Linux/NetDriver/sheep_net.c

/*
 *  sheep_net.c - Linux driver for SheepShaver/Basilisk II networking (access to raw Ethernet packets)
 *
 *  sheep_net (C) 1999-2001 Mar"c" Hellwig and Christian Bauer
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/version.h>
#include <linux/miscdevice.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/if_arp.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/in.h>
#include <linux/wait.h>
#include <net/sock.h>
#include <net/arp.h>
#include <net/ip.h>
#include <asm/uaccess.h>

/* Compatibility glue */
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
#define LINUX_24
#else
#define net_device device
typedef struct wait_queue *wait_queue_head_t;
#define init_waitqueue_head(x) *(x)=NULL
#endif

#define DEBUG 0

#define bug printk
#if DEBUG
#define D(x) (x);
#else
#define D(x) ;
#endif


/* Constants */
#define SHEEP_NET_MINOR 198             /* Driver minor number */
#define MAX_QUEUE 32                    /* Maximum number of packets in queue */
#define PROT_MAGIC 1520                 /* Our "magic" protocol type */

#define ETH_ADDR_MULTICAST 0x1

#define SIOC_MOL_GET_IPFILTER SIOCDEVPRIVATE
#define SIOC_MOL_SET_IPFILTER (SIOCDEVPRIVATE + 1)

/* Prototypes */
static int sheep_net_open(struct inode *inode, struct file *f);
static int sheep_net_release(struct inode *inode, struct file *f);
static ssize_t sheep_net_read(struct file *f, char *buf, size_t count, loff_t *off);
static ssize_t sheep_net_write(struct file *f, const char *buf, size_t count, loff_t *off);
static unsigned int sheep_net_poll(struct file *f, struct poll_table_struct *wait);
static int sheep_net_ioctl(struct inode *inode, struct file *f, unsigned int code, unsigned long arg);
static int sheep_net_receiver(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt);


/*
 *  Driver private variables
 */

struct SheepVars {
        struct net_device *ether;       /* The Ethernet device we're attached to */
        struct sock *skt;                       /* Socket for communication with Ethernet card */
        struct sk_buff_head queue;      /* Receiver packet queue */
        struct packet_type pt;          /* Receiver packet type */
        wait_queue_head_t wait;         /* Wait queue for blocking read operations */
        u32 ipfilter;                           /* Only receive IP packets destined for this address (host byte order) */
        char eth_addr[6];                       /* Hardware address of the Ethernet card */
        char fake_addr[6];                      /* Local faked hardware address (what SheepShaver sees) */
};


/*
 *  file_operations structure - has function pointers to the
 *  various entry points for device operations
 */

static struct file_operations sheep_net_fops = {
        read:           sheep_net_read,
        write:          sheep_net_write,
        poll:           sheep_net_poll,
        ioctl:          sheep_net_ioctl,
        open:           sheep_net_open,
        release:        sheep_net_release,
};


/*
 *  miscdevice structure for driver initialization
 */

static struct miscdevice sheep_net_device = {
        SHEEP_NET_MINOR,        /* minor number */
        "sheep_net",            /* name */
        &sheep_net_fops,
        NULL,
        NULL
};


/*
 *  Initialize module
 */

int init_module(void)
{
        int ret;

        /* Register driver */
        ret = misc_register(&sheep_net_device);
        D(bug("Sheep net driver installed\n"));
        return ret;
}


/*
 *  Deinitialize module
 */

int cleanup_module(void)
{
        int ret;

        /* Unregister driver */
        ret = misc_deregister(&sheep_net_device);
        D(bug("Sheep net driver removed\n"));
        return ret;
}


/*
 *  Driver open() function
 */

static int sheep_net_open(struct inode *inode, struct file *f)
{
        struct SheepVars *v;
        D(bug("sheep_net: open\n"));

        /* Must be opened with read permissions */
        if ((f->f_flags & O_ACCMODE) == O_WRONLY)
                return -EPERM;

        /* Allocate private variables */
        v = (struct SheepVars *)f->private_data = kmalloc(sizeof(struct SheepVars), GFP_USER);
        if (v == NULL)
                return -ENOMEM;
        memset(v, 0, sizeof(struct SheepVars));
        skb_queue_head_init(&v->queue);
        init_waitqueue_head(&v->wait);
        v->fake_addr[0] = 0xfe;
        v->fake_addr[1] = 0xfd;
        v->fake_addr[2] = 0xde;
        v->fake_addr[3] = 0xad;
        v->fake_addr[4] = 0xbe;
        v->fake_addr[5] = 0xef;

