linux/fs/ext3/acl.c
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   1/*
   2 * linux/fs/ext3/acl.c
   3 *
   4 * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   5 */
   6
   7#include <linux/init.h>
   8#include <linux/sched.h>
   9#include <linux/slab.h>
  10#include <linux/capability.h>
  11#include <linux/fs.h>
  12#include <linux/ext3_jbd.h>
  13#include <linux/ext3_fs.h>
  14#include "xattr.h"
  15#include "acl.h"
  16
  17/*
  18 * Convert from filesystem to in-memory representation.
  19 */
  20static struct posix_acl *
  21ext3_acl_from_disk(const void *value, size_t size)
  22{
  23        const char *end = (char *)value + size;
  24        int n, count;
  25        struct posix_acl *acl;
  26
  27        if (!value)
  28                return NULL;
  29        if (size < sizeof(ext3_acl_header))
  30                 return ERR_PTR(-EINVAL);
  31        if (((ext3_acl_header *)value)->a_version !=
  32            cpu_to_le32(EXT3_ACL_VERSION))
  33                return ERR_PTR(-EINVAL);
  34        value = (char *)value + sizeof(ext3_acl_header);
  35        count = ext3_acl_count(size);
  36        if (count < 0)
  37                return ERR_PTR(-EINVAL);
  38        if (count == 0)
  39                return NULL;
  40        acl = posix_acl_alloc(count, GFP_NOFS);
  41        if (!acl)
  42                return ERR_PTR(-ENOMEM);
  43        for (n=0; n < count; n++) {
  44                ext3_acl_entry *entry =
  45                        (ext3_acl_entry *)value;
  46                if ((char *)value + sizeof(ext3_acl_entry_short) > end)
  47                        goto fail;
  48                acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  49                acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  50                switch(acl->a_entries[n].e_tag) {
  51                        case ACL_USER_OBJ:
  52                        case ACL_GROUP_OBJ:
  53                        case ACL_MASK:
  54                        case ACL_OTHER:
  55                                value = (char *)value +
  56                                        sizeof(ext3_acl_entry_short);
  57                                acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  58                                break;
  59
  60                        case ACL_USER:
  61                        case ACL_GROUP:
  62                                value = (char *)value + sizeof(ext3_acl_entry);
  63                                if ((char *)value > end)
  64                                        goto fail;
  65                                acl->a_entries[n].e_id =
  66                                        le32_to_cpu(entry->e_id);
  67                                break;
  68
  69                        default:
  70                                goto fail;
  71                }
  72        }
  73        if (value != end)
  74                goto fail;
  75        return acl;
  76
  77fail:
  78        posix_acl_release(acl);
  79        return ERR_PTR(-EINVAL);
  80}
  81
  82/*
  83 * Convert from in-memory to filesystem representation.
  84 */
  85static void *
  86ext3_acl_to_disk(const struct posix_acl *acl, size_t *size)
  87{
  88        ext3_acl_header *ext_acl;
  89        char *e;
  90        size_t n;
  91
  92        *size = ext3_acl_size(acl->a_count);
  93        ext_acl = kmalloc(sizeof(ext3_acl_header) + acl->a_count *
  94                        sizeof(ext3_acl_entry), GFP_NOFS);
  95        if (!ext_acl)
  96                return ERR_PTR(-ENOMEM);
  97        ext_acl->a_version = cpu_to_le32(EXT3_ACL_VERSION);
  98        e = (char *)ext_acl + sizeof(ext3_acl_header);
  99        for (n=0; n < acl->a_count; n++) {
 100                ext3_acl_entry *entry = (ext3_acl_entry *)e;
 101                entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
 102                entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
 103                switch(acl->a_entries[n].e_tag) {
 104                        case ACL_USER:
 105                        case ACL_GROUP:
 106                                entry->e_id =
 107                                        cpu_to_le32(acl->a_entries[n].e_id);
 108                                e += sizeof(ext3_acl_entry);
 109                                break;
 110
 111                        case ACL_USER_OBJ:
 112                        case ACL_GROUP_OBJ:
 113                        case ACL_MASK:
 114                        case ACL_OTHER:
 115                                e += sizeof(ext3_acl_entry_short);
 116                                break;
 117
 118                        default:
 119                                goto fail;
 120                }
 121        }
 122        return (char *)ext_acl;
 123
 124fail:
 125        kfree(ext_acl);
 126        return ERR_PTR(-EINVAL);
 127}
 128
 129/*
 130 * Inode operation get_posix_acl().
