afs: Stop listxattr() from listing "afs.*" attributes

commit a7889c6320b9200e3fe415238f546db677310fa9 upstream.

afs_listxattr() lists all the available special afs xattrs (i.e. those in
the "afs.*" space), no matter what type of server we're dealing with.  But
OpenAFS servers, for example, cannot deal with some of the extra-capable
attributes that AuriStor (YFS) servers provide.  Unfortunately, the
presence of the afs.yfs.* attributes causes errors[1] for anything that
tries to read them if the server is of the wrong type.

Fix the problem by removing afs_listxattr() so that none of the special
xattrs are listed (AFS doesn't support xattrs).  It does mean, however,
that getfattr won't list them, though they can still be accessed with
getxattr() and setxattr().

This can be tested with something like:

	getfattr -d -m ".*" /afs/example.com/path/to/file

With this change, none of the afs.* attributes should be visible.

Changes:
ver #2:
 - Hide all of the afs.* xattrs, not just the ACL ones.

Fixes: ae46578b963f ("afs: Get YFS ACLs and information through xattrs")
Reported-by: Gaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Gaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003502.html [1]
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003567.html # v1
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003573.html # v2
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

6 files changed, 0 insertions, 28 deletions

diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 9068d5578a26..9dc6f4b1c417 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -69,7 +69,6 @@ const struct inode_operations afs_dir_inode_operations = {
 	.permission	= afs_permission,
 	.getattr	= afs_getattr,
 	.setattr	= afs_setattr,
-	.listxattr	= afs_listxattr,
 };
 
 const struct address_space_operations afs_dir_aops = {
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 85f5adf21aa0..960b64268623 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -43,7 +43,6 @@ const struct inode_operations afs_file_inode_operations = {
 	.getattr	= afs_getattr,
 	.setattr	= afs_setattr,
 	.permission	= afs_permission,
-	.listxattr	= afs_listxattr,
 };
 
 const struct address_space_operations afs_fs_aops = {
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index b0d7b892090d..1d03eb1920ec 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -27,7 +27,6 @@
 
 static const struct inode_operations afs_symlink_inode_operations = {
 	.get_link	= page_get_link,
-	.listxattr	= afs_listxattr,
 };
 
 static noinline void dump_vnode(struct afs_vnode *vnode, struct afs_vnode *parent_vnode)
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 0d150a29e39e..525ef075fcd9 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -1508,7 +1508,6 @@ extern int afs_launder_page(struct page *);
  * xattr.c
  */
 extern const struct xattr_handler *afs_xattr_handlers[];
-extern ssize_t afs_listxattr(struct dentry *, char *, size_t);
 
 /*
  * yfsclient.c
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index 052dab2f5c03..bbb2c210d139 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -32,7 +32,6 @@ const struct inode_operations afs_mntpt_inode_operations = {
 	.lookup		= afs_mntpt_lookup,
 	.readlink	= page_readlink,
 	.getattr	= afs_getattr,
-	.listxattr	= afs_listxattr,
 };
 
 const struct inode_operations afs_autocell_inode_operations = {
diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c
index 945ca5033bc5..6a29337bd562 100644
--- a/fs/afs/xattr.c
+++ b/fs/afs/xattr.c
@@ -11,29 +11,6 @@
 #include <linux/xattr.h>
 #include "internal.h"
 
-static const char afs_xattr_list[] =
-	"afs.acl\0"
-	"afs.cell\0"
-	"afs.fid\0"
-	"afs.volume\0"
-	"afs.yfs.acl\0"
-	"afs.yfs.acl_inherited\0"
-	"afs.yfs.acl_num_cleaned\0"
-	"afs.yfs.vol_acl";
-
-/*
- * Retrieve a list of the supported xattrs.
- */
-ssize_t afs_listxattr(struct dentry *dentry, char *buffer, size_t size)
-{
-	if (size == 0)
-		return sizeof(afs_xattr_list);
-	if (size < sizeof(afs_xattr_list))
-		return -ERANGE;
-	memcpy(buffer, afs_xattr_list, sizeof(afs_xattr_list));
-	return sizeof(afs_xattr_list);
-}
-
 /*
  * Deal with the result of a successful fetch ACL operation.
  */