Subject: [RFC 3/4] net: pppol2tp - introduce net-namespace functionality

From: Cyrill Gorcunov <[email-masked]>
Date: Fri, 09 Jan 2009 22:51:57 +0300

- Each tunnel and appropriate lock are inside own namespace now.
- pppox code allows to create per-namespace sockets for
  both PX_PROTO_OE and PX_PROTO_OL2TP protocols. Actually since
  now pppox_create support net-namespaces new PPPo... protocols
  (if they ever will be) should support net-namespace too otherwise
  explicit check for &init_net would be needed.

CC: James Chapman <[email-masked]>
Signed-off-by: Cyrill Gorcunov <[email-masked]>
---
 drivers/net/pppol2tp.c |  164 ++++++++++++++++++++++++++++++++++++-------------
 drivers/net/pppox.c    |    4 -
 2 files changed, 121 insertions(+), 47 deletions(-)

Index: linux-2.6.git/drivers/net/pppol2tp.c
===================================================================
--- linux-2.6.git.orig/drivers/net/pppol2tp.c
+++ linux-2.6.git/drivers/net/pppol2tp.c
@@ -90,7 +90,9 @@
 #include <linux/hash.h>
 #include <linux/sort.h>
 #include <linux/proc_fs.h>
+#include <linux/nsproxy.h>
 #include <net/net_namespace.h>
+#include <net/netns/generic.h>
 #include <net/dst.h>
 #include <net/ip.h>
 #include <net/udp.h>
@@ -204,6 +206,7 @@ struct pppol2tp_tunnel
 	struct sock		*sock;		/* Parent socket */
 	struct list_head	list;		/* Keep a list of all open
 						 * prepared sockets */
+	struct net		*pppol2tp_net;	/* the net we belong to */
 
 	atomic_t		ref_count;
 };
@@ -227,8 +230,20 @@ static atomic_t pppol2tp_tunnel_count;
 static atomic_t pppol2tp_session_count;
 static struct ppp_channel_ops pppol2tp_chan_ops = { pppol2tp_xmit , NULL };
 static struct proto_ops pppol2tp_ops;
-static LIST_HEAD(pppol2tp_tunnel_list);
-static DEFINE_RWLOCK(pppol2tp_tunnel_list_lock);
+
+/* per-net private data for this module */
+static unsigned int pppol2tp_net_id;
+struct pppol2tp_net {
+	struct list_head pppol2tp_tunnel_list;
+	rwlock_t pppol2tp_tunnel_list_lock;
+};
+
+static inline struct pppol2tp_net *pppol2tp_pernet(struct net *net)
+{
+	BUG_ON(!net);
+
+	return net_generic(net, pppol2tp_net_id);
+}
 
 /* Helpers to obtain tunnel/session contexts from sockets.
  */
@@ -321,18 +336,19 @@ pppol2tp_session_find(struct pppol2tp_tu
 
 /* Lookup a tunnel by id
  */
-static struct pppol2tp_tunnel *pppol2tp_tunnel_find(u16 tunnel_id)
+static struct pppol2tp_tunnel *pppol2tp_tunnel_find(struct net *net, u16 tunnel_id)
 {
-	struct pppol2tp_tunnel *tunnel = NULL;
+	struct pppol2tp_tunnel *tunnel;
+	struct pppol2tp_net *pn = pppol2tp_pernet(net);
 
-	read_lock_bh(&pppol2tp_tunnel_list_lock);
-	list_for_each_entry(tunnel, &pppol2tp_tunnel_list, list) {
+	read_lock_bh(&pn->pppol2tp_tunnel_list_lock);
+	list_for_each_entry(tunnel, &pn->pppol2tp_tunnel_list, list) {
 		if (tunnel->stats.tunnel_id == tunnel_id) {
-			read_unlock_bh(&pppol2tp_tunnel_list_lock);
+			read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
 			return tunnel;
 		}
 	}
-	read_unlock_bh(&pppol2tp_tunnel_list_lock);
+	read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
 
