dn_neigh.c

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/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Neighbour Functions (Adjacency Database and
 *                                                        On-Ethernet Cache)
 *
 * Author:      Steve Whitehouse <[email protected]>
 *
 *
 * Changes:
 *     Steve Whitehouse     : Fixed router listing routine
 *     Steve Whitehouse     : Added error_report functions
 *     Steve Whitehouse     : Added default router detection
 *     Steve Whitehouse     : Hop counts in outgoing messages
 *     Steve Whitehouse     : Fixed src/dst in outgoing messages so
 *                            forwarding now stands a good chance of
 *                            working.
 *     Steve Whitehouse     : Fixed neighbour states (for now anyway).
 *     Steve Whitehouse     : Made error_report functions dummies. This
 *                            is not the right place to return skbs.
 *     Steve Whitehouse     : Convert to seq_file
 *
 */

#include <linux/net.h>
#include <linux/module.h>
#include <linux/socket.h>
#include <linux/if_arp.h>
#include <linux/slab.h>
#include <linux/if_ether.h>
#include <linux/init.h>
#include <linux/proc_fs.h>
#include <linux/string.h>
#include <linux/netfilter_decnet.h>
#include <linux/spinlock.h>
#include <linux/seq_file.h>
#include <linux/rcupdate.h>
#include <linux/jhash.h>
#include <linux/atomic.h>
#include <net/net_namespace.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/dn.h>
#include <net/dn_dev.h>
#include <net/dn_neigh.h>
#include <net/dn_route.h>

static int dn_neigh_construct(struct neighbour *);
static void dn_long_error_report(struct neighbour *, struct sk_buff *);
static void dn_short_error_report(struct neighbour *, struct sk_buff *);
static int dn_long_output(struct neighbour *, struct sk_buff *);
static int dn_short_output(struct neighbour *, struct sk_buff *);
static int dn_phase3_output(struct neighbour *, struct sk_buff *);


/*
 * For talking to broadcast devices: Ethernet & PPP
 */
static const struct neigh_ops dn_long_ops = {
    .family =       AF_DECnet,
    .error_report =     dn_long_error_report,
    .output =       dn_long_output,
    .connected_output = dn_long_output,
};

/*
 * For talking to pointopoint and multidrop devices: DDCMP and X.25
 */
static const struct neigh_ops dn_short_ops = {
    .family =       AF_DECnet,
    .error_report =     dn_short_error_report,
    .output =       dn_short_output,
    .connected_output = dn_short_output,
};

/*
 * For talking to DECnet phase III nodes
 */
static const struct neigh_ops dn_phase3_ops = {
    .family =       AF_DECnet,
    .error_report =     dn_short_error_report, /* Can use short version here */
    .output =       dn_phase3_output,
    .connected_output = dn_phase3_output,
};

static u32 dn_neigh_hash(const void *pkey,
             const struct net_device *dev,
             __u32 *hash_rnd)
{
    return jhash_2words(*(__u16 *)pkey, 0, hash_rnd[0]);
}

struct neigh_table dn_neigh_table = {
    .family =           PF_DECnet,
    .entry_size =           sizeof(struct dn_neigh),
    .key_len =          sizeof(__le16),
    .hash =             dn_neigh_hash,
    .constructor =          dn_neigh_construct,
    .id =               "dn_neigh_cache",
    .parms ={
        .tbl =          &dn_neigh_table,
        .base_reachable_time =  30 * HZ,
        .retrans_time = 1 * HZ,
        .gc_staletime = 60 * HZ,
        .reachable_time =       30 * HZ,
        .delay_probe_time = 5 * HZ,
        .queue_len_bytes =  64*1024,
        .ucast_probes = 0,
        .app_probes =       0,
        .mcast_probes = 0,
        .anycast_delay =    0,
        .proxy_delay =      0,
        .proxy_qlen =       0,
        .locktime =     1 * HZ,
    },
    .gc_interval =          30 * HZ,
    .gc_thresh1 =           128,
    .gc_thresh2 =           512,
    .gc_thresh3 =           1024,
};

static int dn_neigh_construct(struct neighbour *neigh)
{
    struct net_device *dev = neigh->dev;
    struct dn_neigh *dn = (struct dn_neigh *)neigh;
    struct dn_dev *dn_db;
    struct neigh_parms *parms;

    rcu_read_lock();
    dn_db = rcu_dereference(dev->dn_ptr);
    if (dn_db == NULL) {
        rcu_read_unlock();
        return -EINVAL;
    }

    parms = dn_db->neigh_parms;
    if (!parms) {
        rcu_read_unlock();
        return -EINVAL;
    }

