/* 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 const 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 array_type __read_mostly = { .ops = &array_ops, .type = BPF_MAP_TYPE_ARRAY, }; static int __init register_array_map(void) { bpf_register_map_type(&array_type); return 0; } late_initcall(register_array_map);