linux/net/sched/act_police.c
Eric Dumazet c7de2cf053 pkt_sched: gen_kill_estimator() rcu fixes
gen_kill_estimator() API is incomplete or not well documented, since
caller should make sure an RCU grace period is respected before
freeing stats_lock.

This was partially addressed in commit 5d944c640b
(gen_estimator: deadlock fix), but same problem exist for all
gen_kill_estimator() users, if lock they use is not already RCU
protected.

A code review shows xt_RATEEST.c, act_api.c, act_police.c have this
problem. Other are ok because they use qdisc lock, already RCU
protected.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-06-11 18:37:08 -07:00

414 lines
10 KiB
C

/*
* net/sched/police.c Input police filter.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
* J Hadi Salim (action changes)
*/
#include <linux/module.h>
#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/init.h>
#include <linux/slab.h>
#include <net/act_api.h>
#include <net/netlink.h>
#define L2T(p,L) qdisc_l2t((p)->tcfp_R_tab, L)
#define L2T_P(p,L) qdisc_l2t((p)->tcfp_P_tab, L)
#define POL_TAB_MASK 15
static struct tcf_common *tcf_police_ht[POL_TAB_MASK + 1];
static u32 police_idx_gen;
static DEFINE_RWLOCK(police_lock);
static struct tcf_hashinfo police_hash_info = {
.htab = tcf_police_ht,
.hmask = POL_TAB_MASK,
.lock = &police_lock,
};
/* old policer structure from before tc actions */
struct tc_police_compat
{
u32 index;
int action;
u32 limit;
u32 burst;
u32 mtu;
struct tc_ratespec rate;
struct tc_ratespec peakrate;
};
/* Each policer is serialized by its individual spinlock */
static int tcf_act_police_walker(struct sk_buff *skb, struct netlink_callback *cb,
int type, struct tc_action *a)
{
struct tcf_common *p;
int err = 0, index = -1, i = 0, s_i = 0, n_i = 0;
struct nlattr *nest;
read_lock_bh(&police_lock);
s_i = cb->args[0];
for (i = 0; i < (POL_TAB_MASK + 1); i++) {
p = tcf_police_ht[tcf_hash(i, POL_TAB_MASK)];
for (; p; p = p->tcfc_next) {
index++;
if (index < s_i)
continue;
a->priv = p;
a->order = index;
nest = nla_nest_start(skb, a->order);
if (nest == NULL)
goto nla_put_failure;
if (type == RTM_DELACTION)
err = tcf_action_dump_1(skb, a, 0, 1);
else
err = tcf_action_dump_1(skb, a, 0, 0);
if (err < 0) {
index--;
nla_nest_cancel(skb, nest);
goto done;
}
nla_nest_end(skb, nest);
n_i++;
}
}
done:
read_unlock_bh(&police_lock);
if (n_i)
cb->args[0] += n_i;
return n_i;
nla_put_failure:
nla_nest_cancel(skb, nest);
goto done;
}
static void tcf_police_free_rcu(struct rcu_head *head)
{
kfree(container_of(head, struct tcf_police, tcf_rcu));
}
static void tcf_police_destroy(struct tcf_police *p)
{
unsigned int h = tcf_hash(p->tcf_index, POL_TAB_MASK);
struct tcf_common **p1p;
for (p1p = &tcf_police_ht[h]; *p1p; p1p = &(*p1p)->tcfc_next) {
if (*p1p == &p->common) {
write_lock_bh(&police_lock);
*p1p = p->tcf_next;
write_unlock_bh(&police_lock);
gen_kill_estimator(&p->tcf_bstats,
&p->tcf_rate_est);
if (p->tcfp_R_tab)
qdisc_put_rtab(p->tcfp_R_tab);
if (p->tcfp_P_tab)
qdisc_put_rtab(p->tcfp_P_tab);
/*
* gen_estimator est_timer() might access p->tcf_lock
* or bstats, wait a RCU grace period before freeing p
*/
call_rcu(&p->tcf_rcu, tcf_police_free_rcu);
return;
}
}
WARN_ON(1);
}
static const struct nla_policy police_policy[TCA_POLICE_MAX + 1] = {
