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/module.h>
#include <linux/version.h>

#ifdef CONFIG_MODVERSIONS
#define MODVERSIONS
#include <linux/modversions.h>
#endif

#ifdef CONFIG_SMP
#define __SMP__
#endif

#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>

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 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
 */

void cleanup_module(void)
{
        /* Unregister driver */
        misc_deregister(&sheep_net_device);
        D(bug("Sheep net driver removed\n"));
}


/*
 *  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:	1.5
Committed:	2001-03-28T14:18:58Z (23 years, 3 months ago) by cebix
Content type:	text/plain
Branch:	MAIN
CVS Tags:	snapshot-29052001, release-0_9-1
Changes since 1.4:	+15 -6 lines
Log Message:	cleaned up a little
#	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	1.3	* sheep_net (C) 1999-2001 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			#include <linux/module.h>
22			#include <linux/version.h>
23	cebix	1.5
24			#ifdef CONFIG_MODVERSIONS
25			#define MODVERSIONS
26			#include <linux/modversions.h>
27			#endif
28
29			#ifdef CONFIG_SMP
30			#define __SMP__
31			#endif
32
33	cebix	1.1	#include <linux/miscdevice.h>
34			#include <linux/netdevice.h>
35			#include <linux/etherdevice.h>
36			#include <linux/if_ether.h>
37			#include <linux/if_arp.h>
38			#include <linux/fs.h>
39			#include <linux/poll.h>
40			#include <linux/init.h>
41	cebix	1.4	#include <linux/in.h>
42			#include <linux/wait.h>
43	cebix	1.1	#include <net/sock.h>
44	cebix	1.4	#include <net/arp.h>
45			#include <net/ip.h>
46	cebix	1.1	#include <asm/uaccess.h>
47
48	cebix	1.5	MODULE_AUTHOR("Christian Bauer");
49			MODULE_DESCRIPTION("Pseudo ethernet device for emulators");
50
51	cebix	1.4	/* Compatibility glue */
52			#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,4,0)
53			#define LINUX_24
54			#else
55			#define net_device device
56			typedef struct wait_queue *wait_queue_head_t;
57			#define init_waitqueue_head(x) *(x)=NULL
58			#endif
59
60	cebix	1.1	#define DEBUG 0
61
62			#define bug printk
63			#if DEBUG
64			#define D(x) (x);
65			#else
66			#define D(x) ;
67			#endif
68
69
70	cebix	1.4	/* Constants */
71			#define SHEEP_NET_MINOR 198 /* Driver minor number */
72			#define MAX_QUEUE 32 /* Maximum number of packets in queue */
73			#define PROT_MAGIC 1520 /* Our "magic" protocol type */
74	cebix	1.1
75	cebix	1.4	#define ETH_ADDR_MULTICAST 0x1
76
77			#define SIOC_MOL_GET_IPFILTER SIOCDEVPRIVATE
78			#define SIOC_MOL_SET_IPFILTER (SIOCDEVPRIVATE + 1)
79
80			/* Prototypes */
81	cebix	1.1	static int sheep_net_open(struct inode inode, struct file f);
82			static int sheep_net_release(struct inode inode, struct file f);
83			static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off);
84			static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off);
85			static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait);
86			static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg);
87	cebix	1.4	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt);
88	cebix	1.1
89
90			/*
91			* Driver private variables
92			*/
93
94			struct SheepVars {
95	cebix	1.4	struct net_device ether; / The Ethernet device we're attached to */
96			struct sock skt; / Socket for communication with Ethernet card */
97			struct sk_buff_head queue; /* Receiver packet queue */
98			struct packet_type pt; /* Receiver packet type */
99			wait_queue_head_t wait; /* Wait queue for blocking read operations */
100			u32 ipfilter; /* Only receive IP packets destined for this address (host byte order) */
101			char eth_addr[6]; /* Hardware address of the Ethernet card */
102			char fake_addr[6]; /* Local faked hardware address (what SheepShaver sees) */
103	cebix	1.1	};
104
105
106			/*
107			* file_operations structure - has function pointers to the
108			* various entry points for device operations
109			*/
110
111			static struct file_operations sheep_net_fops = {
112	cebix	1.4	read: sheep_net_read,
113			write: sheep_net_write,
114			poll: sheep_net_poll,
115			ioctl: sheep_net_ioctl,
116			open: sheep_net_open,
117			release: sheep_net_release,
118	cebix	1.1	};
119
120
121			/*
122			* miscdevice structure for driver initialization
123			*/
124
125			static struct miscdevice sheep_net_device = {
126	cebix	1.4	SHEEP_NET_MINOR, /* minor number */
127			"sheep_net", /* name */
128	cebix	1.1	&sheep_net_fops,
129			NULL,
130			NULL
131			};
132
133
134			/*
135			* Initialize module
136			*/
137
138			int init_module(void)
139			{
140			int ret;
141
142	cebix	1.4	/* Register driver */
143	cebix	1.1	ret = misc_register(&sheep_net_device);
144			D(bug("Sheep net driver installed\n"));
145			return ret;
146			}
147
148
149			/*
150			* Deinitialize module
151			*/
152
153	cebix	1.5	void cleanup_module(void)
154	cebix	1.1	{
155	cebix	1.4	/* Unregister driver */
156	cebix	1.5	misc_deregister(&sheep_net_device);
157	cebix	1.1	D(bug("Sheep net driver removed\n"));
158			}
159
160
161			/*
162			* Driver open() function
163			*/
164
165			static int sheep_net_open(struct inode inode, struct file f)
166			{
167			struct SheepVars *v;
168			D(bug("sheep_net: open\n"));
169
170	cebix	1.4	/* Must be opened with read permissions */
171	cebix	1.1	if ((f->f_flags & O_ACCMODE) == O_WRONLY)
172			return -EPERM;
173
174	cebix	1.4	/* Allocate private variables */
175	cebix	1.1	v = (struct SheepVars *)f->private_data = kmalloc(sizeof(struct SheepVars), GFP_USER);
176			if (v == NULL)
177			return -ENOMEM;
178			memset(v, 0, sizeof(struct SheepVars));
179			skb_queue_head_init(&v->queue);
180	cebix	1.4	init_waitqueue_head(&v->wait);
181			v->fake_addr[0] = 0xfe;
182			v->fake_addr[1] = 0xfd;
183			v->fake_addr[2] = 0xde;
184			v->fake_addr[3] = 0xad;
185			v->fake_addr[4] = 0xbe;
186			v->fake_addr[5] = 0xef;
187	cebix	1.1
188	cebix	1.4	/* Yes, we're open */
189	cebix	1.1	MOD_INC_USE_COUNT;
190			return 0;
191			}
192
193
194			/*
195			* Driver release() function
196			*/
197
198			static int sheep_net_release(struct inode inode, struct file f)
199			{
200			struct SheepVars v = (struct SheepVars )f->private_data;
201			struct sk_buff *skb;
202			D(bug("sheep_net: close\n"));
203
204	cebix	1.4	/* Detach from Ethernet card */
205	cebix	1.1	if (v->ether) {
206			dev_remove_pack(&v->pt);
207			sk_free(v->skt);
208			v->skt = NULL;
209	cebix	1.4	#ifdef LINUX_24
210			dev_put( v->ether );
211			#endif
212	cebix	1.1	v->ether = NULL;
213			}
214
215	cebix	1.4	/* Empty packet queue */
216	cebix	1.1	while ((skb = skb_dequeue(&v->queue)) != NULL)
217			dev_kfree_skb(skb);
218
219	cebix	1.4	/* Free private variables */
220	cebix	1.1	kfree(v);
221
222	cebix	1.4	/* Sorry, we're closed */
223	cebix	1.1	MOD_DEC_USE_COUNT;
224			return 0;
225			}
226
227
228			/*
229	cebix	1.4	* Check whether an Ethernet address is the local (attached) one or
230			* the fake one
231			*/
232
233			static inline int is_local_addr(struct SheepVars v, void a)
234			{
235			return memcmp(a, v->eth_addr, 6) == 0;
236			}
237
238			static inline int is_fake_addr(struct SheepVars v, void a)
239			{
240			return memcmp(a, v->fake_addr, 6) == 0;
241			}
242
243
244			/*
245			* Outgoing packet. Replace the fake enet addr with the real local one.
246			*/
247
248			static inline void do_demasq(struct SheepVars v, u8 p)
249			{
250			memcpy(p, v->eth_addr, 6);
251			}
252
253			static void demasquerade(struct SheepVars v, struct sk_buff skb)
254			{
255			u8 *p = skb->mac.raw;
256			int proto = (p[12] << 8) \| p[13];
257
258			do_demasq(v, p + 6); /* source address */
259
260			/* Need to fix ARP packets */
261			if (proto == ETH_P_ARP) {
262			if (is_fake_addr(v, p + 14 + 8)) /* sender HW-addr */
263			do_demasq(v, p + 14 + 8);
264			}
265
266			/* ...and AARPs (snap code: 0x00,0x00,0x00,0x80,0xF3) */
267			if (p[17] == 0 && p[18] == 0 && p[19] == 0 && p[20] == 0x80 && p[21] == 0xf3) {
268			/* XXX: we should perhaps look for the 802 frame too */
269			if (is_fake_addr(v, p + 30))
270			do_demasq(v, p + 30); /* sender HW-addr */
271			}
272			}
273
274
275			/*
276			* Incoming packet. Replace the local enet addr with the fake one.
