summaryrefslogtreecommitdiff
path: root/tools/testing/selftests/bpf/cgroup_helpers.c
blob: e914cc45b7669eae2b7f5859b90c998f61b7aec4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <sched.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <linux/limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/sched.h>
#include <fcntl.h>
#include <unistd.h>
#include <ftw.h>

#include "cgroup_helpers.h"

/*
 * To avoid relying on the system setup, when setup_cgroup_env is called
 * we create a new mount namespace, and cgroup namespace. The cgroupv2
 * root is mounted at CGROUP_MOUNT_PATH. Unfortunately, most people don't
 * have cgroupv2 enabled at this point in time. It's easier to create our
 * own mount namespace and manage it ourselves. We assume /mnt exists.
 *
 * Related cgroupv1 helpers are named *classid*(), since we only use the
 * net_cls controller for tagging net_cls.classid. We assume the default
 * mount under /sys/fs/cgroup/net_cls, which should be the case for the
 * vast majority of users.
 */

#define WALK_FD_LIMIT			16

#define CGROUP_MOUNT_PATH		"/mnt"
#define CGROUP_MOUNT_DFLT		"/sys/fs/cgroup"
#define NETCLS_MOUNT_PATH		CGROUP_MOUNT_DFLT "/net_cls"
#define CGROUP_WORK_DIR			"/cgroup-test-work-dir"

#define format_cgroup_path_pid(buf, path, pid) \
	snprintf(buf, sizeof(buf), "%s%s%d%s", CGROUP_MOUNT_PATH, \
	CGROUP_WORK_DIR, pid, path)

#define format_cgroup_path(buf, path) \
	format_cgroup_path_pid(buf, path, getpid())

#define format_parent_cgroup_path(buf, path) \
	format_cgroup_path_pid(buf, path, getppid())

#define format_classid_path(buf)				\
	snprintf(buf, sizeof(buf), "%s%s", NETCLS_MOUNT_PATH,	\
		 CGROUP_WORK_DIR)

static int __enable_controllers(const char *cgroup_path, const char *controllers)
{
	char path[PATH_MAX + 1];
	char enable[PATH_MAX + 1];
	char *c, *c2;
	int fd, cfd;
	ssize_t len;

	/* If not controllers are passed, enable all available controllers */
	if (!controllers) {
		snprintf(path, sizeof(path), "%s/cgroup.controllers",
			 cgroup_path);
		fd = open(path, O_RDONLY);
		if (fd < 0) {
			log_err("Opening cgroup.controllers: %s", path);
			return 1;
		}
		len = read(fd, enable, sizeof(enable) - 1);
		if (len < 0) {
			close(fd);
			log_err("Reading cgroup.controllers: %s", path);
			return 1;
		} else if (len == 0) { /* No controllers to enable */
			close(fd);
			return 0;
		}
		enable[len] = 0;
		close(fd);
	} else {
		strncpy(enable, controllers, sizeof(enable));
	}

	snprintf(path, sizeof(path), "%s/cgroup.subtree_control", cgroup_path);
	cfd = open(path, O_RDWR);
	if (cfd < 0) {
		log_err("Opening cgroup.subtree_control: %s", path);
		return 1;
	}

	for (c = strtok_r(enable, " ", &c2); c; c = strtok_r(NULL, " ", &c2)) {
		if (dprintf(cfd, "+%s\n", c) <= 0) {
			log_err("Enabling controller %s: %s", c, path);
			close(cfd);
			return 1;
		}
	}
	close(cfd);
	return 0;
}

/**
 * enable_controllers() - Enable cgroup v2 controllers
 * @relative_path: The cgroup path, relative to the workdir
 * @controllers: List of controllers to enable in cgroup.controllers format
 *
 *
 * Enable given cgroup v2 controllers, if @controllers is NULL, enable all
 * available controllers.
 *
 * If successful, 0 is returned.
 */
int enable_controllers(const char *relative_path, const char *controllers)
{
	char cgroup_path[PATH_MAX + 1];

	format_cgroup_path(cgroup_path, relative_path);
	return __enable_controllers(cgroup_path, controllers);
}

static int __write_cgroup_file(const char *cgroup_path, const char *file,
			       const char *buf)
{
	char file_path[PATH_MAX + 1];
	int fd;

	snprintf(file_path, sizeof(file_path), "%s/%s", cgroup_path, file);
	fd = open(file_path, O_RDWR);
	if (fd < 0) {
		log_err("Opening %s", file_path);
		return 1;
	}

	if (dprintf(fd, "%s", buf) <= 0) {
		log_err("Writing to %s", file_path);
		close(fd);
		return 1;
	}
	close(fd);
	return 0;
}

