![Dmytro Linkin](/assets/img/avatar_default.png)
Currently init call of all actions (except ipt) init their 'parm'
structure as a direct pointer to nla data in skb. This leads to race
condition when some of the filter actions were initialized successfully
(and were assigned with idr action index that was written directly
into nla data), but then were deleted and retried (due to following
action module missing or classifier-initiated retry), in which case
action init code tries to insert action to idr with index that was
assigned on previous iteration. During retry the index can be reused
by another action that was inserted concurrently, which causes
unintended action sharing between filters.
To fix described race condition, save action idr index to temporary
stack-allocated variable instead on nla data.
Fixes: 0190c1d452
("net: sched: atomically check-allocate action")
Signed-off-by: Dmytro Linkin <dmitrolin@mellanox.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
264 lines
6.5 KiB
C
264 lines
6.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* net/sched/act_connmark.c netfilter connmark retriever action
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* skb mark is over-written
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*
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* Copyright (c) 2011 Felix Fietkau <nbd@openwrt.org>
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/pkt_cls.h>
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#include <linux/ip.h>
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#include <linux/ipv6.h>
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#include <net/netlink.h>
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#include <net/pkt_sched.h>
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#include <net/act_api.h>
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#include <net/pkt_cls.h>
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#include <uapi/linux/tc_act/tc_connmark.h>
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#include <net/tc_act/tc_connmark.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_core.h>
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#include <net/netfilter/nf_conntrack_zones.h>
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static unsigned int connmark_net_id;
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static struct tc_action_ops act_connmark_ops;
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static int tcf_connmark_act(struct sk_buff *skb, const struct tc_action *a,
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struct tcf_result *res)
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{
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const struct nf_conntrack_tuple_hash *thash;
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struct nf_conntrack_tuple tuple;
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enum ip_conntrack_info ctinfo;
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struct tcf_connmark_info *ca = to_connmark(a);
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struct nf_conntrack_zone zone;
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struct nf_conn *c;
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int proto;
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spin_lock(&ca->tcf_lock);
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tcf_lastuse_update(&ca->tcf_tm);
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bstats_update(&ca->tcf_bstats, skb);
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if (skb->protocol == htons(ETH_P_IP)) {
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if (skb->len < sizeof(struct iphdr))
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goto out;
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proto = NFPROTO_IPV4;
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} else if (skb->protocol == htons(ETH_P_IPV6)) {
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if (skb->len < sizeof(struct ipv6hdr))
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goto out;
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proto = NFPROTO_IPV6;
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} else {
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goto out;
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}
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c = nf_ct_get(skb, &ctinfo);
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if (c) {
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skb->mark = c->mark;
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/* using overlimits stats to count how many packets marked */
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ca->tcf_qstats.overlimits++;
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goto out;
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}
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if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb),
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proto, ca->net, &tuple))
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goto out;
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zone.id = ca->zone;
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zone.dir = NF_CT_DEFAULT_ZONE_DIR;
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thash = nf_conntrack_find_get(ca->net, &zone, &tuple);
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if (!thash)
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goto out;
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c = nf_ct_tuplehash_to_ctrack(thash);
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/* using overlimits stats to count how many packets marked */
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ca->tcf_qstats.overlimits++;
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skb->mark = c->mark;
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nf_ct_put(c);
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out:
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spin_unlock(&ca->tcf_lock);
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return ca->tcf_action;
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}
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static const struct nla_policy connmark_policy[TCA_CONNMARK_MAX + 1] = {
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[TCA_CONNMARK_PARMS] = { .len = sizeof(struct tc_connmark) },
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};
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static int tcf_connmark_init(struct net *net, struct nlattr *nla,
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struct nlattr *est, struct tc_action **a,
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int ovr, int bind, bool rtnl_held,
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struct tcf_proto *tp,
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struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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struct nlattr *tb[TCA_CONNMARK_MAX + 1];
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struct tcf_chain *goto_ch = NULL;
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struct tcf_connmark_info *ci;
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struct tc_connmark *parm;
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int ret = 0, err;
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u32 index;
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if (!nla)
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return -EINVAL;
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ret = nla_parse_nested_deprecated(tb, TCA_CONNMARK_MAX, nla,
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connmark_policy, NULL);
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if (ret < 0)
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return ret;
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if (!tb[TCA_CONNMARK_PARMS])
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return -EINVAL;
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parm = nla_data(tb[TCA_CONNMARK_PARMS]);
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index = parm->index;
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ret = tcf_idr_check_alloc(tn, &index, a, bind);
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if (!ret) {
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ret = tcf_idr_create(tn, index, est, a,
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&act_connmark_ops, bind, false);
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if (ret) {
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tcf_idr_cleanup(tn, index);
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return ret;
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}
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ci = to_connmark(*a);