 	return NULL;
 }
@@ -1287,10 +1303,12 @@ again:
  */
 static void pppol2tp_tunnel_free(struct pppol2tp_tunnel *tunnel)
 {
+	struct pppol2tp_net *pn = pppol2tp_pernet(tunnel->pppol2tp_net);
+
 	/* Remove from socket list */
-	write_lock_bh(&pppol2tp_tunnel_list_lock);
+	write_lock_bh(&pn->pppol2tp_tunnel_list_lock);
 	list_del_init(&tunnel->list);
-	write_unlock_bh(&pppol2tp_tunnel_list_lock);
+	write_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
 
 	atomic_dec(&pppol2tp_tunnel_count);
 	kfree(tunnel);
@@ -1444,13 +1462,14 @@ error:
 /* Internal function to prepare a tunnel (UDP) socket to have PPPoX
  * sockets attached to it.
  */
-static struct sock *pppol2tp_prepare_tunnel_socket(int fd, u16 tunnel_id,
-						   int *error)
+static struct sock *pppol2tp_prepare_tunnel_socket(struct net *net,
+					int fd, u16 tunnel_id, int *error)
 {
 	int err;
 	struct socket *sock = NULL;
 	struct sock *sk;
 	struct pppol2tp_tunnel *tunnel;
+	struct pppol2tp_net *pn;
 	struct sock *ret = NULL;
 
 	/* Get the tunnel UDP socket from the fd, which was opened by
@@ -1524,11 +1543,15 @@ static struct sock *pppol2tp_prepare_tun
 	/* Misc init */
 	rwlock_init(&tunnel->hlist_lock);
 
+	/* The net we belong to */
+	tunnel->pppol2tp_net = net;
+	pn = pppol2tp_pernet(net);
+
 	/* Add tunnel to our list */
 	INIT_LIST_HEAD(&tunnel->list);
-	write_lock_bh(&pppol2tp_tunnel_list_lock);
-	list_add(&tunnel->list, &pppol2tp_tunnel_list);
-	write_unlock_bh(&pppol2tp_tunnel_list_lock);
+	write_lock_bh(&pn->pppol2tp_tunnel_list_lock);
+	list_add(&tunnel->list, &pn->pppol2tp_tunnel_list);
+	write_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
 	atomic_inc(&pppol2tp_tunnel_count);
 
 	/* Bump the reference count. The tunnel context is deleted
@@ -1629,7 +1652,8 @@ static int pppol2tp_connect(struct socke
 	 * tunnel id.
 	 */
 	if ((sp->pppol2tp.s_session == 0) && (sp->pppol2tp.d_session == 0)) {
-		tunnel_sock = pppol2tp_prepare_tunnel_socket(sp->pppol2tp.fd,
+		tunnel_sock = pppol2tp_prepare_tunnel_socket(current->nsproxy->net_ns,
+							     sp->pppol2tp.fd,
 							     sp->pppol2tp.s_tunnel,
 							     &error);
 		if (tunnel_sock == NULL)
@@ -1637,7 +1661,7 @@ static int pppol2tp_connect(struct socke
 
 		tunnel = tunnel_sock->sk_user_data;
 	} else {
-		tunnel = pppol2tp_tunnel_find(sp->pppol2tp.s_tunnel);
+		tunnel = pppol2tp_tunnel_find(current->nsproxy->net_ns, sp->pppol2tp.s_tunnel);
 
 		/* Error if we can't find the tunnel */
 		error = -ENOENT;
@@ -2347,8 +2371,9 @@ end:
 #include <linux/seq_file.h>
 
 struct pppol2tp_seq_data {
-	struct pppol2tp_tunnel *tunnel; /* current tunnel */
-	struct pppol2tp_session *session; /* NULL means get first session in tunnel */
+	struct net *seq_net;			/* net of inode */
+	struct pppol2tp_tunnel *tunnel;		/* current tunnel */
+	struct pppol2tp_session *session;	/* NULL means get first session in tunnel */
 };
 
 static struct pppol2tp_session *next_session(struct pppol2tp_tunnel *tunnel, struct pppol2tp_session *curr)
@@ -2384,17 +2409,18 @@ out:
 	return session;
 }
 
