linux/fs/btrfs/acl.c
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   1/*
   2 * Copyright (C) 2007 Red Hat.  All rights reserved.
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of the GNU General Public
   6 * License v2 as published by the Free Software Foundation.
   7 *
   8 * This program is distributed in the hope that it will be useful,
   9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11 * General Public License for more details.
  12 *
  13 * You should have received a copy of the GNU General Public
  14 * License along with this program; if not, write to the
  15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16 * Boston, MA 021110-1307, USA.
  17 */
  18
  19#include <linux/fs.h>
  20#include <linux/string.h>
  21#include <linux/xattr.h>
  22#include <linux/posix_acl_xattr.h>
  23#include <linux/posix_acl.h>
  24#include <linux/sched.h>
  25#include <linux/slab.h>
  26
  27#include "ctree.h"
  28#include "btrfs_inode.h"
  29#include "xattr.h"
  30
  31struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  32{
  33        int size;
  34        const char *name;
  35        char *value = NULL;
  36        struct posix_acl *acl;
  37
  38        if (!IS_POSIXACL(inode))
  39                return NULL;
  40
  41        acl = get_cached_acl(inode, type);
  42        if (acl != ACL_NOT_CACHED)
  43                return acl;
  44
  45        switch (type) {
  46        case ACL_TYPE_ACCESS:
  47                name = POSIX_ACL_XATTR_ACCESS;
  48                break;
  49        case ACL_TYPE_DEFAULT:
  50                name = POSIX_ACL_XATTR_DEFAULT;
  51                break;
  52        default:
  53                BUG();
  54        }
  55
  56        size = __btrfs_getxattr(inode, name, "", 0);
  57        if (size > 0) {
  58                value = kzalloc(size, GFP_NOFS);
  59                if (!value)
  60                        return ERR_PTR(-ENOMEM);
  61                size = __btrfs_getxattr(inode, name, value, size);
  62        }
  63        if (size > 0) {
  64                acl = posix_acl_from_xattr(value, size);
  65        } else if (size == -ENOENT || size == -ENODATA || size == 0) {
  66                /* FIXME, who returns -ENOENT?  I think nobody */
  67                acl = NULL;
  68        } else {
  69                acl = ERR_PTR(-EIO);
  70        }
  71        kfree(value);
  72
  73        if (!IS_ERR(acl))
  74                set_cached_acl(inode, type, acl);
  75
  76        return acl;
  77}
  78
  79static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
  80                void *value, size_t size, int type)
  81{
  82        struct posix_acl *acl;
  83        int ret = 0;
  84
  85        if (!IS_POSIXACL(dentry->d_inode))
  86                return -EOPNOTSUPP;
  87
  88        acl = btrfs_get_acl(dentry->d_inode, type);
  89
  90        if (IS_ERR(acl))
  91                return PTR_ERR(acl);
  92        if (acl == NULL)
  93                return -ENODATA;
  94        ret = posix_acl_to_xattr(acl, value, size);
  95        posix_acl_release(acl);
  96
  97        return ret;
  98}
  99
 100/*
 101 * Needs to be called with fs_mutex held
 102 */
 103static int btrfs_set_acl(struct btrfs_trans_handle *trans,
 104                         struct inode *inode, struct posix_acl *acl, int type)
 105{
 106        int ret, size = 0;
 107        const char *name;
 108        char *value = NULL;
 109
 110        if (acl) {
 111                ret = posix_acl_valid(acl);
 112                if (ret < 0)
 113                        return ret;
 114                ret = 0;
 115        }
 116
 117        switch (type) {
 118        case ACL_TYPE_ACCESS:
 119                name = POSIX_ACL_XATTR_ACCESS;
 120                if (acl) {
 121                        ret = posix_acl_equiv_mode(acl, &inode->i_mode);
 122                        if (ret < 0)
 123                                return ret;
 124                }
 125                ret = 0;
 126                break;
 127        case ACL_TYPE_DEFAULT:
 128                if (!S_ISDIR(inode->i_mode))
 129                        return acl ? -EINVAL : 0;
 130                name = POSIX_ACL_XATTR_DEFAULT;
 131                break;
 132        default:
 133                return -EINVAL;
 134        }
 135
 136        if (acl) {
 137                size = posix_acl_xattr_size(acl->a_count);
 138                value = kmalloc(size, GFP_NOFS);
 139                if (!value) {
 140                        ret = -ENOMEM;
