linux/fs/ext2/acl.c
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   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                                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
  83fail:
  84        posix_acl_release(acl);
  85        return ERR_PTR(-EINVAL);
  86}
  87
  88/*
  89 * Convert from in-memory to filesystem representation.
  90 */
  91static void *
  92ext2_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
 135fail:
 136        kfree(ext_acl);
 137        return ERR_PTR(-EINVAL);
 138}
 139
 140/*
 141 * inode->i_mutex: don't care
 142 */
 143struct posix_acl *
 144ext2_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 */
 192static int
 193ext2_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 */
 250int
 251ext2_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        }
 279cleanup:
 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 */
 298int
 299ext2_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 */
 322static size_t
 323ext2_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
 335static size_t
 336ext2_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
 348static int
 349ext2_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
 371static int
 372ext2_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
 399release_and_out:
 400        posix_acl_release(acl);
 401        return error;
 402}
 403
 404const 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
 412const 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};
 419
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