kernel - Fix races created by a comedy of circumstansces (3)

[dragonfly.git] / sys / netgraph7 / ng_gif.c

/*
 * ng_gif.c
 */

/*-
 * Copyright 2001 The Aerospace Corporation.  All rights reserved.
 *
 * 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.
 * 3. The name of The Aerospace Corporation may not be used to endorse or
 *    promote products derived from this software.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AEROSPACE CORPORATION ``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 AEROSPACE CORPORATION 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.
 *
 *
 * Copyright (c) 1996-2000 Whistle Communications, Inc.
 * All rights reserved.
 * 
 * Subject to the following obligations and disclaimer of warranty, use and
 * redistribution of this software, in source or object code forms, with or
 * without modifications are expressly permitted by Whistle Communications;
 * provided, however, that:
 * 1. Any and all reproductions of the source or object code must include the
 *    copyright notice above and the following disclaimer of warranties; and
 * 2. No rights are granted, in any manner or form, to use Whistle
 *    Communications, Inc. trademarks, including the mark "WHISTLE
 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
 *    such appears in the above copyright notice or in the software.
 * 
 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * $FreeBSD: src/sys/netgraph/ng_gif.c,v 1.19 2005/06/10 16:49:21 brooks Exp $
 */

/*
 * ng_gif(4) netgraph node type
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/socket.h>

#include <net/if.h>
#include <net/route.h>
#include <net/if_types.h>
#include <net/if_var.h>
#include <net/if_gif.h>

#include "ng_message.h"
#include "netgraph.h"
#include "ng_parse.h"
#include "ng_gif.h"

#define IFP2NG(ifp)  ((struct ng_node *)((struct gif_softc *)(ifp->if_softc))->gif_netgraph)
#define IFP2NG_SET(ifp, val)  (((struct gif_softc *)(ifp->if_softc))->gif_netgraph = (val))

/* Per-node private data */
struct private {
        struct ifnet    *ifp;           /* associated interface */
        hook_p          lower;          /* lower OR orphan hook connection */
        u_char          lowerOrphan;    /* whether lower is lower or orphan */
};
typedef struct private *priv_p;

/* Functional hooks called from if_gif.c */
static void     ng_gif_input(struct ifnet *ifp, struct mbuf **mp, int af);
static void     ng_gif_input_orphan(struct ifnet *ifp, struct mbuf *m, int af);
static void     ng_gif_attach(struct ifnet *ifp);
static void     ng_gif_detach(struct ifnet *ifp); 

/* Other functions */
static void     ng_gif_input2(node_p node, struct mbuf **mp, int af);
static int      ng_gif_glue_af(struct mbuf **mp, int af);
static int      ng_gif_rcv_lower(node_p node, struct mbuf *m);

/* Netgraph node methods */
static ng_constructor_t ng_gif_constructor;
static ng_rcvmsg_t      ng_gif_rcvmsg;
static ng_shutdown_t    ng_gif_shutdown;
static ng_newhook_t     ng_gif_newhook;
static ng_connect_t     ng_gif_connect;
static ng_rcvdata_t     ng_gif_rcvdata;
static ng_disconnect_t  ng_gif_disconnect;
static int              ng_gif_mod_event(module_t mod, int event, void *data);

/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_gif_cmdlist[] = {
        {
          NGM_GIF_COOKIE,
          NGM_GIF_GET_IFNAME,
          "getifname",
          NULL,
          &ng_parse_string_type
        },
        {
          NGM_GIF_COOKIE,
          NGM_GIF_GET_IFINDEX,
          "getifindex",
          NULL,
          &ng_parse_int32_type
        },
        { 0 }
};

static struct ng_type ng_gif_typestruct = {
        .version =      NG_ABI_VERSION,
        .name =         NG_GIF_NODE_TYPE,
        .mod_event =    ng_gif_mod_event,
        .constructor =  ng_gif_constructor,
        .rcvmsg =       ng_gif_rcvmsg,
        .shutdown =     ng_gif_shutdown,
        .newhook =      ng_gif_newhook,
        .connect =      ng_gif_connect,
        .rcvdata =      ng_gif_rcvdata,
        .disconnect =   ng_gif_disconnect,
        .cmdlist =      ng_gif_cmdlist,
};
MODULE_DEPEND(ng_gif, if_gif, 1,1,1);
NETGRAPH_INIT(gif, &ng_gif_typestruct);

