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netfilter: conntrack: replace notify chain by function pointer 

This patch removes the notify chain infrastructure and replace it
by a simple function pointer. This issue has been mentioned in the
mailing list several times: the use of the notify chain adds
too much overhead for something that is only used by ctnetlink.

This patch also changes nfnetlink_send(). It seems that gfp_any()
returns GFP_KERNEL for user-context request, like those via
ctnetlink, inside the RCU read-side section which is not valid.
Using GFP_KERNEL is also evil since netlink may schedule(),
this leads to "scheduling while atomic" bug reports.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2009-06-03 10:32:06 +02:00 committed by pablo
parent 17e6e4eac0
commit e34d5c1a4f
5 changed files with 139 additions and 61 deletions
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2
include/linux/netfilter/nfnetlink.h
View File

@ -75,7 +75,7 @@ extern int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n);
extern int nfnetlink_has_listeners(unsigned int group);
extern int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group,
int echo);
int echo, gfp_t flags);
extern void nfnetlink_set_err(u32 pid, u32 group, int error);
extern int nfnetlink_unicast(struct sk_buff *skb, u_int32_t pid, int flags);

68
include/net/netfilter/nf_conntrack_ecache.h
View File

@ -6,7 +6,6 @@
#define _NF_CONNTRACK_ECACHE_H
#include <net/netfilter/nf_conntrack.h>
#include <linux/notifier.h>
#include <linux/interrupt.h>
#include <net/net_namespace.h>
#include <net/netfilter/nf_conntrack_expect.h>
@ -69,9 +68,13 @@ struct nf_ct_event {
int report;
};
extern struct atomic_notifier_head nf_conntrack_chain;
extern int nf_conntrack_register_notifier(struct notifier_block *nb);
extern int nf_conntrack_unregister_notifier(struct notifier_block *nb);
struct nf_ct_event_notifier {
int (*fcn)(unsigned int events, struct nf_ct_event *item);
};
extern struct nf_ct_event_notifier *nf_conntrack_event_cb;
extern int nf_conntrack_register_notifier(struct nf_ct_event_notifier *nb);
extern void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *nb);
extern void nf_ct_deliver_cached_events(const struct nf_conn *ct);
extern void __nf_ct_event_cache_init(struct nf_conn *ct);
@ -97,13 +100,23 @@ nf_conntrack_event_report(enum ip_conntrack_events event,
u32 pid,
int report)
{
struct nf_ct_event item = {
.ct = ct,
.pid = pid,
.report = report
};
if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct))
atomic_notifier_call_chain(&nf_conntrack_chain, event, &item);
struct nf_ct_event_notifier *notify;
rcu_read_lock();
notify = rcu_dereference(nf_conntrack_event_cb);
if (notify == NULL)
goto out_unlock;
if (nf_ct_is_confirmed(ct) && !nf_ct_is_dying(ct)) {
struct nf_ct_event item = {
.ct = ct,
.pid = pid,
.report = report
};
notify->fcn(event, &item);
}
out_unlock:
rcu_read_unlock();
}
static inline void
@ -118,9 +131,13 @@ struct nf_exp_event {
int report;
};
extern struct atomic_notifier_head nf_ct_expect_chain;
extern int nf_ct_expect_register_notifier(struct notifier_block *nb);
extern int nf_ct_expect_unregister_notifier(struct notifier_block *nb);
struct nf_exp_event_notifier {
int (*fcn)(unsigned int events, struct nf_exp_event *item);
};
extern struct nf_exp_event_notifier *nf_expect_event_cb;
extern int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *nb);
extern void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *nb);
static inline void
nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
@ -128,12 +145,23 @@ nf_ct_expect_event_report(enum ip_conntrack_expect_events event,
u32 pid,
int report)
{
struct nf_exp_event item = {
.exp = exp,
.pid = pid,
.report = report
};
atomic_notifier_call_chain(&nf_ct_expect_chain, event, &item);
struct nf_exp_event_notifier *notify;
rcu_read_lock();
notify = rcu_dereference(nf_expect_event_cb);
if (notify == NULL)
goto out_unlock;
{
struct nf_exp_event item = {
.exp = exp,
.pid = pid,
.report = report
};
notify->fcn(event, &item);
}
out_unlock:
rcu_read_unlock();
}
static inline void