[TCA_POLICE_RATE] = { .len = TC_RTAB_SIZE },
[TCA_POLICE_PEAKRATE] = { .len = TC_RTAB_SIZE },
[TCA_POLICE_AVRATE] = { .type = NLA_U32 },
[TCA_POLICE_RESULT] = { .type = NLA_U32 },
};
static int tcf_act_police_locate(struct nlattr *nla, struct nlattr *est,
struct tc_action *a, int ovr, int bind)
{
unsigned h;
int ret = 0, err;
struct nlattr *tb[TCA_POLICE_MAX + 1];
struct tc_police *parm;
struct tcf_police *police;
struct qdisc_rate_table *R_tab = NULL, *P_tab = NULL;
int size;
if (nla == NULL)
return -EINVAL;
err = nla_parse_nested(tb, TCA_POLICE_MAX, nla, police_policy);
if (err < 0)
return err;
if (tb[TCA_POLICE_TBF] == NULL)
return -EINVAL;
size = nla_len(tb[TCA_POLICE_TBF]);
if (size != sizeof(*parm) && size != sizeof(struct tc_police_compat))
return -EINVAL;
parm = nla_data(tb[TCA_POLICE_TBF]);
if (parm->index) {
struct tcf_common *pc;
pc = tcf_hash_lookup(parm->index, &police_hash_info);
if (pc != NULL) {
a->priv = pc;
police = to_police(pc);
if (bind) {
police->tcf_bindcnt += 1;
police->tcf_refcnt += 1;
}
if (ovr)
goto override;
return ret;
}
}
police = kzalloc(sizeof(*police), GFP_KERNEL);
if (police == NULL)
return -ENOMEM;
ret = ACT_P_CREATED;
police->tcf_refcnt = 1;
spin_lock_init(&police->tcf_lock);
if (bind)
police->tcf_bindcnt = 1;
override:
if (parm->rate.rate) {
err = -ENOMEM;
R_tab = qdisc_get_rtab(&parm->rate, tb[TCA_POLICE_RATE]);
if (R_tab == NULL)
goto failure;
if (parm->peakrate.rate) {
P_tab = qdisc_get_rtab(&parm->peakrate,
tb[TCA_POLICE_PEAKRATE]);
if (P_tab == NULL)
goto failure;
}
}
spin_lock_bh(&police->tcf_lock);
if (est) {
err = gen_replace_estimator(&police->tcf_bstats,
&police->tcf_rate_est,
&police->tcf_lock, est);
if (err)
goto failure_unlock;
} else if (tb[TCA_POLICE_AVRATE] &&
(ret == ACT_P_CREATED ||
!gen_estimator_active(&police->tcf_bstats,
&police->tcf_rate_est))) {
err = -EINVAL;
goto failure_unlock;
}
/* No failure allowed after this point */
if (R_tab != NULL) {
qdisc_put_rtab(police->tcfp_R_tab);
police->tcfp_R_tab = R_tab;
}
if (P_tab != NULL) {
qdisc_put_rtab(police->tcfp_P_tab);
police->tcfp_P_tab = P_tab;
}
if (tb[TCA_POLICE_RESULT])
police->tcfp_result = nla_get_u32(tb[TCA_POLICE_RESULT]);
police->tcfp_toks = police->tcfp_burst = parm->burst;
police->tcfp_mtu = parm->mtu;
if (police->tcfp_mtu == 0) {
police->tcfp_mtu = ~0;
if (police->tcfp_R_tab)
police->tcfp_mtu = 255<<police->tcfp_R_tab->rate.cell_log;
}
if (police->tcfp_P_tab)
police->tcfp_ptoks = L2T_P(police, police->tcfp_mtu);
police->tcf_action = parm->action;
if (tb[TCA_POLICE_AVRATE])
police->tcfp_ewma_rate = nla_get_u32(tb[TCA_POLICE_AVRATE]);
spin_unlock_bh(&police->tcf_lock);
if (ret != ACT_P_CREATED)
return ret;
police->tcfp_t_c = psched_get_time();
police->tcf_index = parm->index ? parm->index :
tcf_hash_new_index(&police_idx_gen, &police_hash_info);
h = tcf_hash(police->tcf_index, POL_TAB_MASK);
write_lock_bh(&police_lock);
police->tcf_next = tcf_police_ht[h];
tcf_police_ht[h] = &police->common;
write_unlock_bh(&police_lock);
a->priv = police;
return ret;
failure_unlock:
spin_unlock_bh(&police->tcf_lock);
failure:
if (P_tab)
qdisc_put_rtab(P_tab);
if (R_tab)
qdisc_put_rtab(R_tab);
if (ret == ACT_P_CREATED)
kfree(police);
return err;
}
static int tcf_act_police_cleanup(struct tc_action *a, int bind)
{
struct tcf_police *p = a->priv;