 131 *
 132 * inode->i_mutex: don't care
 133 */
 134static struct posix_acl *
 135ext3_get_acl(struct inode *inode, int type)
 136{
 137        int name_index;
 138        char *value = NULL;
 139        struct posix_acl *acl;
 140        int retval;
 141
 142        if (!test_opt(inode->i_sb, POSIX_ACL))
 143                return NULL;
 144
 145        acl = get_cached_acl(inode, type);
 146        if (acl != ACL_NOT_CACHED)
 147                return acl;
 148
 149        switch (type) {
 150        case ACL_TYPE_ACCESS:
 151                name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 152                break;
 153        case ACL_TYPE_DEFAULT:
 154                name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 155                break;
 156        default:
 157                BUG();
 158        }
 159
 160        retval = ext3_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 = ext3_xattr_get(inode, name_index, "", value, retval);
 166        }
 167        if (retval > 0)
 168                acl = ext3_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 ext3_new_inode
 185 */
 186static int
 187ext3_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        if (S_ISLNK(inode->i_mode))
 196                return -EOPNOTSUPP;
 197
 198        switch(type) {
 199                case ACL_TYPE_ACCESS:
 200                        name_index = EXT3_XATTR_INDEX_POSIX_ACL_ACCESS;
 201                        if (acl) {
 202                                mode_t mode = inode->i_mode;
 203                                error = posix_acl_equiv_mode(acl, &mode);
 204                                if (error < 0)
 205                                        return error;
 206                                else {
 207                                        inode->i_mode = mode;
 208                                        inode->i_ctime = CURRENT_TIME_SEC;
 209                                        ext3_mark_inode_dirty(handle, inode);
 210                                        if (error == 0)
 211                                                acl = NULL;
 212                                }
 213                        }
 214                        break;
 215
 216                case ACL_TYPE_DEFAULT:
 217                        name_index = EXT3_XATTR_INDEX_POSIX_ACL_DEFAULT;
 218                        if (!S_ISDIR(inode->i_mode))
 219                                return acl ? -EACCES : 0;
 220                        break;
 221
 222                default:
 223                        return -EINVAL;
 224        }
 225        if (acl) {
 226                value = ext3_acl_to_disk(acl, &size);
 227                if (IS_ERR(value))
 228                        return (int)PTR_ERR(value);
 229        }
 230
 231        error = ext3_xattr_set_handle(handle, inode, name_index, "",
 232                                      value, size, 0);
 233
 234        kfree(value);
 235
 236        if (!error)
 237                set_cached_acl(inode, type, acl);
 238
 239        return error;
 240}
 241
 242int
 243ext3_check_acl(struct inode *inode, int mask, unsigned int flags)
 244{
 245        struct posix_acl *acl;
 246
 247        if (flags & IPERM_FLAG_RCU) {
 248                if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 249                        return -ECHILD;
 250                return -EAGAIN;
 251        }
 252
 253        acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 254        if (IS_ERR(acl))
 255                return PTR_ERR(acl);
 256        if (acl) {
 257                int error = posix_acl_permission(inode, acl, mask);
 258                posix_acl_release(acl);
 259                return error;
 260        }
 261
 262        return -EAGAIN;
 263}
 264
 265/*
 266 * Initialize the ACLs of a new inode. Called from ext3_new_inode.
 267 *
 268 * dir->i_mutex: down
 269 * inode->i_mutex: up (access to inode is still exclusive)
 270 */
 271int
 272ext3_init_acl(handle_t *handle, struct inode *inode, struct inode *dir)
 273{
 274        struct posix_acl *acl = NULL;
 275        int error = 0;
 276
 277        if (!S_ISLNK(inode->i_mode)) {
 278                if (test_opt(dir->i_sb, POSIX_ACL)) {
 279                        acl = ext3_get_acl(dir, ACL_TYPE_DEFAULT);
 280                        if (IS_ERR(acl))
 281                                return PTR_ERR(acl);
 282                }
 283                if (!acl)
 284                        inode->i_mode &= ~current_umask();
 285        }
 286        if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 287                struct posix_acl *clone;
 288                mode_t mode;
 289
 290                if (S_ISDIR(inode->i_mode)) {
 291                        error = ext3_set_acl(handle, inode,
 292                                             ACL_TYPE_DEFAULT, acl);
 293                        if (error)
 294                                goto cleanup;
 295                }
 296                clone = posix_acl_clone(acl, GFP_NOFS);
 297                error = -ENOMEM;
 298                if (!clone)
 299                        goto cleanup;
 300
 301                mode = inode->i_mode;
 302                error = posix_acl_create_masq(clone, &mode);
 303                if (error >= 0) {
 304                        inode->i_mode = mode;
 305                        if (error > 0) {
 306                                /* This is an extended ACL */
 307                                error = ext3_set_acl(handle, inode,
 308                                                     ACL_TYPE_ACCESS, clone);
 309                        }
 310                }
 311                posix_acl_release(clone);
 312        }
 313cleanup:
 314        posix_acl_release(acl);
 315        return error;
 316}
 317
 318/*
 319 * Does chmod for an inode that may have an Access Control List. The
 320 * inode->i_mode field must be updated to the desired value by the caller
 321 * before calling this function.
 322 * Returns 0 on success, or a negative error number.
 323 *
 324 * We change the ACL rather than storing some ACL entries in the file
 325 * mode permission bits (which would be more efficient), because that
 326 * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 327 * for directories) are added. There are no more bits available in the
 328 * file mode.
