projects/linux·blob v5.0-rc5 · refs

798 lines · 20.6 KiB

1/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 * Copyright (c) 2016,2017 Facebook
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of version 2 of the GNU General Public
6 * License as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 */
13#include <linux/bpf.h>
14#include <linux/btf.h>
15#include <linux/err.h>
16#include <linux/slab.h>
17#include <linux/mm.h>
18#include <linux/filter.h>
19#include <linux/perf_event.h>
20#include <uapi/linux/btf.h>
21
22#include "map_in_map.h"
23
24#define ARRAY_CREATE_FLAG_MASK \
25 (BPF_F_NUMA_NODE | BPF_F_RDONLY | BPF_F_WRONLY)
26
27static void bpf_array_free_percpu(struct bpf_array *array)
28{
29 int i;
30
31 for (i = 0; i < array->map.max_entries; i++) {
32 free_percpu(array->pptrs[i]);
33 cond_resched();
34 }
35}
36
37static int bpf_array_alloc_percpu(struct bpf_array *array)
38{
39 void __percpu *ptr;
40 int i;
41
42 for (i = 0; i < array->map.max_entries; i++) {
43 ptr = __alloc_percpu_gfp(array->elem_size, 8,
44 GFP_USER | __GFP_NOWARN);
45 if (!ptr) {
46 bpf_array_free_percpu(array);
47 return -ENOMEM;
48 }
49 array->pptrs[i] = ptr;
50 cond_resched();
51 }
52
53 return 0;
54}
55
56/* Called from syscall */
57int array_map_alloc_check(union bpf_attr *attr)
58{
59 bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
60 int numa_node = bpf_map_attr_numa_node(attr);
61
62 /* check sanity of attributes */
63 if (attr->max_entries == 0 || attr->key_size != 4 ||
64 attr->value_size == 0 ||
65 attr->map_flags & ~ARRAY_CREATE_FLAG_MASK ||
66 (percpu && numa_node != NUMA_NO_NODE))
67 return -EINVAL;
68
69 if (attr->value_size > KMALLOC_MAX_SIZE)
70 /* if value_size is bigger, the user space won't be able to
71 * access the elements.
72 */
73 return -E2BIG;
74
75 return 0;
76}
77
78static struct bpf_map *array_map_alloc(union bpf_attr *attr)
79{
80 bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
81 int ret, numa_node = bpf_map_attr_numa_node(attr);
82 u32 elem_size, index_mask, max_entries;
83 bool unpriv = !capable(CAP_SYS_ADMIN);
84 u64 cost, array_size, mask64;
85 struct bpf_array *array;
86
87 elem_size = round_up(attr->value_size, 8);
88
89 max_entries = attr->max_entries;
90
91 /* On 32 bit archs roundup_pow_of_two() with max_entries that has
92 * upper most bit set in u32 space is undefined behavior due to
93 * resulting 1U << 32, so do it manually here in u64 space.
94 */
95 mask64 = fls_long(max_entries - 1);
96 mask64 = 1ULL << mask64;
97 mask64 -= 1;
98
99 index_mask = mask64;
100 if (unpriv) {
101 /* round up array size to nearest power of 2,
102 * since cpu will speculate within index_mask limits
103 */
104 max_entries = index_mask + 1;
105 /* Check for overflows. */
106 if (max_entries < attr->max_entries)
107 return ERR_PTR(-E2BIG);
108 }
109
110 array_size = sizeof(*array);
111 if (percpu)
112 array_size += (u64) max_entries * sizeof(void *);
113 else
114 array_size += (u64) max_entries * elem_size;
115
116 /* make sure there is no u32 overflow later in round_up() */
117 cost = array_size;
118 if (cost >= U32_MAX - PAGE_SIZE)
119 return ERR_PTR(-ENOMEM);
120 if (percpu) {
121 cost += (u64)attr->max_entries * elem_size * num_possible_cpus();
122 if (cost >= U32_MAX - PAGE_SIZE)
123 return ERR_PTR(-ENOMEM);
124 }
125 cost = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
126
127 ret = bpf_map_precharge_memlock(cost);
128 if (ret < 0)
129 return ERR_PTR(ret);
130
131 /* allocate all map elements and zero-initialize them */
132 array = bpf_map_area_alloc(array_size, numa_node);
133 if (!array)
134 return ERR_PTR(-ENOMEM);
135 array->index_mask = index_mask;
136 array->map.unpriv_array = unpriv;
137
138 /* copy mandatory map attributes */
139 bpf_map_init_from_attr(&array->map, attr);
140 array->map.pages = cost;
141 array->elem_size = elem_size;
142
143 if (percpu && bpf_array_alloc_percpu(array)) {
144 bpf_map_area_free(array);
145 return ERR_PTR(-ENOMEM);
146 }
147
148 return &array->map;
149}
150
151/* Called from syscall or from eBPF program */
152static void *array_map_lookup_elem(struct bpf_map *map, void *key)
153{
154 struct bpf_array *array = container_of(map, struct bpf_array, map);
155 u32 index = *(u32 *)key;
156
157 if (unlikely(index >= array->map.max_entries))
158 return NULL;
159
160 return array->value + array->elem_size * (index & array->index_mask);
161}
162
163/* emit BPF instructions equivalent to C code of array_map_lookup_elem() */
164static u32 array_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf)
165{
166 struct bpf_array *array = container_of(map, struct bpf_array, map);
167 struct bpf_insn *insn = insn_buf;
168 u32 elem_size = round_up(map->value_size, 8);
169 const int ret = BPF_REG_0;
170 const int map_ptr = BPF_REG_1;
171 const int index = BPF_REG_2;
172
173 *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
174 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
175 if (map->unpriv_array) {
176 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 4);
177 *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
178 } else {
179 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 3);
180 }
181
182 if (is_power_of_2(elem_size)) {
183 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
184 } else {
185 *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
186 }
187 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
188 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
189 *insn++ = BPF_MOV64_IMM(ret, 0);
190 return insn - insn_buf;
191}
192
193/* Called from eBPF program */
194static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
195{
196 struct bpf_array *array = container_of(map, struct bpf_array, map);
197 u32 index = *(u32 *)key;
198
199 if (unlikely(index >= array->map.max_entries))
200 return NULL;
201
202 return this_cpu_ptr(array->pptrs[index & array->index_mask]);
203}
204
205int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
206{
207 struct bpf_array *array = container_of(map, struct bpf_array, map);
208 u32 index = *(u32 *)key;
209 void __percpu *pptr;
210 int cpu, off = 0;
211 u32 size;
212
213 if (unlikely(index >= array->map.max_entries))
214 return -ENOENT;
215
216 /* per_cpu areas are zero-filled and bpf programs can only
217 * access 'value_size' of them, so copying rounded areas
218 * will not leak any kernel data
219 */
220 size = round_up(map->value_size, 8);
221 rcu_read_lock();
222 pptr = array->pptrs[index & array->index_mask];
223 for_each_possible_cpu(cpu) {
224 bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
225 off += size;
226 }
227 rcu_read_unlock();
228 return 0;
229}
230
231/* Called from syscall */
232static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
233{
234 struct bpf_array *array = container_of(map, struct bpf_array, map);
235 u32 index = key ? *(u32 *)key : U32_MAX;
236 u32 *next = (u32 *)next_key;
237
238 if (index >= array->map.max_entries) {
239 *next = 0;
240 return 0;
241 }
242
243 if (index == array->map.max_entries - 1)
244 return -ENOENT;
245
246 *next = index + 1;
247 return 0;
248}
249
250/* Called from syscall or from eBPF program */
251static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
252 u64 map_flags)
253{
254 struct bpf_array *array = container_of(map, struct bpf_array, map);
255 u32 index = *(u32 *)key;
256
257 if (unlikely(map_flags > BPF_EXIST))
258 /* unknown flags */
259 return -EINVAL;
260
261 if (unlikely(index >= array->map.max_entries))
262 /* all elements were pre-allocated, cannot insert a new one */
263 return -E2BIG;
264