int ret = 0;
if (p != NULL) {
if (bind)
p->tcf_bindcnt--;
p->tcf_refcnt--;
if (p->tcf_refcnt <= 0 && !p->tcf_bindcnt) {
tcf_police_destroy(p);
ret = 1;
}
}
return ret;
}
static int tcf_act_police(struct sk_buff *skb, struct tc_action *a,
struct tcf_result *res)
{
struct tcf_police *police = a->priv;
psched_time_t now;
long toks;
long ptoks = 0;
spin_lock(&police->tcf_lock);
police->tcf_bstats.bytes += qdisc_pkt_len(skb);
police->tcf_bstats.packets++;
if (police->tcfp_ewma_rate &&
police->tcf_rate_est.bps >= police->tcfp_ewma_rate) {
police->tcf_qstats.overlimits++;
if (police->tcf_action == TC_ACT_SHOT)
police->tcf_qstats.drops++;
spin_unlock(&police->tcf_lock);
return police->tcf_action;
}
if (qdisc_pkt_len(skb) <= police->tcfp_mtu) {
if (police->tcfp_R_tab == NULL) {
spin_unlock(&police->tcf_lock);
return police->tcfp_result;
}
now = psched_get_time();
toks = psched_tdiff_bounded(now, police->tcfp_t_c,
police->tcfp_burst);
if (police->tcfp_P_tab) {
ptoks = toks + police->tcfp_ptoks;
if (ptoks > (long)L2T_P(police, police->tcfp_mtu))
ptoks = (long)L2T_P(police, police->tcfp_mtu);
ptoks -= L2T_P(police, qdisc_pkt_len(skb));
}
toks += police->tcfp_toks;
if (toks > (long)police->tcfp_burst)
toks = police->tcfp_burst;
toks -= L2T(police, qdisc_pkt_len(skb));
if ((toks|ptoks) >= 0) {
police->tcfp_t_c = now;
police->tcfp_toks = toks;
police->tcfp_ptoks = ptoks;
spin_unlock(&police->tcf_lock);
return police->tcfp_result;
}
}
police->tcf_qstats.overlimits++;
if (police->tcf_action == TC_ACT_SHOT)
police->tcf_qstats.drops++;
spin_unlock(&police->tcf_lock);
return police->tcf_action;
}
static int
tcf_act_police_dump(struct sk_buff *skb, struct tc_action *a, int bind, int ref)
{
unsigned char *b = skb_tail_pointer(skb);
struct tcf_police *police = a->priv;
struct tc_police opt;
opt.index = police->tcf_index;
opt.action = police->tcf_action;
opt.mtu = police->tcfp_mtu;
opt.burst = police->tcfp_burst;
opt.refcnt = police->tcf_refcnt - ref;
opt.bindcnt = police->tcf_bindcnt - bind;
if (police->tcfp_R_tab)
opt.rate = police->tcfp_R_tab->rate;
else
memset(&opt.rate, 0, sizeof(opt.rate));
if (police->tcfp_P_tab)
opt.peakrate = police->tcfp_P_tab->rate;
else
memset(&opt.peakrate, 0, sizeof(opt.peakrate));
NLA_PUT(skb, TCA_POLICE_TBF, sizeof(opt), &opt);
if (police->tcfp_result)
NLA_PUT_U32(skb, TCA_POLICE_RESULT, police->tcfp_result);
if (police->tcfp_ewma_rate)
NLA_PUT_U32(skb, TCA_POLICE_AVRATE, police->tcfp_ewma_rate);
return skb->len;
nla_put_failure:
nlmsg_trim(skb, b);
return -1;
}
MODULE_AUTHOR("Alexey Kuznetsov");
MODULE_DESCRIPTION("Policing actions");
MODULE_LICENSE("GPL");
static struct tc_action_ops act_police_ops = {
.kind = "police",
.hinfo = &police_hash_info,
.type = TCA_ID_POLICE,
.capab = TCA_CAP_NONE,
.owner = THIS_MODULE,
.act = tcf_act_police,
.dump = tcf_act_police_dump,
.cleanup = tcf_act_police_cleanup,
.lookup = tcf_hash_search,
.init = tcf_act_police_locate,
.walk = tcf_act_police_walker
};
static int __init
police_init_module(void)
{
return tcf_register_action(&act_police_ops);
}
static void __exit
police_cleanup_module(void)
{
tcf_unregister_action(&act_police_ops);
rcu_barrier(); /* Wait for completion of call_rcu()'s (tcf_police_free_rcu) */
}
module_init(police_init_module);
module_exit(police_cleanup_module);