From 726d061286ceeeabda54ba6f080d0cb8f187a9d7 Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Mon, 11 Feb 2019 10:55:42 +0200 Subject: net: sched: prevent insertion of new classifiers during chain flush 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 Acked-by: Jiri Pirko Signed-off-by: David S. Miller --- net/sched/cls_api.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) (limited to 'net/sched/cls_api.c') diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index c6452e3bfc6a..3038a82f6591 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -477,9 +477,12 @@ static void __tcf_chain_put(struct tcf_chain *chain, bool by_act, mutex_unlock(&block->lock); /* 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, block, NULL, 0, 0, false); + /* Last reference to chain, no need to lock. */ + chain->flushing = false; + } if (refcnt == 0) { 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); RCU_INIT_POINTER(chain->filter_chain, NULL); tcf_chain0_head_change(chain, NULL); + chain->flushing = true; mutex_unlock(&chain->filter_chain_lock); 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); } -static void tcf_chain_tp_insert(struct tcf_chain *chain, - struct tcf_chain_info *chain_info, - struct tcf_proto *tp) +static int tcf_chain_tp_insert(struct tcf_chain *chain, + struct tcf_chain_info *chain_info, + struct tcf_proto *tp) { + if (chain->flushing) + return -EAGAIN; + if (*chain_info->pprev == chain->filter_chain) tcf_chain0_head_change(chain, tp); tcf_proto_get(tp); RCU_INIT_POINTER(tp->next, tcf_chain_tp_prev(chain, chain_info)); rcu_assign_pointer(*chain_info->pprev, tp); + + return 0; } 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_proto *tp; + int err = 0; mutex_lock(&chain->filter_chain_lock); tp = tcf_chain_tp_find(chain, &chain_info, protocol, prio, false); 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); if (tp) { tcf_proto_destroy(tp_new, NULL); tp_new = tp; + } else if (err) { + tcf_proto_destroy(tp_new, NULL); + tp_new = ERR_PTR(err); } return tp_new; @@ -1943,6 +1956,11 @@ replay: if (tp == NULL) { struct tcf_proto *tp_new = NULL; + if (chain->flushing) { + err = -EAGAIN; + goto errout_locked; + } + /* Proto-tcf does not exist, create new one */ if (tca[TCA_KIND] == NULL || !protocol) { @@ -1966,11 +1984,15 @@ replay: protocol, prio, chain, extack); if (IS_ERR(tp_new)) { err = PTR_ERR(tp_new); - goto errout; + goto errout_tp; } tp_created = 1; tp = tcf_chain_tp_insert_unique(chain, tp_new, protocol, prio); + if (IS_ERR(tp)) { + err = PTR_ERR(tp); + goto errout_tp; + } } else { mutex_unlock(&chain->filter_chain_lock); } @@ -2011,6 +2033,7 @@ replay: errout: if (err && tp_created) tcf_chain_tp_delete_empty(chain, tp, NULL); +errout_tp: if (chain) { if (tp && !IS_ERR(tp)) tcf_proto_put(tp, NULL); -- cgit v1.2.3-59-g8ed1b