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root/net/ipv4/fib_rules.c

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DEFINITIONS

This source file includes following definitions.
  1. fib_rules_tclass
  2. fib_lookup
  3. fib4_rule_action
  4. fib4_rule_match
  5. fib_empty_table
  6. fib4_rule_configure
  7. fib4_rule_compare
  8. fib4_rule_fill
  9. fib4_rule_default_pref
  10. fib4_rule_nlmsg_payload
  11. fib4_rule_flush_cache
  12. fib_default_rules_init
  13. fib4_rules_init
  14. fib4_rules_exit

/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              IPv4 Forwarding Information Base: policy rules.
 *
 * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
 *              Thomas Graf <tgraf@suug.ch>
 *
 *              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; either version
 *              2 of the License, or (at your option) any later version.
 *
 * Fixes:
 *              Rani Assaf      :       local_rule cannot be deleted
 *              Marc Boucher    :       routing by fwmark
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/netlink.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/rcupdate.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/tcp.h>
#include <net/ip_fib.h>
#include <net/fib_rules.h>

struct fib4_rule
{
        struct fib_rule         common;
        u8                      dst_len;
        u8                      src_len;
        u8                      tos;
        __be32                  src;
        __be32                  srcmask;
        __be32                  dst;
        __be32                  dstmask;
#ifdef CONFIG_NET_CLS_ROUTE
        u32                     tclassid;
#endif
};

#ifdef CONFIG_NET_CLS_ROUTE
u32 fib_rules_tclass(struct fib_result *res)
{
        return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
}
#endif

int fib_lookup(struct net *net, struct flowi *flp, struct fib_result *res)
{
        struct fib_lookup_arg arg = {
                .result = res,
        };
        int err;

        err = fib_rules_lookup(net->ipv4.rules_ops, flp, 0, &arg);
        res->r = arg.rule;

        return err;
}

static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
                            int flags, struct fib_lookup_arg *arg)
{
        int err = -EAGAIN;
        struct 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;
        }

        if ((tbl = fib_get_table(rule->fr_net, rule->table)) == NULL)
                goto errout;

        err = tbl->tb_lookup(tbl, flp, (struct fib_result *) arg->result);
        if (err > 0)
                err = -EAGAIN;
errout:
        return err;
}


static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
{
        struct fib4_rule *r = (struct fib4_rule *) rule;
        __be32 daddr = fl->fl4_dst;
        __be32 saddr = fl->fl4_src;

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

        if (r->tos && (r->tos != fl->fl4_tos))
                return 0;

        return 1;
}

static struct fib_table *fib_empty_table(struct net *net)
{
        u32 id;

        for (id = 1; id <= RT_TABLE_MAX; id++)
                if (fib_get_table(net, id) == NULL)
                        return fib_new_table(net, id);
        return NULL;
}

static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {
        FRA_GENERIC_POLICY,
        [FRA_FLOW]      = { .type = NLA_U32 },
};

static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,
                               struct nlmsghdr *nlh, struct fib_rule_hdr *frh,
                               struct nlattr **tb)
{
        struct net *net = sock_net(skb->sk);
        int err = -EINVAL;
        struct fib4_rule *rule4 = (struct fib4_rule *) rule;

        if (frh->tos & ~IPTOS_TOS_MASK)
                goto errout;

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

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

                        rule->table = table->tb_id;
                }
        }

        if (frh->src_len)
                rule4->src = nla_get_be32(tb[FRA_SRC]);

        if (frh->dst_len)
                rule4->dst = nla_get_be32(tb[FRA_DST]);

#ifdef CONFIG_NET_CLS_ROUTE
        if (tb[FRA_FLOW])
                rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
#endif

        rule4->src_len = frh->src_len;
        rule4->srcmask = inet_make_mask(rule4->src_len);
        rule4->dst_len = frh->dst_len;
        rule4->dstmask = inet_make_mask(rule4->dst_len);
        rule4->tos = frh->tos;

        err = 0;
errout:
        return err;
}

static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
                             struct nlattr **tb)
{
        struct fib4_rule *rule4 = (struct fib4_rule *) rule;

        if (frh->src_len && (rule4->src_len != frh->src_len))
                return 0;

        if (frh->dst_len && (rule4->dst_len != frh->dst_len))
                return 0;

        if (frh->tos && (rule4->tos != frh->tos))
                return 0;

#ifdef CONFIG_NET_CLS_ROUTE
        if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
                return 0;
#endif

        if (frh->src_len && (rule4->src != nla_get_be32(tb[FRA_SRC])))
                return 0;

        if (frh->dst_len && (rule4->dst != nla_get_be32(tb[FRA_DST])))
                return 0;

        return 1;
}

static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,
                          struct nlmsghdr *nlh, struct fib_rule_hdr *frh)
{
        struct fib4_rule *rule4 = (struct fib4_rule *) rule;

        frh->family = AF_INET;
        frh->dst_len = rule4->dst_len;
        frh->src_len = rule4->src_len;
        frh->tos = rule4->tos;

        if (rule4->dst_len)
                NLA_PUT_BE32(skb, FRA_DST, rule4->dst);

        if (rule4->src_len)
                NLA_PUT_BE32(skb, FRA_SRC, rule4->src);

#ifdef CONFIG_NET_CLS_ROUTE
        if (rule4->tclassid)
                NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
#endif
        return 0;

nla_put_failure:
        return -ENOBUFS;
}

static u32 fib4_rule_default_pref(struct fib_rules_ops *ops)
{
        struct list_head *pos;
        struct fib_rule *rule;

        if (!list_empty(&ops->rules_list)) {
                pos = ops->rules_list.next;
                if (pos->next != &ops->rules_list) {
                        rule = list_entry(pos->next, struct fib_rule, list);
                        if (rule->pref)
                                return rule->pref - 1;
                }
        }

        return 0;
}

static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
{
        return nla_total_size(4) /* dst */
               + nla_total_size(4) /* src */
               + nla_total_size(4); /* flow */
}

static void fib4_rule_flush_cache(struct fib_rules_ops *ops)
{
        rt_cache_flush(ops->fro_net, -1);
}

static struct fib_rules_ops fib4_rules_ops_template = {
        .family         = AF_INET,
        .rule_size      = sizeof(struct fib4_rule),
        .addr_size      = sizeof(u32),
        .action         = fib4_rule_action,
        .match          = fib4_rule_match,
        .configure      = fib4_rule_configure,
        .compare        = fib4_rule_compare,
        .fill           = fib4_rule_fill,
        .default_pref   = fib4_rule_default_pref,
        .nlmsg_payload  = fib4_rule_nlmsg_payload,
        .flush_cache    = fib4_rule_flush_cache,
        .nlgroup        = RTNLGRP_IPV4_RULE,
        .policy         = fib4_rule_policy,
        .owner          = THIS_MODULE,
};

static int fib_default_rules_init(struct fib_rules_ops *ops)
{
        int err;

        err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, FIB_RULE_PERMANENT);
        if (err < 0)
                return err;
        err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);
        if (err < 0)
                return err;
        err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);
        if (err < 0)
                return err;
        return 0;
}

int __net_init fib4_rules_init(struct net *net)
{
        int err;
        struct fib_rules_ops *ops;

        ops = kmemdup(&fib4_rules_ops_template, sizeof(*ops), GFP_KERNEL);
        if (ops == NULL)
                return -ENOMEM;
        INIT_LIST_HEAD(&ops->rules_list);
        ops->fro_net = net;

        fib_rules_register(ops);

        err = fib_default_rules_init(ops);
        if (err < 0)
                goto fail;
        net->ipv4.rules_ops = ops;
        return 0;

fail:
        /* also cleans all rules already added */
        fib_rules_unregister(ops);
        kfree(ops);
        return err;
}

void __net_exit fib4_rules_exit(struct net *net)
{
        fib_rules_unregister(net->ipv4.rules_ops);
        kfree(net->ipv4.rules_ops);
}

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