linux/fs/ext2/acl.c
<<
>>
Prefs
   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 */
  19static struct posix_acl *
  20ext2_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
  76fail:
  77        posix_acl_release(acl);
  78        return ERR_PTR(-EINVAL);
  79}
  80
  81/*
  82 * Convert from in-memory to filesystem representation.
  83 */
  84static void *
  85ext2_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
 123fail:
 124        kfree(ext_acl);
 125        return ERR_PTR(-EINVAL);
 126}
 127
 128static inline struct posix_acl *
 129ext2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
 130{
 131        struct posix_acl *acl = EXT2_ACL_NOT_CACHED;
 132
 133        spin_lock(&inode->i_lock);
 134        if (*i_acl != EXT2_ACL_NOT_CACHED)
 135                acl = posix_acl_dup(*i_acl);
 136        spin_unlock(&inode->i_lock);
 137
 138        return acl;
 139}
 140
 141static inline void
 142ext2_iset_acl(struct inode *inode, struct posix_acl **i_acl,
 143                   struct posix_acl *acl)
 144{
 145        spin_lock(&inode->i_lock);
 146        if (*i_acl != EXT2_ACL_NOT_CACHED)
 147                posix_acl_release(*i_acl);
 148        *i_acl = posix_acl_dup(acl);
 149        spin_unlock(&inode->i_lock);
 150}
 151
 152/*
 153 * inode->i_mutex: don't care
 154 */
 155static struct posix_acl *
 156ext2_get_acl(struct inode *inode, int type)
 157{
 158        struct ext2_inode_info *ei = EXT2_I(inode);
 159        int name_index;
 160        char *value = NULL;
 161        struct posix_acl *acl;
 162        int retval;
 163
 164        if (!test_opt(inode->i_sb, POSIX_ACL))
 165                return NULL;
 166
 167        switch(type) {
 168                case ACL_TYPE_ACCESS:
 169                        acl = ext2_iget_acl(inode, &ei->i_acl);
 170                        if (acl != EXT2_ACL_NOT_CACHED)
 171                                return acl;
 172                        name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 173                        break;
 174
 175                case ACL_TYPE_DEFAULT:
 176                        acl = ext2_iget_acl(inode, &ei->i_default_acl);
 177                        if (acl != EXT2_ACL_NOT_CACHED)
 178                                return acl;
 179                        name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 180                        break;
 181
 182                default:
 183                        return ERR_PTR(-EINVAL);
 184        }
 185        retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
 186        if (retval > 0) {
 187                value = kmalloc(retval, GFP_KERNEL);
 188                if (!value)
 189                        return ERR_PTR(-ENOMEM);
 190                retval = ext2_xattr_get(inode, name_index, "", value, retval);
 191        }
 192        if (retval > 0)
 193                acl = ext2_acl_from_disk(value, retval);
 194        else if (retval == -ENODATA || retval == -ENOSYS)
 195                acl = NULL;
 196        else
 197                acl = ERR_PTR(retval);
 198        kfree(value);
 199
 200        if (!IS_ERR(acl)) {
 201                switch(type) {
 202                        case ACL_TYPE_ACCESS:
 203                                ext2_iset_acl(inode, &ei->i_acl, acl);
 204                                break;
 205
 206                        case ACL_TYPE_DEFAULT:
 207                                ext2_iset_acl(inode, &ei->i_default_acl, acl);
 208                                break;
 209                }
 210        }
 211        return acl;
 212}
 213
 214/*
 215 * inode->i_mutex: down
 216 */
 217static int
 218ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 219{
 220        struct ext2_inode_info *ei = EXT2_I(inode);
 221        int name_index;
 222        void *value = NULL;
 223        size_t size = 0;
 224        int error;
 225
 226        if (S_ISLNK(inode->i_mode))
 227                return -EOPNOTSUPP;
 228        if (!test_opt(inode->i_sb, POSIX_ACL))
 229                return 0;
 230
 231        switch(type) {
 232                case ACL_TYPE_ACCESS:
 233                        name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
 234                        if (acl) {
 235                                mode_t mode = inode->i_mode;
 236                                error = posix_acl_equiv_mode(acl, &mode);
 237                                if (error < 0)
 238                                        return error;
 239                                else {
 240                                        inode->i_mode = mode;
