bpf.c

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/*
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * This code is derived from the Stanford/CMU enet packet filter,
 * (net/enet.c) distributed in 4.3BSD Unix.
 *
 * SCCSID: @(#)bpf.c	4.1	ULTRIX	1/25/91
 * Based on:
 * rcsid[] = "$Header: bpf.c,v 1.21 91/01/14 21:52:48 mccanne Exp $"
 */

#include "bpfilter.h"

#if (NBPFILTER > 0)

#ifndef __GNUC__
#define inline
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <sys/buf.h>
#include <sys/dir.h>
#include <sys/user.h>
#include <sys/ioctl.h>
#include <sys/map.h>
#include <sys/proc.h>

#include <sys/file.h>
#ifdef sparc
#include <sys/stream.h>
#endif
#include <sys/tty.h>
#include <sys/uio.h>

#include <sys/protosw.h>
#include <sys/socket.h>
#include <net/if.h>

#include <net/bpf.h>
#include <net/bpfdesc.h>

#include <sys/errno.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <sys/kernel.h>

#define PRINET  26			/* interruptible */

/*
 *  'bpf_iftab' is the driver state table per logical unit number
 *  'bpf_dtab' holds the descriptors, indexed by minor device #
 *  'bpf_units' is the number of attached units
 *
 * We really don't need NBPFILTER bpf_if entries, but this eliminates
 * the need to account for all possible drivers here.
 * This problem will go away when these structures are allocated dynamically.
 */
static struct bpf_if 	bpf_iftab[NBPFILTER];
static struct bpf_d	bpf_dtab[NBPFILTER];
static u_int		bpf_units = 0;

static void	bpf_timeout();
static void	bpf_ifname();
static void	catchpacket();
static int	bpf_setif();
static int	bpf_initd();

/*
 * The default filter accepts the maximum number of bytes from each packet.
 */
struct bpf_insn bpf_default_filter[] = {
	BPF_STMT(RetOp, MCLBYTES),
};

/*
 * This routine was inspired by/stolen from ../sys/uipc_socket.c
 * Move data from 'm' to user's read buffer.  
 * We assume 'm' is not chained.
 * Returns error code (or 0 if success).
 */
static inline int
bpf_moveout(m, uio)
	register struct mbuf *m;
	register struct uio *uio;
{
	register int len;
	
	len = m->m_len;
	if (uio->uio_resid < len)
		len = uio->uio_resid;

	if (len > 0)
		return uiomove(mtod(m, caddr_t), len, UIO_READ, uio);

	return 0;
}

static int
bpf_movein(uio, linktype, mp, sockp)
	register struct uio *uio;
	int linktype;
	register struct mbuf **mp;
	register struct sockaddr *sockp;
{
	struct mbuf *m;
	int error;
	int len;
	int hlen;

	/*
	 * Build a sockaddr based on the data link layer type.
	 * We do this at this level because the ethernet header
	 * is copied directly into the data field of the sockaddr.
	 * In the case of SLIP, there is no header and the packet
	 * is forwarded as is.
	 * Also, we are careful to leave room at the front of the mbuf
	 * for the link level header.
	 */
	switch (linktype) {
	case DLT_SLIP:
		sockp->sa_family = AF_INET;
		hlen = 0;
		break;

	case DLT_EN10MB:
		sockp->sa_family = AF_UNSPEC;
		/* XXX Would MAXLINKHDR be better? */
		hlen = sizeof(struct ether_header);
		break;

	default:
		return EIO;
	}

	len = uio->uio_resid;
	if ((unsigned)len > MCLBYTES)
		return EIO;

	MGET(m, M_WAIT, MT_DATA);
	if (m == 0)
		return ENOBUFS;
	if (len > MLEN) {
		MCLGET(m);
		if (m->m_len != MCLBYTES) {
			error = ENOBUFS;
			goto bad;
		}
	}
	m->m_len = len;
	*mp = m;
	/*
	 * Make room for link header.
	 */
	if (hlen) {
		m->m_len -= hlen;
		m->m_off += hlen;

		error = uiomove((caddr_t)sockp->sa_data, hlen, UIO_WRITE, uio);
		if (error)
			goto bad;
	}
	error = uiomove(mtod(m, caddr_t), len - hlen, UIO_WRITE, uio);
	if (!error) 
		return 0;
 bad:
	m_freem(m);
	return error;
}

/*
 * Attach 'd' to the bpf interface 'bp', i.e. make 'd' listen on 'bp'.
 * Must be called at splimp.
 */
static void
bpf_attachd(d, bp)
	struct bpf_d *d;
	struct bpf_if *bp;
{
	/* Point 'd' at 'bp'. */
	d->bd_bif = bp;

	/* Add 'd' to 'bp's list of listeners. */
	d->bd_next = bp->bif_dlist;
	bp->bif_dlist = d;

