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/init.h>
   8 #include <linux/sched.h>
   9 #include <linux/slab.h>
  10 #include <linux/capability.h>
  11 #include <linux/fs.h>
  12 #include "ext4_jbd2.h"
  13 #include "ext4.h"
  14 #include "xattr.h"
  15 #include "acl.h"
  16
  17 /*
  18  * Convert from filesystem to in-memory representation.
  19  */
  20 static struct posix_acl *
  21 ext4_acl_from_disk(const void *value, size_t size)
  22 {
  23         const char *end = (char *)value + size;
  24         int n, count;
  25         struct posix_acl *acl;
  26
  27         if (!value)
  28                 return NULL;
  29         if (size < sizeof(ext4_acl_header))
  30                  return ERR_PTR(-EINVAL);
  31         if (((ext4_acl_header *)value)->a_version !=
  32             cpu_to_le32(EXT4_ACL_VERSION))
  33                 return ERR_PTR(-EINVAL);
  34         value = (char *)value + sizeof(ext4_acl_header);
  35         count = ext4_acl_count(size);
  36         if (count < 0)
  37                 return ERR_PTR(-EINVAL);
  38         if (count == 0)
  39                 return NULL;
  40         acl = posix_acl_alloc(count, GFP_NOFS);
  41         if (!acl)
  42                 return ERR_PTR(-ENOMEM);
  43         for (n = 0; n < count; n++) {
  44                 ext4_acl_entry *entry =
  45                         (ext4_acl_entry *)value;
  46                 if ((char *)value + sizeof(ext4_acl_entry_short) > end)
  47                         goto fail;
  48                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  49                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  50
  51                 switch (acl->a_entries[n].e_tag) {
  52                 case ACL_USER_OBJ:
  53                 case ACL_GROUP_OBJ:
  54                 case ACL_MASK:
  55                 case ACL_OTHER:
  56                         value = (char *)value +
  57                                 sizeof(ext4_acl_entry_short);
  58                         break;
  59
  60                 case ACL_USER:
  61                         value = (char *)value + sizeof(ext4_acl_entry);
  62                         if ((char *)value > end)
  63                                 goto fail;
  64                         acl->a_entries[n].e_uid =
  65                                 make_kuid(&init_user_ns,
  66                                           le32_to_cpu(entry->e_id));
  67                         break;
  68                 case ACL_GROUP:
  69                         value = (char *)value + sizeof(ext4_acl_entry);
  70                         if ((char *)value > end)
  71                                 goto fail;
  72                         acl->a_entries[n].e_gid =
  73                                 make_kgid(&init_user_ns,
  74                                           le32_to_cpu(entry->e_id));
  75                         break;
  76
  77                 default:
  78                         goto fail;
  79                 }
  80         }
  81         if (value != end)
  82                 goto fail;
  83         return acl;
  84
  85 fail:
  86         posix_acl_release(acl);
  87         return ERR_PTR(-EINVAL);
  88 }
  89
  90 /*
  91  * Convert from in-memory to filesystem representation.
  92  */
  93 static void *
  94 ext4_acl_to_disk(const struct posix_acl *acl, size_t *size)
  95 {
  96         ext4_acl_header *ext_acl;
  97         char *e;
  98         size_t n;
  99
 100         *size = ext4_acl_size(acl->a_count);
 101         ext_acl = kmalloc(sizeof(ext4_acl_header) + acl->a_count *
 102                         sizeof(ext4_acl_entry), GFP_NOFS);
 103         if (!ext_acl)
 104                 return ERR_PTR(-ENOMEM);
 105         ext_acl->a_version = cpu_to_le32(EXT4_ACL_VERSION);
 106         e = (char *)ext_acl + sizeof(ext4_acl_header);
 107         for (n = 0; n < acl->a_count; n++) {
 108                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 109                 ext4_acl_entry *entry = (ext4_acl_entry *)e;
 110                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 111                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 112                 switch (acl_e->e_tag) {
 113                 case ACL_USER:
 114                         entry->e_id = cpu_to_le32(
 115                                 from_kuid(&init_user_ns, acl_e->e_uid));
 116                         e += sizeof(ext4_acl_entry);
 117                         break;
 118                 case ACL_GROUP:
 119                         entry->e_id = cpu_to_le32(
 120                                 from_kgid(&init_user_ns, acl_e->e_gid));
 121                         e += sizeof(ext4_acl_entry);
 122                         break;
 123
 124                 case ACL_USER_OBJ:
 125                 case ACL_GROUP_OBJ:
 126                 case ACL_MASK:
 127                 case ACL_OTHER:
 128                         e += sizeof(ext4_acl_entry_short);
 129                         break;
 130
 131                 default:
 132                         goto fail;
 133                 }
 134         }
 135         return (char *)ext_acl;
 136
 137 fail:
 138         kfree(ext_acl);
 139         return ERR_PTR(-EINVAL);
 140 }
 141
 142 /*
 143  * Inode operation get_posix_acl().