    __neigh_parms_put(neigh->parms);
    neigh->parms = neigh_parms_clone(parms);

    if (dn_db->use_long)
        neigh->ops = &dn_long_ops;
    else
        neigh->ops = &dn_short_ops;
    rcu_read_unlock();

    if (dn->flags & DN_NDFLAG_P3)
        neigh->ops = &dn_phase3_ops;

    neigh->nud_state = NUD_NOARP;
    neigh->output = neigh->ops->connected_output;

    if ((dev->type == ARPHRD_IPGRE) || (dev->flags & IFF_POINTOPOINT))
        memcpy(neigh->ha, dev->broadcast, dev->addr_len);
    else if ((dev->type == ARPHRD_ETHER) || (dev->type == ARPHRD_LOOPBACK))
        dn_dn2eth(neigh->ha, dn->addr);
    else {
        net_dbg_ratelimited("Trying to create neigh for hw %d\n",
                    dev->type);
        return -EINVAL;
    }

    /*
     * Make an estimate of the remote block size by assuming that its
     * two less then the device mtu, which it true for ethernet (and
     * other things which support long format headers) since there is
     * an extra length field (of 16 bits) which isn't part of the
     * ethernet headers and which the DECnet specs won't admit is part
     * of the DECnet routing headers either.
     *
     * If we over estimate here its no big deal, the NSP negotiations
     * will prevent us from sending packets which are too large for the
     * remote node to handle. In any case this figure is normally updated
     * by a hello message in most cases.
     */
    dn->blksize = dev->mtu - 2;

    return 0;
}

static void dn_long_error_report(struct neighbour *neigh, struct sk_buff *skb)
{
    printk(KERN_DEBUG "dn_long_error_report: called\n");
    kfree_skb(skb);
}


static void dn_short_error_report(struct neighbour *neigh, struct sk_buff *skb)
{
    printk(KERN_DEBUG "dn_short_error_report: called\n");
    kfree_skb(skb);
}

static int dn_neigh_output_packet(struct sk_buff *skb)
{
    struct dst_entry *dst = skb_dst(skb);
    struct dn_route *rt = (struct dn_route *)dst;
    struct neighbour *neigh = rt->n;
    struct net_device *dev = neigh->dev;
    char mac_addr[ETH_ALEN];
    unsigned int seq;
    int err;

    dn_dn2eth(mac_addr, rt->rt_local_src);
    do {
        seq = read_seqbegin(&neigh->ha_lock);
        err = dev_hard_header(skb, dev, ntohs(skb->protocol),
                      neigh->ha, mac_addr, skb->len);
    } while (read_seqretry(&neigh->ha_lock, seq));

    if (err >= 0)
        err = dev_queue_xmit(skb);
    else {
        kfree_skb(skb);
        err = -EINVAL;
    }
    return err;
}

static int dn_long_output(struct neighbour *neigh, struct sk_buff *skb)
{
    struct net_device *dev = neigh->dev;
    int headroom = dev->hard_header_len + sizeof(struct dn_long_packet) + 3;
    unsigned char *data;
    struct dn_long_packet *lp;
    struct dn_skb_cb *cb = DN_SKB_CB(skb);


    if (skb_headroom(skb) < headroom) {
        struct sk_buff *skb2 = skb_realloc_headroom(skb, headroom);
        if (skb2 == NULL) {
            net_crit_ratelimited("dn_long_output: no memory\n");
            kfree_skb(skb);
            return -ENOBUFS;
        }
        consume_skb(skb);
        skb = skb2;
        net_info_ratelimited("dn_long_output: Increasing headroom\n");
    }

    data = skb_push(skb, sizeof(struct dn_long_packet) + 3);
    lp = (struct dn_long_packet *)(data+3);

