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- // 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 <[email protected]>
- */
- #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 <[email protected]>");
- MODULE_LICENSE("GPL");
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