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Subject[PATCH 4.14 030/165] netfilter: nf_tables: dont allow to rename to already-pending name
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Westphal <fw@strlen.de>

[ Upstream commit c6cc94df65c3174be92afbee638f11cbb5e606a7 ]

Its possible to rename two chains to the same name in one
transaction:

nft add chain t c1
nft add chain t c2
nft 'rename chain t c1 c3;rename chain t c2 c3'

This creates two chains named 'c3'.

Appears to be harmless, both chains can still be deleted both
by name or handle, but, nevertheless, its a bug.

Walk transaction log and also compare vs. the pending renames.

Both chains can still be deleted, but nevertheless it is a bug as
we don't allow to create chains with identical names, so we should
prevent this from happening-by-rename too.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/netfilter/nf_tables_api.c | 42 +++++++++++++++++++++++++++++-------------
1 file changed, 29 insertions(+), 13 deletions(-)

--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -1480,7 +1480,6 @@ static int nf_tables_updchain(struct nft
struct nft_base_chain *basechain;
struct nft_stats *stats = NULL;
struct nft_chain_hook hook;
- const struct nlattr *name;
struct nf_hook_ops *ops;
struct nft_trans *trans;
int err, i;
@@ -1531,12 +1530,11 @@ static int nf_tables_updchain(struct nft
return PTR_ERR(stats);
}

+ err = -ENOMEM;
trans = nft_trans_alloc(ctx, NFT_MSG_NEWCHAIN,
sizeof(struct nft_trans_chain));
- if (trans == NULL) {
- free_percpu(stats);
- return -ENOMEM;
- }
+ if (trans == NULL)
+ goto err;

nft_trans_chain_stats(trans) = stats;
nft_trans_chain_update(trans) = true;
@@ -1546,19 +1544,37 @@ static int nf_tables_updchain(struct nft
else
nft_trans_chain_policy(trans) = -1;

- name = nla[NFTA_CHAIN_NAME];
- if (nla[NFTA_CHAIN_HANDLE] && name) {
- nft_trans_chain_name(trans) =
- nla_strdup(name, GFP_KERNEL);
- if (!nft_trans_chain_name(trans)) {
- kfree(trans);
- free_percpu(stats);
- return -ENOMEM;
+ if (nla[NFTA_CHAIN_HANDLE] &&
+ nla[NFTA_CHAIN_NAME]) {
+ struct nft_trans *tmp;
+ char *name;
+
+ err = -ENOMEM;
+ name = nla_strdup(nla[NFTA_CHAIN_NAME], GFP_KERNEL);
+ if (!name)
+ goto err;
+
+ err = -EEXIST;
+ list_for_each_entry(tmp, &ctx->net->nft.commit_list, list) {
+ if (tmp->msg_type == NFT_MSG_NEWCHAIN &&
+ tmp->ctx.table == table &&
+ nft_trans_chain_update(tmp) &&
+ nft_trans_chain_name(tmp) &&
+ strcmp(name, nft_trans_chain_name(tmp)) == 0) {
+ kfree(name);
+ goto err;
+ }
}
+
+ nft_trans_chain_name(trans) = name;
}
list_add_tail(&trans->list, &ctx->net->nft.commit_list);

return 0;
+err:
+ free_percpu(stats);
+ kfree(trans);
+ return err;
}

static int nf_tables_newchain(struct net *net, struct sock *nlsk,

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