	/*
	 * Let the driver know we're here (if it doesn't already).
	 */
	*bp->bif_driverp = bp;
}

static void
bpf_detachd(d)
	struct bpf_d *d;
{
	struct bpf_d **p;
	struct bpf_if *bp;

	bp = d->bd_bif;
	/*
	 * Check if this descriptor had requested promiscuous mode.
	 * If so, turn it off.
	 */
	if (d->bd_promisc) {
		d->bd_promisc = 0;
		if (ifpromisc(bp->bif_ifp, 0))
			/*
			 * Something is really wrong if we were able to put
			 * the driver into promiscuous mode, but can't
			 * take it out.
			 */
			panic("bpf_detachd: exit promisc unsucessful");
	}
	/* Remove 'd' from the interface's descriptor list. */
	p = &bp->bif_dlist;
	while (*p != d) {
		p = &(*p)->bd_next;
		if (*p == 0)
			panic("bpf_detachd: descriptor not in list");
	}
	*p = (*p)->bd_next;
	if (bp->bif_dlist == 0)
		/*
		 * Let the driver know that there are no more listeners.
		 */
		*d->bd_bif->bif_driverp = 0;
	d->bd_bif = 0;
}


/*
 * Mark a descriptor free by making it point to itself. 
 * This is probably cheaper than marking with a constant since
 * the address should be in a register anyway.
 */
#define D_ISFREE(d) ((d) == (d)->bd_next)
#define D_MARKFREE(d) ((d)->bd_next = (d))
#define D_MARKUSED(d) ((d)->bd_next = 0)

/*
 *  bpfopen - open ethernet device
 *
 *  Errors:	ENXIO	- illegal minor device number
 *		EBUSY	- too many files open
 */
/* ARGSUSED */
int
bpfopen(dev, flag)
	dev_t dev;
	int flag;
{
	int error, s;
	register struct bpf_d *d;
	
	if (minor(dev) >= NBPFILTER)
		return ENXIO;

	/*
	 * Each minor can be opened by only one process.  If the requested
	 * minor is in use, return EBUSY.
	 */
	s = splimp();
	d = &bpf_dtab[minor(dev)];
	if (!D_ISFREE(d)) {
		splx(s);
		return EBUSY;
	} else
		/* Mark "free" and do most initialization. */
		bzero((char *)d, sizeof(*d));
	d->bd_filter = bpf_default_filter;
	splx(s);

	error = bpf_initd(d);
	if (error) {
		D_MARKFREE(d);
		return error;
	}
	return 0;
}

/*
 * Close the descriptor by detaching it from its interface,
 * deallocating its buffers, and marking it free.
 */
/* ARGSUSED */
void
bpfclose(dev, flag)
	dev_t dev;
	int flag;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	int s;

	s = splimp();
	if (d->bd_bif)
		bpf_detachd(d);
	splx(s);

	/* Let the buffers go. */
	m_freem(d->bd_hbuf);
	m_freem(d->bd_sbuf);
	m_freem(d->bd_fbuf);
	m_freem(d->bd_filterm);
	
	D_MARKFREE(d);
}

#define RS_IDLE 0
#define RS_WAIT 1
#define RS_TIMEDOUT 2

/*
 *  bpfread - read next chunk of packets from buffers
 */
int
bpfread(dev, uio)
	dev_t dev;
	register struct uio *uio;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	struct mbuf *m;
	int error;
	int s;

	/*
	 * Restrict application to use a buffer the same size as 
	 * as kernel buffers.
	 */
	if (uio->uio_resid != MCLBYTES)
		return EIO;

	s = splimp();
	/*
	 * If the hold buffer is empty, then set a timer and sleep
	 * until either the timeout has occurred or enough packets have
	 * arrived to fill the store buffer.
	 */
	while (d->bd_hbuf == 0) {
		if (d->bd_immediate && d->bd_sbuf->m_len) {
			/*
			 * A packet(s) either arrived since the previous
			 * read or arrived while we were asleep.
			 * Rotate the buffers and return what's here.
			 */
			d->bd_hbuf = d->bd_sbuf;
			d->bd_sbuf = d->bd_fbuf;
			d->bd_sbuf->m_len = 0;
			d->bd_fbuf = 0;
			break;
		}
		if (d->bd_rtout) {
			/*
			 * If there was a previous timeout pending for this 
			 * file, cancel it before setting another.  This is
			 * necessary since a cancel after the sleep might 
			 * never happen if the read is interrupted by a signal.
			 */
			if (d->bd_state == RS_WAIT)
				untimeout(bpf_timeout, (caddr_t)d);
			timeout(bpf_timeout, (caddr_t)d, (int)d->bd_rtout);
			d->bd_state = RS_WAIT;
		}
		else
			d->bd_state = RS_IDLE;
		
		sleep((caddr_t)d, PRINET);
		
		if (d->bd_state == RS_WAIT) {
			untimeout(bpf_timeout, (caddr_t)d);
			d->bd_state = RS_IDLE;
		}
		else if (d->bd_state == RS_TIMEDOUT) {
			/*
			 * On a timeout, return what's in the buffer,
			 * which may be nothing.  We do this by moving
			 * the store buffer into the hold slot.
			 */
			if (d->bd_hbuf)
				/*
				 * We filled up the buffer in between 
				 * getting the timeout and arriving
				 * here, so we don't need to rotate.
				 */
				break;

			if (d->bd_sbuf->m_len == 0) {
				splx(s);
				return(0);
			}
			d->bd_hbuf = d->bd_sbuf;
			d->bd_sbuf = d->bd_fbuf;
			d->bd_sbuf->m_len = 0;
			d->bd_fbuf = 0;
			break;
		}
	}
	/*
	 * At this point, we know we have something in the hold slot.
	 */
	m = d->bd_hbuf;

	splx(s);
	