        /* Yes, we're open */
        MOD_INC_USE_COUNT;
        return 0;
}


/*
 *  Driver release() function
 */

static int sheep_net_release(struct inode *inode, struct file *f)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        struct sk_buff *skb;
        D(bug("sheep_net: close\n"));

        /* Detach from Ethernet card */
        if (v->ether) {
                dev_remove_pack(&v->pt);
                sk_free(v->skt);
                v->skt = NULL;
#ifdef LINUX_24
                dev_put( v->ether );
#endif
                v->ether = NULL;
        }

        /* Empty packet queue */
        while ((skb = skb_dequeue(&v->queue)) != NULL)
                dev_kfree_skb(skb);

        /* Free private variables */
        kfree(v);

        /* Sorry, we're closed */
        MOD_DEC_USE_COUNT;
        return 0;
}


/*
 *  Check whether an Ethernet address is the local (attached) one or
 *  the fake one
 */

static inline int is_local_addr(struct SheepVars *v, void *a)
{
        return memcmp(a, v->eth_addr, 6) == 0;
}

static inline int is_fake_addr(struct SheepVars *v, void *a)
{
        return memcmp(a, v->fake_addr, 6) == 0;
}


/* 
 * Outgoing packet. Replace the fake enet addr with the real local one.
 */

static inline void do_demasq(struct SheepVars *v, u8 *p)
{
        memcpy(p, v->eth_addr, 6);
}

static void demasquerade(struct SheepVars *v, struct sk_buff *skb)
{
        u8 *p = skb->mac.raw;
        int proto = (p[12] << 8) | p[13];
        
        do_demasq(v, p + 6); /* source address */

        /* Need to fix ARP packets */
        if (proto == ETH_P_ARP) {
                if (is_fake_addr(v, p + 14 + 8)) /* sender HW-addr */
                        do_demasq(v, p + 14 + 8);
        }

        /* ...and AARPs (snap code: 0x00,0x00,0x00,0x80,0xF3) */
        if (p[17] == 0 && p[18] == 0 && p[19] == 0 && p[20] == 0x80 && p[21] == 0xf3) {
                /* XXX: we should perhaps look for the 802 frame too */
                if (is_fake_addr(v, p + 30))
                        do_demasq(v, p + 30); /* sender HW-addr */
        }
}


/*
 * Incoming packet. Replace the local enet addr with the fake one.
 */

static inline void do_masq(struct SheepVars *v, u8 *p)
{
        memcpy(p, v->fake_addr, 6);
}

static void masquerade(struct SheepVars *v, struct sk_buff *skb)
{
        u8 *p = skb->mac.raw;
        if (!(p[0] & ETH_ADDR_MULTICAST))
                do_masq(v, p); /* destination address */

        /* XXX: reverse ARP might need to be fixed */
}


/*
 *  Driver read() function
 */

static ssize_t sheep_net_read(struct file *f, char *buf, size_t count, loff_t *off)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        struct sk_buff *skb;

        D(bug("sheep_net: read\n"));

        for (;;) {

                /* Get next packet from queue */
                skb = skb_dequeue(&v->queue);
                if (skb != NULL || (f->f_flags & O_NONBLOCK))
                        break;

                /* No packet in queue and in blocking mode, so block */
                interruptible_sleep_on(&v->wait);

                /* Signal received? Then bail out */
                if (signal_pending(current))
                        return -EINTR;
        }
        if (skb == NULL)
                return -EAGAIN;

        /* Pass packet to caller */
        if (count > skb->len)
                count = skb->len;
        if (copy_to_user(buf, skb->data, count))
                count = -EFAULT;
        dev_kfree_skb(skb);
        return count;
}


/*
 *  Driver write() function
 */

static ssize_t sheep_net_write(struct file *f, const char *buf, size_t count, loff_t *off)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        struct sk_buff *skb;
        char *p;
        D(bug("sheep_net: write\n"));

        /* Check packet size */
        if (count < sizeof(struct ethhdr))
                return -EINVAL;
        if (count > 1514)
                count = 1514;

        /* Interface active? */
        if (v->ether == NULL)
                return count;

        /* Allocate buffer for packet */
        skb = dev_alloc_skb(count);
        if (skb == NULL)
                return -ENOBUFS;

        /* Stuff packet in buffer */
        p = skb_put(skb, count);
        if (copy_from_user(p, buf, count)) {
                kfree_skb(skb);
                return -EFAULT;
        }

        /* Transmit packet */
        atomic_add(skb->truesize, &v->skt->wmem_alloc);
        skb->sk = v->skt;
        skb->dev = v->ether;
        skb->priority = 0;
        skb->nh.raw = skb->h.raw = skb->data + v->ether->hard_header_len;
        skb->mac.raw = skb->data;