83
net/netfilter/nf_conntrack_ecache.c
View File

@ -16,24 +16,32 @@
#include <linux/stddef.h>
#include <linux/err.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
ATOMIC_NOTIFIER_HEAD(nf_conntrack_chain);
EXPORT_SYMBOL_GPL(nf_conntrack_chain);
static DEFINE_MUTEX(nf_ct_ecache_mutex);
ATOMIC_NOTIFIER_HEAD(nf_ct_expect_chain);
EXPORT_SYMBOL_GPL(nf_ct_expect_chain);
struct nf_ct_event_notifier *nf_conntrack_event_cb __read_mostly;
EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
struct nf_exp_event_notifier *nf_expect_event_cb __read_mostly;
EXPORT_SYMBOL_GPL(nf_expect_event_cb);
/* deliver cached events and clear cache entry - must be called with locally
* disabled softirqs */
static inline void
__nf_ct_deliver_cached_events(struct nf_conntrack_ecache *ecache)
{
struct nf_ct_event_notifier *notify;
rcu_read_lock();
notify = rcu_dereference(nf_conntrack_event_cb);
if (notify == NULL)
goto out_unlock;
if (nf_ct_is_confirmed(ecache->ct) && !nf_ct_is_dying(ecache->ct)
&& ecache->events) {
struct nf_ct_event item = {
@ -42,14 +50,15 @@ __nf_ct_deliver_cached_events(struct nf_conntrack_ecache *ecache)
.report = 0
};
atomic_notifier_call_chain(&nf_conntrack_chain,
ecache->events,
&item);
notify->fcn(ecache->events, &item);
}
ecache->events = 0;
nf_ct_put(ecache->ct);
ecache->ct = NULL;
out_unlock:
rcu_read_unlock();
}
/* Deliver all cached events for a particular conntrack. This is called
@ -111,26 +120,68 @@ void nf_conntrack_ecache_fini(struct net *net)
free_percpu(net->ct.ecache);
}
int nf_conntrack_register_notifier(struct notifier_block *nb)
int nf_conntrack_register_notifier(struct nf_ct_event_notifier *new)
{
return atomic_notifier_chain_register(&nf_conntrack_chain, nb);
int ret = 0;
struct nf_ct_event_notifier *notify;
mutex_lock(&nf_ct_ecache_mutex);
notify = rcu_dereference(nf_conntrack_event_cb);
if (notify != NULL) {
ret = -EBUSY;
goto out_unlock;
}
rcu_assign_pointer(nf_conntrack_event_cb, new);
mutex_unlock(&nf_ct_ecache_mutex);
return ret;
out_unlock:
mutex_unlock(&nf_ct_ecache_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(nf_conntrack_register_notifier);
int nf_conntrack_unregister_notifier(struct notifier_block *nb)
void nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
{
return atomic_notifier_chain_unregister(&nf_conntrack_chain, nb);
struct nf_ct_event_notifier *notify;
mutex_lock(&nf_ct_ecache_mutex);
notify = rcu_dereference(nf_conntrack_event_cb);
BUG_ON(notify != new);
rcu_assign_pointer(nf_conntrack_event_cb, NULL);
mutex_unlock(&nf_ct_ecache_mutex);
}
EXPORT_SYMBOL_GPL(nf_conntrack_unregister_notifier);
int nf_ct_expect_register_notifier(struct notifier_block *nb)
int nf_ct_expect_register_notifier(struct nf_exp_event_notifier *new)
{
return atomic_notifier_chain_register(&nf_ct_expect_chain, nb);
int ret = 0;
struct nf_exp_event_notifier *notify;
mutex_lock(&nf_ct_ecache_mutex);
notify = rcu_dereference(nf_expect_event_cb);
if (notify != NULL) {
ret = -EBUSY;
goto out_unlock;
}
rcu_assign_pointer(nf_expect_event_cb, new);
mutex_unlock(&nf_ct_ecache_mutex);
return ret;
out_unlock:
mutex_unlock(&nf_ct_ecache_mutex);
return ret;
}
EXPORT_SYMBOL_GPL(nf_ct_expect_register_notifier);
int nf_ct_expect_unregister_notifier(struct notifier_block *nb)
void nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
{
return atomic_notifier_chain_unregister(&nf_ct_expect_chain, nb);
struct nf_exp_event_notifier *notify;
mutex_lock(&nf_ct_ecache_mutex);
notify = rcu_dereference(nf_expect_event_cb);
BUG_ON(notify != new);
rcu_assign_pointer(nf_expect_event_cb, NULL);
mutex_unlock(&nf_ct_ecache_mutex);
}
EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);