265 if (unlikely(map_flags == BPF_NOEXIST))
266 /* all elements already exist */
267 return -EEXIST;
268
269 if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
270 memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
271 value, map->value_size);
272 else
273 memcpy(array->value +
274 array->elem_size * (index & array->index_mask),
275 value, map->value_size);
276 return 0;
277}
278
279int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
280 u64 map_flags)
281{
282 struct bpf_array *array = container_of(map, struct bpf_array, map);
283 u32 index = *(u32 *)key;
284 void __percpu *pptr;
285 int cpu, off = 0;
286 u32 size;
287
288 if (unlikely(map_flags > BPF_EXIST))
289 /* unknown flags */
290 return -EINVAL;
291
292 if (unlikely(index >= array->map.max_entries))
293 /* all elements were pre-allocated, cannot insert a new one */
294 return -E2BIG;
295
296 if (unlikely(map_flags == BPF_NOEXIST))
297 /* all elements already exist */
298 return -EEXIST;
299
300 /* the user space will provide round_up(value_size, 8) bytes that
301 * will be copied into per-cpu area. bpf programs can only access
302 * value_size of it. During lookup the same extra bytes will be
303 * returned or zeros which were zero-filled by percpu_alloc,
304 * so no kernel data leaks possible
305 */
306 size = round_up(map->value_size, 8);
307 rcu_read_lock();
308 pptr = array->pptrs[index & array->index_mask];
309 for_each_possible_cpu(cpu) {
310 bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
311 off += size;
312 }
313 rcu_read_unlock();
314 return 0;
315}
316
317/* Called from syscall or from eBPF program */
318static int array_map_delete_elem(struct bpf_map *map, void *key)
319{
320 return -EINVAL;
321}
322
323/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
324static void array_map_free(struct bpf_map *map)
325{
326 struct bpf_array *array = container_of(map, struct bpf_array, map);
327
328 /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
329 * so the programs (can be more than one that used this map) were
330 * disconnected from events. Wait for outstanding programs to complete
331 * and free the array
332 */
333 synchronize_rcu();
334
335 if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
336 bpf_array_free_percpu(array);
337
338 bpf_map_area_free(array);
339}
340
341static void array_map_seq_show_elem(struct bpf_map *map, void *key,
342 struct seq_file *m)
343{
344 void *value;
345
346 rcu_read_lock();
347
348 value = array_map_lookup_elem(map, key);
349 if (!value) {
350 rcu_read_unlock();
351 return;
352 }
353
354 seq_printf(m, "%u: ", *(u32 *)key);
355 btf_type_seq_show(map->btf, map->btf_value_type_id, value, m);
356 seq_puts(m, "\n");
357
358 rcu_read_unlock();
359}
360
361static void percpu_array_map_seq_show_elem(struct bpf_map *map, void *key,
362 struct seq_file *m)
363{
364 struct bpf_array *array = container_of(map, struct bpf_array, map);
365 u32 index = *(u32 *)key;
366 void __percpu *pptr;
367 int cpu;
368
369 rcu_read_lock();
370
371 seq_printf(m, "%u: {\n", *(u32 *)key);
372 pptr = array->pptrs[index & array->index_mask];
373 for_each_possible_cpu(cpu) {
374 seq_printf(m, "\tcpu%d: ", cpu);
375 btf_type_seq_show(map->btf, map->btf_value_type_id,
376 per_cpu_ptr(pptr, cpu), m);
377 seq_puts(m, "\n");
378 }
379 seq_puts(m, "}\n");
380
381 rcu_read_unlock();
382}
383
384static int array_map_check_btf(const struct bpf_map *map,
385 const struct btf *btf,
386 const struct btf_type *key_type,
387 const struct btf_type *value_type)
388{
389 u32 int_data;
390
391 if (BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
392 return -EINVAL;
393
394 int_data = *(u32 *)(key_type + 1);
395 /* bpf array can only take a u32 key. This check makes sure
396 * that the btf matches the attr used during map_create.
397 */
398 if (BTF_INT_BITS(int_data) != 32 || BTF_INT_OFFSET(int_data))
399 return -EINVAL;
400
401 return 0;
402}
403
404const struct bpf_map_ops array_map_ops = {
405 .map_alloc_check = array_map_alloc_check,
406 .map_alloc = array_map_alloc,
407 .map_free = array_map_free,
408 .map_get_next_key = array_map_get_next_key,
409 .map_lookup_elem = array_map_lookup_elem,
410 .map_update_elem = array_map_update_elem,
411 .map_delete_elem = array_map_delete_elem,
412 .map_gen_lookup = array_map_gen_lookup,
413 .map_seq_show_elem = array_map_seq_show_elem,
414 .map_check_btf = array_map_check_btf,
415};
416
417const struct bpf_map_ops percpu_array_map_ops = {
418 .map_alloc_check = array_map_alloc_check,
419 .map_alloc = array_map_alloc,
420 .map_free = array_map_free,
421 .map_get_next_key = array_map_get_next_key,
422 .map_lookup_elem = percpu_array_map_lookup_elem,
423 .map_update_elem = array_map_update_elem,
424 .map_delete_elem = array_map_delete_elem,
425 .map_seq_show_elem = percpu_array_map_seq_show_elem,
426 .map_check_btf = array_map_check_btf,
427};
428
429static int fd_array_map_alloc_check(union bpf_attr *attr)
430{
431 /* only file descriptors can be stored in this type of map */
432 if (attr->value_size != sizeof(u32))
433 return -EINVAL;
434 return array_map_alloc_check(attr);
435}
436
437static void fd_array_map_free(struct bpf_map *map)
438{
439 struct bpf_array *array = container_of(map, struct bpf_array, map);
440 int i;
441
442 synchronize_rcu();
443
444 /* make sure it's empty */
445 for (i = 0; i < array->map.max_entries; i++)
446 BUG_ON(array->ptrs[i] != NULL);
447
448 bpf_map_area_free(array);
449}
450
451static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
452{
453 return ERR_PTR(-EOPNOTSUPP);
454}
455
456/* only called from syscall */
457int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
458{
459 void **elem, *ptr;
460 int ret = 0;
461
462 if (!map->ops->map_fd_sys_lookup_elem)
463 return -ENOTSUPP;
464
465 rcu_read_lock();
466 elem = array_map_lookup_elem(map, key);
467 if (elem && (ptr = READ_ONCE(*elem)))
468 *value = map->ops->map_fd_sys_lookup_elem(ptr);
469 else
470 ret = -ENOENT;
471 rcu_read_unlock();
472
473 return ret;
474}
475
476/* only called from syscall */
477int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
478 void *key, void *value, u64 map_flags)
479{
480 struct bpf_array *array = container_of(map, struct bpf_array, map);
481 void *new_ptr, *old_ptr;
482 u32 index = *(u32 *)key, ufd;
483
484 if (map_flags != BPF_ANY)
485 return -EINVAL;
486
487 if (index >= array->map.max_entries)
488 return -E2BIG;
489
490 ufd = *(u32 *)value;
491 new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
492 if (IS_ERR(new_ptr))
493 return PTR_ERR(new_ptr);
494
495 old_ptr = xchg(array->ptrs + index, new_ptr);
496 if (old_ptr)
497 map->ops->map_fd_put_ptr(old_ptr);
498
499 return 0;
500}
501
502static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
503{
504 struct bpf_array *array = container_of(map, struct bpf_array, map);
505 void *old_ptr;
506 u32 index = *(u32 *)key;
507
508 if (index >= array->map.max_entries)
509 return -E2BIG;
510
511 old_ptr = xchg(array->ptrs + index, NULL);
512 if (old_ptr) {
513 map->ops->map_fd_put_ptr(old_ptr);
514 return 0;
515 } else {
516 return -ENOENT;
517 }
518}
519
520static void *prog_fd_array_get_ptr(struct bpf_map *map,
521 struct file *map_file, int fd)
522{
523 struct bpf_array *array = container_of(map, struct bpf_array, map);
524 struct bpf_prog *prog = bpf_prog_get(fd);
525
526 if (IS_ERR(prog))
527 return prog;
528
529 if (!bpf_prog_array_compatible(array, prog)) {
530 bpf_prog_put(prog);
531 return ERR_PTR(-EINVAL);
532 }
533
534 return prog;
535}
536
537static void prog_fd_array_put_ptr(void *ptr)
538{
