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netfilter: nf_tables: fix module unload race 

We must first remove the nfnetlink protocol handler when nf_tables module
is unloaded -- we don't want userspace to submit new change requests once
we've started to tear down nft state.

Furthermore, nfnetlink must not call any subsystem function after
call_batch returned -EAGAIN.

EAGAIN means the subsys mutex was dropped, so its unlikely but possible that
nf_tables subsystem was removed due to 'rmmod nf_tables' on another cpu.

Therefore, we must abort batch completely and not move on to next part of
the batch.

Last, we can't invoke ->abort unless we've checked that the subsystem is
still registered.

Change netns exit path of nf_tables to make sure any incompleted
transaction gets removed on exit.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
hifive-unleashed-5.1
Florian Westphal 2018-06-11 13:20:35 +02:00 committed by Pablo Neira Ayuso
parent 215a31f19d
commit 71ad00c50d
2 changed files with 16 additions and 6 deletions
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12
net/netfilter/nf_tables_api.c
View File

@ -6439,7 +6439,7 @@ static void nf_tables_abort_release(struct nft_trans *trans)
kfree(trans);
}
static int nf_tables_abort(struct net *net, struct sk_buff *skb)
static int __nf_tables_abort(struct net *net)
{
struct nft_trans *trans, *next;
struct nft_trans_elem *te;
@ -6555,6 +6555,11 @@ static void nf_tables_cleanup(struct net *net)
nft_validate_state_update(net, NFT_VALIDATE_SKIP);
}
static int nf_tables_abort(struct net *net, struct sk_buff *skb)
{
return __nf_tables_abort(net);
}
static bool nf_tables_valid_genid(struct net *net, u32 genid)
{
return net->nft.base_seq == genid;
@ -7149,9 +7154,10 @@ static int __net_init nf_tables_init_net(struct net *net)
static void __net_exit nf_tables_exit_net(struct net *net)
{
if (!list_empty(&net->nft.commit_list))
__nf_tables_abort(net);
__nft_release_tables(net);
WARN_ON_ONCE(!list_empty(&net->nft.tables));
WARN_ON_ONCE(!list_empty(&net->nft.commit_list));
}
static struct pernet_operations nf_tables_net_ops = {
@ -7193,9 +7199,9 @@ err1:
static void __exit nf_tables_module_exit(void)
{
unregister_pernet_subsys(&nf_tables_net_ops);
nfnetlink_subsys_unregister(&nf_tables_subsys);
unregister_netdevice_notifier(&nf_tables_flowtable_notifier);
unregister_pernet_subsys(&nf_tables_net_ops);
rcu_barrier();
nf_tables_core_module_exit();
kfree(info);

10
net/netfilter/nfnetlink.c
View File

@ -429,7 +429,7 @@ replay:
*/
if (err == -EAGAIN) {
status |= NFNL_BATCH_REPLAY;
goto next;
goto done;
}
}
ack:
@ -456,7 +456,7 @@ ack:
if (err)
status |= NFNL_BATCH_FAILURE;
}
next:
msglen = NLMSG_ALIGN(nlh->nlmsg_len);
if (msglen > skb->len)
msglen = skb->len;
@ -464,7 +464,11 @@ next:
}
done:
if (status & NFNL_BATCH_REPLAY) {
ss->abort(net, oskb);
const struct nfnetlink_subsystem *ss2;
ss2 = nfnl_dereference_protected(subsys_id);
if (ss2 == ss)
ss->abort(net, oskb);
nfnl_err_reset(&err_list);
nfnl_unlock(subsys_id);
kfree_skb(skb);