selftests/bpf: Test BPF_CGROUP_INET_SOCK_RELEASE

// SPDX-License-Identifier: GPL-2.0

#include <test_progs.h>

#include "udp_limit.skel.h"

#include <sys/types.h>

#include <sys/socket.h>

static int duration;

void test_udp_limit(void)

{

	struct udp_limit *skel;

	int fd1 = -1, fd2 = -1;

	int cgroup_fd;

	cgroup_fd = test__join_cgroup("/udp_limit");

	if (CHECK(cgroup_fd < 0, "cg-join", "errno %d", errno))

		return;

	skel = udp_limit__open_and_load();

	if (CHECK(!skel, "skel-load", "errno %d", errno))

		goto close_cgroup_fd;

	skel->links.sock = bpf_program__attach_cgroup(skel->progs.sock, cgroup_fd);

	skel->links.sock_release = bpf_program__attach_cgroup(skel->progs.sock_release, cgroup_fd);

	if (CHECK(IS_ERR(skel->links.sock) || IS_ERR(skel->links.sock_release),

		  "cg-attach", "sock %ld sock_release %ld",

		  PTR_ERR(skel->links.sock),

		  PTR_ERR(skel->links.sock_release)))

		goto close_skeleton;

	/* BPF program enforces a single UDP socket per cgroup,

	 * verify that.

	 */

	fd1 = socket(AF_INET, SOCK_DGRAM, 0);

	if (CHECK(fd1 < 0, "fd1", "errno %d", errno))

		goto close_skeleton;

	fd2 = socket(AF_INET, SOCK_DGRAM, 0);

	if (CHECK(fd2 >= 0, "fd2", "errno %d", errno))

		goto close_skeleton;

	/* We can reopen again after close. */

	close(fd1);

	fd1 = -1;

	fd1 = socket(AF_INET, SOCK_DGRAM, 0);

	if (CHECK(fd1 < 0, "fd1-again", "errno %d", errno))

		goto close_skeleton;

	/* Make sure the program was invoked the expected

	 * number of times:

	 * - open fd1           - BPF_CGROUP_INET_SOCK_CREATE

	 * - attempt to openfd2 - BPF_CGROUP_INET_SOCK_CREATE

	 * - close fd1          - BPF_CGROUP_INET_SOCK_RELEASE

	 * - open fd1 again     - BPF_CGROUP_INET_SOCK_CREATE

	 */

	if (CHECK(skel->bss->invocations != 4, "bss-invocations",

		  "invocations=%d", skel->bss->invocations))

		goto close_skeleton;

	/* We should still have a single socket in use */

	if (CHECK(skel->bss->in_use != 1, "bss-in_use",

		  "in_use=%d", skel->bss->in_use))

		goto close_skeleton;

close_skeleton:

	if (fd1 >= 0)

		close(fd1);

	if (fd2 >= 0)

		close(fd2);

	udp_limit__destroy(skel);

close_cgroup_fd:

	close(cgroup_fd);

}

// SPDX-License-Identifier: GPL-2.0-only

#include <sys/socket.h>

#include <linux/bpf.h>

#include <bpf/bpf_helpers.h>

int invocations = 0, in_use = 0;

SEC("cgroup/sock_create")

int sock(struct bpf_sock *ctx)

{

	__u32 key;

	if (ctx->type != SOCK_DGRAM)

		return 1;

	__sync_fetch_and_add(&invocations, 1);

	if (in_use > 0) {

		/* BPF_CGROUP_INET_SOCK_RELEASE is _not_ called

		 * when we return an error from the BPF

		 * program!

		 */

		return 0;

	}

	__sync_fetch_and_add(&in_use, 1);

	return 1;

}

SEC("cgroup/sock_release")

int sock_release(struct bpf_sock *ctx)

{

	__u32 key;

	if (ctx->type != SOCK_DGRAM)

		return 1;

	__sync_fetch_and_add(&invocations, 1);

	__sync_fetch_and_add(&in_use, -1);

	return 1;

}