fs/ext2/xattr_user.c

   1 /*
   2  * linux/fs/ext2/xattr_user.c
   3  * Handler for extended user attributes.
   4  *
   5  * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
   6  */
   7
   8 #include <linux/init.h>
   9 #include <linux/module.h>
  10 #include <linux/string.h>
  11 #include "ext2.h"
  12 #include "xattr.h"
  13
  14 #define XATTR_USER_PREFIX "user."
  15
  16 static size_t
  17 ext2_xattr_user_list(char *list, struct inode *inode,
  18                      const char *name, int name_len)
  19 {
  20         const int prefix_len = sizeof(XATTR_USER_PREFIX)-1;
  21
  22         if (!test_opt(inode->i_sb, XATTR_USER))
  23                 return 0;
  24
  25         if (list) {
  26                 memcpy(list, XATTR_USER_PREFIX, prefix_len);
  27                 memcpy(list+prefix_len, name, name_len);
  28                 list[prefix_len + name_len] = '\0';
  29         }
  30         return prefix_len + name_len + 1;
  31 }
  32
  33 static int
  34 ext2_xattr_user_get(struct inode *inode, const char *name,
  35                     void *buffer, size_t size)
  36 {
  37         int error;
  38
  39         if (strcmp(name, "") == 0)
  40                 return -EINVAL;
  41         if (!test_opt(inode->i_sb, XATTR_USER))
  42                 return -EOPNOTSUPP;
  43         error = permission(inode, MAY_READ, NULL);
  44         if (error)
  45                 return error;
  46
  47         return ext2_xattr_get(inode, EXT2_XATTR_INDEX_USER, name, buffer, size);
  48 }
  49
  50 static int
  51 ext2_xattr_user_set(struct inode *inode, const char *name,
  52                     const void *value, size_t size, int flags)
  53 {
  54         int error;
  55
  56         if (strcmp(name, "") == 0)
  57                 return -EINVAL;
  58         if (!test_opt(inode->i_sb, XATTR_USER))
  59                 return -EOPNOTSUPP;
  60         if ( !S_ISREG(inode->i_mode) &&
  61             (!S_ISDIR(inode->i_mode) || inode->i_mode & S_ISVTX))
  62                 return -EPERM;
  63         error = permission(inode, MAY_WRITE, NULL);
  64         if (error)
  65                 return error;
  66
  67         return ext2_xattr_set(inode, EXT2_XATTR_INDEX_USER, name,
  68                               value, size, flags);
  69 }
  70
  71 struct ext2_xattr_handler ext2_xattr_user_handler = {
  72         .prefix = XATTR_USER_PREFIX,
  73         .list   = ext2_xattr_user_list,
  74         .get    = ext2_xattr_user_get,
  75         .set    = ext2_xattr_user_set,
  76 };
  77
  78 int __init
  79 init_ext2_xattr_user(void)
  80 {
  81         return ext2_xattr_register(EXT2_XATTR_INDEX_USER,
  82                                    &ext2_xattr_user_handler);
  83 }
  84
  85 void
  86 exit_ext2_xattr_user(void)
  87 {
  88         ext2_xattr_unregister(EXT2_XATTR_INDEX_USER,
  89                               &ext2_xattr_user_handler);
  90 }