afs: Lay the groundwork for supporting network namespaces

Lay the groundwork for supporting network namespaces (netns) to the AFS
filesystem by moving various global features to a network-namespace struct
(afs_net) and providing an instance of this as a temporary global variable
that everything uses via accessor functions for the moment.

The following changes have been made:

 (1) Store the netns in the superblock info.  This will be obtained from
     the mounter's nsproxy on a manual mount and inherited from the parent
     superblock on an automount.

 (2) The cell list is made per-netns.  It can be viewed through
     /proc/net/afs/cells and also be modified by writing commands to that
     file.

 (3) The local workstation cell is set per-ns in /proc/net/afs/rootcell.
     This is unset by default.

 (4) The 'rootcell' module parameter, which sets a cell and VL server list
     modifies the init net namespace, thereby allowing an AFS root fs to be
     theoretically used.

 (5) The volume location lists and the file lock manager are made
     per-netns.

 (6) The AF_RXRPC socket and associated I/O bits are made per-ns.

The various workqueues remain global for the moment.

Changes still to be made:

 (1) /proc/fs/afs/ should be moved to /proc/net/afs/ and a symlink emplaced
     from the old name.

 (2) A per-netns subsys needs to be registered for AFS into which it can
     store its per-netns data.

 (3) Rather than the AF_RXRPC socket being opened on module init, it needs
     to be opened on the creation of a superblock in that netns.

 (4) The socket needs to be closed when the last superblock using it is
     destroyed and all outstanding client calls on it have been completed.
     This prevents a reference loop on the namespace.

 (5) It is possible that several namespaces will want to use AFS, in which
     case each one will need its own UDP port.  These can either be set
     through /proc/net/afs/cm_port or the kernel can pick one at random.
     The init_ns gets 7001 by default.

Other issues that need resolving:

 (1) The DNS keyring needs net-namespacing.

 (2) Where do upcalls go (eg. DNS request-key upcall)?

 (3) Need something like open_socket_in_file_ns() syscall so that AFS
     command line tools attempting to operate on an AFS file/volume have
     their RPC calls go to the right place.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 65 insertions, 67 deletions

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 77f5420..656ceb2 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -17,10 +17,7 @@
 #include "internal.h"
 #include "afs_cm.h"
 
-struct socket *afs_socket; /* my RxRPC socket */
-static struct workqueue_struct *afs_async_calls;
-static struct afs_call *afs_spare_incoming_call;
-atomic_t afs_outstanding_calls;
+struct workqueue_struct *afs_async_calls;
 
 static void afs_wake_up_call_waiter(struct sock *, struct rxrpc_call *, unsigned long);
 static int afs_wait_for_call_to_complete(struct afs_call *);
@@ -37,15 +34,11 @@ static const struct afs_call_type afs_RXCMxxxx = {
 	.abort_to_error	= afs_abort_to_error,
 };
 
-static void afs_charge_preallocation(struct work_struct *);
-
-static DECLARE_WORK(afs_charge_preallocation_work, afs_charge_preallocation);
-
 /*
  * open an RxRPC socket and bind it to be a server for callback notifications
  * - the socket is left in blocking mode and non-blocking ops use MSG_DONTWAIT
  */
-int afs_open_socket(void)
+int afs_open_socket(struct afs_net *net)
 {
 	struct sockaddr_rxrpc srx;
 	struct socket *socket;
@@ -53,11 +46,6 @@ int afs_open_socket(void)
 
 	_enter("");
 
-	ret = -ENOMEM;
-	afs_async_calls = alloc_workqueue("kafsd", WQ_MEM_RECLAIM, 0);
-	if (!afs_async_calls)
-		goto error_0;
-
 	ret = sock_create_kern(&init_net, AF_RXRPC, SOCK_DGRAM, PF_INET, &socket);
 	if (ret < 0)
 		goto error_1;
@@ -85,16 +73,14 @@ int afs_open_socket(void)
 	if (ret < 0)
 		goto error_2;
 
