Date:   Thu,  2 Jul 2020 12:26:35 +1200
From:   Matt Bennett <matt.bennett@...iedtelesis.co.nz>
To:     netdev@...r.kernel.org
Cc:     zbr@...emap.net, ebiederm@...ssion.com,
        linux-kernel@...r.kernel.org,
        Matt Bennett <matt.bennett@...iedtelesis.co.nz>
Subject: [PATCH 5/5] connector: Create connector per namespace

Move to storing the connector instance per network namespace. In doing
so the ability to use the connector functionality outside the default
namespace is now available.

Signed-off-by: Matt Bennett <matt.bennett@...iedtelesis.co.nz>
---
 drivers/connector/cn_proc.c   |  49 ++++++----
 drivers/connector/connector.c | 171 ++++++++++++++++++++++++++++------
 drivers/hv/hv_fcopy.c         |   1 +
 include/linux/connector.h     |  14 ++-
 include/net/net_namespace.h   |   4 +
 kernel/exit.c                 |   2 +-
 6 files changed, 190 insertions(+), 51 deletions(-)

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 9202be177a30..661d921fd146 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -17,6 +17,7 @@
 #include <linux/atomic.h>
 #include <linux/pid_namespace.h>
 #include <net/net_namespace.h>
+#include <linux/netlink.h>
 
 #include <linux/cn_proc.h>
 #include <linux/local_lock.h>
@@ -37,7 +38,6 @@ static inline struct cn_msg *buffer_to_cn_msg(__u8 *buffer)
 	return (struct cn_msg *)(buffer + 4);
 }
 
-static atomic_t proc_event_num_listeners = ATOMIC_INIT(0);
 static struct cb_id cn_proc_event_id = { CN_IDX_PROC, CN_VAL_PROC };
 
 /* local_event.count is used as the sequence number of the netlink message */
@@ -51,6 +51,9 @@ static DEFINE_PER_CPU(struct local_event, local_event) = {
 
 static inline void send_msg(struct cn_msg *msg)
 {
+	int ret = 0;
+	struct net *net = current->nsproxy->net_ns;
+
 	local_lock(&local_event.lock);
 
 	msg->seq = __this_cpu_inc_return(local_event.count) - 1;
@@ -62,7 +65,9 @@ static inline void send_msg(struct cn_msg *msg)
 	 *
 	 * If cn_netlink_send() fails, the data is not sent.
 	 */
-	cn_netlink_send(&init_net, msg, 0, CN_IDX_PROC, GFP_NOWAIT);
+	ret = cn_netlink_send(net, msg, 0, CN_IDX_PROC, GFP_NOWAIT);
+	if (ret == -ESRCH && netlink_has_listeners(net->cdev.nls, CN_IDX_PROC) == 0)
+		atomic_set(&(net->cdev.proc_event_num_listeners), 0);
 
 	local_unlock(&local_event.lock);
 }
@@ -73,8 +78,9 @@ void proc_fork_connector(struct task_struct *task)
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 	struct task_struct *parent;
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -102,8 +108,9 @@ void proc_exec_connector(struct task_struct *task)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -127,8 +134,9 @@ void proc_id_connector(struct task_struct *task, int which_id)
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
 	const struct cred *cred;
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -164,8 +172,9 @@ void proc_sid_connector(struct task_struct *task)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -188,8 +197,9 @@ void proc_ptrace_connector(struct task_struct *task, int ptrace_id)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -220,8 +230,9 @@ void proc_comm_connector(struct task_struct *task)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -246,8 +257,9 @@ void proc_coredump_connector(struct task_struct *task)
 	struct proc_event *ev;
 	struct task_struct *parent;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -279,8 +291,9 @@ void proc_exit_connector(struct task_struct *task)
 	struct proc_event *ev;
 	struct task_struct *parent;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -321,8 +334,9 @@ static void cn_proc_ack(int err, int rcvd_seq, int rcvd_ack)
 	struct cn_msg *msg;
 	struct proc_event *ev;
 	__u8 buffer[CN_PROC_MSG_SIZE] __aligned(8);
+	struct net *net = current->nsproxy->net_ns;
 
-	if (atomic_read(&proc_event_num_listeners) < 1)
+	if (atomic_read(&(net->cdev.proc_event_num_listeners)) < 1)
 		return;
 
 	msg = buffer_to_cn_msg(buffer);
@@ -353,13 +367,10 @@ static void cn_proc_mcast_ctl(struct net *net, struct cn_msg *msg,
 	if (msg->len != sizeof(*mc_op))
 		return;
 
