fs/ext4/acl.c

   1 /*
   2  * linux/fs/ext4/acl.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5  */
   6
   7 #include <linux/quotaops.h>
   8 #include "ext4_jbd2.h"
   9 #include "ext4.h"
  10 #include "xattr.h"
  11 #include "acl.h"
  12
  13 /*
  14  * Convert from filesystem to in-memory representation.
  15  */
  16 static struct posix_acl *
  17 ext4_acl_from_disk(const void *value, size_t size)
  18 {
  19         const char *end = (char *)value + size;
  20         int n, count;
  21         struct posix_acl *acl;
  22
  23         if (!value)
  24                 return NULL;
  25         if (size < sizeof(ext4_acl_header))
  26                  return ERR_PTR(-EINVAL);
  27         if (((ext4_acl_header *)value)->a_version !=
  28             cpu_to_le32(EXT4_ACL_VERSION))
  29                 return ERR_PTR(-EINVAL);
  30         value = (char *)value + sizeof(ext4_acl_header);
  31         count = ext4_acl_count(size);
  32         if (count < 0)
  33                 return ERR_PTR(-EINVAL);
  34         if (count == 0)
  35                 return NULL;
  36         acl = posix_acl_alloc(count, GFP_NOFS);
  37         if (!acl)
  38                 return ERR_PTR(-ENOMEM);
  39         for (n = 0; n < count; n++) {
  40                 ext4_acl_entry *entry =
  41                         (ext4_acl_entry *)value;
  42                 if ((char *)value + sizeof(ext4_acl_entry_short) > end)
  43                         goto fail;
  44                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  45                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  46
  47                 switch (acl->a_entries[n].e_tag) {
  48                 case ACL_USER_OBJ:
  49                 case ACL_GROUP_OBJ:
  50                 case ACL_MASK:
  51                 case ACL_OTHER:
  52                         value = (char *)value +
  53                                 sizeof(ext4_acl_entry_short);
  54                         break;
  55
  56                 case ACL_USER:
  57                         value = (char *)value + sizeof(ext4_acl_entry);
  58                         if ((char *)value > end)
  59                                 goto fail;
  60                         acl->a_entries[n].e_uid =
  61                                 make_kuid(&init_user_ns,
  62                                           le32_to_cpu(entry->e_id));
  63                         break;
  64                 case ACL_GROUP:
  65                         value = (char *)value + sizeof(ext4_acl_entry);
  66                         if ((char *)value > end)
  67                                 goto fail;
  68                         acl->a_entries[n].e_gid =
  69                                 make_kgid(&init_user_ns,
  70                                           le32_to_cpu(entry->e_id));
  71                         break;
  72
  73                 default:
  74                         goto fail;
  75                 }
  76         }
  77         if (value != end)
  78                 goto fail;
  79         return acl;
  80
  81 fail:
  82         posix_acl_release(acl);
  83         return ERR_PTR(-EINVAL);
  84 }
  85
  86 /*
  87  * Convert from in-memory to filesystem representation.
  88  */
  89 static void *
  90 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
  91 {
  92         ext4_acl_header *ext_acl;
  93         char *e;
  94         size_t n;
  95
  96         *size = ext4_acl_size(acl->a_count);
  97         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
  98                         sizeof(ext4_acl_entry), GFP_NOFS);
  99         if (!ext_acl)
 100                 return ERR_PTR(-ENOMEM);
 101         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
 102         e = (char *)ext_acl + sizeof(ext4_acl_header);
 103         for (n = 0; n < acl->a_count; n++) {
 104                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 105                 ext4_acl_entry *entry = (ext4_acl_entry *)e;
 106                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 107                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 108                 switch (acl_e->e_tag) {
 109                 case ACL_USER:
 110                         entry->e_id = cpu_to_le32(
 111                                 from_kuid(&init_user_ns, acl_e->e_uid));
 112                         e += sizeof(ext4_acl_entry);
 113                         break;
 114                 case ACL_GROUP:
 115                         entry->e_id = cpu_to_le32(
 116                                 from_kgid(&init_user_ns, acl_e->e_gid));
 117                         e += sizeof(ext4_acl_entry);
 118                         break;
 119
 120                 case ACL_USER_OBJ:
 121                 case ACL_GROUP_OBJ:
 122                 case ACL_MASK:
 123                 case ACL_OTHER:
 124                         e += sizeof(ext4_acl_entry_short);
 125                         break;
 126
 127                 default:
 128                         goto fail;
 129                 }
 130         }
 131         return (char *)ext_acl;
 132
 133 fail:
 134         kfree(ext_acl);
 135         return ERR_PTR(-EINVAL);
 136 }
 137
 138 /*
 139  * Inode operation get_posix_acl().