        /* Base the IP-filtering on the IP address in any outgoing ARP packets */
        if (skb->mac.ethernet->h_proto == htons(ETH_P_ARP)) {
                u8 *p = &skb->data[14+14];      /* source IP address */
                u32 ip = (p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3];
                if (ip != v->ipfilter) {
                        v->ipfilter = ip;
                        printk("sheep_net: ipfilter set to %d.%d.%d.%d\n", (ip >> 24) & 0xff, (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
                }
        }

        /* Is this packet addressed solely to the local host? */
        if (is_local_addr(v, skb->data) && !(skb->data[0] & ETH_ADDR_MULTICAST)) {
                skb->protocol = eth_type_trans(skb, v->ether);
                netif_rx(skb);
                return count;
        }
        if (skb->data[0] & ETH_ADDR_MULTICAST) {
                /* We can't clone the skb since we will manipulate the data below */
                struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC);
                if (lskb) {
                        lskb->protocol = eth_type_trans(lskb, v->ether);
                        netif_rx(lskb);
                }
        }

        /* Outgoing packet (will be on the net) */
        demasquerade(v, skb);

        skb->protocol = PROT_MAGIC;     /* Magic value (we can recognize the packet in sheep_net_receiver) */
        dev_queue_xmit(skb);
        return count;
}


/*
 *  Driver poll() function
 */

static unsigned int sheep_net_poll(struct file *f, struct poll_table_struct *wait)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        D(bug("sheep_net: poll\n"));

        /* Packets in queue? Then return */
        if (!skb_queue_empty(&v->queue))
                return POLLIN | POLLRDNORM;

        /* Otherwise wait for packet */
        poll_wait(f, &v->wait, wait);
        if (!skb_queue_empty(&v->queue))
                return POLLIN | POLLRDNORM;
        else
                return 0;
}


/*
 *  Driver ioctl() function
 */

static int sheep_net_ioctl(struct inode *inode, struct file *f, unsigned int code, unsigned long arg)
{
        struct SheepVars *v = (struct SheepVars *)f->private_data;
        D(bug("sheep_net: ioctl %04x\n", code));

        switch (code) {

                /* Attach to Ethernet card
                   arg: pointer to name of Ethernet device (char[8]) */
                case SIOCSIFLINK: {
                        char name[8];
                        int err;

                        /* Already attached? */
                        if (v->ether)
                                return -EBUSY;

                        /* Get Ethernet card name */
                        if (copy_from_user(name, (void *)arg, 8))
                                return -EFAULT;
                        name[7] = 0;

                        /* Find card */
#ifdef LINUX_24
                        v->ether = dev_get_by_name(name);
#else
                        dev_lock_list();
                        v->ether = dev_get(name);
#endif
                        if (v->ether == NULL) {
                                err = -ENODEV;
                                goto error;
                        }

                        /* Is it Ethernet? */
                        if (v->ether->type != ARPHRD_ETHER) {
                                err = -EINVAL;
                                goto error;
                        }

                        /* Remember the card's hardware address */
                        memcpy(v->eth_addr, v->ether->dev_addr, 6);

                        /* Allocate socket */
                        v->skt = sk_alloc(0, GFP_USER, 1);
                        if (v->skt == NULL) {
                                err = -ENOMEM;
                                goto error;
                        }
                        v->skt->dead = 1;

                        /* Attach packet handler */
                        v->pt.type = htons(ETH_P_ALL);
                        v->pt.dev = v->ether;
                        v->pt.func = sheep_net_receiver;
                        v->pt.data = v;
                        dev_add_pack(&v->pt);
#ifndef LINUX_24
                        dev_unlock_list();
#endif
                        return 0;

error:
#ifdef LINUX_24
                        if (v->ether)
                                dev_put(v->ether);
#else
                        dev_unlock_list();
#endif
                        v->ether = NULL;
                        return err;
                }

                /* Get hardware address of the sheep_net module
                   arg: pointer to buffer (6 bytes) to store address */
                case SIOCGIFADDR:
                        if (copy_to_user((void *)arg, v->fake_addr, 6))
                                return -EFAULT;
                        return 0;

                /* Set the hardware address of the sheep_net module
                   arg: pointer to new address (6 bytes) */
                case SIOCSIFADDR:
                        if (copy_from_user(v->fake_addr, (void*)arg, 6))
                                return -EFAULT;
                        return 0;