-	/* 
-	 * Events are reported with respect to the initial pid
-	 * and user namespaces so ignore requestors from
-	 * other namespaces.
+	/*
+	 * Events are reported with respect to network namespaces.
 	 */
-	if ((current_user_ns() != &init_user_ns) ||
-	    (task_active_pid_ns(current) != &init_pid_ns))
+	if (current->nsproxy->net_ns != net)
 		return;
 
 	/* Can only change if privileged. */
@@ -371,10 +382,10 @@ static void cn_proc_mcast_ctl(struct net *net, struct cn_msg *msg,
 	mc_op = (enum proc_cn_mcast_op *)msg->data;
 	switch (*mc_op) {
 	case PROC_CN_MCAST_LISTEN:
-		atomic_inc(&proc_event_num_listeners);
+		atomic_inc(&(net->cdev.proc_event_num_listeners));
 		break;
 	case PROC_CN_MCAST_IGNORE:
-		atomic_dec(&proc_event_num_listeners);
+		atomic_dec(&(net->cdev.proc_event_num_listeners));
 		break;
 	default:
 		err = EINVAL;
diff --git a/drivers/connector/connector.c b/drivers/connector/connector.c
index 82fcaa4d8be3..30efcf39751f 100644
--- a/drivers/connector/connector.c
+++ b/drivers/connector/connector.c
@@ -26,9 +26,7 @@ MODULE_AUTHOR("Evgeniy Polyakov <zbr@...emap.net>");
 MODULE_DESCRIPTION("Generic userspace <-> kernelspace connector.");
 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_CONNECTOR);
 
-static struct cn_dev cdev;
-
-static int cn_already_initialized;
+static DEFINE_MUTEX(cn_mutex);
 
 /*
  * Sends mult (multiple) cn_msg at a time.
@@ -66,10 +64,13 @@ int cn_netlink_send_mult(struct net *net, struct cn_msg *msg, u16 len,
 	struct sk_buff *skb;
 	struct nlmsghdr *nlh;
 	struct cn_msg *data;
-	struct cn_dev *dev = &cdev;
+	struct cn_dev *dev = &(net->cdev);
 	u32 group = 0;
 	int found = 0;
 
+	if (!msg || len < 0)
+		return -EINVAL;
+
 	if (portid || __group) {
 		group = __group;
 	} else {
@@ -133,7 +134,7 @@ static int cn_call_callback(struct net *net, struct sk_buff *skb)
 {
 	struct nlmsghdr *nlh;
 	struct cn_callback_entry *i, *cbq = NULL;
-	struct cn_dev *dev = &cdev;
+	struct cn_dev *dev = &net->cdev;
 	struct cn_msg *msg = nlmsg_data(nlmsg_hdr(skb));
 	struct netlink_skb_parms *nsp = &NETLINK_CB(skb);
 	int err = -ENODEV;
@@ -168,7 +169,7 @@ static int cn_call_callback(struct net *net, struct sk_buff *skb)
  *
  * It checks skb, netlink header and msg sizes, and calls callback helper.
  */
-static void cn_rx_skb(struct sk_buff *skb)
+static void __cn_rx_skb(struct sk_buff *skb)
 {
 	struct nlmsghdr *nlh;
 	int len, err;
@@ -190,6 +191,13 @@ static void cn_rx_skb(struct sk_buff *skb)
 	}
 }
 
+static void cn_rx_skb(struct sk_buff *skb)
+{
+	mutex_lock(&cn_mutex);
+	__cn_rx_skb(skb);
+	mutex_unlock(&cn_mutex);
+}
+
 /*
  * Callback add routing - adds callback with given ID and name.
  * If there is registered callback with the same ID it will not be added.
@@ -200,20 +208,47 @@ int cn_add_callback(struct cb_id *id, const char *name,
 		    void (*callback)(struct net *, struct cn_msg *,
 				     struct netlink_skb_parms *))
 {
-	int err;
-	struct cn_dev *dev = &cdev;
-
-	if (!cn_already_initialized)
-		return -EAGAIN;
+	int err = -EINVAL;
+	struct net *net = NULL;
+	struct cn_dev *dev = NULL;
 
-	err = cn_queue_add_callback(dev->cbdev, name, id, callback);
-	if (err)
+	if (!id || !name || !callback)
 		return err;
 
-	return 0;
+	down_read(&net_rwsem);
+	for_each_net(net) {
+		dev = &net->cdev;
+		err = cn_queue_add_callback(dev->cbdev, name, id, callback);
+		if (err)
+			break;
+	}
+
+	if (err) {
+		for_each_net(net) {
+			dev = &net->cdev;
+			cn_queue_del_callback(dev->cbdev, id);
+		}
+	}
+	up_read(&net_rwsem);
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(cn_add_callback);
 