 144  *
 145  * inode->i_mutex: don't care
 146  */
 147 struct posix_acl *
 148 ext4_get_acl(struct inode *inode, int type)
 149 {
 150         int name_index;
 151         char *value = NULL;
 152         struct posix_acl *acl;
 153         int retval;
 154
 155         switch (type) {
 156         case ACL_TYPE_ACCESS:
 157                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 158                 break;
 159         case ACL_TYPE_DEFAULT:
 160                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 161                 break;
 162         default:
 163                 BUG();
 164         }
 165         retval = ext4_xattr_get(inode, name_index, "", NULL, 0);
 166         if (retval > 0) {
 167                 value = kmalloc(retval, GFP_NOFS);
 168                 if (!value)
 169                         return ERR_PTR(-ENOMEM);
 170                 retval = ext4_xattr_get(inode, name_index, "", value, retval);
 171         }
 172         if (retval > 0)
 173                 acl = ext4_acl_from_disk(value, retval);
 174         else if (retval == -ENODATA || retval == -ENOSYS)
 175                 acl = NULL;
 176         else
 177                 acl = ERR_PTR(retval);
 178         kfree(value);
 179
 180         if (!IS_ERR(acl))
 181                 set_cached_acl(inode, type, acl);
 182
 183         return acl;
 184 }
 185
 186 /*
 187  * Set the access or default ACL of an inode.
 188  *
 189  * inode->i_mutex: down unless called from ext4_new_inode
 190  */
 191 static int
 192 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 193              struct posix_acl *acl)
 194 {
 195         int name_index;
 196         void *value = NULL;
 197         size_t size = 0;
 198         int error;
 199
 200         switch (type) {
 201         case ACL_TYPE_ACCESS:
 202                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 203                 if (acl) {
 204                         error = posix_acl_equiv_mode(acl, &inode->i_mode);
 205                         if (error < 0)
 206                                 return error;
 207                         else {
 208                                 inode->i_ctime = ext4_current_time(inode);
 209                                 ext4_mark_inode_dirty(handle, inode);
 210                                 if (error == 0)
 211                                         acl = NULL;
 212                         }
 213                 }
 214                 break;
 215
 216         case ACL_TYPE_DEFAULT:
 217                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 218                 if (!S_ISDIR(inode->i_mode))
 219                         return acl ? -EACCES : 0;
 220                 break;
 221
 222         default:
 223                 return -EINVAL;
 224         }
 225         if (acl) {
 226                 value = ext4_acl_to_disk(acl, &size);
 227                 if (IS_ERR(value))
 228                         return (int)PTR_ERR(value);
 229         }
 230
 231         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 232                                       value, size, 0);
 233
 234         kfree(value);
 235         if (!error)
 236                 set_cached_acl(inode, type, acl);
 237
 238         return error;
 239 }
 240
 241 int
 242 ext4_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 243 {
 244         handle_t *handle;
 245         int error, retries = 0;
 246
 247 retry:
 248         handle = ext4_journal_start(inode, EXT4_HT_XATTR,
 249                                     ext4_jbd2_credits_xattr(inode));
 250         if (IS_ERR(handle))
 251                 return PTR_ERR(handle);
 252
 253         error = __ext4_set_acl(handle, inode, type, acl);
 254         ext4_journal_stop(handle);
 255         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 256                 goto retry;
 257         return error;
 258 }
 259
 260 /*
 261  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 262  *
 263  * dir->i_mutex: down
 264  * inode->i_mutex: up (access to inode is still exclusive)
 265  */
 266 int
 267 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 268 {
 269         struct posix_acl *default_acl, *acl;
 270         int error;
 271
 272         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 273         if (error)
 274                 return error;
 275
 276         if (default_acl) {
 277                 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
 278                                        default_acl);
 279                 posix_acl_release(default_acl);
 280         }
 281         if (acl) {
 282                 if (!error)
 283                         error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
 284                                                acl);
 285                 posix_acl_release(acl);
 286         }
 287         return error;
 288 }