projects/linux·blob v4.5-rc5 · refs

349 lines · 8.7 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#include <linux/perf_event.h>
19
20/* Called from syscall */
21static struct bpf_map *array_map_alloc(union bpf_attr *attr)
22{
23 struct bpf_array *array;
24 u32 elem_size, array_size;
25
26 /* check sanity of attributes */
27 if (attr->max_entries == 0 || attr->key_size != 4 ||
28 attr->value_size == 0)
29 return ERR_PTR(-EINVAL);
30
31 if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1))
32 /* if value_size is bigger, the user space won't be able to
33 * access the elements.
34 */
35 return ERR_PTR(-E2BIG);
36
37 elem_size = round_up(attr->value_size, 8);
38
39 /* check round_up into zero and u32 overflow */
40 if (elem_size == 0 ||
41 attr->max_entries > (U32_MAX - PAGE_SIZE - sizeof(*array)) / elem_size)
42 return ERR_PTR(-ENOMEM);
43
44 array_size = sizeof(*array) + attr->max_entries * elem_size;
45
46 /* allocate all map elements and zero-initialize them */
47 array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
48 if (!array) {
49 array = vzalloc(array_size);
50 if (!array)
51 return ERR_PTR(-ENOMEM);
52 }
53
54 /* copy mandatory map attributes */
55 array->map.key_size = attr->key_size;
56 array->map.value_size = attr->value_size;
57 array->map.max_entries = attr->max_entries;
58 array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
59 array->elem_size = elem_size;
60
61 return &array->map;
62}
63
64/* Called from syscall or from eBPF program */
65static void *array_map_lookup_elem(struct bpf_map *map, void *key)
66{
67 struct bpf_array *array = container_of(map, struct bpf_array, map);
68 u32 index = *(u32 *)key;
69
70 if (index >= array->map.max_entries)
71 return NULL;
72
73 return array->value + array->elem_size * index;
74}
75
76/* Called from syscall */
77static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
78{
79 struct bpf_array *array = container_of(map, struct bpf_array, map);
80 u32 index = *(u32 *)key;
81 u32 *next = (u32 *)next_key;
82
83 if (index >= array->map.max_entries) {
84 *next = 0;
85 return 0;
86 }
87
88 if (index == array->map.max_entries - 1)
89 return -ENOENT;
90
91 *next = index + 1;
92 return 0;
93}
94
95/* Called from syscall or from eBPF program */
96static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
97 u64 map_flags)
98{
99 struct bpf_array *array = container_of(map, struct bpf_array, map);
100 u32 index = *(u32 *)key;
101
102 if (map_flags > BPF_EXIST)
103 /* unknown flags */
104 return -EINVAL;
105
106 if (index >= array->map.max_entries)
107 /* all elements were pre-allocated, cannot insert a new one */
108 return -E2BIG;
109
110 if (map_flags == BPF_NOEXIST)
111 /* all elements already exist */
112 return -EEXIST;
113
114 memcpy(array->value + array->elem_size * index, value, map->value_size);
115 return 0;
116}
117
118/* Called from syscall or from eBPF program */
119static int array_map_delete_elem(struct bpf_map *map, void *key)
120{
121 return -EINVAL;
122}
123
124/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
125static void array_map_free(struct bpf_map *map)
126{
127 struct bpf_array *array = container_of(map, struct bpf_array, map);
128
129 /* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
130 * so the programs (can be more than one that used this map) were
131 * disconnected from events. Wait for outstanding programs to complete
132 * and free the array
133 */
134 synchronize_rcu();
135
136 kvfree(array);
137}
138
139static const struct bpf_map_ops array_ops = {
140 .map_alloc = array_map_alloc,
141 .map_free = array_map_free,
142 .map_get_next_key = array_map_get_next_key,
143 .map_lookup_elem = array_map_lookup_elem,
144 .map_update_elem = array_map_update_elem,
145 .map_delete_elem = array_map_delete_elem,
146};
147
148static struct bpf_map_type_list array_type __read_mostly = {
149 .ops = &array_ops,
150 .type = BPF_MAP_TYPE_ARRAY,
151};
152
153static int __init register_array_map(void)
154{
155 bpf_register_map_type(&array_type);
156 return 0;
157}
158late_initcall(register_array_map);
159
160static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
161{
162 /* only file descriptors can be stored in this type of map */
163 if (attr->value_size != sizeof(u32))
164 return ERR_PTR(-EINVAL);
165 return array_map_alloc(attr);
166}
167
168static void fd_array_map_free(struct bpf_map *map)
169{
170 struct bpf_array *array = container_of(map, struct bpf_array, map);
171 int i;
172
173 synchronize_rcu();
174
175 /* make sure it's empty */
