ng_device.c

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2002 Mark Santcroos <[email protected]>
 * Copyright (c) 2004-2005 Gleb Smirnoff <[email protected]>
 * Copyright (c) 2025 Quentin Thébault <[email protected]>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Netgraph "device" node
 *
 * This node presents a /dev/ngd%d device that interfaces to an other
 * netgraph node.
 *
 */

#if 0
#define	DBG do { printf("ng_device: %s\n", __func__); } while (0)
#else
#define	DBG do {} while (0)
#endif

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/conf.h>
#include <sys/epoch.h>
#include <sys/fcntl.h>
#include <sys/filio.h>
#include <sys/ioccom.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/poll.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/selinfo.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/uio.h>

#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_var.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>

#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_device.h>
#include <netgraph/ng_parse.h>

#define	ERROUT(x) do { error = (x); goto done; } while (0)

/* Netgraph methods */
static int		ng_device_mod_event(module_t, int, void *);
static ng_constructor_t	ng_device_constructor;
static ng_rcvmsg_t	ng_device_rcvmsg;
static ng_shutdown_t	ng_device_shutdown;
static ng_newhook_t	ng_device_newhook;
static ng_rcvdata_t	ng_device_rcvdata;
static ng_disconnect_t	ng_device_disconnect;

/* List of commands and how to convert arguments to/from ASCII. */
static const struct ng_cmdlist ng_device_cmds[] = {
	{
	  NGM_DEVICE_COOKIE,
	  NGM_DEVICE_GET_DEVNAME,
	  "getdevname",
	  NULL,
	  &ng_parse_string_type
	},
	{
	  NGM_DEVICE_COOKIE,
	  NGM_DEVICE_ETHERALIGN,
	  "etheralign",
	  NULL,
	  NULL
	},
	{ 0 }
};

/* Netgraph type */
static struct ng_type ngd_typestruct = {
	.version =	NG_ABI_VERSION,
	.name =		NG_DEVICE_NODE_TYPE,
	.mod_event =	ng_device_mod_event,
	.constructor =	ng_device_constructor,
	.rcvmsg	=	ng_device_rcvmsg,
	.shutdown = 	ng_device_shutdown,
	.newhook =	ng_device_newhook,
	.rcvdata =	ng_device_rcvdata,
	.disconnect =	ng_device_disconnect,
	.cmdlist =	ng_device_cmds,
};
NETGRAPH_INIT(device, &ngd_typestruct);

/* per node data */
struct ngd_private {
	struct	ifqueue	readq;
	struct	ng_node	*node;
	struct	ng_hook	*hook;
	struct	cdev	*ngddev;
	struct  selinfo rsel;
	struct  selinfo wsel;
	struct	mtx	ngd_mtx;
	int 		unit;
	int		ether_align;
	uint16_t	flags;
#define	NGDF_OPEN	0x0001
#define	NGDF_RWAIT	0x0002
#define	NGDF_DYING	0x0004
};
typedef struct ngd_private *priv_p;

/* unit number allocator entity */
static struct unrhdr *ngd_unit;

/* Maximum number of NGD devices */
#define MAX_NGD	999

static d_close_t ngdclose;
static d_open_t ngdopen;
static d_read_t ngdread;
static d_write_t ngdwrite;
static d_ioctl_t ngdioctl;
static d_poll_t ngdpoll;
static d_kqfilter_t ngdkqfilter;

static int      ngd_kqread_event(struct knote *, long);
static int      ngd_kqwrite_event(struct knote *, long);
static void     ngd_kqread_detach(struct knote *);
static void     ngd_kqwrite_detach(struct knote *);

static const struct filterops ngd_read_filterops = {
	.f_isfd =   1,
	.f_detach = ngd_kqread_detach,
	.f_event =  ngd_kqread_event
};

static const struct filterops ngd_write_filterops = {
	.f_isfd =   1,
	.f_detach = ngd_kqwrite_detach,
	.f_event =  ngd_kqwrite_event
};

static struct cdevsw ngd_cdevsw = {
	.d_version =	D_VERSION,
	.d_open =	ngdopen,
	.d_close =	ngdclose,
	.d_read =	ngdread,
	.d_write =	ngdwrite,
	.d_ioctl =	ngdioctl,
	.d_kqfilter =   ngdkqfilter,
	.d_poll =	ngdpoll,
	.d_name =	NG_DEVICE_DEVNAME,
};

/*
 *****************************************************************************
 *  Netgraph methods
 *****************************************************************************
 */

