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