linux/net/sched/act_mirred.c
Cong Wang e49d8c22f1 net_sched: defer tcf_idr_insert() in tcf_action_init_1()
All TC actions call tcf_idr_insert() for new action at the end
of their ->init(), so we can actually move it to a central place
in tcf_action_init_1().

And once the action is inserted into the global IDR, other parallel
process could free it immediately as its refcnt is still 1, so we can
not fail after this, we need to move it after the goto action
validation to avoid handling the failure case after insertion.

This is found during code review, is not directly triggered by syzbot.
And this prepares for the next patch.

Cc: Vlad Buslov <vladbu@mellanox.com>
Cc: Jamal Hadi Salim <jhs@mojatatu.com>
Cc: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-09-24 19:46:21 -07:00

497 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* net/sched/act_mirred.c packet mirroring and redirect actions
*
* Authors: Jamal Hadi Salim (2002-4)
*
* TODO: Add ingress support (and socket redirect support)
*/
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/gfp.h>
#include <linux/if_arp.h>
#include <net/net_namespace.h>
#include <net/netlink.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
#include <linux/tc_act/tc_mirred.h>
#include <net/tc_act/tc_mirred.h>
static LIST_HEAD(mirred_list);
static DEFINE_SPINLOCK(mirred_list_lock);
#define MIRRED_RECURSION_LIMIT 4
static DEFINE_PER_CPU(unsigned int, mirred_rec_level);
static bool tcf_mirred_is_act_redirect(int action)
{
return action == TCA_EGRESS_REDIR || action == TCA_INGRESS_REDIR;
}
static bool tcf_mirred_act_wants_ingress(int action)
{
switch (action) {
case TCA_EGRESS_REDIR:
case TCA_EGRESS_MIRROR:
return false;
case TCA_INGRESS_REDIR:
case TCA_INGRESS_MIRROR:
return true;
default:
BUG();
}
}
static bool tcf_mirred_can_reinsert(int action)
{
switch (action) {
case TC_ACT_SHOT:
case TC_ACT_STOLEN:
case TC_ACT_QUEUED:
case TC_ACT_TRAP:
return true;
}
return false;
}
static struct net_device *tcf_mirred_dev_dereference(struct tcf_mirred *m)
{
return rcu_dereference_protected(m->tcfm_dev,
lockdep_is_held(&m->tcf_lock));
}
static void tcf_mirred_release(struct tc_action *a)
{
struct tcf_mirred *m = to_mirred(a);
struct net_device *dev;
spin_lock(&mirred_list_lock);
list_del(&m->tcfm_list);
spin_unlock(&mirred_list_lock);
/* last reference to action, no need to lock */
dev = rcu_dereference_protected(m->tcfm_dev, 1);
if (dev)
dev_put(dev);
}
static const struct nla_policy mirred_policy[TCA_MIRRED_MAX + 1] = {
[TCA_MIRRED_PARMS] = { .len = sizeof(struct tc_mirred) },
};
static unsigned int mirred_net_id;
static struct tc_action_ops act_mirred_ops;
static int tcf_mirred_init(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **a,
int ovr, int bind, bool rtnl_held,
struct tcf_proto *tp,
u32 flags, struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, mirred_net_id);
struct nlattr *tb[TCA_MIRRED_MAX + 1];
struct tcf_chain *goto_ch = NULL;
bool mac_header_xmit = false;
struct tc_mirred *parm;
struct tcf_mirred *m;
struct net_device *dev;
bool exists = false;
int ret, err;
u32 index;
if (!nla) {
NL_SET_ERR_MSG_MOD(extack, "Mirred requires attributes to be passed");
return -EINVAL;
}
ret = nla_parse_nested_deprecated(tb, TCA_MIRRED_MAX, nla,
