From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Buslov Subject: [PATCH net-next v6 04/11] net: sched: always take reference to action Date: Thu, 5 Jul 2018 17:24:26 +0300 Message-ID: <1530800673-12280-5-git-send-email-vladbu@mellanox.com> References: <1530800673-12280-1-git-send-email-vladbu@mellanox.com> Cc: davem@davemloft.net, jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us, ast@kernel.org, daniel@iogearbox.net, kliteyn@mellanox.com, Vlad Buslov , Jiri Pirko To: netdev@vger.kernel.org Return-path: Received: from mail-il-dmz.mellanox.com ([193.47.165.129]:51355 "EHLO mellanox.co.il" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753418AbeGEOYq (ORCPT ); Thu, 5 Jul 2018 10:24:46 -0400 In-Reply-To: <1530800673-12280-1-git-send-email-vladbu@mellanox.com> Sender: netdev-owner@vger.kernel.org List-ID: Without rtnl lock protection it is no longer safe to use pointer to tc action without holding reference to it. (it can be destroyed concurrently) Remove unsafe action idr lookup function. Instead of it, implement safe tcf idr check function that atomically looks up action in idr and increments its reference and bind counters. Implement both action search and check using new safe function Reference taken by idr check is temporal and should not be accounted by userspace clients (both logically and to preserver current API behavior). Subtract temporal reference when dumping action to userspace using existing tca_get_fill function arguments. Reviewed-by: Marcelo Ricardo Leitner Signed-off-by: Vlad Buslov Signed-off-by: Jiri Pirko --- Changes from V1 to V2: - Make __tcf_idr_check function static - Merge changes that take reference to action when performing lookup and changes that account for this additional reference when dumping action to user space into single patch. net/sched/act_api.c | 46 ++++++++++++++++++++-------------------------- 1 file changed, 20 insertions(+), 26 deletions(-) diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 256b0c93916c..aa304d36fee0 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -284,44 +284,38 @@ int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb, } EXPORT_SYMBOL(tcf_generic_walker); -static struct tc_action *tcf_idr_lookup(u32 index, struct tcf_idrinfo *idrinfo) +static bool __tcf_idr_check(struct tc_action_net *tn, u32 index, + struct tc_action **a, int bind) { - struct tc_action *p = NULL; + struct tcf_idrinfo *idrinfo = tn->idrinfo; + struct tc_action *p; spin_lock(&idrinfo->lock); p = idr_find(&idrinfo->action_idr, index); + if (p) { + refcount_inc(&p->tcfa_refcnt); + if (bind) + atomic_inc(&p->tcfa_bindcnt); + } spin_unlock(&idrinfo->lock); - return p; + if (p) { + *a = p; + return true; + } + return false; } int tcf_idr_search(struct tc_action_net *tn, struct tc_action **a, u32 index) { - struct tcf_idrinfo *idrinfo = tn->idrinfo; - struct tc_action *p = tcf_idr_lookup(index, idrinfo); - - if (p) { - *a = p; - return 1; - } - return 0; + return __tcf_idr_check(tn, index, a, 0); } EXPORT_SYMBOL(tcf_idr_search); bool tcf_idr_check(struct tc_action_net *tn, u32 index, struct tc_action **a, int bind) { - struct tcf_idrinfo *idrinfo = tn->idrinfo; - struct tc_action *p = tcf_idr_lookup(index, idrinfo); - - if (index && p) { - if (bind) - atomic_inc(&p->tcfa_bindcnt); - refcount_inc(&p->tcfa_refcnt); - *a = p; - return true; - } - return false; + return __tcf_idr_check(tn, index, a, bind); } EXPORT_SYMBOL(tcf_idr_check); @@ -932,7 +926,7 @@ tcf_get_notify(struct net *net, u32 portid, struct nlmsghdr *n, if (!skb) return -ENOBUFS; if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, event, - 0, 0) <= 0) { + 0, 1) <= 0) { NL_SET_ERR_MSG(extack, "Failed to fill netlink attributes while adding TC action"); kfree_skb(skb); return -EINVAL; @@ -1072,7 +1066,7 @@ tcf_del_notify(struct net *net, struct nlmsghdr *n, struct list_head *actions, return -ENOBUFS; if (tca_get_fill(skb, actions, portid, n->nlmsg_seq, 0, RTM_DELACTION, - 0, 1) <= 0) { + 0, 2) <= 0) { NL_SET_ERR_MSG(extack, "Failed to fill netlink TC action attributes"); kfree_skb(skb); return -EINVAL; @@ -1131,14 +1125,14 @@ tca_action_gd(struct net *net, struct nlattr *nla, struct nlmsghdr *n, if (event == RTM_GETACTION) ret = tcf_get_notify(net, portid, n, &actions, event, extack); else { /* delete */ + cleanup_a(&actions, 1); /* lookup took reference */ ret = tcf_del_notify(net, n, &actions, portid, attr_size, extack); if (ret) goto err; return ret; } err: - if (event != RTM_GETACTION) - tcf_action_destroy(&actions, 0); + tcf_action_destroy(&actions, 0); return ret; } -- 2.7.5