/******************************************************************
                       GIF FUNCTION HOOKS
******************************************************************/

/*
 * Handle a packet that has come in on an interface. We get to
 * look at it here before any upper layer protocols do.
 *
 * NOTE: this function will get called at splimp()
 */
static void
ng_gif_input(struct ifnet *ifp, struct mbuf **mp, int af)
{
        const node_p node = IFP2NG(ifp);
        const priv_p priv = NG_NODE_PRIVATE(node);

        /* If "lower" hook not connected, let packet continue */
        if (priv->lower == NULL || priv->lowerOrphan)
                return;
        ng_gif_input2(node, mp, af);
}

/*
 * Handle a packet that has come in on an interface, and which
 * does not match any of our known protocols (an ``orphan'').
 *
 * NOTE: this function will get called at splimp()
 */
static void
ng_gif_input_orphan(struct ifnet *ifp, struct mbuf *m, int af)
{
        const node_p node = IFP2NG(ifp);
        const priv_p priv = NG_NODE_PRIVATE(node);

        /* If "orphan" hook not connected, let packet continue */
        if (priv->lower == NULL || !priv->lowerOrphan) {
                m_freem(m);
                return;
        }
        ng_gif_input2(node, &m, af);
        if (m != NULL)
                m_freem(m);
}

/*
 * Handle a packet that has come in on a gif interface.
 * Attach the address family to the mbuf for later use.
 *
 * NOTE: this function will get called at splimp()
 */
static void
ng_gif_input2(node_p node, struct mbuf **mp, int af)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        int error;

        /* Glue address family on */
        if ((error = ng_gif_glue_af(mp, af)) != 0)
                return;

        /* Send out lower/orphan hook */
        NG_SEND_DATA_ONLY(error, priv->lower, *mp);
        *mp = NULL;
}

/*
 * A new gif interface has been attached.
 * Create a new node for it, etc.
 */
static void
ng_gif_attach(struct ifnet *ifp)
{
        priv_p priv;
        node_p node;

        /* Create node */
        KASSERT(!IFP2NG(ifp), ("%s: node already exists?", __func__));
        if (ng_make_node_common(&ng_gif_typestruct, &node) != 0) {
                log(LOG_ERR, "%s: can't %s for %s\n",
                    __func__, "create node", ifp->if_xname);
                return;
        }

        /* Allocate private data */
        priv = kmalloc(sizeof(*priv), M_NETGRAPH,
                       M_WAITOK | M_NULLOK | M_ZERO);
        if (priv == NULL) {
                log(LOG_ERR, "%s: can't %s for %s\n",
                    __func__, "allocate memory", ifp->if_xname);
                NG_NODE_UNREF(node);
                return;
        }
        NG_NODE_SET_PRIVATE(node, priv);
        priv->ifp = ifp;
        IFP2NG_SET(ifp, node);

        /* Try to give the node the same name as the interface */
        if (ng_name_node(node, ifp->if_xname) != 0) {
                log(LOG_WARNING, "%s: can't name node %s\n",
                    __func__, ifp->if_xname);
        }
}

/*
 * An interface is being detached.
 * REALLY Destroy its node.
 */
static void
ng_gif_detach(struct ifnet *ifp)
{
        const node_p node = IFP2NG(ifp);
        priv_p priv;

        if (node == NULL)               /* no node (why not?), ignore */
                return;
        priv = NG_NODE_PRIVATE(node);
        NG_NODE_REALLY_DIE(node);       /* Force real removal of node */
        /*
         * We can't assume the ifnet is still around when we run shutdown
         * So zap it now. XXX We HOPE that anything running at this time
         * handles it (as it should in the non netgraph case).
         */
        IFP2NG_SET(ifp, NULL);
        priv->ifp = NULL;       /* XXX race if interrupted an output packet */
        ng_rmnode_self(node);           /* remove all netgraph parts */
}

