1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Minimal file system backend for holding eBPF maps and programs, 4 * used by bpf(2) object pinning. 5 * 6 * Authors: 7 * 8 * Daniel Borkmann <daniel@iogearbox.net> 9 */ 10 11 #include <linux/init.h> 12 #include <linux/magic.h> 13 #include <linux/major.h> 14 #include <linux/mount.h> 15 #include <linux/namei.h> 16 #include <linux/fs.h> 17 #include <linux/fs_context.h> 18 #include <linux/fs_parser.h> 19 #include <linux/kdev_t.h> 20 #include <linux/filter.h> 21 #include <linux/bpf.h> 22 #include <linux/bpf_trace.h> 23 #include "preload/bpf_preload.h" 24 25 enum bpf_type { 26 BPF_TYPE_UNSPEC = 0, 27 BPF_TYPE_PROG, 28 BPF_TYPE_MAP, 29 BPF_TYPE_LINK, 30 }; 31 32 static void *bpf_any_get(void *raw, enum bpf_type type) 33 { 34 switch (type) { 35 case BPF_TYPE_PROG: 36 bpf_prog_inc(raw); 37 break; 38 case BPF_TYPE_MAP: 39 bpf_map_inc_with_uref(raw); 40 break; 41 case BPF_TYPE_LINK: 42 bpf_link_inc(raw); 43 break; 44 default: 45 WARN_ON_ONCE(1); 46 break; 47 } 48 49 return raw; 50 } 51 52 static void bpf_any_put(void *raw, enum bpf_type type) 53 { 54 switch (type) { 55 case BPF_TYPE_PROG: 56 bpf_prog_put(raw); 57 break; 58 case BPF_TYPE_MAP: 59 bpf_map_put_with_uref(raw); 60 break; 61 case BPF_TYPE_LINK: 62 bpf_link_put(raw); 63 break; 64 default: 65 WARN_ON_ONCE(1); 66 break; 67 } 68 } 69 70 static void *bpf_fd_probe_obj(u32 ufd, enum bpf_type *type) 71 { 72 void *raw; 73 74 raw = bpf_map_get_with_uref(ufd); 75 if (!IS_ERR(raw)) { 76 *type = BPF_TYPE_MAP; 77 return raw; 78 } 79 80 raw = bpf_prog_get(ufd); 81 if (!IS_ERR(raw)) { 82 *type = BPF_TYPE_PROG; 83 return raw; 84 } 85 86 raw = bpf_link_get_from_fd(ufd); 87 if (!IS_ERR(raw)) { 88 *type = BPF_TYPE_LINK; 89 return raw; 90 } 91 92 return ERR_PTR(-EINVAL); 93 } 94 95 static const struct inode_operations bpf_dir_iops; 96 97 static const struct inode_operations bpf_prog_iops = { }; 98 static const struct inode_operations bpf_map_iops = { }; 99 static const struct inode_operations bpf_link_iops = { }; 100 101 static struct inode *bpf_get_inode(struct super_block *sb, 102 const struct inode *dir, 103 umode_t mode) 104 { 105 struct inode *inode; 106 107 switch (mode & S_IFMT) { 108 case S_IFDIR: 109 case S_IFREG: 110 case S_IFLNK: 111 break; 112 default: 113 return ERR_PTR(-EINVAL); 114 } 115 116 inode = new_inode(sb); 117 if (!inode) 118 return ERR_PTR(-ENOSPC); 119 120 inode->i_ino = get_next_ino(); 121 inode->i_atime = current_time(inode); 122 inode->i_mtime = inode->i_atime; 123 inode->i_ctime = inode->i_atime; 124 125 inode_init_owner(&init_user_ns, inode, dir, mode); 126 127 return inode; 128 } 129 130 static int bpf_inode_type(const struct inode *inode, enum bpf_type *type) 131 { 132 *type = BPF_TYPE_UNSPEC; 133 if (inode->i_op == &bpf_prog_iops) 134 *type = BPF_TYPE_PROG; 135 else if (inode->i_op == &bpf_map_iops) 136 *type = BPF_TYPE_MAP; 137 else if (inode->i_op == &bpf_link_iops) 138 *type = BPF_TYPE_LINK; 139 else 140 return -EACCES; 141 142 return 0; 143 } 144 145 static void bpf_dentry_finalize(struct dentry *dentry, struct inode *inode, 146 struct inode *dir) 147 { 148 d_instantiate(dentry, inode); 149 dget(dentry); 150 151 dir->i_mtime = current_time(dir); 152 dir->i_ctime = dir->i_mtime; 153 } 154 155 static int bpf_mkdir(struct user_namespace *mnt_userns, struct inode *dir, 156 struct dentry *dentry, umode_t mode) 157 { 158 struct inode *inode; 159 160 inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFDIR); 161 if (IS_ERR(inode)) 162 return PTR_ERR(inode); 163 164 inode->i_op = &bpf_dir_iops; 165 inode->i_fop = &simple_dir_operations; 166 167 inc_nlink(inode); 168 inc_nlink(dir); 169 170 bpf_dentry_finalize(dentry, inode, dir); 171 return 0; 172 } 173 174 struct map_iter { 175 void *key; 176 bool done; 177 }; 178 179 static struct map_iter *map_iter(struct seq_file *m) 180 { 181 return m->private; 182 } 183 184 static struct bpf_map *seq_file_to_map(struct seq_file *m) 185 { 186 return file_inode(m->file)->i_private; 187 } 188 189 static void map_iter_free(struct map_iter *iter) 190 { 191 if (iter) { 192 kfree(iter->key); 193 kfree(iter); 194 } 195 } 196 197 static struct map_iter *map_iter_alloc(struct bpf_map *map) 198 { 199 struct map_iter *iter; 200 201 iter = kzalloc(sizeof(*iter), GFP_KERNEL | __GFP_NOWARN); 202 if (!iter) 203 goto error; 204 205 iter->key = kzalloc(map->key_size, GFP_KERNEL | __GFP_NOWARN); 206 if (!iter->key) 207 goto error; 208 209 return iter; 210 211 error: 212 map_iter_free(iter); 213 return NULL; 214 } 215 216 static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos) 217 { 218 struct bpf_map *map = seq_file_to_map(m); 219 void *key = map_iter(m)->key; 220 void *prev_key; 221 222 (*pos)++; 223 if (map_iter(m)->done) 224 return NULL; 225 226 if (unlikely(v == SEQ_START_TOKEN)) 227 prev_key = NULL; 228 else 229 prev_key = key; 230 231 rcu_read_lock(); 232 if (map->ops->map_get_next_key(map, prev_key, key)) { 233 map_iter(m)->done = true; 234 key = NULL; 235 } 236 rcu_read_unlock(); 237 return key; 238 } 239 240 static void *map_seq_start(struct seq_file *m, loff_t *pos) 241 { 242 if (map_iter(m)->done) 243 return NULL; 244 245 return *pos ? map_iter(m)->key : SEQ_START_TOKEN; 246 } 247 248 static void map_seq_stop(struct seq_file *m, void *v) 249 { 250 } 251 252 static int map_seq_show(struct seq_file *m, void *v) 253 { 254 struct bpf_map *map = seq_file_to_map(m); 255 void *key = map_iter(m)->key; 256 257 if (unlikely(v == SEQ_START_TOKEN)) { 258 seq_puts(m, "# WARNING!! The output is for debug purpose only\n"); 259 seq_puts(m, "# WARNING!! The output format will change\n"); 260 } else { 261 map->ops->map_seq_show_elem(map, key, m); 262 } 263 264 return 0; 265 } 266 267 static const struct seq_operations bpffs_map_seq_ops = { 268 .start = map_seq_start, 269 .next = map_seq_next, 270 .show = map_seq_show, 271 .stop = map_seq_stop, 272 }; 273 274 static int bpffs_map_open(struct inode *inode, struct file *file) 275 { 276 struct bpf_map *map = inode->i_private; 277 struct map_iter *iter; 278 struct seq_file *m; 279 int err; 280 281 iter = map_iter_alloc(map); 282 if (!iter) 283 return -ENOMEM; 284 285 err = seq_open(file, &bpffs_map_seq_ops); 286 if (err) { 287 map_iter_free(iter); 288 return err; 289 } 290 291 m = file->private_data; 292 m->private = iter; 293 294 return 0; 295 } 296 297 static int bpffs_map_release(struct inode *inode, struct file *file) 298 { 299 struct seq_file *m = file->private_data; 300 301 map_iter_free(map_iter(m)); 302 303 return seq_release(inode, file); 304 } 305 306 /* bpffs_map_fops should only implement the basic 307 * read operation for a BPF map. The purpose is to 308 * provide a simple user intuitive way to do 309 * "cat bpffs/pathto/a-pinned-map". 