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authorMahesh Bandewar <maheshb@google.com>2019-07-02 00:39:01 +0300
committerDavid S. Miller <davem@davemloft.net>2019-07-02 05:34:46 +0300
commit509e56b37cc32c9b5fc2be585c25d1e60d6a1d73 (patch)
tree30d85bf915bacf13f14ea2d3c40bbc68815d799d /lib/test_blackhole_dev.c
parent8d7017fd621d02ff0d47d19484350c2356828483 (diff)
downloadlinux-509e56b37cc32c9b5fc2be585c25d1e60d6a1d73.tar.xz
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>
Diffstat (limited to 'lib/test_blackhole_dev.c')
-rw-r--r--lib/test_blackhole_dev.c100
1 files changed, 100 insertions, 0 deletions
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@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");