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netfilter: nf_tables: fix addition/deletion of elements from commit/abort 

We have several problems in this path:

1) There is a use-after-free when removing individual elements from
   the commit path.

2) We have to uninit() the data part of the element from the abort
   path to avoid a chain refcount leak.

3) We have to check for set->flags to see if there's a mapping, instead
   of the element flags.

4) We have to check for !(flags & NFT_SET_ELEM_INTERVAL_END) to skip
   elements that are part of the interval that have no data part, so
   they don't need to be uninit().

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2015-02-20 17:11:10 +01:00
parent 2156d321b8
commit 02263db00b
1 changed files with 12 additions and 9 deletions
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21
net/netfilter/nf_tables_api.c
View File

@ -3612,12 +3612,11 @@ static int nf_tables_commit(struct sk_buff *skb)
&te->elem,
NFT_MSG_DELSETELEM, 0);
te->set->ops->get(te->set, &te->elem);
te->set->ops->remove(te->set, &te->elem);
nft_data_uninit(&te->elem.key, NFT_DATA_VALUE);
if (te->elem.flags & NFT_SET_MAP) {
nft_data_uninit(&te->elem.data,
te->set->dtype);
}
if (te->set->flags & NFT_SET_MAP &&
!(te->elem.flags & NFT_SET_ELEM_INTERVAL_END))
nft_data_uninit(&te->elem.data, te->set->dtype);
te->set->ops->remove(te->set, &te->elem);
nft_trans_destroy(trans);
break;
}
@ -3658,7 +3657,7 @@ static int nf_tables_abort(struct sk_buff *skb)
{
struct net *net = sock_net(skb->sk);
struct nft_trans *trans, *next;
struct nft_set *set;
struct nft_trans_elem *te;
list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) {
switch (trans->msg_type) {
@ -3719,9 +3718,13 @@ static int nf_tables_abort(struct sk_buff *skb)
break;
case NFT_MSG_NEWSETELEM:
nft_trans_elem_set(trans)->nelems--;
set = nft_trans_elem_set(trans);
set->ops->get(set, &nft_trans_elem(trans));
set->ops->remove(set, &nft_trans_elem(trans));
te = (struct nft_trans_elem *)trans->data;
te->set->ops->get(te->set, &te->elem);
nft_data_uninit(&te->elem.key, NFT_DATA_VALUE);
if (te->set->flags & NFT_SET_MAP &&
!(te->elem.flags & NFT_SET_ELEM_INTERVAL_END))
nft_data_uninit(&te->elem.data, te->set->dtype);
te->set->ops->remove(te->set, &te->elem);
nft_trans_destroy(trans);
break;
case NFT_MSG_DELSETELEM: