xref: /openbmc/linux/kernel/bpf/arraymap.c (revision d623f60d)
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 
27 static 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 
37 static 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 */
57 static int 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 
78 static 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 */
152 static 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() */
164 static 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 */
194 static 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 
205 int 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 */
232 static 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 */
251 static 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 
279 int 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 */
318 static 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 */
324 static 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 
341 static 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 
361 static int array_map_check_btf(const struct bpf_map *map, const struct btf *btf,
362 			       u32 btf_key_id, u32 btf_value_id)
363 {
364 	const struct btf_type *key_type, *value_type;
365 	u32 key_size, value_size;
366 	u32 int_data;
367 
368 	key_type = btf_type_id_size(btf, &btf_key_id, &key_size);
369 	if (!key_type || BTF_INFO_KIND(key_type->info) != BTF_KIND_INT)
370 		return -EINVAL;
371 
372 	int_data = *(u32 *)(key_type + 1);
373 	/* bpf array can only take a u32 key.  This check makes
374 	 * sure that the btf matches the attr used during map_create.
375 	 */
376 	if (BTF_INT_BITS(int_data) != 32 || key_size != 4 ||
377 	    BTF_INT_OFFSET(int_data))
378 		return -EINVAL;
379 
380 	value_type = btf_type_id_size(btf, &btf_value_id, &value_size);
381 	if (!value_type || value_size > map->value_size)
382 		return -EINVAL;
383 
384 	return 0;
385 }
386 
387 const struct bpf_map_ops array_map_ops = {
388 	.map_alloc_check = array_map_alloc_check,
389 	.map_alloc = array_map_alloc,
390 	.map_free = array_map_free,
391 	.map_get_next_key = array_map_get_next_key,
392 	.map_lookup_elem = array_map_lookup_elem,
393 	.map_update_elem = array_map_update_elem,
394 	.map_delete_elem = array_map_delete_elem,
395 	.map_gen_lookup = array_map_gen_lookup,
396 	.map_seq_show_elem = array_map_seq_show_elem,
397 	.map_check_btf = array_map_check_btf,
398 };
399 
400 const struct bpf_map_ops percpu_array_map_ops = {
401 	.map_alloc_check = array_map_alloc_check,
402 	.map_alloc = array_map_alloc,
403 	.map_free = array_map_free,
404 	.map_get_next_key = array_map_get_next_key,
405 	.map_lookup_elem = percpu_array_map_lookup_elem,
406 	.map_update_elem = array_map_update_elem,
407 	.map_delete_elem = array_map_delete_elem,
408 };
409 
410 static int fd_array_map_alloc_check(union bpf_attr *attr)
411 {
412 	/* only file descriptors can be stored in this type of map */
413 	if (attr->value_size != sizeof(u32))
414 		return -EINVAL;
415 	return array_map_alloc_check(attr);
416 }
417 
418 static void fd_array_map_free(struct bpf_map *map)
419 {
420 	struct bpf_array *array = container_of(map, struct bpf_array, map);
421 	int i;
422 
423 	synchronize_rcu();
424 
425 	/* make sure it's empty */
426 	for (i = 0; i < array->map.max_entries; i++)
427 		BUG_ON(array->ptrs[i] != NULL);
428 
429 	bpf_map_area_free(array);
430 }
431 
432 static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
433 {
434 	return NULL;
435 }
436 
437 /* only called from syscall */