 241                                        mark_inode_dirty(inode);
 242                                        if (error == 0)
 243                                                acl = NULL;
 244                                }
 245                        }
 246                        break;
 247
 248                case ACL_TYPE_DEFAULT:
 249                        name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
 250                        if (!S_ISDIR(inode->i_mode))
 251                                return acl ? -EACCES : 0;
 252                        break;
 253
 254                default:
 255                        return -EINVAL;
 256        }
 257        if (acl) {
 258                value = ext2_acl_to_disk(acl, &size);
 259                if (IS_ERR(value))
 260                        return (int)PTR_ERR(value);
 261        }
 262
 263        error = ext2_xattr_set(inode, name_index, "", value, size, 0);
 264
 265        kfree(value);
 266        if (!error) {
 267                switch(type) {
 268                        case ACL_TYPE_ACCESS:
 269                                ext2_iset_acl(inode, &ei->i_acl, acl);
 270                                break;
 271
 272                        case ACL_TYPE_DEFAULT:
 273                                ext2_iset_acl(inode, &ei->i_default_acl, acl);
 274                                break;
 275                }
 276        }
 277        return error;
 278}
 279
 280static int
 281ext2_check_acl(struct inode *inode, int mask)
 282{
 283        struct posix_acl *acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 284
 285        if (IS_ERR(acl))
 286                return PTR_ERR(acl);
 287        if (acl) {
 288                int error = posix_acl_permission(inode, acl, mask);
 289                posix_acl_release(acl);
 290                return error;
 291        }
 292
 293        return -EAGAIN;
 294}
 295
 296int
 297ext2_permission(struct inode *inode, int mask, struct nameidata *nd)
 298{
 299        return generic_permission(inode, mask, ext2_check_acl);
 300}
 301
 302/*
 303 * Initialize the ACLs of a new inode. Called from ext2_new_inode.
 304 *
 305 * dir->i_mutex: down
 306 * inode->i_mutex: up (access to inode is still exclusive)
 307 */
 308int
 309ext2_init_acl(struct inode *inode, struct inode *dir)
 310{
 311        struct posix_acl *acl = NULL;
 312        int error = 0;
 313
 314        if (!S_ISLNK(inode->i_mode)) {
 315                if (test_opt(dir->i_sb, POSIX_ACL)) {
 316                        acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
 317                        if (IS_ERR(acl))
 318                                return PTR_ERR(acl);
 319                }
 320                if (!acl)
 321                        inode->i_mode &= ~current->fs->umask;
 322        }
 323        if (test_opt(inode->i_sb, POSIX_ACL) && acl) {
 324               struct posix_acl *clone;
 325               mode_t mode;
 326
 327                if (S_ISDIR(inode->i_mode)) {
 328                        error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 329                        if (error)
 330                                goto cleanup;
 331                }
 332                clone = posix_acl_clone(acl, GFP_KERNEL);
 333                error = -ENOMEM;
 334                if (!clone)
 335                        goto cleanup;
 336                mode = inode->i_mode;
 337                error = posix_acl_create_masq(clone, &mode);
 338                if (error >= 0) {
 339                        inode->i_mode = mode;
 340                        if (error > 0) {
 341                                /* This is an extended ACL */
 342                                error = ext2_set_acl(inode,
 343                                                     ACL_TYPE_ACCESS, clone);
 344                        }
 345                }
 346                posix_acl_release(clone);
 347        }
 348cleanup:
 349       posix_acl_release(acl);
 350       return error;
 351}
 352
 353/*
 354 * Does chmod for an inode that may have an Access Control List. The
 355 * inode->i_mode field must be updated to the desired value by the caller
 356 * before calling this function.
 357 * Returns 0 on success, or a negative error number.
 358 *
 359 * We change the ACL rather than storing some ACL entries in the file
 360 * mode permission bits (which would be more efficient), because that
 361 * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
 362 * for directories) are added. There are no more bits available in the
 363 * file mode.
