| 600 | } |
| 601 | spin_unlock(&dev_cgroup->lock); |
| 602 | return -EPERM; |
| 603 | } |