[NETLINK]: Support dynamic number of multicast groups per netlink family

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlink/af_netlink.c

@@ -60,21 +60,24 @@
 #include <net/scm.h>
 
 #define Nprintk(a...)
+#define NLGRPSZ(x)	(ALIGN(x, sizeof(unsigned long) * 8) / 8)
 
 struct netlink_sock {
 	/* struct sock has to be the first member of netlink_sock */
 	struct sock		sk;
 	u32			pid;
-	unsigned int		groups;
 	u32			dst_pid;
 	u32			dst_group;
+	u32			flags;
+	u32			subscriptions;
+	u32			ngroups;
+	unsigned long		*groups;
 	unsigned long		state;
 	wait_queue_head_t	wait;
 	struct netlink_callback	*cb;
 	spinlock_t		cb_lock;
 	void			(*data_ready)(struct sock *sk, int bytes);
 	struct module		*module;
-	u32			flags;
 };
 
 #define NETLINK_KERNEL_SOCKET	0x1
@@ -101,6 +104,7 @@ struct netlink_table {
 	struct nl_pid_hash hash;
 	struct hlist_head mc_list;
 	unsigned int nl_nonroot;
+	unsigned int groups;
 	struct module *module;
 	int registered;
 };
@@ -138,6 +142,7 @@ static void netlink_sock_destruct(struct sock *sk)
 	BUG_TRAP(!atomic_read(&sk->sk_rmem_alloc));
 	BUG_TRAP(!atomic_read(&sk->sk_wmem_alloc));
 	BUG_TRAP(!nlk_sk(sk)->cb);
+	BUG_TRAP(!nlk_sk(sk)->groups);
 }
 
 /* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it is _very_ bad on SMP.
@@ -333,7 +338,7 @@ static void netlink_remove(struct sock *sk)
 	netlink_table_grab();
 	if (sk_del_node_init(sk))
 		nl_table[sk->sk_protocol].hash.entries--;
-	if (nlk_sk(sk)->groups)
+	if (nlk_sk(sk)->subscriptions)
 		__sk_del_bind_node(sk);
 	netlink_table_ungrab();
 }
@@ -369,6 +374,8 @@ static int __netlink_create(struct socket *sock, int protocol)
 static int netlink_create(struct socket *sock, int protocol)
 {
 	struct module *module = NULL;
+	struct netlink_sock *nlk;
+	unsigned int groups;
 	int err = 0;
 
 	sock->state = SS_UNCONNECTED;
@@ -392,15 +399,23 @@ static int netlink_create(struct socket *sock, int protocol)
 		module = nl_table[protocol].module;
 	else
 		err = -EPROTONOSUPPORT;
+	groups = nl_table[protocol].groups;
 	netlink_unlock_table();
 
-	if (err)
-		goto out;
+	if (err || (err = __netlink_create(sock, protocol) < 0))
+		goto out_module;
+
+	nlk = nlk_sk(sock->sk);
 
-	if ((err = __netlink_create(sock, protocol) < 0))
+	nlk->groups = kmalloc(NLGRPSZ(groups), GFP_KERNEL);
+	if (nlk->groups == NULL) {
+		err = -ENOMEM;
 		goto out_module;
+	}
+	memset(nlk->groups, 0, NLGRPSZ(groups));
+	nlk->ngroups = groups;
 
-	nlk_sk(sock->sk)->module = module;
+	nlk->module = module;
 out:
 	return err;
 
@@ -437,7 +452,7 @@ static int netlink_release(struct socket *sock)
 
 	skb_queue_purge(&sk->sk_write_queue);
 
-	if (nlk->pid && !nlk->groups) {
+	if (nlk->pid && !nlk->subscriptions) {
 		struct netlink_notify n = {
 						.protocol = sk->sk_protocol,
 						.pid = nlk->pid,
@@ -455,6 +470,9 @@ static int netlink_release(struct socket *sock)
 		netlink_table_ungrab();
 	}
 
+	kfree(nlk->groups);
+	nlk->groups = NULL;
+
 	sock_put(sk);
 	return 0;
 }
@@ -503,6 +521,18 @@ static inline int netlink_capable(struct socket *sock, unsigned int flag)
 	       capable(CAP_NET_ADMIN);
 } 
 
+static void
+netlink_update_subscriptions(struct sock *sk, unsigned int subscriptions)
+{
+	struct netlink_sock *nlk = nlk_sk(sk);
+
+	if (nlk->subscriptions && !subscriptions)
+		__sk_del_bind_node(sk);
+	else if (!nlk->subscriptions && subscriptions)
+		sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
+	nlk->subscriptions = subscriptions;
+}
+
 static int netlink_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
 {
 	struct sock *sk = sock->sk;
@@ -528,15 +558,14 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, int addr_len
 			return err;
 	}
 
-	if (!nladdr->nl_groups && !nlk->groups)
+	if (!nladdr->nl_groups && !(u32)nlk->groups[0])
 		return 0;
 
 	netlink_table_grab();
-	if (nlk->groups && !nladdr->nl_groups)
-		__sk_del_bind_node(sk);
-	else if (!nlk->groups && nladdr->nl_groups)
-		sk_add_bind_node(sk, &nl_table[sk->sk_protocol].mc_list);
-	nlk->groups = nladdr->nl_groups;
+	netlink_update_subscriptions(sk, nlk->subscriptions +
+	                                 hweight32(nladdr->nl_groups) -
+	                                 hweight32(nlk->groups[0]));
+	nlk->groups[0] = (nlk->groups[0] & ~0xffffffffUL) | nladdr->nl_groups; 
 	netlink_table_ungrab();
 
 	return 0;
@@ -590,7 +619,7 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr, int *addr
 		nladdr->nl_groups = netlink_group_mask(nlk->dst_group);
 	} else {
 		nladdr->nl_pid = nlk->pid;
-		nladdr->nl_groups = nlk->groups; 
+		nladdr->nl_groups = nlk->groups[0];
 	}
 	return 0;
 }
@@ -791,7 +820,8 @@ static inline int do_one_broadcast(struct sock *sk,
 	if (p->exclude_sk == sk)
 		goto out;
 
-	if (nlk->pid == p->pid || !(nlk->groups & netlink_group_mask(p->group)))
+	if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
+	    !test_bit(p->group - 1, nlk->groups))
 		goto out;
 
 	if (p->failure) {
@@ -887,7 +917,8 @@ static inline int do_one_set_err(struct sock *sk,
 	if (sk == p->exclude_sk)
 		goto out;
 
-	if (nlk->pid == p->pid || !(nlk->groups & netlink_group_mask(p->group)))
+	if (nlk->pid == p->pid || p->group - 1 >= nlk->ngroups ||
+	    !test_bit(p->group - 1, nlk->groups))
 		goto out;
 
 	sk->sk_err = p->code;
@@ -1112,6 +1143,7 @@ netlink_kernel_create(int unit, void (*input)(struct sock *sk, int len), struct
 	nlk->flags |= NETLINK_KERNEL_SOCKET;
 
 	netlink_table_grab();
+	nl_table[unit].groups = 32;
 	nl_table[unit].module = module;
 	nl_table[unit].registered = 1;
 	netlink_table_ungrab();
@@ -1358,7 +1390,8 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
 			   s,
 			   s->sk_protocol,
 			   nlk->pid,
-			   nlk->groups,
+			   nlk->flags & NETLINK_KERNEL_SOCKET ?
+				0 : (unsigned int)nlk->groups[0],
 			   atomic_read(&s->sk_rmem_alloc),
 			   atomic_read(&s->sk_wmem_alloc),
 			   nlk->cb,