                /* Add multicast address
                   arg: pointer to address (6 bytes) */
                case SIOCADDMULTI: {
                        char addr[6];
                        if (v->ether == NULL)
                                return -ENODEV;
                        if (copy_from_user(addr, (void *)arg, 6))
                                return -EFAULT;
                        return dev_mc_add(v->ether, addr, 6, 0);
                }

                /* Remove multicast address
                   arg: pointer to address (6 bytes) */
                case SIOCDELMULTI: {
                        char addr[6];
                        if (v->ether == NULL)
                                return -ENODEV;
                        if (copy_from_user(addr, (void *)arg, 6))
                                return -EFAULT;
                        return dev_mc_delete(v->ether, addr, 6, 0);
                }

                /* Return size of first packet in queue */
                case FIONREAD: {
                        int count = 0;
                        struct sk_buff *skb;
#ifdef LINUX_24
                        long flags;
                        spin_lock_irqsave(&v->queue.lock, flags);
#else
                        cli();
#endif
                        skb = skb_peek(&v->queue);
                        if (skb)
                                count = skb->len;
#ifdef LINUX_24
                        spin_unlock_irqrestore(&v->queue.lock, flags);
#else
                        sti();
#endif
                        return put_user(count, (int *)arg);
                }

                case SIOC_MOL_GET_IPFILTER:
                        return put_user(v->ipfilter, (int *)arg);

                case SIOC_MOL_SET_IPFILTER:
                        v->ipfilter = arg;
                        return 0;

                default:
                        return -ENOIOCTLCMD;
        }
}


/*
 *  Packet receiver function
 */

static int sheep_net_receiver(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt)
{
        struct SheepVars *v = (struct SheepVars *)pt->data;
        struct sk_buff *skb2;
        int fake;
        int multicast;
        D(bug("sheep_net: packet received\n"));

        multicast = (skb->mac.ethernet->h_dest[0] & ETH_ADDR_MULTICAST);
        fake = is_fake_addr(v, &skb->mac.ethernet->h_dest);

        /* Packet sent by us? Then discard */
        if (is_fake_addr(v, &skb->mac.ethernet->h_source) || skb->protocol == PROT_MAGIC)
                goto drop;

        /* If the packet is not meant for this host, discard it */
        if (!is_local_addr(v, &skb->mac.ethernet->h_dest) && !multicast && !fake)
                goto drop;

        /* Discard packets if queue gets too full */
        if (skb_queue_len(&v->queue) > MAX_QUEUE)
                goto drop;

        /* Apply any filters here (if fake is true, then we *know* we want this packet) */
        if (!fake) {
                if ((skb->protocol == htons(ETH_P_IP))
                 && (!v->ipfilter || (ntohl(skb->h.ipiph->daddr) != v->ipfilter && !multicast)))
                        goto drop;
        }

        /* Masquerade (we are typically a clone - best to make a real copy) */
        skb2 = skb_copy(skb, GFP_ATOMIC);
        if (!skb2)
                goto drop;
        kfree_skb(skb);
        skb = skb2;
        masquerade(v, skb);

        /* We also want the Ethernet header */
        skb_push(skb, skb->data - skb->mac.raw);

        /* Enqueue packet */
        skb_queue_tail(&v->queue, skb);

        /* Unblock blocked read */
        wake_up(&v->wait);
        return 0;

