Currently netlink users BUG when the allocated skb for an event notification is undersized. While this is certainly a kernel bug, its not critical and crashing the kernel is too drastic, especially when considering that these errors have appeared multiple times in the past and it BUGs even if no listeners are present. This patch replaces BUG by WARN_ON and changes the notification functions to inform potential listeners of undersized allocations using a unique error code (EMSGSIZE). Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
477 lines
9.9 KiB
C
477 lines
9.9 KiB
C
/*
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* net/core/fib_rules.c Generic Routing Rules
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2.
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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*/
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/list.h>
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#include <net/fib_rules.h>
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static LIST_HEAD(rules_ops);
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static DEFINE_SPINLOCK(rules_mod_lock);
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static void notify_rule_change(int event, struct fib_rule *rule,
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struct fib_rules_ops *ops, struct nlmsghdr *nlh,
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u32 pid);
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static struct fib_rules_ops *lookup_rules_ops(int family)
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{
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struct fib_rules_ops *ops;
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rcu_read_lock();
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list_for_each_entry_rcu(ops, &rules_ops, list) {
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if (ops->family == family) {
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if (!try_module_get(ops->owner))
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ops = NULL;
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rcu_read_unlock();
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return ops;
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}
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}
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rcu_read_unlock();
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return NULL;
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}
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static void rules_ops_put(struct fib_rules_ops *ops)
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{
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if (ops)
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module_put(ops->owner);
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}
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int fib_rules_register(struct fib_rules_ops *ops)
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{
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int err = -EEXIST;
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struct fib_rules_ops *o;
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if (ops->rule_size < sizeof(struct fib_rule))
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return -EINVAL;
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if (ops->match == NULL || ops->configure == NULL ||
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ops->compare == NULL || ops->fill == NULL ||
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ops->action == NULL)
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return -EINVAL;
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spin_lock(&rules_mod_lock);
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list_for_each_entry(o, &rules_ops, list)
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if (ops->family == o->family)
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goto errout;
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list_add_tail_rcu(&ops->list, &rules_ops);
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err = 0;
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errout:
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spin_unlock(&rules_mod_lock);
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return err;
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}
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EXPORT_SYMBOL_GPL(fib_rules_register);
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static void cleanup_ops(struct fib_rules_ops *ops)
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{
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struct fib_rule *rule, *tmp;
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list_for_each_entry_safe(rule, tmp, ops->rules_list, list) {
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list_del_rcu(&rule->list);
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fib_rule_put(rule);
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}
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}
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int fib_rules_unregister(struct fib_rules_ops *ops)
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{
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int err = 0;
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struct fib_rules_ops *o;
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spin_lock(&rules_mod_lock);
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list_for_each_entry(o, &rules_ops, list) {
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if (o == ops) {
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list_del_rcu(&o->list);
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cleanup_ops(ops);
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goto out;
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}
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}
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err = -ENOENT;
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out:
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spin_unlock(&rules_mod_lock);
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synchronize_rcu();
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return err;
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}
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EXPORT_SYMBOL_GPL(fib_rules_unregister);
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static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
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struct flowi *fl, int flags)
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{
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int ret = 0;
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if (rule->ifindex && (rule->ifindex != fl->iif))
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goto out;
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if ((rule->mark ^ fl->mark) & rule->mark_mask)
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goto out;
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ret = ops->match(rule, fl, flags);
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out:
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return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
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}
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int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
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int flags, struct fib_lookup_arg *arg)
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{
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struct fib_rule *rule;
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int err;
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rcu_read_lock();
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list_for_each_entry_rcu(rule, ops->rules_list, list) {
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if (!fib_rule_match(rule, ops, fl, flags))
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continue;
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err = ops->action(rule, fl, flags, arg);
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if (err != -EAGAIN) {
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fib_rule_get(rule);
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arg->rule = rule;
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goto out;
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}
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}
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err = -ENETUNREACH;
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out:
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rcu_read_unlock();
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return err;
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}
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EXPORT_SYMBOL_GPL(fib_rules_lookup);
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int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
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{
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struct fib_rule_hdr *frh = nlmsg_data(nlh);
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struct fib_rules_ops *ops = NULL;
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struct fib_rule *rule, *r, *last = NULL;
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struct nlattr *tb[FRA_MAX+1];
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int err = -EINVAL;
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if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
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goto errout;
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ops = lookup_rules_ops(frh->family);
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if (ops == NULL) {
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err = EAFNOSUPPORT;
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goto errout;
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}
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err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
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if (err < 0)
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goto errout;
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rule = kzalloc(ops->rule_size, GFP_KERNEL);
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if (rule == NULL) {
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err = -ENOMEM;
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goto errout;
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}
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if (tb[FRA_PRIORITY])
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rule->pref = nla_get_u32(tb[FRA_PRIORITY]);
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if (tb[FRA_IFNAME]) {
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struct net_device *dev;
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rule->ifindex = -1;
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nla_strlcpy(rule->ifname, tb[FRA_IFNAME], IFNAMSIZ);
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dev = __dev_get_by_name(rule->ifname);
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if (dev)
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rule->ifindex = dev->ifindex;
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}
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if (tb[FRA_FWMARK]) {
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rule->mark = nla_get_u32(tb[FRA_FWMARK]);
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if (rule->mark)
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/* compatibility: if the mark value is non-zero all bits
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* are compared unless a mask is explicitly specified.