    *((__le16 *)data) = cpu_to_le16(skb->len - 2);
    *(data + 2) = 1 | DN_RT_F_PF; /* Padding */

    lp->msgflg   = DN_RT_PKT_LONG|(cb->rt_flags&(DN_RT_F_IE|DN_RT_F_RQR|DN_RT_F_RTS));
    lp->d_area   = lp->d_subarea = 0;
    dn_dn2eth(lp->d_id, cb->dst);
    lp->s_area   = lp->s_subarea = 0;
    dn_dn2eth(lp->s_id, cb->src);
    lp->nl2      = 0;
    lp->visit_ct = cb->hops & 0x3f;
    lp->s_class  = 0;
    lp->pt       = 0;

    skb_reset_network_header(skb);

    return NF_HOOK(NFPROTO_DECNET, NF_DN_POST_ROUTING, skb, NULL,
               neigh->dev, dn_neigh_output_packet);
}

static int dn_short_output(struct neighbour *neigh, struct sk_buff *skb)
{
    struct net_device *dev = neigh->dev;
    int headroom = dev->hard_header_len + sizeof(struct dn_short_packet) + 2;
    struct dn_short_packet *sp;
    unsigned char *data;
    struct dn_skb_cb *cb = DN_SKB_CB(skb);


    if (skb_headroom(skb) < headroom) {
        struct sk_buff *skb2 = skb_realloc_headroom(skb, headroom);
        if (skb2 == NULL) {
            net_crit_ratelimited("dn_short_output: no memory\n");
            kfree_skb(skb);
            return -ENOBUFS;
        }
        consume_skb(skb);
        skb = skb2;
        net_info_ratelimited("dn_short_output: Increasing headroom\n");
    }

    data = skb_push(skb, sizeof(struct dn_short_packet) + 2);
    *((__le16 *)data) = cpu_to_le16(skb->len - 2);
    sp = (struct dn_short_packet *)(data+2);

    sp->msgflg     = DN_RT_PKT_SHORT|(cb->rt_flags&(DN_RT_F_RQR|DN_RT_F_RTS));
    sp->dstnode    = cb->dst;
    sp->srcnode    = cb->src;
    sp->forward    = cb->hops & 0x3f;

    skb_reset_network_header(skb);

    return NF_HOOK(NFPROTO_DECNET, NF_DN_POST_ROUTING, skb, NULL,
               neigh->dev, dn_neigh_output_packet);
}

/*
 * Phase 3 output is the same is short output, execpt that
 * it clears the area bits before transmission.
 */
static int dn_phase3_output(struct neighbour *neigh, struct sk_buff *skb)
{
    struct net_device *dev = neigh->dev;
    int headroom = dev->hard_header_len + sizeof(struct dn_short_packet) + 2;
    struct dn_short_packet *sp;
    unsigned char *data;
    struct dn_skb_cb *cb = DN_SKB_CB(skb);

    if (skb_headroom(skb) < headroom) {
        struct sk_buff *skb2 = skb_realloc_headroom(skb, headroom);
        if (skb2 == NULL) {
            net_crit_ratelimited("dn_phase3_output: no memory\n");
            kfree_skb(skb);
            return -ENOBUFS;
        }
        consume_skb(skb);
        skb = skb2;
        net_info_ratelimited("dn_phase3_output: Increasing headroom\n");
    }

    data = skb_push(skb, sizeof(struct dn_short_packet) + 2);
    *((__le16 *)data) = cpu_to_le16(skb->len - 2);
    sp = (struct dn_short_packet *)(data + 2);

    sp->msgflg   = DN_RT_PKT_SHORT|(cb->rt_flags&(DN_RT_F_RQR|DN_RT_F_RTS));
    sp->dstnode  = cb->dst & cpu_to_le16(0x03ff);
    sp->srcnode  = cb->src & cpu_to_le16(0x03ff);
    sp->forward  = cb->hops & 0x3f;

    skb_reset_network_header(skb);

    return NF_HOOK(NFPROTO_DECNET, NF_DN_POST_ROUTING, skb, NULL,
               neigh->dev, dn_neigh_output_packet);
}

