kernel/fs/ext3/acl.c

   1 /*
   2  * linux/fs/ext3/acl.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  */
   6
   7 #include "ext3.h"
   8 #include "xattr.h"
   9 #include "acl.h"
  10
  11 /*
  12  * Convert from filesystem to in-memory representation.
  13  */
  14 static struct posix_acl *
  15 ext3_acl_from_disk(const void *value, size_t size)
  16 {
  17         const char *end = (char *)value + size;
  18         int n, count;
  19         struct posix_acl *acl;
  20
  21         if (!value)
  22                 return NULL;
  23         if (size < sizeof(ext3_acl_header))
  24                  return ERR_PTR(-EINVAL);
  25         if (((ext3_acl_header *)value)->a_version !=
  26             cpu_to_le32(EXT3_ACL_VERSION))
  27                 return ERR_PTR(-EINVAL);
  28         value = (char *)value + sizeof(ext3_acl_header);
  29         count = ext3_acl_count(size);
  30         if (count < 0)
  31                 return ERR_PTR(-EINVAL);
  32         if (count == 0)
  33                 return NULL;
  34         acl = posix_acl_alloc(count, GFP_NOFS);
  35         if (!acl)
  36                 return ERR_PTR(-ENOMEM);
  37         for (n=0; n < count; n++) {
  38                 ext3_acl_entry *entry =
  39                         (ext3_acl_entry *)value;
  40                 if ((char *)value + sizeof(ext3_acl_entry_short) > end)
  41                         goto fail;
  42                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  43                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  44                 switch(acl->a_entries[n].e_tag) {
  45                         case ACL_USER_OBJ:
  46                         case ACL_GROUP_OBJ:
  47                         case ACL_MASK:
  48                         case ACL_OTHER:
  49                                 value = (char *)value +
  50                                         sizeof(ext3_acl_entry_short);
  51                                 break;
  52
  53                         case ACL_USER:
  54                                 value = (char *)value + sizeof(ext3_acl_entry);
  55                                 if ((char *)value > end)
  56                                         goto fail;
  57                                 acl->a_entries[n].e_uid =
  58                                         make_kuid(&init_user_ns,
  59                                                   le32_to_cpu(entry->e_id));
  60                                 break;
  61                         case ACL_GROUP:
  62                                 value = (char *)value + sizeof(ext3_acl_entry);
  63                                 if ((char *)value > end)
  64                                         goto fail;
  65                                 acl->a_entries[n].e_gid =
  66                                         make_kgid(&init_user_ns,
  67                                                   le32_to_cpu(entry->e_id));
  68                                 break;
  69
  70                         default:
  71                                 goto fail;
  72                 }
  73         }
  74         if (value != end)
  75                 goto fail;
  76         return acl;
  77
  78 fail:
  79         posix_acl_release(acl);
  80         return ERR_PTR(-EINVAL);
  81 }
  82
  83 /*
  84  * Convert from in-memory to filesystem representation.
  85  */
  86 static void *
  87 ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
  88 {
  89         ext3_acl_header *ext_acl;
  90         char *e;
  91         size_t n;
  92
  93         *size = ext3_acl_size(acl->a_count);
  94         ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
  95                         sizeof(ext3_acl_entry), GFP_NOFS);
  96         if (!ext_acl)
  97                 return ERR_PTR(-ENOMEM);
  98         ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
  99         e = (char *)ext_acl + sizeof(ext3_acl_header);
 100         for (n=0; n < acl->a_count; n++) {
 101                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 102                 ext3_acl_entry *entry = (ext3_acl_entry *)e;
 103                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 104                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 105                 switch(acl_e->e_tag) {
 106                         case ACL_USER:
 107                                 entry->e_id = cpu_to_le32(
 108                                         from_kuid(&init_user_ns, acl_e->e_uid));
 109                                 e += sizeof(ext3_acl_entry);
 110                                 break;
 111                         case ACL_GROUP:
 112                                 entry->e_id = cpu_to_le32(
 113                                         from_kgid(&init_user_ns, acl_e->e_gid));
 114                                 e += sizeof(ext3_acl_entry);
 115                                 break;
 116
 117                         case ACL_USER_OBJ:
 118                         case ACL_GROUP_OBJ:
 119                         case ACL_MASK:
 120                         case ACL_OTHER:
 121                                 e += sizeof(ext3_acl_entry_short);
 122                                 break;
 123
 124                         default:
 125                                 goto fail;
 126                 }
 127         }
 128         return (char *)ext_acl;
 129
 130 fail:
 131         kfree(ext_acl);
 132         return ERR_PTR(-EINVAL);
 133 }
 134
 135 /*
 136  * Inode operation get_posix_acl().
