blackhole_dev_kunit.c

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * This tests the blackhole_dev that is created during the
 4 * net subsystem initialization. The test this module performs is
 5 * by injecting an skb into the stack with skb->dev as the
 6 * blackhole_dev and expects kernel to behave in a sane manner
 7 * (in other words, *not crash*)!
 8 *
 9 * Copyright (c) 2018, Mahesh Bandewar <maheshb@google.com>
10 */
11
12#include <kunit/test.h>
13#include <linux/module.h>
14#include <linux/skbuff.h>
15#include <linux/netdevice.h>
16#include <linux/udp.h>
17#include <linux/ipv6.h>
18
19#include <net/dst.h>
20
21#define SKB_SIZE  256
22#define HEAD_SIZE (14+40+8)	/* Ether + IPv6 + UDP */
23#define TAIL_SIZE 32		/* random tail-room */
24
25#define UDP_PORT 1234
26
27static void test_blackholedev(struct kunit *test)
28{
29	struct ipv6hdr *ip6h;
30	struct sk_buff *skb;
31	struct udphdr *uh;
32	int data_len;
33
34	skb = alloc_skb(SKB_SIZE, GFP_KERNEL);
35	KUNIT_ASSERT_NOT_NULL(test, skb);
36
37	/* Reserve head-room for the headers */
38	skb_reserve(skb, HEAD_SIZE);
39
40	/* Add data to the skb */
41	data_len = SKB_SIZE - (HEAD_SIZE + TAIL_SIZE);
42	memset(__skb_put(skb, data_len), 0xf, data_len);
43
44	/* Add protocol data */
45	/* (Transport) UDP */
46	uh = (struct udphdr *)skb_push(skb, sizeof(struct udphdr));
47	skb_set_transport_header(skb, 0);
48	uh->source = uh->dest = htons(UDP_PORT);
49	uh->len = htons(data_len);
50	uh->check = 0;
51	/* (Network) IPv6 */
52	ip6h = (struct ipv6hdr *)skb_push(skb, sizeof(struct ipv6hdr));
53	skb_set_network_header(skb, 0);
54	ip6h->hop_limit = 32;
55	ip6h->payload_len = htons(data_len + sizeof(struct udphdr));
56	ip6h->nexthdr = IPPROTO_UDP;
57	ip6h->saddr = in6addr_loopback;
58	ip6h->daddr = in6addr_loopback;
59	/* Ether */
60	skb_push(skb, sizeof(struct ethhdr));
61	skb_set_mac_header(skb, 0);
62
63	skb->protocol = htons(ETH_P_IPV6);
64	skb->pkt_type = PACKET_HOST;
65	skb->dev = blackhole_netdev;
66
67	/* Now attempt to send the packet */
68	KUNIT_EXPECT_EQ(test, dev_queue_xmit(skb), NET_XMIT_SUCCESS);
69}
70
71static struct kunit_case blackholedev_cases[] = {
72	KUNIT_CASE(test_blackholedev),
73	{},
74};
75
76static struct kunit_suite blackholedev_suite = {
77	.name = "blackholedev",
78	.test_cases = blackholedev_cases,
79};
80
81kunit_test_suite(blackholedev_suite);
82
83MODULE_AUTHOR("Mahesh Bandewar <maheshb@google.com>");
84MODULE_DESCRIPTION("module test of the blackhole_dev");
85MODULE_LICENSE("GPL");