/*
 * Unfortunately, the neighbour code uses the device in its hash
 * function, so we don't get any advantage from it. This function
 * basically does a neigh_lookup(), but without comparing the device
 * field. This is required for the On-Ethernet cache
 */

/*
 * Pointopoint link receives a hello message
 */
void dn_neigh_pointopoint_hello(struct sk_buff *skb)
{
    kfree_skb(skb);
}

/*
 * Ethernet router hello message received
 */
int dn_neigh_router_hello(struct sk_buff *skb)
{
    struct rtnode_hello_message *msg = (struct rtnode_hello_message *)skb->data;

    struct neighbour *neigh;
    struct dn_neigh *dn;
    struct dn_dev *dn_db;
    __le16 src;

    src = dn_eth2dn(msg->id);

    neigh = __neigh_lookup(&dn_neigh_table, &src, skb->dev, 1);

    dn = (struct dn_neigh *)neigh;

    if (neigh) {
        write_lock(&neigh->lock);

        neigh->used = jiffies;
        dn_db = rcu_dereference(neigh->dev->dn_ptr);

        if (!(neigh->nud_state & NUD_PERMANENT)) {
            neigh->updated = jiffies;

            if (neigh->dev->type == ARPHRD_ETHER)
                memcpy(neigh->ha, &eth_hdr(skb)->h_source, ETH_ALEN);

            dn->blksize  = le16_to_cpu(msg->blksize);
            dn->priority = msg->priority;

            dn->flags &= ~DN_NDFLAG_P3;

            switch (msg->iinfo & DN_RT_INFO_TYPE) {
            case DN_RT_INFO_L1RT:
                dn->flags &=~DN_NDFLAG_R2;
                dn->flags |= DN_NDFLAG_R1;
                break;
            case DN_RT_INFO_L2RT:
                dn->flags |= DN_NDFLAG_R2;
            }
        }

        /* Only use routers in our area */
        if ((le16_to_cpu(src)>>10) == (le16_to_cpu((decnet_address))>>10)) {
            if (!dn_db->router) {
                dn_db->router = neigh_clone(neigh);
            } else {
                if (msg->priority > ((struct dn_neigh *)dn_db->router)->priority)
                    neigh_release(xchg(&dn_db->router, neigh_clone(neigh)));
            }
        }
        write_unlock(&neigh->lock);
        neigh_release(neigh);
    }

    kfree_skb(skb);
    return 0;
}

/*
 * Endnode hello message received
 */
int dn_neigh_endnode_hello(struct sk_buff *skb)
{
    struct endnode_hello_message *msg = (struct endnode_hello_message *)skb->data;
    struct neighbour *neigh;
    struct dn_neigh *dn;
    __le16 src;

    src = dn_eth2dn(msg->id);

    neigh = __neigh_lookup(&dn_neigh_table, &src, skb->dev, 1);

    dn = (struct dn_neigh *)neigh;

    if (neigh) {
        write_lock(&neigh->lock);

        neigh->used = jiffies;

        if (!(neigh->nud_state & NUD_PERMANENT)) {
            neigh->updated = jiffies;

            if (neigh->dev->type == ARPHRD_ETHER)
                memcpy(neigh->ha, &eth_hdr(skb)->h_source, ETH_ALEN);
            dn->flags   &= ~(DN_NDFLAG_R1 | DN_NDFLAG_R2);
            dn->blksize  = le16_to_cpu(msg->blksize);
            dn->priority = 0;
        }

        write_unlock(&neigh->lock);
        neigh_release(neigh);
    }

    kfree_skb(skb);
    return 0;
}

static char *dn_find_slot(char *base, int max, int priority)
{
    int i;
    unsigned char *min = NULL;

