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
 20static void bpf_array_free_percpu(struct bpf_array *array)
 21{
 22	int i;
 23
 24	for (i = 0; i < array->map.max_entries; i++)
 25		free_percpu(array->pptrs[i]);
 26}
 27
 28static int bpf_array_alloc_percpu(struct bpf_array *array)
 29{
 30	void __percpu *ptr;
 31	int i;
 32
 33	for (i = 0; i < array->map.max_entries; i++) {
 34		ptr = __alloc_percpu_gfp(array->elem_size, 8,
 35					 GFP_USER | __GFP_NOWARN);
 36		if (!ptr) {
 37			bpf_array_free_percpu(array);
 38			return -ENOMEM;
 39		}
 40		array->pptrs[i] = ptr;
 41	}
 42
 43	return 0;
 44}
 45
 46/* Called from syscall */
 47static struct bpf_map *array_map_alloc(union bpf_attr *attr)
 48{
 49	bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY;
 50	struct bpf_array *array;
 51	u64 array_size;
 52	u32 elem_size;
 53
 54	/* check sanity of attributes */
 55	if (attr->max_entries == 0 || attr->key_size != 4 ||
 56	    attr->value_size == 0 || attr->map_flags)
 57		return ERR_PTR(-EINVAL);
 58
 59	if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1))
 60		/* if value_size is bigger, the user space won't be able to
 61		 * access the elements.
 62		 */
 63		return ERR_PTR(-E2BIG);
 64
 65	elem_size = round_up(attr->value_size, 8);
 66
 67	array_size = sizeof(*array);
 68	if (percpu)
 69		array_size += (u64) attr->max_entries * sizeof(void *);
 70	else
 71		array_size += (u64) attr->max_entries * elem_size;
 72
 73	/* make sure there is no u32 overflow later in round_up() */
 74	if (array_size >= U32_MAX - PAGE_SIZE)
 75		return ERR_PTR(-ENOMEM);
 76
 77
 78	/* allocate all map elements and zero-initialize them */
 79	array = kzalloc(array_size, GFP_USER | __GFP_NOWARN);
 80	if (!array) {
 81		array = vzalloc(array_size);
 82		if (!array)
 83			return ERR_PTR(-ENOMEM);
 84	}
 85
 86	/* copy mandatory map attributes */
 87	array->map.map_type = attr->map_type;
 88	array->map.key_size = attr->key_size;
 89	array->map.value_size = attr->value_size;
 90	array->map.max_entries = attr->max_entries;
 91	array->elem_size = elem_size;
 92
 93	if (!percpu)
 94		goto out;
 95
 96	array_size += (u64) attr->max_entries * elem_size * num_possible_cpus();
 97
 98	if (array_size >= U32_MAX - PAGE_SIZE ||
 99	    elem_size > PCPU_MIN_UNIT_SIZE || bpf_array_alloc_percpu(array)) {
100		kvfree(array);
101		return ERR_PTR(-ENOMEM);
102	}
103out:
104	array->map.pages = round_up(array_size, PAGE_SIZE) >> PAGE_SHIFT;
105
106	return &array->map;
107}
108
109/* Called from syscall or from eBPF program */
110static void *array_map_lookup_elem(struct bpf_map *map, void *key)
111{
112	struct bpf_array *array = container_of(map, struct bpf_array, map);
113	u32 index = *(u32 *)key;
114
115	if (unlikely(index >= array->map.max_entries))
116		return NULL;
117
118	return array->value + array->elem_size * index;
119}
120
121/* Called from eBPF program */
122static void *percpu_array_map_lookup_elem(struct bpf_map *map, void *key)
123{
124	struct bpf_array *array = container_of(map, struct bpf_array, map);
125	u32 index = *(u32 *)key;
126
127	if (unlikely(index >= array->map.max_entries))
128		return NULL;
129
130	return this_cpu_ptr(array->pptrs[index]);
131}
132
133int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value)
134{
135	struct bpf_array *array = container_of(map, struct bpf_array, map);
