kernel/bpf/inode.c

   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 <linux/kstrtox.h>
  24 #include "preload/bpf_preload.h"
  25
  26 enum bpf_type {
  27         BPF_TYPE_UNSPEC = 0,
  28         BPF_TYPE_PROG,
  29         BPF_TYPE_MAP,
  30         BPF_TYPE_LINK,
  31 };
  32
  33 static void *bpf_any_get(void *raw, enum bpf_type type)
  34 {
  35         switch (type) {
  36         case BPF_TYPE_PROG:
  37                 bpf_prog_inc(raw);
  38                 break;
  39         case BPF_TYPE_MAP:
  40                 bpf_map_inc_with_uref(raw);
  41                 break;
  42         case BPF_TYPE_LINK:
  43                 bpf_link_inc(raw);
  44                 break;
  45         default:
  46                 WARN_ON_ONCE(1);
  47                 break;
  48         }
  49
  50         return raw;
  51 }
  52
  53 static void bpf_any_put(void *raw, enum bpf_type type)
  54 {
  55         switch (type) {
  56         case BPF_TYPE_PROG:
  57                 bpf_prog_put(raw);
  58                 break;
  59         case BPF_TYPE_MAP:
  60                 bpf_map_put_with_uref(raw);
  61                 break;
  62         case BPF_TYPE_LINK:
  63                 bpf_link_put(raw);
  64                 break;
  65         default:
  66                 WARN_ON_ONCE(1);
  67                 break;
  68         }
  69 }
  70
  71 static void *bpf_fd_probe_obj(u32 ufd, enum bpf_type *type)
  72 {
  73         void *raw;
  74
  75         raw = bpf_map_get_with_uref(ufd);
  76         if (!IS_ERR(raw)) {
  77                 *type = BPF_TYPE_MAP;
  78                 return raw;
  79         }
  80
  81         raw = bpf_prog_get(ufd);
  82         if (!IS_ERR(raw)) {
  83                 *type = BPF_TYPE_PROG;
  84                 return raw;
  85         }
  86
  87         raw = bpf_link_get_from_fd(ufd);
  88         if (!IS_ERR(raw)) {
  89                 *type = BPF_TYPE_LINK;
  90                 return raw;
  91         }
  92
  93         return ERR_PTR(-EINVAL);
  94 }
  95
  96 static const struct inode_operations bpf_dir_iops;
  97
  98 static const struct inode_operations bpf_prog_iops = { };
  99 static const struct inode_operations bpf_map_iops  = { };
 100 static const struct inode_operations bpf_link_iops  = { };
 101
 102 struct inode *bpf_get_inode(struct super_block *sb,
 103                             const struct inode *dir,
 104                             umode_t mode)
 105 {
 106         struct inode *inode;
 107
 108         switch (mode & S_IFMT) {
 109         case S_IFDIR:
 110         case S_IFREG:
 111         case S_IFLNK:
 112                 break;
 113         default:
 114                 return ERR_PTR(-EINVAL);
 115         }
 116
 117         inode = new_inode(sb);
 118         if (!inode)
 119                 return ERR_PTR(-ENOSPC);
 120
 121         inode->i_ino = get_next_ino();
 122         simple_inode_init_ts(inode);
 123
 124         inode_init_owner(&nop_mnt_idmap, inode, dir, mode);
 125
 126         return inode;
 127 }
 128
 129 static int bpf_inode_type(const struct inode *inode, enum bpf_type *type)
 130 {
 131         *type = BPF_TYPE_UNSPEC;
 132         if (inode->i_op == &bpf_prog_iops)
 133                 *type = BPF_TYPE_PROG;
 134         else if (inode->i_op == &bpf_map_iops)
 135                 *type = BPF_TYPE_MAP;
 136         else if (inode->i_op == &bpf_link_iops)
 137                 *type = BPF_TYPE_LINK;
 138         else
 139                 return -EACCES;
 140
 141         return 0;
 142 }
 143
 144 static void bpf_dentry_finalize(struct dentry *dentry, struct inode *inode,
 145                                 struct inode *dir)
 146 {
 147         d_instantiate(dentry, inode);
 148         dget(dentry);
 149
 150         inode_set_mtime_to_ts(dir, inode_set_ctime_current(dir));
 151 }
 152
 153 static int bpf_mkdir(struct mnt_idmap *idmap, struct inode *dir,
 154                      struct dentry *dentry, umode_t mode)
 155 {
 156         struct inode *inode;
 157
 158         inode = bpf_get_inode(dir->i_sb, dir, mode | S_IFDIR);
 159         if (IS_ERR(inode))
 160                 return PTR_ERR(inode);
 161
 162         inode->i_op = &bpf_dir_iops;