	/*  
	 * Move data from hold buffer into user space.
	 * We know the entire buffer is transferred since
	 * we checked above that the read buffer is MCLBYTES.
	 */
	error = bpf_moveout(m, uio);

	s = splimp();
	if (d->bd_fbuf != 0)
		panic("bpfread: free mbuf slot occupied");
	d->bd_fbuf = m;
	d->bd_hbuf = (struct mbuf *)0;
	splx(s);
	
	return error;
}


/*
 * If there are processes select sleeping on this descriptor,
 * wake them up.  
 */
static inline void
bpf_wakeup(d)
	register struct bpf_d *d;
{
	if (d->bd_SelProc) {
		selwakeup(d->bd_SelProc, d->bd_SelColl);
		d->bd_SelColl = 0;
		d->bd_SelProc = 0;
	}
}

/*
 *  bpf_timeout - process ethernet read timeout
 */
static void
bpf_timeout(d)
	register struct bpf_d * d;
{
	register int s = splimp();

	d->bd_state = RS_TIMEDOUT;
	wakeup((caddr_t)d);
	bpf_wakeup(d);

	splx(s);
}

int
bpfwrite(dev, uio)
	dev_t dev;
	struct uio *uio;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	struct ifnet *ifp;
	struct mbuf *m;
	int error, s;
	static struct sockaddr dst;

	if (d->bd_bif == 0)
		return ENXIO;

	ifp = d->bd_bif->bif_ifp;

	if (uio->uio_resid == 0)
		return 0;
	if (uio->uio_resid > ifp->if_mtu)
		return EMSGSIZE;

	error = bpf_movein(uio, d->bd_bif->bif_devp.bdev_type, &m, &dst);
	if (error)
		return error;

	s = splnet();
	error = (*ifp->if_output)(ifp, m, &dst);
	splx(s);
	/*
	 * The driver frees the mbuf. 
	 */
	return error;
}

/*
 * Reset a descriptor by flushing its packet before
 * and clearing the receive and drop counts.  Should
 * be called at splimp.
 */
static void
reset_d(d)
	struct bpf_d *d;
{
	if (d->bd_hbuf) {
		/* Free the hold buffer. */
		d->bd_fbuf = d->bd_hbuf;
		d->bd_hbuf = 0;
	}
	d->bd_sbuf->m_len = 0;
	d->bd_rcount = 0;
	d->bd_dcount = 0;
}

/*
 *  bpfioctl - packet filter control
 *
 *  FIONREAD		Check for read packet available.
 *  SIOCGIFADDR		Get interface address - convenient hook to driver.
 *  BIOCGFLEN		Get max filter len.
 *  BIOCGBLEN		Get buffer len [for read()].
 *  BIOCSETF		Set ethernet read filter.
 *  BIOCFLUSH		Flush read packet buffer.
 *  BIOCPROMISC		Put interface into promiscuous mode.
 *  BIOCDEVP		Get device parameters.
 *  BIOCGETIF		Get interface name.
 *  BIOCSETIF		Set interface.
 *  BIOCSRTIMEOUT	Set read timeout.
 *  BIOCGRTIMEOUT	Get read timeout.
 *  BIOCGSTATS		Get packet stats.
 *  BIOCIMMEDIATE	Set immediate mode.
 */
/* ARGSUSED */
int
bpfioctl(dev, cmd, addr, flag)
	dev_t dev;
	int cmd;
	caddr_t addr;
	int flag;
{
	register struct bpf_d *d = &bpf_dtab[minor(dev)];
	int s, error = 0;

	switch (cmd) {

	default:
		error = EINVAL;
		break;

	/*
	 * Check for read packet available.
	 */
	case FIONREAD:
		{
			int n;
		
			s = splimp();
			n = d->bd_sbuf->m_len;
			if (d->bd_hbuf) 
				n += d->bd_hbuf->m_len;
			splx(s);

			*(int *)addr = n;
			break;
		}

	case SIOCGIFADDR:
		{
			struct ifnet *ifp;

			if (d->bd_bif == 0)
				error = EINVAL;
			else {
				ifp = d->bd_bif->bif_ifp;
				error =  (*ifp->if_ioctl)(ifp, cmd, addr);
			}
			break;
		}

	/*
	 * Get max filter len.
	 */
	case BIOCGFLEN:
		*(u_int *)addr = MCLBYTES / sizeof(struct bpf_insn);
		break;
	/*
	 * Get buffer len [for read()].
	 */
	case BIOCGBLEN:
		*(u_int *)addr = MCLBYTES;
		break;

	/*
	 * Set ethernet read filter.
	 */
        case BIOCSETF:
		error = bpf_setf(d, (struct bpf_program *)addr);
		break;