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netfilter: nfnetlink: add mutex per subsystem
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This patch replaces the global lock to one lock per subsystem.
The per-subsystem lock avoids that processes operating
with different subsystems are synchronized.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Pablo Neira Ayuso committed Feb 5, 2013
1 parent 5474f57 commit c14b78e
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Showing 4 changed files with 53 additions and 41 deletions.
4 changes: 2 additions & 2 deletions include/linux/netfilter/nfnetlink.h
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Original file line number Diff line number Diff line change
Expand Up @@ -34,8 +34,8 @@ extern int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, unsigne
extern int nfnetlink_set_err(struct net *net, u32 pid, u32 group, int error);
extern int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u_int32_t pid, int flags);

extern void nfnl_lock(void);
extern void nfnl_unlock(void);
extern void nfnl_lock(__u8 subsys_id);
extern void nfnl_unlock(__u8 subsys_id);

#define MODULE_ALIAS_NFNL_SUBSYS(subsys) \
MODULE_ALIAS("nfnetlink-subsys-" __stringify(subsys))
Expand Down
26 changes: 13 additions & 13 deletions net/netfilter/ipset/ip_set_core.c
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Original file line number Diff line number Diff line change
Expand Up @@ -88,14 +88,14 @@ find_set_type(const char *name, u8 family, u8 revision)
static bool
load_settype(const char *name)
{
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_IPSET);
pr_debug("try to load ip_set_%s\n", name);
if (request_module("ip_set_%s", name) < 0) {
pr_warning("Can't find ip_set type %s\n", name);
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_IPSET);
return false;
}
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_IPSET);
return true;
}

Expand Down Expand Up @@ -532,7 +532,7 @@ ip_set_nfnl_get(const char *name)
ip_set_id_t i, index = IPSET_INVALID_ID;
struct ip_set *s;

nfnl_lock();
nfnl_lock(NFNL_SUBSYS_IPSET);
for (i = 0; i < ip_set_max; i++) {
s = nfnl_set(i);
if (s != NULL && STREQ(s->name, name)) {
Expand All @@ -541,7 +541,7 @@ ip_set_nfnl_get(const char *name)
break;
}
}
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_IPSET);

return index;
}
Expand All @@ -561,13 +561,13 @@ ip_set_nfnl_get_byindex(ip_set_id_t index)
if (index > ip_set_max)
return IPSET_INVALID_ID;

nfnl_lock();
nfnl_lock(NFNL_SUBSYS_IPSET);
set = nfnl_set(index);
if (set)
__ip_set_get(set);
else
index = IPSET_INVALID_ID;
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_IPSET);

return index;
}
Expand All @@ -584,11 +584,11 @@ void
ip_set_nfnl_put(ip_set_id_t index)
{
struct ip_set *set;
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_IPSET);
set = nfnl_set(index);
if (set != NULL)
__ip_set_put(set);
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_IPSET);
}
EXPORT_SYMBOL_GPL(ip_set_nfnl_put);

Expand Down Expand Up @@ -1763,10 +1763,10 @@ ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
goto done;
}
req_get->set.name[IPSET_MAXNAMELEN - 1] = '\0';
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_IPSET);
find_set_and_id(req_get->set.name, &id);
req_get->set.index = id;
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_IPSET);
goto copy;
}
case IP_SET_OP_GET_BYINDEX: {
Expand All @@ -1778,11 +1778,11 @@ ip_set_sockfn_get(struct sock *sk, int optval, void __user *user, int *len)
ret = -EINVAL;
goto done;
}
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_IPSET);
set = nfnl_set(req_get->set.index);
strncpy(req_get->set.name, set ? set->name : "",
IPSET_MAXNAMELEN);
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_IPSET);
goto copy;
}
default:
Expand Down
12 changes: 6 additions & 6 deletions net/netfilter/nf_conntrack_netlink.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1256,13 +1256,13 @@ ctnetlink_parse_nat_setup(struct nf_conn *ct,
if (!parse_nat_setup) {
#ifdef CONFIG_MODULES
rcu_read_unlock();
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
if (request_module("nf-nat") < 0) {
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_CTNETLINK);
rcu_read_lock();
return -EOPNOTSUPP;
}
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_CTNETLINK);
rcu_read_lock();
if (nfnetlink_parse_nat_setup_hook)
return -EAGAIN;
Expand All @@ -1274,13 +1274,13 @@ ctnetlink_parse_nat_setup(struct nf_conn *ct,
if (err == -EAGAIN) {
#ifdef CONFIG_MODULES
rcu_read_unlock();
nfnl_unlock();
nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
if (request_module("nf-nat-%u", nf_ct_l3num(ct)) < 0) {
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_CTNETLINK);
rcu_read_lock();
return -EOPNOTSUPP;
}
nfnl_lock();
nfnl_lock(NFNL_SUBSYS_CTNETLINK);
rcu_read_lock();
#else
err = -EOPNOTSUPP;
Expand Down
52 changes: 32 additions & 20 deletions net/netfilter/nfnetlink.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,10 @@ MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);

