Linux/NetDriver/sheep_net.c

/*
 *  sheep_net.c - Linux driver for SheepShaver/Basilisk II networking (access to raw Ethernet packets)
 *
 *  sheep_net (C) 1999-2002 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
 */

#ifndef __KERNEL__
#define __KERNEL__
#endif

#ifndef MODULE
#define MODULE
#endif

/* determine whether to use checksummed versions of kernel symbols */
#include <linux/config.h>
#ifdef CONFIG_MODVERSIONS
#define MODVERSIONS
#include <linux/modversions.h>
#endif

/* modversions.h redefines kernel symbols.  Now include other headers */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>

#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 <net/sock.h>
#include <asm/uaccess.h>
#include <net/arp.h>
#include <net/ip.h>
#include <linux/in.h>
#include <linux/wait.h>

MODULE_AUTHOR("Christian Bauer");
MODULE_DESCRIPTION("Pseudo ethernet device for emulators");

/* 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 ETH_ADDR_LOCALLY_DEFINED 0x02

#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) {
                printk("sheep_net_write: packet size > 1514\n");
                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[20]) */
                case SIOCSIFLINK: {
                        char name[20];
                        int err;

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

                        /* Get Ethernet card name */
                        if (copy_from_user(name, (void *)arg, 20))
                                return -EFAULT;
                        name[19] = 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;
}