 364 *
 365 * inode->i_mutex: down
 366 */
 367int
 368ext2_acl_chmod(struct inode *inode)
 369{
 370        struct posix_acl *acl, *clone;
 371        int error;
 372
 373        if (!test_opt(inode->i_sb, POSIX_ACL))
 374                return 0;
 375        if (S_ISLNK(inode->i_mode))
 376                return -EOPNOTSUPP;
 377        acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
 378        if (IS_ERR(acl) || !acl)
 379                return PTR_ERR(acl);
 380        clone = posix_acl_clone(acl, GFP_KERNEL);
 381        posix_acl_release(acl);
 382        if (!clone)
 383                return -ENOMEM;
 384        error = posix_acl_chmod_masq(clone, inode->i_mode);
 385        if (!error)
 386                error = ext2_set_acl(inode, ACL_TYPE_ACCESS, clone);
 387        posix_acl_release(clone);
 388        return error;
 389}
 390
 391/*
 392 * Extended attribut handlers
 393 */
 394static size_t
 395ext2_xattr_list_acl_access(struct inode *inode, char *list, size_t list_size,
 396                           const char *name, size_t name_len)
 397{
 398        const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);
 399
 400        if (!test_opt(inode->i_sb, POSIX_ACL))
 401                return 0;
 402        if (list && size <= list_size)
 403                memcpy(list, POSIX_ACL_XATTR_ACCESS, size);
 404        return size;
 405}
 406
 407static size_t
 408ext2_xattr_list_acl_default(struct inode *inode, char *list, size_t list_size,
 409                            const char *name, size_t name_len)
 410{
 411        const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);
 412
 413        if (!test_opt(inode->i_sb, POSIX_ACL))
 414                return 0;
 415        if (list && size <= list_size)
 416                memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);
 417        return size;
 418}
 419
 420static int
 421ext2_xattr_get_acl(struct inode *inode, int type, void *buffer, size_t size)
 422{
 423        struct posix_acl *acl;
 424        int error;
 425
 426        if (!test_opt(inode->i_sb, POSIX_ACL))
 427                return -EOPNOTSUPP;
 428
 429        acl = ext2_get_acl(inode, type);
 430        if (IS_ERR(acl))
 431                return PTR_ERR(acl);
 432        if (acl == NULL)
 433                return -ENODATA;
 434        error = posix_acl_to_xattr(acl, buffer, size);
 435        posix_acl_release(acl);
 436
 437        return error;
 438}
 439
 440static int
 441ext2_xattr_get_acl_access(struct inode *inode, const char *name,
 442                          void *buffer, size_t size)
 443{
 444        if (strcmp(name, "") != 0)
 445                return -EINVAL;
 446        return ext2_xattr_get_acl(inode, ACL_TYPE_ACCESS, buffer, size);
 447}
 448
 449static int
 450ext2_xattr_get_acl_default(struct inode *inode, const char *name,
 451                           void *buffer, size_t size)
 452{
 453        if (strcmp(name, "") != 0)
 454                return -EINVAL;
 455        return ext2_xattr_get_acl(inode, ACL_TYPE_DEFAULT, buffer, size);
 456}
 457
 458static int
 459ext2_xattr_set_acl(struct inode *inode, int type, const void *value,
 460                   size_t size)
 461{
 462        struct posix_acl *acl;
 463        int error;
 464
 465        if (!test_opt(inode->i_sb, POSIX_ACL))
 466                return -EOPNOTSUPP;
 467        if (!is_owner_or_cap(inode))
 468                return -EPERM;
 469
 470        if (value) {
 471                acl = posix_acl_from_xattr(value, size);
 472                if (IS_ERR(acl))
 473                        return PTR_ERR(acl);
 474                else if (acl) {
 475                        error = posix_acl_valid(acl);
 476                        if (error)
 477                                goto release_and_out;
 478                }
 479        } else
 480                acl = NULL;
 481
 482        error = ext2_set_acl(inode, type, acl);
 483
 484release_and_out:
 485        posix_acl_release(acl);
 486        return error;
 487}
 488
 489static int
 490ext2_xattr_set_acl_access(struct inode *inode, const char *name,
 491                          const void *value, size_t size, int flags)
 492{
 493        if (strcmp(name, "") != 0)
 494                return -EINVAL;
 495        return ext2_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 496}
 497
 498static int
 499ext2_xattr_set_acl_default(struct inode *inode, const char *name,
 500                           const void *value, size_t size, int flags)
 501{
 502        if (strcmp(name, "") != 0)
 503                return -EINVAL;
 504        return ext2_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 505}
 506
 507struct xattr_handler ext2_xattr_acl_access_handler = {
 508        .prefix = POSIX_ACL_XATTR_ACCESS,
 509        .list   = ext2_xattr_list_acl_access,
 510        .get    = ext2_xattr_get_acl_access,
 511        .set    = ext2_xattr_set_acl_access,
 512};
 513
 514struct xattr_handler ext2_xattr_acl_default_handler = {
 515        .prefix = POSIX_ACL_XATTR_DEFAULT,
 516        .list   = ext2_xattr_list_acl_default,
 517        .get    = ext2_xattr_get_acl_default,
 518        .set    = ext2_xattr_set_acl_default,
 519};
 520