static char __initdata nfversion[] = "0.30";

static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT];
static DEFINE_MUTEX(nfnl_mutex);
static struct {
struct mutex mutex;
const struct nfnetlink_subsystem __rcu *subsys;
} table[NFNL_SUBSYS_COUNT];

static const int nfnl_group2type[NFNLGRP_MAX+1] = {
[NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK,
Expand All @@ -48,37 +50,42 @@ static const int nfnl_group2type[NFNLGRP_MAX+1] = {
[NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
};

void nfnl_lock(void)
void nfnl_lock(__u8 subsys_id)
{
mutex_lock(&nfnl_mutex);
mutex_lock(&table[subsys_id].mutex);
}
EXPORT_SYMBOL_GPL(nfnl_lock);

void nfnl_unlock(void)
void nfnl_unlock(__u8 subsys_id)
{
mutex_unlock(&nfnl_mutex);
mutex_unlock(&table[subsys_id].mutex);
}
EXPORT_SYMBOL_GPL(nfnl_unlock);

static struct mutex *nfnl_get_lock(__u8 subsys_id)
{
return &table[subsys_id].mutex;
}

int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
{
nfnl_lock();
if (subsys_table[n->subsys_id]) {
nfnl_unlock();
nfnl_lock(n->subsys_id);
if (table[n->subsys_id].subsys) {
nfnl_unlock(n->subsys_id);
return -EBUSY;
}
rcu_assign_pointer(subsys_table[n->subsys_id], n);
nfnl_unlock();
rcu_assign_pointer(table[n->subsys_id].subsys, n);
nfnl_unlock(n->subsys_id);

return 0;
}
EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);

int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
{
nfnl_lock();
subsys_table[n->subsys_id] = NULL;
nfnl_unlock();
nfnl_lock(n->subsys_id);
table[n->subsys_id].subsys = NULL;
nfnl_unlock(n->subsys_id);
synchronize_rcu();
return 0;
}
Expand All @@ -91,7 +98,7 @@ static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u_int16_t t
if (subsys_id >= NFNL_SUBSYS_COUNT)
return NULL;

return rcu_dereference(subsys_table[subsys_id]);
return rcu_dereference(table[subsys_id].subsys);
}

static inline const struct nfnl_callback *
Expand Down Expand Up @@ -175,6 +182,7 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
struct nlattr *attr = (void *)nlh + min_len;
int attrlen = nlh->nlmsg_len - min_len;
__u8 subsys_id = NFNL_SUBSYS_ID(type);

err = nla_parse(cda, ss->cb[cb_id].attr_count,
attr, attrlen, ss->cb[cb_id].policy);
Expand All @@ -189,18 +197,17 @@ static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
rcu_read_unlock();
} else {
rcu_read_unlock();
nfnl_lock();
if (rcu_dereference_protected(
subsys_table[NFNL_SUBSYS_ID(type)],
lockdep_is_held(&nfnl_mutex)) != ss ||
nfnl_lock(subsys_id);
if (rcu_dereference_protected(table[subsys_id].subsys,
lockdep_is_held(nfnl_get_lock(subsys_id))) != ss ||
nfnetlink_find_client(type, ss) != nc)
err = -EAGAIN;
else if (nc->call)
err = nc->call(net->nfnl, skb, nlh,
(const struct nlattr **)cda);
else
err = -EINVAL;
nfnl_unlock();
nfnl_unlock(subsys_id);
}
if (err == -EAGAIN)
goto replay;
Expand Down Expand Up @@ -267,6 +274,11 @@ static struct pernet_operations nfnetlink_net_ops = {

static int __init nfnetlink_init(void)
{
int i;

for (i=0; i<NFNL_SUBSYS_COUNT; i++)
mutex_init(&table[i].mutex);

pr_info("Netfilter messages via NETLINK v%s.\n", nfversion);
return register_pernet_subsys(&nfnetlink_net_ops);
}
Expand Down

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