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// SPDX-License-Identifier: GPL-2.0
#include <linux/limits.h>
#include <signal.h>
#include "../kselftest.h"
#include "cgroup_util.h"
static int idle_process_fn(const char *cgroup, void *arg)
{
(void)pause();
return 0;
}
static int do_migration_fn(const char *cgroup, void *arg)
{
int object_pid = (int)(size_t)arg;
if (setuid(TEST_UID))
return EXIT_FAILURE;
// XXX checking /proc/$pid/cgroup would be quicker than wait
if (cg_enter(cgroup, object_pid) ||
cg_wait_for_proc_count(cgroup, 1))
return EXIT_FAILURE;
return EXIT_SUCCESS;
}
static int do_controller_fn(const char *cgroup, void *arg)
{
const char *child = cgroup;
const char *parent = arg;
if (setuid(TEST_UID))
return EXIT_FAILURE;
if (!cg_read_strstr(child, "cgroup.controllers", "cpuset"))
return EXIT_FAILURE;
if (cg_write(parent, "cgroup.subtree_control", "+cpuset"))
return EXIT_FAILURE;
if (cg_read_strstr(child, "cgroup.controllers", "cpuset"))
return EXIT_FAILURE;
if (cg_write(parent, "cgroup.subtree_control", "-cpuset"))
return EXIT_FAILURE;
if (!cg_read_strstr(child, "cgroup.controllers", "cpuset"))
return EXIT_FAILURE;
return EXIT_SUCCESS;
}
/*
* Migrate a process between two sibling cgroups.
* The success should only depend on the parent cgroup permissions and not the
* migrated process itself (cpuset controller is in place because it uses
* security_task_setscheduler() in cgroup v1).
*
* Deliberately don't set cpuset.cpus in children to avoid definining migration
* permissions between two different cpusets.
*/
static int test_cpuset_perms_object(const char *root, bool allow)
{
char *parent = NULL, *child_src = NULL, *child_dst = NULL;
char *parent_procs = NULL, *child_src_procs = NULL, *child_dst_procs = NULL;
const uid_t test_euid = TEST_UID;
int object_pid = 0;
int ret = KSFT_FAIL;
parent = cg_name(root, "cpuset_test_0");
if (!parent)
goto cleanup;
parent_procs = cg_name(parent, "cgroup.procs");
if (!parent_procs)
goto cleanup;
if (cg_create(parent))
goto cleanup;
child_src = cg_name(parent, "cpuset_test_1");
if (!child_src)
goto cleanup;
child_src_procs = cg_name(child_src, "cgroup.procs");
if (!child_src_procs)
goto cleanup;
if (cg_create(child_src))
goto cleanup;
child_dst = cg_name(parent, "cpuset_test_2");
if (!child_dst)
goto cleanup;
child_dst_procs = cg_name(child_dst, "cgroup.procs");
if (!child_dst_procs)
goto cleanup;
if (cg_create(child_dst))
goto cleanup;
if (cg_write(parent, "cgroup.subtree_control", "+cpuset"))
goto cleanup;
if (cg_read_strstr(child_src, "cgroup.controllers", "cpuset") ||
cg_read_strstr(child_dst, "cgroup.controllers", "cpuset"))
goto cleanup;
/* Enable permissions along src->dst tree path */
if (chown(child_src_procs, test_euid, -1) ||
chown(child_dst_procs, test_euid, -1))
goto cleanup;
if (allow && chown(parent_procs, test_euid, -1))
goto cleanup;
/* Fork a privileged child as a test object */
object_pid = cg_run_nowait(child_src, idle_process_fn, NULL);
if (object_pid < 0)
goto cleanup;
/* Carry out migration in a child process that can drop all privileges
* (including capabilities), the main process must remain privileged for
* cleanup.
* Child process's cgroup is irrelevant but we place it into child_dst
* as hacky way to pass information about migration target to the child.
