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