fs/xattr_acl.c

   1 /*
   2  * linux/fs/xattr_acl.c
   3  *
   4  * Almost all from linux/fs/ext2/acl.c:
   5  * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@computer.org>
   6  */
   7
   8 #include <linux/export.h>
   9 #include <linux/fs.h>
  10 #include <linux/posix_acl_xattr.h>
  11 #include <linux/gfp.h>
  12
  13
  14 /*
  15  * Convert from extended attribute to in-memory representation.
  16  */
  17 struct posix_acl *
  18 posix_acl_from_xattr(const void *value, size_t size)
  19 {
  20         posix_acl_xattr_header *header = (posix_acl_xattr_header *)value;
  21         posix_acl_xattr_entry *entry = (posix_acl_xattr_entry *)(header+1), *end;
  22         int count;
  23         struct posix_acl *acl;
  24         struct posix_acl_entry *acl_e;
  25
  26         if (!value)
  27                 return NULL;
  28         if (size < sizeof(posix_acl_xattr_header))
  29                  return ERR_PTR(-EINVAL);
  30         if (header->a_version != cpu_to_le32(POSIX_ACL_XATTR_VERSION))
  31                 return ERR_PTR(-EOPNOTSUPP);
  32
  33         count = posix_acl_xattr_count(size);
  34         if (count < 0)
  35                 return ERR_PTR(-EINVAL);
  36         if (count == 0)
  37                 return NULL;
  38
  39         acl = posix_acl_alloc(count, GFP_NOFS);
  40         if (!acl)
  41                 return ERR_PTR(-ENOMEM);
  42         acl_e = acl->a_entries;
  43
  44         for (end = entry + count; entry != end; acl_e++, entry++) {
  45                 acl_e->e_tag  = le16_to_cpu(entry->e_tag);
  46                 acl_e->e_perm = le16_to_cpu(entry->e_perm);
  47
  48                 switch(acl_e->e_tag) {
  49                         case ACL_USER_OBJ:
  50                         case ACL_GROUP_OBJ:
  51                         case ACL_MASK:
  52                         case ACL_OTHER:
  53                                 acl_e->e_id = ACL_UNDEFINED_ID;
  54                                 break;
  55
  56                         case ACL_USER:
  57                         case ACL_GROUP:
  58                                 acl_e->e_id = le32_to_cpu(entry->e_id);
  59                                 break;
  60
  61                         default:
  62                                 goto fail;
  63                 }
  64         }
  65         return acl;
  66
  67 fail:
  68         posix_acl_release(acl);
  69         return ERR_PTR(-EINVAL);
  70 }
  71 EXPORT_SYMBOL (posix_acl_from_xattr);
  72
  73 /*
  74  * Convert from in-memory to extended attribute representation.
  75  */
  76 int
  77 posix_acl_to_xattr(const struct posix_acl *acl, void *buffer, size_t size)
  78 {
  79         posix_acl_xattr_header *ext_acl = (posix_acl_xattr_header *)buffer;
  80         posix_acl_xattr_entry *ext_entry = ext_acl->a_entries;
  81         int real_size, n;
  82
  83         real_size = posix_acl_xattr_size(acl->a_count);
  84         if (!buffer)
  85                 return real_size;
  86         if (real_size > size)
  87                 return -ERANGE;
  88
  89         ext_acl->a_version = cpu_to_le32(POSIX_ACL_XATTR_VERSION);
  90
  91         for (n=0; n < acl->a_count; n++, ext_entry++) {
  92                 ext_entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
  93                 ext_entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
  94                 ext_entry->e_id   = cpu_to_le32(acl->a_entries[n].e_id);
  95         }
  96         return real_size;
  97 }
  98 EXPORT_SYMBOL (posix_acl_to_xattr);