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_printf(m, "%c", first ? '=' : ':');
713 name += pfx_len;
714 while (*name) {
715 seq_printf(m, "%c", 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;
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 while ((p = strsep(¶m->string, ":"))) {
915 if (strcmp(p, "any") == 0) {
916 msk |= ~0ULL;
917 } else if (find_btf_enum_const(info.btf, enum_t, enum_pfx, p, &val)) {
918 msk |= 1ULL << val;
919 } else {
920 err = kstrtou64(p, 0, &msk);
921 if (err)
922 return err;
923 }
924 }
925
926 /* Setting delegation mount options requires privileges */
927 if (msk && !capable(CAP_SYS_ADMIN))
928 return -EPERM;
929
930 *delegate_msk |= msk;
931 break;
932 }
933 default:
934 /* ignore unknown mount options */
935 break;
936 }
937
938 return 0;
939 bad_value:
940 return invalfc(fc, "Bad value for '%s'", param->key);
941 }
942
943 struct bpf_preload_ops *bpf_preload_ops;
944 EXPORT_SYMBOL_GPL(bpf_preload_ops);
945
946 static bool bpf_preload_mod_get(void)
947 {
948 /* If bpf_preload.ko wasn't loaded earlier then load it now.
949 * When bpf_preload is built into vmlinux the module's __init
950 * function will populate it.
951 */
952 if (!bpf_preload_ops) {
953 request_module("bpf_preload");
954 if (!bpf_preload_ops)
955 return false;
956 }
957 /* And grab the reference, so the module doesn't disappear while the
958 * kernel is interacting with the kernel module and its UMD.
959 */
960 if (!try_module_get(bpf_preload_ops->owner)) {
961 pr_err("bpf_preload module get failed.\n");
962 return false;
963 }
964 return true;
965 }
966
967 static void bpf_preload_mod_put(void)
968 {
969 if (bpf_preload_ops)
970 /* now user can "rmmod bpf_preload" if necessary */
971 module_put(bpf_preload_ops->owner);
972 }
973
974 static DEFINE_MUTEX(bpf_preload_lock);
975
976 static int populate_bpffs(struct dentry *parent)
977 {
978 struct bpf_preload_info objs[BPF_PRELOAD_LINKS] = {};
979 int err = 0, i;
980
981 /* grab the mutex to make sure the kernel interactions with bpf_preload
982 * are serialized
983 */
984 mutex_lock(&bpf_preload_lock);
985
986 /* if bpf_preload.ko wasn't built into vmlinux then load it */
987 if (!bpf_preload_mod_get())
988 goto out;
989
990 err = bpf_preload_ops->preload(objs);
991 if (err)
992 goto out_put;
993 for (i = 0; i < BPF_PRELOAD_LINKS; i++) {
994 bpf_link_inc(objs[i].link);
995 err = bpf_iter_link_pin_kernel(parent,
996 objs[i].link_name, objs[i].link);
997 if (err) {
998 bpf_link_put(objs[i].link);
999 goto out_put;
1000 }
1001 }
1002 out_put:
1003 bpf_preload_mod_put();
1004 out:
1005 mutex_unlock(&bpf_preload_lock);
1006 return err;
1007 }
1008
1009 static int bpf_fill_super(struct super_block *sb, struct fs_context *fc)
1010 {
1011 static const struct tree_descr bpf_rfiles[] = { { "" } };
1012 struct bpf_mount_opts *opts = sb->s_fs_info;
1013 struct inode *inode;
1014 int ret;
1015
1016 /* Mounting an instance of BPF FS requires privileges */
1017 if (fc->user_ns != &init_user_ns && !capable(CAP_SYS_ADMIN))
1018 return -EPERM;
1019
1020 ret = simple_fill_super(sb, BPF_FS_MAGIC, bpf_rfiles);
1021 if (ret)
1022 return ret;
1023
1024 sb->s_op = &bpf_super_ops;
1025
1026 inode = sb->s_root->d_inode;
1027 inode->i_uid = opts->uid;
1028 inode->i_gid = opts->gid;
1029 inode->i_op = &bpf_dir_iops;
1030 inode->i_mode &= ~S_IALLUGO;
1031 populate_bpffs(sb->s_root);
1032 inode->i_mode |= S_ISVTX | opts->mode;
1033 return 0;
1034 }
1035
1036 static int bpf_get_tree(struct fs_context *fc)
1037 {
1038 return get_tree_nodev(fc, bpf_fill_super);
1039 }
1040
1041 static void bpf_free_fc(struct fs_context *fc)
1042 {
1043 kfree(fc->s_fs_info);
1044 }
1045
1046 static const struct fs_context_operations bpf_context_ops = {
1047 .free = bpf_free_fc,
1048 .parse_param = bpf_parse_param,
1049 .get_tree = bpf_get_tree,
1050 };
1051
1052 /*
1053 * Set up the filesystem mount context.
1054 */
1055 static int bpf_init_fs_context(struct fs_context *fc)
1056 {
1057 struct bpf_mount_opts *opts;
1058
1059 opts = kzalloc(sizeof(struct bpf_mount_opts), GFP_KERNEL);
1060 if (!opts)
1061 return -ENOMEM;
1062
1063 opts->mode = S_IRWXUGO;
1064 opts->uid = current_fsuid();
1065 opts->gid = current_fsgid();
1066
1067 /* start out with no BPF token delegation enabled */
1068 opts->delegate_cmds = 0;
1069 opts->delegate_maps = 0;
1070 opts->delegate_progs = 0;
1071 opts->delegate_attachs = 0;
1072
1073 fc->s_fs_info = opts;
1074 fc->ops = &bpf_context_ops;
1075 return 0;
1076 }
1077
1078 static void bpf_kill_super(struct super_block *sb)
1079 {
1080 struct bpf_mount_opts *opts = sb->s_fs_info;
1081
1082 kill_litter_super(sb);
1083 kfree(opts);
1084 }
1085
1086 static struct file_system_type bpf_fs_type = {
1087 .owner = THIS_MODULE,
1088 .name = "bpf",
1089 .init_fs_context = bpf_init_fs_context,
1090 .parameters = bpf_fs_parameters,
1091 .kill_sb = bpf_kill_super,
1092 .fs_flags = FS_USERNS_MOUNT,
1093 };
1094
1095 static int __init bpf_init(void)
1096 {
1097 int ret;
1098
1099 ret = sysfs_create_mount_point(fs_kobj, "bpf");
1100 if (ret)
1101 return ret;
1102
1103 ret = register_filesystem(&bpf_fs_type);
1104 if (ret)
1105 sysfs_remove_mount_point(fs_kobj, "bpf");
1106
1107 return ret;
1108 }
1109 fs_initcall(bpf_init);
1110
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