-	afs_socket = socket;
-	afs_charge_preallocation(NULL);
+	net->socket = socket;
+	afs_charge_preallocation(&net->charge_preallocation_work);
 	_leave(" = 0");
 	return 0;
 
 error_2:
 	sock_release(socket);
 error_1:
-	destroy_workqueue(afs_async_calls);
-error_0:
 	_leave(" = %d", ret);
 	return ret;
 }
@@ -102,36 +88,36 @@ error_0:
 /*
  * close the RxRPC socket AFS was using
  */
-void afs_close_socket(void)
+void afs_close_socket(struct afs_net *net)
 {
 	_enter("");
 
-	kernel_listen(afs_socket, 0);
+	kernel_listen(net->socket, 0);
 	flush_workqueue(afs_async_calls);
 
-	if (afs_spare_incoming_call) {
-		afs_put_call(afs_spare_incoming_call);
-		afs_spare_incoming_call = NULL;
+	if (net->spare_incoming_call) {
+		afs_put_call(net->spare_incoming_call);
+		net->spare_incoming_call = NULL;
 	}
 
-	_debug("outstanding %u", atomic_read(&afs_outstanding_calls));
-	wait_on_atomic_t(&afs_outstanding_calls, atomic_t_wait,
+	_debug("outstanding %u", atomic_read(&net->nr_outstanding_calls));
+	wait_on_atomic_t(&net->nr_outstanding_calls, atomic_t_wait,
 			 TASK_UNINTERRUPTIBLE);
 	_debug("no outstanding calls");
 
-	kernel_sock_shutdown(afs_socket, SHUT_RDWR);
+	kernel_sock_shutdown(net->socket, SHUT_RDWR);
 	flush_workqueue(afs_async_calls);
-	sock_release(afs_socket);
+	sock_release(net->socket);
 
 	_debug("dework");
-	destroy_workqueue(afs_async_calls);
 	_leave("");
 }
 
 /*
  * Allocate a call.
  */
-static struct afs_call *afs_alloc_call(const struct afs_call_type *type,
+static struct afs_call *afs_alloc_call(struct afs_net *net,
+				       const struct afs_call_type *type,
 				       gfp_t gfp)
 {
 	struct afs_call *call;
@@ -142,11 +128,12 @@ static struct afs_call *afs_alloc_call(const struct afs_call_type *type,
 		return NULL;
 
 	call->type = type;
+	call->net = net;
 	atomic_set(&call->usage, 1);
 	INIT_WORK(&call->async_work, afs_process_async_call);
 	init_waitqueue_head(&call->waitq);
 
-	o = atomic_inc_return(&afs_outstanding_calls);
+	o = atomic_inc_return(&net->nr_outstanding_calls);
 	trace_afs_call(call, afs_call_trace_alloc, 1, o,
 		       __builtin_return_address(0));
 	return call;
@@ -157,8 +144,9 @@ static struct afs_call *afs_alloc_call(const struct afs_call_type *type,
  */
 void afs_put_call(struct afs_call *call)
 {
+	struct afs_net *net = call->net;
 	int n = atomic_dec_return(&call->usage);
-	int o = atomic_read(&afs_outstanding_calls);
+	int o = atomic_read(&net->nr_outstanding_calls);
 
 	trace_afs_call(call, afs_call_trace_put, n + 1, o,
 		       __builtin_return_address(0));
@@ -169,7 +157,7 @@ void afs_put_call(struct afs_call *call)
 		ASSERT(call->type->name != NULL);
 
 		if (call->rxcall) {
-			rxrpc_kernel_end_call(afs_socket, call->rxcall);
+			rxrpc_kernel_end_call(net->socket, call->rxcall);
 			call->rxcall = NULL;
 		}
 		if (call->type->destructor)
@@ -178,11 +166,11 @@ void afs_put_call(struct afs_call *call)
 		kfree(call->request);
 		kfree(call);
 
-		o = atomic_dec_return(&afs_outstanding_calls);
+		o = atomic_dec_return(&net->nr_outstanding_calls);
 		trace_afs_call(call, afs_call_trace_free, 0, o,
 			       __builtin_return_address(0));
 		if (o == 0)
-			wake_up_atomic_t(&afs_outstanding_calls);
+			wake_up_atomic_t(&net->nr_outstanding_calls);
 	}
 }
 
