From 6133740d6e80d969ff7d41098a9db1091d0f9c94 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Tue, 2 Aug 2016 00:30:38 +0200 Subject: [PATCH] netfilter: nf_tables: reject hook configuration updates on existing chains Currently, if you add a base chain whose name clashes with an existing non-base chain, nf_tables doesn't complain about this. Similarly, if you update the chain type, the hook number and priority. With this patch, nf_tables bails out in case any of this unsupported operations occur by returning EBUSY. # nft add table x # nft add chain x y # nft add chain x y { type nat hook input priority 0\; } :1:1-49: Error: Could not process rule: Device or resource busy add chain x y { type nat hook input priority 0; } ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nf_tables_api.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index 463fcad..221d27f 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -1348,6 +1348,37 @@ static int nf_tables_newchain(struct net *net, struct sock *nlsk, if (nlh->nlmsg_flags & NLM_F_REPLACE) return -EOPNOTSUPP; + if (nla[NFTA_CHAIN_HOOK]) { + struct nft_base_chain *basechain; + struct nft_chain_hook hook; + struct nf_hook_ops *ops; + + if (!(chain->flags & NFT_BASE_CHAIN)) + return -EBUSY; + + err = nft_chain_parse_hook(net, nla, afi, &hook, + create); + if (err < 0) + return err; + + basechain = nft_base_chain(chain); + if (basechain->type != hook.type) { + nft_chain_release_hook(&hook); + return -EBUSY; + } + + for (i = 0; i < afi->nops; i++) { + ops = &basechain->ops[i]; + if (ops->hooknum != hook.num || + ops->priority != hook.priority || + ops->dev != hook.dev) { + nft_chain_release_hook(&hook); + return -EBUSY; + } + } + nft_chain_release_hook(&hook); + } + if (nla[NFTA_CHAIN_HANDLE] && name) { struct nft_chain *chain2; -- 2.7.4