From 77f67973f20353fe0759c3135afe69c74d239b44 Mon Sep 17 00:00:00 2001
From: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Date: Wed, 12 Jan 2022 19:30:07 +0300
Subject: [PATCH] zdtm: add mntns_pivot_root test

This creates nested mntns and does pivot_root to tmpfs mount, so that
roots of original test mntns and in nested mntns are different.

Before allowing nested mntnses with different roots in previous patch
this would fail.

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
---
 test/zdtm/static/Makefile              |   1 +
 test/zdtm/static/mntns_pivot_root.c    | 150 +++++++++++++++++++++++++
 test/zdtm/static/mntns_pivot_root.desc |   1 +
 3 files changed, 152 insertions(+)
 create mode 100644 test/zdtm/static/mntns_pivot_root.c
 create mode 100644 test/zdtm/static/mntns_pivot_root.desc

diff --git a/test/zdtm/static/Makefile b/test/zdtm/static/Makefile
index 565b32400..a22a0540f 100644
--- a/test/zdtm/static/Makefile
+++ b/test/zdtm/static/Makefile
@@ -401,6 +401,7 @@ TST_DIR		=				\
 		mnt_ext_dev			\
 		mnt_ext_root			\
 		mnt_ext_collision		\
+		mntns_pivot_root		\
 		mnt_tracefs			\
 		mntns_deleted			\
 		unlink_regular00		\
diff --git a/test/zdtm/static/mntns_pivot_root.c b/test/zdtm/static/mntns_pivot_root.c
new file mode 100644
index 000000000..987b0da3b
--- /dev/null
+++ b/test/zdtm/static/mntns_pivot_root.c
@@ -0,0 +1,150 @@
+#include <sched.h>
+#include <signal.h>
+#include <fcntl.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <linux/limits.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#include "zdtmtst.h"
+#include "lock.h"
+
+const char *test_doc = "Check nested mntns with different root";
+const char *test_author = "Pavel Tikhomirov <ptikhomirov@virtuozzo.com>";
+
+char *dirname = "mntns_pivot_root.test";
+TEST_OPTION(dirname, string, "directory name", 1);
+
+char *source = "mntns_pivot_root";
+
+enum {
+	TEST_INIT = 0,
+	TEST_CHILD,
+	TEST_CHECK,
+	TEST_EXIT,
+	EMERGENCY_ABORT,
+};
+
+futex_t *futex;
+
+static int sys_pivot_root(const char *new_root, const char *put_old)
+{
+	return syscall(SYS_pivot_root, new_root, put_old);
+}
+
+#define BUF_SIZE 4096
+
+static int child(void)
+{
+	char *put_root = "put_root";
+	char *testfile = "testfile";
+	int fd;
+
+	if (unshare(CLONE_NEWNS)) {
+		pr_perror("unshare");
+		goto err;
+	}
+	/*
+	 * Setup new root
+	 */
+	mkdir(dirname, 0755);
+
+	if (mount(source, dirname, "tmpfs", 0, NULL)) {
+		pr_perror("mount tmpfs");
+		goto err;
+	}
+
+	if (mount(NULL, dirname, NULL, MS_PRIVATE, NULL)) {
+		pr_perror("make private");
+		goto err;
+	}
+
+	if (chdir(dirname)) {
+		pr_perror("chdir");
+		goto err;
+	}
+
+	mkdir(put_root, 0755);
+
+	if (sys_pivot_root(".", put_root)) {
+		pr_perror("pivot_root");
+		goto err;
+	}
+
+	if (umount2(put_root, MNT_DETACH)) {
+		pr_perror("umount2");
+		goto err;
+	}
+
+	fd = open(testfile, O_RDWR | O_CREAT | O_EXCL, 0666);
+	if (fd < 0) {
+		pr_perror("open");
+		goto err;
+	}
+	close(fd);
+
+	futex_set_and_wake(futex, TEST_CHILD);
+	futex_wait_while_lt(futex, TEST_CHECK);
+
+	if (access(testfile, F_OK)) {
+		pr_perror("access");
+		goto err;
+	}
+
+	futex_set_and_wake(futex, TEST_EXIT);
+	return 0;
+err:
+	futex_set_and_wake(futex, EMERGENCY_ABORT);
+	return 1;
+}
+
+int main(int argc, char **argv)
+{
+	int pid;
+
+	test_init(argc, argv);
+
+	/*
+	 * Setup futex for processes syncronization
+	 */
+	futex = mmap(NULL, sizeof(futex), PROT_WRITE | PROT_READ, MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+	if (futex == MAP_FAILED) {
+		pr_perror("mmap");
+		return 1;
+	}
+	futex_init(futex);
+
+	/*
+	 * Fork child which would have nested mntns
+	 */
+	pid = fork();
+	if (pid < 0) {
+		pr_perror("fork");
+		return 1;
+	} else if (pid == 0) {
+		exit(child());
+	}
+
+	futex_wait_while_lt(futex, TEST_CHILD);
+	if (futex_get(futex) == EMERGENCY_ABORT) {
+		pr_err("Fail in child\n");
+		return 1;
+	}
+
+	test_daemon();
+	test_waitsig();
+
+	futex_set_and_wake(futex, TEST_CHECK);
+	futex_wait_while_lt(futex, TEST_EXIT);
+	if (futex_get(futex) == EMERGENCY_ABORT) {
+		fail("Fail in child on check stage");
+		return 1;
+	}
+
+	waitpid(pid, NULL, 0);
+	pass();
+	return 0;
+}
diff --git a/test/zdtm/static/mntns_pivot_root.desc b/test/zdtm/static/mntns_pivot_root.desc
new file mode 100644
index 000000000..7657ba45c
--- /dev/null
+++ b/test/zdtm/static/mntns_pivot_root.desc
@@ -0,0 +1 @@
+{'flavor': 'ns uns', 'flags': 'suid'}