selftests/bpf: Test attaching a bpf qdisc with incomplete operators

Implement .destroy in bpf_fq and bpf_fifo as it is now mandatory.

Test attaching a bpf qdisc with a missing operator .init. This is not
allowed as bpf qdisc qdisc_watchdog_cancel() could have been called with
an uninitialized timer.

Signed-off-by: Amery Hung <ameryhung@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

tools/testing/selftests/bpf/prog_tests/bpf_qdisc.c

@@ -7,6 +7,7 @@
 #include "network_helpers.h"
 #include "bpf_qdisc_fifo.skel.h"
 #include "bpf_qdisc_fq.skel.h"
+#include "bpf_qdisc_fail__incompl_ops.skel.h"
 
 #define LO_IFINDEX 1
 
@@ -159,6 +160,22 @@ static void test_qdisc_attach_to_non_root(void)
 	bpf_qdisc_fifo__destroy(fifo_skel);
 }
 
+static void test_incompl_ops(void)
+{
+	struct bpf_qdisc_fail__incompl_ops *skel;
+	struct bpf_link *link;
+
+	skel = bpf_qdisc_fail__incompl_ops__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "bpf_qdisc_fifo__open_and_load"))
+		return;
+
+	link = bpf_map__attach_struct_ops(skel->maps.test);
+	if (!ASSERT_ERR_PTR(link, "bpf_map__attach_struct_ops"))
+		bpf_link__destroy(link);
+
+	bpf_qdisc_fail__incompl_ops__destroy(skel);
+}
+
 static int get_default_qdisc(char *qdisc_name)
 {
 	FILE *f;
@@ -230,6 +247,8 @@ void test_bpf_qdisc(void)
 		test_qdisc_attach_to_mq();
 	if (test__start_subtest("attach to non root"))
 		test_qdisc_attach_to_non_root();
+	if (test__start_subtest("incompl_ops"))
+		test_incompl_ops();
 
 	netns_free(netns);
 }

tools/testing/selftests/bpf/progs/bpf_qdisc_fail__incompl_ops.c

@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <vmlinux.h>
+#include "bpf_experimental.h"
+#include "bpf_qdisc_common.h"
+
+char _license[] SEC("license") = "GPL";
+
+SEC("struct_ops")
+int BPF_PROG(bpf_qdisc_test_enqueue, struct sk_buff *skb, struct Qdisc *sch,
+	     struct bpf_sk_buff_ptr *to_free)
+{
+	bpf_qdisc_skb_drop(skb, to_free);
+	return NET_XMIT_DROP;
+}
+
+SEC("struct_ops")
+struct sk_buff *BPF_PROG(bpf_qdisc_test_dequeue, struct Qdisc *sch)
+{
+	return NULL;
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_reset, struct Qdisc *sch)
+{
+}
+
+SEC("struct_ops")
+void BPF_PROG(bpf_qdisc_test_destroy, struct Qdisc *sch)
+{
+}
+
+SEC(".struct_ops")
+struct Qdisc_ops test = {
+	.enqueue   = (void *)bpf_qdisc_test_enqueue,
+	.dequeue   = (void *)bpf_qdisc_test_dequeue,
+	.reset     = (void *)bpf_qdisc_test_reset,
+	.destroy   = (void *)bpf_qdisc_test_destroy,
+	.id        = "bpf_qdisc_test",
+};
+

tools/testing/selftests/bpf/progs/bpf_qdisc_fifo.c

@@ -109,12 +109,18 @@ void BPF_PROG(bpf_fifo_reset, struct Qdisc *sch)
 	sch->q.qlen = 0;
 }
 
+SEC("struct_ops")
+void BPF_PROG(bpf_fifo_destroy, struct Qdisc *sch)
+{
+}
+
 SEC(".struct_ops")
 struct Qdisc_ops fifo = {
 	.enqueue   = (void *)bpf_fifo_enqueue,
 	.dequeue   = (void *)bpf_fifo_dequeue,
 	.init      = (void *)bpf_fifo_init,
 	.reset     = (void *)bpf_fifo_reset,
+	.destroy   = (void *)bpf_fifo_destroy,
 	.id        = "bpf_fifo",
 };
 

tools/testing/selftests/bpf/progs/bpf_qdisc_fq.c

@@ -740,11 +740,17 @@ int BPF_PROG(bpf_fq_init, struct Qdisc *sch, struct nlattr *opt,
 	return 0;
 }
 
+SEC("struct_ops")
+void BPF_PROG(bpf_fq_destroy, struct Qdisc *sch)
+{
+}
+
 SEC(".struct_ops")
 struct Qdisc_ops fq = {
 	.enqueue   = (void *)bpf_fq_enqueue,
 	.dequeue   = (void *)bpf_fq_dequeue,
 	.reset     = (void *)bpf_fq_reset,
 	.init      = (void *)bpf_fq_init,
+	.destroy   = (void *)bpf_fq_destroy,
 	.id        = "bpf_fq",
 };