forked from luck/tmp_suning_uos_patched
864150dfa3
When a listener registers to the FIB notification chain it receives a
dump of the FIB entries and rules from existing address families by
invoking their dump operations.
While we call into these modules we need to make sure they aren't
removed. Do that by increasing their reference count before invoking
their dump operations and decrease it afterwards.
Fixes: 04b1d4e50e
("net: core: Make the FIB notification chain generic")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
174 lines
3.7 KiB
C
174 lines
3.7 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 <linux/module.h>
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#include <linux/init.h>
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#include <net/net_namespace.h>
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#include <net/fib_notifier.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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EXPORT_SYMBOL(call_fib_notifier);
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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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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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EXPORT_SYMBOL(call_fib_notifiers);
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static unsigned int fib_seq_sum(void)
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{
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struct fib_notifier_ops *ops;
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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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list_for_each_entry(ops, &net->fib_notifier_ops, list) {
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if (!try_module_get(ops->owner))
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continue;
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fib_seq += ops->fib_seq_read(net);
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module_put(ops->owner);
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}
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}
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rtnl_unlock();
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return fib_seq;
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}
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static int fib_net_dump(struct net *net, struct notifier_block *nb)
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{
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struct fib_notifier_ops *ops;
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list_for_each_entry_rcu(ops, &net->fib_notifier_ops, list) {
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int err;
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if (!try_module_get(ops->owner))
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continue;
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err = ops->fib_dump(net, nb);
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module_put(ops->owner);
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if (err)
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return err;
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}
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return 0;
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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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int err;
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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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rcu_read_lock();
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for_each_net_rcu(net) {
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err = fib_net_dump(net, nb);
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if (err)
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goto err_fib_net_dump;
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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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err_fib_net_dump:
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rcu_read_unlock();
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return err;
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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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static int __fib_notifier_ops_register(struct fib_notifier_ops *ops,
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struct net *net)
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{
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struct fib_notifier_ops *o;
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list_for_each_entry(o, &net->fib_notifier_ops, list)
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if (ops->family == o->family)
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return -EEXIST;
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list_add_tail_rcu(&ops->list, &net->fib_notifier_ops);
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return 0;
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}
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struct fib_notifier_ops *
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fib_notifier_ops_register(const struct fib_notifier_ops *tmpl, struct net *net)
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{
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struct fib_notifier_ops *ops;
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int err;
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ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
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if (!ops)
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return ERR_PTR(-ENOMEM);
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err = __fib_notifier_ops_register(ops, net);
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if (err)
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goto err_register;
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return ops;
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err_register:
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kfree(ops);
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return ERR_PTR(err);
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}
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EXPORT_SYMBOL(fib_notifier_ops_register);
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void fib_notifier_ops_unregister(struct fib_notifier_ops *ops)
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{
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list_del_rcu(&ops->list);
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kfree_rcu(ops, rcu);
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}
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EXPORT_SYMBOL(fib_notifier_ops_unregister);
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static int __net_init fib_notifier_net_init(struct net *net)
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{
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INIT_LIST_HEAD(&net->fib_notifier_ops);
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return 0;
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}
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static struct pernet_operations fib_notifier_net_ops = {
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.init = fib_notifier_net_init,
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};
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static int __init fib_notifier_init(void)
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{
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return register_pernet_subsys(&fib_notifier_net_ops);
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}
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subsys_initcall(fib_notifier_init);
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