fs/ext2/acl.c

   1 /*
   2  * linux/fs/ext2/acl.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <[email protected]>
   5  */
   6
   7 #include <linux/capability.h>
   8 #include <linux/init.h>
   9 #include <linux/sched.h>
  10 #include <linux/slab.h>
  11 #include <linux/fs.h>
  12 #include "ext2.h"
  13 #include "xattr.h"
  14 #include "acl.h"
  15
  16 /*
  17  * Convert from filesystem to in-memory representation.
  18  */
  19 static struct posix_acl *
  20 ext2_acl_from_disk(const void *value, size_t size)
  21 {
  22         const char *end = (char *)value + size;
  23         int n, count;
  24         struct posix_acl *acl;
  25
  26         if (!value)
  27                 return NULL;
  28         if (size < sizeof(ext2_acl_header))
  29                  return ERR_PTR(-EINVAL);
  30         if (((ext2_acl_header *)value)->a_version !=
  31             cpu_to_le32(EXT2_ACL_VERSION))
  32                 return ERR_PTR(-EINVAL);
  33         value = (char *)value + sizeof(ext2_acl_header);
  34         count = ext2_acl_count(size);
  35         if (count < 0)
  36                 return ERR_PTR(-EINVAL);
  37         if (count == 0)
  38                 return NULL;
  39         acl = posix_acl_alloc(count, GFP_KERNEL);
  40         if (!acl)
  41                 return ERR_PTR(-ENOMEM);
  42         for (n=0; n < count; n++) {
  43                 ext2_acl_entry *entry =
  44                         (ext2_acl_entry *)value;
  45                 if ((char *)value + sizeof(ext2_acl_entry_short) > end)
  46                         goto fail;
  47                 acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  48                 acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  49                 switch(acl->a_entries[n].e_tag) {
  50                         case ACL_USER_OBJ:
  51                         case ACL_GROUP_OBJ:
  52                         case ACL_MASK:
  53                         case ACL_OTHER:
  54                                 value = (char *)value +
  55                                         sizeof(ext2_acl_entry_short);
  56                                 break;
  57
  58                         case ACL_USER:
  59                                 value = (char *)value + sizeof(ext2_acl_entry);
  60                                 if ((char *)value > end)
  61                                         goto fail;
  62                                 acl->a_entries[n].e_uid =
  63                                         make_kuid(&init_user_ns,
  64                                                   le32_to_cpu(entry->e_id));
  65                                 break;
  66                         case ACL_GROUP:
  67                                 value = (char *)value + sizeof(ext2_acl_entry);
  68                                 if ((char *)value > end)
  69                                         goto fail;
  70                                 acl->a_entries[n].e_gid =
  71                                         make_kgid(&init_user_ns,
  72                                                   le32_to_cpu(entry->e_id));
  73                                 break;
  74
  75                         default:
  76                                 goto fail;
  77                 }
  78         }
  79         if (value != end)
  80                 goto fail;
  81         return acl;
  82
  83 fail:
  84         posix_acl_release(acl);
  85         return ERR_PTR(-EINVAL);
  86 }
  87
  88 /*
  89  * Convert from in-memory to filesystem representation.