438 int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value)
439 {
440 	void **elem, *ptr;
441 	int ret =  0;
442 
443 	if (!map->ops->map_fd_sys_lookup_elem)
444 		return -ENOTSUPP;
445 
446 	rcu_read_lock();
447 	elem = array_map_lookup_elem(map, key);
448 	if (elem && (ptr = READ_ONCE(*elem)))
449 		*value = map->ops->map_fd_sys_lookup_elem(ptr);
450 	else
451 		ret = -ENOENT;
452 	rcu_read_unlock();
453 
454 	return ret;
455 }
456 
457 /* only called from syscall */
458 int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
459 				 void *key, void *value, u64 map_flags)
460 {
461 	struct bpf_array *array = container_of(map, struct bpf_array, map);
462 	void *new_ptr, *old_ptr;
463 	u32 index = *(u32 *)key, ufd;
464 
465 	if (map_flags != BPF_ANY)
466 		return -EINVAL;
467 
468 	if (index >= array->map.max_entries)
469 		return -E2BIG;
470 
471 	ufd = *(u32 *)value;
472 	new_ptr = map->ops->map_fd_get_ptr(map, map_file, ufd);
473 	if (IS_ERR(new_ptr))
474 		return PTR_ERR(new_ptr);
475 
476 	old_ptr = xchg(array->ptrs + index, new_ptr);
477 	if (old_ptr)
478 		map->ops->map_fd_put_ptr(old_ptr);
479 
480 	return 0;
481 }
482 
483 static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
484 {
485 	struct bpf_array *array = container_of(map, struct bpf_array, map);
486 	void *old_ptr;
487 	u32 index = *(u32 *)key;
488 
489 	if (index >= array->map.max_entries)
490 		return -E2BIG;
491 
492 	old_ptr = xchg(array->ptrs + index, NULL);
493 	if (old_ptr) {
494 		map->ops->map_fd_put_ptr(old_ptr);
495 		return 0;
496 	} else {
497 		return -ENOENT;
498 	}
499 }
500 
501 static void *prog_fd_array_get_ptr(struct bpf_map *map,
502 				   struct file *map_file, int fd)
503 {
504 	struct bpf_array *array = container_of(map, struct bpf_array, map);
505 	struct bpf_prog *prog = bpf_prog_get(fd);
506 
507 	if (IS_ERR(prog))
508 		return prog;
509 
510 	if (!bpf_prog_array_compatible(array, prog)) {
511 		bpf_prog_put(prog);
512 		return ERR_PTR(-EINVAL);
513 	}
514 
515 	return prog;
516 }
517 
518 static void prog_fd_array_put_ptr(void *ptr)
519 {
520 	bpf_prog_put(ptr);
521 }
522 
523 static u32 prog_fd_array_sys_lookup_elem(void *ptr)
524 {
525 	return ((struct bpf_prog *)ptr)->aux->id;
526 }
527 
528 /* decrement refcnt of all bpf_progs that are stored in this map */
529 static void bpf_fd_array_map_clear(struct bpf_map *map)
530 {
531 	struct bpf_array *array = container_of(map, struct bpf_array, map);
532 	int i;
533 
534 	for (i = 0; i < array->map.max_entries; i++)
535 		fd_array_map_delete_elem(map, &i);
536 }
537 
538 const struct bpf_map_ops prog_array_map_ops = {
539 	.map_alloc_check = fd_array_map_alloc_check,
540 	.map_alloc = array_map_alloc,
541 	.map_free = fd_array_map_free,
542 	.map_get_next_key = array_map_get_next_key,
543 	.map_lookup_elem = fd_array_map_lookup_elem,
544 	.map_delete_elem = fd_array_map_delete_elem,
545 	.map_fd_get_ptr = prog_fd_array_get_ptr,
546 	.map_fd_put_ptr = prog_fd_array_put_ptr,
547 	.map_fd_sys_lookup_elem = prog_fd_array_sys_lookup_elem,
548 	.map_release_uref = bpf_fd_array_map_clear,
549 };
550 
551 static struct bpf_event_entry *bpf_event_entry_gen(struct file *perf_file,
552 						   struct file *map_file)
553 {
554 	struct bpf_event_entry *ee;
555 
556 	ee = kzalloc(sizeof(*ee), GFP_ATOMIC);
557 	if (ee) {
558 		ee->event = perf_file->private_data;
559 		ee->perf_file = perf_file;
560 		ee->map_file = map_file;
561 	}
562 
563 	return ee;
564 }
565 
566 static void __bpf_event_entry_free(struct rcu_head *rcu)
567 {
568 	struct bpf_event_entry *ee;