/**
 * write_cgroup_file() - Write to a cgroup file
 * @relative_path: The cgroup path, relative to the workdir
 * @file: The name of the file in cgroupfs to write to
 * @buf: Buffer to write to the file
 *
 * Write to a file in the given cgroup's directory.
 *
 * If successful, 0 is returned.
 */
int write_cgroup_file(const char *relative_path, const char *file,
		      const char *buf)
{
	char cgroup_path[PATH_MAX - 24];

	format_cgroup_path(cgroup_path, relative_path);
	return __write_cgroup_file(cgroup_path, file, buf);
}

/**
 * write_cgroup_file_parent() - Write to a cgroup file in the parent process
 *                              workdir
 * @relative_path: The cgroup path, relative to the parent process workdir
 * @file: The name of the file in cgroupfs to write to
 * @buf: Buffer to write to the file
 *
 * Write to a file in the given cgroup's directory under the parent process
 * workdir.
 *
 * If successful, 0 is returned.
 */
int write_cgroup_file_parent(const char *relative_path, const char *file,
			     const char *buf)
{
	char cgroup_path[PATH_MAX - 24];

	format_parent_cgroup_path(cgroup_path, relative_path);
	return __write_cgroup_file(cgroup_path, file, buf);
}

/**
 * setup_cgroup_environment() - Setup the cgroup environment
 *
 * After calling this function, cleanup_cgroup_environment should be called
 * once testing is complete.
 *
 * This function will print an error to stderr and return 1 if it is unable
 * to setup the cgroup environment. If setup is successful, 0 is returned.
 */
int setup_cgroup_environment(void)
{
	char cgroup_workdir[PATH_MAX - 24];

	format_cgroup_path(cgroup_workdir, "");

	if (unshare(CLONE_NEWNS)) {
		log_err("unshare");
		return 1;
	}

	if (mount("none", "/", NULL, MS_REC | MS_PRIVATE, NULL)) {
		log_err("mount fakeroot");
		return 1;
	}

	if (mount("none", CGROUP_MOUNT_PATH, "cgroup2", 0, NULL) && errno != EBUSY) {
		log_err("mount cgroup2");
		return 1;
	}

	/* Cleanup existing failed runs, now that the environment is setup */
	cleanup_cgroup_environment();

	if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) {
		log_err("mkdir cgroup work dir");
		return 1;
	}

	/* Enable all available controllers to increase test coverage */
	if (__enable_controllers(CGROUP_MOUNT_PATH, NULL) ||
	    __enable_controllers(cgroup_workdir, NULL))
		return 1;

	return 0;
}

static int nftwfunc(const char *filename, const struct stat *statptr,
		    int fileflags, struct FTW *pfwt)
{
	if ((fileflags & FTW_D) && rmdir(filename))
		log_err("Removing cgroup: %s", filename);
	return 0;
}

static int join_cgroup_from_top(const char *cgroup_path)
{
	char cgroup_procs_path[PATH_MAX + 1];
	pid_t pid = getpid();
	int fd, rc = 0;

	snprintf(cgroup_procs_path, sizeof(cgroup_procs_path),
		 "%s/cgroup.procs", cgroup_path);

	fd = open(cgroup_procs_path, O_WRONLY);
	if (fd < 0) {
		log_err("Opening Cgroup Procs: %s", cgroup_procs_path);
		return 1;
	}

	if (dprintf(fd, "%d\n", pid) < 0) {
		log_err("Joining Cgroup");
		rc = 1;
	}

	close(fd);
	return rc;
}

/**
 * join_cgroup() - Join a cgroup
 * @relative_path: The cgroup path, relative to the workdir, to join
 *
 * This function expects a cgroup to already be created, relative to the cgroup
 * work dir, and it joins it. For example, passing "/my-cgroup" as the path
 * would actually put the calling process into the cgroup
 * "/cgroup-test-work-dir/my-cgroup"
 *
 * On success, it returns 0, otherwise on failure it returns 1.
 */
int join_cgroup(const char *relative_path)
{
	char cgroup_path[PATH_MAX + 1];

	format_cgroup_path(cgroup_path, relative_path);
	return join_cgroup_from_top(cgroup_path);
}

