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         if (!IS_ERR(acl))
 176                 set_cached_acl(inode, type, acl);
 177
 178         return acl;
 179 }
 180
 181 /*
 182  * Set the access or default ACL of an inode.
 183  *
 184  * inode->i_mutex: down unless called from ext4_new_inode
 185  */
 186 static int
 187 __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
 188              struct posix_acl *acl)
 189 {
 190         int name_index;
 191         void *value = NULL;
 192         size_t size = 0;
 193         int error;
 194
 195         switch (type) {
 196         case ACL_TYPE_ACCESS:
 197                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
 198                 if (acl) {
 199                         error = posix_acl_equiv_mode(acl, &inode->i_mode);
 200                         if (error < 0)
 201                                 return error;
 202                         else {
 203                                 inode->i_ctime = ext4_current_time(inode);
 204                                 ext4_mark_inode_dirty(handle, inode);
 205                                 if (error == 0)
 206                                         acl = NULL;
 207                         }
 208                 }
 209                 break;
 210
 211         case ACL_TYPE_DEFAULT:
 212                 name_index = EXT4_XATTR_INDEX_POSIX_ACL_DEFAULT;
 213                 if (!S_ISDIR(inode->i_mode))
 214                         return acl ? -EACCES : 0;
 215                 break;
 216
 217         default:
 218                 return -EINVAL;
 219         }
 220         if (acl) {
 221                 value = ext4_acl_to_disk(acl, &size);
 222                 if (IS_ERR(value))
 223                         return (int)PTR_ERR(value);
 224         }
 225
 226         error = ext4_xattr_set_handle(handle, inode, name_index, "",
 227                                       value, size, 0);
 228
 229         kfree(value);
 230         if (!error)
 231                 set_cached_acl(inode, type, acl);
 232
 233         return error;
 234 }
 235
 236 int
 237 ext4_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 = ext4_journal_start(inode, EXT4_HT_XATTR,
 244                                     ext4_jbd2_credits_xattr(inode));
 245         if (IS_ERR(handle))
 246                 return PTR_ERR(handle);
 247
 248         error = __ext4_set_acl(handle, inode, type, acl);
 249         ext4_journal_stop(handle);
 250         if (error == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
 251                 goto retry;
 252         return error;
 253 }
 254
 255 /*
 256  * Initialize the ACLs of a new inode. Called from ext4_new_inode.
 257  *
 258  * dir->i_mutex: down
 259  * inode->i_mutex: up (access to inode is still exclusive)
 260  */
 261 int
 262 ext4_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 263 {
 264         struct posix_acl *default_acl, *acl;
 265         int error;
 266
 267         error = posix_acl_create(dir, &inode->i_mode, &default_acl, &acl);
 268         if (error)
 269                 return error;
 270
 271         if (default_acl) {
 272                 error = __ext4_set_acl(handle, inode, ACL_TYPE_DEFAULT,
 273                                        default_acl);
 274                 posix_acl_release(default_acl);
 275         }
 276         if (acl) {
 277                 if (!error)
 278                         error = __ext4_set_acl(handle, inode, ACL_TYPE_ACCESS,
 279                                                acl);
 280                 posix_acl_release(acl);
 281         }
 282         return error;
 283 }