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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2017 Facebook
*/
#include <linux/slab.h>
#include <linux/bpf.h>
#include <linux/btf.h>
#include "map_in_map.h"
struct bpf_map *bpf_map_meta_alloc(int inner_map_ufd)
{
struct bpf_map *inner_map, *inner_map_meta;
u32 inner_map_meta_size;
struct fd f;
int ret;
f = fdget(inner_map_ufd);
inner_map = __bpf_map_get(f);
if (IS_ERR(inner_map))
return inner_map;
/* Does not support >1 level map-in-map */
if (inner_map->inner_map_meta) {
ret = -EINVAL;
goto put;
}
if (!inner_map->ops->map_meta_equal) {
ret = -ENOTSUPP;
goto put;
}
inner_map_meta_size = sizeof(*inner_map_meta);
/* In some cases verifier needs to access beyond just base map. */
if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops)
inner_map_meta_size = sizeof(struct bpf_array);
inner_map_meta = kzalloc(inner_map_meta_size, GFP_USER);
if (!inner_map_meta) {
ret = -ENOMEM;
goto put;
}
inner_map_meta->map_type = inner_map->map_type;
inner_map_meta->key_size = inner_map->key_size;
inner_map_meta->value_size = inner_map->value_size;
inner_map_meta->map_flags = inner_map->map_flags;
inner_map_meta->max_entries = inner_map->max_entries;
inner_map_meta->record = btf_record_dup(inner_map->record);
if (IS_ERR(inner_map_meta->record)) {
/* btf_record_dup returns NULL or valid pointer in case of
* invalid/empty/valid, but ERR_PTR in case of errors. During
* equality NULL or IS_ERR is equivalent.
*/
ret = PTR_ERR(inner_map_meta->record);
goto free;
}
/* Note: We must use the same BTF, as we also used btf_record_dup above
* which relies on BTF being same for both maps, as some members like
* record->fields.list_head have pointers like value_rec pointing into
* inner_map->btf.
*/
if (inner_map->btf) {
btf_get(inner_map->btf);
inner_map_meta->btf = inner_map->btf;
}
/* Misc members not needed in bpf_map_meta_equal() check. */
inner_map_meta->ops = inner_map->ops;
if (inner_map->ops == &array_map_ops || inner_map->ops == &percpu_array_map_ops) {
struct bpf_array *inner_array_meta =
container_of(inner_map_meta, struct bpf_array, map);
struct bpf_array *inner_array = container_of(inner_map, struct bpf_array, map);
inner_array_meta->index_mask = inner_array->index_mask;
inner_array_meta->elem_size = inner_array->elem_size;
inner_map_meta->bypass_spec_v1 = inner_map->bypass_spec_v1;
}
fdput(f);
return inner_map_meta;
free:
kfree(inner_map_meta);
put:
fdput(f);
return ERR_PTR(ret);
}
void bpf_map_meta_free(struct bpf_map *map_meta)
{
bpf_map_free_record(map_meta);
btf_put(map_meta->btf);
kfree(map_meta);
}
bool bpf_map_meta_equal(const struct bpf_map *meta0,
const struct bpf_map *meta1)
{
/* No need to compare ops because it is covered by map_type */
return meta0->map_type == meta1->map_type &&
meta0->key_size == meta1->key_size &&
meta0->value_size == meta1->value_size &&
meta0->map_flags == meta1->map_flags &&
btf_record_equal(meta0->record, meta1->record);
}
void *bpf_map_fd_get_ptr(struct bpf_map *map,
struct file *map_file /* not used */,
int ufd)
{
struct bpf_map *inner_map, *inner_map_meta;
struct fd f;
f = fdget(ufd);
inner_map = __bpf_map_get(f);
if (IS_ERR(inner_map))
return inner_map;
inner_map_meta = map->inner_map_meta;
if (inner_map_meta->ops->map_meta_equal(inner_map_meta, inner_map))
bpf_map_inc(inner_map);
else
inner_map = ERR_PTR(-EINVAL);
fdput(f);
return inner_map;
}
void bpf_map_fd_put_ptr(struct bpf_map *map, void *ptr, bool need_defer)
{
struct bpf_map *inner_map = ptr;
/* Defer the freeing of inner map according to the sleepable attribute
* of bpf program which owns the outer map, so unnecessary waiting for
* RCU tasks trace grace period can be avoided.
*/
if (need_defer) {
if (atomic64_read(&map->sleepable_refcnt))
WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true);
else
WRITE_ONCE(inner_map->free_after_rcu_gp, true);
}
bpf_map_put(inner_map);
}
u32 bpf_map_fd_sys_lookup_elem(void *ptr)
{
return ((struct bpf_map *)ptr)->id;
}
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