 140  *
 141  * inode->i_mutex: don't care
 142  */
 143 struct posix_acl *
 144 ext4_get_acl(struct inode *inode, int type)
 145 {
 146         int name_index;
 147         char *value = NULL;
 148         struct posix_acl *acl;
 149         int retval;
 150
 151         switch (type) {
 152         case ACL_TYPE_ACCESS:
 153                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 154                 break;
 155         case ACL_TYPE_DEFAULT:
 156                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 157                 break;
 158         default:
 159                 BUG();
 160         }
 161         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 162         if (retval > 0) {
 163                 value = kmalloc(retval, GFP_NOFS);
 164                 if (!value)
 165                         return ERR_PTR(-ENOMEM);
 166                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
 167         }
 168         if (retval > 0)
 169                 acl = ext4_acl_from_disk(value, retval);
 170         else if (retval == -ENODATA || retval == -ENOSYS)
 171                 acl = NULL;
 172         else
 173                 acl = ERR_PTR(retval);
 174         kfree(value);
 175
 176         return acl;
 177 }
 178
 179 /*
 180  * Set the access or default ACL of an inode.
 181  *
 182  * inode->i_mutex: down unless called from ext4_new_inode
 183  */
 184 static int
 185 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 186              struct posix_acl *acl, int xattr_flags)
 187 {
 188         int name_index;
 189         void *value = NULL;
 190         size_t size = 0;
 191         int error;
 192
 193         switch (type) {
 194         case ACL_TYPE_ACCESS:
 195                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 196                 break;
 197
 198         case ACL_TYPE_DEFAULT:
 199                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 200                 if (!S_ISDIR(inode->i_mode))
 201                         return acl ? -EACCES : 0;
 202                 break;
 203
 204         default:
 205                 return -EINVAL;
 206         }
 207         if (acl) {
 208                 value = ext4_acl_to_disk(acl, &size);
 209                 if (IS_ERR(value))
 210                         return (int)PTR_ERR(value);
 211         }
 212
 213         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 214                                       value, size, xattr_flags);
 215
 216         kfree(value);
 217         if (!error) {
 218                 set_cached_acl(inode, type, acl);
 219         }
 220
 221         return error;
 222 }
 223
 224 int
 225 ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 226 {
 227         handle_t *handle;
 228         int error, credits, retries = 0;
 229         size_t acl_size = acl ? ext4_acl_size(acl->a_count) : 0;
 230         umode_t mode = inode->i_mode;
 231         int update_mode = 0;
 232
 233         error = dquot_initialize(inode);
 234         if (error)
 235                 return error;
 236 retry:
 237         error = ext4_xattr_set_credits(inode, acl_size, false /* is_create */,
 238                                        &credits);
 239         if (error)
 240                 return error;
 241
 242         handle = ext4_journal_start(inode, EXT4_HT_XATTR, credits);
 243         if (IS_ERR(handle))
 244                 return PTR_ERR(handle);
 245
 246         if ((type == ACL_TYPE_ACCESS) && acl) {
 247                 error = posix_acl_update_mode(inode, &mode, &acl);
 248                 if (error)
 249                         goto out_stop;
 250                 update_mode = 1;
 251         }
 252
 253         error = __ext4_set_acl(handle, inode, type, acl, 0 /* xattr_flags */);
 254         if (!error && update_mode) {
 255                 inode->i_mode = mode;
 256                 inode->i_ctime = current_time(inode);
 257                 ext4_mark_inode_dirty(handle, inode);
 258         }
 259 out_stop:
 260         ext4_journal_stop(handle);
 261         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 262                 goto retry;
 263         return error;
 264 }
 265
 266 /*
 267  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 268  *
 269  * dir->i_mutex: down
 270  * inode->i_mutex: up (access to inode is still exclusive)
 271  */
 272 int
 273 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 274 {
 275         struct posix_acl *default_acl, *acl;
 276         int error;
 277
 278         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 279         if (error)
 280                 return error;
 281
 282         if (default_acl) {
 283                 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
 284                                        default_acl, XATTR_CREATE);
 285                 posix_acl_release(default_acl);
 286         }
 287         if (acl) {
 288                 if (!error)
 289                         error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
 290                                                acl, XATTR_CREATE);
 291                 posix_acl_release(acl);
 292         }
 293         return error;
 294 }