fs/sdfat/xattr.c

   1 /*
   2  *  Copyright (C) 2012-2013 Samsung Electronics Co., Ltd.
   3  *
   4  *  This program is free software; you can redistribute it and/or
   5  *  modify it under the terms of the GNU General Public License
   6  *  as published by the Free Software Foundation; either version 2
   7  *  of the License, or (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /************************************************************************/
  19 /*                                                                      */
  20 /*  PROJECT : exFAT & FAT12/16/32 File System                           */
  21 /*  FILE    : xattr.c                                                   */
  22 /*  PURPOSE : sdFAT code for supporting xattr(Extended File Attributes) */
  23 /*                                                                      */
  24 /*----------------------------------------------------------------------*/
  25 /*  NOTES                                                               */
  26 /*                                                                      */
  27 /*                                                                      */
  28 /************************************************************************/
  29
  30 #include <linux/file.h>
  31 #include <linux/fs.h>
  32 #include <linux/xattr.h>
  33 #include <linux/dcache.h>
  34 #include "sdfat.h"
  35
  36 #ifndef CONFIG_SDFAT_VIRTUAL_XATTR_SELINUX_LABEL
  37 #define CONFIG_SDFAT_VIRTUAL_XATTR_SELINUX_LABEL        ("undefined")
  38 #endif
  39
  40 static const char default_xattr[] = CONFIG_SDFAT_VIRTUAL_XATTR_SELINUX_LABEL;
  41
  42 static int can_support(const char *name)
  43 {
  44         if (!name || strcmp(name, "security.selinux"))
  45                 return -1;
  46         return 0;
  47 }
  48
  49 ssize_t sdfat_listxattr(struct dentry *dentry, char *list, size_t size)
  50 {
  51         return 0;
  52 }
  53
  54
  55 /*************************************************************************
  56  * INNER FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY
  57  *************************************************************************/
  58 static int __sdfat_xattr_check_support(const char *name)
  59 {
  60         if (can_support(name))
  61                 return -EOPNOTSUPP;
  62
  63         return 0;
  64 }
  65
  66 ssize_t __sdfat_getxattr(const char *name, void *value, size_t size)
  67 {
  68         if (can_support(name))
  69                 return -EOPNOTSUPP;
  70
  71         if ((size > strlen(default_xattr)+1) && value)
  72                 strcpy(value, default_xattr);
  73
  74         return strlen(default_xattr);
  75 }
  76
  77
  78 /*************************************************************************
  79  * FUNCTIONS WHICH HAS KERNEL VERSION DEPENDENCY
  80  *************************************************************************/
  81 #if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 9, 0)
  82 static int sdfat_xattr_get(const struct xattr_handler *handler,
  83                 struct dentry *dentry, struct inode *inode,
  84                 const char *name, void *buffer, size_t size)
  85 {
  86         return __sdfat_getxattr(name, buffer, size);
  87 }
  88
  89 static int sdfat_xattr_set(const struct xattr_handler *handler,
  90                 struct dentry *dentry, struct inode *inode,
  91                 const char *name, const void *value, size_t size,
  92                 int flags)
  93 {
  94         return __sdfat_xattr_check_support(name);
  95 }
  96
  97 const struct xattr_handler sdfat_xattr_handler = {
  98         .prefix = "",  /* match anything */
  99         .get = sdfat_xattr_get,
 100         .set = sdfat_xattr_set,
 101 };
 102
 103 const struct xattr_handler *sdfat_xattr_handlers[] = {
 104         &sdfat_xattr_handler,
 105         NULL
 106 };
 107
 108 void setup_sdfat_xattr_handler(struct super_block *sb)
 109 {
 110         sb->s_xattr = sdfat_xattr_handlers;
 111 }
 112 #else /* LINUX_VERSION_CODE < KERNEL_VERSION(4, 9, 0) */
 113 int sdfat_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags)
 114 {
 115         return __sdfat_xattr_check_support(name);
 116 }
 117
 118 ssize_t sdfat_getxattr(struct dentry *dentry, const char *name, void *value, size_t size)
 119 {
 120         return __sdfat_getxattr(name, value, size);
 121 }
 122
 123 int sdfat_removexattr(struct dentry *dentry, const char *name)
 124 {
 125         return __sdfat_xattr_check_support(name);
 126 }
 127
 128 void setup_sdfat_xattr_handler(struct super_block *sb)
 129 {
 130         /* DO NOTHING */
 131 }
 132 #endif