MODULE_LICENSE("GPL");
Revision:	1.9
Committed:	2002-07-23T18:02:47Z (21 years, 11 months ago) by cebix
Content type:	text/plain
Branch:	MAIN
Changes since 1.8:	+22 -0 lines
Log Message:	fixes by Steven N. Hirsch (versioned symbols, module license)
#	User	Rev	Content
1	cebix	1.1	/*
2			* sheep_net.c - Linux driver for SheepShaver/Basilisk II networking (access to raw Ethernet packets)
3			*
4	cebix	1.8	* sheep_net (C) 1999-2002 Mar"c" Hellwig and Christian Bauer
5	cebix	1.1	*
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	cebix	1.9	#ifndef __KERNEL__
22			#define __KERNEL__
23			#endif
24
25			#ifndef MODULE
26			#define MODULE
27			#endif
28
29			/* determine whether to use checksummed versions of kernel symbols */
30			#include <linux/config.h>
31			#ifdef CONFIG_MODVERSIONS
32			#define MODVERSIONS
33			#include <linux/modversions.h>
34			#endif
35
36			/* modversions.h redefines kernel symbols. Now include other headers */
37			#include <linux/kernel.h>
38			#include <linux/module.h>
39			#include <linux/init.h>
40
41	cebix	1.7	#include <linux/kernel.h>
42	cebix	1.1	#include <linux/module.h>
43			#include <linux/version.h>
44			#include <linux/miscdevice.h>
45			#include <linux/netdevice.h>
46			#include <linux/etherdevice.h>
47			#include <linux/if_ether.h>
48			#include <linux/if_arp.h>
49	cebix	1.7	#include <linux/fs.h>
50	cebix	1.1	#include <linux/poll.h>
51			#include <linux/init.h>
52			#include <net/sock.h>
53	cebix	1.7	#include <asm/uaccess.h>
54	cebix	1.4	#include <net/arp.h>
55			#include <net/ip.h>
56	cebix	1.7	#include <linux/in.h>
57			#include <linux/wait.h>
58	cebix	1.1
59	cebix	1.5	MODULE_AUTHOR("Christian Bauer");
60			MODULE_DESCRIPTION("Pseudo ethernet device for emulators");
61
62	cebix	1.4	/* Compatibility glue */
63			#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
64			#define LINUX_24
65			#else
66			#define net_device device
67			typedef struct wait_queue *wait_queue_head_t;
68			#define init_waitqueue_head(x) *(x)=NULL
69			#endif
70
71	cebix	1.1	#define DEBUG 0
72
73			#define bug printk
74			#if DEBUG
75			#define D(x) (x);
76			#else
77			#define D(x) ;
78			#endif
79
80
81	cebix	1.4	/* Constants */
82			#define SHEEP_NET_MINOR 198 /* Driver minor number */
83			#define MAX_QUEUE 32 /* Maximum number of packets in queue */
84			#define PROT_MAGIC 1520 /* Our "magic" protocol type */
85	cebix	1.1
86	cebix	1.4	#define ETH_ADDR_MULTICAST 0x1
87	cebix	1.7	#define ETH_ADDR_LOCALLY_DEFINED 0x02
88	cebix	1.4
89			#define SIOC_MOL_GET_IPFILTER SIOCDEVPRIVATE
90			#define SIOC_MOL_SET_IPFILTER (SIOCDEVPRIVATE + 1)
91
92			/* Prototypes */
93	cebix	1.1	static int sheep_net_open(struct inode inode, struct file f);
94			static int sheep_net_release(struct inode inode, struct file f);
95			static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off);
96			static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off);
97			static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait);
98			static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg);
99	cebix	1.4	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt);
100	cebix	1.1
101
102			/*
103			* Driver private variables
104			*/
105
106			struct SheepVars {
107	cebix	1.4	struct net_device ether; / The Ethernet device we're attached to */
108			struct sock skt; / Socket for communication with Ethernet card */
109			struct sk_buff_head queue; /* Receiver packet queue */
110			struct packet_type pt; /* Receiver packet type */
111			wait_queue_head_t wait; /* Wait queue for blocking read operations */
112			u32 ipfilter; /* Only receive IP packets destined for this address (host byte order) */
113			char eth_addr[6]; /* Hardware address of the Ethernet card */