*/
if (allow ^ (cg_run(child_dst, do_migration_fn, (void *)(size_t)object_pid) == EXIT_SUCCESS))
goto cleanup;
ret = KSFT_PASS;
cleanup:
if (object_pid > 0) {
(void)kill(object_pid, SIGTERM);
(void)clone_reap(object_pid, WEXITED);
}
cg_destroy(child_dst);
free(child_dst_procs);
free(child_dst);
cg_destroy(child_src);
free(child_src_procs);
free(child_src);
cg_destroy(parent);
free(parent_procs);
free(parent);
return ret;
}
static int test_cpuset_perms_object_allow(const char *root)
{
return test_cpuset_perms_object(root, true);
}
static int test_cpuset_perms_object_deny(const char *root)
{
return test_cpuset_perms_object(root, false);
}
/*
* Migrate a process between parent and child implicitely
* Implicit migration happens when a controller is enabled/disabled.
*
*/
static int test_cpuset_perms_subtree(const char *root)
{
char *parent = NULL, *child = NULL;
char *parent_procs = NULL, *parent_subctl = NULL, *child_procs = NULL;
const uid_t test_euid = TEST_UID;
int object_pid = 0;
int ret = KSFT_FAIL;
parent = cg_name(root, "cpuset_test_0");
if (!parent)
goto cleanup;
parent_procs = cg_name(parent, "cgroup.procs");
if (!parent_procs)
goto cleanup;
parent_subctl = cg_name(parent, "cgroup.subtree_control");
if (!parent_subctl)
goto cleanup;
if (cg_create(parent))
goto cleanup;
child = cg_name(parent, "cpuset_test_1");
if (!child)
goto cleanup;
child_procs = cg_name(child, "cgroup.procs");
if (!child_procs)
goto cleanup;
if (cg_create(child))
goto cleanup;
/* Enable permissions as in a delegated subtree */
if (chown(parent_procs, test_euid, -1) ||
chown(parent_subctl, test_euid, -1) ||
chown(child_procs, test_euid, -1))
goto cleanup;
/* Put a privileged child in the subtree and modify controller state
* from an unprivileged process, the main process remains privileged
* for cleanup.
* The unprivileged child runs in subtree too to avoid parent and
* internal-node constraing violation.
*/
object_pid = cg_run_nowait(child, idle_process_fn, NULL);
if (object_pid < 0)
goto cleanup;
if (cg_run(child, do_controller_fn, parent) != EXIT_SUCCESS)
goto cleanup;
ret = KSFT_PASS;
cleanup:
if (object_pid > 0) {
(void)kill(object_pid, SIGTERM);
(void)clone_reap(object_pid, WEXITED);
}
cg_destroy(child);
free(child_procs);
free(child);
cg_destroy(parent);
free(parent_subctl);
free(parent_procs);
free(parent);
return ret;
}
#define T(x) { x, #x }
struct cpuset_test {
int (*fn)(const char *root);
const char *name;
} tests[] = {
T(test_cpuset_perms_object_allow),
T(test_cpuset_perms_object_deny),
T(test_cpuset_perms_subtree),
};
#undef T
int main(int argc, char *argv[])
{
char root[PATH_MAX];
int i, ret = EXIT_SUCCESS;
if (cg_find_unified_root(root, sizeof(root)))
ksft_exit_skip("cgroup v2 isn't mounted\n");
if (cg_read_strstr(root, "cgroup.subtree_control", "cpuset"))
if (cg_write(root, "cgroup.subtree_control", "+cpuset"))
ksft_exit_skip("Failed to set cpuset controller\n");
for (i = 0; i < ARRAY_SIZE(tests); i++) {
switch (tests[i].fn(root)) {
case KSFT_PASS:
ksft_test_result_pass("%s\n", tests[i].name);
break;
case KSFT_SKIP:
ksft_test_result_skip("%s\n", tests[i].name);
break;
default:
ret = EXIT_FAILURE;
ksft_test_result_fail("%s\n", tests[i].name);
break;
}
}
return ret;
}
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