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Commit 509e56b3 authored by Mahesh Bandewar's avatar Mahesh Bandewar Committed by David S. Miller
Browse files

blackhole_dev: add a selftest 



Since this is not really a device with all capabilities, this test
ensures that it has *enough* to make it through the data path
without causing unwanted side-effects (read crash!).

Signed-off-by: default avatarMahesh Bandewar <maheshb@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8d7017fd

lib/Kconfig.debug

+9 −0
Original line number Diff line number Diff line
@@ -1909,6 +1909,15 @@ config TEST_BPF 


	  If unsure, say N.



config TEST_BLACKHOLE_DEV

	tristate "Test blackhole netdev functionality"

	depends on m && NET

	help

	  This builds the "test_blackhole_dev" module that validates the

	  data path through this blackhole netdev.



	  If unsure, say N.



config FIND_BIT_BENCHMARK

	tristate "Test find_bit functions"

	help

lib/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -91,6 +91,7 @@ obj-$(CONFIG_TEST_DEBUG_VIRTUAL) += test_debug_virtual.o 
obj-$(CONFIG_TEST_MEMCAT_P) += test_memcat_p.o

obj-$(CONFIG_TEST_OBJAGG) += test_objagg.o

obj-$(CONFIG_TEST_STACKINIT) += test_stackinit.o

obj-$(CONFIG_TEST_BLACKHOLE_DEV) += test_blackhole_dev.o



obj-$(CONFIG_TEST_LIVEPATCH) += livepatch/

lib/test_blackhole_dev.c

0 → 100644
+100 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * This module tests the blackhole_dev that is created during the

 * net subsystem initialization. The test this module performs is

 * by injecting an skb into the stack with skb->dev as the

 * blackhole_dev and expects kernel to behave in a sane manner

 * (in other words, *not crash*)!

 *

 * Copyright (c) 2018, Mahesh Bandewar <maheshb@google.com>

 */



#include <linux/init.h>

#include <linux/module.h>

#include <linux/printk.h>

#include <linux/skbuff.h>

#include <linux/netdevice.h>

#include <linux/udp.h>

#include <linux/ipv6.h>



#include <net/dst.h>



#define SKB_SIZE  256

#define HEAD_SIZE (14+40+8)	/* Ether + IPv6 + UDP */

#define TAIL_SIZE 32		/* random tail-room */



#define UDP_PORT 1234



static int __init test_blackholedev_init(void)

{

	struct ipv6hdr *ip6h;

	struct sk_buff *skb;

	struct ethhdr *ethh;

	struct udphdr *uh;

	int data_len;

	int ret;



	skb = alloc_skb(SKB_SIZE, GFP_KERNEL);

	if (!skb)

		return -ENOMEM;



	/* Reserve head-room for the headers */

	skb_reserve(skb, HEAD_SIZE);



	/* Add data to the skb */

	data_len = SKB_SIZE - (HEAD_SIZE + TAIL_SIZE);

	memset(__skb_put(skb, data_len), 0xf, data_len);



	/* Add protocol data */

	/* (Transport) UDP */

	uh = (struct udphdr *)skb_push(skb, sizeof(struct udphdr));

	skb_set_transport_header(skb, 0);

	uh->source = uh->dest = htons(UDP_PORT);

	uh->len = htons(data_len);

	uh->check = 0;

	/* (Network) IPv6 */

	ip6h = (struct ipv6hdr *)skb_push(skb, sizeof(struct ipv6hdr));

	skb_set_network_header(skb, 0);

	ip6h->hop_limit = 32;

	ip6h->payload_len = data_len + sizeof(struct udphdr);

	ip6h->nexthdr = IPPROTO_UDP;

	ip6h->saddr = in6addr_loopback;

	ip6h->daddr = in6addr_loopback;

	/* Ether */

	ethh = (struct ethhdr *)skb_push(skb, sizeof(struct ethhdr));

	skb_set_mac_header(skb, 0);



	skb->protocol = htons(ETH_P_IPV6);

	skb->pkt_type = PACKET_HOST;

	skb->dev = blackhole_netdev;



	/* Now attempt to send the packet */

	ret = dev_queue_xmit(skb);



	switch (ret) {

	case NET_XMIT_SUCCESS:

		pr_warn("dev_queue_xmit() returned NET_XMIT_SUCCESS\n");

		break;

	case NET_XMIT_DROP:

		pr_warn("dev_queue_xmit() returned NET_XMIT_DROP\n");

		break;

	case NET_XMIT_CN:

		pr_warn("dev_queue_xmit() returned NET_XMIT_CN\n");

		break;

	default:

		pr_err("dev_queue_xmit() returned UNKNOWN(%d)\n", ret);

	}



	return 0;

}



static void __exit test_blackholedev_exit(void)

{

	pr_warn("test_blackholedev module terminating.\n");

}



module_init(test_blackholedev_init);

module_exit(test_blackholedev_exit);



MODULE_AUTHOR("Mahesh Bandewar <maheshb@google.com>");

MODULE_LICENSE("GPL");

tools/testing/selftests/net/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ CFLAGS = -Wall -Wl,--no-as-needed -O2 -g 
CFLAGS += -I../../../../usr/include/



TEST_PROGS := run_netsocktests run_afpackettests test_bpf.sh netdevice.sh \

	      rtnetlink.sh xfrm_policy.sh

	      rtnetlink.sh xfrm_policy.sh test_blackhole_dev.sh

TEST_PROGS += fib_tests.sh fib-onlink-tests.sh pmtu.sh udpgso.sh ip_defrag.sh

TEST_PROGS += udpgso_bench.sh fib_rule_tests.sh msg_zerocopy.sh psock_snd.sh

TEST_PROGS += udpgro_bench.sh udpgro.sh test_vxlan_under_vrf.sh reuseport_addr_any.sh

tools/testing/selftests/net/config

+1 −0
Original line number Diff line number Diff line
@@ -27,3 +27,4 @@ CONFIG_NFT_CHAIN_NAT_IPV6=m 
CONFIG_NFT_CHAIN_NAT_IPV4=m

CONFIG_NET_SCH_FQ=m

CONFIG_NET_SCH_ETF=m

CONFIG_TEST_BLACKHOLE_DEV=m