87 lines
1.9 KiB
C
87 lines
1.9 KiB
C
#include <linux/rtnetlink.h>
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#include <linux/notifier.h>
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#include <linux/rcupdate.h>
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#include <linux/kernel.h>
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#include <net/net_namespace.h>
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#include <net/netns/ipv4.h>
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#include <net/ip_fib.h>
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static ATOMIC_NOTIFIER_HEAD(fib_chain);
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int call_fib_notifier(struct notifier_block *nb, struct net *net,
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enum fib_event_type event_type,
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struct fib_notifier_info *info)
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{
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info->net = net;
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return nb->notifier_call(nb, event_type, info);
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}
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int call_fib_notifiers(struct net *net, enum fib_event_type event_type,
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struct fib_notifier_info *info)
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{
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net->ipv4.fib_seq++;
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info->net = net;
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return atomic_notifier_call_chain(&fib_chain, event_type, info);
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}
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static unsigned int fib_seq_sum(void)
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{
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unsigned int fib_seq = 0;
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struct net *net;
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rtnl_lock();
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for_each_net(net)
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fib_seq += net->ipv4.fib_seq;
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rtnl_unlock();
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return fib_seq;
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}
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static bool fib_dump_is_consistent(struct notifier_block *nb,
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void (*cb)(struct notifier_block *nb),
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unsigned int fib_seq)
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{
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atomic_notifier_chain_register(&fib_chain, nb);
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if (fib_seq == fib_seq_sum())
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return true;
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atomic_notifier_chain_unregister(&fib_chain, nb);
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if (cb)
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cb(nb);
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return false;
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}
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#define FIB_DUMP_MAX_RETRIES 5
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int register_fib_notifier(struct notifier_block *nb,
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void (*cb)(struct notifier_block *nb))
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{
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int retries = 0;
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do {
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unsigned int fib_seq = fib_seq_sum();
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struct net *net;
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/* Mutex semantics guarantee that every change done to
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* FIB tries before we read the change sequence counter
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* is now visible to us.
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*/
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rcu_read_lock();
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for_each_net_rcu(net) {
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fib_rules_notify(net, nb);
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fib_notify(net, nb);
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}
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rcu_read_unlock();
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if (fib_dump_is_consistent(nb, cb, fib_seq))
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return 0;
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} while (++retries < FIB_DUMP_MAX_RETRIES);
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return -EBUSY;
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}
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EXPORT_SYMBOL(register_fib_notifier);
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int unregister_fib_notifier(struct notifier_block *nb)
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{
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return atomic_notifier_chain_unregister(&fib_chain, nb);
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}
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EXPORT_SYMBOL(unregister_fib_notifier);
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