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, 40 insertions, 24 deletions

diff --git a/fs/afs/proc.c b/fs/afs/proc.c
index 35efb9a31dd7..c93433460348 100644
--- a/fs/afs/proc.c
+++ b/fs/afs/proc.c
@@ -17,8 +17,15 @@
 #include <linux/uaccess.h>
 #include "internal.h"
 
-static struct proc_dir_entry *proc_afs;
+static inline struct afs_net *afs_proc2net(struct file *f)
+{
+	return &__afs_net;
+}
 
+static inline struct afs_net *afs_seq2net(struct seq_file *m)
+{
+	return &__afs_net; // TODO: use seq_file_net(m)
+}
 
 static int afs_proc_cells_open(struct inode *inode, struct file *file);
 static void *afs_proc_cells_start(struct seq_file *p, loff_t *pos);
@@ -122,23 +129,23 @@ static const struct file_operations afs_proc_cell_servers_fops = {
 /*
  * initialise the /proc/fs/afs/ directory
  */
-int afs_proc_init(void)
+int afs_proc_init(struct afs_net *net)
 {
 	_enter("");
 
-	proc_afs = proc_mkdir("fs/afs", NULL);
-	if (!proc_afs)
+	net->proc_afs = proc_mkdir("fs/afs", NULL);
+	if (!net->proc_afs)
 		goto error_dir;
 
-	if (!proc_create("cells", 0644, proc_afs, &afs_proc_cells_fops) ||
-	    !proc_create("rootcell", 0644, proc_afs, &afs_proc_rootcell_fops))
+	if (!proc_create("cells", 0644, net->proc_afs, &afs_proc_cells_fops) ||
+	    !proc_create("rootcell", 0644, net->proc_afs, &afs_proc_rootcell_fops))
 		goto error_tree;
 
 	_leave(" = 0");
 	return 0;
 
 error_tree:
-	remove_proc_subtree("fs/afs", NULL);
+	proc_remove(net->proc_afs);
 error_dir:
 	_leave(" = -ENOMEM");
 	return -ENOMEM;
@@ -147,9 +154,10 @@ error_dir:
 /*
  * clean up the /proc/fs/afs/ directory
  */
-void afs_proc_cleanup(void)
+void afs_proc_cleanup(struct afs_net *net)
 {
-	remove_proc_subtree("fs/afs", NULL);
+	proc_remove(net->proc_afs);
+	net->proc_afs = NULL;
 }
 
 /*
@@ -176,25 +184,30 @@ static int afs_proc_cells_open(struct inode *inode, struct file *file)
  */
 static void *afs_proc_cells_start(struct seq_file *m, loff_t *_pos)
 {
-	/* lock the list against modification */
-	down_read(&afs_proc_cells_sem);
-	return seq_list_start_head(&afs_proc_cells, *_pos);
+	struct afs_net *net = afs_seq2net(m);
+
+	down_read(&net->proc_cells_sem);
+	return seq_list_start_head(&net->proc_cells, *_pos);
 }
 
 /*
  * move to next cell in cells list
  */
-static void *afs_proc_cells_next(struct seq_file *p, void *v, loff_t *pos)
+static void *afs_proc_cells_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	return seq_list_next(v, &afs_proc_cells, pos);
+	struct afs_net *net = afs_seq2net(m);
+
+	return seq_list_next(v, &net->proc_cells, pos);
 }
 
 /*
  * clean up after reading from the cells list
  */
-static void afs_proc_cells_stop(struct seq_file *p, void *v)
+static void afs_proc_cells_stop(struct seq_file *m, void *v)
 {
-	up_read(&afs_proc_cells_sem);
+	struct afs_net *net = afs_seq2net(m);
+
+	up_read(&net->proc_cells_sem);
 }
 
 /*
@@ -203,8 +216,9 @@ static void afs_proc_cells_stop(struct seq_file *p, void *v)
 static int afs_proc_cells_show(struct seq_file *m, void *v)
 {
 	struct afs_cell *cell = list_entry(v, struct afs_cell, proc_link);
+	struct afs_net *net = afs_seq2net(m);
 
-	if (v == &afs_proc_cells) {
+	if (v == &net->proc_cells) {
 		/* display header on line 1 */
 		seq_puts(m, "USE NAME\n");
 		return 0;
@@ -223,6 +237,7 @@ static int afs_proc_cells_show(struct seq_file *m, void *v)
 static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
 				    size_t size, loff_t *_pos)
 {
+	struct afs_net *net = afs_proc2net(file);
 	char *kbuf, *name, *args;
 	int ret;
 
@@ -264,7 +279,7 @@ static ssize_t afs_proc_cells_write(struct file *file, const char __user *buf,
 	if (strcmp(kbuf, "add") == 0) {
 		struct afs_cell *cell;
 
-		cell = afs_cell_create(name, strlen(name), args, false);
+		cell = afs_cell_create(net, name, strlen(name), args, false);
 		if (IS_ERR(cell)) {
 			ret = PTR_ERR(cell);
 			goto done;
@@ -303,6 +318,7 @@ static ssize_t afs_proc_rootcell_write(struct file *file,
 				       const char __user *buf,
 				       size_t size, loff_t *_pos)
 {
+	struct afs_net *net = afs_proc2net(file);
 	char *kbuf, *s;
 	int ret;
 
@@ -322,7 +338,7 @@ static ssize_t afs_proc_rootcell_write(struct file *file,
 	/* determine command to perform */
 	_debug("rootcell=%s", kbuf);
 
-	ret = afs_cell_init(kbuf);
+	ret = afs_cell_init(net, kbuf);
 	if (ret >= 0)
 		ret = size;	/* consume everything, always */
 
@@ -334,13 +350,13 @@ static ssize_t afs_proc_rootcell_write(struct file *file,
 /*
  * initialise /proc/fs/afs/<cell>/
  */
-int afs_proc_cell_setup(struct afs_cell *cell)
+int afs_proc_cell_setup(struct afs_net *net, struct afs_cell *cell)
 {
 	struct proc_dir_entry *dir;
 
 	_enter("%p{%s}", cell, cell->name);
 
-	dir = proc_mkdir(cell->name, proc_afs);
+	dir = proc_mkdir(cell->name, net->proc_afs);
 	if (!dir)
 		goto error_dir;
 
@@ -356,7 +372,7 @@ int afs_proc_cell_setup(struct afs_cell *cell)
 	return 0;
 
 error_tree:
-	remove_proc_subtree(cell->name, proc_afs);
+	remove_proc_subtree(cell->name, net->proc_afs);
 error_dir:
 	_leave(" = -ENOMEM");
 	return -ENOMEM;
@@ -365,11 +381,11 @@ error_dir:
 /*
  * remove /proc/fs/afs/<cell>/
  */
-void afs_proc_cell_remove(struct afs_cell *cell)
+void afs_proc_cell_remove(struct afs_net *net, struct afs_cell *cell)
 {
 	_enter("");
 
-	remove_proc_subtree(cell->name, proc_afs);
+	remove_proc_subtree(cell->name, net->proc_afs);
 
 	_leave("");
 }