fs/ext2/acl.c

   1 /*
   2  * linux/fs/ext2/acl.c
   3  *
   4  * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   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 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                                 error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
 198                                 if (error)
 199                                         return error;
 200                                 inode->i_ctime = CURRENT_TIME_SEC;
 201                                 mark_inode_dirty(inode);
 202                         }
 203                         break;
 204
 205                 case ACL_TYPE_DEFAULT:
 206                         name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 207                         if (!S_ISDIR(inode->i_mode))
 208                                 return acl ? -EACCES : 0;
 209                         break;
 210
 211                 default:
 212                         return -EINVAL;
 213         }
 214         if (acl) {
 215                 value = ext2_acl_to_disk(acl, &size);
 216                 if (IS_ERR(value))
 217                         return (int)PTR_ERR(value);
 218         }
 219
 220         error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 221
 222         kfree(value);
 223         if (!error)
 224                 set_cached_acl(inode, type, acl);
 225         return error;
 226 }
 227
 228 /*
 229  * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 230  *
 231  * dir->i_mutex: down
 232  * inode->i_mutex: up (access to inode is still exclusive)
 233  */
 234 int
 235 ext2_init_acl(struct inode *inode, struct inode *dir)
 236 {
 237         struct posix_acl *acl = NULL;
 238         int error = 0;
 239
 240         if (!S_ISLNK(inode->i_mode)) {
 241                 if (test_opt(dir->i_sb, POSIX_ACL)) {
 242                         acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 243                         if (IS_ERR(acl))
 244                                 return PTR_ERR(acl);
 245                 }
 246                 if (!acl)
 247                         inode->i_mode &= ~current_umask();
 248         }
 249         if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 250                 if (S_ISDIR(inode->i_mode)) {
 251                         error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 252                         if (error)
 253                                 goto cleanup;
 254                 }
 255                 error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
 256                 if (error < 0)
 257                         return error;
 258                 if (error > 0) {
 259                         /* This is an extended ACL */
 260                         error = ext2_set_acl(inode, ACL_TYPE_ACCESS, acl);
 261                 }
 262         }
 263 cleanup:
 264        posix_acl_release(acl);
 265        return error;
 266 }
 267
 268 /*
 269  * Does chmod for an inode that may have an Access Control List. The
 270  * inode->i_mode field must be updated to the desired value by the caller
 271  * before calling this function.
 272  * Returns 0 on success, or a negative error number.
 273  *
 274  * We change the ACL rather than storing some ACL entries in the file
 275  * mode permission bits (which would be more efficient), because that
 276  * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 277  * for directories) are added. There are no more bits available in the
 278  * file mode.
 279  *
 280  * inode->i_mutex: down
 281  */
 282 int
 283 ext2_acl_chmod(struct inode *inode)
 284 {
 285         struct posix_acl *acl;
 286         int error;
 287
 288         if (!test_opt(inode->i_sb, POSIX_ACL))
 289                 return 0;
 290         if (S_ISLNK(inode->i_mode))
 291                 return -EOPNOTSUPP;
 292         acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 293         if (IS_ERR(acl) || !acl)
 294                 return PTR_ERR(acl);
 295         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 296         if (error)
 297                 return error;
 298         error = ext2_set_acl(inode, ACL_TYPE_ACCESS, acl);
 299         posix_acl_release(acl);
 300         return error;
 301 }
 302
 303 /*
 304  * Extended attribut handlers
 305  */
 306 static size_t
 307 ext2_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_size,
 308                            const char *name, size_t name_len, int type)
 309 {
 310         const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 311
 312         if (!test_opt(dentry->d_sb, POSIX_ACL))
 313                 return 0;
 314         if (list && size <= list_size)
 315                 memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 316         return size;
 317 }
 318
 319 static size_t
 320 ext2_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_size,
 321                             const char *name, size_t name_len, int type)
 322 {
 323         const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 324
 325         if (!test_opt(dentry->d_sb, POSIX_ACL))
 326                 return 0;
 327         if (list && size <= list_size)
 328                 memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 329         return size;
 330 }
 331
 332 static int
 333 ext2_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 334                    size_t size, int type)
 335 {
 336         struct posix_acl *acl;
 337         int error;
 338
 339         if (strcmp(name, "") != 0)
 340                 return -EINVAL;
 341         if (!test_opt(dentry->d_sb, POSIX_ACL))
 342                 return -EOPNOTSUPP;
 343
 344         acl = ext2_get_acl(dentry->d_inode, type);
 345         if (IS_ERR(acl))
 346                 return PTR_ERR(acl);
 347         if (acl == NULL)
 348                 return -ENODATA;
 349         error = posix_acl_to_xattr(acl, buffer, size);
 350         posix_acl_release(acl);
 351
 352         return error;
 353 }
 354
 355 static int
 356 ext2_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 357                    size_t size, int flags, int type)
 358 {
 359         struct posix_acl *acl;
 360         int error;
 361
 362         if (strcmp(name, "") != 0)
 363                 return -EINVAL;
 364         if (!test_opt(dentry->d_sb, POSIX_ACL))
 365                 return -EOPNOTSUPP;
 366         if (!inode_owner_or_capable(dentry->d_inode))
 367                 return -EPERM;
 368
 369         if (value) {
 370                 acl = posix_acl_from_xattr(value, size);
 371                 if (IS_ERR(acl))
 372                         return PTR_ERR(acl);
 373                 else if (acl) {
 374                         error = posix_acl_valid(acl);
 375                         if (error)
 376                                 goto release_and_out;
 377                 }
 378         } else
 379                 acl = NULL;
 380
 381         error = ext2_set_acl(dentry->d_inode, type, acl);
 382
 383 release_and_out:
 384         posix_acl_release(acl);
 385         return error;
 386 }
 387
 388 const struct xattr_handler ext2_xattr_acl_access_handler = {
 389         .prefix = POSIX_ACL_XATTR_ACCESS,
 390         .flags  = ACL_TYPE_ACCESS,
 391         .list   = ext2_xattr_list_acl_access,
 392         .get    = ext2_xattr_get_acl,
 393         .set    = ext2_xattr_set_acl,
 394 };
 395
 396 const struct xattr_handler ext2_xattr_acl_default_handler = {
 397         .prefix = POSIX_ACL_XATTR_DEFAULT,
 398         .flags  = ACL_TYPE_DEFAULT,
 399         .list   = ext2_xattr_list_acl_default,
 400         .get    = ext2_xattr_get_acl,
 401         .set    = ext2_xattr_set_acl,
 402 };