fd_array.c

  1// SPDX-License-Identifier: GPL-2.0
  2
  3#include <test_progs.h>
  4
  5#include <linux/btf.h>
  6#include <bpf/bpf.h>
  7
  8#include "../test_btf.h"
  9
 10static inline int new_map(void)
 11{
 12	const char *name = NULL;
 13	__u32 max_entries = 1;
 14	__u32 value_size = 8;
 15	__u32 key_size = 4;
 16
 17	return bpf_map_create(BPF_MAP_TYPE_ARRAY, name,
 18			      key_size, value_size,
 19			      max_entries, NULL);
 20}
 21
 22static int new_btf(void)
 23{
 24	struct btf_blob {
 25		struct btf_header btf_hdr;
 26		__u32 types[8];
 27		__u32 str;
 28	} raw_btf = {
 29		.btf_hdr = {
 30			.magic = BTF_MAGIC,
 31			.version = BTF_VERSION,
 32			.hdr_len = sizeof(struct btf_header),
 33			.type_len = sizeof(raw_btf.types),
 34			.str_off = offsetof(struct btf_blob, str) - offsetof(struct btf_blob, types),
 35			.str_len = sizeof(raw_btf.str),
 36		},
 37		.types = {
 38			/* long */
 39			BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 64, 8),  /* [1] */
 40			/* unsigned long */
 41			BTF_TYPE_INT_ENC(0, 0, 0, 64, 8),  /* [2] */
 42		},
 43	};
 44
 45	return bpf_btf_load(&raw_btf, sizeof(raw_btf), NULL);
 46}
 47
 48#define Close(FD) do {		\
 49	if ((FD) >= 0) {	\
 50		close(FD);	\
 51		FD = -1;	\
 52	}			\
 53} while(0)
 54
 55static bool map_exists(__u32 id)
 56{
 57	int fd;
 58
 59	fd = bpf_map_get_fd_by_id(id);
 60	if (fd >= 0) {
 61		close(fd);
 62		return true;
 63	}
 64	return false;
 65}
 66
 67static bool btf_exists(__u32 id)
 68{
 69	int fd;
 70
 71	fd = bpf_btf_get_fd_by_id(id);
 72	if (fd >= 0) {
 73		close(fd);
 74		return true;
 75	}
 76	return false;
 77}
 78
 79static inline int bpf_prog_get_map_ids(int prog_fd, __u32 *nr_map_ids, __u32 *map_ids)
 80{
 81	__u32 len = sizeof(struct bpf_prog_info);
 82	struct bpf_prog_info info;
 83	int err;
 84
 85	memset(&info, 0, len);
 86	info.nr_map_ids = *nr_map_ids;
 87	info.map_ids = ptr_to_u64(map_ids);
 88
 89	err = bpf_prog_get_info_by_fd(prog_fd, &info, &len);
 90	if (!ASSERT_OK(err, "bpf_prog_get_info_by_fd"))
 91		return -1;
 92
 93	*nr_map_ids = info.nr_map_ids;
 94
 95	return 0;
 96}
 97
 98static int __load_test_prog(int map_fd, const int *fd_array, int fd_array_cnt)
 99{
100	/* A trivial program which uses one map */
101	struct bpf_insn insns[] = {
102		BPF_LD_MAP_FD(BPF_REG_1, map_fd),
103		BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
104		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
105		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
106		BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
107		BPF_MOV64_IMM(BPF_REG_0, 0),
108		BPF_EXIT_INSN(),
109	};
110	LIBBPF_OPTS(bpf_prog_load_opts, opts);
111
112	opts.fd_array = fd_array;
113	opts.fd_array_cnt = fd_array_cnt;
114
115	return bpf_prog_load(BPF_PROG_TYPE_XDP, NULL, "GPL", insns, ARRAY_SIZE(insns), &opts);
116}
117
118static int load_test_prog(const int *fd_array, int fd_array_cnt)
119{
120	int map_fd;
121	int ret;
122
123	map_fd = new_map();
124	if (!ASSERT_GE(map_fd, 0, "new_map"))
125		return map_fd;
126
127	ret = __load_test_prog(map_fd, fd_array, fd_array_cnt);
128	close(map_fd);
129	return ret;
130}
131
132static bool check_expected_map_ids(int prog_fd, int expected, __u32 *map_ids, __u32 *nr_map_ids)
133{
134	int err;
135
136	err = bpf_prog_get_map_ids(prog_fd, nr_map_ids, map_ids);
137	if (!ASSERT_OK(err, "bpf_prog_get_map_ids"))
138		return false;
139	if (!ASSERT_EQ(*nr_map_ids, expected, "unexpected nr_map_ids"))
140		return false;
141
142	return true;
143}
144
145/*
146 * Load a program, which uses one map. No fd_array maps are present.
