[LTP] [PATCH v4 3/3] cgroup_core01: copy from kernel selftest test_cgcore_lesser_euid_open

[Yang Xu <xuyang2018.jy@fujitsu.com>]

Reviewed-by: Richard Palethorpe <rpalethorpe@suse.com>
Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
---
 runtest/controllers                           |   1 +
 .../kernel/controllers/cgroup/.gitignore      |   1 +
 .../kernel/controllers/cgroup/cgroup_core01.c | 107 ++++++++++++++++++
 3 files changed, 109 insertions(+)
 create mode 100644 testcases/kernel/controllers/cgroup/cgroup_core01.c

diff --git a/runtest/controllers b/runtest/controllers
index 22d482050..41f8367e4 100644
--- a/runtest/controllers
+++ b/runtest/controllers
@@ -1,4 +1,5 @@
 #DESCRIPTION:Resource Management testing
+cgroup_core01	cgroup_core01
 cgroup		cgroup_regression_test.sh
 memcg_regression	memcg_regression_test.sh
 memcg_test_3	memcg_test_3
diff --git a/testcases/kernel/controllers/cgroup/.gitignore b/testcases/kernel/controllers/cgroup/.gitignore
index eb91cc4e1..382f2d9f2 100644
--- a/testcases/kernel/controllers/cgroup/.gitignore
+++ b/testcases/kernel/controllers/cgroup/.gitignore
@@ -1,3 +1,4 @@
 /cgroup_regression_fork_processes
 /cgroup_regression_getdelays
 /cgroup_regression_6_2
+/cgroup_core01
diff --git a/testcases/kernel/controllers/cgroup/cgroup_core01.c b/testcases/kernel/controllers/cgroup/cgroup_core01.c
new file mode 100644
index 000000000..fc60ae5aa
--- /dev/null
+++ b/testcases/kernel/controllers/cgroup/cgroup_core01.c
@@ -0,0 +1,107 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022 FUJITSU LIMITED. All rights reserved.
+ * Author: Yang Xu <xuyang2018.jy@cn.fujitsu.com>
+ */
+
+/*\
+ * [Description]
+ *
+ * When a task is writing to an fd opened by a different task, the perm check
+ * should use the credentials of the latter task.
+ *
+ * It is copy from kernel selftests cgroup test_core test_cgcore_lesser_euid_open
+ * subcase. The difference is that kernel selftest only supports cgroup v2 but
+ * here we also support cgroup v1 and v2.
+ *
+ * It is a regression test for
+ *
+ * commit e57457641613fef0d147ede8bd6a3047df588b95
+ * Author: Tejun Heo <tj@kernel.org>
+ * Date:   Thu Jan 6 11:02:29 2022 -1000
+ *
+ * cgroup: Use open-time cgroup namespace for process migration perm checks
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <pwd.h>
+#include "tst_test.h"
+#include "tst_safe_file_at.h"
+
+static struct tst_cg_group *cg_child_a, *cg_child_b;
+static uid_t nobody_uid, save_uid;
+
+static void test_lesser_euid_open(void)
+{
+	int fds[TST_CG_ROOTS_MAX] = {-1};
+	int i, loops;
+
+	cg_child_a = tst_cg_group_mk(tst_cg, "child_a");
+	cg_child_b = tst_cg_group_mk(tst_cg, "child_b");
+
+	if (!SAFE_FORK()) {
+		SAFE_CG_PRINT(cg_child_a, "cgroup.procs", "0");
+		SAFE_CG_FCHOWN(cg_child_a, "cgroup.procs",  nobody_uid, -1);
+		SAFE_CG_FCHOWN(cg_child_b, "cgroup.procs",  nobody_uid, -1);
+		SAFE_SETEUID(nobody_uid);
+
+		loops = SAFE_CG_OPEN(cg_child_b, "cgroup.procs", O_RDWR, fds);
+		SAFE_SETEUID(save_uid);
+
+		for (i = 0; i < loops; i++) {
+			if (fds[i] < 1) {
+				tst_res(TFAIL, "unexpected negative fd %d", fds[i]);
+				exit(1);
+			}
+
+			TEST(write(fds[i], "0", 1));
+			if (TST_RET >= 0 || TST_ERR != EACCES)
+				tst_res(TFAIL, "%s failed", __func__);
+			else
+				tst_res(TPASS | TTERRNO, "%s passed", __func__);
+
+			SAFE_CLOSE(fds[i]);
+		}
+		exit(0);
+	}
+
+	tst_reap_children();
+	cg_child_b = tst_cg_group_rm(cg_child_b);
+	cg_child_a = tst_cg_group_rm(cg_child_a);
+}
+
+static void setup(void)
+{
+	struct passwd *pw;
+
+	pw = SAFE_GETPWNAM("nobody");
+	nobody_uid = pw->pw_uid;
+	save_uid = geteuid();
+}
+
+static void cleanup(void)
+{
+	if (cg_child_a) {
+		SAFE_CG_PRINTF(tst_cg_drain, "cgroup.procs", "%d", getpid());
+		cg_child_a = tst_cg_group_rm(cg_child_a);
+	}
+	if (cg_child_b) {
+		SAFE_CG_PRINTF(tst_cg_drain, "cgroup.procs", "%d", getpid());
+		cg_child_b = tst_cg_group_rm(cg_child_b);
+	}
+}
+
+static struct tst_test test = {
+	.setup = setup,
+	.cleanup = cleanup,
+	.test_all = test_lesser_euid_open,
+	.forks_child = 1,
+	.needs_root = 1,
+	.needs_cgroup_ctrls = (const char *const[]){"memory",  NULL},
+	.tags = (const struct tst_tag[]) {
+		{"linux-git", "e57457641613"},
+		{}
+	},
+};
-- 
2.27.0


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