mirred_policy, extack);
if (ret < 0)
return ret;
if (!tb[TCA_MIRRED_PARMS]) {
NL_SET_ERR_MSG_MOD(extack, "Missing required mirred parameters");
return -EINVAL;
}
parm = nla_data(tb[TCA_MIRRED_PARMS]);
index = parm->index;
err = tcf_idr_check_alloc(tn, &index, a, bind);
if (err < 0)
return err;
exists = err;
if (exists && bind)
return 0;
switch (parm->eaction) {
case TCA_EGRESS_MIRROR:
case TCA_EGRESS_REDIR:
case TCA_INGRESS_REDIR:
case TCA_INGRESS_MIRROR:
break;
default:
if (exists)
tcf_idr_release(*a, bind);
else
tcf_idr_cleanup(tn, index);
NL_SET_ERR_MSG_MOD(extack, "Unknown mirred option");
return -EINVAL;
}
if (!exists) {
if (!parm->ifindex) {
tcf_idr_cleanup(tn, index);
NL_SET_ERR_MSG_MOD(extack, "Specified device does not exist");
return -EINVAL;
}
ret = tcf_idr_create_from_flags(tn, index, est, a,
&act_mirred_ops, bind, flags);
if (ret) {
tcf_idr_cleanup(tn, index);
return ret;
}
ret = ACT_P_CREATED;
} else if (!ovr) {
tcf_idr_release(*a, bind);
return -EEXIST;
}
m = to_mirred(*a);
if (ret == ACT_P_CREATED)
INIT_LIST_HEAD(&m->tcfm_list);
err = tcf_action_check_ctrlact(parm->action, tp, &goto_ch, extack);
if (err < 0)
goto release_idr;
spin_lock_bh(&m->tcf_lock);
if (parm->ifindex) {
dev = dev_get_by_index(net, parm->ifindex);
if (!dev) {
spin_unlock_bh(&m->tcf_lock);
err = -ENODEV;
goto put_chain;
}
mac_header_xmit = dev_is_mac_header_xmit(dev);
dev = rcu_replace_pointer(m->tcfm_dev, dev,
lockdep_is_held(&m->tcf_lock));
if (dev)
dev_put(dev);
m->tcfm_mac_header_xmit = mac_header_xmit;
}
goto_ch = tcf_action_set_ctrlact(*a, parm->action, goto_ch);
m->tcfm_eaction = parm->eaction;
spin_unlock_bh(&m->tcf_lock);
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
if (ret == ACT_P_CREATED) {
spin_lock(&mirred_list_lock);
list_add(&m->tcfm_list, &mirred_list);
spin_unlock(&mirred_list_lock);
}
return ret;
put_chain:
if (goto_ch)
tcf_chain_put_by_act(goto_ch);
release_idr:
tcf_idr_release(*a, bind);
return err;
}
static int tcf_mirred_act(struct sk_buff *skb, const struct tc_action *a,
struct tcf_result *res)
{
struct tcf_mirred *m = to_mirred(a);
struct sk_buff *skb2 = skb;
bool m_mac_header_xmit;
struct net_device *dev;
unsigned int rec_level;
int retval, err = 0;
bool use_reinsert;
bool want_ingress;
bool is_redirect;
bool expects_nh;
int m_eaction;
int mac_len;
bool at_nh;
rec_level = __this_cpu_inc_return(mirred_rec_level);
if (unlikely(rec_level > MIRRED_RECURSION_LIMIT)) {
net_warn_ratelimited("Packet exceeded mirred recursion limit on dev %s\n",
netdev_name(skb->dev));
__this_cpu_dec(mirred_rec_level);
return TC_ACT_SHOT;
}
tcf_lastuse_update(&m->tcf_tm);
tcf_action_update_bstats(&m->common, skb);
m_mac_header_xmit = READ_ONCE(m->tcfm_mac_header_xmit);
m_eaction = READ_ONCE(m->tcfm_eaction);
retval = READ_ONCE(m->tcf_action);
dev = rcu_dereference_bh(m->tcfm_dev);
if (unlikely(!dev)) {
pr_notice_once("tc mirred: target device is gone\n");
goto out;
}
if (unlikely(!(dev->flags & IFF_UP))) {
net_notice_ratelimited("tc mirred to Houston: device %s is down\n",
dev->name);
goto out;
}
/* we could easily avoid the clone only if called by ingress and clsact;
* since we can't easily detect the clsact caller, skip clone only for
* ingress - that covers the TC S/W datapath.
