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root/net/core/fib_rules.c

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DEFINITIONS

This source file includes following definitions.
  1. fib_default_rule_add
  2. lookup_rules_ops
  3. rules_ops_put
  4. flush_route_cache
  5. fib_rules_register
  6. fib_rules_cleanup_ops
  7. fib_rules_unregister
  8. fib_rule_match
  9. fib_rules_lookup
  10. validate_rulemsg
  11. fib_nl_newrule
  12. fib_nl_delrule
  13. fib_rule_nlmsg_size
  14. fib_nl_fill_rule
  15. dump_rules
  16. fib_nl_dumprule
  17. notify_rule_change
  18. attach_rules
  19. detach_rules
  20. fib_rules_event
  21. fib_rules_net_init
  22. fib_rules_init

/*
 * net/core/fib_rules.c         Generic Routing Rules
 *
 *      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 <tgraf@suug.ch>
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <net/net_namespace.h>
#include <net/sock.h>
#include <net/fib_rules.h>

int fib_default_rule_add(struct fib_rules_ops *ops,
                         u32 pref, u32 table, u32 flags)
{
        struct fib_rule *r;

        r = kzalloc(ops->rule_size, GFP_KERNEL);
        if (r == NULL)
                return -ENOMEM;

        atomic_set(&r->refcnt, 1);
        r->action = FR_ACT_TO_TBL;
        r->pref = pref;
        r->table = table;
        r->flags = flags;
        r->fr_net = hold_net(ops->fro_net);

        /* The lock is not required here, the list in unreacheable
         * at the moment this function is called */
        list_add_tail(&r->list, &ops->rules_list);
        return 0;
}
EXPORT_SYMBOL(fib_default_rule_add);

static void notify_rule_change(int event, struct fib_rule *rule,
                               struct fib_rules_ops *ops, struct nlmsghdr *nlh,
                               u32 pid);

static struct fib_rules_ops *lookup_rules_ops(struct net *net, int family)
{
        struct fib_rules_ops *ops;

        rcu_read_lock();
        list_for_each_entry_rcu(ops, &net->rules_ops, list) {
                if (ops->family == family) {
                        if (!try_module_get(ops->owner))
                                ops = NULL;
                        rcu_read_unlock();
                        return ops;
                }
        }
        rcu_read_unlock();

        return NULL;
}

static void rules_ops_put(struct fib_rules_ops *ops)
{
        if (ops)
                module_put(ops->owner);
}

static void flush_route_cache(struct fib_rules_ops *ops)
{
        if (ops->flush_cache)
                ops->flush_cache(ops);
}

int fib_rules_register(struct fib_rules_ops *ops)
{
        int err = -EEXIST;
        struct fib_rules_ops *o;
        struct net *net;

        net = ops->fro_net;

        if (ops->rule_size < sizeof(struct fib_rule))
                return -EINVAL;

        if (ops->match == NULL || ops->configure == NULL ||
            ops->compare == NULL || ops->fill == NULL ||
            ops->action == NULL)
                return -EINVAL;

        spin_lock(&net->rules_mod_lock);
        list_for_each_entry(o, &net->rules_ops, list)
                if (ops->family == o->family)
                        goto errout;

        hold_net(net);
        list_add_tail_rcu(&ops->list, &net->rules_ops);
        err = 0;
errout:
        spin_unlock(&net->rules_mod_lock);

        return err;
}

EXPORT_SYMBOL_GPL(fib_rules_register);

void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
{
        struct fib_rule *rule, *tmp;

        list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
                list_del_rcu(&rule->list);
                fib_rule_put(rule);
        }
}
EXPORT_SYMBOL_GPL(fib_rules_cleanup_ops);

void fib_rules_unregister(struct fib_rules_ops *ops)
{
        struct net *net = ops->fro_net;

        spin_lock(&net->rules_mod_lock);
        list_del_rcu(&ops->list);
        fib_rules_cleanup_ops(ops);
        spin_unlock(&net->rules_mod_lock);

        synchronize_rcu();
        release_net(net);
}

EXPORT_SYMBOL_GPL(fib_rules_unregister);

static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
                          struct flowi *fl, int flags)
{
        int ret = 0;

        if (rule->ifindex && (rule->ifindex != fl->iif))
                goto out;

        if ((rule->mark ^ fl->mark) & rule->mark_mask)
                goto out;

        ret = ops->match(rule, fl, flags);
out:
        return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
}

int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
                     int flags, struct fib_lookup_arg *arg)
{
        struct fib_rule *rule;
        int err;

        rcu_read_lock();

        list_for_each_entry_rcu(rule, &ops->rules_list, list) {
jumped:
                if (!fib_rule_match(rule, ops, fl, flags))
                        continue;

                if (rule->action == FR_ACT_GOTO) {
                        struct fib_rule *target;

