Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 598a22a0 authored by Tejun Heo's avatar Tejun Heo Committed by Greg Kroah-Hartman
Browse files

selftests: cgroup: Test open-time cgroup namespace usage for migration checks 



commit bf35a7879f1dfb0d050fe779168bcf25c7de66f5 upstream.

When a task is writing to an fd opened by a different task, the perm check
should use the cgroup namespace of the latter task. Add a test for it.

Tested-by: default avatarMichal Koutný <mkoutny@suse.com>
Signed-off-by: default avatarTejun Heo <tj@kernel.org>
[OP: backport to v5.4: adjust context, add wait.h and fcntl.h includes]
Signed-off-by: default avatarOvidiu Panait <ovidiu.panait@windriver.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a3f6c594

tools/testing/selftests/cgroup/test_core.c

+99 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */



#define _GNU_SOURCE

#include <linux/limits.h>

#include <linux/sched.h>

#include <sys/types.h>

#include <sys/wait.h>

#include <unistd.h>

#include <fcntl.h>

#include <sched.h>

#include <stdio.h>

#include <errno.h>
@@ -421,6 +426,99 @@ static int test_cgcore_lesser_euid_open(const char *root) 
	return ret;

}



struct lesser_ns_open_thread_arg {

	const char	*path;

	int		fd;

	int		err;

};



static int lesser_ns_open_thread_fn(void *arg)

{

	struct lesser_ns_open_thread_arg *targ = arg;



	targ->fd = open(targ->path, O_RDWR);

	targ->err = errno;

	return 0;

}



/*

 * cgroup migration permission check should be performed based on the cgroup

 * namespace at the time of open instead of write.

 */

static int test_cgcore_lesser_ns_open(const char *root)

{

	static char stack[65536];

	const uid_t test_euid = 65534;	/* usually nobody, any !root is fine */

	int ret = KSFT_FAIL;

	char *cg_test_a = NULL, *cg_test_b = NULL;

	char *cg_test_a_procs = NULL, *cg_test_b_procs = NULL;

	int cg_test_b_procs_fd = -1;

	struct lesser_ns_open_thread_arg targ = { .fd = -1 };

	pid_t pid;

	int status;



	cg_test_a = cg_name(root, "cg_test_a");

	cg_test_b = cg_name(root, "cg_test_b");



	if (!cg_test_a || !cg_test_b)

		goto cleanup;



	cg_test_a_procs = cg_name(cg_test_a, "cgroup.procs");

	cg_test_b_procs = cg_name(cg_test_b, "cgroup.procs");



	if (!cg_test_a_procs || !cg_test_b_procs)

		goto cleanup;



	if (cg_create(cg_test_a) || cg_create(cg_test_b))

		goto cleanup;



	if (cg_enter_current(cg_test_b))

		goto cleanup;



	if (chown(cg_test_a_procs, test_euid, -1) ||

	    chown(cg_test_b_procs, test_euid, -1))

		goto cleanup;



	targ.path = cg_test_b_procs;

	pid = clone(lesser_ns_open_thread_fn, stack + sizeof(stack),

		    CLONE_NEWCGROUP | CLONE_FILES | CLONE_VM | SIGCHLD,

		    &targ);

	if (pid < 0)

		goto cleanup;



	if (waitpid(pid, &status, 0) < 0)

		goto cleanup;



	if (!WIFEXITED(status))

		goto cleanup;



	cg_test_b_procs_fd = targ.fd;

	if (cg_test_b_procs_fd < 0)

		goto cleanup;



	if (cg_enter_current(cg_test_a))

		goto cleanup;



	if ((status = write(cg_test_b_procs_fd, "0", 1)) >= 0 || errno != ENOENT)

		goto cleanup;



	ret = KSFT_PASS;



cleanup:

	cg_enter_current(root);

	if (cg_test_b_procs_fd >= 0)

		close(cg_test_b_procs_fd);

	if (cg_test_b)

		cg_destroy(cg_test_b);

	if (cg_test_a)

		cg_destroy(cg_test_a);

	free(cg_test_b_procs);

	free(cg_test_a_procs);

	free(cg_test_b);

	free(cg_test_a);

	return ret;

}



#define T(x) { x, #x }

struct corecg_test {

	int (*fn)(const char *root);
@@ -434,6 +532,7 @@ struct corecg_test { 
	T(test_cgcore_invalid_domain),

	T(test_cgcore_populated),

	T(test_cgcore_lesser_euid_open),

	T(test_cgcore_lesser_ns_open),

};

#undef T