*/
is_redirect = tcf_mirred_is_act_redirect(m_eaction);
use_reinsert = skb_at_tc_ingress(skb) && is_redirect &&
tcf_mirred_can_reinsert(retval);
if (!use_reinsert) {
skb2 = skb_clone(skb, GFP_ATOMIC);
if (!skb2)
goto out;
}
want_ingress = tcf_mirred_act_wants_ingress(m_eaction);
expects_nh = want_ingress || !m_mac_header_xmit;
at_nh = skb->data == skb_network_header(skb);
if (at_nh != expects_nh) {
mac_len = skb_at_tc_ingress(skb) ? skb->mac_len :
skb_network_header(skb) - skb_mac_header(skb);
if (expects_nh) {
/* target device/action expect data at nh */
skb_pull_rcsum(skb2, mac_len);
} else {
/* target device/action expect data at mac */
skb_push_rcsum(skb2, mac_len);
}
}
skb2->skb_iif = skb->dev->ifindex;
skb2->dev = dev;
/* mirror is always swallowed */
if (is_redirect) {
skb_set_redirected(skb2, skb2->tc_at_ingress);
/* let's the caller reinsert the packet, if possible */
if (use_reinsert) {
res->ingress = want_ingress;
if (skb_tc_reinsert(skb, res))
tcf_action_inc_overlimit_qstats(&m->common);
__this_cpu_dec(mirred_rec_level);
return TC_ACT_CONSUMED;
}
}
if (!want_ingress)
err = dev_queue_xmit(skb2);
else
err = netif_receive_skb(skb2);
if (err) {
out:
tcf_action_inc_overlimit_qstats(&m->common);
if (tcf_mirred_is_act_redirect(m_eaction))
retval = TC_ACT_SHOT;
}
__this_cpu_dec(mirred_rec_level);
return retval;
}
static void tcf_stats_update(struct tc_action *a, u64 bytes, u64 packets,
u64 drops, u64 lastuse, bool hw)
{
struct tcf_mirred *m = to_mirred(a);
struct tcf_t *tm = &m->tcf_tm;
tcf_action_update_stats(a, bytes, packets, drops, hw);
tm->lastuse = max_t(u64, tm->lastuse, lastuse);
}
static int tcf_mirred_dump(struct sk_buff *skb, struct tc_action *a, int bind,
int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_mirred *m = to_mirred(a);
struct tc_mirred opt = {
.index = m->tcf_index,
.refcnt = refcount_read(&m->tcf_refcnt) - ref,
.bindcnt = atomic_read(&m->tcf_bindcnt) - bind,
};
struct net_device *dev;
struct tcf_t t;
spin_lock_bh(&m->tcf_lock);
opt.action = m->tcf_action;
opt.eaction = m->tcfm_eaction;
dev = tcf_mirred_dev_dereference(m);
if (dev)
opt.ifindex = dev->ifindex;
if (nla_put(skb, TCA_MIRRED_PARMS, sizeof(opt), &opt))
goto nla_put_failure;
tcf_tm_dump(&t, &m->tcf_tm);
if (nla_put_64bit(skb, TCA_MIRRED_TM, sizeof(t), &t, TCA_MIRRED_PAD))
goto nla_put_failure;
spin_unlock_bh(&m->tcf_lock);
return skb->len;
nla_put_failure:
spin_unlock_bh(&m->tcf_lock);
nlmsg_trim(skb, b);
return -1;
}
static int tcf_mirred_walker(struct net *net, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack)
{
struct tc_action_net *tn = net_generic(net, mirred_net_id);
return tcf_generic_walker(tn, skb, cb, type, ops, extack);
}
static int tcf_mirred_search(struct net *net, struct tc_action **a, u32 index)
{
struct tc_action_net *tn = net_generic(net, mirred_net_id);
return tcf_idr_search(tn, a, index);
}
static int mirred_device_event(struct notifier_block *unused,
unsigned long event, void *ptr)
{
struct net_device *dev = netdev_notifier_info_to_dev(ptr);
struct tcf_mirred *m;
ASSERT_RTNL();
if (event == NETDEV_UNREGISTER) {
spin_lock(&mirred_list_lock);
list_for_each_entry(m, &mirred_list, tcfm_list) {
spin_lock_bh(&m->tcf_lock);
if (tcf_mirred_dev_dereference(m) == dev) {
dev_put(dev);
/* Note : no rcu grace period necessary, as
* net_device are already rcu protected.
