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alistair23-linux/include/net/act_api.h
Davide Caratti ee3bbfe806 net/sched: let actions use RCU to access 'goto_chain' 
use RCU when accessing the action chain, to avoid use after free in the
traffic path when 'goto chain' is replaced on existing TC actions (see
script below). Since the control action is read in the traffic path
without holding the action spinlock, we need to explicitly ensure that
a->goto_chain is not NULL before dereferencing (i.e it's not sufficient
to rely on the value of TC_ACT_GOTO_CHAIN bits). Not doing so caused NULL
dereferences in tcf_action_goto_chain_exec() when the following script:

 # tc chain add dev dd0 chain 42 ingress protocol ip flower \
 > ip_proto udp action pass index 4
 # tc filter add dev dd0 ingress protocol ip flower \
 > ip_proto udp action csum udp goto chain 42 index 66
 # tc chain del dev dd0 chain 42 ingress
 (start UDP traffic towards dd0)
 # tc action replace action csum udp pass index 66

was run repeatedly for several hours.

Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Suggested-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-03-21 13:26:42 -07:00

204 lines
6.4 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __NET_ACT_API_H
#define __NET_ACT_API_H
/*
* Public action API for classifiers/qdiscs
*/
#include <linux/refcount.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
struct tcf_idrinfo {
struct mutex lock;
struct idr action_idr;
};
struct tc_action_ops;
struct tc_action {
const struct tc_action_ops *ops;
__u32 type; /* for backward compat(TCA_OLD_COMPAT) */
__u32 order;
struct tcf_idrinfo *idrinfo;
u32 tcfa_index;
refcount_t tcfa_refcnt;
atomic_t tcfa_bindcnt;
int tcfa_action;
struct tcf_t tcfa_tm;
struct gnet_stats_basic_packed tcfa_bstats;
struct gnet_stats_basic_packed tcfa_bstats_hw;
struct gnet_stats_queue tcfa_qstats;
struct net_rate_estimator __rcu *tcfa_rate_est;
spinlock_t tcfa_lock;
struct gnet_stats_basic_cpu __percpu *cpu_bstats;
struct gnet_stats_basic_cpu __percpu *cpu_bstats_hw;
struct gnet_stats_queue __percpu *cpu_qstats;
struct tc_cookie __rcu *act_cookie;
struct tcf_chain __rcu *goto_chain;
};
#define tcf_index common.tcfa_index
#define tcf_refcnt common.tcfa_refcnt
#define tcf_bindcnt common.tcfa_bindcnt
#define tcf_action common.tcfa_action
#define tcf_tm common.tcfa_tm
#define tcf_bstats common.tcfa_bstats
#define tcf_qstats common.tcfa_qstats
#define tcf_rate_est common.tcfa_rate_est
#define tcf_lock common.tcfa_lock
/* Update lastuse only if needed, to avoid dirtying a cache line.
* We use a temp variable to avoid fetching jiffies twice.
*/
static inline void tcf_lastuse_update(struct tcf_t *tm)
{
unsigned long now = jiffies;
if (tm->lastuse != now)
tm->lastuse = now;
if (unlikely(!tm->firstuse))
tm->firstuse = now;
}
static inline void tcf_tm_dump(struct tcf_t *dtm, const struct tcf_t *stm)
{
dtm->install = jiffies_to_clock_t(jiffies - stm->install);
dtm->lastuse = jiffies_to_clock_t(jiffies - stm->lastuse);
dtm->firstuse = jiffies_to_clock_t(jiffies - stm->firstuse);
dtm->expires = jiffies_to_clock_t(stm->expires);
}
#ifdef CONFIG_NET_CLS_ACT
#define ACT_P_CREATED 1
#define ACT_P_DELETED 1
struct tc_action_ops {
struct list_head head;
char kind[IFNAMSIZ];
enum tca_id id; /* identifier should match kind */
size_t size;
struct module *owner;
int (*act)(struct sk_buff *, const struct tc_action *,
struct tcf_result *); /* called under RCU BH lock*/
int (*dump)(struct sk_buff *, struct tc_action *, int, int);
