diff options
Diffstat (limited to 'kernel/bpf/map_in_map.c')
| -rw-r--r-- | kernel/bpf/map_in_map.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/kernel/bpf/map_in_map.c b/kernel/bpf/map_in_map.c new file mode 100644 index 0000000000..3248ff5d81 --- /dev/null +++ b/kernel/bpf/map_in_map.c @@ -0,0 +1,146 @@ +// 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_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) { + 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; + + /* The inner map may still be used by both non-sleepable and sleepable + * bpf program, so free it after one RCU grace period and one tasks + * trace RCU grace period. + */ + if (need_defer) + WRITE_ONCE(inner_map->free_after_mult_rcu_gp, true); + bpf_map_put(inner_map); +} + +u32 bpf_map_fd_sys_lookup_elem(void *ptr) +{ + return ((struct bpf_map *)ptr)->id; +} |