*/
RCU_INIT_POINTER(m->tcfm_dev, NULL);
}
spin_unlock_bh(&m->tcf_lock);
}
spin_unlock(&mirred_list_lock);
}
return NOTIFY_DONE;
}
static struct notifier_block mirred_device_notifier = {
.notifier_call = mirred_device_event,
};
static void tcf_mirred_dev_put(void *priv)
{
struct net_device *dev = priv;
dev_put(dev);
}
static struct net_device *
tcf_mirred_get_dev(const struct tc_action *a,
tc_action_priv_destructor *destructor)
{
struct tcf_mirred *m = to_mirred(a);
struct net_device *dev;
rcu_read_lock();
dev = rcu_dereference(m->tcfm_dev);
if (dev) {
dev_hold(dev);
*destructor = tcf_mirred_dev_put;
}
rcu_read_unlock();
return dev;
}
static size_t tcf_mirred_get_fill_size(const struct tc_action *act)
{
return nla_total_size(sizeof(struct tc_mirred));
}
static struct tc_action_ops act_mirred_ops = {
.kind = "mirred",
.id = TCA_ID_MIRRED,
.owner = THIS_MODULE,
.act = tcf_mirred_act,
.stats_update = tcf_stats_update,
.dump = tcf_mirred_dump,
.cleanup = tcf_mirred_release,
.init = tcf_mirred_init,
.walk = tcf_mirred_walker,
.lookup = tcf_mirred_search,
.get_fill_size = tcf_mirred_get_fill_size,
.size = sizeof(struct tcf_mirred),
.get_dev = tcf_mirred_get_dev,
};
static __net_init int mirred_init_net(struct net *net)
{
struct tc_action_net *tn = net_generic(net, mirred_net_id);
return tc_action_net_init(net, tn, &act_mirred_ops);
}
static void __net_exit mirred_exit_net(struct list_head *net_list)
{
tc_action_net_exit(net_list, mirred_net_id);
}
static struct pernet_operations mirred_net_ops = {
.init = mirred_init_net,
.exit_batch = mirred_exit_net,
.id = &mirred_net_id,
.size = sizeof(struct tc_action_net),
};
MODULE_AUTHOR("Jamal Hadi Salim(2002)");
MODULE_DESCRIPTION("Device Mirror/redirect actions");
MODULE_LICENSE("GPL");
static int __init mirred_init_module(void)
{
int err = register_netdevice_notifier(&mirred_device_notifier);
if (err)
return err;
pr_info("Mirror/redirect action on\n");
err = tcf_register_action(&act_mirred_ops, &mirred_net_ops);
if (err)
unregister_netdevice_notifier(&mirred_device_notifier);
return err;
}
static void __exit mirred_cleanup_module(void)
{
tcf_unregister_action(&act_mirred_ops, &mirred_net_ops);
unregister_netdevice_notifier(&mirred_device_notifier);
}
module_init(mirred_init_module);
module_exit(mirred_cleanup_module);