void (*cleanup)(struct tc_action *);
int (*lookup)(struct net *net, struct tc_action **a, u32 index);
int (*init)(struct net *net, struct nlattr *nla,
struct nlattr *est, struct tc_action **act, int ovr,
int bind, bool rtnl_held, struct tcf_proto *tp,
struct netlink_ext_ack *extack);
int (*walk)(struct net *, struct sk_buff *,
struct netlink_callback *, int,
const struct tc_action_ops *,
struct netlink_ext_ack *);
void (*stats_update)(struct tc_action *, u64, u32, u64, bool);
size_t (*get_fill_size)(const struct tc_action *act);
struct net_device *(*get_dev)(const struct tc_action *a);
void (*put_dev)(struct net_device *dev);
};
struct tc_action_net {
struct tcf_idrinfo *idrinfo;
const struct tc_action_ops *ops;
};
static inline
int tc_action_net_init(struct tc_action_net *tn,
const struct tc_action_ops *ops)
{
int err = 0;
tn->idrinfo = kmalloc(sizeof(*tn->idrinfo), GFP_KERNEL);
if (!tn->idrinfo)
return -ENOMEM;
tn->ops = ops;
mutex_init(&tn->idrinfo->lock);
idr_init(&tn->idrinfo->action_idr);
return err;
}
void tcf_idrinfo_destroy(const struct tc_action_ops *ops,
struct tcf_idrinfo *idrinfo);
static inline void tc_action_net_exit(struct list_head *net_list,
unsigned int id)
{
struct net *net;
rtnl_lock();
list_for_each_entry(net, net_list, exit_list) {
struct tc_action_net *tn = net_generic(net, id);
tcf_idrinfo_destroy(tn->ops, tn->idrinfo);
kfree(tn->idrinfo);
}
rtnl_unlock();
}
int tcf_generic_walker(struct tc_action_net *tn, struct sk_buff *skb,
struct netlink_callback *cb, int type,
const struct tc_action_ops *ops,
struct netlink_ext_ack *extack);
int tcf_idr_search(struct tc_action_net *tn, struct tc_action **a, u32 index);
int tcf_idr_create(struct tc_action_net *tn, u32 index, struct nlattr *est,
struct tc_action **a, const struct tc_action_ops *ops,
int bind, bool cpustats);
void tcf_idr_insert(struct tc_action_net *tn, struct tc_action *a);
void tcf_idr_cleanup(struct tc_action_net *tn, u32 index);
int tcf_idr_check_alloc(struct tc_action_net *tn, u32 *index,
struct tc_action **a, int bind);
int __tcf_idr_release(struct tc_action *a, bool bind, bool strict);
static inline int tcf_idr_release(struct tc_action *a, bool bind)
{
return __tcf_idr_release(a, bind, false);
}
int tcf_register_action(struct tc_action_ops *a, struct pernet_operations *ops);
int tcf_unregister_action(struct tc_action_ops *a,
struct pernet_operations *ops);
int tcf_action_destroy(struct tc_action *actions[], int bind);
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,
bool rtnl_held, struct netlink_ext_ack *extack);
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,
bool rtnl_held,
struct netlink_ext_ack *extack);
int tcf_action_dump(struct sk_buff *skb, struct tc_action *actions[], int bind,
int ref);
int tcf_action_dump_old(struct sk_buff *skb, struct tc_action *a, int, int);
int tcf_action_dump_1(struct sk_buff *skb, struct tc_action *a, int, int);
int tcf_action_copy_stats(struct sk_buff *, struct tc_action *, int);
int tcf_action_check_ctrlact(int action, struct tcf_proto *tp,
struct tcf_chain **handle,
struct netlink_ext_ack *newchain);
struct tcf_chain *tcf_action_set_ctrlact(struct tc_action *a, int action,
struct tcf_chain *newchain);
#endif /* CONFIG_NET_CLS_ACT */
static inline void tcf_action_stats_update(struct tc_action *a, u64 bytes,
u64 packets, u64 lastuse, bool hw)
{
#ifdef CONFIG_NET_CLS_ACT
if (!a->ops->stats_update)
return;
a->ops->stats_update(a, bytes, packets, lastuse, hw);
#endif
}
#endif
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