drop:
        kfree_skb(skb);
        return 0;
}
Revision:	1.4
Committed:	2001-03-18T15:41:17Z (23 years, 3 months ago) by cebix
Content type:	text/plain
Branch:	MAIN
Changes since 1.3:	+278 -112 lines
Log Message:	backported the changes from the Mac-On-Linux project: - now compiles under Linux 2.4 kernels - Ethernet hardware address is virtualized on the Mac side - automatically filters IP packets based on the IP address of the Mac side
#	Content
1	/*
2	* sheep_net.c - Linux driver for SheepShaver/Basilisk II networking (access to raw Ethernet packets)
3	*
4	* sheep_net (C) 1999-2001 Mar"c" Hellwig and Christian Bauer
5	*
6	* This program is free software; you can redistribute it and/or modify
7	* it under the terms of the GNU General Public License as published by
8	* the Free Software Foundation; either version 2 of the License, or
9	* (at your option) any later version.
10	*
11	* This program is distributed in the hope that it will be useful,
12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14	* GNU General Public License for more details.
15	*
16	* You should have received a copy of the GNU General Public License
17	* along with this program; if not, write to the Free Software
18	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19	*/
20
21	#include <linux/kernel.h>
22	#include <linux/module.h>
23	#include <linux/version.h>
24	#include <linux/miscdevice.h>
25	#include <linux/netdevice.h>
26	#include <linux/etherdevice.h>
27	#include <linux/if_ether.h>
28	#include <linux/if_arp.h>
29	#include <linux/fs.h>
30	#include <linux/poll.h>
31	#include <linux/init.h>
32	#include <linux/in.h>
33	#include <linux/wait.h>
34	#include <net/sock.h>
35	#include <net/arp.h>
36	#include <net/ip.h>
37	#include <asm/uaccess.h>
38
39	/* Compatibility glue */
40	#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
41	#define LINUX_24
42	#else
43	#define net_device device
44	typedef struct wait_queue *wait_queue_head_t;
45	#define init_waitqueue_head(x) *(x)=NULL
46	#endif
47
48	#define DEBUG 0
49
50	#define bug printk
51	#if DEBUG
52	#define D(x) (x);
53	#else
54	#define D(x) ;
55	#endif
56
57
58	/* Constants */
59	#define SHEEP_NET_MINOR 198 /* Driver minor number */
60	#define MAX_QUEUE 32 /* Maximum number of packets in queue */
61	#define PROT_MAGIC 1520 /* Our "magic" protocol type */
62
63	#define ETH_ADDR_MULTICAST 0x1
64
65	#define SIOC_MOL_GET_IPFILTER SIOCDEVPRIVATE
66	#define SIOC_MOL_SET_IPFILTER (SIOCDEVPRIVATE + 1)
67
68	/* Prototypes */
69	static int sheep_net_open(struct inode inode, struct file f);
70	static int sheep_net_release(struct inode inode, struct file f);
71	static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off);
72	static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off);
73	static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait);
74	static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg);
75	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt);
76
77
78	/*
79	* Driver private variables
80	*/
81
82	struct SheepVars {
83	struct net_device ether; / The Ethernet device we're attached to */
84	struct sock skt; / Socket for communication with Ethernet card */
85	struct sk_buff_head queue; /* Receiver packet queue */
86	struct packet_type pt; /* Receiver packet type */
87	wait_queue_head_t wait; /* Wait queue for blocking read operations */
88	u32 ipfilter; /* Only receive IP packets destined for this address (host byte order) */
89	char eth_addr[6]; /* Hardware address of the Ethernet card */
90	char fake_addr[6]; /* Local faked hardware address (what SheepShaver sees) */
91	};
92
93
94	/*
95	* file_operations structure - has function pointers to the
96	* various entry points for device operations
97	*/
98
99	static struct file_operations sheep_net_fops = {
100	read: sheep_net_read,
101	write: sheep_net_write,
102	poll: sheep_net_poll,
103	ioctl: sheep_net_ioctl,
104	open: sheep_net_open,
105	release: sheep_net_release,
106	};
107
108
109	/*
110	* miscdevice structure for driver initialization
111	*/
112
113	static struct miscdevice sheep_net_device = {