147 * On return only one map is expected to be bound to prog.
148 */
149static void check_fd_array_cnt__no_fd_array(void)
150{
151	__u32 map_ids[16];
152	__u32 nr_map_ids;
153	int prog_fd = -1;
154
155	prog_fd = load_test_prog(NULL, 0);
156	if (!ASSERT_GE(prog_fd, 0, "BPF_PROG_LOAD"))
157		return;
158	nr_map_ids = ARRAY_SIZE(map_ids);
159	check_expected_map_ids(prog_fd, 1, map_ids, &nr_map_ids);
160	close(prog_fd);
161}
162
163/*
164 * Load a program, which uses one map, and pass two extra, non-equal, maps in
165 * fd_array with fd_array_cnt=2. On return three maps are expected to be bound
166 * to the program.
167 */
168static void check_fd_array_cnt__fd_array_ok(void)
169{
170	int extra_fds[2] = { -1, -1 };
171	__u32 map_ids[16];
172	__u32 nr_map_ids;
173	int prog_fd = -1;
174
175	extra_fds[0] = new_map();
176	if (!ASSERT_GE(extra_fds[0], 0, "new_map"))
177		goto cleanup;
178	extra_fds[1] = new_map();
179	if (!ASSERT_GE(extra_fds[1], 0, "new_map"))
180		goto cleanup;
181	prog_fd = load_test_prog(extra_fds, 2);
182	if (!ASSERT_GE(prog_fd, 0, "BPF_PROG_LOAD"))
183		goto cleanup;
184	nr_map_ids = ARRAY_SIZE(map_ids);
185	if (!check_expected_map_ids(prog_fd, 3, map_ids, &nr_map_ids))
186		goto cleanup;
187
188	/* maps should still exist when original file descriptors are closed */
189	Close(extra_fds[0]);
190	Close(extra_fds[1]);
191	if (!ASSERT_EQ(map_exists(map_ids[0]), true, "map_ids[0] should exist"))
192		goto cleanup;
193	if (!ASSERT_EQ(map_exists(map_ids[1]), true, "map_ids[1] should exist"))
194		goto cleanup;
195
196	/* some fds might be invalid, so ignore return codes */
197cleanup:
198	Close(extra_fds[1]);
199	Close(extra_fds[0]);
200	Close(prog_fd);
201}
202
203/*
204 * Load a program with a few extra maps duplicated in the fd_array.
205 * After the load maps should only be referenced once.