136	u32 index = *(u32 *)key;
137	void __percpu *pptr;
138	int cpu, off = 0;
139	u32 size;
140
141	if (unlikely(index >= array->map.max_entries))
142		return -ENOENT;
143
144	/* per_cpu areas are zero-filled and bpf programs can only
145	 * access 'value_size' of them, so copying rounded areas
146	 * will not leak any kernel data
147	 */
148	size = round_up(map->value_size, 8);
149	rcu_read_lock();
150	pptr = array->pptrs[index];
151	for_each_possible_cpu(cpu) {
152		bpf_long_memcpy(value + off, per_cpu_ptr(pptr, cpu), size);
153		off += size;
154	}
155	rcu_read_unlock();
156	return 0;
157}
158
159/* Called from syscall */
160static int array_map_get_next_key(struct bpf_map *map, void *key, void *next_key)
161{
162	struct bpf_array *array = container_of(map, struct bpf_array, map);
163	u32 index = *(u32 *)key;
164	u32 *next = (u32 *)next_key;
165
166	if (index >= array->map.max_entries) {
167		*next = 0;
168		return 0;
169	}
170
171	if (index == array->map.max_entries - 1)
172		return -ENOENT;
173
174	*next = index + 1;
175	return 0;
176}
177
178/* Called from syscall or from eBPF program */
179static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
180				 u64 map_flags)
181{
182	struct bpf_array *array = container_of(map, struct bpf_array, map);
183	u32 index = *(u32 *)key;
184
185	if (unlikely(map_flags > BPF_EXIST))
186		/* unknown flags */
187		return -EINVAL;
188
189	if (unlikely(index >= array->map.max_entries))
190		/* all elements were pre-allocated, cannot insert a new one */
191		return -E2BIG;
192
193	if (unlikely(map_flags == BPF_NOEXIST))
194		/* all elements already exist */
195		return -EEXIST;
196
197	if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
198		memcpy(this_cpu_ptr(array->pptrs[index]),
199		       value, map->value_size);
200	else
201		memcpy(array->value + array->elem_size * index,
202		       value, map->value_size);
203	return 0;
204}
205
206int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
207			    u64 map_flags)
208{
209	struct bpf_array *array = container_of(map, struct bpf_array, map);
210	u32 index = *(u32 *)key;
211	void __percpu *pptr;
212	int cpu, off = 0;
213	u32 size;
214
215	if (unlikely(map_flags > BPF_EXIST))
216		/* unknown flags */
217		return -EINVAL;
218
219	if (unlikely(index >= array->map.max_entries))
220		/* all elements were pre-allocated, cannot insert a new one */
221		return -E2BIG;
222
223	if (unlikely(map_flags == BPF_NOEXIST))
224		/* all elements already exist */
225		return -EEXIST;
226
227	/* the user space will provide round_up(value_size, 8) bytes that
228	 * will be copied into per-cpu area. bpf programs can only access
229	 * value_size of it. During lookup the same extra bytes will be
230	 * returned or zeros which were zero-filled by percpu_alloc,
231	 * so no kernel data leaks possible
232	 */
233	size = round_up(map->value_size, 8);
234	rcu_read_lock();
235	pptr = array->pptrs[index];
236	for_each_possible_cpu(cpu) {
237		bpf_long_memcpy(per_cpu_ptr(pptr, cpu), value + off, size);
238		off += size;
239	}
240	rcu_read_unlock();
241	return 0;
242}
243
244/* Called from syscall or from eBPF program */
245static int array_map_delete_elem(struct bpf_map *map, void *key)
246{
247	return -EINVAL;
248}
249
250/* Called when map->refcnt goes to zero, either from workqueue or from syscall */