310 * 311 * Other operations (e.g. write, lookup...) should be realized by 312 * the userspace tools (e.g. bpftool) through the 313 * BPF_OBJ_GET_INFO_BY_FD and the map's lookup/update 314 * interface. 315 */ 316 static const struct file_operations bpffs_map_fops = { 317 .open = bpffs_map_open, 318 .read = seq_read, 319 .release = bpffs_map_release, 320 }; 321 322 static int bpffs_obj_open(struct inode *inode, struct file *file) 323 { 324 return -EIO; 325 } 326 327 static const struct file_operations bpffs_obj_fops = { 328 .open = bpffs_obj_open, 329 }; 330 331 static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw, 332 const struct inode_operations *iops, 333 const struct file_operations *fops) 334 { 335 struct inode *dir = dentry->d_parent->d_inode; 336 struct inode *inode = bpf_get_inode(dir->i_sb, dir, mode); 337 if (IS_ERR(inode)) 338 return PTR_ERR(inode); 339 340 inode->i_op = iops; 341 inode->i_fop = fops; 342 inode->i_private = raw; 343 344 bpf_dentry_finalize(dentry, inode, dir); 345 return 0; 346 } 347 348 static int bpf_mkprog(struct dentry *dentry, umode_t mode, void *arg) 349 { 350 return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops, 351 &bpffs_obj_fops); 352 } 353 354 static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg) 355 { 356 struct bpf_map *map = arg; 357 358 return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops, 359 bpf_map_support_seq_show(map) ? 360 &bpffs_map_fops : &bpffs_obj_fops); 361 } 362 363 static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg) 364 { 365 struct bpf_link *link = arg; 366 367 return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops, 368 bpf_link_is_iter(link) ? 369 &bpf_iter_fops : &bpffs_obj_fops); 370 } 371 372 static struct dentry * 373 bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags) 374 { 375 /* Dots in names (e.g. "/sys/fs/bpf/foo.bar") are reserved for future 376 * extensions. That allows popoulate_bpffs() create special files. 377 */ 378 if ((dir->i_mode & S_IALLUGO) && 379 strchr(dentry->d_name.name, '.')) 380 return ERR_PTR(-EPERM); 381 382 return simple_lookup(dir, dentry, flags); 383 } 384 385 static int bpf_symlink(struct user_namespace *mnt_userns, struct inode *dir, 386 struct dentry *dentry, const char *target) 387 { 388 char *link = kstrdup(target, GFP_USER | __GFP_NOWARN); 389 struct inode *inode; 390 391 if (!link) 392 return -ENOMEM; 393 394 inode = bpf_get_inode(dir->i_sb, dir, S_IRWXUGO | S_IFLNK); 395 if (IS_ERR(inode)) { 396 kfree(link); 397 return PTR_ERR(inode); 398 } 399 400 inode->i_op = &simple_symlink_inode_operations; 401 inode->i_link = link; 402 403 bpf_dentry_finalize(dentry, inode, dir); 404 return 0; 405 } 406 407 static const struct inode_operations bpf_dir_iops = { 408 .lookup = bpf_lookup, 409 .mkdir = bpf_mkdir, 410 .symlink = bpf_symlink, 411 .rmdir = simple_rmdir, 412 .rename = simple_rename, 413 .link = simple_link, 414 .unlink = simple_unlink, 415 }; 416 417 /* pin iterator link into bpffs */ 418 static int bpf_iter_link_pin_kernel(struct dentry *parent, 419 const char *name, struct bpf_link *link) 420 { 421 umode_t mode = S_IFREG | S_IRUSR; 422 struct dentry *dentry; 423 int ret; 424 425 inode_lock(parent->d_inode); 426 dentry = lookup_one_len(name, parent, strlen(name)); 427 if (IS_ERR(dentry)) { 428 inode_unlock(parent->d_inode); 429 return PTR_ERR(dentry); 430 } 431 ret = bpf_mkobj_ops(dentry, mode, link, &bpf_link_iops, 432 &bpf_iter_fops); 433 dput(dentry); 434 inode_unlock(parent->d_inode); 435 return ret; 436 } 437 438 static int bpf_obj_do_pin(const char __user *pathname, void *raw, 439 enum bpf_type type) 440 { 441 struct dentry *dentry; 442 struct inode *dir; 443 struct path path; 444 umode_t mode; 445 int ret; 446 447 dentry = user_path_create(AT_FDCWD, pathname, &path, 0); 448 if (IS_ERR(dentry)) 449 return PTR_ERR(dentry); 450 451 mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask()); 452 453 ret = security_path_mknod(&path, dentry, mode, 0); 454 if (ret) 455 goto out; 456 457 dir = d_inode(path.dentry); 458 if (dir->i_op != &bpf_dir_iops) { 459 ret = -EPERM; 460 goto out; 461 } 462 463 switch (type) { 464 case BPF_TYPE_PROG: 465 ret = vfs_mkobj(dentry, mode, bpf_mkprog, raw); 466 break; 467 case BPF_TYPE_MAP: 468 ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw); 469 break; 470 case BPF_TYPE_LINK: 471 ret = vfs_mkobj(dentry, mode, bpf_mklink, raw); 472 break; 473 default: 474 ret = -EPERM; 475 } 476 out: 477 done_path_create(&path, dentry); 478 return ret; 479 } 480 481 int bpf_obj_pin_user(u32 ufd, const char __user *pathname) 482 { 483 enum bpf_type type; 484 void *raw; 485 int ret; 486 487 raw = bpf_fd_probe_obj(ufd, &type); 488 if (IS_ERR(raw)) 489 return PTR_ERR(raw); 490 491 ret = bpf_obj_do_pin(pathname, raw, type); 492 if (ret != 0) 493 bpf_any_put(raw, type); 494 495 return ret; 496 } 497 498 static void *bpf_obj_do_get(const char __user *pathname, 499 enum bpf_type *type, int flags) 500 { 501 struct inode *inode; 502 struct path path; 503 void *raw; 504 int ret; 505 506 ret = user_path_at(AT_FDCWD, pathname, LOOKUP_FOLLOW, &path); 507 if (ret) 508 return ERR_PTR(ret); 509 510 inode = d_backing_inode(path.dentry); 511 ret = path_permission(&path, ACC_MODE(flags)); 512 if (ret) 513 goto out; 514 515 ret = bpf_inode_type(inode, type); 516 if (ret) 517 goto out; 518 519 raw = bpf_any_get(inode->i_private, *type); 520 if (!IS_ERR(raw)) 521 touch_atime(&path); 522 523 path_put(&path); 524 return raw; 525 out: 526 path_put(&path); 527 return ERR_PTR(ret); 528 } 529 530 int bpf_obj_get_user(const char __user *pathname, int flags) 531 { 532 enum bpf_type type = BPF_TYPE_UNSPEC; 533 int f_flags; 534 void *raw; 535 int ret; 536 537 f_flags = bpf_get_file_flag(flags); 538 if (f_flags < 0) 539 return f_flags; 540 541 raw = bpf_obj_do_get(pathname, &type, f_flags); 542 if (IS_ERR(raw)) 543 return PTR_ERR(raw); 544 545 if (type == BPF_TYPE_PROG) 546 ret = bpf_prog_new_fd(raw); 547 else if (type == BPF_TYPE_MAP) 548 ret = bpf_map_new_fd(raw, f_flags); 549 else if (type == BPF_TYPE_LINK) 550 ret = (f_flags != O_RDWR) ? -EINVAL : bpf_link_new_fd(raw); 551 else 552 return -ENOENT; 553 554 if (ret < 0) 555 