+int cn_add_callback_one(struct net *net, struct cb_id *id, const char *name,
+			void (*callback)(struct net *, struct cn_msg *,
+					 struct netlink_skb_parms *))
+{
+	struct cn_dev *dev = NULL;
+
+	if (!net || !id || !name || !callback)
+		return -EINVAL;
+
+	dev = &(net->cdev);
+	return cn_queue_add_callback(dev->cbdev, name, id, callback);
+}
+EXPORT_SYMBOL_GPL(cn_add_callback_one);
+
 /*
  * Callback remove routing - removes callback
  * with given ID.
@@ -224,15 +259,25 @@ EXPORT_SYMBOL_GPL(cn_add_callback);
  */
 void cn_del_callback(struct cb_id *id)
 {
-	struct cn_dev *dev = &cdev;
+	struct net *net = NULL;
+	struct cn_dev *dev = NULL;
+
+	if (!id)
+		return;
 
-	cn_queue_del_callback(dev->cbdev, id);
+	down_read(&net_rwsem);
+	for_each_net(net) {
+		dev = &net->cdev;
+		cn_queue_del_callback(dev->cbdev, id);
+	}
+	up_read(&net_rwsem);
 }
 EXPORT_SYMBOL_GPL(cn_del_callback);
 
 static int __maybe_unused cn_proc_show(struct seq_file *m, void *v)
 {
-	struct cn_queue_dev *dev = cdev.cbdev;
+	struct net *net = seq_file_single_net(m);
+	struct cn_queue_dev *dev = net->cdev.cbdev;
 	struct cn_callback_entry *cbq;
 
 	seq_printf(m, "Name            ID\n");
@@ -251,15 +296,62 @@ static int __maybe_unused cn_proc_show(struct seq_file *m, void *v)
 	return 0;
 }
 
-static int cn_init(void)
+static int init_cn_net(struct net *net)
+{
+	int ret = 0;
+	struct cn_dev *init_dev = &(init_net.cdev);
+	struct cn_queue_dev *cbdev = init_dev->cbdev;
+
+	struct cn_callback_entry *cbq = NULL;
+	struct cn_callback_entry_ex *cbq_ex = NULL;
+	struct cn_callback_entry_ex *tmp = NULL;
+	LIST_HEAD(head);
+
+	if (!net)
+		return -EINVAL;
+
+	spin_lock_bh(&cbdev->queue_lock);
+	list_for_each_entry(cbq, &cbdev->queue_list, callback_entry) {
+		cbq_ex = kmalloc(sizeof(*cbq_ex), GFP_ATOMIC);
+		if (!cbq_ex) {
+			ret = -ENOMEM;
+			break;
+		}
+		INIT_LIST_HEAD(&(cbq_ex->list));
+
+		memcpy(&cbq_ex->id, &(cbq->id.id), sizeof(struct cb_id));
+		memcpy(cbq_ex->name, &(cbq->id.name), CN_CBQ_NAMELEN);
+		cbq_ex->callback =  cbq->callback;
+
+		list_add_tail(&(cbq_ex->list), &head);
+	}
+	spin_unlock_bh(&cbdev->queue_lock);
+
+	if (ret < 0) {
+		list_for_each_entry_safe(cbq_ex, tmp, &head, list) {
+			kfree(cbq_ex);
+		}
+	} else {
+		list_for_each_entry_safe(cbq_ex, tmp, &head, list) {
+			cn_add_callback_one(net, &(cbq_ex->id), cbq_ex->name,
+					    cbq_ex->callback);
+			kfree(cbq_ex);
+		}
+	}
+
+	return ret;
+}
+
+static int __net_init cn_init(struct net *net)
 {
-	struct cn_dev *dev = &cdev;
+	int ret = 0;
+	struct cn_dev *dev = &net->cdev;
 	struct netlink_kernel_cfg cfg = {
 		.groups	= CN_NETLINK_USERS + 0xf,
 		.input	= cn_rx_skb,
 	};
 
-	dev->nls = netlink_kernel_create(&init_net, NETLINK_CONNECTOR, &cfg);
+	dev->nls = netlink_kernel_create(net, NETLINK_CONNECTOR, &cfg);
 	if (!dev->nls)
 		return -EIO;
 
@@ -268,25 +360,44 @@ static int cn_init(void)
 		netlink_kernel_release(dev->nls);
 		return -EINVAL;
 	}
+	atomic_set(&(dev->proc_event_num_listeners), 0);
 
