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                                 acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  57                                 break;
  58
  59                         case ACL_USER:
  60                         case ACL_GROUP:
  61                                 value = (char *)value + sizeof(ext2_acl_entry);
  62                                 if ((char *)value > end)
  63                                         goto fail;
  64                                 acl->a_entries[n].e_id =
  65                                         le32_to_cpu(entry->e_id);
  66                                 break;
  67
  68                         default:
  69                                 goto fail;
  70                 }
  71         }
  72         if (value != end)
  73                 goto fail;
  74         return acl;
  75
  76 fail:
  77         posix_acl_release(acl);
  78         return ERR_PTR(-EINVAL);
  79 }
  80
  81 /*
  82  * Convert from in-memory to filesystem representation.
  83  */
  84 static void *
  85 ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
  86 {
  87         ext2_acl_header *ext_acl;
  88         char *e;
  89         size_t n;
  90
  91         *size = ext2_acl_size(acl->a_count);
  92         ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
  93                         sizeof(ext2_acl_entry), GFP_KERNEL);
  94         if (!ext_acl)
  95                 return ERR_PTR(-ENOMEM);
  96         ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
  97         e = (char *)ext_acl + sizeof(ext2_acl_header);
  98         for (n=0; n < acl->a_count; n++) {
  99                 ext2_acl_entry *entry = (ext2_acl_entry *)e;
 100                 entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 101                 entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 102                 switch(acl->a_entries[n].e_tag) {
 103                         case ACL_USER:
 104                         case ACL_GROUP:
 105                                 entry->e_id =
 106                                         cpu_to_le32(acl->a_entries[n].e_id);
 107                                 e += sizeof(ext2_acl_entry);
 108                                 break;
 109
 110                         case ACL_USER_OBJ:
 111                         case ACL_GROUP_OBJ:
 112                         case ACL_MASK:
 113                         case ACL_OTHER:
 114                                 e += sizeof(ext2_acl_entry_short);
 115                                 break;
 116
 117                         default:
 118                                 goto fail;
 119                 }
 120         }
 121         return (char *)ext_acl;
 122
 123 fail:
 124         kfree(ext_acl);
 125         return ERR_PTR(-EINVAL);
 126 }
 127
 128 /*
 129  * inode->i_mutex: don't care
 130  */
 131 static struct posix_acl *
 132 ext2_get_acl(struct inode *inode, int type)
 133 {
 134         int name_index;
 135         char *value = NULL;
 136         struct posix_acl *acl;
 137         int retval;
 138
 139         if (!test_opt(inode->i_sb, POSIX_ACL))
 140                 return NULL;
 141
 142         acl = get_cached_acl(inode, type);
 143         if (acl != ACL_NOT_CACHED)
 144                 return acl;
 145
 146         switch (type) {
 147         case ACL_TYPE_ACCESS:
 148                 name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 149                 break;
 150         case ACL_TYPE_DEFAULT:
 151                 name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 152                 break;
 153         default:
 154                 BUG();
 155         }
 156         retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
 157         if (retval > 0) {
 158                 value = kmalloc(retval, GFP_KERNEL);
 159                 if (!value)
 160                         return ERR_PTR(-ENOMEM);
 161                 retval = ext2_xattr_get(inode, name_index, "", value, retval);
 162         }
 163         if (retval > 0)
 164                 acl = ext2_acl_from_disk(value, retval);
 165         else if (retval == -ENODATA || retval == -ENOSYS)
 166                 acl = NULL;
 167         else
 168                 acl = ERR_PTR(retval);
 169         kfree(value);
 170
 171         if (!IS_ERR(acl))
 172                 set_cached_acl(inode, type, acl);
 173
 174         return acl;
 175 }
 176
 177 /*
 178  * inode->i_mutex: down
 179  */
 180 static int
 181 ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 182 {
 183         int name_index;
 184         void *value = NULL;
 185         size_t size = 0;
 186         int error;
 187
 188         if (S_ISLNK(inode->i_mode))
 189                 return -EOPNOTSUPP;