/*
 * Optimization for gluing the address family onto
 * the front of an incoming packet.
 */
static int
ng_gif_glue_af(struct mbuf **mp, int af)
{
        struct mbuf *m = *mp;
        int error = 0;
        sa_family_t tmp_af;

        tmp_af = (sa_family_t) af;

        /*
         * XXX: should try to bring back some of the optimizations from
         * ng_ether.c
         */

        /*
         * Doing anything more is likely to get more
         * expensive than it's worth..
         * it's probable that everything else is in one
         * big lump. The next node will do an m_pullup()
         * for exactly the amount of data it needs and
         * hopefully everything after that will not
         * need one. So let's just use M_PREPEND.
         */
        M_PREPEND(m, sizeof (tmp_af), M_NOWAIT);
        if (m == NULL) {
                error = ENOBUFS;
                goto done;
        }

#if 0
copy:
#endif
        /* Copy header and return (possibly new) mbuf */
        *mtod(m, sa_family_t *) = tmp_af;
#if 0
        bcopy((caddr_t)&tmp_af, mtod(m, sa_family_t *), sizeof(tmp_af));
#endif
done:
        *mp = m;
        return error;
}

/******************************************************************
                    NETGRAPH NODE METHODS
******************************************************************/

/*
 * It is not possible or allowable to create a node of this type.
 * Nodes get created when the interface is attached (or, when
 * this node type's KLD is loaded).
 */
static int
ng_gif_constructor(node_p node)
{
        return (EINVAL);
}

/*
 * Check for attaching a new hook.
 */
static  int
ng_gif_newhook(node_p node, hook_p hook, const char *name)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        u_char orphan = priv->lowerOrphan;
        hook_p *hookptr;

        /* Divert hook is an alias for lower */
        if (strcmp(name, NG_GIF_HOOK_DIVERT) == 0)
                name = NG_GIF_HOOK_LOWER;

        /* Which hook? */
        if (strcmp(name, NG_GIF_HOOK_LOWER) == 0) {
                hookptr = &priv->lower;
                orphan = 0;
        } else if (strcmp(name, NG_GIF_HOOK_ORPHAN) == 0) {
                hookptr = &priv->lower;
                orphan = 1;
        } else
                return (EINVAL);

        /* Check if already connected (shouldn't be, but doesn't hurt) */
        if (*hookptr != NULL)
                return (EISCONN);

        /* OK */
        *hookptr = hook;
        priv->lowerOrphan = orphan;
        return (0);
}

/*
 * Hooks are attached, adjust to force queueing.
 * We don't really care which hook it is.
 * they should all be queuing for outgoing data.
 */
static  int
ng_gif_connect(hook_p hook)
{
        NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
        return (0);
}

/*
 * Receive an incoming control message.
 */
static int
ng_gif_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct ng_mesg *resp = NULL;
        int error = 0;
        struct ng_mesg *msg;

        NGI_GET_MSG(item, msg);
        switch (msg->header.typecookie) {
        case NGM_GIF_COOKIE:
                switch (msg->header.cmd) {
                case NGM_GIF_GET_IFNAME:
                        NG_MKRESPONSE(resp, msg, IFNAMSIZ, M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                break;
                        }
                        strlcpy(resp->data, priv->ifp->if_xname, IFNAMSIZ);
                        break;
                case NGM_GIF_GET_IFINDEX:
                        NG_MKRESPONSE(resp, msg, sizeof(u_int32_t), M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                break;
                        }
                        *((u_int32_t *)resp->data) = priv->ifp->if_index;
                        break;
                default:
                        error = EINVAL;
                        break;
                }
                break;
        default:
                error = EINVAL;
                break;
        }
        NG_RESPOND_MSG(error, node, item, resp);
        NG_FREE_MSG(msg);
        return (error);
}