114	SHEEP_NET_MINOR, /* minor number */
115	"sheep_net", /* name */
116	&sheep_net_fops,
117	NULL,
118	NULL
119	};
120
121
122	/*
123	* Initialize module
124	*/
125
126	int init_module(void)
127	{
128	int ret;
129
130	/* Register driver */
131	ret = misc_register(&sheep_net_device);
132	D(bug("Sheep net driver installed\n"));
133	return ret;
134	}
135
136
137	/*
138	* Deinitialize module
139	*/
140
141	int cleanup_module(void)
142	{
143	int ret;
144
145	/* Unregister driver */
146	ret = misc_deregister(&sheep_net_device);
147	D(bug("Sheep net driver removed\n"));
148	return ret;
149	}
150
151
152	/*
153	* Driver open() function
154	*/
155
156	static int sheep_net_open(struct inode inode, struct file f)
157	{
158	struct SheepVars *v;
159	D(bug("sheep_net: open\n"));
160
161	/* Must be opened with read permissions */
162	if ((f->f_flags & O_ACCMODE) == O_WRONLY)
163	return -EPERM;
164
165	/* Allocate private variables */
166	v = (struct SheepVars *)f->private_data = kmalloc(sizeof(struct SheepVars), GFP_USER);
167	if (v == NULL)
168	return -ENOMEM;
169	memset(v, 0, sizeof(struct SheepVars));
170	skb_queue_head_init(&v->queue);
171	init_waitqueue_head(&v->wait);
172	v->fake_addr[0] = 0xfe;
173	v->fake_addr[1] = 0xfd;
174	v->fake_addr[2] = 0xde;
175	v->fake_addr[3] = 0xad;
176	v->fake_addr[4] = 0xbe;
177	v->fake_addr[5] = 0xef;
178
179	/* Yes, we're open */
180	MOD_INC_USE_COUNT;
181	return 0;
182	}
183
184
185	/*
186	* Driver release() function
187	*/
188
189	static int sheep_net_release(struct inode inode, struct file f)
190	{
191	struct SheepVars v = (struct SheepVars )f->private_data;
192	struct sk_buff *skb;
193	D(bug("sheep_net: close\n"));
194
195	/* Detach from Ethernet card */
196	if (v->ether) {
197	dev_remove_pack(&v->pt);
198	sk_free(v->skt);
199	v->skt = NULL;
200	#ifdef LINUX_24
201	dev_put( v->ether );
202	#endif
203	v->ether = NULL;
204	}
205
206	/* Empty packet queue */
207	while ((skb = skb_dequeue(&v->queue)) != NULL)
208	dev_kfree_skb(skb);
209
210	/* Free private variables */
211	kfree(v);
212
213	/* Sorry, we're closed */
214	MOD_DEC_USE_COUNT;
215	return 0;
216	}
217
218
219	/*
220	* Check whether an Ethernet address is the local (attached) one or
221	* the fake one
222	*/
223
224	static inline int is_local_addr(struct SheepVars v, void a)
225	{
226	return memcmp(a, v->eth_addr, 6) == 0;
227	}
228
229	static inline int is_fake_addr(struct SheepVars v, void a)
230	{
231	return memcmp(a, v->fake_addr, 6) == 0;
232	}
233
234
235	/*
236	* Outgoing packet. Replace the fake enet addr with the real local one.
237	*/
238
239	static inline void do_demasq(struct SheepVars v, u8 p)
240	{
241	memcpy(p, v->eth_addr, 6);
242	}
243
244	static void demasquerade(struct SheepVars v, struct sk_buff skb)
245	{
246	u8 *p = skb->mac.raw;
247	int proto = (p[12] << 8) \| p[13];
248
249	do_demasq(v, p + 6); /* source address */
250
251	/* Need to fix ARP packets */
252	if (proto == ETH_P_ARP) {
253	if (is_fake_addr(v, p + 14 + 8)) /* sender HW-addr */
254	do_demasq(v, p + 14 + 8);
255	}
256
257	/* ...and AARPs (snap code: 0x00,0x00,0x00,0x80,0xF3) */
258	if (p[17] == 0 && p[18] == 0 && p[19] == 0 && p[20] == 0x80 && p[21] == 0xf3) {
259	/* XXX: we should perhaps look for the 802 frame too */
260	if (is_fake_addr(v, p + 30))
261	do_demasq(v, p + 30); /* sender HW-addr */
262	}
263	}
264
265
266	/*
267	* Incoming packet. Replace the local enet addr with the fake one.
268	*/
269
270	static inline void do_masq(struct SheepVars v, u8 p)
271	{
272	memcpy(p, v->fake_addr, 6);
273	}
274
275	static void masquerade(struct SheepVars v, struct sk_buff skb)
276	{
277	u8 *p = skb->mac.raw;
278	if (!(p[0] & ETH_ADDR_MULTICAST))
279	do_masq(v, p); /* destination address */
280
281	/* XXX: reverse ARP might need to be fixed */
282	}
283
284
285	/*
286	* Driver read() function
287	*/
288
289	static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off)
290	{
291	struct SheepVars v = (struct SheepVars )f->private_data;
292	struct sk_buff *skb;
293
294	D(bug("sheep_net: read\n"));
295
296	for (;;) {