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err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch,
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extack);
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if (err < 0)
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goto release_idr;
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tcf_action_set_ctrlact(*a, parm->action, goto_ch);
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ci->net = net;
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ci->zone = parm->zone;
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tcf_idr_insert(tn, *a);
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ret = ACT_P_CREATED;
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} else if (ret > 0) {
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ci = to_connmark(*a);
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if (bind)
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return 0;
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if (!ovr) {
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tcf_idr_release(*a, bind);
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return -EEXIST;
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}
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err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch,
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extack);
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if (err < 0)
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goto release_idr;
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/* replacing action and zone */
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spin_lock_bh(&ci->tcf_lock);
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goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
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ci->zone = parm->zone;
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spin_unlock_bh(&ci->tcf_lock);
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if (goto_ch)
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tcf_chain_put_by_act(goto_ch);
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ret = 0;
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}
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return ret;
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release_idr:
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tcf_idr_release(*a, bind);
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return err;
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}
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static inline int tcf_connmark_dump(struct sk_buff *skb, struct tc_action *a,
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int bind, int ref)
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{
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unsigned char *b = skb_tail_pointer(skb);
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struct tcf_connmark_info *ci = to_connmark(a);
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struct tc_connmark opt = {
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.index = ci->tcf_index,
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.refcnt = refcount_read(&ci->tcf_refcnt) - ref,
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.bindcnt = atomic_read(&ci->tcf_bindcnt) - bind,
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};
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struct tcf_t t;
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spin_lock_bh(&ci->tcf_lock);
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opt.action = ci->tcf_action;
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opt.zone = ci->zone;
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if (nla_put(skb, TCA_CONNMARK_PARMS, sizeof(opt), &opt))
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goto nla_put_failure;
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tcf_tm_dump(&t, &ci->tcf_tm);
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if (nla_put_64bit(skb, TCA_CONNMARK_TM, sizeof(t), &t,
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TCA_CONNMARK_PAD))
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goto nla_put_failure;
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spin_unlock_bh(&ci->tcf_lock);
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return skb->len;
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nla_put_failure:
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spin_unlock_bh(&ci->tcf_lock);
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nlmsg_trim(skb, b);
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return -1;
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}
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static int tcf_connmark_walker(struct net *net, struct sk_buff *skb,
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struct netlink_callback *cb, int type,
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const struct tc_action_ops *ops,
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struct netlink_ext_ack *extack)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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return tcf_generic_walker(tn, skb, cb, type, ops, extack);
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}
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static int tcf_connmark_search(struct net *net, struct tc_action **a, u32 index)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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return tcf_idr_search(tn, a, index);
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}
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static struct tc_action_ops act_connmark_ops = {
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.kind = "connmark",
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.id = TCA_ID_CONNMARK,
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.owner = THIS_MODULE,
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.act = tcf_connmark_act,
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.dump = tcf_connmark_dump,
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.init = tcf_connmark_init,
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.walk = tcf_connmark_walker,
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.lookup = tcf_connmark_search,
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.size = sizeof(struct tcf_connmark_info),
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};
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static __net_init int connmark_init_net(struct net *net)
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{
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struct tc_action_net *tn = net_generic(net, connmark_net_id);
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return tc_action_net_init(tn, &act_connmark_ops);
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}
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static void __net_exit connmark_exit_net(struct list_head *net_list)
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{
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tc_action_net_exit(net_list, connmark_net_id);
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}
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static struct pernet_operations connmark_net_ops = {
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.init = connmark_init_net,
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.exit_batch = connmark_exit_net,
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.id = &connmark_net_id,
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.size = sizeof(struct tc_action_net),
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};
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static int __init connmark_init_module(void)
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{
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return tcf_register_action(&act_connmark_ops, &connmark_net_ops);
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}
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static void __exit connmark_cleanup_module(void)
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{
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tcf_unregister_action(&act_connmark_ops, &connmark_net_ops);
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}
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module_init(connmark_init_module);
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module_exit(connmark_cleanup_module);
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MODULE_AUTHOR("Felix Fietkau <nbd@openwrt.org>");
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MODULE_DESCRIPTION("Connection tracking mark restoring");
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MODULE_LICENSE("GPL");
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