/*
 * Handle loading and unloading for this node type.
 */
static int
ng_device_mod_event(module_t mod, int event, void *data)
{
	int error = 0;

	switch (event) {
	case MOD_LOAD:
		ngd_unit = new_unrhdr(0, MAX_NGD, NULL);
		break;
	case MOD_UNLOAD:
		delete_unrhdr(ngd_unit);
		break;
	default:
		error = EOPNOTSUPP;
		break;
	}
	return (error);
}

/*
 * create new node
 */
static int
ng_device_constructor(node_p node)
{
	priv_p	priv;

	DBG;

	priv = malloc(sizeof(*priv), M_NETGRAPH, M_WAITOK | M_ZERO);

	/* Allocate unit number */
	priv->unit = alloc_unr(ngd_unit);

	/* Initialize mutexes and queue */
	mtx_init(&priv->ngd_mtx, "ng_device", NULL, MTX_DEF);
	mtx_init(&priv->readq.ifq_mtx, "ng_device queue", NULL, MTX_DEF);
	IFQ_SET_MAXLEN(&priv->readq, ifqmaxlen);

	knlist_init_mtx(&priv->rsel.si_note, &priv->ngd_mtx);
	knlist_init_mtx(&priv->wsel.si_note, &priv->ngd_mtx);

	/* Link everything together */
	NG_NODE_SET_PRIVATE(node, priv);
	priv->node = node;

	priv->ngddev = make_dev(&ngd_cdevsw, priv->unit, UID_ROOT,
	    GID_WHEEL, 0600, NG_DEVICE_DEVNAME "%d", priv->unit);
	if (priv->ngddev == NULL) {
		printf("%s(): make_dev() failed\n", __func__);
		knlist_destroy(&priv->rsel.si_note);
		knlist_destroy(&priv->wsel.si_note);
		mtx_destroy(&priv->ngd_mtx);
		mtx_destroy(&priv->readq.ifq_mtx);
		free_unr(ngd_unit, priv->unit);
		free(priv, M_NETGRAPH);
		return (EINVAL);
	}
	/* XXX: race here? */
	priv->ngddev->si_drv1 = priv;

	/* Give this node the same name as the device (if possible). */
	if (ng_name_node(node, devtoname(priv->ngddev)) != 0)
		log(LOG_WARNING, "%s: can't acquire netgraph name\n",
		    devtoname(priv->ngddev));

	return (0);
}

/*
 * Process control message.
 */

static int
ng_device_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
	const priv_p priv = NG_NODE_PRIVATE(node);
	struct ng_mesg *msg;
	struct ng_mesg *resp = NULL;
	const char *dn;
	int error = 0;

	NGI_GET_MSG(item, msg);

	if (msg->header.typecookie == NGM_DEVICE_COOKIE) {
		switch (msg->header.cmd) {
		case NGM_DEVICE_GET_DEVNAME:
			/* XXX: Fix when MAX_NGD us bigger */
			NG_MKRESPONSE(resp, msg,
			    strlen(NG_DEVICE_DEVNAME) + 4, M_NOWAIT);

			if (resp == NULL)
				ERROUT(ENOMEM);

			dn = devtoname(priv->ngddev);
			strlcpy((char *)resp->data, dn, strlen(dn) + 1);
			break;

		case NGM_DEVICE_ETHERALIGN:
			/* Use ETHER_ALIGN on arches that require it. */
#ifndef __NO_STRICT_ALIGNMENT
			priv->ether_align = ETHER_ALIGN;
#endif
			break;

		default:
			error = EINVAL;
			break;
		}
	} else
		error = EINVAL;

done:
	NG_RESPOND_MSG(error, node, item, resp);
	NG_FREE_MSG(msg);
	return (error);
}

/*
 * Accept incoming hook. We support only one hook per node.
 */
static int
ng_device_newhook(node_p node, hook_p hook, const char *name)
{
	priv_p priv = NG_NODE_PRIVATE(node);

	DBG;

	/* We have only one hook per node */
	if (priv->hook != NULL)
		return (EISCONN);

	priv->hook = hook;

	return (0);
}

/*
 * Receive data from hook, write it to device.
 */
static int
ng_device_rcvdata(hook_p hook, item_p item)
{
	priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
	struct mbuf *m;

	DBG;

	NGI_GET_M(item, m);
	NG_FREE_ITEM(item);

	IF_LOCK(&priv->readq);
	if (_IF_QFULL(&priv->readq)) {
		IF_UNLOCK(&priv->readq);
		NG_FREE_M(m);
		return (ENOBUFS);
	}

