Commit 03292745 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso Committed by David S. Miller
Browse files

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



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: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a31f2d17

include/linux/netlink.h

+1 −0
Original line number Diff line number Diff line
@@ -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,

net/netfilter/nfnetlink.c

+29 −0
Original line number Diff line number Diff line
@@ -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);

net/netlink/af_netlink.c

+19 −0
Original line number Diff line number Diff line
@@ -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);

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