 163         inode->i_fop = &simple_dir_operations;
 164
 165         inc_nlink(inode);
 166         inc_nlink(dir);
 167
 168         bpf_dentry_finalize(dentry, inode, dir);
 169         return 0;
 170 }
 171
 172 struct map_iter {
 173         void *key;
 174         bool done;
 175 };
 176
 177 static struct map_iter *map_iter(struct seq_file *m)
 178 {
 179         return m->private;
 180 }
 181
 182 static struct bpf_map *seq_file_to_map(struct seq_file *m)
 183 {
 184         return file_inode(m->file)->i_private;
 185 }
 186
 187 static void map_iter_free(struct map_iter *iter)
 188 {
 189         if (iter) {
 190                 kfree(iter->key);
 191                 kfree(iter);
 192         }
 193 }
 194
 195 static struct map_iter *map_iter_alloc(struct bpf_map *map)
 196 {
 197         struct map_iter *iter;
 198
 199         iter = kzalloc(sizeof(*iter), GFP_KERNEL | __GFP_NOWARN);
 200         if (!iter)
 201                 goto error;
 202
 203         iter->key = kzalloc(map->key_size, GFP_KERNEL | __GFP_NOWARN);
 204         if (!iter->key)
 205                 goto error;
 206
 207         return iter;
 208
 209 error:
 210         map_iter_free(iter);
 211         return NULL;
 212 }
 213
 214 static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
 215 {
 216         struct bpf_map *map = seq_file_to_map(m);
 217         void *key = map_iter(m)->key;
 218         void *prev_key;
 219
 220         (*pos)++;
 221         if (map_iter(m)->done)
 222                 return NULL;
 223
 224         if (unlikely(v == SEQ_START_TOKEN))
 225                 prev_key = NULL;
 226         else
 227                 prev_key = key;
 228
 229         rcu_read_lock();
 230         if (map->ops->map_get_next_key(map, prev_key, key)) {
 231                 map_iter(m)->done = true;
 232                 key = NULL;
 233         }
 234         rcu_read_unlock();
 235         return key;
 236 }
 237
 238 static void *map_seq_start(struct seq_file *m, loff_t *pos)
 239 {
 240         if (map_iter(m)->done)
 241                 return NULL;
 242
 243         return *pos ? map_iter(m)->key : SEQ_START_TOKEN;
 244 }
 245
 246 static void map_seq_stop(struct seq_file *m, void *v)
 247 {
 248 }
 249
 250 static int map_seq_show(struct seq_file *m, void *v)
 251 {
 252         struct bpf_map *map = seq_file_to_map(m);
 253         void *key = map_iter(m)->key;
 254
 255         if (unlikely(v == SEQ_START_TOKEN)) {
 256                 seq_puts(m, "# WARNING!! The output is for debug purpose only\n");
 257                 seq_puts(m, "# WARNING!! The output format will change\n");
 258         } else {
 259                 map->ops->map_seq_show_elem(map, key, m);
 260         }
 261
 262         return 0;
 263 }
 264
 265 static const struct seq_operations bpffs_map_seq_ops = {
 266         .start  = map_seq_start,
 267         .next   = map_seq_next,
 268         .show   = map_seq_show,
 269         .stop   = map_seq_stop,
 270 };
 271
 272 static int bpffs_map_open(struct inode *inode, struct file *file)
 273 {
 274         struct bpf_map *map = inode->i_private;
 275         struct map_iter *iter;
 276         struct seq_file *m;
 277         int err;
 278
 279         iter = map_iter_alloc(map);
 280         if (!iter)
 281                 return -ENOMEM;
 282
 283         err = seq_open(file, &bpffs_map_seq_ops);
 284         if (err) {
 285                 map_iter_free(iter);
 286                 return err;
 287         }
 288
 289         m = file->private_data;
 290         m->private = iter;
 291
 292         return 0;
 293 }
 294
 295 static int bpffs_map_release(struct inode *inode, struct file *file)
 296 {
 297         struct seq_file *m = file->private_data;
 298
 299         map_iter_free(map_iter(m));
 300
 301         return seq_release(inode, file);
 302 }
 303
 304 /* bpffs_map_fops should only implement the basic
 305  * read operation for a BPF map.  The purpose is to
 306  * provide a simple user intuitive way to do
 307  * "cat bpffs/pathto/a-pinned-map".
 308  *
 309  * Other operations (e.g. write, lookup...) should be realized by
 310  * the userspace tools (e.g. bpftool) through the
 311  * BPF_OBJ_GET_INFO_BY_FD and the map's lookup/update
 312  * interface.
