From 81692c6add7e55309bdc275f59301efd4b49e958 Mon Sep 17 00:00:00 2001 From: Vlad Buslov Date: Wed, 7 Apr 2021 18:36:03 +0300 Subject: [PATCH] net: sched: fix action overwrite reference counting commit 87c750e8c38bce706eb32e4d8f1e3402f2cebbd4 upstream. Action init code increments reference counter when it changes an action. This is the desired behavior for cls API which needs to obtain action reference for every classifier that points to action. However, act API just needs to change the action and releases the reference before returning. This sequence breaks when the requested action doesn't exist, which causes act API init code to create new action with specified index, but action is still released before returning and is deleted (unless it was referenced concurrently by cls API). Reproduction: $ sudo tc actions ls action gact $ sudo tc actions change action gact drop index 1 $ sudo tc actions ls action gact Extend tcf_action_init() to accept 'init_res' array and initialize it with action->ops->init() result. In tcf_action_add() remove pointers to created actions from actions array before passing it to tcf_action_put_many(). Fixes: cae422f379f3 ("net: sched: use reference counting action init") Reported-by: Kumar Kartikeya Dwivedi Signed-off-by: Vlad Buslov Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- include/net/act_api.h | 5 +++-- net/sched/act_api.c | 22 +++++++++++++++------- net/sched/cls_api.c | 9 +++++---- 3 files changed, 23 insertions(+), 13 deletions(-) diff --git a/include/net/act_api.h b/include/net/act_api.h index 89b42a1..2778609 100644 --- a/include/net/act_api.h +++ b/include/net/act_api.h @@ -185,7 +185,7 @@ int tcf_action_exec(struct sk_buff *skb, struct tc_action **actions, int nr_actions, struct tcf_result *res); int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action *actions[], size_t *attr_size, + struct tc_action *actions[], int init_res[], size_t *attr_size, bool rtnl_held, struct netlink_ext_ack *extack); struct tc_action_ops *tc_action_load_ops(char *name, struct nlattr *nla, bool rtnl_held, @@ -193,7 +193,8 @@ struct tc_action_ops *tc_action_load_ops(char *name, struct nlattr *nla, struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action_ops *ops, bool rtnl_held, + struct tc_action_ops *a_o, int *init_res, + bool rtnl_held, struct netlink_ext_ack *extack); int tcf_action_dump(struct sk_buff *skb, struct tc_action *actions[], int bind, int ref, bool terse); diff --git a/net/sched/act_api.c b/net/sched/act_api.c index 181c4b5..df1e494 100644 --- a/net/sched/act_api.c +++ b/net/sched/act_api.c @@ -972,7 +972,8 @@ struct tc_action_ops *tc_action_load_ops(char *name, struct nlattr *nla, struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action_ops *a_o, bool rtnl_held, + struct tc_action_ops *a_o, int *init_res, + bool rtnl_held, struct netlink_ext_ack *extack) { struct nla_bitfield32 flags = { 0, 0 }; @@ -1008,6 +1009,7 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp, } if (err < 0) goto err_out; + *init_res = err; if (!name && tb[TCA_ACT_COOKIE]) tcf_set_action_cookie(&a->act_cookie, cookie); @@ -1036,7 +1038,7 @@ err_out: int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla, struct nlattr *est, char *name, int ovr, int bind, - struct tc_action *actions[], size_t *attr_size, + struct tc_action *actions[], int init_res[], size_t *attr_size, bool rtnl_held, struct netlink_ext_ack *extack) { struct tc_action_ops *ops[TCA_ACT_MAX_PRIO] = {}; @@ -1064,7 +1066,8 @@ int tcf_action_init(struct net *net, struct tcf_proto *tp, struct nlattr *nla, for (i = 1; i <= TCA_ACT_MAX_PRIO && tb[i]; i++) { act = tcf_action_init_1(net, tp, tb[i], est, name, ovr, bind, - ops[i - 1], rtnl_held, extack); + ops[i - 1], &init_res[i - 1], rtnl_held, + extack); if (IS_ERR(act)) { err = PTR_ERR(act); goto err; @@ -1477,12 +1480,13 @@ static int tcf_action_add(struct net *net, struct nlattr *nla, struct netlink_ext_ack *extack) { size_t attr_size = 0; - int loop, ret; + int loop, ret, i; struct tc_action *actions[TCA_ACT_MAX_PRIO] = {}; + int init_res[TCA_ACT_MAX_PRIO] = {}; for (loop = 0; loop < 10; loop++) { ret = tcf_action_init(net, NULL, nla, NULL, NULL, ovr, 0, - actions, &attr_size, true, extack); + actions, init_res, &attr_size, true, extack); if (ret != -EAGAIN) break; } @@ -1490,8 +1494,12 @@ static int tcf_action_add(struct net *net, struct nlattr *nla, if (ret < 0) return ret; ret = tcf_add_notify(net, n, actions, portid, attr_size, extack); - if (ovr) - tcf_action_put_many(actions); + + /* only put existing actions */ + for (i = 0; i < TCA_ACT_MAX_PRIO; i++) + if (init_res[i] == ACT_P_CREATED) + actions[i] = NULL; + tcf_action_put_many(actions); return ret; } diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c index b2b7834..b45eb7f 100644 --- a/net/sched/cls_api.c +++ b/net/sched/cls_api.c @@ -3051,6 +3051,7 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, { #ifdef CONFIG_NET_CLS_ACT { + int init_res[TCA_ACT_MAX_PRIO] = {}; struct tc_action *act; size_t attr_size = 0; @@ -3062,8 +3063,8 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, return PTR_ERR(a_o); act = tcf_action_init_1(net, tp, tb[exts->police], rate_tlv, "police", ovr, - TCA_ACT_BIND, a_o, rtnl_held, - extack); + TCA_ACT_BIND, a_o, init_res, + rtnl_held, extack); if (IS_ERR(act)) { module_put(a_o->owner); return PTR_ERR(act); @@ -3078,8 +3079,8 @@ int tcf_exts_validate(struct net *net, struct tcf_proto *tp, struct nlattr **tb, err = tcf_action_init(net, tp, tb[exts->action], rate_tlv, NULL, ovr, TCA_ACT_BIND, - exts->actions, &attr_size, - rtnl_held, extack); + exts->actions, init_res, + &attr_size, rtnl_held, extack); if (err < 0) return err; exts->nr_actions = err; -- 2.7.4