projects/linux·blob v3.19-rc5 · refs

156 lines · 4.0 KiB

1/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
2 *
3 * This program is free software; you can redistribute it and/or
4 * modify it under the terms of version 2 of the GNU General Public
5 * License as published by the Free Software Foundation.
6 *
7 * This program is distributed in the hope that it will be useful, but
8 * WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
10 * General Public License for more details.
11 */
12#include <linux/bpf.h>
13#include <linux/err.h>
14#include <linux/vmalloc.h>
15#include <linux/slab.h>
16#include <linux/mm.h>
17
18struct bpf_array {
19 struct bpf_map map;
20 u32 elem_size;
21 char value[0] __aligned(8);
22};
23
24/* Called from syscall */
25static struct bpf_map *array_map_alloc(union bpf_attr *attr)
26{
27 struct bpf_array *array;
28 u32 elem_size, array_size;
29
30 /* check sanity of attributes */
31 if (attr->max_entries == 0 || attr->key_size != 4 ||
32 attr->value_size == 0)
33 return ERR_PTR(-EINVAL);
34
35 elem_size = round_up(attr->value_size, 8);
36
37 /* check round_up into zero and u32 overflow */
38 if (elem_size == 0 ||
39 attr->max_entries > (U32_MAX - sizeof(*array)) / elem_size)
40 return ERR_PTR(-ENOMEM);
41
42 array_size = sizeof(*array) + attr->max_entries * elem_size;
43
44 /* allocate all map elements and zero-initialize them */
45 array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
46 if (!array) {
47 array = vzalloc(array_size);
48 if (!array)
49 return ERR_PTR(-ENOMEM);
50 }
51
52 /* copy mandatory map attributes */
53 array->map.key_size = attr->key_size;
54 array->map.value_size = attr->value_size;
55 array->map.max_entries = attr->max_entries;
56
57 array->elem_size = elem_size;
58
59 return &array->map;
60}
61
62/* Called from syscall or from eBPF program */
63static void *array_map_lookup_elem(struct bpf_map *map, void *key)
64{
65 struct bpf_array *array = container_of(map, struct bpf_array, map);
66 u32 index = *(u32 *)key;
67
68 if (index >= array->map.max_entries)
69 return NULL;
70
71 return array->value + array->elem_size * index;
72}
73
74/* Called from syscall */
75static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
76{
77 struct bpf_array *array = container_of(map, struct bpf_array, map);
78 u32 index = *(u32 *)key;
79 u32 *next = (u32 *)next_key;
80
81 if (index >= array->map.max_entries) {
82 *next = 0;
83 return 0;
84 }
85
86 if (index == array->map.max_entries - 1)
87 return -ENOENT;
88
89 *next = index + 1;
90 return 0;
91}
92
93/* Called from syscall or from eBPF program */
94static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
95 u64 map_flags)
96{
97 struct bpf_array *array = container_of(map, struct bpf_array, map);
98 u32 index = *(u32 *)key;
99
100 if (map_flags > BPF_EXIST)
101 /* unknown flags */
102 return -EINVAL;
103
104 if (index >= array->map.max_entries)
105 /* all elements were pre-allocated, cannot insert a new one */
106 return -E2BIG;
107
108 if (map_flags == BPF_NOEXIST)
109 /* all elements already exist */
110 return -EEXIST;
111
112 memcpy(array->value + array->elem_size * index, value, array->elem_size);
113 return 0;
114}
115
116/* Called from syscall or from eBPF program */
117static int array_map_delete_elem(struct bpf_map *map, void *key)
118{
119 return -EINVAL;
120}
121
122/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
123static void array_map_free(struct bpf_map *map)
124{
125 struct bpf_array *array = container_of(map, struct bpf_array, map);
126
127 /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
128 * so the programs (can be more than one that used this map) were
129 * disconnected from events. Wait for outstanding programs to complete
130 * and free the array
131 */
132 synchronize_rcu();
133
134 kvfree(array);
135}
136
137static struct bpf_map_ops array_ops = {
138 .map_alloc = array_map_alloc,
139 .map_free = array_map_free,
140 .map_get_next_key = array_map_get_next_key,
141 .map_lookup_elem = array_map_lookup_elem,
142 .map_update_elem = array_map_update_elem,
143 .map_delete_elem = array_map_delete_elem,
144};
145
146static struct bpf_map_type_list tl = {
147 .ops = &array_ops,
148 .type = BPF_MAP_TYPE_ARRAY,
149};
150
151static int __init register_array_map(void)
152{
153 bpf_register_map_type(&tl);
154 return 0;
155}
156late_initcall(register_array_map);