    base += 6; /* skip first id */

    for(i = 0; i < max; i++) {
        if (!min || (*base < *min))
            min = base;
        base += 7; /* find next priority */
    }

    if (!min)
        return NULL;

    return (*min < priority) ? (min - 6) : NULL;
}

struct elist_cb_state {
    struct net_device *dev;
    unsigned char *ptr;
    unsigned char *rs;
    int t, n;
};

static void neigh_elist_cb(struct neighbour *neigh, void *_info)
{
    struct elist_cb_state *s = _info;
    struct dn_neigh *dn;

    if (neigh->dev != s->dev)
        return;

    dn = (struct dn_neigh *) neigh;
    if (!(dn->flags & (DN_NDFLAG_R1|DN_NDFLAG_R2)))
        return;

    if (s->t == s->n)
        s->rs = dn_find_slot(s->ptr, s->n, dn->priority);
    else
        s->t++;
    if (s->rs == NULL)
        return;

    dn_dn2eth(s->rs, dn->addr);
    s->rs += 6;
    *(s->rs) = neigh->nud_state & NUD_CONNECTED ? 0x80 : 0x0;
    *(s->rs) |= dn->priority;
    s->rs++;
}

int dn_neigh_elist(struct net_device *dev, unsigned char *ptr, int n)
{
    struct elist_cb_state state;

    state.dev = dev;
    state.t = 0;
    state.n = n;
    state.ptr = ptr;
    state.rs = ptr;

    neigh_for_each(&dn_neigh_table, neigh_elist_cb, &state);

    return state.t;
}


#ifdef CONFIG_PROC_FS

static inline void dn_neigh_format_entry(struct seq_file *seq,
                     struct neighbour *n)
{
    struct dn_neigh *dn = (struct dn_neigh *) n;
    char buf[DN_ASCBUF_LEN];

    read_lock(&n->lock);
    seq_printf(seq, "%-7s %s%s%s   %02x    %02d  %07ld %-8s\n",
           dn_addr2asc(le16_to_cpu(dn->addr), buf),
           (dn->flags&DN_NDFLAG_R1) ? "1" : "-",
           (dn->flags&DN_NDFLAG_R2) ? "2" : "-",
           (dn->flags&DN_NDFLAG_P3) ? "3" : "-",
           dn->n.nud_state,
           atomic_read(&dn->n.refcnt),
           dn->blksize,
           (dn->n.dev) ? dn->n.dev->name : "?");
    read_unlock(&n->lock);
}

static int dn_neigh_seq_show(struct seq_file *seq, void *v)
{
    if (v == SEQ_START_TOKEN) {
        seq_puts(seq, "Addr    Flags State Use Blksize Dev\n");
    } else {
        dn_neigh_format_entry(seq, v);
    }

    return 0;
}

static void *dn_neigh_seq_start(struct seq_file *seq, loff_t *pos)
{
    return neigh_seq_start(seq, pos, &dn_neigh_table,
                   NEIGH_SEQ_NEIGH_ONLY);
}

static const struct seq_operations dn_neigh_seq_ops = {
    .start = dn_neigh_seq_start,
    .next  = neigh_seq_next,
    .stop  = neigh_seq_stop,
    .show  = dn_neigh_seq_show,
};

static int dn_neigh_seq_open(struct inode *inode, struct file *file)
{
    return seq_open_net(inode, file, &dn_neigh_seq_ops,
                sizeof(struct neigh_seq_state));
}

static const struct file_operations dn_neigh_seq_fops = {
    .owner      = THIS_MODULE,
    .open       = dn_neigh_seq_open,
    .read       = seq_read,
    .llseek     = seq_lseek,
    .release    = seq_release_net,
};

#endif

void __init dn_neigh_init(void)
{
    neigh_table_init(&dn_neigh_table);
    proc_net_fops_create(&init_net, "decnet_neigh", S_IRUGO, &dn_neigh_seq_fops);
}

void __exit dn_neigh_cleanup(void)
{
    proc_net_remove(&init_net, "decnet_neigh");
    neigh_table_clear(&dn_neigh_table);
}