zdtm: add new dumpable01 test to check that dumpable flag is preserved

This confirms that the fix in commit d5bb7e97 to preserve the dumpable flag
after migration is working as expected.

In this test case, the dumpable flag is expected to always be set to 1, as
test_init will use prctl to reset it to 1 after using setuid and setgid.

Tested:
- # test/zdtm.sh static/dumpable01
  Test: zdtm/live/static/dumpable01, Result: PASS
- # test/zdtm.sh ns/static/dumpable01
  Test: zdtm/live/static/dumpable01, Result: PASS
- Confirmed that the test fails after reverting commit d5bb7e97.
Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -107,6 +107,7 @@ static/chroot
 static/chroot-file
 static/rtc
 transition/maps007
+static/dumpable01
 "
 # Duplicate list with ns/ prefix
 TEST_LIST=$TEST_LIST$(echo $TEST_LIST | tr ' ' '\n' | sed 's#^#ns/#')

test/zdtm/.gitignore

@@ -15,6 +15,7 @@
 /live/static/cwd01
 /live/static/deleted_dev
 /live/static/deleted_unix_sock
+/live/static/dumpable01
 /live/static/env00
 /live/static/eventfs00
 /live/static/fanotify00

test/zdtm/live/static/Makefile

@@ -109,6 +109,7 @@ TST_NOFILE	=				\
 		stopped				\
 		rtc				\
 		clean_mntns			\
+		dumpable01			\
 #		jobctl00			\
 
 TST_FILE	=				\

test/zdtm/live/static/dumpable01.c

+#include <sys/prctl.h>
+#include <sys/types.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "zdtmtst.h"
+
+const char *test_doc    = "Check dumpable flag handling (dumpable case)";
+const char *test_author = "Filipe Brandenburger <filbranden@google.com>";
+
+int main(int argc, char **argv)
+{
+	int save_dumpable;
+	int dumpable;
+
+	test_init(argc, argv);
+
+	save_dumpable = prctl(PR_GET_DUMPABLE);
+	if (save_dumpable < 0) {
+		err("error getting prctl(PR_GET_DUMPABLE) before dump");
+		return 1;
+	}
+#ifdef DEBUG
+	test_msg("DEBUG: before dump: dumpable=%d\n", save_dumpable);
+#endif
+
+	/* Wait for criu dump and restore. */
+	test_daemon();
+	test_waitsig();
+
+	dumpable = prctl(PR_GET_DUMPABLE);
+	if (dumpable < 0) {
+		err("error getting prctl(PR_GET_DUMPABLE) after restore");
+		return 1;
+	}
+#ifdef DEBUG
+	test_msg("DEBUG: after dump: dumpable=%d\n", dumpable);
+#endif
+
+	if (dumpable != save_dumpable) {
+		errno = 0;
+		fail("dumpable flag was not preserved over migration");
+		return 1;
+	}
+
+	pass();
+	return 0;
+}