-static struct pppol2tp_tunnel *next_tunnel(struct pppol2tp_tunnel *curr)
+static struct pppol2tp_tunnel *next_tunnel(struct pppol2tp_net *pn,
+					   struct pppol2tp_tunnel *curr)
 {
 	struct pppol2tp_tunnel *tunnel = NULL;
 
-	read_lock_bh(&pppol2tp_tunnel_list_lock);
-	if (list_is_last(&curr->list, &pppol2tp_tunnel_list)) {
+	read_lock_bh(&pn->pppol2tp_tunnel_list_lock);
+	if (list_is_last(&curr->list, &pn->pppol2tp_tunnel_list)) {
 		goto out;
 	}
 	tunnel = list_entry(curr->list.next, struct pppol2tp_tunnel, list);
 out:
-	read_unlock_bh(&pppol2tp_tunnel_list_lock);
+	read_unlock_bh(&pn->pppol2tp_tunnel_list_lock);
 
 	return tunnel;
 }
@@ -2402,6 +2428,7 @@ out:
 static void *pppol2tp_seq_start(struct seq_file *m, loff_t *offs)
 {
 	struct pppol2tp_seq_data *pd = SEQ_START_TOKEN;
+	struct pppol2tp_net *pn;
 	loff_t pos = *offs;
 
 	if (!pos)
@@ -2409,14 +2436,15 @@ static void *pppol2tp_seq_start(struct s
 
 	BUG_ON(m->private == NULL);
 	pd = m->private;
+	pn = pppol2tp_pernet(pd->seq_net);
 
 	if (pd->tunnel == NULL) {
-		if (!list_empty(&pppol2tp_tunnel_list))
-			pd->tunnel = list_entry(pppol2tp_tunnel_list.next, struct pppol2tp_tunnel, list);
+		if (!list_empty(&pn->pppol2tp_tunnel_list))
+			pd->tunnel = list_entry(pn->pppol2tp_tunnel_list.next, struct pppol2tp_tunnel, list);
 	} else {
 		pd->session = next_session(pd->tunnel, pd->session);
 		if (pd->session == NULL) {
-			pd->tunnel = next_tunnel(pd->tunnel);
+			pd->tunnel = next_tunnel(pn, pd->tunnel);
 		}
 	}
 
@@ -2532,6 +2560,7 @@ static int pppol2tp_proc_open(struct ino
 {
 	struct seq_file *m;
 	struct pppol2tp_seq_data *pd;
+	struct net *net;
 	int ret = 0;
 
 	ret = seq_open(file, &pppol2tp_seq_ops);
@@ -2542,12 +2571,15 @@ static int pppol2tp_proc_open(struct ino
 
 	/* Allocate and fill our proc_data for access later */
 	ret = -ENOMEM;
-	m->private = kzalloc(sizeof(struct pppol2tp_seq_data), GFP_KERNEL);
+	m->private = kzalloc(sizeof(*pd), GFP_KERNEL);
 	if (m->private == NULL)
 		goto out;
 
 	pd = m->private;
-	ret = 0;
+	net = maybe_get_net(PDE_NET(PDE(inode)));
+	BUG_ON(!net);
+	pd->seq_net = net;
+	return 0;
 
 out:
 	return ret;
@@ -2558,6 +2590,9 @@ out:
 static int pppol2tp_proc_release(struct inode *inode, struct file *file)
 {
 	struct seq_file *m = (struct seq_file *)file->private_data;
+	struct pppol2tp_seq_data *pd = m->private;
+
+	put_net(pd->seq_net);
 
 	kfree(m->private);
 	m->private = NULL;
@@ -2573,8 +2608,6 @@ static struct file_operations pppol2tp_p
 	.release	= pppol2tp_proc_release,
 };
 
-static struct proc_dir_entry *pppol2tp_proc;
-
 #endif /* CONFIG_PROC_FS */
 
 /*****************************************************************************
@@ -2606,6 +2639,61 @@ static struct pppox_proto pppol2tp_proto
 	.ioctl		= pppol2tp_ioctl
 };
 
