pf tests: Test name handling

Provoke a situation where two interfaces have the same name, and verify
pf's reaction to this.

tests/sys/netpfil/pf/Makefile

@@ -9,6 +9,7 @@ ATF_TESTS_SH+=	anchor \
 		pass_block \
 		forward \
 		fragmentation \
+		names \
 		set_tos \
 		route_to \
 		synproxy \

tests/sys/netpfil/pf/names.sh

@@ -0,0 +1,34 @@
+# $FreeBSD$
+
+. $(atf_get_srcdir)/utils.subr
+
+atf_test_case "names" "cleanup"
+names_head()
+{
+	atf_set descr 'Test overlapping names'
+	atf_set require.user root
+}
+
+names_body()
+{
+	pft_init
+
+	epair=$(pft_mkepair)
+
+	pft_mkjail alcatraz ${epair}b
+	ifconfig ${epair}a name foo
+	jexec alcatraz ifconfig ${epair}b name foo
+
+	jail -r alcatraz
+	ifconfig foo destroy
+}
+
+names_cleanup()
+{
+	pft_cleanup
+}
+
+atf_init_test_cases()
+{
+	atf_add_test_case "names"
+}