206 */
207static void check_fd_array_cnt__duplicated_maps(void)
208{
209	int extra_fds[4] = { -1, -1, -1, -1 };
210	__u32 map_ids[16];
211	__u32 nr_map_ids;
212	int prog_fd = -1;
213
214	extra_fds[0] = extra_fds[2] = new_map();
215	if (!ASSERT_GE(extra_fds[0], 0, "new_map"))
216		goto cleanup;
217	extra_fds[1] = extra_fds[3] = new_map();
218	if (!ASSERT_GE(extra_fds[1], 0, "new_map"))
219		goto cleanup;
220	prog_fd = load_test_prog(extra_fds, 4);
221	if (!ASSERT_GE(prog_fd, 0, "BPF_PROG_LOAD"))
222		goto cleanup;
223	nr_map_ids = ARRAY_SIZE(map_ids);
224	if (!check_expected_map_ids(prog_fd, 3, map_ids, &nr_map_ids))
225		goto cleanup;
226
227	/* maps should still exist when original file descriptors are closed */
228	Close(extra_fds[0]);
229	Close(extra_fds[1]);
230	if (!ASSERT_EQ(map_exists(map_ids[0]), true, "map should exist"))
231		goto cleanup;
232	if (!ASSERT_EQ(map_exists(map_ids[1]), true, "map should exist"))
233		goto cleanup;
234
235	/* some fds might be invalid, so ignore return codes */
236cleanup:
237	Close(extra_fds[1]);
238	Close(extra_fds[0]);
239	Close(prog_fd);
240}
241
242/*
243 * Check that if maps which are referenced by a program are
244 * passed in fd_array, then they will be referenced only once
245 */
246static void check_fd_array_cnt__referenced_maps_in_fd_array(void)
247{
248	int extra_fds[1] = { -1 };
249	__u32 map_ids[16];
250	__u32 nr_map_ids;
251	int prog_fd = -1;
252
253	extra_fds[0] = new_map();
254	if (!ASSERT_GE(extra_fds[0], 0, "new_map"))
255		goto cleanup;
256	prog_fd = __load_test_prog(extra_fds[0], extra_fds, 1);
257	if (!ASSERT_GE(prog_fd, 0, "BPF_PROG_LOAD"))
258		goto cleanup;
259	nr_map_ids = ARRAY_SIZE(map_ids);
260	if (!check_expected_map_ids(prog_fd, 1, map_ids, &nr_map_ids))
261		goto cleanup;
262
263	/* map should still exist when original file descriptor is closed */
264	Close(extra_fds[0]);
265	if (!ASSERT_EQ(map_exists(map_ids[0]), true, "map should exist"))
266		goto cleanup;
267
268	/* some fds might be invalid, so ignore return codes */
269cleanup:
270	Close(extra_fds[0]);
271	Close(prog_fd);
272}
273
274static int get_btf_id_by_fd(int btf_fd, __u32 *id)
275{
276	struct bpf_btf_info info;
277	__u32 info_len = sizeof(info);
278	int err;
279
280	memset(&info, 0, info_len);
281	err = bpf_btf_get_info_by_fd(btf_fd, &info, &info_len);
282	if (err)
283		return err;
284	if (id)
285		*id = info.id;
286	return 0;
287}
288
289/*
290 * Check that fd_array operates properly for btfs. Namely, to check that
291 * passing a btf fd in fd_array increases its reference count, do the
292 * following:
293 *  1) Create a new btf, it's referenced only by a file descriptor, so refcnt=1
294 *  2) Load a BPF prog with fd_array[0] = btf_fd; now btf's refcnt=2
295 *  3) Close the btf_fd, now refcnt=1
296 * Wait and check that BTF still exists.
297 */
298static void check_fd_array_cnt__referenced_btfs(void)
299{
300	int extra_fds[1] = { -1 };
301	int prog_fd = -1;
302	__u32 btf_id;
303	int tries;
304	int err;
305
306	extra_fds[0] = new_btf();
307	if (!ASSERT_GE(extra_fds[0], 0, "new_btf"))
308		goto cleanup;
309	prog_fd = load_test_prog(extra_fds, 1);
310	if (!ASSERT_GE(prog_fd, 0, "BPF_PROG_LOAD"))
311		goto cleanup;
312
313	/* btf should still exist when original file descriptor is closed */
314	err = get_btf_id_by_fd(extra_fds[0], &btf_id);
315	if (!ASSERT_EQ(err, 0, "get_btf_id_by_fd"))
316		goto cleanup;
317
318	Close(extra_fds[0]);
319
320	if (!ASSERT_GE(kern_sync_rcu(), 0, "kern_sync_rcu 1"))
321		goto cleanup;
322
323	if (!ASSERT_EQ(btf_exists(btf_id), true, "btf should exist"))
324		goto cleanup;
325
326	Close(prog_fd);
327
328	/* The program is freed by a workqueue, so no reliable
329	 * way to sync, so just wait a bit (max ~1 second). */
330	for (tries = 100; tries >= 0; tries--) {
331		usleep(1000);
332
333		if (!btf_exists(btf_id))
334			break;
335
336		if (tries)
337			continue;
338
339		PRINT_FAIL("btf should have been freed");
340	}
341
342	/* some fds might be invalid, so ignore return codes */
343cleanup:
344	Close(extra_fds[0]);
345	Close(prog_fd);
346}
347
348/*
349 * Test that a program with trash in fd_array can't be loaded:
350 * only map and BTF file descriptors should be accepted.
