diff options
| -rw-r--r-- | net/netfilter/nf_tables_api.c | 64 |
1 files changed, 63 insertions, 1 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 36f69acaf51f..cc8ca00e6e6e 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -74,15 +74,77 @@ static void nft_trans_destroy(struct nft_trans *trans) kfree(trans); } +/* removal requests are queued in the commit_list, but not acted upon + * until after all new rules are in place. + * + * Therefore, nf_register_net_hook(net, &nat_hook) runs before pending + * nf_unregister_net_hook(). + * + * nf_register_net_hook thus fails if a nat hook is already in place + * even if the conflicting hook is about to be removed. + * + * If collision is detected, search commit_log for DELCHAIN matching + * the new nat hooknum; if we find one collision is temporary: + * + * Either transaction is aborted (new/colliding hook is removed), or + * transaction is committed (old hook is removed). + */ +static bool nf_tables_allow_nat_conflict(const struct net *net, + const struct nf_hook_ops *ops) +{ + const struct nft_trans *trans; + bool ret = false; + + if (!ops->nat_hook) + return false; + + list_for_each_entry(trans, &net->nft.commit_list, list) { + const struct nf_hook_ops *pending_ops; + const struct nft_chain *pending; + + if (trans->msg_type != NFT_MSG_NEWCHAIN && + trans->msg_type != NFT_MSG_DELCHAIN) + continue; + + pending = trans->ctx.chain; + if (!nft_is_base_chain(pending)) + continue; + + pending_ops = &nft_base_chain(pending)->ops; + if (pending_ops->nat_hook && + pending_ops->pf == ops->pf && + pending_ops->hooknum == ops->hooknum) { + /* other hook registration already pending? */ + if (trans->msg_type == NFT_MSG_NEWCHAIN) + return false; + + ret = true; + } + } + + return ret; +} + static int nf_tables_register_hook(struct net *net, const struct nft_table *table, struct nft_chain *chain) { + struct nf_hook_ops *ops; + int ret; + if (table->flags & NFT_TABLE_F_DORMANT || !nft_is_base_chain(chain)) return 0; - return nf_register_net_hook(net, &nft_base_chain(chain)->ops); + ops = &nft_base_chain(chain)->ops; + ret = nf_register_net_hook(net, ops); + if (ret == -EBUSY && nf_tables_allow_nat_conflict(net, ops)) { + ops->nat_hook = false; + ret = nf_register_net_hook(net, ops); + ops->nat_hook = true; + } + + return ret; } static void nf_tables_unregister_hook(struct net *net, |