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