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Code Issues Projects Releases Wiki Activity

1. Added document for sheep_net module.

Browse Source 
2. Fixed wrong use of ipip_hdr. It is for IP tunnel. This caused serious issues in IP packet filtering. Basically, it filtered out most packets sent from outsides. The correct way to get IP header destination IP address is ip_hdr.
3. Fixed ARP spoofing from guest OS to host OS. At anytime fake MAC address should be hided.
4. Changed module init and remove as non debug message.

Signed-off-by: Ricky Zhang <rickyzhang@gmail.com>
This commit is contained in:
Ricky Zhang 2016-08-18 02:00:00 -04:00
parent dc112290ac
commit 042574382e
2 changed files with 72 additions and 4 deletions
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47
BasiliskII/src/Unix/Linux/NetDriver/README.md Normal file
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@ -0,0 +1,47 @@
# What
​
sheep_net is a character virtual device that bridge between BasiliskII and Physical Ethernet card(P)
Here is logical diagram:
Guest Mac OS in emulation (G) <==> Basilisk II (B) <==> /dev/sheep_net (S) <==> Physical Ethernet card on host (P)
sheep_net module masquerade and de-masquerade MAC address on Ethernet frame so that Guest OS and host share the same MAC address with different IP.
See details in [IP aliasing](https://en.wikipedia.org/wiki/IP_aliasing)
# How
## How it works
Sample Setting:
Guest Mac OS IP: 192.168.2.2, Fake MAC address: 84:38:35:5e:c5:5b
Host OS Physical Ethernet car IP: 192.168.2.3, physical MAC address: 84:38:35:5e:c5:5a
From outside, we see 192.168.2.2 and 192.168.2.3 share the same physical MAC address: 84:38:35:5e:c5:5a
From insides, sheep_net module masquerade and de-masquerade MAC address of Ethernet packet between Basilisk and
```
B ==> S ==> P: de-masquerade MAC, convert Fake to Physical
B <== S <== P: masquerade MAC, convert Physical to Fake
```
## How to compile
```
​cd Linux/NetDriver
make
//create sheep_net device node
sudo make dev
sudo chown [user account] /dev/sheep_net
sudo make install
sudo modprobe sheep_net
```
## How to use
1. Disable IP forwarding on host (Recommended: By disabling it, guest OS won't receive duplicate IP packet from host again.)
2. Disable firewall on host (Recommended: host may send ICMP host unreachable to gateway. Or you can disable ICMP sending from host by changing iptables.)
3. sudo modprobe sheep_net
4. sudo chown [user account] /dev/sheep_net
5. Launch BasiliskII, choose your physical Ethernet card interface in network tab

29
BasiliskII/src/Unix/Linux/NetDriver/sheep_net.c
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@ -223,7 +223,7 @@ int init_module(void)
/* Register driver */ /* Register driver */
ret = misc_register(&sheep_net_device); ret = misc_register(&sheep_net_device);
D(bug("Sheep net driver installed\n")); printk("sheep net: driver installed\n");
return ret; return ret;
} }
@ -236,7 +236,7 @@ void cleanup_module(void)
{ {
/* Unregister driver */ /* Unregister driver */
misc_deregister(&sheep_net_device); misc_deregister(&sheep_net_device);
D(bug("Sheep net driver removed\n")); printk("sheep net: driver removed\n");
} }
@ -500,7 +500,8 @@ static ssize_t sheep_net_write(struct file *f, const char *buf, size_t count, lo
netif_rx(skb); netif_rx(skb);
return count; return count;
} }
if (skb->data[0] & ETH_ADDR_MULTICAST) { /* Relay multicast for host process except ARP packet */
if ((skb->data[0] & ETH_ADDR_MULTICAST) && (eth_hdr(skb)->h_proto != htons(ETH_P_ARP))) {
/* We can't clone the skb since we will manipulate the data below */ /* We can't clone the skb since we will manipulate the data below */
struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC); struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC);
if (lskb) { if (lskb) {
@ -606,6 +607,9 @@ static int sheep_net_ioctl(struct inode *inode, struct file *f, unsigned int cod
} }
skt_set_dead(v->skt); skt_set_dead(v->skt);
/*initialize ipfilter*/
v->ipfilter = 0;
/* Attach packet handler */ /* Attach packet handler */
v->pt.type = htons(ETH_P_ALL); v->pt.type = htons(ETH_P_ALL);
v->pt.dev = v->ether; v->pt.dev = v->ether;
@ -746,8 +750,25 @@ static int sheep_net_receiver(struct sk_buff *skb, struct net_device *dev, struc
/* Apply any filters here (if fake is true, then we *know* we want this packet) */ /* Apply any filters here (if fake is true, then we *know* we want this packet) */
if (!fake) { if (!fake) {
if ((skb->protocol == htons(ETH_P_IP)) if ((skb->protocol == htons(ETH_P_IP))
&& (!v->ipfilter || (ntohl(ipip_hdr(skb)->daddr) != v->ipfilter && !multicast))) && (!v->ipfilter || (ntohl(ip_hdr(skb)->daddr) != v->ipfilter && !multicast))) {
#if DEBUG
char source[16];
snprintf(source, 16, "%pI4", &ip_hdr(skb)->saddr);
D(bug("sheep_net: drop incoming IP packet %s for filter %d.%d.%d.%d\n",
source,
(v->ipfilter >> 24) & 0xff, (v->ipfilter >> 16) & 0xff, (v->ipfilter >> 8) & 0xff, v->ipfilter & 0xff));
#endif
goto drop; goto drop;
}
#if DEBUG
else{
if(!multicast){
char source[16];
snprintf(source, 16, "%pI4", &ip_hdr(skb)->saddr);
D(bug("sheep_net: retain incoming unicast IP packet %s\n", source));
}
}
#endif
} }
/* Masquerade (we are typically a clone - best to make a real copy) */ /* Masquerade (we are typically a clone - best to make a real copy) */