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

stable inclusion
from stable-5.10.26
commit 64195f022ae8c24e0abccc1545d557b064e73ed3
bugzilla: 51363

--------------------------------

commit a7889c63 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: ae46578b ("afs: Get YFS ACLs and information through xattrs")
Reported-by: NGaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Tested-by: NGaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Reviewed-by: NJeffrey Altman <jaltman@auristor.com>
Reviewed-by: NMarc 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: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Acked-by: N  Weilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

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 = {

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 = {

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)

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

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 = {

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.
  */