251static void array_map_free(struct bpf_map *map)
252{
253	struct bpf_array *array = container_of(map, struct bpf_array, map);
254
255	/* at this point bpf_prog->aux->refcnt == 0 and this map->refcnt == 0,
256	 * so the programs (can be more than one that used this map) were
257	 * disconnected from events. Wait for outstanding programs to complete
258	 * and free the array
259	 */
260	synchronize_rcu();
261
262	if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
263		bpf_array_free_percpu(array);
264
265	kvfree(array);
266}
267
268static const struct bpf_map_ops array_ops = {
269	.map_alloc = array_map_alloc,
270	.map_free = array_map_free,
271	.map_get_next_key = array_map_get_next_key,
272	.map_lookup_elem = array_map_lookup_elem,
273	.map_update_elem = array_map_update_elem,
274	.map_delete_elem = array_map_delete_elem,
275};
276
277static struct bpf_map_type_list array_type __read_mostly = {
278	.ops = &array_ops,
279	.type = BPF_MAP_TYPE_ARRAY,
280};
281
282static const struct bpf_map_ops percpu_array_ops = {
283	.map_alloc = array_map_alloc,
284	.map_free = array_map_free,
285	.map_get_next_key = array_map_get_next_key,
286	.map_lookup_elem = percpu_array_map_lookup_elem,
287	.map_update_elem = array_map_update_elem,
288	.map_delete_elem = array_map_delete_elem,
289};
290
291static struct bpf_map_type_list percpu_array_type __read_mostly = {
292	.ops = &percpu_array_ops,
293	.type = BPF_MAP_TYPE_PERCPU_ARRAY,
294};
295
296static int __init register_array_map(void)
297{
298	bpf_register_map_type(&array_type);
299	bpf_register_map_type(&percpu_array_type);
300	return 0;
301}
302late_initcall(register_array_map);
303
304static struct bpf_map *fd_array_map_alloc(union bpf_attr *attr)
305{
306	/* only file descriptors can be stored in this type of map */
307	if (attr->value_size != sizeof(u32))
308		return ERR_PTR(-EINVAL);
309	return array_map_alloc(attr);
310}
311
312static void fd_array_map_free(struct bpf_map *map)
313{
314	struct bpf_array *array = container_of(map, struct bpf_array, map);
315	int i;
316
317	synchronize_rcu();
318
319	/* make sure it's empty */
320	for (i = 0; i < array->map.max_entries; i++)
321		BUG_ON(array->ptrs[i] != NULL);
322	kvfree(array);
323}
324
325static void *fd_array_map_lookup_elem(struct bpf_map *map, void *key)
326{
327	return NULL;
328}
329
330/* only called from syscall */
331static int fd_array_map_update_elem(struct bpf_map *map, void *key,
332				    void *value, u64 map_flags)
333{
334	struct bpf_array *array = container_of(map, struct bpf_array, map);
335	void *new_ptr, *old_ptr;
336	u32 index = *(u32 *)key, ufd;
337
338	if (map_flags != BPF_ANY)
339		return -EINVAL;
340
341	if (index >= array->map.max_entries)
342		return -E2BIG;
343
344	ufd = *(u32 *)value;
345	new_ptr = map->ops->map_fd_get_ptr(map, ufd);
346	if (IS_ERR(new_ptr))
347		return PTR_ERR(new_ptr);
348
349	old_ptr = xchg(array->ptrs + index, new_ptr);
350	if (old_ptr)
351		map->ops->map_fd_put_ptr(old_ptr);
352
353	return 0;
354}
355
356static int fd_array_map_delete_elem(struct bpf_map *map, void *key)
357{
358	struct bpf_array *array = container_of(map, struct bpf_array, map);
359	void *old_ptr;
360	u32 index = *(u32 *)key;
361
362	if (index >= array->map.max_entries)
363		return -E2BIG;
364
365	old_ptr = xchg(array->ptrs + index, NULL);
366	if (old_ptr) {
367		map->ops->map_fd_put_ptr(old_ptr);