/*
 * Receive data on a hook.
 */
static int
ng_gif_rcvdata(hook_p hook, item_p item)
{
        const node_p node = NG_HOOK_NODE(hook);
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct mbuf *m;

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

        if (hook == priv->lower)
                return ng_gif_rcv_lower(node, m);
        panic("%s: weird hook", __func__);
}

/*
 * Handle an mbuf received on the "lower" hook.
 */
static int
ng_gif_rcv_lower(node_p node, struct mbuf *m)
{
        struct sockaddr dst;
        const priv_p priv = NG_NODE_PRIVATE(node);

        bzero(&dst, sizeof(dst));

        /* Make sure header is fully pulled up */
        if (m->m_pkthdr.len < sizeof(sa_family_t)) {
                NG_FREE_M(m);
                return (EINVAL);
        }
        if (m->m_len < sizeof(sa_family_t)
            && (m = m_pullup(m, sizeof(sa_family_t))) == NULL) {
                return (ENOBUFS);
        }

        dst.sa_family = *mtod(m, sa_family_t *);
        m_adj(m, sizeof(sa_family_t));

        /* Send it on its way */
        /*
         * XXX: gif_output only uses dst for the family and passes the
         * fourth argument (rt) to in{,6}_gif_output which ignore it.
         * If this changes ng_gif will probably break.
         */
        return gif_output(priv->ifp, m, &dst, NULL);
}

/*
 * Shutdown node. This resets the node but does not remove it
 * unless the REALLY_DIE flag is set.
 */
static int
ng_gif_shutdown(node_p node)
{
        const priv_p priv = NG_NODE_PRIVATE(node);

        if (node->nd_flags & NGF_REALLY_DIE) {
                /*
                 * WE came here because the gif interface is being destroyed,
                 * so stop being persistant.
                 * Actually undo all the things we did on creation.
                 * Assume the ifp has already been freed.
                 */
                NG_NODE_SET_PRIVATE(node, NULL);
                kfree(priv, M_NETGRAPH);
                NG_NODE_UNREF(node);    /* free node itself */
                return (0);
        }
        NG_NODE_REVIVE(node);           /* Signal ng_rmnode we are persisant */
        return (0);
}

/*
 * Hook disconnection.
 */
static int
ng_gif_disconnect(hook_p hook)
{
        const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));

        if (hook == priv->lower) {
                priv->lower = NULL;
                priv->lowerOrphan = 0;
        } else 
                panic("%s: weird hook", __func__);
        if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
            && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
                ng_rmnode_self(NG_HOOK_NODE(hook));     /* reset node */

        return (0);
}

/******************************************************************
                        INITIALIZATION
******************************************************************/

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

        s = splnet();
        switch (event) {
        case MOD_LOAD:

                /* Register function hooks */
                if (ng_gif_attach_p != NULL) {
                        error = EEXIST;
                        break;
                }
                ng_gif_attach_p = ng_gif_attach;
                ng_gif_detach_p = ng_gif_detach;
                ng_gif_input_p = ng_gif_input;
                ng_gif_input_orphan_p = ng_gif_input_orphan;

                /* Create nodes for any already-existing gif interfaces */
                ifnet_lock();
                TAILQ_FOREACH(ifp, &ifnetlist, if_link) {
                        if (ifp->if_type == IFT_GIF)
                                ng_gif_attach(ifp);
                }
                ifnet_unlock();
                break;

        case MOD_UNLOAD:

                /*
                 * Note that the base code won't try to unload us until
                 * all nodes have been removed, and that can't happen
                 * until all gif interfaces are destroyed. In any
                 * case, we know there are no nodes left if the action
                 * is MOD_UNLOAD, so there's no need to detach any nodes.
                 *
                 * XXX: what about manual unloads?!?
                 */

                /* Unregister function hooks */
                ng_gif_attach_p = NULL;
                ng_gif_detach_p = NULL;
                ng_gif_input_p = NULL;
                ng_gif_input_orphan_p = NULL;
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }
        splx(s);
        return (error);
}