569 
570 	ee = container_of(rcu, struct bpf_event_entry, rcu);
571 	fput(ee->perf_file);
572 	kfree(ee);
573 }
574 
575 static void bpf_event_entry_free_rcu(struct bpf_event_entry *ee)
576 {
577 	call_rcu(&ee->rcu, __bpf_event_entry_free);
578 }
579 
580 static void *perf_event_fd_array_get_ptr(struct bpf_map *map,
581 					 struct file *map_file, int fd)
582 {
583 	struct bpf_event_entry *ee;
584 	struct perf_event *event;
585 	struct file *perf_file;
586 	u64 value;
587 
588 	perf_file = perf_event_get(fd);
589 	if (IS_ERR(perf_file))
590 		return perf_file;
591 
592 	ee = ERR_PTR(-EOPNOTSUPP);
593 	event = perf_file->private_data;
594 	if (perf_event_read_local(event, &value, NULL, NULL) == -EOPNOTSUPP)
595 		goto err_out;
596 
597 	ee = bpf_event_entry_gen(perf_file, map_file);
598 	if (ee)
599 		return ee;
600 	ee = ERR_PTR(-ENOMEM);
601 err_out:
602 	fput(perf_file);
603 	return ee;
604 }
605 
606 static void perf_event_fd_array_put_ptr(void *ptr)
607 {
608 	bpf_event_entry_free_rcu(ptr);
609 }
610 
611 static void perf_event_fd_array_release(struct bpf_map *map,
612 					struct file *map_file)
613 {
614 	struct bpf_array *array = container_of(map, struct bpf_array, map);
615 	struct bpf_event_entry *ee;
616 	int i;
617 
618 	rcu_read_lock();
619 	for (i = 0; i < array->map.max_entries; i++) {
620 		ee = READ_ONCE(array->ptrs[i]);
621 		if (ee && ee->map_file == map_file)
622 			fd_array_map_delete_elem(map, &i);
623 	}
624 	rcu_read_unlock();
625 }
626 
627 const struct bpf_map_ops perf_event_array_map_ops = {
628 	.map_alloc_check = fd_array_map_alloc_check,
629 	.map_alloc = array_map_alloc,
630 	.map_free = fd_array_map_free,
631 	.map_get_next_key = array_map_get_next_key,
632 	.map_lookup_elem = fd_array_map_lookup_elem,
633 	.map_delete_elem = fd_array_map_delete_elem,
634 	.map_fd_get_ptr = perf_event_fd_array_get_ptr,
635 	.map_fd_put_ptr = perf_event_fd_array_put_ptr,
636 	.map_release = perf_event_fd_array_release,
637 };
638 
639 #ifdef CONFIG_CGROUPS
640 static void *cgroup_fd_array_get_ptr(struct bpf_map *map,
641 				     struct file *map_file /* not used */,
642 				     int fd)
643 {
644 	return cgroup_get_from_fd(fd);
645 }
646 
647 static void cgroup_fd_array_put_ptr(void *ptr)
648 {
649 	/* cgroup_put free cgrp after a rcu grace period */
650 	cgroup_put(ptr);
651 }
652 
653 static void cgroup_fd_array_free(struct bpf_map *map)
654 {
655 	bpf_fd_array_map_clear(map);
656 	fd_array_map_free(map);
657 }
658 
659 const struct bpf_map_ops cgroup_array_map_ops = {
660 	.map_alloc_check = fd_array_map_alloc_check,
661 	.map_alloc = array_map_alloc,
662 	.map_free = cgroup_fd_array_free,
663 	.map_get_next_key = array_map_get_next_key,
664 	.map_lookup_elem = fd_array_map_lookup_elem,
665 	.map_delete_elem = fd_array_map_delete_elem,
666 	.map_fd_get_ptr = cgroup_fd_array_get_ptr,
667 	.map_fd_put_ptr = cgroup_fd_array_put_ptr,
668 };
669 #endif
670 
671 static struct bpf_map *array_of_map_alloc(union bpf_attr *attr)
672 {
673 	struct bpf_map *map, *inner_map_meta;
674 
675 	inner_map_meta = bpf_map_meta_alloc(attr->inner_map_fd);
676 	if (IS_ERR(inner_map_meta))
677 		return inner_map_meta;
678 
679 	map = array_map_alloc(attr);
680 	if (IS_ERR(map)) {
681 		bpf_map_meta_free(inner_map_meta);
682 		return map;
683 	}
684 
685 	map->inner_map_meta = inner_map_meta;
686 
687 	return map;
688 }
689 
690 static void array_of_map_free(struct bpf_map *map)
691 {
692 	/* map->inner_map_meta is only accessed by syscall which
693 	 * is protected by fdget/fdput.
