Commit 4c968709 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipmr: RCU conversion of mroute_sk 



Use RCU and RTNL to protect (struct mr_table)->mroute_sk

Readers use RCU, writers use RTNL.

ip_ra_control() already use an RCU grace period before
ip_ra_destroy_rcu(), so we dont need synchronize_rcu() in
mrtsock_destruct()

Signed-off-by: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 55747a0a

net/ipv4/ipmr.c

+49 −42
Original line number Diff line number Diff line
@@ -75,7 +75,7 @@ struct mr_table { 
	struct net		*net;

#endif

	u32			id;

	struct sock		*mroute_sk;

	struct sock __rcu	*mroute_sk;

	struct timer_list	ipmr_expire_timer;

	struct list_head	mfc_unres_queue;

	struct list_head	mfc_cache_array[MFC_LINES];
@@ -867,6 +867,7 @@ static int ipmr_cache_report(struct mr_table *mrt, 
	const int ihl = ip_hdrlen(pkt);

	struct igmphdr *igmp;

	struct igmpmsg *msg;

	struct sock *mroute_sk;

	int ret;



#ifdef CONFIG_IP_PIMSM
@@ -925,7 +926,10 @@ static int ipmr_cache_report(struct mr_table *mrt, 
	skb->transport_header = skb->network_header;

	}



	if (mrt->mroute_sk == NULL) {

	rcu_read_lock();

	mroute_sk = rcu_dereference(mrt->mroute_sk);

	if (mroute_sk == NULL) {

		rcu_read_unlock();

		kfree_skb(skb);

		return -EINVAL;

	}
@@ -933,7 +937,8 @@ static int ipmr_cache_report(struct mr_table *mrt, 
	/*

	 *	Deliver to mrouted

	 */

	ret = sock_queue_rcv_skb(mrt->mroute_sk, skb);

	ret = sock_queue_rcv_skb(mroute_sk, skb);

	rcu_read_unlock();

	if (ret < 0) {

		if (net_ratelimit())

			printk(KERN_WARNING "mroute: pending queue full, dropping entries.\n");
@@ -1164,6 +1169,9 @@ static void mroute_clean_tables(struct mr_table *mrt) 
	}

}



/* called from ip_ra_control(), before an RCU grace period,

 * we dont need to call synchronize_rcu() here

 */

static void mrtsock_destruct(struct sock *sk)

{

	struct net *net = sock_net(sk);
@@ -1171,13 +1179,9 @@ static void mrtsock_destruct(struct sock *sk) 


	rtnl_lock();

	ipmr_for_each_table(mrt, net) {

		if (sk == mrt->mroute_sk) {

		if (sk == rtnl_dereference(mrt->mroute_sk)) {

			IPV4_DEVCONF_ALL(net, MC_FORWARDING)--;



			write_lock_bh(&mrt_lock);

			mrt->mroute_sk = NULL;

			write_unlock_bh(&mrt_lock);



			rcu_assign_pointer(mrt->mroute_sk, NULL);

			mroute_clean_tables(mrt);

		}

	}
@@ -1204,7 +1208,8 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi 
		return -ENOENT;



	if (optname != MRT_INIT) {

		if (sk != mrt->mroute_sk && !capable(CAP_NET_ADMIN))

		if (sk != rcu_dereference_raw(mrt->mroute_sk) &&

		    !capable(CAP_NET_ADMIN))

			return -EACCES;

	}
@@ -1217,23 +1222,20 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi 
			return -ENOPROTOOPT;



		rtnl_lock();

		if (mrt->mroute_sk) {

		if (rtnl_dereference(mrt->mroute_sk)) {

			rtnl_unlock();

			return -EADDRINUSE;

		}



		ret = ip_ra_control(sk, 1, mrtsock_destruct);

		if (ret == 0) {

			write_lock_bh(&mrt_lock);

			mrt->mroute_sk = sk;

			write_unlock_bh(&mrt_lock);



			rcu_assign_pointer(mrt->mroute_sk, sk);

			IPV4_DEVCONF_ALL(net, MC_FORWARDING)++;

		}

		rtnl_unlock();

		return ret;

	case MRT_DONE:

		if (sk != mrt->mroute_sk)

		if (sk != rcu_dereference_raw(mrt->mroute_sk))

			return -EACCES;

		return ip_ra_control(sk, 0, NULL);

	case MRT_ADD_VIF:
@@ -1246,7 +1248,8 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi 
			return -ENFILE;

		rtnl_lock();

		if (optname == MRT_ADD_VIF) {

			ret = vif_add(net, mrt, &vif, sk == mrt->mroute_sk);

			ret = vif_add(net, mrt, &vif,

				      sk == rtnl_dereference(mrt->mroute_sk));

		} else {

			ret = vif_delete(mrt, vif.vifc_vifi, 0, NULL);

		}
@@ -1267,7 +1270,8 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi 
		if (optname == MRT_DEL_MFC)

			ret = ipmr_mfc_delete(mrt, &mfc);

		else

			ret = ipmr_mfc_add(net, mrt, &mfc, sk == mrt->mroute_sk);

			ret = ipmr_mfc_add(net, mrt, &mfc,

					   sk == rtnl_dereference(mrt->mroute_sk));

		rtnl_unlock();

		return ret;

		/*
@@ -1309,14 +1313,16 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, unsi 
			return -EINVAL;

		if (get_user(v, (u32 __user *)optval))

			return -EFAULT;

		if (sk == mrt->mroute_sk)

			return -EBUSY;



		rtnl_lock();

		ret = 0;

		if (sk == rtnl_dereference(mrt->mroute_sk)) {

			ret = -EBUSY;

		} else {

			if (!ipmr_new_table(net, v))

				ret = -ENOMEM;

			raw_sk(sk)->ipmr_table = v;

		}

		rtnl_unlock();

		return ret;

	}
@@ -1713,6 +1719,7 @@ dont_forward: 


/*

 *	Multicast packets for forwarding arrive here

 *	Called with rcu_read_lock();

 */



int ip_mr_input(struct sk_buff *skb)
@@ -1741,19 +1748,19 @@ int ip_mr_input(struct sk_buff *skb) 
				return 0;

		} else if (ip_hdr(skb)->protocol == IPPROTO_IGMP) {

			/* IGMPv1 (and broken IGMPv2 implementations sort of

			       Cisco IOS <= 11.2(8)) do not put router alert

			       option to IGMP packets destined to routable

			       groups. It is very bad, because it means

			       that we can forward NO IGMP messages.

			 * Cisco IOS <= 11.2(8)) do not put router alert

			 * option to IGMP packets destined to routable

			 * groups. It is very bad, because it means

			 * that we can forward NO IGMP messages.

			 */

			    read_lock(&mrt_lock);

			    if (mrt->mroute_sk) {

			struct sock *mroute_sk;



			mroute_sk = rcu_dereference(mrt->mroute_sk);

			if (mroute_sk) {

				nf_reset(skb);

				    raw_rcv(mrt->mroute_sk, skb);

				    read_unlock(&mrt_lock);

				raw_rcv(mroute_sk, skb);

				return 0;

			}

			    read_unlock(&mrt_lock);

		    }

	}

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