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// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <linux/cgroupstats.h>
#include <linux/genetlink.h>
#include <linux/netlink.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include "netlink_helper.h"
#include "kselftest.h"
static int send_cgroupstats_cmd(int fd, int family_id, uint32_t cgroup_fd,
int flags)
{
struct {
struct nlmsghdr nlh;
struct genlmsghdr genl;
char buf[256];
} req = { 0 };
struct nlattr *na;
req.nlh.nlmsg_len = NLMSG_LENGTH(GENL_HDRLEN);
req.nlh.nlmsg_type = family_id;
req.nlh.nlmsg_flags = NLM_F_REQUEST | flags;
req.nlh.nlmsg_seq = 2;
req.nlh.nlmsg_pid = getpid();
req.genl.cmd = CGROUPSTATS_CMD_GET;
req.genl.version = 1;
na = (struct nlattr *)((char *)&req + NLMSG_ALIGN(req.nlh.nlmsg_len));
na->nla_type = CGROUPSTATS_CMD_ATTR_FD;
na->nla_len = NLA_HDRLEN + sizeof(cgroup_fd);
memcpy(nla_data(na), &cgroup_fd, sizeof(cgroup_fd));
req.nlh.nlmsg_len = NLMSG_ALIGN(req.nlh.nlmsg_len) + NLA_ALIGN(na->nla_len);
return send_request(fd, &req, req.nlh.nlmsg_len);
}
/*
* Receive and decode a cgroupstats response.
*
* Returns:
* 0 — success, stats filled from CGROUPSTATS_CMD_NEW reply
* <0 — NLMSG_ERROR errno (e.g. -EBADF, -EINVAL)
*/
static int recv_cgroupstats_response(int fd, struct cgroupstats *stats)
{
char resp[8192];
struct nlmsghdr *nlh;
struct genlmsghdr *genl;
struct nlattr *na;
int len;
int rem;
memset(stats, 0, sizeof(*stats));
len = recv(fd, resp, sizeof(resp), 0);
if (len < 0)
return -errno;
for (nlh = (struct nlmsghdr *)resp; NLMSG_OK(nlh, len);
nlh = NLMSG_NEXT(nlh, len)) {
if (nlh->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err = NLMSG_DATA(nlh);
return err->error;
}
genl = (struct genlmsghdr *)NLMSG_DATA(nlh);
if (genl->cmd != CGROUPSTATS_CMD_NEW)
continue;
rem = nlh->nlmsg_len - NLMSG_HDRLEN - GENL_HDRLEN;
na = (struct nlattr *)((char *)genl + GENL_HDRLEN);
while (nla_ok(na, rem)) {
if (na->nla_type == CGROUPSTATS_TYPE_CGROUP_STATS) {
memcpy(stats, nla_data(na), sizeof(*stats));
return 0;
}
na = nla_next(na, &rem);
}
}
return -EIO;
}
/* mkdtemp() modifies the template in place, so this cannot be const. */
static char cg_mountpoint[32];
static bool cg_mounted;
static int setup_cgroup_v1(void)
{
strcpy(cg_mountpoint, "/tmp/cgstats_test_XXXXXX");
if (!mkdtemp(cg_mountpoint))
return -errno;
if (mount("cgstats_test", cg_mountpoint, "cgroup", 0,
"none,name=cgstats_test") < 0) {
int ret = -errno;
rmdir(cg_mountpoint);
return ret;
}
cg_mounted = true;
return 0;
}
static void cleanup_cgroup_v1(void)
{
if (!cg_mounted)
return;
umount2(cg_mountpoint, MNT_DETACH);
rmdir(cg_mountpoint);
cg_mounted = false;
}
int main(void)
{
struct cgroupstats stats;
uint64_t total_tasks;
int family_id;
int nl_fd;
int cg_fd;
int ret;
ksft_print_header();
nl_fd = netlink_open();
if (nl_fd < 0)
ksft_exit_skip("failed to open generic netlink socket: %s\n",
strerror(-nl_fd));
family_id = get_family_id(nl_fd, TASKSTATS_GENL_NAME);
if (family_id < 0)
ksft_exit_skip("taskstats generic netlink family unavailable: %s\n",
strerror(-family_id));
ksft_set_plan(3);
/*
* Test 1: mount a private cgroup v1 hierarchy, query it, and
* verify the response contains sane task counts. If the test
* environment cannot create a private cgroup v1 mount, skip this
* case and continue with the unprivileged regression checks below.
*/
ret = setup_cgroup_v1();
if (ret) {
ksft_test_result_skip("cgroupstats query: cannot mount cgroup v1: %s\n",
strerror(-ret));
} else {
cg_fd = open(cg_mountpoint, O_RDONLY | O_DIRECTORY);
if (cg_fd < 0) {
ksft_test_result_fail("cgroupstats query: open mountpoint: %s\n",
strerror(errno));
} else {
ret = send_cgroupstats_cmd(nl_fd, family_id,
(uint32_t)cg_fd, 0);
if (ret) {
ksft_test_result_fail("cgroupstats query: send: %s\n",
strerror(-ret));
} else {
ret = recv_cgroupstats_response(nl_fd, &stats);
if (ret < 0) {
ksft_test_result_fail("cgroupstats query: %s\n",
strerror(-ret));
} else {
total_tasks = (uint64_t)stats.nr_sleeping +
(uint64_t)stats.nr_running +
(uint64_t)stats.nr_stopped +
(uint64_t)stats.nr_uninterruptible +
(uint64_t)stats.nr_io_wait;
ksft_print_msg("cgroupstats query: total_tasks=%llu\n",
(unsigned long long)total_tasks);
ksft_test_result(total_tasks > 0,
"cgroupstats query returns valid stats\n");
}
}
close(cg_fd);
}
}
cleanup_cgroup_v1();
/*
* Test 2: invalid fd without NLM_F_ACK. The kernel should
* return -EBADF via NLMSG_ERROR regardless of whether the
* client requested an explicit ACK.
*/
ret = send_cgroupstats_cmd(nl_fd, family_id, 0xFFFFFFFF, 0);
if (ret)
ksft_exit_fail_msg("send test 2 failed: %s\n", strerror(-ret));
ret = recv_cgroupstats_response(nl_fd, &stats);
ksft_print_msg("bad fd (no ACK): response=%d (%s)\n",
ret, ret < 0 ? strerror(-ret) : "unexpected success");
ksft_test_result(ret == -EBADF,
"cgroupstats rejects bad fd without NLM_F_ACK\n");
/*
* Test 3: invalid fd with NLM_F_ACK. Same expectation as
* test 2, but exercised through a different netlink flag
* path in the kernel's ack/error handling.
*/
ret = send_cgroupstats_cmd(nl_fd, family_id, 0xFFFFFFFF, NLM_F_ACK);
if (ret)
ksft_exit_fail_msg("send test 3 failed: %s\n", strerror(-ret));
ret = recv_cgroupstats_response(nl_fd, &stats);
ksft_print_msg("bad fd (with ACK): response=%d (%s)\n",
ret, ret < 0 ? strerror(-ret) : "unexpected success");
ksft_test_result(ret == -EBADF,
"cgroupstats rejects bad fd with NLM_F_ACK\n");
close(nl_fd);
ksft_finished();
return ksft_get_fail_cnt() ? KSFT_FAIL : KSFT_PASS;
}
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