 329 *
 330 * inode->i_mutex: down
 331 */
 332int
 333ext3_acl_chmod(struct inode *inode)
 334{
 335        struct posix_acl *acl, *clone;
 336        int error;
 337
 338        if (S_ISLNK(inode->i_mode))
 339                return -EOPNOTSUPP;
 340        if (!test_opt(inode->i_sb, POSIX_ACL))
 341                return 0;
 342        acl = ext3_get_acl(inode, ACL_TYPE_ACCESS);
 343        if (IS_ERR(acl) || !acl)
 344                return PTR_ERR(acl);
 345        clone = posix_acl_clone(acl, GFP_KERNEL);
 346        posix_acl_release(acl);
 347        if (!clone)
 348                return -ENOMEM;
 349        error = posix_acl_chmod_masq(clone, inode->i_mode);
 350        if (!error) {
 351                handle_t *handle;
 352                int retries = 0;
 353
 354        retry:
 355                handle = ext3_journal_start(inode,
 356                                EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 357                if (IS_ERR(handle)) {
 358                        error = PTR_ERR(handle);
 359                        ext3_std_error(inode->i_sb, error);
 360                        goto out;
 361                }
 362                error = ext3_set_acl(handle, inode, ACL_TYPE_ACCESS, clone);
 363                ext3_journal_stop(handle);
 364                if (error == -ENOSPC &&
 365                    ext3_should_retry_alloc(inode->i_sb, &retries))
 366                        goto retry;
 367        }
 368out:
 369        posix_acl_release(clone);
 370        return error;
 371}
 372
 373/*
 374 * Extended attribute handlers
 375 */
 376static size_t
 377ext3_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_len,
 378                           const char *name, size_t name_len, int type)
 379{
 380        const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 381
 382        if (!test_opt(dentry->d_sb, POSIX_ACL))
 383                return 0;
 384        if (list && size <= list_len)
 385                memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 386        return size;
 387}
 388
 389static size_t
 390ext3_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_len,
 391                            const char *name, size_t name_len, int type)
 392{
 393        const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 394
 395        if (!test_opt(dentry->d_sb, POSIX_ACL))
 396                return 0;
 397        if (list && size <= list_len)
 398                memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 399        return size;
 400}
 401
 402static int
 403ext3_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
 404                   size_t size, int type)
 405{
 406        struct posix_acl *acl;
 407        int error;
 408
 409        if (strcmp(name, "") != 0)
 410                return -EINVAL;
 411        if (!test_opt(dentry->d_sb, POSIX_ACL))
 412                return -EOPNOTSUPP;
 413
 414        acl = ext3_get_acl(dentry->d_inode, type);
 415        if (IS_ERR(acl))
 416                return PTR_ERR(acl);
 417        if (acl == NULL)
 418                return -ENODATA;
 419        error = posix_acl_to_xattr(acl, buffer, size);
 420        posix_acl_release(acl);
 421
 422        return error;
 423}
 424
 425static int
 426ext3_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
 427                   size_t size, int flags, int type)
 428{
 429        struct inode *inode = dentry->d_inode;
 430        handle_t *handle;
 431        struct posix_acl *acl;
 432        int error, retries = 0;
 433
 434        if (strcmp(name, "") != 0)
 435                return -EINVAL;
 436        if (!test_opt(inode->i_sb, POSIX_ACL))
 437                return -EOPNOTSUPP;
 438        if (!inode_owner_or_capable(inode))
 439                return -EPERM;
 440
 441        if (value) {
 442                acl = posix_acl_from_xattr(value, size);
 443                if (IS_ERR(acl))
 444                        return PTR_ERR(acl);
 445                else if (acl) {
 446                        error = posix_acl_valid(acl);
 447                        if (error)
 448                                goto release_and_out;
 449                }
 450        } else
 451                acl = NULL;
 452
 453retry:
 454        handle = ext3_journal_start(inode, EXT3_DATA_TRANS_BLOCKS(inode->i_sb));
 455        if (IS_ERR(handle))
 456                return PTR_ERR(handle);
 457        error = ext3_set_acl(handle, inode, type, acl);
 458        ext3_journal_stop(handle);
 459        if (error == -ENOSPC && ext3_should_retry_alloc(inode->i_sb, &retries))
 460                goto retry;
 461
 462release_and_out:
 463        posix_acl_release(acl);
 464        return error;
 465}
 466
 467const struct xattr_handler ext3_xattr_acl_access_handler = {
 468        .prefix = POSIX_ACL_XATTR_ACCESS,
 469        .flags  = ACL_TYPE_ACCESS,
 470        .list   = ext3_xattr_list_acl_access,
 471        .get    = ext3_xattr_get_acl,
 472        .set    = ext3_xattr_set_acl,
 473};
 474
 475const struct xattr_handler ext3_xattr_acl_default_handler = {
 476        .prefix = POSIX_ACL_XATTR_DEFAULT,
 477        .flags  = ACL_TYPE_DEFAULT,
 478        .list   = ext3_xattr_list_acl_default,
 479        .get    = ext3_xattr_get_acl,
 480        .set    = ext3_xattr_set_acl,
 481};
 482