297
298	/* Get next packet from queue */
299	skb = skb_dequeue(&v->queue);
300	if (skb != NULL \|\| (f->f_flags & O_NONBLOCK))
301	break;
302
303	/* No packet in queue and in blocking mode, so block */
304	interruptible_sleep_on(&v->wait);
305
306	/* Signal received? Then bail out */
307	if (signal_pending(current))
308	return -EINTR;
309	}
310	if (skb == NULL)
311	return -EAGAIN;
312
313	/* Pass packet to caller */
314	if (count > skb->len)
315	count = skb->len;
316	if (copy_to_user(buf, skb->data, count))
317	count = -EFAULT;
318	dev_kfree_skb(skb);
319	return count;
320	}
321
322
323	/*
324	* Driver write() function
325	*/
326
327	static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off)
328	{
329	struct SheepVars v = (struct SheepVars )f->private_data;
330	struct sk_buff *skb;
331	char *p;
332	D(bug("sheep_net: write\n"));
333
334	/* Check packet size */
335	if (count < sizeof(struct ethhdr))
336	return -EINVAL;
337	if (count > 1514)
338	count = 1514;
339
340	/* Interface active? */
341	if (v->ether == NULL)
342	return count;
343
344	/* Allocate buffer for packet */
345	skb = dev_alloc_skb(count);
346	if (skb == NULL)
347	return -ENOBUFS;
348
349	/* Stuff packet in buffer */
350	p = skb_put(skb, count);
351	if (copy_from_user(p, buf, count)) {
352	kfree_skb(skb);
353	return -EFAULT;
354	}
355
356	/* Transmit packet */
357	atomic_add(skb->truesize, &v->skt->wmem_alloc);
358	skb->sk = v->skt;
359	skb->dev = v->ether;
360	skb->priority = 0;
361	skb->nh.raw = skb->h.raw = skb->data + v->ether->hard_header_len;
362	skb->mac.raw = skb->data;
363
364	/* Base the IP-filtering on the IP address in any outgoing ARP packets */
365	if (skb->mac.ethernet->h_proto == htons(ETH_P_ARP)) {
366	u8 p = &skb->data[14+14]; / source IP address */
367	u32 ip = (p[0] << 24) \| (p[1] << 16) \| (p[2] << 8) \| p[3];
368	if (ip != v->ipfilter) {
369	v->ipfilter = ip;
370	printk("sheep_net: ipfilter set to %d.%d.%d.%d\n", (ip >> 24) & 0xff, (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
371	}
372	}
373
374	/* Is this packet addressed solely to the local host? */
375	if (is_local_addr(v, skb->data) && !(skb->data[0] & ETH_ADDR_MULTICAST)) {
376	skb->protocol = eth_type_trans(skb, v->ether);
377	netif_rx(skb);
378	return count;
379	}
380	if (skb->data[0] & ETH_ADDR_MULTICAST) {
381	/* We can't clone the skb since we will manipulate the data below */
382	struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC);
383	if (lskb) {
384	lskb->protocol = eth_type_trans(lskb, v->ether);
385	netif_rx(lskb);
386	}
387	}
388
389	/* Outgoing packet (will be on the net) */
390	demasquerade(v, skb);
391
392	skb->protocol = PROT_MAGIC; /* Magic value (we can recognize the packet in sheep_net_receiver) */
393	dev_queue_xmit(skb);
394	return count;
395	}
396
397
398	/*
399	* Driver poll() function
400	*/
401
402	static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait)
403	{
404	struct SheepVars v = (struct SheepVars )f->private_data;
405	D(bug("sheep_net: poll\n"));
406
407	/* Packets in queue? Then return */
408	if (!skb_queue_empty(&v->queue))
409	return POLLIN \| POLLRDNORM;
410
411	/* Otherwise wait for packet */
412	poll_wait(f, &v->wait, wait);
413	if (!skb_queue_empty(&v->queue))
414	return POLLIN \| POLLRDNORM;
415	else
416	return 0;
417	}
418
419
420	/*
421	* Driver ioctl() function
422	*/
423
424	static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg)
425	{
426	struct SheepVars v = (struct SheepVars )f->private_data;
427	D(bug("sheep_net: ioctl %04x\n", code));
428
429	switch (code) {
430
431	/* Attach to Ethernet card
432	arg: pointer to name of Ethernet device (char[8]) */
433	case SIOCSIFLINK: {
434	char name[8];
435	int err;
436
437	/* Already attached? */
438	if (v->ether)
439	return -EBUSY;
440
441	/* Get Ethernet card name */
442	if (copy_from_user(name, (void *)arg, 8))
443	return -EFAULT;
444	name[7] = 0;
445
446	/* Find card */
447	#ifdef LINUX_24
448	v->ether = dev_get_by_name(name);
449	#else
450	dev_lock_list();
451	v->ether = dev_get(name);
452	#endif
453	if (v->ether == NULL) {
