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netlink: add nlk->netlink_bind hook for module auto-loading

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This patch adds a hook in the binding path of netlink.

This is used by ctnetlink to allow module autoloading for the case
in which one user executes:

 conntrack -E

So far, this resulted in nfnetlink loaded, but not
nf_conntrack_netlink.

I have received in the past many complains on this behaviour.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Pablo Neira Ayuso 2012-06-29 06:15:22 +00:00 committed by David S. Miller
parent a31f2d17b3
commit 03292745b0
3 changed files with 49 additions and 0 deletions
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1
include/linux/netlink.h
View File

@ -179,6 +179,7 @@ struct netlink_kernel_cfg {
unsigned int groups;
void (*input)(struct sk_buff *skb);
struct mutex *cb_mutex;
void (*bind)(int group);
};
extern struct sock *netlink_kernel_create(struct net *net, int unit,

29
net/netfilter/nfnetlink.c
View File

@ -39,6 +39,15 @@ static char __initdata nfversion[] = "0.30";
static const struct nfnetlink_subsystem __rcu *subsys_table[NFNL_SUBSYS_COUNT];
static DEFINE_MUTEX(nfnl_mutex);
static const int nfnl_group2type[NFNLGRP_MAX+1] = {
[NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK,
[NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK,
[NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK,
[NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP,
[NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP,
[NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
};
void nfnl_lock(void)
{
mutex_lock(&nfnl_mutex);
@ -200,12 +209,32 @@ static void nfnetlink_rcv(struct sk_buff *skb)
netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
}
#ifdef CONFIG_MODULES
static void nfnetlink_bind(int group)
{
const struct nfnetlink_subsystem *ss;
int type = nfnl_group2type[group];
rcu_read_lock();
ss = nfnetlink_get_subsys(type);
if (!ss) {
rcu_read_unlock();
request_module("nfnetlink-subsys-%d", type);
return;
}
rcu_read_unlock();
}
#endif
static int __net_init nfnetlink_net_init(struct net *net)
{
struct sock *nfnl;
struct netlink_kernel_cfg cfg = {
.groups = NFNLGRP_MAX,
.input = nfnetlink_rcv,
#ifdef CONFIG_MODULES
.bind = nfnetlink_bind,
#endif
};
nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, THIS_MODULE, &cfg);

19
net/netlink/af_netlink.c
View File

@ -80,6 +80,7 @@ struct netlink_sock {
struct mutex *cb_mutex;
struct mutex cb_def_mutex;
void (*netlink_rcv)(struct sk_buff *skb);
void (*netlink_bind)(int group);
struct module *module;
};
@ -124,6 +125,7 @@ struct netlink_table {
unsigned int groups;
struct mutex *cb_mutex;
struct module *module;
void (*bind)(int group);
int registered;
};
@ -444,6 +446,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
struct module *module = NULL;
struct mutex *cb_mutex;
struct netlink_sock *nlk;
void (*bind)(int group);
int err = 0;
sock->state = SS_UNCONNECTED;
@ -468,6 +471,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
else
err = -EPROTONOSUPPORT;
cb_mutex = nl_table[protocol].cb_mutex;
bind = nl_table[protocol].bind;
netlink_unlock_table();
if (err < 0)
@ -483,6 +487,7 @@ static int netlink_create(struct net *net, struct socket *sock, int protocol,
nlk = nlk_sk(sock->sk);
nlk->module = module;
nlk->netlink_bind = bind;
out:
return err;
@ -683,6 +688,15 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
netlink_update_listeners(sk);
netlink_table_ungrab();
if (nlk->netlink_bind && nlk->groups[0]) {
int i;
for (i=0; i<nlk->ngroups; i++) {
if (test_bit(i, nlk->groups))
nlk->netlink_bind(i);
}
}
return 0;
}
@ -1239,6 +1253,10 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
netlink_update_socket_mc(nlk, val,
optname == NETLINK_ADD_MEMBERSHIP);
netlink_table_ungrab();
if (nlk->netlink_bind)
nlk->netlink_bind(val);
err = 0;
break;
}
@ -1559,6 +1577,7 @@ netlink_kernel_create(struct net *net, int unit,
rcu_assign_pointer(nl_table[unit].listeners, listeners);
nl_table[unit].cb_mutex = cb_mutex;
nl_table[unit].module = module;
nl_table[unit].bind = cfg ? cfg->bind : NULL;
nl_table[unit].registered = 1;
} else {
kfree(listeners);