539 bpf_prog_put(ptr);
540}
541
542static u32 prog_fd_array_sys_lookup_elem(void *ptr)
543{
544 return ((struct bpf_prog *)ptr)->aux->id;
545}
546
547/* decrement refcnt of all bpf_progs that are stored in this map */
548static void bpf_fd_array_map_clear(struct bpf_map *map)
549{
550 struct bpf_array *array = container_of(map, struct bpf_array, map);
551 int i;
552
553 for (i = 0; i < array->map.max_entries; i++)
554 fd_array_map_delete_elem(map, &i);
555}
556
557static void prog_array_map_seq_show_elem(struct bpf_map *map, void *key,
558 struct seq_file *m)
559{
560 void **elem, *ptr;
561 u32 prog_id;
562
563 rcu_read_lock();
564
565 elem = array_map_lookup_elem(map, key);
566 if (elem) {
567 ptr = READ_ONCE(*elem);
568 if (ptr) {
569 seq_printf(m, "%u: ", *(u32 *)key);
570 prog_id = prog_fd_array_sys_lookup_elem(ptr);
571 btf_type_seq_show(map->btf, map->btf_value_type_id,
572 &prog_id, m);
573 seq_puts(m, "\n");
574 }
575 }
576
577 rcu_read_unlock();
578}
579
580const struct bpf_map_ops prog_array_map_ops = {
581 .map_alloc_check = fd_array_map_alloc_check,
582 .map_alloc = array_map_alloc,
583 .map_free = fd_array_map_free,
584 .map_get_next_key = array_map_get_next_key,
585 .map_lookup_elem = fd_array_map_lookup_elem,
586 .map_delete_elem = fd_array_map_delete_elem,
587 .map_fd_get_ptr = prog_fd_array_get_ptr,
588 .map_fd_put_ptr = prog_fd_array_put_ptr,
589 .map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem,
590 .map_release_uref = bpf_fd_array_map_clear,
591 .map_seq_show_elem = prog_array_map_seq_show_elem,
592};
593
594static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
595 struct file *map_file)
596{
597 struct bpf_event_entry *ee;
598
599 ee = kzalloc(sizeof(*ee), GFP_ATOMIC);
600 if (ee) {
601 ee->event = perf_file->private_data;
602 ee->perf_file = perf_file;
603 ee->map_file = map_file;
604 }
605
606 return ee;
607}
608
609static void __bpf_event_entry_free(struct rcu_head *rcu)
610{
611 struct bpf_event_entry *ee;
612
613 ee = container_of(rcu, struct bpf_event_entry, rcu);
614 fput(ee->perf_file);
615 kfree(ee);
616}
617
618static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
619{
620 call_rcu(&ee->rcu, __bpf_event_entry_free);
621}
622
623static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
624 struct file *map_file, int fd)
625{
626 struct bpf_event_entry *ee;
627 struct perf_event *event;
628 struct file *perf_file;
629 u64 value;
630
631 perf_file = perf_event_get(fd);
632 if (IS_ERR(perf_file))
633 return perf_file;
634
635 ee = ERR_PTR(-EOPNOTSUPP);
636 event = perf_file->private_data;
637 if (perf_event_read_local(event, &value, NULL, NULL) == -EOPNOTSUPP)
638 goto err_out;
639
640 ee = bpf_event_entry_gen(perf_file, map_file);
641 if (ee)
642 return ee;
643 ee = ERR_PTR(-ENOMEM);
644err_out:
645 fput(perf_file);
646 return ee;
647}
648
649static void perf_event_fd_array_put_ptr(void *ptr)
650{
651 bpf_event_entry_free_rcu(ptr);
652}
653
654static void perf_event_fd_array_release(struct bpf_map *map,
655 struct file *map_file)
656{
657 struct bpf_array *array = container_of(map, struct bpf_array, map);
658 struct bpf_event_entry *ee;
659 int i;
660
661 rcu_read_lock();
662 for (i = 0; i < array->map.max_entries; i++) {
663 ee = READ_ONCE(array->ptrs[i]);
664 if (ee && ee->map_file == map_file)
665 fd_array_map_delete_elem(map, &i);
666 }
667 rcu_read_unlock();
668}
669
670const struct bpf_map_ops perf_event_array_map_ops = {
671 .map_alloc_check = fd_array_map_alloc_check,
672 .map_alloc = array_map_alloc,
673 .map_free = fd_array_map_free,
674 .map_get_next_key = array_map_get_next_key,
675 .map_lookup_elem = fd_array_map_lookup_elem,
676 .map_delete_elem = fd_array_map_delete_elem,
677 .map_fd_get_ptr = perf_event_fd_array_get_ptr,