 313  */
 314 static const struct file_operations bpffs_map_fops = {
 315         .open           = bpffs_map_open,
 316         .read           = seq_read,
 317         .release        = bpffs_map_release,
 318 };
 319
 320 static int bpffs_obj_open(struct inode *inode, struct file *file)
 321 {
 322         return -EIO;
 323 }
 324
 325 static const struct file_operations bpffs_obj_fops = {
 326         .open           = bpffs_obj_open,
 327 };
 328
 329 static int bpf_mkobj_ops(struct dentry *dentry, umode_t mode, void *raw,
 330                          const struct inode_operations *iops,
 331                          const struct file_operations *fops)
 332 {
 333         struct inode *dir = dentry->d_parent->d_inode;
 334         struct inode *inode = bpf_get_inode(dir->i_sb, dir, mode);
 335         if (IS_ERR(inode))
 336                 return PTR_ERR(inode);
 337
 338         inode->i_op = iops;
 339         inode->i_fop = fops;
 340         inode->i_private = raw;
 341
 342         bpf_dentry_finalize(dentry, inode, dir);
 343         return 0;
 344 }
 345
 346 static int bpf_mkprog(struct dentry *dentry, umode_t mode, void *arg)
 347 {
 348         return bpf_mkobj_ops(dentry, mode, arg, &bpf_prog_iops,
 349                              &bpffs_obj_fops);
 350 }
 351
 352 static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
 353 {
 354         struct bpf_map *map = arg;
 355
 356         return bpf_mkobj_ops(dentry, mode, arg, &bpf_map_iops,
 357                              bpf_map_support_seq_show(map) ?
 358                              &bpffs_map_fops : &bpffs_obj_fops);
 359 }
 360
 361 static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg)
 362 {
 363         struct bpf_link *link = arg;
 364
 365         return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops,
 366                              bpf_link_is_iter(link) ?
 367                              &bpf_iter_fops : &bpffs_obj_fops);
 368 }
 369
 370 static struct dentry *
 371 bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags)
 372 {
 373         /* Dots in names (e.g. "/sys/fs/bpf/foo.bar") are reserved for future
 374          * extensions. That allows popoulate_bpffs() create special files.
 375          */
 376         if ((dir->i_mode & S_IALLUGO) &&
 377             strchr(dentry->d_name.name, '.'))
 378                 return ERR_PTR(-EPERM);
 379
 380         return simple_lookup(dir, dentry, flags);
 381 }
 382
 383 static int bpf_symlink(struct mnt_idmap *idmap, struct inode *dir,
 384                        struct dentry *dentry, const char *target)
 385 {
 386         char *link = kstrdup(target, GFP_USER | __GFP_NOWARN);
 387         struct inode *inode;
 388
 389         if (!link)
 390                 return -ENOMEM;
 391
 392         inode = bpf_get_inode(dir->i_sb, dir, S_IRWXUGO | S_IFLNK);
 393         if (IS_ERR(inode)) {
 394                 kfree(link);
 395                 return PTR_ERR(inode);
 396         }
 397
 398         inode->i_op = &simple_symlink_inode_operations;
 399         inode->i_link = link;
 400
 401         bpf_dentry_finalize(dentry, inode, dir);
 402         return 0;
 403 }
 404
 405 static const struct inode_operations bpf_dir_iops = {
 406         .lookup         = bpf_lookup,
 407         .mkdir          = bpf_mkdir,
 408         .symlink        = bpf_symlink,
 409         .rmdir          = simple_rmdir,
 410         .rename         = simple_rename,
 411         .link           = simple_link,
 412         .unlink         = simple_unlink,
 413 };
 414
 415 /* pin iterator link into bpffs */
 416 static int bpf_iter_link_pin_kernel(struct dentry *parent,
 417                                     const char *name, struct bpf_link *link)
 418 {
 419         umode_t mode = S_IFREG | S_IRUSR;
 420         struct dentry *dentry;
 421         int ret;
 422
 423         inode_lock(parent->d_inode);
 424         dentry = lookup_one_len(name, parent, strlen(name));
 425         if (IS_ERR(dentry)) {
 426                 inode_unlock(parent->d_inode);
 427                 return PTR_ERR(dentry);
 428         }
 429         ret = bpf_mkobj_ops(dentry, mode, link, &bpf_link_iops,
 430                             &bpf_iter_fops);
 431         dput(dentry);
 432         inode_unlock(parent->d_inode);
 433         return ret;
 434 }
 435
 436 static int bpf_obj_do_pin(int path_fd, const char __user *pathname, void *raw,
 437                           enum bpf_type type)
 438 {
 439         struct dentry *dentry;
 440         struct inode *dir;
 441         struct path path;
 442         umode_t mode;
 443         int ret;
 444
 445         dentry = user_path_create(path_fd, pathname, &path, 0);
 446         if (IS_ERR(dentry))
 447                 return PTR_ERR(dentry);
 448
 449         dir = d_inode(path.dentry);