351 */
352static void check_fd_array_cnt__fd_array_with_trash(void)
353{
354	int extra_fds[3] = { -1, -1, -1 };
355	int prog_fd = -1;
356
357	extra_fds[0] = new_map();
358	if (!ASSERT_GE(extra_fds[0], 0, "new_map"))
359		goto cleanup;
360	extra_fds[1] = new_btf();
361	if (!ASSERT_GE(extra_fds[1], 0, "new_btf"))
362		goto cleanup;
363
364	/* trash 1: not a file descriptor */
365	extra_fds[2] = 0xbeef;
366	prog_fd = load_test_prog(extra_fds, 3);
367	if (!ASSERT_EQ(prog_fd, -EBADF, "prog should have been rejected with -EBADF"))
368		goto cleanup;
369
370	/* trash 2: not a map or btf */
371	extra_fds[2] = socket(AF_INET, SOCK_STREAM, 0);
372	if (!ASSERT_GE(extra_fds[2], 0, "socket"))
373		goto cleanup;
374
375	prog_fd = load_test_prog(extra_fds, 3);
376	if (!ASSERT_EQ(prog_fd, -EINVAL, "prog should have been rejected with -EINVAL"))
377		goto cleanup;
378
379	/* Validate that the prog is ok if trash is removed */
380	Close(extra_fds[2]);
381	extra_fds[2] = new_btf();
382	if (!ASSERT_GE(extra_fds[2], 0, "new_btf"))
383		goto cleanup;
384
385	prog_fd = load_test_prog(extra_fds, 3);
386	if (!ASSERT_GE(prog_fd, 0, "prog should have been loaded"))
387		goto cleanup;
388
389	/* some fds might be invalid, so ignore return codes */
390cleanup:
391	Close(extra_fds[2]);
392	Close(extra_fds[1]);
393	Close(extra_fds[0]);
394}
395
396/*
397 * Test that a program with too big fd_array can't be loaded.
398 */
399static void check_fd_array_cnt__fd_array_too_big(void)
400{
401	int extra_fds[65];
402	int prog_fd = -1;
403	int i;
404
405	for (i = 0; i < 65; i++) {
406		extra_fds[i] = new_map();
407		if (!ASSERT_GE(extra_fds[i], 0, "new_map"))
408			goto cleanup_fds;
409	}
410
411	prog_fd = load_test_prog(extra_fds, 65);
412	ASSERT_EQ(prog_fd, -E2BIG, "prog should have been rejected with -E2BIG");
413
414cleanup_fds:
415	while (i > 0)
416		Close(extra_fds[--i]);
417}
418
419void test_fd_array_cnt(void)
420{
421	if (test__start_subtest("no-fd-array"))
422		check_fd_array_cnt__no_fd_array();
423
424	if (test__start_subtest("fd-array-ok"))
425		check_fd_array_cnt__fd_array_ok();
426
427	if (test__start_subtest("fd-array-dup-input"))
428		check_fd_array_cnt__duplicated_maps();
429
430	if (test__start_subtest("fd-array-ref-maps-in-array"))
431		check_fd_array_cnt__referenced_maps_in_fd_array();
432
433	if (test__start_subtest("fd-array-ref-btfs"))
434		check_fd_array_cnt__referenced_btfs();
435
436	if (test__start_subtest("fd-array-trash-input"))
437		check_fd_array_cnt__fd_array_with_trash();
438
439	if (test__start_subtest("fd-array-2big"))
440		check_fd_array_cnt__fd_array_too_big();
441}