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