projects/linux·blob v4.2-rc2 · refs

257 lines · 6.5 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#include <linux/filter.h>
18
19/* Called from syscall */
20static struct bpf_map *array_map_alloc(union bpf_attr *attr)
21{
22 struct bpf_array *array;
23 u32 elem_size, array_size;
24
25 /* check sanity of attributes */
26 if (attr->max_entries == 0 || attr->key_size != 4 ||
27 attr->value_size == 0)
28 return ERR_PTR(-EINVAL);
29
30 elem_size = round_up(attr->value_size, 8);
31
32 /* check round_up into zero and u32 overflow */
33 if (elem_size == 0 ||
34 attr->max_entries > (U32_MAX - sizeof(*array)) / elem_size)
35 return ERR_PTR(-ENOMEM);
36
37 array_size = sizeof(*array) + attr->max_entries * elem_size;
38
39 /* allocate all map elements and zero-initialize them */
40 array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
41 if (!array) {
42 array = vzalloc(array_size);
43 if (!array)
44 return ERR_PTR(-ENOMEM);
45 }
46
47 /* copy mandatory map attributes */
48 array->map.key_size = attr->key_size;
49 array->map.value_size = attr->value_size;
50 array->map.max_entries = attr->max_entries;
51
52 array->elem_size = elem_size;
53
54 return &array->map;
55}
56
57/* Called from syscall or from eBPF program */
58static void *array_map_lookup_elem(struct bpf_map *map, void *key)
59{
60 struct bpf_array *array = container_of(map, struct bpf_array, map);
61 u32 index = *(u32 *)key;
62
63 if (index >= array->map.max_entries)
64 return NULL;
65
66 return array->value + array->elem_size * index;
67}
68
69/* Called from syscall */
70static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
71{
72 struct bpf_array *array = container_of(map, struct bpf_array, map);
73 u32 index = *(u32 *)key;
74 u32 *next = (u32 *)next_key;
75
76 if (index >= array->map.max_entries) {
77 *next = 0;
78 return 0;
79 }
80
81 if (index == array->map.max_entries - 1)
82 return -ENOENT;
83
84 *next = index + 1;
85 return 0;
86}
87
88/* Called from syscall or from eBPF program */
89static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
90 u64 map_flags)
91{
92 struct bpf_array *array = container_of(map, struct bpf_array, map);
93 u32 index = *(u32 *)key;
94
95 if (map_flags > BPF_EXIST)
96 /* unknown flags */
97 return -EINVAL;
98
99 if (index >= array->map.max_entries)
100 /* all elements were pre-allocated, cannot insert a new one */
101 return -E2BIG;
102
103 if (map_flags == BPF_NOEXIST)
104 /* all elements already exist */
105 return -EEXIST;
106
107 memcpy(array->value + array->elem_size * index, value, array->elem_size);
108 return 0;
109}
110
111/* Called from syscall or from eBPF program */
112static int array_map_delete_elem(struct bpf_map *map, void *key)
113{
114 return -EINVAL;
115}
116
117/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
118static void array_map_free(struct bpf_map *map)
119{
120 struct bpf_array *array = container_of(map, struct bpf_array, map);
121
122 /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
123 * so the programs (can be more than one that used this map) were
124 * disconnected from events. Wait for outstanding programs to complete
125 * and free the array
126 */
127 synchronize_rcu();
128
129 kvfree(array);
130}
131
132static const struct bpf_map_ops array_ops = {
133 .map_alloc = array_map_alloc,
134 .map_free = array_map_free,
135 .map_get_next_key = array_map_get_next_key,
136 .map_lookup_elem = array_map_lookup_elem,
137 .map_update_elem = array_map_update_elem,
138 .map_delete_elem = array_map_delete_elem,
139};
140
141static struct bpf_map_type_list array_type __read_mostly = {
142 .ops = &array_ops,
143 .type = BPF_MAP_TYPE_ARRAY,
144};
145
146static int __init register_array_map(void)
147{
148 bpf_register_map_type(&array_type);
149 return 0;
150}
151late_initcall(register_array_map);
152
153static struct bpf_map *prog_array_map_alloc(union bpf_attr *attr)
154{
155 /* only bpf_prog file descriptors can be stored in prog_array map */
156 if (attr->value_size != sizeof(u32))
157 return ERR_PTR(-EINVAL);
158 return array_map_alloc(attr);
159}
160
161static void prog_array_map_free(struct bpf_map *map)
162{
163 struct bpf_array *array = container_of(map, struct bpf_array, map);
164 int i;
165
166 synchronize_rcu();
167
168 /* make sure it's empty */
169 for (i = 0; i < array->map.max_entries; i++)
170 BUG_ON(array->prog[i] != NULL);
171 kvfree(array);
172}
173
174static void *prog_array_map_lookup_elem(struct bpf_map *map, void *key)
175{
176 return NULL;
177}
178
179/* only called from syscall */
180static int prog_array_map_update_elem(struct bpf_map *map, void *key,
181 void *value, u64 map_flags)
182{
183 struct bpf_array *array = container_of(map, struct bpf_array, map);
184 struct bpf_prog *prog, *old_prog;
185 u32 index = *(u32 *)key, ufd;
186
187 if (map_flags != BPF_ANY)
188 return -EINVAL;
189
190 if (index >= array->map.max_entries)
191 return -E2BIG;
192
193 ufd = *(u32 *)value;
194 prog = bpf_prog_get(ufd);
195 if (IS_ERR(prog))
196 return PTR_ERR(prog);
197
198 if (!bpf_prog_array_compatible(array, prog)) {
199 bpf_prog_put(prog);
200 return -EINVAL;
201 }
202
203 old_prog = xchg(array->prog + index, prog);
204 if (old_prog)
205 bpf_prog_put_rcu(old_prog);
206
207 return 0;
208}
209
210static int prog_array_map_delete_elem(struct bpf_map *map, void *key)
211{
212 struct bpf_array *array = container_of(map, struct bpf_array, map);
213 struct bpf_prog *old_prog;
214 u32 index = *(u32 *)key;
215
216 if (index >= array->map.max_entries)
217 return -E2BIG;
218
219 old_prog = xchg(array->prog + index, NULL);
220 if (old_prog) {
221 bpf_prog_put_rcu(old_prog);
222 return 0;
223 } else {
224 return -ENOENT;
225 }
226}
227
228/* decrement refcnt of all bpf_progs that are stored in this map */
229void bpf_prog_array_map_clear(struct bpf_map *map)
230{
231 struct bpf_array *array = container_of(map, struct bpf_array, map);
232 int i;
233
234 for (i = 0; i < array->map.max_entries; i++)
235 prog_array_map_delete_elem(map, &i);
236}
237
238static const struct bpf_map_ops prog_array_ops = {
239 .map_alloc = prog_array_map_alloc,
240 .map_free = prog_array_map_free,
241 .map_get_next_key = array_map_get_next_key,
242 .map_lookup_elem = prog_array_map_lookup_elem,
243 .map_update_elem = prog_array_map_update_elem,
244 .map_delete_elem = prog_array_map_delete_elem,
245};
246
247static struct bpf_map_type_list prog_array_type __read_mostly = {
248 .ops = &prog_array_ops,
249 .type = BPF_MAP_TYPE_PROG_ARRAY,
250};
251
252static int __init register_prog_array_map(void)
253{
254 bpf_register_map_type(&prog_array_type);
255 return 0;
256}
257late_initcall(register_prog_array_map);