/**
 * join_parent_cgroup() - Join a cgroup in the parent process workdir
 * @relative_path: The cgroup path, relative to parent process workdir, to join
 *
 * See join_cgroup().
 *
 * On success, it returns 0, otherwise on failure it returns 1.
 */
int join_parent_cgroup(const char *relative_path)
{
	char cgroup_path[PATH_MAX + 1];

	format_parent_cgroup_path(cgroup_path, relative_path);
	return join_cgroup_from_top(cgroup_path);
}

/**
 * cleanup_cgroup_environment() - Cleanup Cgroup Testing Environment
 *
 * This is an idempotent function to delete all temporary cgroups that
 * have been created during the test, including the cgroup testing work
 * directory.
 *
 * At call time, it moves the calling process to the root cgroup, and then
 * runs the deletion process. It is idempotent, and should not fail, unless
 * a process is lingering.
 *
 * On failure, it will print an error to stderr, and try to continue.
 */
void cleanup_cgroup_environment(void)
{
	char cgroup_workdir[PATH_MAX + 1];

	format_cgroup_path(cgroup_workdir, "");
	join_cgroup_from_top(CGROUP_MOUNT_PATH);
	nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT);
}

/**
 * get_root_cgroup() - Get the FD of the root cgroup
 *
 * On success, it returns the file descriptor. On failure, it returns -1.
 * If there is a failure, it prints the error to stderr.
 */
int get_root_cgroup(void)
{
	int fd;

	fd = open(CGROUP_MOUNT_PATH, O_RDONLY);
	if (fd < 0) {
		log_err("Opening root cgroup");
		return -1;
	}
	return fd;
}

/**
 * create_and_get_cgroup() - Create a cgroup, relative to workdir, and get the FD
 * @relative_path: The cgroup path, relative to the workdir, to join
 *
 * This function creates a cgroup under the top level workdir and returns the
 * file descriptor. It is idempotent.
 *
 * On success, it returns the file descriptor. On failure it returns -1.
 * If there is a failure, it prints the error to stderr.
 */
int create_and_get_cgroup(const char *relative_path)
{
	char cgroup_path[PATH_MAX + 1];
	int fd;

	format_cgroup_path(cgroup_path, relative_path);
	if (mkdir(cgroup_path, 0777) && errno != EEXIST) {
		log_err("mkdiring cgroup %s .. %s", relative_path, cgroup_path);
		return -1;
	}

	fd = open(cgroup_path, O_RDONLY);
	if (fd < 0) {
		log_err("Opening Cgroup");
		return -1;
	}

	return fd;
}

/**
 * get_cgroup_id() - Get cgroup id for a particular cgroup path
 * @relative_path: The cgroup path, relative to the workdir, to join
 *
 * On success, it returns the cgroup id. On failure it returns 0,
 * which is an invalid cgroup id.
 * If there is a failure, it prints the error to stderr.
 */
unsigned long long get_cgroup_id(const char *relative_path)
{
	int dirfd, err, flags, mount_id, fhsize;
	union {
		unsigned long long cgid;
		unsigned char raw_bytes[8];
	} id;
	char cgroup_workdir[PATH_MAX + 1];
	struct file_handle *fhp, *fhp2;
	unsigned long long ret = 0;

	format_cgroup_path(cgroup_workdir, relative_path);

	dirfd = AT_FDCWD;
	flags = 0;
	fhsize = sizeof(*fhp);
	fhp = calloc(1, fhsize);
	if (!fhp) {
		log_err("calloc");
		return 0;
	}
	err = name_to_handle_at(dirfd, cgroup_workdir, fhp, &mount_id, flags);
	if (err >= 0 || fhp->handle_bytes != 8) {
		log_err("name_to_handle_at");
		goto free_mem;
	}

	fhsize = sizeof(struct file_handle) + fhp->handle_bytes;
	fhp2 = realloc(fhp, fhsize);
	if (!fhp2) {
		log_err("realloc");
		goto free_mem;
	}
	err = name_to_handle_at(dirfd, cgroup_workdir, fhp2, &mount_id, flags);
	fhp = fhp2;
	if (err < 0) {
		log_err("name_to_handle_at");
		goto free_mem;
	}

	memcpy(id.raw_bytes, fhp->f_handle, 8);
	ret = id.cgid;

free_mem:
	free(fhp);
	return ret;
}

int cgroup_setup_and_join(const char *path) {
	int cg_fd;

	if (setup_cgroup_environment()) {
		fprintf(stderr, "Failed to setup cgroup environment\n");
		return -EINVAL;
	}

	cg_fd = create_and_get_cgroup(path);
	if (cg_fd < 0) {
		fprintf(stderr, "Failed to create test cgroup\n");
		cleanup_cgroup_environment();
		return cg_fd;
	}

	if (join_cgroup(path)) {
		fprintf(stderr, "Failed to join cgroup\n");
		cleanup_cgroup_environment();
		return -EINVAL;
	}
	return cg_fd;
}

/**
 * setup_classid_environment() - Setup the cgroupv1 net_cls environment
 *
 * After calling this function, cleanup_classid_environment should be called
 * once testing is complete.
 *
 * This function will print an error to stderr and return 1 if it is unable
 * to setup the cgroup environment. If setup is successful, 0 is returned.
 */
int setup_classid_environment(void)
{
	char cgroup_workdir[PATH_MAX + 1];

	format_classid_path(cgroup_workdir);

	if (mount("tmpfs", CGROUP_MOUNT_DFLT, "tmpfs", 0, NULL) &&
	    errno != EBUSY) {
		log_err("mount cgroup base");
		return 1;
	}

	if (mkdir(NETCLS_MOUNT_PATH, 0777) && errno != EEXIST) {
		log_err("mkdir cgroup net_cls");
		return 1;
	}

	if (mount("net_cls", NETCLS_MOUNT_PATH, "cgroup", 0, "net_cls") &&
	    errno != EBUSY) {
		log_err("mount cgroup net_cls");
		return 1;
	}

	cleanup_classid_environment();

	if (mkdir(cgroup_workdir, 0777) && errno != EEXIST) {
		log_err("mkdir cgroup work dir");
		return 1;
	}

	return 0;
}

/**
 * set_classid() - Set a cgroupv1 net_cls classid
 * @id: the numeric classid
 *
 * Writes the passed classid into the cgroup work dir's net_cls.classid
 * file in order to later on trigger socket tagging.
 *
 * On success, it returns 0, otherwise on failure it returns 1. If there
 * is a failure, it prints the error to stderr.
 */
int set_classid(unsigned int id)
{
	char cgroup_workdir[PATH_MAX - 42];
	char cgroup_classid_path[PATH_MAX + 1];
	int fd, rc = 0;

	format_classid_path(cgroup_workdir);
	snprintf(cgroup_classid_path, sizeof(cgroup_classid_path),
		 "%s/net_cls.classid", cgroup_workdir);

	fd = open(cgroup_classid_path, O_WRONLY);
	if (fd < 0) {
		log_err("Opening cgroup classid: %s", cgroup_classid_path);
		return 1;
	}

	if (dprintf(fd, "%u\n", id) < 0) {
		log_err("Setting cgroup classid");
		rc = 1;
	}

	close(fd);
	return rc;
}

/**
 * join_classid() - Join a cgroupv1 net_cls classid
 *
 * This function expects the cgroup work dir to be already created, as we
 * join it here. This causes the process sockets to be tagged with the given
 * net_cls classid.
 *
 * On success, it returns 0, otherwise on failure it returns 1.
 */
int join_classid(void)
{
	char cgroup_workdir[PATH_MAX + 1];

	format_classid_path(cgroup_workdir);
	return join_cgroup_from_top(cgroup_workdir);
}

/**
 * cleanup_classid_environment() - Cleanup the cgroupv1 net_cls environment
 *
 * At call time, it moves the calling process to the root cgroup, and then
 * runs the deletion process.
 *
 * On failure, it will print an error to stderr, and try to continue.
 */
void cleanup_classid_environment(void)
{
	char cgroup_workdir[PATH_MAX + 1];

	format_classid_path(cgroup_workdir);
	join_cgroup_from_top(NETCLS_MOUNT_PATH);
	nftw(cgroup_workdir, nftwfunc, WALK_FD_LIMIT, FTW_DEPTH | FTW_MOUNT);
}