From: Florian Westphal Date: Sun, 4 Nov 2018 11:07:14 +0000 (+0100) Subject: netfilter: nf_tables: don't use position attribute on rule replacement X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=447750f281abef547be44fdcfe3bc4447b3115a8;p=openwrt%2Fstaging%2Fblogic.git netfilter: nf_tables: don't use position attribute on rule replacement Its possible to set both HANDLE and POSITION when replacing a rule. In this case, the rule at POSITION gets replaced using the userspace-provided handle. Rule handles are supposed to be generated by the kernel only. Duplicate handles should be harmless, however better disable this "feature" by only checking for the POSITION attribute on insert operations. Fixes: 5e94846686d0 ("netfilter: nf_tables: add insert operation") Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c index dd577e7d100c..e496030fdc3b 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -2589,17 +2589,14 @@ static int nf_tables_newrule(struct net *net, struct sock *nlsk, if (chain->use == UINT_MAX) return -EOVERFLOW; - } - - if (nla[NFTA_RULE_POSITION]) { - if (!(nlh->nlmsg_flags & NLM_F_CREATE)) - return -EOPNOTSUPP; - pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION])); - old_rule = __nft_rule_lookup(chain, pos_handle); - if (IS_ERR(old_rule)) { - NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]); - return PTR_ERR(old_rule); + if (nla[NFTA_RULE_POSITION]) { + pos_handle = be64_to_cpu(nla_get_be64(nla[NFTA_RULE_POSITION])); + old_rule = __nft_rule_lookup(chain, pos_handle); + if (IS_ERR(old_rule)) { + NL_SET_BAD_ATTR(extack, nla[NFTA_RULE_POSITION]); + return PTR_ERR(old_rule); + } } }