 190         if (!test_opt(inode->i_sb, POSIX_ACL))
 191                 return 0;
 192
 193         switch(type) {
 194                 case ACL_TYPE_ACCESS:
 195                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 196                         if (acl) {
 197                                 mode_t mode = inode->i_mode;
 198                                 error = posix_acl_equiv_mode(acl, &mode);
 199                                 if (error < 0)
 200                                         return error;
 201                                 else {
 202                                         inode->i_mode = mode;
 203                                         inode->i_ctime = CURRENT_TIME_SEC;
 204                                         mark_inode_dirty(inode);
 205                                         if (error == 0)
 206                                                 acl = NULL;
 207                                 }
 208                         }
 209                         break;
 210
 211                 case ACL_TYPE_DEFAULT:
 212                         name_index = EXT2_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 = ext2_acl_to_disk(acl, &size);
 222                 if (IS_ERR(value))
 223                         return (int)PTR_ERR(value);
 224         }
 225
 226         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 227
 228         kfree(value);
 229         if (!error)
 230                 set_cached_acl(inode, type, acl);
 231         return error;
 232 }
 233
 234 int
 235 ext2_check_acl(struct inode *inode, int mask, unsigned int flags)
 236 {
 237         struct posix_acl *acl;
 238
 239         if (flags & IPERM_FLAG_RCU) {
 240                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 241                         return -ECHILD;
 242                 return -EAGAIN;
 243         }
 244
 245         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 246         if (IS_ERR(acl))
 247                 return PTR_ERR(acl);
 248         if (acl) {
 249                 int error = posix_acl_permission(inode, acl, mask);
 250                 posix_acl_release(acl);
 251                 return error;
 252         }
 253
 254         return -EAGAIN;
 255 }
 256
 257 /*
 258  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 259  *
 260  * dir->i_mutex: down
 261  * inode->i_mutex: up (access to inode is still exclusive)
 262  */
 263 int
 264 ext2_init_acl(struct inode *inode, struct inode *dir)
 265 {
 266         struct posix_acl *acl = NULL;
 267         int error = 0;
 268
 269         if (!S_ISLNK(inode->i_mode)) {
 270                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 271                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 272                         if (IS_ERR(acl))
 273                                 return PTR_ERR(acl);
 274                 }
 275                 if (!acl)
 276                         inode->i_mode &= ~current_umask();
 277         }
 278         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 279                struct posix_acl *clone;
 280                mode_t mode;
 281
 282                 if (S_ISDIR(inode->i_mode)) {
 283                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 284                         if (error)
 285                                 goto cleanup;
 286                 }
 287                 clone = posix_acl_clone(acl, GFP_KERNEL);
 288                 error = -ENOMEM;
 289                 if (!clone)
 290                         goto cleanup;
 291                 mode = inode->i_mode;
 292                 error = posix_acl_create_masq(clone, &mode);
 293                 if (error >= 0) {
 294                         inode->i_mode = mode;
 295                         if (error > 0) {
 296                                 /* This is an extended ACL */
 297                                 error = ext2_set_acl(inode,
 298                                                      ACL_TYPE_ACCESS, clone);
 299                         }
 300                 }
 301                 posix_acl_release(clone);
 302         }
 303 cleanup:
 304        posix_acl_release(acl);
 305        return error;
 306 }
 307
 308 /*
 309  * Does chmod for an inode that may have an Access Control List. The
 310  * inode->i_mode field must be updated to the desired value by the caller
 311  * before calling this function.
 312  * Returns 0 on success, or a negative error number.
 313  *
 314  * We change the ACL rather than storing some ACL entries in the file
 315  * mode permission bits (which would be more efficient), because that
 316  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 317  * for directories) are added. There are no more bits available in the
 318  * file mode.