 137  *
 138  * inode->i_mutex: don't care
 139  */
 140 struct posix_acl *
 141 ext3_get_acl(struct inode *inode, int type)
 142 {
 143         int name_index;
 144         char *value = NULL;
 145         struct posix_acl *acl;
 146         int retval;
 147
 148         switch (type) {
 149         case ACL_TYPE_ACCESS:
 150                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 151                 break;
 152         case ACL_TYPE_DEFAULT:
 153                 name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 154                 break;
 155         default:
 156                 BUG();
 157         }
 158
 159         retval = ext3_xattr_get(inode, name_index, "", NULL, 0);
 160         if (retval > 0) {
 161                 value = kmalloc(retval, GFP_NOFS);
 162                 if (!value)
 163                         return ERR_PTR(-ENOMEM);
 164                 retval = ext3_xattr_get(inode, name_index, "", value, retval);
 165         }
 166         if (retval > 0)
 167                 acl = ext3_acl_from_disk(value, retval);
 168         else if (retval == -ENODATA || retval == -ENOSYS)
 169                 acl = NULL;
 170         else
 171                 acl = ERR_PTR(retval);
 172         kfree(value);
 173
 174         if (!IS_ERR(acl))
 175                 set_cached_acl(inode, type, acl);
 176
 177         return acl;
 178 }
 179
 180 /*
 181  * Set the access or default ACL of an inode.
 182  *
 183  * inode->i_mutex: down unless called from ext3_new_inode
 184  */
 185 static int
 186 __ext3_set_acl(handle_t *handle, struct inode *inode, int type,
 187              struct posix_acl *acl)
 188 {
 189         int name_index;
 190         void *value = NULL;
 191         size_t size = 0;
 192         int error;
 193
 194         switch(type) {
 195                 case ACL_TYPE_ACCESS:
 196                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 197                         if (acl) {
 198                                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 199                                 if (error < 0)
 200                                         return error;
 201                                 else {
 202                                         inode->i_ctime = CURRENT_TIME_SEC;
 203                                         ext3_mark_inode_dirty(handle, inode);
 204                                         if (error == 0)
 205                                                 acl = NULL;
 206                                 }
 207                         }
 208                         break;
 209
 210                 case ACL_TYPE_DEFAULT:
 211                         name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 212                         if (!S_ISDIR(inode->i_mode))
 213                                 return acl ? -EACCES : 0;
 214                         break;
 215
 216                 default:
 217                         return -EINVAL;
 218         }
 219         if (acl) {
 220                 value = ext3_acl_to_disk(acl, &size);
 221                 if (IS_ERR(value))
 222                         return (int)PTR_ERR(value);
 223         }
 224
 225         error = ext3_xattr_set_handle(handle, inode, name_index, "",
 226                                       value, size, 0);
 227
 228         kfree(value);
 229
 230         if (!error)
 231                 set_cached_acl(inode, type, acl);
 232
 233         return error;
 234 }
 235
 236 int
 237 ext3_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 238 {
 239         handle_t *handle;
 240         int error, retries = 0;
 241
 242 retry:
 243         handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 244         if (IS_ERR(handle))
 245                 return PTR_ERR(handle);
 246         error = __ext3_set_acl(handle, inode, type, acl);
 247         ext3_journal_stop(handle);
 248         if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 249                 goto retry;
 250         return error;
 251 }
 252
 253 /*
 254  * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 255  *
 256  * dir->i_mutex: down
 257  * inode->i_mutex: up (access to inode is still exclusive)
 258  */
 259 int
 260 ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 261 {
 262         struct posix_acl *default_acl, *acl;
 263         int error;
 264
 265         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 266         if (error)
 267                 return error;
 268
 269         if (default_acl) {
 270                 error = __ext3_set_acl(handle, inode, ACL_TYPE_DEFAULT,
 271                                        default_acl);
 272                 posix_acl_release(default_acl);
 273         }
 274         if (acl) {
 275                 if (!error)
 276                         error = __ext3_set_acl(handle, inode, ACL_TYPE_ACCESS,
 277                                                acl);
 278                 posix_acl_release(acl);
 279         }
 280         return error;
 281 }