+static __net_init int pppol2tp_init_net(struct net *net)
+{
+	struct pppol2tp_net *pn;
+	struct proc_dir_entry *pde;
+	int err;
+
+	pn = kzalloc(sizeof(*pn), GFP_KERNEL);
+	if (!pn)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&pn->pppol2tp_tunnel_list);
+	rwlock_init(&pn->pppol2tp_tunnel_list_lock);
+
+	err = net_assign_generic(net, pppol2tp_net_id, pn);
+	if (err)
+		goto out;
+
+	pde = proc_net_fops_create(net, "pppol2tp", S_IRUGO, &pppol2tp_proc_fops);
+#ifdef CONFIG_PROC_FS
+	if (!pde) {
+		err = -ENOMEM;
+		goto out;
+	}
+#endif
+
+	try_module_get(THIS_MODULE);
+
+	return 0;
+
+out:
+	kfree(pn);
+	return err;
+}
+
+static __net_exit void pppol2tp_exit_net(struct net *net)
+{
+	struct pppoe_net *pn;
+
+	proc_net_remove(net, "pppol2tp");
+	pn = net_generic(net, pppol2tp_net_id);
+	/*
+	 * if someone has cached our net then
+	 * further net_generic call will return NULL
+	 */
+	net_assign_generic(net, pppol2tp_net_id, NULL);
+	kfree(pn);
+
+	module_put(THIS_MODULE);
+}
+
+static __net_initdata struct pernet_operations pppol2tp_net_ops = {
+	.init = pppol2tp_init_net,
+	.exit = pppol2tp_exit_net,
+};
+
 static int __init pppol2tp_init(void)
 {
 	int err;
@@ -2617,23 +2705,17 @@ static int __init pppol2tp_init(void)
 	if (err)
 		goto out_unregister_pppol2tp_proto;
 
-#ifdef CONFIG_PROC_FS
-	pppol2tp_proc = proc_net_fops_create(&init_net, "pppol2tp", 0,
-					     &pppol2tp_proc_fops);
-	if (!pppol2tp_proc) {
-		err = -ENOMEM;
+	err = register_pernet_gen_device(&pppol2tp_net_id, &pppol2tp_net_ops);
+	if (err)
 		goto out_unregister_pppox_proto;
-	}
-#endif /* CONFIG_PROC_FS */
+
 	printk(KERN_INFO "PPPoL2TP kernel driver, %s\n",
 	       PPPOL2TP_DRV_VERSION);
 
 out:
 	return err;
-#ifdef CONFIG_PROC_FS
 out_unregister_pppox_proto:
 	unregister_pppox_proto(PX_PROTO_OL2TP);
-#endif
 out_unregister_pppol2tp_proto:
 	proto_unregister(&pppol2tp_sk_proto);
 	goto out;
@@ -2642,10 +2724,6 @@ out_unregister_pppol2tp_proto:
 static void __exit pppol2tp_exit(void)
 {
 	unregister_pppox_proto(PX_PROTO_OL2TP);
-
-#ifdef CONFIG_PROC_FS
-	remove_proc_entry("pppol2tp", init_net.proc_net);
-#endif
 	proto_unregister(&pppol2tp_sk_proto);
 }
 
Index: linux-2.6.git/drivers/net/pppox.c
===================================================================
--- linux-2.6.git.orig/drivers/net/pppox.c
+++ linux-2.6.git/drivers/net/pppox.c
@@ -111,10 +111,6 @@ static int pppox_create(struct net *net,
 	if (protocol < 0 || protocol > PX_MAX_PROTO)
 		goto out;
 
-	/* we support net-namespaces for PPPoE only (yet) */
-	if (protocol != PX_PROTO_OE && net != &init_net)
-		return -EAFNOSUPPORT;
-
 	rc = -EPROTONOSUPPORT;
 	if (!pppox_protos[protocol])
 		request_module("pppox-proto-%d", protocol);

--