@@ -194,7 +182,7 @@ int afs_queue_call_work(struct afs_call *call)
 	int u = atomic_inc_return(&call->usage);
 
 	trace_afs_call(call, afs_call_trace_work, u,
-		       atomic_read(&afs_outstanding_calls),
+		       atomic_read(&call->net->nr_outstanding_calls),
 		       __builtin_return_address(0));
 
 	INIT_WORK(&call->work, call->type->work);
@@ -207,12 +195,13 @@ int afs_queue_call_work(struct afs_call *call)
 /*
  * allocate a call with flat request and reply buffers
  */
-struct afs_call *afs_alloc_flat_call(const struct afs_call_type *type,
+struct afs_call *afs_alloc_flat_call(struct afs_net *net,
+				     const struct afs_call_type *type,
 				     size_t request_size, size_t reply_max)
 {
 	struct afs_call *call;
 
-	call = afs_alloc_call(type, GFP_NOFS);
+	call = afs_alloc_call(net, type, GFP_NOFS);
 	if (!call)
 		goto nomem_call;
 
@@ -317,7 +306,7 @@ static int afs_send_pages(struct afs_call *call, struct msghdr *msg)
 		bytes = msg->msg_iter.count;
 		nr = msg->msg_iter.nr_segs;
 
-		ret = rxrpc_kernel_send_data(afs_socket, call->rxcall, msg,
+		ret = rxrpc_kernel_send_data(call->net->socket, call->rxcall, msg,
 					     bytes, afs_notify_end_request_tx);
 		for (loop = 0; loop < nr; loop++)
 			put_page(bv[loop].bv_page);
@@ -352,7 +341,7 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 
 	_debug("____MAKE %p{%s,%x} [%d]____",
 	       call, call->type->name, key_serial(call->key),
-	       atomic_read(&afs_outstanding_calls));
+	       atomic_read(&call->net->nr_outstanding_calls));
 
 	call->async = async;
 
@@ -376,7 +365,7 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 	}
 
 	/* create a call */
-	rxcall = rxrpc_kernel_begin_call(afs_socket, &srx, call->key,
+	rxcall = rxrpc_kernel_begin_call(call->net->socket, &srx, call->key,
 					 (unsigned long)call,
 					 tx_total_len, gfp,
 					 (async ?
@@ -410,7 +399,7 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 	 */
 	if (!call->send_pages)
 		call->state = AFS_CALL_AWAIT_REPLY;
-	ret = rxrpc_kernel_send_data(afs_socket, rxcall,
+	ret = rxrpc_kernel_send_data(call->net->socket, rxcall,
 				     &msg, call->request_size,
 				     afs_notify_end_request_tx);
 	if (ret < 0)
@@ -432,13 +421,14 @@ int afs_make_call(struct in_addr *addr, struct afs_call *call, gfp_t gfp,
 error_do_abort:
 	call->state = AFS_CALL_COMPLETE;
 	if (ret != -ECONNABORTED) {
-		rxrpc_kernel_abort_call(afs_socket, rxcall, RX_USER_ABORT,
-					ret, "KSD");
+		rxrpc_kernel_abort_call(call->net->socket, rxcall,
+					RX_USER_ABORT, ret, "KSD");
 	} else {
 		abort_code = 0;
 		offset = 0;
-		rxrpc_kernel_recv_data(afs_socket, rxcall, NULL, 0, &offset,
-				       false, &abort_code, &call->service_id);
+		rxrpc_kernel_recv_data(call->net->socket, rxcall, NULL,
+				       0, &offset, false, &abort_code,
+				       &call->service_id);
 		ret = call->type->abort_to_error(abort_code);
 	}
 error_kill_call:
@@ -464,7 +454,8 @@ static void afs_deliver_to_call(struct afs_call *call)
 	       ) {
 		if (call->state == AFS_CALL_AWAIT_ACK) {
 			size_t offset = 0;
-			ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
+			ret = rxrpc_kernel_recv_data(call->net->socket,
+						     call->rxcall,
 						     NULL, 0, &offset, false,
 						     &call->abort_code,
 						     &call->service_id);
@@ -492,12 +483,12 @@ static void afs_deliver_to_call(struct afs_call *call)
 			goto call_complete;
 		case -ENOTCONN:
 			abort_code = RX_CALL_DEAD;
-			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+			rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
 						abort_code, ret, "KNC");
 			goto save_error;
 		case -ENOTSUPP:
 			abort_code = RXGEN_OPCODE;
-			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+			rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
 						abort_code, ret, "KIV");
 			goto save_error;
 		case -ENODATA:
@@ -507,7 +498,7 @@ static void afs_deliver_to_call(struct afs_call *call)
 			abort_code = RXGEN_CC_UNMARSHAL;
 			if (call->state != AFS_CALL_AWAIT_REPLY)
 				abort_code = RXGEN_SS_UNMARSHAL;
-			rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+			rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
 						abort_code, -EBADMSG, "KUM");
 			goto save_error;
 		}
@@ -541,13 +532,13 @@ static int afs_wait_for_call_to_complete(struct afs_call *call)
 
