fib6_rules.c

Go to the documentation of this file.

/*
 * net/ipv6/fib6_rules.c    IPv6 Routing Policy Rules
 *
 * Copyright (C)2003-2006 Helsinki University of Technology
 * Copyright (C)2003-2006 USAGI/WIDE Project
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License as
 *  published by the Free Software Foundation, version 2.
 *
 * Authors
 *  Thomas Graf     <[email protected]>
 *  Ville Nuorvala      <[email protected]>
 */

#include <linux/netdevice.h>
#include <linux/export.h>

#include <net/fib_rules.h>
#include <net/ipv6.h>
#include <net/addrconf.h>
#include <net/ip6_route.h>
#include <net/netlink.h>

struct fib6_rule {
    struct fib_rule     common;
    struct rt6key       src;
    struct rt6key       dst;
    u8          tclass;
};

struct dst_entry *fib6_rule_lookup(struct net *net, struct flowi6 *fl6,
                   int flags, pol_lookup_t lookup)
{
    struct fib_lookup_arg arg = {
        .lookup_ptr = lookup,
        .flags = FIB_LOOKUP_NOREF,
    };

    fib_rules_lookup(net->ipv6.fib6_rules_ops,
             flowi6_to_flowi(fl6), flags, &arg);

    if (arg.result)
        return arg.result;

    dst_hold(&net->ipv6.ip6_null_entry->dst);
    return &net->ipv6.ip6_null_entry->dst;
}

static int fib6_rule_action(struct fib_rule *rule, struct flowi *flp,
                int flags, struct fib_lookup_arg *arg)
{
    struct flowi6 *flp6 = &flp->u.ip6;
    struct rt6_info *rt = NULL;
    struct fib6_table *table;
    struct net *net = rule->fr_net;
    pol_lookup_t lookup = arg->lookup_ptr;

    switch (rule->action) {
    case FR_ACT_TO_TBL:
        break;
    case FR_ACT_UNREACHABLE:
        rt = net->ipv6.ip6_null_entry;
        goto discard_pkt;
    default:
    case FR_ACT_BLACKHOLE:
        rt = net->ipv6.ip6_blk_hole_entry;
        goto discard_pkt;
    case FR_ACT_PROHIBIT:
        rt = net->ipv6.ip6_prohibit_entry;
        goto discard_pkt;
    }

    table = fib6_get_table(net, rule->table);
    if (table)
        rt = lookup(net, table, flp6, flags);

    if (rt != net->ipv6.ip6_null_entry) {
        struct fib6_rule *r = (struct fib6_rule *)rule;

        /*
         * If we need to find a source address for this traffic,
         * we check the result if it meets requirement of the rule.
         */
        if ((rule->flags & FIB_RULE_FIND_SADDR) &&
            r->src.plen && !(flags & RT6_LOOKUP_F_HAS_SADDR)) {
            struct in6_addr saddr;

            if (ipv6_dev_get_saddr(net,
                           ip6_dst_idev(&rt->dst)->dev,
                           &flp6->daddr,
                           rt6_flags2srcprefs(flags),
                           &saddr))
                goto again;
            if (!ipv6_prefix_equal(&saddr, &r->src.addr,
                           r->src.plen))
                goto again;
            flp6->saddr = saddr;
        }
        goto out;
    }
again:
    dst_release(&rt->dst);
    rt = NULL;
    goto out;

discard_pkt:
    dst_hold(&rt->dst);
out:
    arg->result = rt;
    return rt == NULL ? -EAGAIN : 0;
}


static int fib6_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
{
    struct fib6_rule *r = (struct fib6_rule *) rule;
    struct flowi6 *fl6 = &fl->u.ip6;

    if (r->dst.plen &&
        !ipv6_prefix_equal(&fl6->daddr, &r->dst.addr, r->dst.plen))
        return 0;

    /*
     * If FIB_RULE_FIND_SADDR is set and we do not have a
     * source address for the traffic, we defer check for
     * source address.
     */
    if (r->src.plen) {
        if (flags & RT6_LOOKUP_F_HAS_SADDR) {
            if (!ipv6_prefix_equal(&fl6->saddr, &r->src.addr,
                           r->src.plen))
                return 0;
        } else if (!(r->common.flags & FIB_RULE_FIND_SADDR))
            return 0;
    }

    if (r->tclass && r->tclass != ((ntohl(fl6->flowlabel) >> 20) & 0xff))
        return 0;

    return 1;
}

static const struct nla_policy fib6_rule_policy[FRA_MAX+1] = {
    FRA_GENERIC_POLICY,
};