678 .map_fd_put_ptr = perf_event_fd_array_put_ptr,
679 .map_release = perf_event_fd_array_release,
680 .map_check_btf = map_check_no_btf,
681};
682
683#ifdef CONFIG_CGROUPS
684static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
685 struct file *map_file /* not used */,
686 int fd)
687{
688 return cgroup_get_from_fd(fd);
689}
690
691static void cgroup_fd_array_put_ptr(void *ptr)
692{
693 /* cgroup_put free cgrp after a rcu grace period */
694 cgroup_put(ptr);
695}
696
697static void cgroup_fd_array_free(struct bpf_map *map)
698{
699 bpf_fd_array_map_clear(map);
700 fd_array_map_free(map);
701}
702
703const struct bpf_map_ops cgroup_array_map_ops = {
704 .map_alloc_check = fd_array_map_alloc_check,
705 .map_alloc = array_map_alloc,
706 .map_free = cgroup_fd_array_free,
707 .map_get_next_key = array_map_get_next_key,
708 .map_lookup_elem = fd_array_map_lookup_elem,
709 .map_delete_elem = fd_array_map_delete_elem,
710 .map_fd_get_ptr = cgroup_fd_array_get_ptr,
711 .map_fd_put_ptr = cgroup_fd_array_put_ptr,
712 .map_check_btf = map_check_no_btf,
713};
714#endif
715
716static struct bpf_map *array_of_map_alloc(union bpf_attr *attr)
717{
718 struct bpf_map *map, *inner_map_meta;
719
720 inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
721 if (IS_ERR(inner_map_meta))
722 return inner_map_meta;
723
724 map = array_map_alloc(attr);
725 if (IS_ERR(map)) {
726 bpf_map_meta_free(inner_map_meta);
727 return map;
728 }
729
730 map->inner_map_meta = inner_map_meta;
731
732 return map;
733}
734
735static void array_of_map_free(struct bpf_map *map)
736{
737 /* map->inner_map_meta is only accessed by syscall which
738 * is protected by fdget/fdput.
739 */
740 bpf_map_meta_free(map->inner_map_meta);
741 bpf_fd_array_map_clear(map);
742 fd_array_map_free(map);
743}
744
745static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
746{
747 struct bpf_map **inner_map = array_map_lookup_elem(map, key);
748
749 if (!inner_map)
750 return NULL;
751
752 return READ_ONCE(*inner_map);
753}
754
755static u32 array_of_map_gen_lookup(struct bpf_map *map,
756 struct bpf_insn *insn_buf)
757{
758 struct bpf_array *array = container_of(map, struct bpf_array, map);
759 u32 elem_size = round_up(map->value_size, 8);
760 struct bpf_insn *insn = insn_buf;
761 const int ret = BPF_REG_0;
762 const int map_ptr = BPF_REG_1;
763 const int index = BPF_REG_2;
764
765 *insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
766 *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
767 if (map->unpriv_array) {
768 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6);
769 *insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
770 } else {
771 *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
772 }
773 if (is_power_of_2(elem_size))
774 *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
775 else
776 *insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
777 *insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
778 *insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
779 *insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
780 *insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
781 *insn++ = BPF_MOV64_IMM(ret, 0);
782
783 return insn - insn_buf;
784}
785
786const struct bpf_map_ops array_of_maps_map_ops = {
787 .map_alloc_check = fd_array_map_alloc_check,
788 .map_alloc = array_of_map_alloc,
789 .map_free = array_of_map_free,
790 .map_get_next_key = array_map_get_next_key,
791 .map_lookup_elem = array_of_map_lookup_elem,
792 .map_delete_elem = fd_array_map_delete_elem,
793 .map_fd_get_ptr = bpf_map_fd_get_ptr,
794 .map_fd_put_ptr = bpf_map_fd_put_ptr,
795 .map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
796 .map_gen_lookup = array_of_map_gen_lookup,
797 .map_check_btf = map_check_no_btf,
798};