bpf_any_put(raw, type); 556 return ret; 557 } 558 559 static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type type) 560 { 561 struct bpf_prog *prog; 562 int ret = inode_permission(&init_user_ns, inode, MAY_READ); 563 if (ret) 564 return ERR_PTR(ret); 565 566 if (inode->i_op == &bpf_map_iops) 567 return ERR_PTR(-EINVAL); 568 if (inode->i_op == &bpf_link_iops) 569 return ERR_PTR(-EINVAL); 570 if (inode->i_op != &bpf_prog_iops) 571 return ERR_PTR(-EACCES); 572 573 prog = inode->i_private; 574 575 ret = security_bpf_prog(prog); 576 if (ret < 0) 577 return ERR_PTR(ret); 578 579 if (!bpf_prog_get_ok(prog, &type, false)) 580 return ERR_PTR(-EINVAL); 581 582 bpf_prog_inc(prog); 583 return prog; 584 } 585 586 struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type) 587 { 588 struct bpf_prog *prog; 589 struct path path; 590 int ret = kern_path(name, LOOKUP_FOLLOW, &path); 591 if (ret) 592 return ERR_PTR(ret); 593 prog = __get_prog_inode(d_backing_inode(path.dentry), type); 594 if (!IS_ERR(prog)) 595 touch_atime(&path); 596 path_put(&path); 597 return prog; 598 } 599 EXPORT_SYMBOL(bpf_prog_get_type_path); 600 601 /* 602 * Display the mount options in /proc/mounts. 603 */ 604 static int bpf_show_options(struct seq_file *m, struct dentry *root) 605 { 606 umode_t mode = d_inode(root)->i_mode & S_IALLUGO & ~S_ISVTX; 607 608 if (mode != S_IRWXUGO) 609 seq_printf(m, ",mode=%o", mode); 610 return 0; 611 } 612 613 static void bpf_free_inode(struct inode *inode) 614 { 615 enum bpf_type type; 616 617 if (S_ISLNK(inode->i_mode)) 618 kfree(inode->i_link); 619 if (!bpf_inode_type(inode, &type)) 620 bpf_any_put(inode->i_private, type); 621 free_inode_nonrcu(inode); 622 } 623 624 static const struct super_operations bpf_super_ops = { 625 .statfs = simple_statfs, 626 .drop_inode = generic_delete_inode, 627 .show_options = bpf_show_options, 628 .free_inode = bpf_free_inode, 629 }; 630 631 enum { 632 OPT_MODE, 633 }; 634 635 static const struct fs_parameter_spec bpf_fs_parameters[] = { 636 fsparam_u32oct ("mode", OPT_MODE), 637 {} 638 }; 639 640 struct bpf_mount_opts { 641 umode_t mode; 642 }; 643 644 static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param) 645 { 646 struct bpf_mount_opts *opts = fc->fs_private; 647 struct fs_parse_result result; 648 int opt; 649 650 opt = fs_parse(fc, bpf_fs_parameters, param, &result); 651 if (opt < 0) { 652 /* We might like to report bad mount options here, but 653 * traditionally we've ignored all mount options, so we'd 654 * better continue to ignore non-existing options for bpf. 655 */ 656 if (opt == -ENOPARAM) { 657 opt = vfs_parse_fs_param_source(fc, param); 658 if (opt != -ENOPARAM) 659 return opt; 660 661 return 0; 662 } 663 664 if (opt < 0) 665 return opt; 666 } 667 668 switch (opt) { 669 case OPT_MODE: 670 opts->mode = result.uint_32 & S_IALLUGO; 671 break; 672 } 673 674 return 0; 675 } 676 677 struct bpf_preload_ops *bpf_preload_ops; 678 EXPORT_SYMBOL_GPL(bpf_preload_ops); 679 680 static bool bpf_preload_mod_get(void) 681 { 682 /* If bpf_preload.ko wasn't loaded earlier then load it now. 683 * When bpf_preload is built into vmlinux the module's __init 684 * function will populate it. 685 */ 686 if (!bpf_preload_ops) { 687 request_module("bpf_preload"); 688 if (!bpf_preload_ops) 689 return false; 690 } 691 /* And grab the reference, so the module doesn't disappear while the 692 * kernel is interacting with the kernel module and its UMD. 693 */ 694 if (!try_module_get(bpf_preload_ops->owner)) { 695 pr_err("bpf_preload module get failed.