/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com * * This program is free software; you can redistribute it and/or * modify it under the terms of version 2 of the GNU General Public * License as published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. */#include <linux/bpf.h>#include <linux/err.h>#include <linux/vmalloc.h>#include <linux/slab.h>#include <linux/mm.h> struct bpf_array {	struct bpf_map map;	u32 elem_size;	char value[0] __aligned(8);}; /* Called from syscall */static struct bpf_map *array_map_alloc(union bpf_attr *attr){	struct bpf_array *array;	u32 elem_size, array_size; 	/* check sanity of attributes */	if (attr->max_entries == 0 || attr->key_size != 4 ||	    attr->value_size == 0)		return ERR_PTR(-EINVAL); 	elem_size = round_up(attr->value_size, 8); 	/* check round_up into zero and u32 overflow */	if (elem_size == 0 ||	    attr->max_entries > (U32_MAX - sizeof(*array)) / elem_size)		return ERR_PTR(-ENOMEM); 	array_size = sizeof(*array) + attr->max_entries * elem_size; 	/* allocate all map elements and zero-initialize them */	array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);	if (!array) {		array = vzalloc(array_size);		if (!array)			return ERR_PTR(-ENOMEM);	} 	/* copy mandatory map attributes */	array->map.key_size = attr->key_size;	array->map.value_size = attr->value_size;	array->map.max_entries = attr->max_entries; 	array->elem_size = elem_size; 	return &array->map;} /* Called from syscall or from eBPF program */static void *array_map_lookup_elem(struct bpf_map *map, void *key){	struct bpf_array *array = container_of(map, struct bpf_array, map);	u32 index = *(u32 *)key; 	if (index >= array->map.max_entries)		return NULL; 	return array->value + array->elem_size * index;} /* Called from syscall */static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key){	struct bpf_array *array = container_of(map, struct bpf_array, map);	u32 index = *(u32 *)key;	u32 *next = (u32 *)next_key; 	if (index >= array->map.max_entries) {		*next = 0;		return 0;	} 	if (index == array->map.max_entries - 1)		return -ENOENT; 	*next = index + 1;	return 0;} /* Called from syscall or from eBPF program */static int array_map_update_elem(struct bpf_map *map, void *key, void *value,				 u64 map_flags){	struct bpf_array *array = container_of(map, struct bpf_array, map);	u32 index = *(u32 *)key; 	if (map_flags > BPF_EXIST)		/* unknown flags */		return -EINVAL; 	if (index >= array->map.max_entries)		/* all elements were pre-allocated, cannot insert a new one */		return -E2BIG; 	if (map_flags == BPF_NOEXIST)		/* all elements already exist */		return -EEXIST; 	memcpy(array->value + array->elem_size * index, value, array->elem_size);	return 0;} /* Called from syscall or from eBPF program */static int array_map_delete_elem(struct bpf_map *map, void *key){	return -EINVAL;} /* Called when map->refcnt goes to zero, either from workqueue or from syscall */static void array_map_free(struct bpf_map *map){	struct bpf_array *array = container_of(map, struct bpf_array, map); 	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,	 * so the programs (can be more than one that used this map) were	 * disconnected from events. Wait for outstanding programs to complete	 * and free the array	 */	synchronize_rcu(); 	kvfree(array);} static struct bpf_map_ops array_ops = {	.map_alloc = array_map_alloc,	.map_free = array_map_free,	.map_get_next_key = array_map_get_next_key,	.map_lookup_elem = array_map_lookup_elem,	.map_update_elem = array_map_update_elem,	.map_delete_elem = array_map_delete_elem,}; static struct bpf_map_type_list tl = {	.ops = &array_ops,	.type = BPF_MAP_TYPE_ARRAY,}; static int __init register_array_map(void){	bpf_register_map_type(&tl);	return 0;}late_initcall(register_array_map);