277			*/
278
279			static inline void do_masq(struct SheepVars v, u8 p)
280			{
281			memcpy(p, v->fake_addr, 6);
282			}
283
284			static void masquerade(struct SheepVars v, struct sk_buff skb)
285			{
286			u8 *p = skb->mac.raw;
287			if (!(p[0] & ETH_ADDR_MULTICAST))
288			do_masq(v, p); /* destination address */
289
290			/* XXX: reverse ARP might need to be fixed */
291			}
292
293
294			/*
295	cebix	1.1	* Driver read() function
296			*/
297
298			static ssize_t sheep_net_read(struct file f, char buf, size_t count, loff_t *off)
299			{
300			struct SheepVars v = (struct SheepVars )f->private_data;
301			struct sk_buff *skb;
302	cebix	1.4
303	cebix	1.1	D(bug("sheep_net: read\n"));
304
305			for (;;) {
306
307	cebix	1.4	/* Get next packet from queue */
308	cebix	1.1	skb = skb_dequeue(&v->queue);
309			if (skb != NULL \|\| (f->f_flags & O_NONBLOCK))
310			break;
311
312	cebix	1.4	/* No packet in queue and in blocking mode, so block */
313	cebix	1.1	interruptible_sleep_on(&v->wait);
314
315	cebix	1.4	/* Signal received? Then bail out */
316			if (signal_pending(current))
317			return -EINTR;
318	cebix	1.1	}
319			if (skb == NULL)
320			return -EAGAIN;
321
322	cebix	1.4	/* Pass packet to caller */
323	cebix	1.1	if (count > skb->len)
324			count = skb->len;
325			if (copy_to_user(buf, skb->data, count))
326			count = -EFAULT;
327			dev_kfree_skb(skb);
328			return count;
329			}
330
331
332			/*
333			* Driver write() function
334			*/
335
336			static ssize_t sheep_net_write(struct file f, const char buf, size_t count, loff_t *off)
337			{
338			struct SheepVars v = (struct SheepVars )f->private_data;
339			struct sk_buff *skb;
340			char *p;
341			D(bug("sheep_net: write\n"));
342
343	cebix	1.4	/* Check packet size */
344	cebix	1.1	if (count < sizeof(struct ethhdr))
345			return -EINVAL;
346			if (count > 1514)
347			count = 1514;
348
349	cebix	1.4	/* Interface active? */
350	cebix	1.1	if (v->ether == NULL)
351			return count;
352
353	cebix	1.4	/* Allocate buffer for packet */
354	cebix	1.1	skb = dev_alloc_skb(count);
355			if (skb == NULL)
356			return -ENOBUFS;
357
358	cebix	1.4	/* Stuff packet in buffer */
359	cebix	1.1	p = skb_put(skb, count);
360			if (copy_from_user(p, buf, count)) {
361			kfree_skb(skb);
362			return -EFAULT;
363			}
364
365	cebix	1.4	/* Transmit packet */
366	cebix	1.1	atomic_add(skb->truesize, &v->skt->wmem_alloc);
367			skb->sk = v->skt;
368			skb->dev = v->ether;
369			skb->priority = 0;
370			skb->nh.raw = skb->h.raw = skb->data + v->ether->hard_header_len;
371	cebix	1.4	skb->mac.raw = skb->data;
372
373			/* Base the IP-filtering on the IP address in any outgoing ARP packets */
374			if (skb->mac.ethernet->h_proto == htons(ETH_P_ARP)) {
375			u8 p = &skb->data[14+14]; / source IP address */
376			u32 ip = (p[0] << 24) \| (p[1] << 16) \| (p[2] << 8) \| p[3];
377			if (ip != v->ipfilter) {
378			v->ipfilter = ip;
379			printk("sheep_net: ipfilter set to %d.%d.%d.%d\n", (ip >> 24) & 0xff, (ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
380			}
381			}
382
383			/* Is this packet addressed solely to the local host? */
384			if (is_local_addr(v, skb->data) && !(skb->data[0] & ETH_ADDR_MULTICAST)) {
385			skb->protocol = eth_type_trans(skb, v->ether);
386			netif_rx(skb);
387			return count;
388			}
389			if (skb->data[0] & ETH_ADDR_MULTICAST) {
390			/* We can't clone the skb since we will manipulate the data below */
