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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: 5e94846686 ("netfilter: nf_tables: add insert operation")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Florian Westphal 2018-11-04 12:07:14 +01:00 committed by Pablo Neira Ayuso
parent 25d8bcedbf
commit 447750f281
1 changed files with 7 additions and 10 deletions
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17
net/netfilter/nf_tables_api.c
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@ -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);
}
}
}