static int fib6_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
                   struct fib_rule_hdr *frh,
                   struct nlattr **tb)
{
    int err = -EINVAL;
    struct net *net = sock_net(skb->sk);
    struct fib6_rule *rule6 = (struct fib6_rule *) rule;

    if (rule->action == FR_ACT_TO_TBL) {
        if (rule->table == RT6_TABLE_UNSPEC)
            goto errout;

        if (fib6_new_table(net, rule->table) == NULL) {
            err = -ENOBUFS;
            goto errout;
        }
    }

    if (frh->src_len)
        nla_memcpy(&rule6->src.addr, tb[FRA_SRC],
               sizeof(struct in6_addr));

    if (frh->dst_len)
        nla_memcpy(&rule6->dst.addr, tb[FRA_DST],
               sizeof(struct in6_addr));

    rule6->src.plen = frh->src_len;
    rule6->dst.plen = frh->dst_len;
    rule6->tclass = frh->tos;

    err = 0;
errout:
    return err;
}

static int fib6_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
                 struct nlattr **tb)
{
    struct fib6_rule *rule6 = (struct fib6_rule *) rule;

    if (frh->src_len && (rule6->src.plen != frh->src_len))
        return 0;

    if (frh->dst_len && (rule6->dst.plen != frh->dst_len))
        return 0;

    if (frh->tos && (rule6->tclass != frh->tos))
        return 0;

    if (frh->src_len &&
        nla_memcmp(tb[FRA_SRC], &rule6->src.addr, sizeof(struct in6_addr)))
        return 0;

    if (frh->dst_len &&
        nla_memcmp(tb[FRA_DST], &rule6->dst.addr, sizeof(struct in6_addr)))
        return 0;

    return 1;
}

static int fib6_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
              struct fib_rule_hdr *frh)
{
    struct fib6_rule *rule6 = (struct fib6_rule *) rule;

    frh->dst_len = rule6->dst.plen;
    frh->src_len = rule6->src.plen;
    frh->tos = rule6->tclass;

    if ((rule6->dst.plen &&
         nla_put(skb, FRA_DST, sizeof(struct in6_addr),
             &rule6->dst.addr)) ||
        (rule6->src.plen &&
         nla_put(skb, FRA_SRC, sizeof(struct in6_addr),
             &rule6->src.addr)))
        goto nla_put_failure;
    return 0;

nla_put_failure:
    return -ENOBUFS;
}

static u32 fib6_rule_default_pref(struct fib_rules_ops *ops)
{
    return 0x3FFF;
}

static size_t fib6_rule_nlmsg_payload(struct fib_rule *rule)
{
    return nla_total_size(16) /* dst */
           + nla_total_size(16); /* src */
}

static const struct fib_rules_ops __net_initconst fib6_rules_ops_template = {
    .family         = AF_INET6,
    .rule_size      = sizeof(struct fib6_rule),
    .addr_size      = sizeof(struct in6_addr),
    .action         = fib6_rule_action,
    .match          = fib6_rule_match,
    .configure      = fib6_rule_configure,
    .compare        = fib6_rule_compare,
    .fill           = fib6_rule_fill,
    .default_pref       = fib6_rule_default_pref,
    .nlmsg_payload      = fib6_rule_nlmsg_payload,
    .nlgroup        = RTNLGRP_IPV6_RULE,
    .policy         = fib6_rule_policy,
    .owner          = THIS_MODULE,
    .fro_net        = &init_net,
};

static int __net_init fib6_rules_net_init(struct net *net)
{
    struct fib_rules_ops *ops;
    int err = -ENOMEM;

    ops = fib_rules_register(&fib6_rules_ops_template, net);
    if (IS_ERR(ops))
        return PTR_ERR(ops);
    net->ipv6.fib6_rules_ops = ops;


    err = fib_default_rule_add(net->ipv6.fib6_rules_ops, 0,
                   RT6_TABLE_LOCAL, 0);
    if (err)
        goto out_fib6_rules_ops;

    err = fib_default_rule_add(net->ipv6.fib6_rules_ops,
                   0x7FFE, RT6_TABLE_MAIN, 0);
    if (err)
        goto out_fib6_rules_ops;

out:
    return err;

out_fib6_rules_ops:
    fib_rules_unregister(ops);
    goto out;
}

static void __net_exit fib6_rules_net_exit(struct net *net)
{
    fib_rules_unregister(net->ipv6.fib6_rules_ops);
}

static struct pernet_operations fib6_rules_net_ops = {
    .init = fib6_rules_net_init,
    .exit = fib6_rules_net_exit,
};

int __init fib6_rules_init(void)
{
    return register_pernet_subsys(&fib6_rules_net_ops);
}


void fib6_rules_cleanup(void)
{
    unregister_pernet_subsys(&fib6_rules_net_ops);
}