114			char fake_addr[6]; /* Local faked hardware address (what SheepShaver sees) */
115	cebix	1.1	};
116
117
118			/*
119			* file_operations structure - has function pointers to the
120			* various entry points for device operations
121			*/
122
123			static struct file_operations sheep_net_fops = {
124	cebix	1.4	read: sheep_net_read,
125			write: sheep_net_write,
126			poll: sheep_net_poll,
127			ioctl: sheep_net_ioctl,
128			open: sheep_net_open,
129			release: sheep_net_release,
130	cebix	1.1	};
131
132
133			/*
134			* miscdevice structure for driver initialization
135			*/
136
137			static struct miscdevice sheep_net_device = {
138	cebix	1.4	SHEEP_NET_MINOR, /* minor number */
139			"sheep_net", /* name */
140	cebix	1.1	&sheep_net_fops,
141			NULL,
142			NULL
143			};
144
145
146			/*
147			* Initialize module
148			*/
149
150			int init_module(void)
151			{
152			int ret;
153
154	cebix	1.4	/* Register driver */
155	cebix	1.1	ret = misc_register(&sheep_net_device);
156			D(bug("Sheep net driver installed\n"));
157			return ret;
158			}
159
160
161			/*
162			* Deinitialize module
163			*/
164
165	cebix	1.7	int cleanup_module(void)
166	cebix	1.1	{
167	cebix	1.7	int ret;
168
169	cebix	1.4	/* Unregister driver */
170	cebix	1.7	ret = misc_deregister(&sheep_net_device);
171	cebix	1.1	D(bug("Sheep net driver removed\n"));
172	cebix	1.7	return ret;
173	cebix	1.1	}
174
175
176			/*
177			* Driver open() function
178			*/
179
180			static int sheep_net_open(struct inode inode, struct file f)
181			{
182			struct SheepVars *v;
183			D(bug("sheep_net: open\n"));
184
185	cebix	1.4	/* Must be opened with read permissions */
186	cebix	1.1	if ((f->f_flags & O_ACCMODE) == O_WRONLY)
187			return -EPERM;
188
189	cebix	1.4	/* Allocate private variables */
190	cebix	1.1	v = (struct SheepVars *)f->private_data = kmalloc(sizeof(struct SheepVars), GFP_USER);
191			if (v == NULL)
192			return -ENOMEM;
193			memset(v, 0, sizeof(struct SheepVars));
194			skb_queue_head_init(&v->queue);
195	cebix	1.4	init_waitqueue_head(&v->wait);
196			v->fake_addr[0] = 0xfe;
197			v->fake_addr[1] = 0xfd;
198			v->fake_addr[2] = 0xde;
199			v->fake_addr[3] = 0xad;
200			v->fake_addr[4] = 0xbe;
201			v->fake_addr[5] = 0xef;
202	cebix	1.1
203	cebix	1.4	/* Yes, we're open */
204	cebix	1.1	MOD_INC_USE_COUNT;
205			return 0;
206			}
207
208
209			/*
210			* Driver release() function
211			*/
212
213			static int sheep_net_release(struct inode inode, struct file f)
214			{
215			struct SheepVars v = (struct SheepVars )f->private_data;
216			struct sk_buff *skb;
217			D(bug("sheep_net: close\n"));
218
219	cebix	1.4	/* Detach from Ethernet card */
220	cebix	1.1	if (v->ether) {
221			dev_remove_pack(&v->pt);
222			sk_free(v->skt);
223			v->skt = NULL;
224	cebix	1.4	#ifdef LINUX_24
225			dev_put( v->ether );
226			#endif
227	cebix	1.1	v->ether = NULL;
228			}
229
230	cebix	1.4	/* Empty packet queue */
231	cebix	1.1	while ((skb = skb_dequeue(&v->queue)) != NULL)
232			dev_kfree_skb(skb);
233
234	cebix	1.4	/* Free private variables */
235	cebix	1.1	kfree(v);
236
237	cebix	1.4	/* Sorry, we're closed */
238	cebix	1.1	MOD_DEC_USE_COUNT;
239			return 0;
240			}
241
242
243			/*
244	cebix	1.4	* Check whether an Ethernet address is the local (attached) one or
245			* the fake one
246			*/
247
248			static inline int is_local_addr(struct SheepVars v, void a)
249			{
250			return memcmp(a, v->eth_addr, 6) == 0;
251			}
252
253			static inline int is_fake_addr(struct SheepVars v, void a)
254			{
255			return memcmp(a, v->fake_addr, 6) == 0;
256			}
257
258
259			/*
260			* Outgoing packet. Replace the fake enet addr with the real local one.
261			*/
262
263			static inline void do_demasq(struct SheepVars v, u8 p)