 	_enter("");
 
-	rtt = rxrpc_kernel_get_rtt(afs_socket, call->rxcall);
+	rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
 	rtt2 = nsecs_to_jiffies64(rtt) * 2;
 	if (rtt2 < 2)
 		rtt2 = 2;
 
 	timeout = rtt2;
-	last_life = rxrpc_kernel_check_life(afs_socket, call->rxcall);
+	last_life = rxrpc_kernel_check_life(call->net->socket, call->rxcall);
 
 	add_wait_queue(&call->waitq, &myself);
 	for (;;) {
@@ -564,7 +555,7 @@ static int afs_wait_for_call_to_complete(struct afs_call *call)
 		if (call->state == AFS_CALL_COMPLETE)
 			break;
 
-		life = rxrpc_kernel_check_life(afs_socket, call->rxcall);
+		life = rxrpc_kernel_check_life(call->net->socket, call->rxcall);
 		if (timeout == 0 &&
 		    life == last_life && signal_pending(current))
 				break;
@@ -583,7 +574,7 @@ static int afs_wait_for_call_to_complete(struct afs_call *call)
 	/* Kill off the call if it's still live. */
 	if (call->state < AFS_CALL_COMPLETE) {
 		_debug("call interrupted");
-		rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+		rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
 					RX_USER_ABORT, -EINTR, "KWI");
 	}
 
@@ -621,7 +612,7 @@ static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
 	u = __atomic_add_unless(&call->usage, 1, 0);
 	if (u != 0) {
 		trace_afs_call(call, afs_call_trace_wake, u,
-			       atomic_read(&afs_outstanding_calls),
+			       atomic_read(&call->net->nr_outstanding_calls),
 			       __builtin_return_address(0));
 
 		if (!queue_work(afs_async_calls, &call->async_work))
@@ -685,13 +676,15 @@ static void afs_rx_attach(struct rxrpc_call *rxcall, unsigned long user_call_ID)
 /*
  * Charge the incoming call preallocation.
  */
-static void afs_charge_preallocation(struct work_struct *work)
+void afs_charge_preallocation(struct work_struct *work)
 {
-	struct afs_call *call = afs_spare_incoming_call;
+	struct afs_net *net =
+		container_of(work, struct afs_net, charge_preallocation_work);
+	struct afs_call *call = net->spare_incoming_call;
 
 	for (;;) {
 		if (!call) {
-			call = afs_alloc_call(&afs_RXCMxxxx, GFP_KERNEL);
+			call = afs_alloc_call(net, &afs_RXCMxxxx, GFP_KERNEL);
 			if (!call)
 				break;
 
@@ -700,7 +693,7 @@ static void afs_charge_preallocation(struct work_struct *work)
 			init_waitqueue_head(&call->waitq);
 		}
 
-		if (rxrpc_kernel_charge_accept(afs_socket,
+		if (rxrpc_kernel_charge_accept(net->socket,
 					       afs_wake_up_async_call,
 					       afs_rx_attach,
 					       (unsigned long)call,
@@ -708,7 +701,7 @@ static void afs_charge_preallocation(struct work_struct *work)
 			break;
 		call = NULL;
 	}
-	afs_spare_incoming_call = call;
+	net->spare_incoming_call = call;
 }
 