\n"); 696 return false; 697 } 698 return true; 699 } 700 701 static void bpf_preload_mod_put(void) 702 { 703 if (bpf_preload_ops) 704 /* now user can "rmmod bpf_preload" if necessary */ 705 module_put(bpf_preload_ops->owner); 706 } 707 708 static DEFINE_MUTEX(bpf_preload_lock); 709 710 static int populate_bpffs(struct dentry *parent) 711 { 712 struct bpf_preload_info objs[BPF_PRELOAD_LINKS] = {}; 713 int err = 0, i; 714 715 /* grab the mutex to make sure the kernel interactions with bpf_preload 716 * are serialized 717 */ 718 mutex_lock(&bpf_preload_lock); 719 720 /* if bpf_preload.ko wasn't built into vmlinux then load it */ 721 if (!bpf_preload_mod_get()) 722 goto out; 723 724 err = bpf_preload_ops->preload(objs); 725 if (err) 726 goto out_put; 727 for (i = 0; i < BPF_PRELOAD_LINKS; i++) { 728 bpf_link_inc(objs[i].link); 729 err = bpf_iter_link_pin_kernel(parent, 730 objs[i].link_name, objs[i].link); 731 if (err) { 732 bpf_link_put(objs[i].link); 733 goto out_put; 734 } 735 } 736 out_put: 737 bpf_preload_mod_put(); 738 out: 739 mutex_unlock(&bpf_preload_lock); 740 return err; 741 } 742 743 static int bpf_fill_super(struct super_block *sb, struct fs_context *fc) 744 { 745 static const struct tree_descr bpf_rfiles[] = { { "" } }; 746 struct bpf_mount_opts *opts = fc->fs_private; 747 struct inode *inode; 748 int ret; 749 750 ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles); 751 if (ret) 752 return ret; 753 754 sb->s_op = &bpf_super_ops; 755 756 inode = sb->s_root->d_inode; 757 inode->i_op = &bpf_dir_iops; 758 inode->i_mode &= ~S_IALLUGO; 759 populate_bpffs(sb->s_root); 760 inode->i_mode |= S_ISVTX | opts->mode; 761 return 0; 762 } 763 764 static int bpf_get_tree(struct fs_context *fc) 765 { 766 return get_tree_nodev(fc, bpf_fill_super); 767 } 768 769 static void bpf_free_fc(struct fs_context *fc) 770 { 771 kfree(fc->fs_private); 772 } 773 774 static const struct fs_context_operations bpf_context_ops = { 775 .free = bpf_free_fc, 776 .parse_param = bpf_parse_param, 777 .get_tree = bpf_get_tree, 778 }; 779 780 /* 781 * Set up the filesystem mount context. 782 */ 783 static int bpf_init_fs_context(struct fs_context *fc) 784 { 785 struct bpf_mount_opts *opts; 786 787 opts = kzalloc(sizeof(struct bpf_mount_opts), GFP_KERNEL); 788 if (!opts) 789 return -ENOMEM; 790 791 opts->mode = S_IRWXUGO; 792 793 fc->fs_private = opts; 794 fc->ops = &bpf_context_ops; 795 return 0; 796 } 797 798 static struct file_system_type bpf_fs_type = { 799 .owner = THIS_MODULE, 800 .name = "bpf", 801 .init_fs_context = bpf_init_fs_context, 802 .parameters = bpf_fs_parameters, 803 .kill_sb = kill_litter_super, 804 }; 805 806 static int __init bpf_init(void) 807 { 808 int ret; 809 810 ret = sysfs_create_mount_point(fs_kobj, "bpf"); 811 if (ret) 812 return ret; 813 814 ret = register_filesystem(&bpf_fs_type); 815 if (ret) 816 sysfs_remove_mount_point(fs_kobj, "bpf"); 817 818 return ret; 819 } 820 fs_initcall(bpf_init); 821