264			{
265			memcpy(p, v->eth_addr, 6);
266			}
267
268			static void demasquerade(struct SheepVars v, struct sk_buff skb)
269			{
270			u8 *p = skb->mac.raw;
271			int proto = (p[12] << 8) \| p[13];
272
273			do_demasq(v, p + 6); /* source address */
274
275			/* Need to fix ARP packets */
276			if (proto == ETH_P_ARP) {
277			if (is_fake_addr(v, p + 14 + 8)) /* sender HW-addr */
278			do_demasq(v, p + 14 + 8);
279			}
280
281			/* ...and AARPs (snap code: 0x00,0x00,0x00,0x80,0xF3) */
282			if (p[17] == 0 && p[18] == 0 && p[19] == 0 && p[20] == 0x80 && p[21] == 0xf3) {
283			/* XXX: we should perhaps look for the 802 frame too */
284			if (is_fake_addr(v, p + 30))
285			do_demasq(v, p + 30); /* sender HW-addr */
286			}
287			}
288
289
290			/*
291			* Incoming packet. Replace the local enet addr with the fake one.
292			*/
293
294			static inline void do_masq(struct SheepVars v, u8 p)
295			{
296			memcpy(p, v->fake_addr, 6);
297			}
298
299			static void masquerade(struct SheepVars v, struct sk_buff skb)
300			{
301			u8 *p = skb->mac.raw;
302			if (!(p[0] & ETH_ADDR_MULTICAST))
303			do_masq(v, p); /* destination address */
304
305			/* XXX: reverse ARP might need to be fixed */
306			}
307
308
309			/*
310	cebix	1.1	* Driver read() function
311			*/
312
313			static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off)
314			{
315			struct SheepVars v = (struct SheepVars )f->private_data;
316			struct sk_buff *skb;
317	cebix	1.4
318	cebix	1.1	D(bug("sheep_net: read\n"));
319
320			for (;;) {
321
322	cebix	1.4	/* Get next packet from queue */
323	cebix	1.1	skb = skb_dequeue(&v->queue);
324			if (skb != NULL \|\| (f->f_flags & O_NONBLOCK))
325			break;
326
327	cebix	1.4	/* No packet in queue and in blocking mode, so block */
328	cebix	1.1	interruptible_sleep_on(&v->wait);
329
330	cebix	1.4	/* Signal received? Then bail out */
331			if (signal_pending(current))
332			return -EINTR;
333	cebix	1.1	}
334			if (skb == NULL)
335			return -EAGAIN;
336
337	cebix	1.4	/* Pass packet to caller */
338	cebix	1.1	if (count > skb->len)
339			count = skb->len;
340			if (copy_to_user(buf, skb->data, count))
341			count = -EFAULT;
342			dev_kfree_skb(skb);
343			return count;
344			}
345
346
347			/*
348			* Driver write() function
349			*/
350
351			static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off)
352			{
353			struct SheepVars v = (struct SheepVars )f->private_data;
354			struct sk_buff *skb;
355			char *p;
356			D(bug("sheep_net: write\n"));
357
358	cebix	1.4	/* Check packet size */
359	cebix	1.1	if (count < sizeof(struct ethhdr))
360			return -EINVAL;
361	cebix	1.7	if (count > 1514) {
362			printk("sheep_net_write: packet size > 1514\n");
363	cebix	1.1	count = 1514;
364	cebix	1.7	}
365	cebix	1.1
366	cebix	1.4	/* Interface active? */
367	cebix	1.1	if (v->ether == NULL)
368			return count;
369
370	cebix	1.4	/* Allocate buffer for packet */
371	cebix	1.1	skb = dev_alloc_skb(count);
372			if (skb == NULL)
373			return -ENOBUFS;
374
375	cebix	1.4	/* Stuff packet in buffer */
376	cebix	1.1	p = skb_put(skb, count);
377			if (copy_from_user(p, buf, count)) {
378			kfree_skb(skb);
379			return -EFAULT;
380			}
381
382	cebix	1.4	/* Transmit packet */
383	cebix	1.1	atomic_add(skb->truesize, &v->skt->wmem_alloc);
384			skb->sk = v->skt;
385			skb->dev = v->ether;
386			skb->priority = 0;
387			skb->nh.raw = skb->h.raw = skb->data + v->ether->hard_header_len;
388	cebix	1.4	skb->mac.raw = skb->data;
389
390			/* Base the IP-filtering on the IP address in any outgoing ARP packets */
391			if (skb->mac.ethernet->h_proto == htons(ETH_P_ARP)) {
392			u8 p = &skb->data[14+14]; / source IP address */