454	err = -ENODEV;
455	goto error;
456	}
457
458	/* Is it Ethernet? */
459	if (v->ether->type != ARPHRD_ETHER) {
460	err = -EINVAL;
461	goto error;
462	}
463
464	/* Remember the card's hardware address */
465	memcpy(v->eth_addr, v->ether->dev_addr, 6);
466
467	/* Allocate socket */
468	v->skt = sk_alloc(0, GFP_USER, 1);
469	if (v->skt == NULL) {
470	err = -ENOMEM;
471	goto error;
472	}
473	v->skt->dead = 1;
474
475	/* Attach packet handler */
476	v->pt.type = htons(ETH_P_ALL);
477	v->pt.dev = v->ether;
478	v->pt.func = sheep_net_receiver;
479	v->pt.data = v;
480	dev_add_pack(&v->pt);
481	#ifndef LINUX_24
482	dev_unlock_list();
483	#endif
484	return 0;
485
486	error:
487	#ifdef LINUX_24
488	if (v->ether)
489	dev_put(v->ether);
490	#else
491	dev_unlock_list();
492	#endif
493	v->ether = NULL;
494	return err;
495	}
496
497	/* Get hardware address of the sheep_net module
498	arg: pointer to buffer (6 bytes) to store address */
499	case SIOCGIFADDR:
500	if (copy_to_user((void *)arg, v->fake_addr, 6))
501	return -EFAULT;
502	return 0;
503
504	/* Set the hardware address of the sheep_net module
505	arg: pointer to new address (6 bytes) */
506	case SIOCSIFADDR:
507	if (copy_from_user(v->fake_addr, (void*)arg, 6))
508	return -EFAULT;
509	return 0;
510
511	/* Add multicast address
512	arg: pointer to address (6 bytes) */
513	case SIOCADDMULTI: {
514	char addr[6];
515	if (v->ether == NULL)
516	return -ENODEV;
517	if (copy_from_user(addr, (void *)arg, 6))
518	return -EFAULT;
519	return dev_mc_add(v->ether, addr, 6, 0);
520	}
521
522	/* Remove multicast address
523	arg: pointer to address (6 bytes) */
524	case SIOCDELMULTI: {
525	char addr[6];
526	if (v->ether == NULL)
527	return -ENODEV;
528	if (copy_from_user(addr, (void *)arg, 6))
529	return -EFAULT;
530	return dev_mc_delete(v->ether, addr, 6, 0);
531	}
532
533	/* Return size of first packet in queue */
534	case FIONREAD: {
535	int count = 0;
536	struct sk_buff *skb;
537	#ifdef LINUX_24
538	long flags;
539	spin_lock_irqsave(&v->queue.lock, flags);
540	#else
541	cli();
542	#endif
543	skb = skb_peek(&v->queue);
544	if (skb)
545	count = skb->len;
546	#ifdef LINUX_24
547	spin_unlock_irqrestore(&v->queue.lock, flags);
548	#else
549	sti();
550	#endif
551	return put_user(count, (int *)arg);
552	}
553
554	case SIOC_MOL_GET_IPFILTER:
555	return put_user(v->ipfilter, (int *)arg);
556
557	case SIOC_MOL_SET_IPFILTER:
558	v->ipfilter = arg;
559	return 0;
560
561	default:
562	return -ENOIOCTLCMD;
563	}
564	}
565
566
567	/*
568	* Packet receiver function
569	*/
570
571	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt)
572	{
573	struct SheepVars v = (struct SheepVars )pt->data;
574	struct sk_buff *skb2;
575	int fake;
576	int multicast;
577	D(bug("sheep_net: packet received\n"));
578
579	multicast = (skb->mac.ethernet->h_dest[0] & ETH_ADDR_MULTICAST);
580	fake = is_fake_addr(v, &skb->mac.ethernet->h_dest);
581
582	/* Packet sent by us? Then discard */
583	if (is_fake_addr(v, &skb->mac.ethernet->h_source) \|\| skb->protocol == PROT_MAGIC)
584	goto drop;
585
586	/* If the packet is not meant for this host, discard it */
587	if (!is_local_addr(v, &skb->mac.ethernet->h_dest) && !multicast && !fake)
588	goto drop;
589
590	/* Discard packets if queue gets too full */
591	if (skb_queue_len(&v->queue) > MAX_QUEUE)
592	goto drop;
593
594	/* Apply any filters here (if fake is true, then we know we want this packet) */
595	if (!fake) {
596	if ((skb->protocol == htons(ETH_P_IP))
597	&& (!v->ipfilter \|\| (ntohl(skb->h.ipiph->daddr) != v->ipfilter && !multicast)))
598	goto drop;
599	}
600
601	/* Masquerade (we are typically a clone - best to make a real copy) */
602	skb2 = skb_copy(skb, GFP_ATOMIC);
603	if (!skb2)
604	goto drop;
605	kfree_skb(skb);
606	skb = skb2;
607	masquerade(v, skb);
608
609	/* We also want the Ethernet header */
610	skb_push(skb, skb->data - skb->mac.raw);
611
612	/* Enqueue packet */
613	skb_queue_tail(&v->queue, skb);
614
615	/* Unblock blocked read */
616	wake_up(&v->wait);
617	return 0;
618
619	drop:
620	kfree_skb(skb);
621	return 0;
622	}