694 	 */
695 	bpf_map_meta_free(map->inner_map_meta);
696 	bpf_fd_array_map_clear(map);
697 	fd_array_map_free(map);
698 }
699 
700 static void *array_of_map_lookup_elem(struct bpf_map *map, void *key)
701 {
702 	struct bpf_map **inner_map = array_map_lookup_elem(map, key);
703 
704 	if (!inner_map)
705 		return NULL;
706 
707 	return READ_ONCE(*inner_map);
708 }
709 
710 static u32 array_of_map_gen_lookup(struct bpf_map *map,
711 				   struct bpf_insn *insn_buf)
712 {
713 	struct bpf_array *array = container_of(map, struct bpf_array, map);
714 	u32 elem_size = round_up(map->value_size, 8);
715 	struct bpf_insn *insn = insn_buf;
716 	const int ret = BPF_REG_0;
717 	const int map_ptr = BPF_REG_1;
718 	const int index = BPF_REG_2;
719 
720 	*insn++ = BPF_ALU64_IMM(BPF_ADD, map_ptr, offsetof(struct bpf_array, value));
721 	*insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0);
722 	if (map->unpriv_array) {
723 		*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 6);
724 		*insn++ = BPF_ALU32_IMM(BPF_AND, ret, array->index_mask);
725 	} else {
726 		*insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5);
727 	}
728 	if (is_power_of_2(elem_size))
729 		*insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(elem_size));
730 	else
731 		*insn++ = BPF_ALU64_IMM(BPF_MUL, ret, elem_size);
732 	*insn++ = BPF_ALU64_REG(BPF_ADD, ret, map_ptr);
733 	*insn++ = BPF_LDX_MEM(BPF_DW, ret, ret, 0);
734 	*insn++ = BPF_JMP_IMM(BPF_JEQ, ret, 0, 1);
735 	*insn++ = BPF_JMP_IMM(BPF_JA, 0, 0, 1);
736 	*insn++ = BPF_MOV64_IMM(ret, 0);
737 
738 	return insn - insn_buf;
739 }
740 
741 const struct bpf_map_ops array_of_maps_map_ops = {
742 	.map_alloc_check = fd_array_map_alloc_check,
743 	.map_alloc = array_of_map_alloc,
744 	.map_free = array_of_map_free,
745 	.map_get_next_key = array_map_get_next_key,
746 	.map_lookup_elem = array_of_map_lookup_elem,
747 	.map_delete_elem = fd_array_map_delete_elem,
748 	.map_fd_get_ptr = bpf_map_fd_get_ptr,
749 	.map_fd_put_ptr = bpf_map_fd_put_ptr,
750 	.map_fd_sys_lookup_elem = bpf_map_fd_sys_lookup_elem,
751 	.map_gen_lookup = array_of_map_gen_lookup,
752 };
753