From 447750f281abef547be44fdcfe3bc4447b3115a8 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Sun, 4 Nov 2018 12:07:14 +0100 Subject: [PATCH] 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 --- net/netfilter/nf_tables_api.c | 17 +++++++---------- 1 file changed, 7 insertions(+), 10 deletions(-) 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); + } } } -- 2.45.2