Commit 6133740d authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso

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\; }
 <cmdline>: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: default avatarPablo Neira Ayuso <>
parent 508f8ccd
......@@ -1348,6 +1348,37 @@ static int nf_tables_newchain(struct net *net, struct sock *nlsk,
if (nlh->nlmsg_flags & NLM_F_REPLACE)
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,
if (err < 0)
return err;
basechain = nft_base_chain(chain);
if (basechain->type != hook.type) {
return -EBUSY;
for (i = 0; i < afi->nops; i++) {
ops = &basechain->ops[i];
if (ops->hooknum != hook.num ||
ops->priority != hook.priority ||
ops->dev != {
return -EBUSY;
if (nla[NFTA_CHAIN_HANDLE] && name) {
struct nft_chain *chain2;
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