 450         if (dir->i_op != &bpf_dir_iops) {
 451                 ret = -EPERM;
 452                 goto out;
 453         }
 454
 455         mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
 456         ret = security_path_mknod(&path, dentry, mode, 0);
 457         if (ret)
 458                 goto out;
 459
 460         switch (type) {
 461         case BPF_TYPE_PROG:
 462                 ret = vfs_mkobj(dentry, mode, bpf_mkprog, raw);
 463                 break;
 464         case BPF_TYPE_MAP:
 465                 ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw);
 466                 break;
 467         case BPF_TYPE_LINK:
 468                 ret = vfs_mkobj(dentry, mode, bpf_mklink, raw);
 469                 break;
 470         default:
 471                 ret = -EPERM;
 472         }
 473 out:
 474         done_path_create(&path, dentry);
 475         return ret;
 476 }
 477
 478 int bpf_obj_pin_user(u32 ufd, int path_fd, const char __user *pathname)
 479 {
 480         enum bpf_type type;
 481         void *raw;
 482         int ret;
 483
 484         raw = bpf_fd_probe_obj(ufd, &type);
 485         if (IS_ERR(raw))
 486                 return PTR_ERR(raw);
 487
 488         ret = bpf_obj_do_pin(path_fd, pathname, raw, type);
 489         if (ret != 0)
 490                 bpf_any_put(raw, type);
 491
 492         return ret;
 493 }
 494
 495 static void *bpf_obj_do_get(int path_fd, const char __user *pathname,
 496                             enum bpf_type *type, int flags)
 497 {
 498         struct inode *inode;
 499         struct path path;
 500         void *raw;
 501         int ret;
 502
 503         ret = user_path_at(path_fd, pathname, LOOKUP_FOLLOW, &path);
 504         if (ret)
 505                 return ERR_PTR(ret);
 506
 507         inode = d_backing_inode(path.dentry);
 508         ret = path_permission(&path, ACC_MODE(flags));
 509         if (ret)
 510                 goto out;
 511
 512         ret = bpf_inode_type(inode, type);
 513         if (ret)
 514                 goto out;
 515
 516         raw = bpf_any_get(inode->i_private, *type);
 517         if (!IS_ERR(raw))
 518                 touch_atime(&path);
 519
 520         path_put(&path);
 521         return raw;
 522 out:
 523         path_put(&path);
 524         return ERR_PTR(ret);
 525 }
 526
 527 int bpf_obj_get_user(int path_fd, const char __user *pathname, int flags)
 528 {
 529         enum bpf_type type = BPF_TYPE_UNSPEC;
 530         int f_flags;
 531         void *raw;
 532         int ret;
 533
 534         f_flags = bpf_get_file_flag(flags);
 535         if (f_flags < 0)
 536                 return f_flags;
 537
 538         raw = bpf_obj_do_get(path_fd, pathname, &type, f_flags);
 539         if (IS_ERR(raw))
 540                 return PTR_ERR(raw);
 541
 542         if (type == BPF_TYPE_PROG)
 543                 ret = bpf_prog_new_fd(raw);
 544         else if (type == BPF_TYPE_MAP)
 545                 ret = bpf_map_new_fd(raw, f_flags);
 546         else if (type == BPF_TYPE_LINK)
 547                 ret = (f_flags != O_RDWR) ? -EINVAL : bpf_link_new_fd(raw);
 548         else
 549                 return -ENOENT;
 550
 551         if (ret < 0)
 552                 bpf_any_put(raw, type);
 553         return ret;
 554 }
 555
 556 static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type type)
 557 {
 558         struct bpf_prog *prog;
 559         int ret = inode_permission(&nop_mnt_idmap, inode, MAY_READ);
 560         if (ret)
 561                 return ERR_PTR(ret);
 562
 563         if (inode->i_op == &bpf_map_iops)
 564                 return ERR_PTR(-EINVAL);
 565         if (inode->i_op == &bpf_link_iops)
 566                 return ERR_PTR(-EINVAL);
 567         if (inode->i_op != &bpf_prog_iops)
 568                 return ERR_PTR(-EACCES);
 569
 570         prog = inode->i_private;
 571
 572         ret = security_bpf_prog(prog);
 573         if (ret < 0)
 574                 return ERR_PTR(ret);
 575
 576         if (!bpf_prog_get_ok(prog, &type, false))
 577                 return ERR_PTR(-EINVAL);
 578
 579         bpf_prog_inc(prog);
 580         return prog;
 581 }
 582
 583 struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type)
 584 {
 585         struct bpf_prog *prog;
 586         struct path path;
 587         int ret = kern_path(name, LOOKUP_FOLLOW, &path);
 588         if (ret)
 589                 return ERR_PTR(ret);
 590         prog = __get_prog_inode(d_backing_inode(path.dentry), type);
 591         if (!IS_ERR(prog))
 592                 touch_atime(&path);
 593         path_put(&path);
 594         return prog;
 595 }
 596 EXPORT_SYMBOL(bpf_prog_get_type_path);
 597
 598 struct bpffs_btf_enums {
 599         const struct btf *btf;
 600         const struct btf_type *cmd_t;