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*/
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rule->mark_mask = 0xFFFFFFFF;
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}
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if (tb[FRA_FWMASK])
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rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);
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rule->action = frh->action;
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rule->flags = frh->flags;
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rule->table = frh_get_table(frh, tb);
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if (!rule->pref && ops->default_pref)
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rule->pref = ops->default_pref();
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err = ops->configure(rule, skb, nlh, frh, tb);
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if (err < 0)
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goto errout_free;
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list_for_each_entry(r, ops->rules_list, list) {
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if (r->pref > rule->pref)
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break;
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last = r;
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}
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fib_rule_get(rule);
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if (last)
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list_add_rcu(&rule->list, &last->list);
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else
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list_add_rcu(&rule->list, ops->rules_list);
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notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
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rules_ops_put(ops);
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return 0;
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errout_free:
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kfree(rule);
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errout:
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rules_ops_put(ops);
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return err;
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}
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int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
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{
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struct fib_rule_hdr *frh = nlmsg_data(nlh);
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struct fib_rules_ops *ops = NULL;
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struct fib_rule *rule;
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struct nlattr *tb[FRA_MAX+1];
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int err = -EINVAL;
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if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
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goto errout;
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ops = lookup_rules_ops(frh->family);
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if (ops == NULL) {
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err = EAFNOSUPPORT;
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goto errout;
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}
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err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
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if (err < 0)
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goto errout;
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list_for_each_entry(rule, ops->rules_list, list) {
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if (frh->action && (frh->action != rule->action))
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continue;
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if (frh->table && (frh_get_table(frh, tb) != rule->table))
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continue;
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if (tb[FRA_PRIORITY] &&
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(rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
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continue;
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if (tb[FRA_IFNAME] &&
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nla_strcmp(tb[FRA_IFNAME], rule->ifname))
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continue;
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if (tb[FRA_FWMARK] &&
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(rule->mark != nla_get_u32(tb[FRA_FWMARK])))
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continue;
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if (tb[FRA_FWMASK] &&
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(rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
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continue;
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if (!ops->compare(rule, frh, tb))
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continue;
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if (rule->flags & FIB_RULE_PERMANENT) {
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err = -EPERM;
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goto errout;
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}
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list_del_rcu(&rule->list);
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synchronize_rcu();
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notify_rule_change(RTM_DELRULE, rule, ops, nlh,
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NETLINK_CB(skb).pid);
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fib_rule_put(rule);
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rules_ops_put(ops);
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return 0;
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}
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err = -ENOENT;
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errout:
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rules_ops_put(ops);
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return err;
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}
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static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
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struct fib_rule *rule)
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{
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size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
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+ nla_total_size(IFNAMSIZ) /* FRA_IFNAME */
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+ nla_total_size(4) /* FRA_PRIORITY */
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+ nla_total_size(4) /* FRA_TABLE */
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+ nla_total_size(4) /* FRA_FWMARK */
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+ nla_total_size(4); /* FRA_FWMASK */
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if (ops->nlmsg_payload)
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payload += ops->nlmsg_payload(rule);
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return payload;
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}
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static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
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u32 pid, u32 seq, int type, int flags,
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struct fib_rules_ops *ops)
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{
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struct nlmsghdr *nlh;
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struct fib_rule_hdr *frh;
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nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
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if (nlh == NULL)
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return -EMSGSIZE;
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frh = nlmsg_data(nlh);
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frh->table = rule->table;
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NLA_PUT_U32(skb, FRA_TABLE, rule->table);
