dn_rules.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 Routing Forwarding Information Base (Rules)
 *
 * Author:      Steve Whitehouse <[email protected]>
 *              Mostly copied from Alexey Kuznetsov's ipv4/fib_rules.c
 *
 *
 * Changes:
 *              Steve Whitehouse <[email protected]>
 *              Updated for Thomas Graf's generic rules
 *
 */
#include <linux/net.h>
#include <linux/init.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/netdevice.h>
#include <linux/spinlock.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <net/neighbour.h>
#include <net/dst.h>
#include <net/flow.h>
#include <net/fib_rules.h>
#include <net/dn.h>
#include <net/dn_fib.h>
#include <net/dn_neigh.h>
#include <net/dn_dev.h>
#include <net/dn_route.h>

static struct fib_rules_ops *dn_fib_rules_ops;

struct dn_fib_rule
{
    struct fib_rule     common;
    unsigned char       dst_len;
    unsigned char       src_len;
    __le16          src;
    __le16          srcmask;
    __le16          dst;
    __le16          dstmask;
    __le16          srcmap;
    u8          flags;
};


int dn_fib_lookup(struct flowidn *flp, struct dn_fib_res *res)
{
    struct fib_lookup_arg arg = {
        .result = res,
    };
    int err;

    err = fib_rules_lookup(dn_fib_rules_ops,
                   flowidn_to_flowi(flp), 0, &arg);
    res->r = arg.rule;

    return err;
}

static int dn_fib_rule_action(struct fib_rule *rule, struct flowi *flp,
                  int flags, struct fib_lookup_arg *arg)
{
    struct flowidn *fld = &flp->u.dn;
    int err = -EAGAIN;
    struct dn_fib_table *tbl;

    switch(rule->action) {
    case FR_ACT_TO_TBL:
        break;

    case FR_ACT_UNREACHABLE:
        err = -ENETUNREACH;
        goto errout;

    case FR_ACT_PROHIBIT:
        err = -EACCES;
        goto errout;

    case FR_ACT_BLACKHOLE:
    default:
        err = -EINVAL;
        goto errout;
    }

    tbl = dn_fib_get_table(rule->table, 0);
    if (tbl == NULL)
        goto errout;

    err = tbl->lookup(tbl, fld, (struct dn_fib_res *)arg->result);
    if (err > 0)
        err = -EAGAIN;
errout:
    return err;
}

static const struct nla_policy dn_fib_rule_policy[FRA_MAX+1] = {
    FRA_GENERIC_POLICY,
};

static int dn_fib_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
{
    struct dn_fib_rule *r = (struct dn_fib_rule *)rule;
    struct flowidn *fld = &fl->u.dn;
    __le16 daddr = fld->daddr;
    __le16 saddr = fld->saddr;

    if (((saddr ^ r->src) & r->srcmask) ||
        ((daddr ^ r->dst) & r->dstmask))
        return 0;

    return 1;
}

static int dn_fib_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
                 struct fib_rule_hdr *frh,
                 struct nlattr **tb)
{
    int err = -EINVAL;
    struct dn_fib_rule *r = (struct dn_fib_rule *)rule;

    if (frh->tos)
        goto  errout;

    if (rule->table == RT_TABLE_UNSPEC) {
        if (rule->action == FR_ACT_TO_TBL) {
            struct dn_fib_table *table;

            table = dn_fib_empty_table();
            if (table == NULL) {
                err = -ENOBUFS;
                goto errout;
            }

            rule->table = table->n;
        }
    }

    if (frh->src_len)
        r->src = nla_get_le16(tb[FRA_SRC]);

    if (frh->dst_len)
        r->dst = nla_get_le16(tb[FRA_DST]);

    r->src_len = frh->src_len;
    r->srcmask = dnet_make_mask(r->src_len);
    r->dst_len = frh->dst_len;
    r->dstmask = dnet_make_mask(r->dst_len);
    err = 0;
errout:
    return err;
}

static int dn_fib_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
                   struct nlattr **tb)
{
    struct dn_fib_rule *r = (struct dn_fib_rule *)rule;

    if (frh->src_len && (r->src_len != frh->src_len))
        return 0;

    if (frh->dst_len && (r->dst_len != frh->dst_len))
        return 0;

    if (frh->src_len && (r->src != nla_get_le16(tb[FRA_SRC])))
        return 0;

    if (frh->dst_len && (r->dst != nla_get_le16(tb[FRA_DST])))
        return 0;

    return 1;
}

unsigned int dnet_addr_type(__le16 addr)
{
    struct flowidn fld = { .daddr = addr };
    struct dn_fib_res res;
    unsigned int ret = RTN_UNICAST;
    struct dn_fib_table *tb = dn_fib_get_table(RT_TABLE_LOCAL, 0);

    res.r = NULL;

    if (tb) {
        if (!tb->lookup(tb, &fld, &res)) {
            ret = res.type;
            dn_fib_res_put(&res);
        }
    }
    return ret;
}

static int dn_fib_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
                struct fib_rule_hdr *frh)
{
    struct dn_fib_rule *r = (struct dn_fib_rule *)rule;

    frh->dst_len = r->dst_len;
    frh->src_len = r->src_len;
    frh->tos = 0;

    if ((r->dst_len &&
         nla_put_le16(skb, FRA_DST, r->dst)) ||
        (r->src_len &&
         nla_put_le16(skb, FRA_SRC, r->src)))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -ENOBUFS;
}

static void dn_fib_rule_flush_cache(struct fib_rules_ops *ops)
{
    dn_rt_cache_flush(-1);
}

static const struct fib_rules_ops __net_initconst dn_fib_rules_ops_template = {
    .family     = AF_DECnet,
    .rule_size  = sizeof(struct dn_fib_rule),
    .addr_size  = sizeof(u16),
    .action     = dn_fib_rule_action,
    .match      = dn_fib_rule_match,
    .configure  = dn_fib_rule_configure,
    .compare    = dn_fib_rule_compare,
    .fill       = dn_fib_rule_fill,
    .default_pref   = fib_default_rule_pref,
    .flush_cache    = dn_fib_rule_flush_cache,
    .nlgroup    = RTNLGRP_DECnet_RULE,
    .policy     = dn_fib_rule_policy,
    .owner      = THIS_MODULE,
    .fro_net    = &init_net,
};

void __init dn_fib_rules_init(void)
{
    dn_fib_rules_ops =
        fib_rules_register(&dn_fib_rules_ops_template, &init_net);
    BUG_ON(IS_ERR(dn_fib_rules_ops));
    BUG_ON(fib_default_rule_add(dn_fib_rules_ops, 0x7fff,
                        RT_TABLE_MAIN, 0));
}

void __exit dn_fib_rules_cleanup(void)
{
    fib_rules_unregister(dn_fib_rules_ops);
    rcu_barrier();
}