zdtm: Check that out-of-root file survives

If a task opens a file, then goes chroot, CRIU should still
be able to dump and restore the now-invisible file.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -95,6 +95,7 @@ static/proc-self
 static/grow_map
 static/grow_map02
 static/chroot
+static/chroot-file
 "
 # Duplicate list with ns/ prefix
 TEST_LIST=$TEST_LIST$(echo $TEST_LIST | tr ' ' '\n' | sed 's#^#ns/#')
@@ -142,6 +143,7 @@ fanotify00
 sk-netlink
 tun
 chroot
+chroot-file
 "
 
 source $(readlink -f `dirname $0`/env.sh) || exit 1

test/zdtm/live/static/Makefile

@@ -143,7 +143,8 @@ TST_DIR		=				\
 		overmount_sock			\
 
 TST_DIR_FILE	=				\
-		chroot
+		chroot				\
+		chroot-file
 
 TST		=				\
 		$(TST_NOFILE)			\

test/zdtm/live/static/chroot-file.c

+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/wait.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc	= "Check that out-of-root file survives";
+const char *test_author	= "Pavel Emelianov <xemul@parallels.com>";
+
+char *dirname;
+TEST_OPTION(dirname, string, "directory name", 1);
+char *filename;
+TEST_OPTION(filename, string, "file name", 1);
+
+#define MSG	"out-file-contents"
+
+static int make_file(char *name)
+{
+	int fd;
+
+	fd = open(name, O_RDWR | O_CREAT, 0666);
+	if (fd < 0)
+		return -1;
+
+	if (write(fd, MSG, sizeof(MSG)) != sizeof(MSG))
+		return -1;
+
+	return fd;
+}
+
+static int check_file(int fd)
+{
+	char r[sizeof(MSG)];
+
+	lseek(fd, 0, SEEK_SET);
+	if (read(fd, r, sizeof(r)) != sizeof(MSG))
+		return -1;
+
+	if (memcmp(r, MSG, sizeof(MSG)))
+		return -1;
+
+	return 0;
+}
+
+#define SUCCESS		0
+#define ERR_PIPES	(char)0x7f
+/* bitmap of errors */
+#define ERR_IN_FILE	1
+#define ERR_ROOT	2
+#define ERR_DIR		4
+#define ERR_CHDIR	8
+#define ERR_ROOT2	4
+
+int main(int argc, char **argv)
+{
+	int pid, pipe_prep[2], pipe_goon[2], pipe_res[2];
+	char res;
+	int fd, fd2;
+
+	test_init(argc, argv);
+
+	pipe(pipe_prep);
+	pipe(pipe_goon);
+	pipe(pipe_res);
+	pid = test_fork();
+	if (pid != 0) {
+		close(pipe_prep[1]);
+		close(pipe_goon[0]);
+		close(pipe_res[1]);
+
+		res = ERR_PIPES;
+		read(pipe_prep[0], &res, 1);
+		if (res != SUCCESS) {
+			if (res == ERR_PIPES)
+				err("broken pipes");
+			else {
+				if (res & ERR_IN_FILE)
+					err("inside-root file fail");
+				if (res & ERR_ROOT)
+					err("chroot fail");
+				if (res & ERR_DIR)
+					err("mkdir fail");
+				if (res & ERR_CHDIR)
+					err("chrid fail");
+			}
+			return 0;
+		}
+
+		test_daemon();
+		test_waitsig();
+		close(pipe_goon[1]);
+
+		res = ERR_PIPES;
+		read(pipe_res[0], &res, 1);
+
+		if (res == SUCCESS)
+			pass();
+		else if (res == ERR_PIPES)
+			fail("broken pipes");
+		else {
+			if (res & ERR_IN_FILE)
+				fail("opened file broken");
+			if (res & ERR_ROOT)
+				fail("open in chroot succeeded");
+			if (res & ERR_ROOT2)
+				fail("open in chroot might work");
+		}
+
+		wait(NULL);
+		return 0;
+	}
+
+	close(pipe_prep[0]);
+	close(pipe_goon[1]);
+	close(pipe_res[0]);
+
+	fd = make_file(filename);
+	if (fd < 0) {
+		res = ERR_IN_FILE;
+		goto err;
+	}
+
+	if (mkdir(dirname, 0700)) {
+		res = ERR_DIR;
+		goto err;
+	}
+
+	if (chroot(dirname)) {
+		res = ERR_ROOT;
+		goto err;
+	}
+
+	if (chdir("/")) {
+		res = ERR_CHDIR;
+		goto err;
+	}
+
+	res = SUCCESS;
+	write(pipe_prep[1], &res, 1);
+	close(pipe_prep[1]);
+	read(pipe_goon[0], &res, 1);
+
+	res = SUCCESS;
+
+	if (check_file(fd))
+		res |= ERR_IN_FILE;
+
+	fd2 = open(filename, O_RDWR);
+	if (fd2 >= 0) {
+		res |= ERR_ROOT;
+		close(fd2);
+	} else if (errno != ENOENT)
+		res |= ERR_ROOT2;
+
+	write(pipe_res[1], &res, 1);
+	exit(0);
+
+err:
+	write(pipe_prep[1], &res, 1);
+	exit(0);
+}