368		return 0;
369	} else {
370		return -ENOENT;
371	}
372}
373
374static void *prog_fd_array_get_ptr(struct bpf_map *map, int fd)
375{
376	struct bpf_array *array = container_of(map, struct bpf_array, map);
377	struct bpf_prog *prog = bpf_prog_get(fd);
378	if (IS_ERR(prog))
379		return prog;
380
381	if (!bpf_prog_array_compatible(array, prog)) {
382		bpf_prog_put(prog);
383		return ERR_PTR(-EINVAL);
384	}
385	return prog;
386}
387
388static void prog_fd_array_put_ptr(void *ptr)
389{
390	struct bpf_prog *prog = ptr;
391
392	bpf_prog_put_rcu(prog);
393}
394
395/* decrement refcnt of all bpf_progs that are stored in this map */
396void bpf_fd_array_map_clear(struct bpf_map *map)
397{
398	struct bpf_array *array = container_of(map, struct bpf_array, map);
399	int i;
400
401	for (i = 0; i < array->map.max_entries; i++)
402		fd_array_map_delete_elem(map, &i);
403}
404
405static const struct bpf_map_ops prog_array_ops = {
406	.map_alloc = fd_array_map_alloc,
407	.map_free = fd_array_map_free,
408	.map_get_next_key = array_map_get_next_key,
409	.map_lookup_elem = fd_array_map_lookup_elem,
410	.map_update_elem = fd_array_map_update_elem,
411	.map_delete_elem = fd_array_map_delete_elem,
412	.map_fd_get_ptr = prog_fd_array_get_ptr,
413	.map_fd_put_ptr = prog_fd_array_put_ptr,
414};
415
416static struct bpf_map_type_list prog_array_type __read_mostly = {
417	.ops = &prog_array_ops,
418	.type = BPF_MAP_TYPE_PROG_ARRAY,
419};
420
421static int __init register_prog_array_map(void)
422{
423	bpf_register_map_type(&prog_array_type);
424	return 0;
425}
426late_initcall(register_prog_array_map);
427
428static void perf_event_array_map_free(struct bpf_map *map)
429{
430	bpf_fd_array_map_clear(map);
431	fd_array_map_free(map);
432}
433
434static void *perf_event_fd_array_get_ptr(struct bpf_map *map, int fd)
435{
436	struct perf_event *event;
437	const struct perf_event_attr *attr;
438	struct file *file;
439
440	file = perf_event_get(fd);
441	if (IS_ERR(file))
442		return file;
443
444	event = file->private_data;
445
446	attr = perf_event_attrs(event);
447	if (IS_ERR(attr))
448		goto err;
449
450	if (attr->inherit)
451		goto err;
452
453	if (attr->type == PERF_TYPE_RAW)
454		return file;
455
456	if (attr->type == PERF_TYPE_HARDWARE)
457		return file;
458
459	if (attr->type == PERF_TYPE_SOFTWARE &&
460	    attr->config == PERF_COUNT_SW_BPF_OUTPUT)
461		return file;
462err:
463	fput(file);
464	return ERR_PTR(-EINVAL);
465}
466
467static void perf_event_fd_array_put_ptr(void *ptr)
468{
469	fput((struct file *)ptr);
470}
471
472static const struct bpf_map_ops perf_event_array_ops = {
473	.map_alloc = fd_array_map_alloc,
474	.map_free = perf_event_array_map_free,
475	.map_get_next_key = array_map_get_next_key,
476	.map_lookup_elem = fd_array_map_lookup_elem,
477	.map_update_elem = fd_array_map_update_elem,
478	.map_delete_elem = fd_array_map_delete_elem,
479	.map_fd_get_ptr = perf_event_fd_array_get_ptr,
480	.map_fd_put_ptr = perf_event_fd_array_put_ptr,
481};
482
483static struct bpf_map_type_list perf_event_array_type __read_mostly = {
484	.ops = &perf_event_array_ops,
485	.type = BPF_MAP_TYPE_PERF_EVENT_ARRAY,
486};
487
488static int __init register_perf_event_array_map(void)
489{
490	bpf_register_map_type(&perf_event_array_type);
491	return 0;
492}
493late_initcall(register_perf_event_array_map);