	_IF_ENQUEUE(&priv->readq, m);
	IF_UNLOCK(&priv->readq);
	mtx_lock(&priv->ngd_mtx);
	if (priv->flags & NGDF_RWAIT) {
		priv->flags &= ~NGDF_RWAIT;
		wakeup(priv);
	}
	selwakeup(&priv->rsel);
	KNOTE_LOCKED(&priv->rsel.si_note, 0);
	mtx_unlock(&priv->ngd_mtx);

	return (0);
}

/*
 * Removal of the hook destroys the node.
 */
static int
ng_device_disconnect(hook_p hook)
{
	priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));

	DBG;

	mtx_lock(&priv->ngd_mtx);
	priv->flags |= NGDF_DYING;
	wakeup(priv);
	mtx_unlock(&priv->ngd_mtx);

	destroy_dev(priv->ngddev);

	knlist_clear(&priv->rsel.si_note, 0);
	knlist_clear(&priv->wsel.si_note, 0);
	knlist_destroy(&priv->rsel.si_note);
	knlist_destroy(&priv->wsel.si_note);
	mtx_destroy(&priv->ngd_mtx);

	seldrain(&priv->rsel);
	seldrain(&priv->wsel);

	IF_DRAIN(&priv->readq);
	mtx_destroy(&(priv)->readq.ifq_mtx);

	free_unr(ngd_unit, priv->unit);

	free(priv, M_NETGRAPH);

	ng_rmnode_self(NG_HOOK_NODE(hook));

	return (0);
}

/*
 * Node shutdown. Everything is already done in disconnect method.
 */
static int
ng_device_shutdown(node_p node)
{
	NG_NODE_UNREF(node);
	return (0);
}

/*
 *****************************************************************************
 *  Device methods
 *****************************************************************************
 */

/*
 * the device is opened
 */
static int
ngdopen(struct cdev *dev, int flag, int mode, struct thread *td)
{
	priv_p	priv = (priv_p)dev->si_drv1;

	DBG;

	mtx_lock(&priv->ngd_mtx);
	priv->flags |= NGDF_OPEN;
	mtx_unlock(&priv->ngd_mtx);

	return (0);
}

/*
 * the device is closed
 */
static int
ngdclose(struct cdev *dev, int flag, int mode, struct thread *td)
{
	priv_p	priv = (priv_p)dev->si_drv1;

	DBG;
	mtx_lock(&priv->ngd_mtx);
	priv->flags &= ~NGDF_OPEN;
	mtx_unlock(&priv->ngd_mtx);

	return (0);
}

/*
 * Process IOCTLs
 *
 * At this stage we only return success on FIONBIO to allow setting the device
 * as non-blocking.
 *
 */
static int
ngdioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag,
    struct thread *td)
{
    int error;

    switch (cmd) {
    case FIONBIO:
        error = 0;
        break;
    case FIOASYNC:
        if (*(int *)data != 0)
            error = EINVAL;
        else
            error = 0;
        break;
    default:
        error = ENOTTY;
    }

    return (error);
}

#if 0	/*
	 * The ioctl is transformed into netgraph control message.
	 * We do not process them, yet.
	 */
/*
 * process ioctl
 *
 * they are translated into netgraph messages and passed on
 *
 */
static int
ngdioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag,
    struct thread *td)
{
	struct ngd_softc *sc = &ngd_softc;
	struct ngd_connection *connection = NULL;
	struct ngd_connection *tmp;
	int error = 0;
	struct ng_mesg *msg;
	struct ngd_param_s *datap;

	DBG;

	NG_MKMESSAGE(msg, NGM_DEVICE_COOKIE, cmd, sizeof(struct ngd_param_s),
			M_NOWAIT);
	if (msg == NULL) {
		printf("%s(): msg == NULL\n", __func__);
		goto nomsg;
	}

	/* pass the ioctl data into the ->data area */
	datap = (struct ngd_param_s *)msg->data;
	datap->p = addr;

	NG_SEND_MSG_HOOK(error, sc->node, msg, connection->active_hook, 0);
	if (error)
		printf("%s(): NG_SEND_MSG_HOOK error: %d\n", __func__, error);

nomsg:

	return (0);
}
#endif /* if 0 */

/*
 * This function is called when a read(2) is done to our device.
 * We process one mbuf from queue.
 */
static int
ngdread(struct cdev *dev, struct uio *uio, int flag)
{
	priv_p	priv = (priv_p)dev->si_drv1;
	struct mbuf *m;
	int len, error = 0;