391			struct sk_buff *lskb = skb_copy(skb, GFP_ATOMIC);
392			if (lskb) {
393			lskb->protocol = eth_type_trans(lskb, v->ether);
394			netif_rx(lskb);
395			}
396			}
397
398			/* Outgoing packet (will be on the net) */
399			demasquerade(v, skb);
400
401			skb->protocol = PROT_MAGIC; /* Magic value (we can recognize the packet in sheep_net_receiver) */
402	cebix	1.1	dev_queue_xmit(skb);
403			return count;
404			}
405
406
407			/*
408			* Driver poll() function
409			*/
410
411			static unsigned int sheep_net_poll(struct file f, struct poll_table_struct wait)
412			{
413			struct SheepVars v = (struct SheepVars )f->private_data;
414			D(bug("sheep_net: poll\n"));
415
416	cebix	1.4	/* Packets in queue? Then return */
417			if (!skb_queue_empty(&v->queue))
418	cebix	1.1	return POLLIN \| POLLRDNORM;
419
420	cebix	1.4	/* Otherwise wait for packet */
421	cebix	1.1	poll_wait(f, &v->wait, wait);
422	cebix	1.4	if (!skb_queue_empty(&v->queue))
423	cebix	1.1	return POLLIN \| POLLRDNORM;
424	cebix	1.4	else
425	cebix	1.1	return 0;
426			}
427
428
429			/*
430			* Driver ioctl() function
431			*/
432
433			static int sheep_net_ioctl(struct inode inode, struct file f, unsigned int code, unsigned long arg)
434			{
435			struct SheepVars v = (struct SheepVars )f->private_data;
436			D(bug("sheep_net: ioctl %04x\n", code));
437
438			switch (code) {
439
440	cebix	1.4	/* Attach to Ethernet card
441			arg: pointer to name of Ethernet device (char[8]) */
442	cebix	1.1	case SIOCSIFLINK: {
443			char name[8];
444	cebix	1.4	int err;
445	cebix	1.1
446	cebix	1.4	/* Already attached? */
447	cebix	1.1	if (v->ether)
448			return -EBUSY;
449
450	cebix	1.4	/* Get Ethernet card name */
451	cebix	1.1	if (copy_from_user(name, (void *)arg, 8))
452			return -EFAULT;
453			name[7] = 0;
454
455	cebix	1.4	/* Find card */
456			#ifdef LINUX_24
457			v->ether = dev_get_by_name(name);
458			#else
459	cebix	1.1	dev_lock_list();
460			v->ether = dev_get(name);
461	cebix	1.4	#endif
462	cebix	1.1	if (v->ether == NULL) {
463	cebix	1.4	err = -ENODEV;
464			goto error;
465	cebix	1.1	}
466
467	cebix	1.4	/* Is it Ethernet? */
468	cebix	1.1	if (v->ether->type != ARPHRD_ETHER) {
469	cebix	1.4	err = -EINVAL;
470			goto error;
471	cebix	1.1	}
472
473	cebix	1.4	/* Remember the card's hardware address */
474			memcpy(v->eth_addr, v->ether->dev_addr, 6);
475
476			/* Allocate socket */
477	cebix	1.1	v->skt = sk_alloc(0, GFP_USER, 1);
478			if (v->skt == NULL) {
479	cebix	1.4	err = -ENOMEM;
480			goto error;
481	cebix	1.1	}
482			v->skt->dead = 1;
483
484	cebix	1.4	/* Attach packet handler */
485	cebix	1.1	v->pt.type = htons(ETH_P_ALL);
486			v->pt.dev = v->ether;
487			v->pt.func = sheep_net_receiver;
488			v->pt.data = v;
489			dev_add_pack(&v->pt);
490	cebix	1.4	#ifndef LINUX_24
491	cebix	1.1	dev_unlock_list();
492	cebix	1.4	#endif
493	cebix	1.1	return 0;
494	cebix	1.4
495			error:
496			#ifdef LINUX_24
497			if (v->ether)
498			dev_put(v->ether);
499			#else
500			dev_unlock_list();
501			#endif
502			v->ether = NULL;
503			return err;
504	cebix	1.1	}
505
506	cebix	1.4	/* Get hardware address of the sheep_net module
507			arg: pointer to buffer (6 bytes) to store address */
508	cebix	1.1	case SIOCGIFADDR:
509	cebix	1.4	if (copy_to_user((void *)arg, v->fake_addr, 6))
510			return -EFAULT;
511			return 0;
512
513			/* Set the hardware address of the sheep_net module