393			u32 ip = (p[0] << 24) \| (p[1] << 16) \| (p[2] << 8) \| p[3];
394			if (ip != v->ipfilter) {
395			v->ipfilter = ip;
396			printk("sheep_net: ipfilter set to %d.%d.%d.%d\n", (ip >> 24) & 0xff, (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
397			}
398			}
399
400			/* Is this packet addressed solely to the local host? */
401			if (is_local_addr(v, skb->data) && !(skb->data[0] & ETH_ADDR_MULTICAST)) {
402			skb->protocol = eth_type_trans(skb, v->ether);
403			netif_rx(skb);
404			return count;
405			}
406			if (skb->data[0] & ETH_ADDR_MULTICAST) {
407			/* We can't clone the skb since we will manipulate the data below */
408			struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC);
409			if (lskb) {
410			lskb->protocol = eth_type_trans(lskb, v->ether);
411			netif_rx(lskb);
412			}
413			}
414
415			/* Outgoing packet (will be on the net) */
416			demasquerade(v, skb);
417
418			skb->protocol = PROT_MAGIC; /* Magic value (we can recognize the packet in sheep_net_receiver) */
419	cebix	1.1	dev_queue_xmit(skb);
420			return count;
421			}
422
423
424			/*
425			* Driver poll() function
426			*/
427
428			static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait)
429			{
430			struct SheepVars v = (struct SheepVars )f->private_data;
431			D(bug("sheep_net: poll\n"));
432
433	cebix	1.4	/* Packets in queue? Then return */
434			if (!skb_queue_empty(&v->queue))
435	cebix	1.1	return POLLIN \| POLLRDNORM;
436
437	cebix	1.4	/* Otherwise wait for packet */
438	cebix	1.1	poll_wait(f, &v->wait, wait);
439	cebix	1.4	if (!skb_queue_empty(&v->queue))
440	cebix	1.1	return POLLIN \| POLLRDNORM;
441	cebix	1.4	else
442	cebix	1.1	return 0;
443			}
444
445
446			/*
447			* Driver ioctl() function
448			*/
449
450			static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg)
451			{
452			struct SheepVars v = (struct SheepVars )f->private_data;
453			D(bug("sheep_net: ioctl %04x\n", code));
454
455			switch (code) {
456
457	cebix	1.4	/* Attach to Ethernet card
458	cebix	1.7	arg: pointer to name of Ethernet device (char[20]) */
459	cebix	1.1	case SIOCSIFLINK: {
460	cebix	1.7	char name[20];
461	cebix	1.4	int err;
462	cebix	1.1
463	cebix	1.4	/* Already attached? */
464	cebix	1.1	if (v->ether)
465			return -EBUSY;
466
467	cebix	1.4	/* Get Ethernet card name */
468	cebix	1.7	if (copy_from_user(name, (void *)arg, 20))
469	cebix	1.1	return -EFAULT;
470	cebix	1.7	name[19] = 0;
471	cebix	1.1
472	cebix	1.4	/* Find card */
473			#ifdef LINUX_24
474			v->ether = dev_get_by_name(name);
475			#else
476	cebix	1.1	dev_lock_list();
477			v->ether = dev_get(name);
478	cebix	1.4	#endif
479	cebix	1.1	if (v->ether == NULL) {
480	cebix	1.4	err = -ENODEV;
481			goto error;
482	cebix	1.1	}
483
484	cebix	1.4	/* Is it Ethernet? */
485	cebix	1.1	if (v->ether->type != ARPHRD_ETHER) {
486	cebix	1.4	err = -EINVAL;
487			goto error;
488	cebix	1.1	}
489
490	cebix	1.4	/* Remember the card's hardware address */
491			memcpy(v->eth_addr, v->ether->dev_addr, 6);
492
493			/* Allocate socket */
494	cebix	1.1	v->skt = sk_alloc(0, GFP_USER, 1);
495			if (v->skt == NULL) {
496	cebix	1.4	err = -ENOMEM;
497			goto error;
498	cebix	1.1	}
499			v->skt->dead = 1;
500
501	cebix	1.4	/* Attach packet handler */
502	cebix	1.1	v->pt.type = htons(ETH_P_ALL);
503			v->pt.dev = v->ether;
504			v->pt.func = sheep_net_receiver;
505			v->pt.data = v;
506			dev_add_pack(&v->pt);
507	cebix	1.4	#ifndef LINUX_24
508	cebix	1.1	dev_unlock_list();
509	cebix	1.4	#endif
510	cebix	1.1	return 0;
511	cebix	1.4
512			error:
513			#ifdef LINUX_24
514			if (v->ether)
515			dev_put(v->ether);
516			#else
517			dev_unlock_list();
518			#endif
519			v->ether = NULL;
520			return err;
521	cebix	1.1	}
522
523	cebix	1.4	/* Get hardware address of the sheep_net module