-	cn_already_initialized = 1;
+	ret = init_cn_net(net);
+	if (ret < 0) {
+		cn_queue_free_dev(dev->cbdev);
+		netlink_kernel_release(dev->nls);
+		return ret;
+	}
 
-	proc_create_single("connector", S_IRUGO, init_net.proc_net, cn_proc_show);
+	proc_create_net_single("connector", 0444, net->proc_net, cn_proc_show,
+			       NULL);
 
 	return 0;
 }
 
-static void cn_fini(void)
+static void __net_exit cn_fini(struct net *net)
 {
-	struct cn_dev *dev = &cdev;
-
-	cn_already_initialized = 0;
-
-	remove_proc_entry("connector", init_net.proc_net);
+	struct cn_dev *dev = &net->cdev;
 
+	remove_proc_entry("connector", net->proc_net);
 	cn_queue_free_dev(dev->cbdev);
 	netlink_kernel_release(dev->nls);
 }
 
-subsys_initcall(cn_init);
-module_exit(cn_fini);
+static struct pernet_operations cn_netlink_net_ops = {
+	.init = cn_init,
+	.exit = cn_fini,
+};
+
+static int __init connector_init(void)
+{
+	return register_pernet_subsys(&cn_netlink_net_ops);
+}
+
+static void __exit connector_exit(void)
+{
+	unregister_pernet_subsys(&cn_netlink_net_ops);
+}
+
+subsys_initcall(connector_init);
+module_exit(connector_exit);
diff --git a/drivers/hv/hv_fcopy.c b/drivers/hv/hv_fcopy.c
index 5040d7e0cd9e..a7151296af5c 100644
--- a/drivers/hv/hv_fcopy.c
+++ b/drivers/hv/hv_fcopy.c
@@ -13,6 +13,7 @@
 #include <linux/workqueue.h>
 #include <linux/hyperv.h>
 #include <linux/sched.h>
+#include <linux/slab.h>
 #include <asm/hyperv-tlfs.h>
 
 #include "hyperv_vmbus.h"
diff --git a/include/linux/connector.h b/include/linux/connector.h
index 8e9385eb18f8..17febd6946ce 100644
--- a/include/linux/connector.h
+++ b/include/linux/connector.h
@@ -14,11 +14,14 @@
 #include <linux/list.h>
 #include <linux/workqueue.h>
 
-#include <net/sock.h>
 #include <uapi/linux/connector.h>
 
 #define CN_CBQ_NAMELEN		32
 
+struct net;
+struct sock;
+struct netlink_skb_parms;
+
 struct cn_queue_dev {
 	atomic_t refcnt;
 	unsigned char name[CN_CBQ_NAMELEN];
@@ -46,11 +49,20 @@ struct cn_callback_entry {
 	u32 seq, group;
 };
 
+struct cn_callback_entry_ex {
+	struct list_head list;
+	struct cb_id id;
+	unsigned char name[CN_CBQ_NAMELEN];
+	void (*callback)(struct net *net, struct cn_msg *cn_msg,
+			 struct netlink_skb_parms *nsp);
+};
+
 struct cn_dev {
 	struct cb_id id;
 
 	u32 seq, groups;
 	struct sock *nls;
+	atomic_t proc_event_num_listeners;
 
 	struct cn_queue_dev *cbdev;
 };
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 2ee5901bec7a..312972fb2dcc 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -38,6 +38,7 @@
 #include <linux/idr.h>
 #include <linux/skbuff.h>
 #include <linux/notifier.h>
+#include <linux/connector.h>
 
 struct user_namespace;
 struct proc_dir_entry;
@@ -187,6 +188,9 @@ struct net {
 #endif
 #if IS_ENABLED(CONFIG_CRYPTO_USER)
 	struct sock		*crypto_nlsk;
+#endif
+#if IS_ENABLED(CONFIG_CONNECTOR)
+	struct cn_dev		cdev;
 #endif
 	struct sock		*diag_nlsk;
 } __randomize_layout;
diff --git a/kernel/exit.c b/kernel/exit.c
index 727150f28103..976fd6032024 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -788,6 +788,7 @@ void __noreturn do_exit(long code)
 
 	tsk->exit_code = code;
 	taskstats_exit(tsk, group_dead);
+	proc_exit_connector(tsk);
 
 	exit_mm();
 
@@ -824,7 +825,6 @@ void __noreturn do_exit(long code)
 
 	exit_tasks_rcu_start();
 	exit_notify(tsk, group_dead);
-	proc_exit_connector(tsk);
 	mpol_put_task_policy(tsk);
 #ifdef CONFIG_FUTEX
 	if (unlikely(current->pi_state_cache))
-- 
2.27.0

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