176 for (i = 0; i < array->map.max_entries; i++)
177 BUG_ON(array->ptrs[i] != NULL);
178 kvfree(array);
179}
180
181static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
182{
183 return NULL;
184}
185
186/* only called from syscall */
187static int fd_array_map_update_elem(struct bpf_map *map, void *key,
188 void *value, u64 map_flags)
189{
190 struct bpf_array *array = container_of(map, struct bpf_array, map);
191 void *new_ptr, *old_ptr;
192 u32 index = *(u32 *)key, ufd;
193
194 if (map_flags != BPF_ANY)
195 return -EINVAL;
196
197 if (index >= array->map.max_entries)
198 return -E2BIG;
199
200 ufd = *(u32 *)value;
201 new_ptr = map->ops->map_fd_get_ptr(map, ufd);
202 if (IS_ERR(new_ptr))
203 return PTR_ERR(new_ptr);
204
205 old_ptr = xchg(array->ptrs + index, new_ptr);
206 if (old_ptr)
207 map->ops->map_fd_put_ptr(old_ptr);
208
209 return 0;
210}
211
212static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
213{
214 struct bpf_array *array = container_of(map, struct bpf_array, map);
215 void *old_ptr;
216 u32 index = *(u32 *)key;
217
218 if (index >= array->map.max_entries)
219 return -E2BIG;
220
221 old_ptr = xchg(array->ptrs + index, NULL);
222 if (old_ptr) {
223 map->ops->map_fd_put_ptr(old_ptr);
224 return 0;
225 } else {
226 return -ENOENT;
227 }
228}
229
230static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
231{
232 struct bpf_array *array = container_of(map, struct bpf_array, map);
233 struct bpf_prog *prog = bpf_prog_get(fd);
234 if (IS_ERR(prog))
235 return prog;
236
237 if (!bpf_prog_array_compatible(array, prog)) {
238 bpf_prog_put(prog);
239 return ERR_PTR(-EINVAL);
240 }
241 return prog;
242}
243
244static void prog_fd_array_put_ptr(void *ptr)
245{
246 struct bpf_prog *prog = ptr;
247
248 bpf_prog_put_rcu(prog);
249}
250
251/* decrement refcnt of all bpf_progs that are stored in this map */
252void bpf_fd_array_map_clear(struct bpf_map *map)
253{
254 struct bpf_array *array = container_of(map, struct bpf_array, map);
255 int i;
256
257 for (i = 0; i < array->map.max_entries; i++)
258 fd_array_map_delete_elem(map, &i);
259}
260
261static const struct bpf_map_ops prog_array_ops = {
262 .map_alloc = fd_array_map_alloc,
263 .map_free = fd_array_map_free,
264 .map_get_next_key = array_map_get_next_key,
265 .map_lookup_elem = fd_array_map_lookup_elem,
266 .map_update_elem = fd_array_map_update_elem,
267 .map_delete_elem = fd_array_map_delete_elem,
268 .map_fd_get_ptr = prog_fd_array_get_ptr,
269 .map_fd_put_ptr = prog_fd_array_put_ptr,
270};
271
272static struct bpf_map_type_list prog_array_type __read_mostly = {
273 .ops = &prog_array_ops,
274 .type = BPF_MAP_TYPE_PROG_ARRAY,
275};
276
277static int __init register_prog_array_map(void)
278{
279 bpf_register_map_type(&prog_array_type);
280 return 0;
281}
282late_initcall(register_prog_array_map);
283
284static void perf_event_array_map_free(struct bpf_map *map)
285{
286 bpf_fd_array_map_clear(map);
287 fd_array_map_free(map);
288}
289
290static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
291{
292 struct perf_event *event;
293 const struct perf_event_attr *attr;
294 struct file *file;
295
296 file = perf_event_get(fd);
297 if (IS_ERR(file))
298 return file;
299
300 event = file->private_data;
301
302 attr = perf_event_attrs(event);
303 if (IS_ERR(attr))
304 goto err;
305
306 if (attr->inherit)
307 goto err;
308
309 if (attr->type == PERF_TYPE_RAW)
310 return file;
311
312 if (attr->type == PERF_TYPE_HARDWARE)
313 return file;
314
315 if (attr->type == PERF_TYPE_SOFTWARE &&
316 attr->config == PERF_COUNT_SW_BPF_OUTPUT)
317 return file;
318err:
319 fput(file);
320 return ERR_PTR(-EINVAL);
321}
322
323static void perf_event_fd_array_put_ptr(void *ptr)
324{
325 fput((struct file *)ptr);
326}
327
328static const struct bpf_map_ops perf_event_array_ops = {
329 .map_alloc = fd_array_map_alloc,
330 .map_free = perf_event_array_map_free,
331 .map_get_next_key = array_map_get_next_key,
332 .map_lookup_elem = fd_array_map_lookup_elem,
333 .map_update_elem = fd_array_map_update_elem,
334 .map_delete_elem = fd_array_map_delete_elem,
335 .map_fd_get_ptr = perf_event_fd_array_get_ptr,
336 .map_fd_put_ptr = perf_event_fd_array_put_ptr,
337};
338
339static struct bpf_map_type_list perf_event_array_type __read_mostly = {
340 .ops = &perf_event_array_ops,
341 .type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
342};
343
344static int __init register_perf_event_array_map(void)
345{
346 bpf_register_map_type(&perf_event_array_type);
347 return 0;
348}
349late_initcall(register_perf_event_array_map);