  90  */
  91 static void *
  92 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
  93 {
  94         ext2_acl_header *ext_acl;
  95         char *e;
  96         size_t n;
  97
  98         *size = ext2_acl_size(acl->a_count);
  99         ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
 100                         sizeof(ext2_acl_entry), GFP_KERNEL);
 101         if (!ext_acl)
 102                 return ERR_PTR(-ENOMEM);
 103         ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
 104         e = (char *)ext_acl + sizeof(ext2_acl_header);
 105         for (n=0; n < acl->a_count; n++) {
 106                 const struct posix_acl_entry *acl_e = &acl->a_entries[n];
 107                 ext2_acl_entry *entry = (ext2_acl_entry *)e;
 108                 entry->e_tag  = cpu_to_le16(acl_e->e_tag);
 109                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 110                 switch(acl_e->e_tag) {
 111                         case ACL_USER:
 112                                 entry->e_id = cpu_to_le32(
 113                                         from_kuid(&init_user_ns, acl_e->e_uid));
 114                                 e += sizeof(ext2_acl_entry);
 115                                 break;
 116                         case ACL_GROUP:
 117                                 entry->e_id = cpu_to_le32(
 118                                         from_kgid(&init_user_ns, acl_e->e_gid));
 119                                 e += sizeof(ext2_acl_entry);
 120                                 break;
 121
 122                         case ACL_USER_OBJ:
 123                         case ACL_GROUP_OBJ:
 124                         case ACL_MASK:
 125                         case ACL_OTHER:
 126                                 e += sizeof(ext2_acl_entry_short);
 127                                 break;
 128
 129                         default:
 130                                 goto fail;
 131                 }
 132         }
 133         return (char *)ext_acl;
 134
 135 fail:
 136         kfree(ext_acl);
 137         return ERR_PTR(-EINVAL);
 138 }
 139
 140 /*
 141  * inode->i_mutex: don't care
 142  */
 143 struct posix_acl *
 144 ext2_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         if (!test_opt(inode->i_sb, POSIX_ACL))
 152                 return NULL;
 153
 154         acl = get_cached_acl(inode, type);
 155         if (acl != ACL_NOT_CACHED)
 156                 return acl;
 157
 158         switch (type) {
 159         case ACL_TYPE_ACCESS:
 160                 name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 161                 break;
 162         case ACL_TYPE_DEFAULT:
 163                 name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 164                 break;
 165         default:
 166                 BUG();
 167         }
 168         retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
 169         if (retval > 0) {
 170                 value = kmalloc(retval, GFP_KERNEL);
 171                 if (!value)
 172                         return ERR_PTR(-ENOMEM);
 173                 retval = ext2_xattr_get(inode, name_index, "", value, retval);
 174         }
 175         if (retval > 0)
 176                 acl = ext2_acl_from_disk(value, retval);
 177         else if (retval == -ENODATA || retval == -ENOSYS)
 178                 acl = NULL;
 179         else
 180                 acl = ERR_PTR(retval);
 181         kfree(value);
 182
 183         if (!IS_ERR(acl))
 184                 set_cached_acl(inode, type, acl);
 185
 186         return acl;
 187 }
 188
 189 /*
 190  * inode->i_mutex: down
 191  */
 192 static int
 193 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 194 {
 195         int name_index;
 196         void *value = NULL;
 197         size_t size = 0;
 198         int error;
 199
 200         if (S_ISLNK(inode->i_mode))
 201                 return -EOPNOTSUPP;
 202         if (!test_opt(inode->i_sb, POSIX_ACL))
 203                 return 0;
 204
 205         switch(type) {
 206                 case ACL_TYPE_ACCESS:
 207                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 208                         if (acl) {
 209                                 error = posix_acl_equiv_mode(acl, &inode->i_mode);
 210                                 if (error < 0)
 211                                         return error;
 212                                 else {
 213                                         inode->i_ctime = CURRENT_TIME_SEC;
 214                                         mark_inode_dirty(inode);
 215                                         if (error == 0)
 216                                                 acl = NULL;
 217                                 }
 218                         }
 219                         break;
 220
 221                 case ACL_TYPE_DEFAULT:
 222                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 223                         if (!S_ISDIR(inode->i_mode))
 224                                 return acl ? -EACCES : 0;
 225                         break;
 226
 227                 default:
 228                         return -EINVAL;
 229         }
 230         if (acl) {
 231                 value = ext2_acl_to_disk(acl, &size);
 232                 if (IS_ERR(value))
 233                         return (int)PTR_ERR(value);
 234         }
 235
 236         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 237
 238         kfree(value);
 239         if (!error)
 240                 set_cached_acl(inode, type, acl);
 241         return error;
 242 }
 243
 244 /*
 245  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 246  *
 247  * dir->i_mutex: down
 248  * inode->i_mutex: up (access to inode is still exclusive)
 249  */
 250 int
 251 ext2_init_acl(struct inode *inode, struct inode *dir)
 252 {
 253         struct posix_acl *acl = NULL;
 254         int error = 0;
 255
 256         if (!S_ISLNK(inode->i_mode)) {
 257                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 258                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 259                         if (IS_ERR(acl))
 260                                 return PTR_ERR(acl);
 261                 }
 262                 if (!acl)
 263                         inode->i_mode &= ~current_umask();
 264         }
 265         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 266                 if (S_ISDIR(inode->i_mode)) {
 267                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 268                         if (error)
 269                                 goto cleanup;
 270                 }
 271                 error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
 272                 if (error < 0)
 273                         return error;
 274                 if (error > 0) {
 275                         /* This is an extended ACL */
 276                         error = ext2_set_acl(inode, ACL_TYPE_ACCESS, acl);
 277                 }
 278         }
 279 cleanup:
 280        posix_acl_release(acl);
 281        return error;
 282 }
 283
 284 /*
 285  * Does chmod for an inode that may have an Access Control List. The
 286  * inode->i_mode field must be updated to the desired value by the caller
 287  * before calling this function.