 601         const struct btf_type *map_t;
 602         const struct btf_type *prog_t;
 603         const struct btf_type *attach_t;
 604 };
 605
 606 static int find_bpffs_btf_enums(struct bpffs_btf_enums *info)
 607 {
 608         const struct btf *btf;
 609         const struct btf_type *t;
 610         const char *name;
 611         int i, n;
 612
 613         memset(info, 0, sizeof(*info));
 614
 615         btf = bpf_get_btf_vmlinux();
 616         if (IS_ERR(btf))
 617                 return PTR_ERR(btf);
 618         if (!btf)
 619                 return -ENOENT;
 620
 621         info->btf = btf;
 622
 623         for (i = 1, n = btf_nr_types(btf); i < n; i++) {
 624                 t = btf_type_by_id(btf, i);
 625                 if (!btf_type_is_enum(t))
 626                         continue;
 627
 628                 name = btf_name_by_offset(btf, t->name_off);
 629                 if (!name)
 630                         continue;
 631
 632                 if (strcmp(name, "bpf_cmd") == 0)
 633                         info->cmd_t = t;
 634                 else if (strcmp(name, "bpf_map_type") == 0)
 635                         info->map_t = t;
 636                 else if (strcmp(name, "bpf_prog_type") == 0)
 637                         info->prog_t = t;
 638                 else if (strcmp(name, "bpf_attach_type") == 0)
 639                         info->attach_t = t;
 640                 else
 641                         continue;
 642
 643                 if (info->cmd_t && info->map_t && info->prog_t && info->attach_t)
 644                         return 0;
 645         }
 646
 647         return -ESRCH;
 648 }
 649
 650 static bool find_btf_enum_const(const struct btf *btf, const struct btf_type *enum_t,
 651                                 const char *prefix, const char *str, int *value)
 652 {
 653         const struct btf_enum *e;
 654         const char *name;
 655         int i, n, pfx_len = strlen(prefix);
 656
 657         *value = 0;
 658
 659         if (!btf || !enum_t)
 660                 return false;
 661
 662         for (i = 0, n = btf_vlen(enum_t); i < n; i++) {
 663                 e = &btf_enum(enum_t)[i];
 664
 665                 name = btf_name_by_offset(btf, e->name_off);
 666                 if (!name || strncasecmp(name, prefix, pfx_len) != 0)
 667                         continue;
 668
 669                 /* match symbolic name case insensitive and ignoring prefix */
 670                 if (strcasecmp(name + pfx_len, str) == 0) {
 671                         *value = e->val;
 672                         return true;
 673                 }
 674         }
 675
 676         return false;
 677 }
 678
 679 static void seq_print_delegate_opts(struct seq_file *m,
 680                                     const char *opt_name,
 681                                     const struct btf *btf,
 682                                     const struct btf_type *enum_t,
 683                                     const char *prefix,
 684                                     u64 delegate_msk, u64 any_msk)
 685 {
 686         const struct btf_enum *e;
 687         bool first = true;
 688         const char *name;
 689         u64 msk;
 690         int i, n, pfx_len = strlen(prefix);
 691
 692         delegate_msk &= any_msk; /* clear unknown bits */
 693
 694         if (delegate_msk == 0)
 695                 return;
 696
 697         seq_printf(m, ",%s", opt_name);
 698         if (delegate_msk == any_msk) {
 699                 seq_printf(m, "=any");
 700                 return;
 701         }
 702
 703         if (btf && enum_t) {
 704                 for (i = 0, n = btf_vlen(enum_t); i < n; i++) {
 705                         e = &btf_enum(enum_t)[i];
 706                         name = btf_name_by_offset(btf, e->name_off);
 707                         if (!name || strncasecmp(name, prefix, pfx_len) != 0)
 708                                 continue;
 709                         msk = 1ULL << e->val;
 710                         if (delegate_msk & msk) {
 711                                 /* emit lower-case name without prefix */
 712                                 seq_putc(m, first ? '=' : ':');
 713                                 name += pfx_len;
 714                                 while (*name) {
 715                                         seq_putc(m, tolower(*name));
 716                                         name++;
 717                                 }
 718
 719                                 delegate_msk &= ~msk;
 720                                 first = false;
 721                         }
 722                 }
 723         }
 724         if (delegate_msk)
 725                 seq_printf(m, "%c0x%llx", first ? '=' : ':', delegate_msk);
 726 }
 727
 728 /*
 729  * Display the mount options in /proc/mounts.