                        target = rcu_dereference(rule->ctarget);
                        if (target == NULL) {
                                continue;
                        } else {
                                rule = target;
                                goto jumped;
                        }
                } else if (rule->action == FR_ACT_NOP)
                        continue;
                else
                        err = ops->action(rule, fl, flags, arg);

                if (err != -EAGAIN) {
                        fib_rule_get(rule);
                        arg->rule = rule;
                        goto out;
                }
        }

        err = -ESRCH;
out:
        rcu_read_unlock();

        return err;
}

EXPORT_SYMBOL_GPL(fib_rules_lookup);

static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
                            struct fib_rules_ops *ops)
{
        int err = -EINVAL;

        if (frh->src_len)
                if (tb[FRA_SRC] == NULL ||
                    frh->src_len > (ops->addr_size * 8) ||
                    nla_len(tb[FRA_SRC]) != ops->addr_size)
                        goto errout;

        if (frh->dst_len)
                if (tb[FRA_DST] == NULL ||
                    frh->dst_len > (ops->addr_size * 8) ||
                    nla_len(tb[FRA_DST]) != ops->addr_size)
                        goto errout;

        err = 0;
errout:
        return err;
}

static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
        struct net *net = sock_net(skb->sk);
        struct fib_rule_hdr *frh = nlmsg_data(nlh);
        struct fib_rules_ops *ops = NULL;
        struct fib_rule *rule, *r, *last = NULL;
        struct nlattr *tb[FRA_MAX+1];
        int err = -EINVAL, unresolved = 0;

        if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
                goto errout;

        ops = lookup_rules_ops(net, frh->family);
        if (ops == NULL) {
                err = -EAFNOSUPPORT;
                goto errout;
        }

        err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
        if (err < 0)
                goto errout;

        err = validate_rulemsg(frh, tb, ops);
        if (err < 0)
                goto errout;

        rule = kzalloc(ops->rule_size, GFP_KERNEL);
        if (rule == NULL) {
                err = -ENOMEM;
                goto errout;
        }
        rule->fr_net = hold_net(net);

        if (tb[FRA_PRIORITY])
                rule->pref = nla_get_u32(tb[FRA_PRIORITY]);

        if (tb[FRA_IFNAME]) {
                struct net_device *dev;

                rule->ifindex = -1;
                nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
                dev = __dev_get_by_name(net, rule->ifname);
                if (dev)
                        rule->ifindex = dev->ifindex;
        }

        if (tb[FRA_FWMARK]) {
                rule->mark = nla_get_u32(tb[FRA_FWMARK]);
                if (rule->mark)
                        /* compatibility: if the mark value is non-zero all bits
                         * are compared unless a mask is explicitly specified.
                         */
                        rule->mark_mask = 0xFFFFFFFF;
        }

        if (tb[FRA_FWMASK])
                rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);

        rule->action = frh->action;
        rule->flags = frh->flags;
        rule->table = frh_get_table(frh, tb);

        if (!rule->pref && ops->default_pref)
                rule->pref = ops->default_pref(ops);

        err = -EINVAL;
        if (tb[FRA_GOTO]) {
                if (rule->action != FR_ACT_GOTO)
                        goto errout_free;

                rule->target = nla_get_u32(tb[FRA_GOTO]);
                /* Backward jumps are prohibited to avoid endless loops */
                if (rule->target <= rule->pref)
                        goto errout_free;

                list_for_each_entry(r, &ops->rules_list, list) {
                        if (r->pref == rule->target) {
                                rule->ctarget = r;
                                break;
                        }
                }

                if (rule->ctarget == NULL)
                        unresolved = 1;
        } else if (rule->action == FR_ACT_GOTO)
                goto errout_free;

        err = ops->configure(rule, skb, nlh, frh, tb);
        if (err < 0)
                goto errout_free;

        list_for_each_entry(r, &ops->rules_list, list) {
                if (r->pref > rule->pref)
                        break;
                last = r;
        }

        fib_rule_get(rule);

        if (ops->unresolved_rules) {
                /*
                 * There are unresolved goto rules in the list, check if
                 * any of them are pointing to this new rule.
                 */
                list_for_each_entry(r, &ops->rules_list, list) {
                        if (r->action == FR_ACT_GOTO &&
                            r->target == rule->pref) {
                                BUG_ON(r->ctarget != NULL);
                                rcu_assign_pointer(r->ctarget, rule);
                                if (--ops->unresolved_rules == 0)
                                        break;
                        }
                }
        }

