zdtm: test for mlocked area restores if programm have no credentials

Test maps 17 pages and mlocks them, then changes user id from root
to 18943, after c/r checks that MAP_LOCKED bit is set for that vma.
Signed-off-by: Pavel Tikhomirov <ptikhomirov@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

test/zdtm.sh

@@ -25,6 +25,7 @@ static/maps01
 static/maps02
 static/maps04
 static/maps05
+static/mlock_setuid
 static/maps_file_prot
 static/mprotect00
 static/mtime_mmap
@@ -203,6 +204,7 @@ TEST_SUID_LIST="
 pid00
 caps00
 maps01
+mlock_setuid
 groups
 sched_prio00
 sched_policy00

test/zdtm/live/static/Makefile

@@ -70,6 +70,7 @@ TST_NOFILE	=				\
 		maps03				\
 		maps04				\
 		maps05				\
+		mlock_setuid			\
 		xids00				\
 		groups				\
 		pdeath_sig			\
@@ -290,6 +291,7 @@ sigpending:		override LDLIBS += -lrt
 vdso01:			override LDLIBS += -lrt
 mntns_link_remap:	override CFLAGS += -DZDTM_LINK_REMAP
 maps02:		get_smaps_bits.o
+mlock_setuid:		get_smaps_bits.o
 
 $(LIB):	force
 	$(Q) $(MAKE) -C $(LIBDIR)

test/zdtm/live/static/mlock_setuid.c

+#include <sys/types.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include "zdtmtst.h"
+
+#define MEM_SIZE (69632)
+
+int main(int argc, char **argv)
+{
+	int ret;
+	void *start;
+	unsigned long new_flags = 0;
+	unsigned long new_madv = 0;
+	test_init(argc, argv);
+
+	test_msg("Alloc vma of size %d\n", MEM_SIZE);
+	start = mmap(NULL, MEM_SIZE, PROT_READ | PROT_WRITE,
+	             MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (start == MAP_FAILED) {
+		err("mmap failed");
+		return -1;
+	}
+
+	test_msg("Lock vma from %lx to %lx\n", start, start + MEM_SIZE);
+	ret = mlock(start, MEM_SIZE);
+	if (ret < 0) {
+		err("mlock");
+		return -1;
+	}
+
+	test_daemon();
+
+	test_msg("Setuid to 18943\n");
+	ret = setuid(18943);
+	if (ret < 0) {
+		err("setuid");
+		return -1;
+	}
+
+	test_waitsig();
+
+	ret = get_smaps_bits((unsigned long)start, &new_flags, &new_madv);
+	if (ret < 0)
+		return -1;
+
+	test_msg("Check smaps flags for MAP_LOCKED\n");
+	if (new_flags & MAP_LOCKED) {
+		pass();
+	} else {
+		fail("Vma is not locked after c/r\n");
+		return -1;
+	}
+
+	return 0;
+}