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net: sched: prevent insertion of new classifiers during chain flush

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Extend tcf_chain with 'flushing' flag. Use the flag to prevent insertion of
new classifier instances when chain flushing is in progress in order to
prevent resource leak when tcf_proto is created by unlocked users
concurrently.

Return EAGAIN error from tcf_chain_tp_insert_unique() to restart
tc_new_tfilter() and lookup the chain/proto again.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Vlad Buslov 2019-02-11 10:55:42 +02:00 committed by David S. Miller
parent 8b64678e0a
commit 726d061286
2 changed files with 30 additions and 6 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/net/sch_generic.h
View file

@ -356,6 +356,7 @@ struct tcf_chain {
unsigned int refcnt; unsigned int refcnt;
unsigned int action_refcnt; unsigned int action_refcnt;
bool explicitly_created; bool explicitly_created;
bool flushing;
const struct tcf_proto_ops *tmplt_ops; const struct tcf_proto_ops *tmplt_ops;
void *tmplt_priv; void *tmplt_priv;
}; };

35
net/sched/cls_api.c
View file

@ -477,9 +477,12 @@ static void __tcf_chain_put(struct tcf_chain *chain, bool by_act,
mutex_unlock(&block->lock); mutex_unlock(&block->lock);
/* The last dropped non-action reference will trigger notification. */ /* The last dropped non-action reference will trigger notification. */
if (is_last && !by_act) if (is_last && !by_act) {
tc_chain_notify_delete(tmplt_ops, tmplt_priv, chain_index, tc_chain_notify_delete(tmplt_ops, tmplt_priv, chain_index,
block, NULL, 0, 0, false); block, NULL, 0, 0, false);
/* Last reference to chain, no need to lock. */
chain->flushing = false;
}
if (refcnt == 0) { if (refcnt == 0) {
tc_chain_tmplt_del(tmplt_ops, tmplt_priv); tc_chain_tmplt_del(tmplt_ops, tmplt_priv);
@ -511,6 +514,7 @@ static void tcf_chain_flush(struct tcf_chain *chain)
tp = tcf_chain_dereference(chain->filter_chain, chain); tp = tcf_chain_dereference(chain->filter_chain, chain);
RCU_INIT_POINTER(chain->filter_chain, NULL); RCU_INIT_POINTER(chain->filter_chain, NULL);
tcf_chain0_head_change(chain, NULL); tcf_chain0_head_change(chain, NULL);
chain->flushing = true;
mutex_unlock(&chain->filter_chain_lock); mutex_unlock(&chain->filter_chain_lock);
while (tp) { while (tp) {
@ -1610,15 +1614,20 @@ static struct tcf_proto *tcf_chain_tp_prev(struct tcf_chain *chain,
return tcf_chain_dereference(*chain_info->pprev, chain); return tcf_chain_dereference(*chain_info->pprev, chain);
} }
static void tcf_chain_tp_insert(struct tcf_chain *chain, static int tcf_chain_tp_insert(struct tcf_chain *chain,
struct tcf_chain_info *chain_info, struct tcf_chain_info *chain_info,
struct tcf_proto *tp) struct tcf_proto *tp)
{ {
if (chain->flushing)
return -EAGAIN;
if (*chain_info->pprev == chain->filter_chain) if (*chain_info->pprev == chain->filter_chain)
tcf_chain0_head_change(chain, tp); tcf_chain0_head_change(chain, tp);
tcf_proto_get(tp); tcf_proto_get(tp);
RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain, chain_info)); RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain, chain_info));
rcu_assign_pointer(*chain_info->pprev, tp); rcu_assign_pointer(*chain_info->pprev, tp);
return 0;
} }
static void tcf_chain_tp_remove(struct tcf_chain *chain, static void tcf_chain_tp_remove(struct tcf_chain *chain,
@ -1649,18 +1658,22 @@ static struct tcf_proto *tcf_chain_tp_insert_unique(struct tcf_chain *chain,
{ {
struct tcf_chain_info chain_info; struct tcf_chain_info chain_info;
struct tcf_proto *tp; struct tcf_proto *tp;
int err = 0;
mutex_lock(&chain->filter_chain_lock); mutex_lock(&chain->filter_chain_lock);
tp = tcf_chain_tp_find(chain, &chain_info, tp = tcf_chain_tp_find(chain, &chain_info,
protocol, prio, false); protocol, prio, false);
if (!tp) if (!tp)
tcf_chain_tp_insert(chain, &chain_info, tp_new); err = tcf_chain_tp_insert(chain, &chain_info, tp_new);
mutex_unlock(&chain->filter_chain_lock); mutex_unlock(&chain->filter_chain_lock);
if (tp) { if (tp) {
tcf_proto_destroy(tp_new, NULL); tcf_proto_destroy(tp_new, NULL);
tp_new = tp; tp_new = tp;
} else if (err) {
tcf_proto_destroy(tp_new, NULL);
tp_new = ERR_PTR(err);
} }
return tp_new; return tp_new;
@ -1943,6 +1956,11 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
if (tp == NULL) { if (tp == NULL) {
struct tcf_proto *tp_new = NULL; struct tcf_proto *tp_new = NULL;
if (chain->flushing) {
err = -EAGAIN;
goto errout_locked;
}
/* Proto-tcf does not exist, create new one */ /* Proto-tcf does not exist, create new one */
if (tca[TCA_KIND] == NULL || !protocol) { if (tca[TCA_KIND] == NULL || !protocol) {
@ -1966,11 +1984,15 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
protocol, prio, chain, extack); protocol, prio, chain, extack);
if (IS_ERR(tp_new)) { if (IS_ERR(tp_new)) {
err = PTR_ERR(tp_new); err = PTR_ERR(tp_new);
goto errout; goto errout_tp;
} }
tp_created = 1; tp_created = 1;
tp = tcf_chain_tp_insert_unique(chain, tp_new, protocol, prio); tp = tcf_chain_tp_insert_unique(chain, tp_new, protocol, prio);
if (IS_ERR(tp)) {
err = PTR_ERR(tp);
goto errout_tp;
}
} else { } else {
mutex_unlock(&chain->filter_chain_lock); mutex_unlock(&chain->filter_chain_lock);
} }
@ -2011,6 +2033,7 @@ static int tc_new_tfilter(struct sk_buff *skb, struct nlmsghdr *n,
errout: errout:
if (err && tp_created) if (err && tp_created)
tcf_chain_tp_delete_empty(chain, tp, NULL); tcf_chain_tp_delete_empty(chain, tp, NULL);
errout_tp:
if (chain) { if (chain) {
if (tp && !IS_ERR(tp)) if (tp && !IS_ERR(tp))
tcf_proto_put(tp, NULL); tcf_proto_put(tp, NULL);