 730  */
 731 static int bpf_show_options(struct seq_file *m, struct dentry *root)
 732 {
 733         struct inode *inode = d_inode(root);
 734         umode_t mode = inode->i_mode & S_IALLUGO & ~S_ISVTX;
 735         struct bpf_mount_opts *opts = root->d_sb->s_fs_info;
 736         u64 mask;
 737
 738         if (!uid_eq(inode->i_uid, GLOBAL_ROOT_UID))
 739                 seq_printf(m, ",uid=%u",
 740                            from_kuid_munged(&init_user_ns, inode->i_uid));
 741         if (!gid_eq(inode->i_gid, GLOBAL_ROOT_GID))
 742                 seq_printf(m, ",gid=%u",
 743                            from_kgid_munged(&init_user_ns, inode->i_gid));
 744         if (mode != S_IRWXUGO)
 745                 seq_printf(m, ",mode=%o", mode);
 746
 747         if (opts->delegate_cmds || opts->delegate_maps ||
 748             opts->delegate_progs || opts->delegate_attachs) {
 749                 struct bpffs_btf_enums info;
 750
 751                 /* ignore errors, fallback to hex */
 752                 (void)find_bpffs_btf_enums(&info);
 753
 754                 mask = (1ULL << __MAX_BPF_CMD) - 1;
 755                 seq_print_delegate_opts(m, "delegate_cmds",
 756                                         info.btf, info.cmd_t, "BPF_",
 757                                         opts->delegate_cmds, mask);
 758
 759                 mask = (1ULL << __MAX_BPF_MAP_TYPE) - 1;
 760                 seq_print_delegate_opts(m, "delegate_maps",
 761                                         info.btf, info.map_t, "BPF_MAP_TYPE_",
 762                                         opts->delegate_maps, mask);
 763
 764                 mask = (1ULL << __MAX_BPF_PROG_TYPE) - 1;
 765                 seq_print_delegate_opts(m, "delegate_progs",
 766                                         info.btf, info.prog_t, "BPF_PROG_TYPE_",
 767                                         opts->delegate_progs, mask);
 768
 769                 mask = (1ULL << __MAX_BPF_ATTACH_TYPE) - 1;
 770                 seq_print_delegate_opts(m, "delegate_attachs",
 771                                         info.btf, info.attach_t, "BPF_",
 772                                         opts->delegate_attachs, mask);
 773         }
 774
 775         return 0;
 776 }
 777
 778 static void bpf_free_inode(struct inode *inode)
 779 {
 780         enum bpf_type type;
 781
 782         if (S_ISLNK(inode->i_mode))
 783                 kfree(inode->i_link);
 784         if (!bpf_inode_type(inode, &type))
 785                 bpf_any_put(inode->i_private, type);
 786         free_inode_nonrcu(inode);
 787 }
 788
 789 const struct super_operations bpf_super_ops = {
 790         .statfs         = simple_statfs,
 791         .drop_inode     = generic_delete_inode,
 792         .show_options   = bpf_show_options,
 793         .free_inode     = bpf_free_inode,
 794 };
 795
 796 enum {
 797         OPT_UID,
 798         OPT_GID,
 799         OPT_MODE,
 800         OPT_DELEGATE_CMDS,
 801         OPT_DELEGATE_MAPS,
 802         OPT_DELEGATE_PROGS,
 803         OPT_DELEGATE_ATTACHS,
 804 };
 805
 806 static const struct fs_parameter_spec bpf_fs_parameters[] = {
 807         fsparam_u32     ("uid",                         OPT_UID),
 808         fsparam_u32     ("gid",                         OPT_GID),
 809         fsparam_u32oct  ("mode",                        OPT_MODE),
 810         fsparam_string  ("delegate_cmds",               OPT_DELEGATE_CMDS),
 811         fsparam_string  ("delegate_maps",               OPT_DELEGATE_MAPS),
 812         fsparam_string  ("delegate_progs",              OPT_DELEGATE_PROGS),
 813         fsparam_string  ("delegate_attachs",            OPT_DELEGATE_ATTACHS),
 814         {}
 815 };
 816
 817 static int bpf_parse_param(struct fs_context *fc, struct fs_parameter *param)
 818 {
 819         struct bpf_mount_opts *opts = fc->s_fs_info;
 820         struct fs_parse_result result;
 821         kuid_t uid;
 822         kgid_t gid;
 823         int opt, err;
 824
 825         opt = fs_parse(fc, bpf_fs_parameters, param, &result);
 826         if (opt < 0) {
 827                 /* We might like to report bad mount options here, but
 828                  * traditionally we've ignored all mount options, so we'd
 829                  * better continue to ignore non-existing options for bpf.
 830                  */
 831                 if (opt == -ENOPARAM) {
 832                         opt = vfs_parse_fs_param_source(fc, param);
 833                         if (opt != -ENOPARAM)
 834                                 return opt;
 835
 836                         return 0;
 837                 }
 838
 839                 if (opt < 0)
 840                         return opt;
 841         }
 842
 843         switch (opt) {
 844         case OPT_UID:
 845                 uid = make_kuid(current_user_ns(), result.uint_32);
 846                 if (!uid_valid(uid))
 847                         goto bad_value;
 848
 849                 /*
 850                  * The requested uid must be representable in the
 851                  * filesystem's idmapping.
 852                  */
 853                 if (!kuid_has_mapping(fc->user_ns, uid))
 854                         goto bad_value;
 855
 856                 opts->uid = uid;
 857                 break;
 858         case OPT_GID:
 859                 gid = make_kgid(current_user_ns(), result.uint_32);
 860                 if (!gid_valid(gid))
 861                         goto bad_value;
 862
 863                 /*
 864                  * The requested gid must be representable in the
 865                  * filesystem's idmapping.
 866                  */
 867                 if (!kgid_has_mapping(fc->user_ns, gid))
 868                         goto bad_value;
 869
 870                 opts->gid = gid;
 871                 break;
 872         case OPT_MODE:
 873                 opts->mode = result.uint_32 & S_IALLUGO;
 874                 break;
 875         case OPT_DELEGATE_CMDS:
 876         case OPT_DELEGATE_MAPS:
 877         case OPT_DELEGATE_PROGS:
 878         case OPT_DELEGATE_ATTACHS: {
 879                 struct bpffs_btf_enums info;
 880                 const struct btf_type *enum_t;
 881                 const char *enum_pfx;
 882                 u64 *delegate_msk, msk = 0;
 883                 char *p, *str;
 884                 int val;
 885
 886                 /* ignore errors, fallback to hex */
 887                 (void)find_bpffs_btf_enums(&info);
 888
 889                 switch (opt) {
 890                 case OPT_DELEGATE_CMDS:
 891                         delegate_msk = &opts->delegate_cmds;
 892                         enum_t = info.cmd_t;
 893                         enum_pfx = "BPF_";
 894                         break;
 895                 case OPT_DELEGATE_MAPS:
 896                         delegate_msk = &opts->delegate_maps;
 897                         enum_t = info.map_t;
 898                         enum_pfx = "BPF_MAP_TYPE_";
 899                         break;
 900                 case OPT_DELEGATE_PROGS:
 901                         delegate_msk = &opts->delegate_progs;
 902                         enum_t = info.prog_t;
 903                         enum_pfx = "BPF_PROG_TYPE_";
 904                         break;
 905                 case OPT_DELEGATE_ATTACHS:
 906                         delegate_msk = &opts->delegate_attachs;
 907                         enum_t = info.attach_t;
 908                         enum_pfx = "BPF_";
 909                         break;
 910                 default:
 911                         return -EINVAL;
 912                 }
 913
 914                 str = param->string;
 915                 while ((p = strsep(&str, ":"))) {
 916                         if (strcmp(p, "any") == 0) {
 917                                 msk |= ~0ULL;
 918                         } else if (find_btf_enum_const(info.btf, enum_t, enum_pfx, p, &val)) {
 919                                 msk |= 1ULL << val;
 920                         } else {
 921                                 err = kstrtou64(p, 0, &msk);
 922                                 if (err)
 923                                         return err;
 924                         }
 925                 }
 926
 927                 /* Setting delegation mount options requires privileges */
 928                 if (msk && !capable(CAP_SYS_ADMIN))
 929                         return -EPERM;
 930
 931                 *delegate_msk |= msk;
 932                 break;
 933         }
 934         default:
 935                 /* ignore unknown mount options */
 936                 break;
 937         }
 938
 939         return 0;
 940 bad_value:
 941         return invalfc(fc, "Bad value for '%s'", param->key);
 942 }
 943
 944 struct bpf_preload_ops *bpf_preload_ops;
 945 EXPORT_SYMBOL_GPL(bpf_preload_ops);
 946
 947 static bool bpf_preload_mod_get(void)
 948 {
 949         /* If bpf_preload.ko wasn't loaded earlier then load it now.
 950          * When bpf_preload is built into vmlinux the module's __init
 951          * function will populate it.
 952          */
 953         if (!bpf_preload_ops) {
 954                 request_module("bpf_preload");
 955                 if (!bpf_preload_ops)
 956                         return false;
 957         }
 958         /* And grab the reference, so the module doesn't disappear while the
 959          * kernel is interacting with the kernel module and its UMD.