524			arg: pointer to buffer (6 bytes) to store address */
525	cebix	1.1	case SIOCGIFADDR:
526	cebix	1.4	if (copy_to_user((void *)arg, v->fake_addr, 6))
527			return -EFAULT;
528			return 0;
529
530			/* Set the hardware address of the sheep_net module
531			arg: pointer to new address (6 bytes) */
532			case SIOCSIFADDR:
533			if (copy_from_user(v->fake_addr, (void*)arg, 6))
534	cebix	1.1	return -EFAULT;
535			return 0;
536
537	cebix	1.4	/* Add multicast address
538			arg: pointer to address (6 bytes) */
539	cebix	1.1	case SIOCADDMULTI: {
540			char addr[6];
541			if (v->ether == NULL)
542			return -ENODEV;
543			if (copy_from_user(addr, (void *)arg, 6))
544			return -EFAULT;
545			return dev_mc_add(v->ether, addr, 6, 0);
546			}
547
548	cebix	1.4	/* Remove multicast address
549			arg: pointer to address (6 bytes) */
550	cebix	1.1	case SIOCDELMULTI: {
551			char addr[6];
552			if (v->ether == NULL)
553			return -ENODEV;
554			if (copy_from_user(addr, (void *)arg, 6))
555			return -EFAULT;
556			return dev_mc_delete(v->ether, addr, 6, 0);
557			}
558
559	cebix	1.4	/* Return size of first packet in queue */
560	cebix	1.1	case FIONREAD: {
561			int count = 0;
562			struct sk_buff *skb;
563	cebix	1.4	#ifdef LINUX_24
564			long flags;
565			spin_lock_irqsave(&v->queue.lock, flags);
566			#else
567			cli();
568			#endif
569	cebix	1.1	skb = skb_peek(&v->queue);
570			if (skb)
571			count = skb->len;
572	cebix	1.4	#ifdef LINUX_24
573			spin_unlock_irqrestore(&v->queue.lock, flags);
574			#else
575			sti();
576			#endif
577	cebix	1.1	return put_user(count, (int *)arg);
578			}
579
580	cebix	1.4	case SIOC_MOL_GET_IPFILTER:
581			return put_user(v->ipfilter, (int *)arg);
582
583			case SIOC_MOL_SET_IPFILTER:
584			v->ipfilter = arg;
585			return 0;
586
587	cebix	1.1	default:
588			return -ENOIOCTLCMD;
589			}
590			}
591
592
593			/*
594			* Packet receiver function
595			*/
596
597	cebix	1.4	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt)
598	cebix	1.1	{
599			struct SheepVars v = (struct SheepVars )pt->data;
600	cebix	1.4	struct sk_buff *skb2;
601			int fake;
602			int multicast;
603	cebix	1.1	D(bug("sheep_net: packet received\n"));
604
605	cebix	1.4	multicast = (skb->mac.ethernet->h_dest[0] & ETH_ADDR_MULTICAST);
606			fake = is_fake_addr(v, &skb->mac.ethernet->h_dest);
607
608			/* Packet sent by us? Then discard */
609			if (is_fake_addr(v, &skb->mac.ethernet->h_source) \|\| skb->protocol == PROT_MAGIC)
610			goto drop;
611
612			/* If the packet is not meant for this host, discard it */
613			if (!is_local_addr(v, &skb->mac.ethernet->h_dest) && !multicast && !fake)
614			goto drop;
615
616			/* Discard packets if queue gets too full */
617			if (skb_queue_len(&v->queue) > MAX_QUEUE)
618			goto drop;
619
620			/* Apply any filters here (if fake is true, then we know we want this packet) */
621			if (!fake) {
622			if ((skb->protocol == htons(ETH_P_IP))
623			&& (!v->ipfilter \|\| (ntohl(skb->h.ipiph->daddr) != v->ipfilter && !multicast)))
624			goto drop;
625	cebix	1.1	}
626
627	cebix	1.4	/* Masquerade (we are typically a clone - best to make a real copy) */
628			skb2 = skb_copy(skb, GFP_ATOMIC);
629			if (!skb2)
630			goto drop;
631			kfree_skb(skb);
632			skb = skb2;
633			masquerade(v, skb);
634	cebix	1.1
635	cebix	1.4	/* We also want the Ethernet header */
636	cebix	1.1	skb_push(skb, skb->data - skb->mac.raw);
637
638	cebix	1.4	/* Enqueue packet */
639	cebix	1.1	skb_queue_tail(&v->queue, skb);
640
641	cebix	1.4	/* Unblock blocked read */
642	cebix	1.1	wake_up(&v->wait);
643	cebix	1.4	return 0;
644
645			drop:
646			kfree_skb(skb);
647	cebix	1.1	return 0;
648			}
649	cebix	1.9
650			MODULE_LICENSE("GPL");