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: Mahesh Bandewar <maheshb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index cbdfae37989653410332bc9acd9dd1237ace1712..99272b5dd98087ef0ae9a283833d20684e789763 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -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

diff --git a/lib/Makefile b/lib/Makefile
index dcb558c7554d9fb6cfaa1ce92c786a1a93ca465e..6ac44fe2a37f60024190c5d0b1620b871d656c1d 100644 (file)
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -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/
 

diff --git a/lib/test_blackhole_dev.c b/lib/test_blackhole_dev.c
new file mode 100644 (file)
index 0000000..4c40580
--- /dev/null
+++ b/lib/test_blackhole_dev.c
@@ -0,0 +1,100 @@
+// 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");

diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 9a275d932fd5ae9bbc01e984a2c677fcc3a82d31..1b24e36b404781207c43cac6e4c759e65354c006 100644 (file)
--- a/tools/testing/selftests/net/Makefile
+++ b/tools/testing/selftests/net/Makefile
@@ -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

diff --git a/tools/testing/selftests/net/config b/tools/testing/selftests/net/config
index 89f84b5118bfa657487649e37e0db29f14c4bc3b..e4b878d95ba01f96a1bbf9cc7a2b15f597fba5db 100644 (file)
--- a/tools/testing/selftests/net/config
+++ b/tools/testing/selftests/net/config
@@ -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

diff --git a/tools/testing/selftests/net/test_blackhole_dev.sh b/tools/testing/selftests/net/test_blackhole_dev.sh
new file mode 100755 (executable)
index 0000000..3119b80
--- /dev/null
+++ b/tools/testing/selftests/net/test_blackhole_dev.sh
@@ -0,0 +1,11 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# Runs blackhole-dev test using blackhole-dev kernel module
+
+if /sbin/modprobe -q test_blackhole_dev ; then
+       /sbin/modprobe -q -r test_blackhole_dev;
+       echo "test_blackhole_dev: ok";
+else
+       echo "test_blackhole_dev: [FAIL]";
+       exit 1;
+fi