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frh->res1 = 0;
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frh->res2 = 0;
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frh->action = rule->action;
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frh->flags = rule->flags;
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if (rule->ifname[0])
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NLA_PUT_STRING(skb, FRA_IFNAME, rule->ifname);
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if (rule->pref)
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NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);
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if (rule->mark)
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NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);
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if (rule->mark_mask || rule->mark)
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NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);
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if (ops->fill(rule, skb, nlh, frh) < 0)
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goto nla_put_failure;
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return nlmsg_end(skb, nlh);
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nla_put_failure:
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nlmsg_cancel(skb, nlh);
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return -EMSGSIZE;
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}
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int fib_rules_dump(struct sk_buff *skb, struct netlink_callback *cb, int family)
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{
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int idx = 0;
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struct fib_rule *rule;
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struct fib_rules_ops *ops;
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ops = lookup_rules_ops(family);
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if (ops == NULL)
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return -EAFNOSUPPORT;
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rcu_read_lock();
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list_for_each_entry(rule, ops->rules_list, list) {
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if (idx < cb->args[0])
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goto skip;
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if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
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cb->nlh->nlmsg_seq, RTM_NEWRULE,
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NLM_F_MULTI, ops) < 0)
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break;
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skip:
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idx++;
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}
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rcu_read_unlock();
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cb->args[0] = idx;
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rules_ops_put(ops);
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return skb->len;
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}
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EXPORT_SYMBOL_GPL(fib_rules_dump);
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static void notify_rule_change(int event, struct fib_rule *rule,
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struct fib_rules_ops *ops, struct nlmsghdr *nlh,
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u32 pid)
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{
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struct sk_buff *skb;
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int err = -ENOBUFS;
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skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
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if (skb == NULL)
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goto errout;
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err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
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if (err < 0) {
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/* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
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WARN_ON(err == -EMSGSIZE);
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kfree_skb(skb);
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goto errout;
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}
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err = rtnl_notify(skb, pid, ops->nlgroup, nlh, GFP_KERNEL);
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errout:
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if (err < 0)
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rtnl_set_sk_err(ops->nlgroup, err);
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}
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static void attach_rules(struct list_head *rules, struct net_device *dev)
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{
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struct fib_rule *rule;
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list_for_each_entry(rule, rules, list) {
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if (rule->ifindex == -1 &&
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strcmp(dev->name, rule->ifname) == 0)
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rule->ifindex = dev->ifindex;
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}
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}
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static void detach_rules(struct list_head *rules, struct net_device *dev)
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{
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struct fib_rule *rule;
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list_for_each_entry(rule, rules, list)
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if (rule->ifindex == dev->ifindex)
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rule->ifindex = -1;
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}
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static int fib_rules_event(struct notifier_block *this, unsigned long event,
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void *ptr)
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{
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struct net_device *dev = ptr;
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struct fib_rules_ops *ops;
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ASSERT_RTNL();
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rcu_read_lock();
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switch (event) {
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case NETDEV_REGISTER:
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list_for_each_entry(ops, &rules_ops, list)
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attach_rules(ops->rules_list, dev);
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break;
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case NETDEV_UNREGISTER:
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list_for_each_entry(ops, &rules_ops, list)
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detach_rules(ops->rules_list, dev);
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break;
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}
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rcu_read_unlock();
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return NOTIFY_DONE;
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}
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static struct notifier_block fib_rules_notifier = {
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.notifier_call = fib_rules_event,
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};
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static int __init fib_rules_init(void)
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{
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return register_netdevice_notifier(&fib_rules_notifier);
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}
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subsys_initcall(fib_rules_init);
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