 141                        goto out;
 142                }
 143
 144                ret = posix_acl_to_xattr(acl, value, size);
 145                if (ret < 0)
 146                        goto out;
 147        }
 148
 149        ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 150out:
 151        kfree(value);
 152
 153        if (!ret)
 154                set_cached_acl(inode, type, acl);
 155
 156        return ret;
 157}
 158
 159static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 160                const void *value, size_t size, int flags, int type)
 161{
 162        int ret;
 163        struct posix_acl *acl = NULL;
 164
 165        if (!inode_owner_or_capable(dentry->d_inode))
 166                return -EPERM;
 167
 168        if (!IS_POSIXACL(dentry->d_inode))
 169                return -EOPNOTSUPP;
 170
 171        if (value) {
 172                acl = posix_acl_from_xattr(value, size);
 173                if (IS_ERR(acl))
 174                        return PTR_ERR(acl);
 175
 176                if (acl) {
 177                        ret = posix_acl_valid(acl);
 178                        if (ret)
 179                                goto out;
 180                }
 181        }
 182
 183        ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
 184out:
 185        posix_acl_release(acl);
 186
 187        return ret;
 188}
 189
 190/*
 191 * btrfs_init_acl is already generally called under fs_mutex, so the locking
 192 * stuff has been fixed to work with that.  If the locking stuff changes, we
 193 * need to re-evaluate the acl locking stuff.
 194 */
 195int btrfs_init_acl(struct btrfs_trans_handle *trans,
 196                   struct inode *inode, struct inode *dir)
 197{
 198        struct posix_acl *acl = NULL;
 199        int ret = 0;
 200
 201        /* this happens with subvols */
 202        if (!dir)
 203                return 0;
 204
 205        if (!S_ISLNK(inode->i_mode)) {
 206                if (IS_POSIXACL(dir)) {
 207                        acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 208                        if (IS_ERR(acl))
 209                                return PTR_ERR(acl);
 210                }
 211
 212                if (!acl)
 213                        inode->i_mode &= ~current_umask();
 214        }
 215
 216        if (IS_POSIXACL(dir) && acl) {
 217                if (S_ISDIR(inode->i_mode)) {
 218                        ret = btrfs_set_acl(trans, inode, acl,
 219                                            ACL_TYPE_DEFAULT);
 220                        if (ret)
 221                                goto failed;
 222                }
 223                ret = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);
 224                if (ret < 0)
 225                        return ret;
 226
 227                if (ret > 0) {
 228                        /* we need an acl */
 229                        ret = btrfs_set_acl(trans, inode, acl, ACL_TYPE_ACCESS);
 230                } else {
 231                        cache_no_acl(inode);
 232                }
 233        } else {
 234                cache_no_acl(inode);
 235        }
 236failed:
 237        posix_acl_release(acl);
 238
 239        return ret;
 240}
 241
 242int btrfs_acl_chmod(struct inode *inode)
 243{
 244        struct posix_acl *acl;
 245        int ret = 0;
 246
 247        if (S_ISLNK(inode->i_mode))
 248                return -EOPNOTSUPP;
 249
 250        if (!IS_POSIXACL(inode))
 251                return 0;
 252
 253        acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 254        if (IS_ERR_OR_NULL(acl))
 255                return PTR_ERR(acl);
 256
 257        ret = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 258        if (ret)
 259                return ret;
 260        ret = btrfs_set_acl(NULL, inode, acl, ACL_TYPE_ACCESS);
 261        posix_acl_release(acl);
 262        return ret;
 263}
 264
 265const struct xattr_handler btrfs_xattr_acl_default_handler = {
 266        .prefix = POSIX_ACL_XATTR_DEFAULT,
 267        .flags  = ACL_TYPE_DEFAULT,
 268        .get    = btrfs_xattr_acl_get,
 269        .set    = btrfs_xattr_acl_set,
 270};
 271
 272const struct xattr_handler btrfs_xattr_acl_access_handler = {
 273        .prefix = POSIX_ACL_XATTR_ACCESS,
 274        .flags  = ACL_TYPE_ACCESS,
 275        .get    = btrfs_xattr_acl_get,
 276        .set    = btrfs_xattr_acl_set,
 277};
 278
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