        if (rule->action == FR_ACT_GOTO)
                ops->nr_goto_rules++;

        if (unresolved)
                ops->unresolved_rules++;

        if (last)
                list_add_rcu(&rule->list, &last->list);
        else
                list_add_rcu(&rule->list, &ops->rules_list);

        notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
        flush_route_cache(ops);
        rules_ops_put(ops);
        return 0;

errout_free:
        release_net(rule->fr_net);
        kfree(rule);
errout:
        rules_ops_put(ops);
        return err;
}

static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
{
        struct net *net = sock_net(skb->sk);
        struct fib_rule_hdr *frh = nlmsg_data(nlh);
        struct fib_rules_ops *ops = NULL;
        struct fib_rule *rule, *tmp;
        struct nlattr *tb[FRA_MAX+1];
        int err = -EINVAL;

        if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
                goto errout;

        ops = lookup_rules_ops(net, frh->family);
        if (ops == NULL) {
                err = -EAFNOSUPPORT;
                goto errout;
        }

        err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
        if (err < 0)
                goto errout;

        err = validate_rulemsg(frh, tb, ops);
        if (err < 0)
                goto errout;

        list_for_each_entry(rule, &ops->rules_list, list) {
                if (frh->action && (frh->action != rule->action))
                        continue;

                if (frh->table && (frh_get_table(frh, tb) != rule->table))
                        continue;

                if (tb[FRA_PRIORITY] &&
                    (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
                        continue;

                if (tb[FRA_IFNAME] &&
                    nla_strcmp(tb[FRA_IFNAME], rule->ifname))
                        continue;

                if (tb[FRA_FWMARK] &&
                    (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
                        continue;

                if (tb[FRA_FWMASK] &&
                    (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
                        continue;

                if (!ops->compare(rule, frh, tb))
                        continue;

                if (rule->flags & FIB_RULE_PERMANENT) {
                        err = -EPERM;
                        goto errout;
                }

                list_del_rcu(&rule->list);

                if (rule->action == FR_ACT_GOTO)
                        ops->nr_goto_rules--;

                /*
                 * Check if this rule is a target to any of them. If so,
                 * disable them. As this operation is eventually very
                 * expensive, it is only performed if goto rules have
                 * actually been added.
                 */
                if (ops->nr_goto_rules > 0) {
                        list_for_each_entry(tmp, &ops->rules_list, list) {
                                if (tmp->ctarget == rule) {
                                        rcu_assign_pointer(tmp->ctarget, NULL);
                                        ops->unresolved_rules++;
                                }
                        }
                }

                synchronize_rcu();
                notify_rule_change(RTM_DELRULE, rule, ops, nlh,
                                   NETLINK_CB(skb).pid);
                fib_rule_put(rule);
                flush_route_cache(ops);
                rules_ops_put(ops);
                return 0;
        }

        err = -ENOENT;
errout:
        rules_ops_put(ops);
        return err;
}

static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
                                         struct fib_rule *rule)
{
        size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
                         + nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
                         + nla_total_size(4) /* FRA_PRIORITY */
                         + nla_total_size(4) /* FRA_TABLE */
                         + nla_total_size(4) /* FRA_FWMARK */
                         + nla_total_size(4); /* FRA_FWMASK */

        if (ops->nlmsg_payload)
                payload += ops->nlmsg_payload(rule);

        return payload;
}

static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
                            u32 pid, u32 seq, int type, int flags,
                            struct fib_rules_ops *ops)
{
        struct nlmsghdr *nlh;
        struct fib_rule_hdr *frh;

        nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
        if (nlh == NULL)
                return -EMSGSIZE;

        frh = nlmsg_data(nlh);
        frh->table = rule->table;
        NLA_PUT_U32(skb, FRA_TABLE, rule->table);
        frh->res1 = 0;
        frh->res2 = 0;
        frh->action = rule->action;
        frh->flags = rule->flags;

        if (rule->action == FR_ACT_GOTO && rule->ctarget == NULL)
                frh->flags |= FIB_RULE_UNRESOLVED;

        if (rule->ifname[0]) {
                NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);

                if (rule->ifindex == -1)
                        frh->flags |= FIB_RULE_DEV_DETACHED;
        }

        if (rule->pref)
                NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);

        if (rule->mark)
                NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);