 /*
@@ -729,7 +722,9 @@ static void afs_rx_discard_new_call(struct rxrpc_call *rxcall,
 static void afs_rx_new_call(struct sock *sk, struct rxrpc_call *rxcall,
 			    unsigned long user_call_ID)
 {
-	queue_work(afs_wq, &afs_charge_preallocation_work);
+	struct afs_net *net = afs_sock2net(sk);
+
+	queue_work(afs_wq, &net->charge_preallocation_work);
 }
 
 /*
@@ -784,11 +779,12 @@ static void afs_notify_end_reply_tx(struct sock *sock,
  */
 void afs_send_empty_reply(struct afs_call *call)
 {
+	struct afs_net *net = call->net;
 	struct msghdr msg;
 
 	_enter("");
 
-	rxrpc_kernel_set_tx_length(afs_socket, call->rxcall, 0);
+	rxrpc_kernel_set_tx_length(net->socket, call->rxcall, 0);
 
 	msg.msg_name		= NULL;
 	msg.msg_namelen		= 0;
@@ -798,7 +794,7 @@ void afs_send_empty_reply(struct afs_call *call)
 	msg.msg_flags		= 0;
 
 	call->state = AFS_CALL_AWAIT_ACK;
-	switch (rxrpc_kernel_send_data(afs_socket, call->rxcall, &msg, 0,
+	switch (rxrpc_kernel_send_data(net->socket, call->rxcall, &msg, 0,
 				       afs_notify_end_reply_tx)) {
 	case 0:
 		_leave(" [replied]");
@@ -806,7 +802,7 @@ void afs_send_empty_reply(struct afs_call *call)
 
 	case -ENOMEM:
 		_debug("oom");
-		rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+		rxrpc_kernel_abort_call(net->socket, call->rxcall,
 					RX_USER_ABORT, -ENOMEM, "KOO");
 	default:
 		_leave(" [error]");
@@ -819,13 +815,14 @@ void afs_send_empty_reply(struct afs_call *call)
  */
 void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
 {
+	struct afs_net *net = call->net;
 	struct msghdr msg;
 	struct kvec iov[1];
 	int n;
 
 	_enter("");
 
-	rxrpc_kernel_set_tx_length(afs_socket, call->rxcall, len);
+	rxrpc_kernel_set_tx_length(net->socket, call->rxcall, len);
 
 	iov[0].iov_base		= (void *) buf;
 	iov[0].iov_len		= len;
@@ -837,7 +834,7 @@ void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
 	msg.msg_flags		= 0;
 
 	call->state = AFS_CALL_AWAIT_ACK;
-	n = rxrpc_kernel_send_data(afs_socket, call->rxcall, &msg, len,
+	n = rxrpc_kernel_send_data(net->socket, call->rxcall, &msg, len,
 				   afs_notify_end_reply_tx);
 	if (n >= 0) {
 		/* Success */
@@ -847,7 +844,7 @@ void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
 
 	if (n == -ENOMEM) {
 		_debug("oom");
-		rxrpc_kernel_abort_call(afs_socket, call->rxcall,
+		rxrpc_kernel_abort_call(net->socket, call->rxcall,
 					RX_USER_ABORT, -ENOMEM, "KOO");
 	}
 	_leave(" [error]");
@@ -859,6 +856,7 @@ void afs_send_simple_reply(struct afs_call *call, const void *buf, size_t len)
 int afs_extract_data(struct afs_call *call, void *buf, size_t count,
 		     bool want_more)
 {
+	struct afs_net *net = call->net;
 	int ret;
 
 	_enter("{%s,%zu},,%zu,%d",
@@ -866,7 +864,7 @@ int afs_extract_data(struct afs_call *call, void *buf, size_t count,
 
 	ASSERTCMP(call->offset, <=, count);
 
-	ret = rxrpc_kernel_recv_data(afs_socket, call->rxcall,
+	ret = rxrpc_kernel_recv_data(net->socket, call->rxcall,
 				     buf, count, &call->offset,
 				     want_more, &call->abort_code,
 				     &call->service_id);