514			arg: pointer to new address (6 bytes) */
515			case SIOCSIFADDR:
516			if (copy_from_user(v->fake_addr, (void*)arg, 6))
517	cebix	1.1	return -EFAULT;
518			return 0;
519
520	cebix	1.4	/* Add multicast address
521			arg: pointer to address (6 bytes) */
522	cebix	1.1	case SIOCADDMULTI: {
523			char addr[6];
524			if (v->ether == NULL)
525			return -ENODEV;
526			if (copy_from_user(addr, (void *)arg, 6))
527			return -EFAULT;
528			return dev_mc_add(v->ether, addr, 6, 0);
529			}
530
531	cebix	1.4	/* Remove multicast address
532			arg: pointer to address (6 bytes) */
533	cebix	1.1	case SIOCDELMULTI: {
534			char addr[6];
535			if (v->ether == NULL)
536			return -ENODEV;
537			if (copy_from_user(addr, (void *)arg, 6))
538			return -EFAULT;
539			return dev_mc_delete(v->ether, addr, 6, 0);
540			}
541
542	cebix	1.4	/* Return size of first packet in queue */
543	cebix	1.1	case FIONREAD: {
544			int count = 0;
545			struct sk_buff *skb;
546	cebix	1.4	#ifdef LINUX_24
547			long flags;
548			spin_lock_irqsave(&v->queue.lock, flags);
549			#else
550			cli();
551			#endif
552	cebix	1.1	skb = skb_peek(&v->queue);
553			if (skb)
554			count = skb->len;
555	cebix	1.4	#ifdef LINUX_24
556			spin_unlock_irqrestore(&v->queue.lock, flags);
557			#else
558			sti();
559			#endif
560	cebix	1.1	return put_user(count, (int *)arg);
561			}
562
563	cebix	1.4	case SIOC_MOL_GET_IPFILTER:
564			return put_user(v->ipfilter, (int *)arg);
565
566			case SIOC_MOL_SET_IPFILTER:
567			v->ipfilter = arg;
568			return 0;
569
570	cebix	1.1	default:
571			return -ENOIOCTLCMD;
572			}
573			}
574
575
576			/*
577			* Packet receiver function
578			*/
579
580	cebix	1.4	static int sheep_net_receiver(struct sk_buff skb, struct net_device dev, struct packet_type *pt)
581	cebix	1.1	{
582			struct SheepVars v = (struct SheepVars )pt->data;
583	cebix	1.4	struct sk_buff *skb2;
584			int fake;
585			int multicast;
586	cebix	1.1	D(bug("sheep_net: packet received\n"));
587
588	cebix	1.4	multicast = (skb->mac.ethernet->h_dest[0] & ETH_ADDR_MULTICAST);
589			fake = is_fake_addr(v, &skb->mac.ethernet->h_dest);
590
591			/* Packet sent by us? Then discard */
592			if (is_fake_addr(v, &skb->mac.ethernet->h_source) \|\| skb->protocol == PROT_MAGIC)
593			goto drop;
594
595			/* If the packet is not meant for this host, discard it */
596			if (!is_local_addr(v, &skb->mac.ethernet->h_dest) && !multicast && !fake)
597			goto drop;
598
599			/* Discard packets if queue gets too full */
600			if (skb_queue_len(&v->queue) > MAX_QUEUE)
601			goto drop;
602
603			/* Apply any filters here (if fake is true, then we know we want this packet) */
604			if (!fake) {
605			if ((skb->protocol == htons(ETH_P_IP))
606			&& (!v->ipfilter \|\| (ntohl(skb->h.ipiph->daddr) != v->ipfilter && !multicast)))
607			goto drop;
608	cebix	1.1	}
609
610	cebix	1.4	/* Masquerade (we are typically a clone - best to make a real copy) */
611			skb2 = skb_copy(skb, GFP_ATOMIC);
612			if (!skb2)
613			goto drop;
614			kfree_skb(skb);
615			skb = skb2;
616			masquerade(v, skb);
617	cebix	1.1
618	cebix	1.4	/* We also want the Ethernet header */
619	cebix	1.1	skb_push(skb, skb->data - skb->mac.raw);
620
621	cebix	1.4	/* Enqueue packet */
622	cebix	1.1	skb_queue_tail(&v->queue, skb);
623
624	cebix	1.4	/* Unblock blocked read */
625	cebix	1.1	wake_up(&v->wait);
626	cebix	1.4	return 0;
627
628			drop:
629			kfree_skb(skb);
630	cebix	1.1	return 0;
631			}