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authorPablo Neira Ayuso <pablo@netfilter.org>2014-11-10 21:14:12 +0100
committerPablo Neira Ayuso <pablo@netfilter.org>2014-11-12 12:06:24 +0100
commitb326dd37b94e29bf6a15940f4fa66aa21a678ab1 (patch)
tree3da47178073b5ef4c15198df0baa1ac7eb66954e /net/netfilter
parentafefb6f928ed42d5db452ee9251ce6de62673c67 (diff)
netfilter: nf_tables: restore synchronous object release from commit/abort
The existing xtables matches and targets, when used from nft_compat, may sleep from the destroy path, ie. when removing rules. Since the objects are released via call_rcu from softirq context, this results in lockdep splats and possible lockups that may be hard to reproduce. Patrick also indicated that delayed object release via call_rcu can cause us problems in the ordering of event notifications when anonymous sets are in place. So, this patch restores the synchronous object release from the commit and abort paths. This includes a call to synchronize_rcu() to make sure that no packets are walking on the objects that are going to be released. This is slowier though, but it's simple and it resolves the aforementioned problems. This is a partial revert of c7c32e7 ("netfilter: nf_tables: defer all object release via rcu") that was introduced in 3.16 to speed up interaction with userspace. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/netfilter')
-rw-r--r--net/netfilter/nf_tables_api.c24
1 files changed, 8 insertions, 16 deletions
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 11ab4b078f3b..66e8425dbfe7 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -3484,13 +3484,8 @@ static void nft_chain_commit_update(struct nft_trans *trans)
}
}
-/* Schedule objects for release via rcu to make sure no packets are accesing
- * removed rules.
- */
-static void nf_tables_commit_release_rcu(struct rcu_head *rt)
+static void nf_tables_commit_release(struct nft_trans *trans)
{
- struct nft_trans *trans = container_of(rt, struct nft_trans, rcu_head);
-
switch (trans->msg_type) {
case NFT_MSG_DELTABLE:
nf_tables_table_destroy(&trans->ctx);
@@ -3612,10 +3607,11 @@ static int nf_tables_commit(struct sk_buff *skb)
}
}
+ synchronize_rcu();
+
list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) {
list_del(&trans->list);
- trans->ctx.nla = NULL;
- call_rcu(&trans->rcu_head, nf_tables_commit_release_rcu);
+ nf_tables_commit_release(trans);
}
nf_tables_gen_notify(net, skb, NFT_MSG_NEWGEN);
@@ -3623,13 +3619,8 @@ static int nf_tables_commit(struct sk_buff *skb)
return 0;
}
-/* Schedule objects for release via rcu to make sure no packets are accesing
- * aborted rules.
- */
-static void nf_tables_abort_release_rcu(struct rcu_head *rt)
+static void nf_tables_abort_release(struct nft_trans *trans)
{
- struct nft_trans *trans = container_of(rt, struct nft_trans, rcu_head);
-
switch (trans->msg_type) {
case NFT_MSG_NEWTABLE:
nf_tables_table_destroy(&trans->ctx);
@@ -3725,11 +3716,12 @@ static int nf_tables_abort(struct sk_buff *skb)
}
}
+ synchronize_rcu();
+
list_for_each_entry_safe_reverse(trans, next,
&net->nft.commit_list, list) {
list_del(&trans->list);
- trans->ctx.nla = NULL;
- call_rcu(&trans->rcu_head, nf_tables_abort_release_rcu);
+ nf_tables_abort_release(trans);
}
return 0;

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