        if (rule->mark_mask || rule->mark)
                NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);

        if (rule->target)
                NLA_PUT_U32(skb, FRA_GOTO, rule->target);

        if (ops->fill(rule, skb, nlh, frh) < 0)
                goto nla_put_failure;

        return nlmsg_end(skb, nlh);

nla_put_failure:
        nlmsg_cancel(skb, nlh);
        return -EMSGSIZE;
}

static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
                      struct fib_rules_ops *ops)
{
        int idx = 0;
        struct fib_rule *rule;

        list_for_each_entry(rule, &ops->rules_list, list) {
                if (idx < cb->args[1])
                        goto skip;

                if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
                                     cb->nlh->nlmsg_seq, RTM_NEWRULE,
                                     NLM_F_MULTI, ops) < 0)
                        break;
skip:
                idx++;
        }
        cb->args[1] = idx;
        rules_ops_put(ops);

        return skb->len;
}

static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct net *net = sock_net(skb->sk);
        struct fib_rules_ops *ops;
        int idx = 0, family;

        family = rtnl_msg_family(cb->nlh);
        if (family != AF_UNSPEC) {
                /* Protocol specific dump request */
                ops = lookup_rules_ops(net, family);
                if (ops == NULL)
                        return -EAFNOSUPPORT;

                return dump_rules(skb, cb, ops);
        }

        rcu_read_lock();
        list_for_each_entry_rcu(ops, &net->rules_ops, list) {
                if (idx < cb->args[0] || !try_module_get(ops->owner))
                        goto skip;

                if (dump_rules(skb, cb, ops) < 0)
                        break;

                cb->args[1] = 0;
        skip:
                idx++;
        }
        rcu_read_unlock();
        cb->args[0] = idx;

        return skb->len;
}

static void notify_rule_change(int event, struct fib_rule *rule,
                               struct fib_rules_ops *ops, struct nlmsghdr *nlh,
                               u32 pid)
{
        struct net *net;
        struct sk_buff *skb;
        int err = -ENOBUFS;

        net = ops->fro_net;
        skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
        if (skb == NULL)
                goto errout;

        err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
        if (err < 0) {
                /* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
                WARN_ON(err == -EMSGSIZE);
                kfree_skb(skb);
                goto errout;
        }

        err = rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
errout:
        if (err < 0)
                rtnl_set_sk_err(net, ops->nlgroup, err);
}

static void attach_rules(struct list_head *rules, struct net_device *dev)
{
        struct fib_rule *rule;

        list_for_each_entry(rule, rules, list) {
                if (rule->ifindex == -1 &&
                    strcmp(dev->name, rule->ifname) == 0)
                        rule->ifindex = dev->ifindex;
        }
}

static void detach_rules(struct list_head *rules, struct net_device *dev)
{
        struct fib_rule *rule;

        list_for_each_entry(rule, rules, list)
                if (rule->ifindex == dev->ifindex)
                        rule->ifindex = -1;
}


static int fib_rules_event(struct notifier_block *this, unsigned long event,
                            void *ptr)
{
        struct net_device *dev = ptr;
        struct net *net = dev_net(dev);
        struct fib_rules_ops *ops;

        ASSERT_RTNL();
        rcu_read_lock();

        switch (event) {
        case NETDEV_REGISTER:
                list_for_each_entry(ops, &net->rules_ops, list)
                        attach_rules(&ops->rules_list, dev);
                break;

        case NETDEV_UNREGISTER:
                list_for_each_entry(ops, &net->rules_ops, list)
                        detach_rules(&ops->rules_list, dev);
                break;
        }

        rcu_read_unlock();

        return NOTIFY_DONE;
}

static struct notifier_block fib_rules_notifier = {
        .notifier_call = fib_rules_event,
};

static int fib_rules_net_init(struct net *net)
{
        INIT_LIST_HEAD(&net->rules_ops);
        spin_lock_init(&net->rules_mod_lock);
        return 0;
}

static struct pernet_operations fib_rules_net_ops = {
        .init = fib_rules_net_init,
};

static int __init fib_rules_init(void)
{
        int err;
        rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
        rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
        rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);

        err = register_netdevice_notifier(&fib_rules_notifier);
        if (err < 0)
                goto fail;

        err = register_pernet_subsys(&fib_rules_net_ops);
        if (err < 0)
                goto fail_unregister;
        return 0;

fail_unregister:
        unregister_netdevice_notifier(&fib_rules_notifier);
fail:
        rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
        rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
        rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
        return err;
}

subsys_initcall(fib_rules_init);

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