From caf2a3cbbce4749832dc67b106a6510dbb0c1dbc Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Thu, 14 Feb 2019 10:16:48 +0800 Subject: [PATCH] netfilter: nf_tables: don't use position attribute on rule replacement mainline inclusion from mainline-4.20 commit 447750f281ab category: bugfix bugzilla: 6114 CVE: NA ------------------------------------------------- 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 Signed-off-by: Keefe LIU Reviewed-by: Wei Yongjun Signed-off-by: Yang Yingliang --- 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 38654730230b..3c75b970366e 100644 --- a/net/netfilter/nf_tables_api.c +++ b/net/netfilter/nf_tables_api.c @@ -2570,17 +2570,14 @@ 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); + } } } -- GitLab