 319  *
 320  * inode->i_mutex: down
 321  */
 322 int
 323 ext2_acl_chmod(struct inode *inode)
 324 {
 325         struct posix_acl *acl, *clone;
 326         int error;
 327
 328         if (!test_opt(inode->i_sb, POSIX_ACL))
 329                 return 0;
 330         if (S_ISLNK(inode->i_mode))
 331                 return -EOPNOTSUPP;
 332         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 333         if (IS_ERR(acl) || !acl)
 334                 return PTR_ERR(acl);
 335         clone = posix_acl_clone(acl, GFP_KERNEL);
 336         posix_acl_release(acl);
 337         if (!clone)
 338                 return -ENOMEM;
 339         error = posix_acl_chmod_masq(clone, inode->i_mode);
 340         if (!error)
 341                 error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
 342         posix_acl_release(clone);
 343         return error;
 344 }
 345
 346 /*
 347  * Extended attribut handlers
 348  */
 349 static size_t
 350 ext2_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_size,
 351                            const char *name, size_t name_len, int type)
 352 {
 353         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 354
 355         if (!test_opt(dentry->d_sb, POSIX_ACL))
 356                 return 0;
 357         if (list && size <= list_size)
 358                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 359         return size;
 360 }
 361
 362 static size_t
 363 ext2_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_size,
 364                             const char *name, size_t name_len, int type)
 365 {
 366         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 367
 368         if (!test_opt(dentry->d_sb, POSIX_ACL))
 369                 return 0;
 370         if (list && size <= list_size)
 371                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 372         return size;
 373 }
 374
 375 static int
 376 ext2_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 377                    size_t size, int type)
 378 {
 379         struct posix_acl *acl;
 380         int error;
 381
 382         if (strcmp(name, "") != 0)
 383                 return -EINVAL;
 384         if (!test_opt(dentry->d_sb, POSIX_ACL))
 385                 return -EOPNOTSUPP;
 386
 387         acl = ext2_get_acl(dentry->d_inode, type);
 388         if (IS_ERR(acl))
 389                 return PTR_ERR(acl);
 390         if (acl == NULL)
 391                 return -ENODATA;
 392         error = posix_acl_to_xattr(acl, buffer, size);
 393         posix_acl_release(acl);
 394
 395         return error;
 396 }
 397
 398 static int
 399 ext2_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 400                    size_t size, int flags, int type)
 401 {
 402         struct posix_acl *acl;
 403         int error;
 404
 405         if (strcmp(name, "") != 0)
 406                 return -EINVAL;
 407         if (!test_opt(dentry->d_sb, POSIX_ACL))
 408                 return -EOPNOTSUPP;
 409         if (!is_owner_or_cap(dentry->d_inode))
 410                 return -EPERM;
 411
 412         if (value) {
 413                 acl = posix_acl_from_xattr(value, size);
 414                 if (IS_ERR(acl))
 415                         return PTR_ERR(acl);
 416                 else if (acl) {
 417                         error = posix_acl_valid(acl);
 418                         if (error)
 419                                 goto release_and_out;
 420                 }
 421         } else
 422                 acl = NULL;
 423
 424         error = ext2_set_acl(dentry->d_inode, type, acl);
 425
 426 release_and_out:
 427         posix_acl_release(acl);
 428         return error;
 429 }
 430
 431 const struct xattr_handler ext2_xattr_acl_access_handler = {
 432         .prefix = POSIX_ACL_XATTR_ACCESS,
 433         .flags  = ACL_TYPE_ACCESS,
 434         .list   = ext2_xattr_list_acl_access,
 435         .get    = ext2_xattr_get_acl,
 436         .set    = ext2_xattr_set_acl,
 437 };
 438
 439 const struct xattr_handler ext2_xattr_acl_default_handler = {
 440         .prefix = POSIX_ACL_XATTR_DEFAULT,
 441         .flags  = ACL_TYPE_DEFAULT,
 442         .list   = ext2_xattr_list_acl_default,
 443         .get    = ext2_xattr_get_acl,
 444         .set    = ext2_xattr_set_acl,
 445 };