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Message-Id: <20190627194309.94291-1-maheshb@google.com>
Date: Thu, 27 Jun 2019 12:43:09 -0700
From: Mahesh Bandewar <maheshb@...gle.com>
To: Netdev <netdev@...r.kernel.org>
Cc: Eric Dumazet <edumazet@...gle.com>,
David Miller <davem@...emloft.net>,
Michael Chan <michael.chan@...adcom.com>,
Daniel Axtens <dja@...ens.net>,
Mahesh Bandewar <mahesh@...dewar.net>,
Mahesh Bandewar <maheshb@...gle.com>
Subject: [PATCHv2 next 3/3] 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@...gle.com>
---
v1 -> v2
fixed the conflict resolution in selftests Makefile
lib/Kconfig.debug | 9 ++
lib/Makefile | 1 +
lib/test_blackhole_dev.c | 100 ++++++++++++++++++
tools/testing/selftests/net/Makefile | 2 +-
tools/testing/selftests/net/config | 1 +
.../selftests/net/test_blackhole_dev.sh | 11 ++
6 files changed, 123 insertions(+), 1 deletion(-)
create mode 100644 lib/test_blackhole_dev.c
create mode 100755 tools/testing/selftests/net/test_blackhole_dev.sh
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index cbdfae379896..79d96e1614f5 100644
--- 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 BPF filter 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 fb7697031a79..c293624d3664 100644
--- 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
index 000000000000..4c40580a99a3
--- /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@...gle.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@...gle.com>");
+MODULE_LICENSE("GPL");
diff --git a/tools/testing/selftests/net/Makefile b/tools/testing/selftests/net/Makefile
index 9a275d932fd5..1b24e36b4047 100644
--- 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 89f84b5118bf..e4b878d95ba0 100644
--- 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
index 000000000000..3119b80e711f
--- /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
--
2.22.0.410.gd8fdbe21b5-goog
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