 960          */
 961         if (!try_module_get(bpf_preload_ops->owner)) {
 962                 pr_err("bpf_preload module get failed.\n");
 963                 return false;
 964         }
 965         return true;
 966 }
 967
 968 static void bpf_preload_mod_put(void)
 969 {
 970         if (bpf_preload_ops)
 971                 /* now user can "rmmod bpf_preload" if necessary */
 972                 module_put(bpf_preload_ops->owner);
 973 }
 974
 975 static DEFINE_MUTEX(bpf_preload_lock);
 976
 977 static int populate_bpffs(struct dentry *parent)
 978 {
 979         struct bpf_preload_info objs[BPF_PRELOAD_LINKS] = {};
 980         int err = 0, i;
 981
 982         /* grab the mutex to make sure the kernel interactions with bpf_preload
 983          * are serialized
 984          */
 985         mutex_lock(&bpf_preload_lock);
 986
 987         /* if bpf_preload.ko wasn't built into vmlinux then load it */
 988         if (!bpf_preload_mod_get())
 989                 goto out;
 990
 991         err = bpf_preload_ops->preload(objs);
 992         if (err)
 993                 goto out_put;
 994         for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
 995                 bpf_link_inc(objs[i].link);
 996                 err = bpf_iter_link_pin_kernel(parent,
 997                                                objs[i].link_name, objs[i].link);
 998                 if (err) {
 999                         bpf_link_put(objs[i].link);
1000                         goto out_put;
1001                 }
1002         }
1003 out_put:
1004         bpf_preload_mod_put();
1005 out:
1006         mutex_unlock(&bpf_preload_lock);
1007         return err;
1008 }
1009
1010 static int bpf_fill_super(struct super_block *sb, struct fs_context *fc)
1011 {
1012         static const struct tree_descr bpf_rfiles[] = { { "" } };
1013         struct bpf_mount_opts *opts = sb->s_fs_info;
1014         struct inode *inode;
1015         int ret;
1016
1017         /* Mounting an instance of BPF FS requires privileges */
1018         if (fc->user_ns != &init_user_ns && !capable(CAP_SYS_ADMIN))
1019                 return -EPERM;
1020
1021         ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles);
1022         if (ret)
1023                 return ret;
1024
1025         sb->s_op = &bpf_super_ops;
1026
1027         inode = sb->s_root->d_inode;
1028         inode->i_uid = opts->uid;
1029         inode->i_gid = opts->gid;
1030         inode->i_op = &bpf_dir_iops;
1031         inode->i_mode &= ~S_IALLUGO;
1032         populate_bpffs(sb->s_root);
1033         inode->i_mode |= S_ISVTX | opts->mode;
1034         return 0;
1035 }
1036
1037 static int bpf_get_tree(struct fs_context *fc)
1038 {
1039         return get_tree_nodev(fc, bpf_fill_super);
1040 }
1041
1042 static void bpf_free_fc(struct fs_context *fc)
1043 {
1044         kfree(fc->s_fs_info);
1045 }
1046
1047 static const struct fs_context_operations bpf_context_ops = {
1048         .free           = bpf_free_fc,
1049         .parse_param    = bpf_parse_param,
1050         .get_tree       = bpf_get_tree,
1051 };
1052
1053 /*
1054  * Set up the filesystem mount context.
1055  */
1056 static int bpf_init_fs_context(struct fs_context *fc)
1057 {
1058         struct bpf_mount_opts *opts;
1059
1060         opts = kzalloc(sizeof(struct bpf_mount_opts), GFP_KERNEL);
1061         if (!opts)
1062                 return -ENOMEM;
1063
1064         opts->mode = S_IRWXUGO;
1065         opts->uid = current_fsuid();
1066         opts->gid = current_fsgid();
1067
1068         /* start out with no BPF token delegation enabled */
1069         opts->delegate_cmds = 0;
1070         opts->delegate_maps = 0;
1071         opts->delegate_progs = 0;
1072         opts->delegate_attachs = 0;
1073
1074         fc->s_fs_info = opts;
1075         fc->ops = &bpf_context_ops;
1076         return 0;
1077 }
1078
1079 static void bpf_kill_super(struct super_block *sb)
1080 {
1081         struct bpf_mount_opts *opts = sb->s_fs_info;
1082
1083         kill_litter_super(sb);
1084         kfree(opts);
1085 }
1086
1087 static struct file_system_type bpf_fs_type = {
1088         .owner          = THIS_MODULE,
1089         .name           = "bpf",
1090         .init_fs_context = bpf_init_fs_context,
1091         .parameters     = bpf_fs_parameters,
1092         .kill_sb        = bpf_kill_super,
1093         .fs_flags       = FS_USERNS_MOUNT,
1094 };
1095
1096 static int __init bpf_init(void)
1097 {
1098         int ret;
1099
1100         ret = sysfs_create_mount_point(fs_kobj, "bpf");
1101         if (ret)
1102                 return ret;
1103
1104         ret = register_filesystem(&bpf_fs_type);
1105         if (ret)
1106                 sysfs_remove_mount_point(fs_kobj, "bpf");
1107
1108         return ret;
1109 }
1110 fs_initcall(bpf_init);