	DBG;

	/* get an mbuf */
	do {
		IF_DEQUEUE(&priv->readq, m);
		if (m == NULL) {
			if (flag & O_NONBLOCK)
				return (EWOULDBLOCK);
			mtx_lock(&priv->ngd_mtx);
			priv->flags |= NGDF_RWAIT;
			if (priv->flags & NGDF_DYING) {
				mtx_unlock(&priv->ngd_mtx);
				error = ENXIO;
			} else
				error = mtx_sleep(priv, &priv->ngd_mtx,
				    PDROP | PCATCH, "ngdread", 0);
			if (error != 0)
				return (error);
		}
	} while (m == NULL);

	while (m && uio->uio_resid > 0 && error == 0) {
		len = MIN(uio->uio_resid, m->m_len);
		if (len != 0)
			error = uiomove(mtod(m, void *), len, uio);
		m = m_free(m);
	}

	if (m)
		m_freem(m);

	return (error);
}

/*
 * This function is called when our device is written to.
 * We read the data from userland into mbuf chain and pass it to the remote
 * hook.
 */
static int
ngdwrite(struct cdev *dev, struct uio *uio, int flag)
{
	struct epoch_tracker et;
	priv_p	priv = (priv_p)dev->si_drv1;
	struct mbuf *m;
	int error = 0;

	DBG;

	if (uio->uio_resid == 0)
		return (0);

	if (uio->uio_resid < 0 || uio->uio_resid > IP_MAXPACKET)
		return (EIO);

	m = m_uiotombuf(uio, M_NOWAIT, 0, priv->ether_align, M_PKTHDR);
	if (m == NULL)
		return (ENOBUFS);

	/* Setting VNET is required if connecting to a ng_bridge. */
	CURVNET_SET(priv->node->nd_vnet);
	NET_EPOCH_ENTER(et);
	NG_SEND_DATA_ONLY(error, priv->hook, m);
	NET_EPOCH_EXIT(et);
	CURVNET_RESTORE();

	return (error);
}

/*
 * we are being polled/selected
 * check if there is data available for read
 */
static int
ngdpoll(struct cdev *dev, int events, struct thread *td)
{
	priv_p	priv = (priv_p)dev->si_drv1;
	int revents = 0;

	if (events & (POLLIN | POLLRDNORM) &&
	    !IFQ_IS_EMPTY(&priv->readq))
		revents |= events & (POLLIN | POLLRDNORM);

	return (revents);
}

static void
ngd_kqread_detach(struct knote *kn)
{
	priv_p  priv = (priv_p)kn->kn_hook;

	knlist_remove(&priv->rsel.si_note, kn, 0);
}

static int
ngd_kqread_event(struct knote *kn, long hint)
{
	priv_p priv = (priv_p)kn->kn_hook;
	struct mbuf *m;

	IFQ_LOCK(&priv->readq);
	if (IFQ_IS_EMPTY(&priv->readq)) {
		kn->kn_data = 0;
	} else {
		/*
		 * Since the queue does not store the total number of bytes that
		 * could be read across all packets and we do not want to
		 * traverse the whole queue, we only report the number of bytes
		 * for the first packet in the queue.
		 */
		IF_POLL(&priv->readq, m);
		kn->kn_data = m->m_len;
	}
	IFQ_UNLOCK(&priv->readq);

	return (kn->kn_data > 0);
}

static void
ngd_kqwrite_detach(struct knote *kn)
{
	priv_p  priv = (priv_p)kn->kn_hook;

	knlist_remove(&priv->wsel.si_note, kn, 0);
}

static int
ngd_kqwrite_event(struct knote *kn, long hint)
{
	kn->kn_data = IP_MAXPACKET;

	return (1);
}

static int
ngdkqfilter(struct cdev *dev, struct knote *kn)
{
	priv_p priv = (priv_p)dev->si_drv1;

	switch (kn->kn_filter) {
	case EVFILT_READ:
		kn->kn_fop = &ngd_read_filterops;
		kn->kn_hook = priv;
		knlist_add(&priv->rsel.si_note, kn, 0);
		return (0);
	case EVFILT_WRITE:
		kn->kn_fop = &ngd_write_filterops;
		kn->kn_hook = priv;
		knlist_add(&priv->wsel.si_note, kn, 0);
		return (0);
	default:
		return (EINVAL);
	}
}