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@xxxxxxxxxxxxx>
---
include/linux/netfilter/nfnetlink.h | 2 -
include/net/netfilter/nf_conntrack_ecache.h | 68 +++++++++++++-----
net/netfilter/nf_conntrack_ecache.c | 101 +++++++++++++++++++++++----
net/netfilter/nf_conntrack_netlink.c | 42 +++++------
net/netfilter/nfnetlink.c | 5 +
5 files changed, 157 insertions(+), 61 deletions(-)
diff --git a/include/linux/netfilter/nfnetlink.h b/include/linux/netfilter/nfnetlink.h
index c600083..2214e51 100644
--- a/include/linux/netfilter/nfnetlink.h
+++ b/include/linux/netfilter/nfnetlink.h
@@ -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);
diff --git a/include/net/netfilter/nf_conntrack_ecache.h b/include/net/netfilter/nf_conntrack_ecache.h
index 2e17a2d..39efacb 100644
--- a/include/net/netfilter/nf_conntrack_ecache.h
+++ b/include/net/netfilter/nf_conntrack_ecache.h
@@ -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 int 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 int 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
diff --git a/net/netfilter/nf_conntrack_ecache.c b/net/netfilter/nf_conntrack_ecache.c
index dee4190..780278b 100644
--- a/net/netfilter/nf_conntrack_ecache.c
+++ b/net/netfilter/nf_conntrack_ecache.c
@@ -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;
+EXPORT_SYMBOL_GPL(nf_conntrack_event_cb);
+
+struct nf_exp_event_notifier *nf_expect_event_cb;
+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 +120,86 @@ 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)
+int nf_conntrack_unregister_notifier(struct nf_ct_event_notifier *new)
{
- return atomic_notifier_chain_unregister(&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 != new) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+ rcu_assign_pointer(nf_conntrack_event_cb, NULL);
+ mutex_unlock(&nf_ct_ecache_mutex);
+ return ret;
+
+out_unlock:
+ mutex_unlock(&nf_ct_ecache_mutex);
+ return ret;
}
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)
+int nf_ct_expect_unregister_notifier(struct nf_exp_event_notifier *new)
{
- return atomic_notifier_chain_unregister(&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 != new) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+ rcu_assign_pointer(nf_expect_event_cb, NULL);
+ mutex_unlock(&nf_ct_ecache_mutex);
+ return ret;
+
+out_unlock:
+ mutex_unlock(&nf_ct_ecache_mutex);
+ return ret;
}
EXPORT_SYMBOL_GPL(nf_ct_expect_unregister_notifier);
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index b1b9e4f..4448b06 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -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 @@ nlmsg_failure:
kfree_skb(skb);
errout:
nfnetlink_set_err(0, group, -ENOBUFS);
- return NOTIFY_DONE;
+ return 0;
}
#endif /* CONFIG_NF_CONNTRACK_EVENTS */
@@ -1507,12 +1505,11 @@ nla_put_failure:
}
#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 @@ nlmsg_failure:
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
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index 9dbd570..92761a9 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -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);
--
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