 288  * Returns 0 on success, or a negative error number.
 289  *
 290  * We change the ACL rather than storing some ACL entries in the file
 291  * mode permission bits (which would be more efficient), because that
 292  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 293  * for directories) are added. There are no more bits available in the
 294  * file mode.
 295  *
 296  * inode->i_mutex: down
 297  */
 298 int
 299 ext2_acl_chmod(struct inode *inode)
 300 {
 301         struct posix_acl *acl;
 302         int error;
 303
 304         if (!test_opt(inode->i_sb, POSIX_ACL))
 305                 return 0;
 306         if (S_ISLNK(inode->i_mode))
 307                 return -EOPNOTSUPP;
 308         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 309         if (IS_ERR(acl) || !acl)
 310                 return PTR_ERR(acl);
 311         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 312         if (error)
 313                 return error;
 314         error = ext2_set_acl(inode, ACL_TYPE_ACCESS, acl);
 315         posix_acl_release(acl);
 316         return error;
 317 }
 318
 319 /*
 320  * Extended attribut handlers
 321  */
 322 static size_t
 323 ext2_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_size,
 324                            const char *name, size_t name_len, int type)
 325 {
 326         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 327
 328         if (!test_opt(dentry->d_sb, POSIX_ACL))
 329                 return 0;
 330         if (list && size <= list_size)
 331                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 332         return size;
 333 }
 334
 335 static size_t
 336 ext2_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_size,
 337                             const char *name, size_t name_len, int type)
 338 {
 339         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 340
 341         if (!test_opt(dentry->d_sb, POSIX_ACL))
 342                 return 0;
 343         if (list && size <= list_size)
 344                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 345         return size;
 346 }
 347
 348 static int
 349 ext2_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 350                    size_t size, int type)
 351 {
 352         struct posix_acl *acl;
 353         int error;
 354
 355         if (strcmp(name, "") != 0)
 356                 return -EINVAL;
 357         if (!test_opt(dentry->d_sb, POSIX_ACL))
 358                 return -EOPNOTSUPP;
 359
 360         acl = ext2_get_acl(dentry->d_inode, type);
 361         if (IS_ERR(acl))
 362                 return PTR_ERR(acl);
 363         if (acl == NULL)
 364                 return -ENODATA;
 365         error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 366         posix_acl_release(acl);
 367
 368         return error;
 369 }
 370
 371 static int
 372 ext2_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 373                    size_t size, int flags, int type)
 374 {
 375         struct posix_acl *acl;
 376         int error;
 377
 378         if (strcmp(name, "") != 0)
 379                 return -EINVAL;
 380         if (!test_opt(dentry->d_sb, POSIX_ACL))
 381                 return -EOPNOTSUPP;
 382         if (!inode_owner_or_capable(dentry->d_inode))
 383                 return -EPERM;
 384
 385         if (value) {
 386                 acl = posix_acl_from_xattr(&init_user_ns, value, size);
 387                 if (IS_ERR(acl))
 388                         return PTR_ERR(acl);
 389                 else if (acl) {
 390                         error = posix_acl_valid(acl);
 391                         if (error)
 392                                 goto release_and_out;
 393                 }
 394         } else
 395                 acl = NULL;
 396
 397         error = ext2_set_acl(dentry->d_inode, type, acl);
 398
 399 release_and_out:
 400         posix_acl_release(acl);
 401         return error;
 402 }
 403
 404 const struct xattr_handler ext2_xattr_acl_access_handler = {
 405         .prefix = POSIX_ACL_XATTR_ACCESS,
 406         .flags  = ACL_TYPE_ACCESS,
 407         .list   = ext2_xattr_list_acl_access,
 408         .get    = ext2_xattr_get_acl,
 409         .set    = ext2_xattr_set_acl,
 410 };
 411
 412 const struct xattr_handler ext2_xattr_acl_default_handler = {
 413         .prefix = POSIX_ACL_XATTR_DEFAULT,
 414         .flags  = ACL_TYPE_DEFAULT,
 415         .list   = ext2_xattr_list_acl_default,
 416         .get    = ext2_xattr_get_acl,
 417         .set    = ext2_xattr_set_acl,
 418 };