42
net/netfilter/nf_conntrack_netlink.c
View File

@ -27,7 +27,6 @@
#include <linux/netlink.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/netfilter.h>
#include <net/netlink.h>
@ -454,13 +453,12 @@ ctnetlink_nlmsg_size(const struct nf_conn *ct)
;
}
static int ctnetlink_conntrack_event(struct notifier_block *this,
unsigned long events, void *ptr)
static int
ctnetlink_conntrack_event(unsigned int events, struct nf_ct_event *item)
{
struct nlmsghdr *nlh;
struct nfgenmsg *nfmsg;
struct nlattr *nest_parms;
struct nf_ct_event *item = (struct nf_ct_event *)ptr;
struct nf_conn *ct = item->ct;
struct sk_buff *skb;
unsigned int type;
@ -468,7 +466,7 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
/* ignore our fake conntrack entry */
if (ct == &nf_conntrack_untracked)
return NOTIFY_DONE;
return 0;
if (events & IPCT_DESTROY) {
type = IPCTNL_MSG_CT_DELETE;
@ -481,10 +479,10 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
type = IPCTNL_MSG_CT_NEW;
group = NFNLGRP_CONNTRACK_UPDATE;
} else
return NOTIFY_DONE;
return 0;
if (!item->report && !nfnetlink_has_listeners(group))
return NOTIFY_DONE;
return 0;
skb = nlmsg_new(ctnetlink_nlmsg_size(ct), GFP_ATOMIC);
if (skb == NULL)
@ -560,8 +558,8 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
rcu_read_unlock();
nlmsg_end(skb, nlh);
nfnetlink_send(skb, item->pid, group, item->report);
return NOTIFY_DONE;
nfnetlink_send(skb, item->pid, group, item->report, GFP_ATOMIC);
return 0;
nla_put_failure:
rcu_read_unlock();
@ -570,7 +568,7 @@ static int ctnetlink_conntrack_event(struct notifier_block *this,
kfree_skb(skb);
errout:
nfnetlink_set_err(0, group, -ENOBUFS);
return NOTIFY_DONE;
return 0;
}
#endif /* CONFIG_NF_CONNTRACK_EVENTS */
@ -1507,12 +1505,11 @@ ctnetlink_exp_fill_info(struct sk_buff *skb, u32 pid, u32 seq,
}
#ifdef CONFIG_NF_CONNTRACK_EVENTS
static int ctnetlink_expect_event(struct notifier_block *this,
unsigned long events, void *ptr)
static int
ctnetlink_expect_event(unsigned int events, struct nf_exp_event *item)
{
struct nlmsghdr *nlh;
struct nfgenmsg *nfmsg;
struct nf_exp_event *item = (struct nf_exp_event *)ptr;
struct nf_conntrack_expect *exp = item->exp;
struct sk_buff *skb;
unsigned int type;
@ -1522,11 +1519,11 @@ static int ctnetlink_expect_event(struct notifier_block *this,
type = IPCTNL_MSG_EXP_NEW;
flags = NLM_F_CREATE|NLM_F_EXCL;
} else
return NOTIFY_DONE;
return 0;
if (!item->report &&
!nfnetlink_has_listeners(NFNLGRP_CONNTRACK_EXP_NEW))
return NOTIFY_DONE;
return 0;
skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
if (skb == NULL)
@ -1548,8 +1545,9 @@ static int ctnetlink_expect_event(struct notifier_block *this,
rcu_read_unlock();
nlmsg_end(skb, nlh);
nfnetlink_send(skb, item->pid, NFNLGRP_CONNTRACK_EXP_NEW, item->report);
return NOTIFY_DONE;
nfnetlink_send(skb, item->pid, NFNLGRP_CONNTRACK_EXP_NEW,
item->report, GFP_ATOMIC);
return 0;
nla_put_failure:
rcu_read_unlock();
@ -1558,7 +1556,7 @@ static int ctnetlink_expect_event(struct notifier_block *this,
kfree_skb(skb);
errout:
nfnetlink_set_err(0, 0, -ENOBUFS);
return NOTIFY_DONE;
return 0;
}
#endif
static int ctnetlink_exp_done(struct netlink_callback *cb)
@ -1864,12 +1862,12 @@ ctnetlink_new_expect(struct sock *ctnl, struct sk_buff *skb,
}
#ifdef CONFIG_NF_CONNTRACK_EVENTS
static struct notifier_block ctnl_notifier = {
.notifier_call = ctnetlink_conntrack_event,
static struct nf_ct_event_notifier ctnl_notifier = {
.fcn = ctnetlink_conntrack_event,
};
static struct notifier_block ctnl_notifier_exp = {
.notifier_call = ctnetlink_expect_event,
static struct nf_exp_event_notifier ctnl_notifier_exp = {
.fcn = ctnetlink_expect_event,
};
#endif

5
net/netfilter/nfnetlink.c
View File

@ -107,9 +107,10 @@ int nfnetlink_has_listeners(unsigned int group)
}
EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
int nfnetlink_send(struct sk_buff *skb, u32 pid, unsigned group, int echo)
int nfnetlink_send(struct sk_buff *skb, u32 pid,
unsigned group, int echo, gfp_t flags)
{
return nlmsg_notify(nfnl, skb, pid, group, echo, gfp_any());
return nlmsg_notify(nfnl, skb, pid, group, echo, flags);
}
EXPORT_SYMBOL_GPL(nfnetlink_send);