fs/btrfs/acl.c

   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
  31 #ifdef CONFIG_BTRFS_FS_POSIX_ACL
  32
  33 static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  34 {
  35         int size;
  36         const char *name;
  37         char *value = NULL;
  38         struct posix_acl *acl;
  39
  40         acl = get_cached_acl(inode, type);
  41         if (acl != ACL_NOT_CACHED)
  42                 return acl;
  43
  44         switch (type) {
  45         case ACL_TYPE_ACCESS:
  46                 name = POSIX_ACL_XATTR_ACCESS;
  47                 break;
  48         case ACL_TYPE_DEFAULT:
  49                 name = POSIX_ACL_XATTR_DEFAULT;
  50                 break;
  51         default:
  52                 BUG();
  53         }
  54
  55         size = __btrfs_getxattr(inode, name, "", 0);
  56         if (size > 0) {
  57                 value = kzalloc(size, GFP_NOFS);
  58                 if (!value)
  59                         return ERR_PTR(-ENOMEM);
  60                 size = __btrfs_getxattr(inode, name, value, size);
  61                 if (size > 0) {
  62                         acl = posix_acl_from_xattr(value, size);
  63                         if (IS_ERR(acl)) {
  64                                 kfree(value);
  65                                 return acl;
  66                         }
  67                         set_cached_acl(inode, type, acl);
  68                 }
  69                 kfree(value);
  70         } else if (size == -ENOENT || size == -ENODATA || size == 0) {
  71                 /* FIXME, who returns -ENOENT?  I think nobody */
  72                 acl = NULL;
  73                 set_cached_acl(inode, type, acl);
  74         } else {
  75                 acl = ERR_PTR(-EIO);
  76         }
  77
  78         return acl;
  79 }
  80
  81 static int btrfs_xattr_acl_get(struct dentry *dentry, const char *name,
  82                 void *value, size_t size, int type)
  83 {
  84         struct posix_acl *acl;
  85         int ret = 0;
  86
  87         acl = btrfs_get_acl(dentry->d_inode, type);
  88
  89         if (IS_ERR(acl))
  90                 return PTR_ERR(acl);
  91         if (acl == NULL)
  92                 return -ENODATA;
  93         ret = posix_acl_to_xattr(acl, value, size);
  94         posix_acl_release(acl);
  95
  96         return ret;
  97 }
  98
  99 /*
 100  * Needs to be called with fs_mutex held
 101  */
 102 static int btrfs_set_acl(struct btrfs_trans_handle *trans,
 103                          struct inode *inode, struct posix_acl *acl, int type)
 104 {
 105         int ret, size = 0;
 106         const char *name;
 107         char *value = NULL;
 108         mode_t mode;
 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                 mode = inode->i_mode;
 120                 name = POSIX_ACL_XATTR_ACCESS;
 121                 if (acl) {
 122                         ret = posix_acl_equiv_mode(acl, &mode);
 123                         if (ret < 0)
 124                                 return ret;
 125                         inode->i_mode = mode;
 126                 }
 127                 ret = 0;
 128                 break;
 129         case ACL_TYPE_DEFAULT:
 130                 if (!S_ISDIR(inode->i_mode))
 131                         return acl ? -EINVAL : 0;
 132                 name = POSIX_ACL_XATTR_DEFAULT;
 133                 break;
 134         default:
 135                 return -EINVAL;
 136         }
 137
 138         if (acl) {
 139                 size = posix_acl_xattr_size(acl->a_count);
 140                 value = kmalloc(size, GFP_NOFS);
 141                 if (!value) {
 142                         ret = -ENOMEM;
 143                         goto out;
 144                 }
 145
 146                 ret = posix_acl_to_xattr(acl, value, size);
 147                 if (ret < 0)
 148                         goto out;
 149         }
 150
 151         ret = __btrfs_setxattr(trans, inode, name, value, size, 0);
 152 out:
 153         kfree(value);
 154
 155         if (!ret)
 156                 set_cached_acl(inode, type, acl);
 157
 158         return ret;
 159 }
 160
 161 static int btrfs_xattr_acl_set(struct dentry *dentry, const char *name,
 162                 const void *value, size_t size, int flags, int type)
 163 {
 164         int ret;
 165         struct posix_acl *acl = NULL;
 166
 167         if (!is_owner_or_cap(dentry->d_inode))
 168                 return -EPERM;
 169
 170         if (!IS_POSIXACL(dentry->d_inode))
 171                 return -EOPNOTSUPP;
 172
 173         if (value) {
 174                 acl = posix_acl_from_xattr(value, size);
 175                 if (acl == NULL) {
 176                         value = NULL;
 177                         size = 0;
 178                 } else if (IS_ERR(acl)) {
 179                         return PTR_ERR(acl);
 180                 }
 181         }
 182
 183         ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
 184
 185         posix_acl_release(acl);
 186
 187         return ret;
 188 }
 189
 190 int btrfs_check_acl(struct inode *inode, int mask, unsigned int flags)
 191 {
 192         int error = -EAGAIN;
 193
 194         if (flags & IPERM_FLAG_RCU) {
 195                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 196                         error = -ECHILD;
 197
 198         } else {
 199                 struct posix_acl *acl;
 200                 acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 201                 if (IS_ERR(acl))
 202                         return PTR_ERR(acl);
 203                 if (acl) {
 204                         error = posix_acl_permission(inode, acl, mask);
 205                         posix_acl_release(acl);
 206                 }
 207         }
 208
 209         return error;
 210 }
 211
 212 /*
 213  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 214  * stuff has been fixed to work with that.  If the locking stuff changes, we
 215  * need to re-evaluate the acl locking stuff.
 216  */
 217 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 218                    struct inode *inode, struct inode *dir)
 219 {
 220         struct posix_acl *acl = NULL;
 221         int ret = 0;
 222
 223         /* this happens with subvols */
 224         if (!dir)
 225                 return 0;
 226
 227         if (!S_ISLNK(inode->i_mode)) {
 228                 if (IS_POSIXACL(dir)) {
 229                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 230                         if (IS_ERR(acl))
 231                                 return PTR_ERR(acl);
 232                 }
 233
 234                 if (!acl)
 235                         inode->i_mode &= ~current_umask();
 236         }
 237
 238         if (IS_POSIXACL(dir) && acl) {
 239                 struct posix_acl *clone;
 240                 mode_t mode;
 241
 242                 if (S_ISDIR(inode->i_mode)) {
 243                         ret = btrfs_set_acl(trans, inode, acl,
 244                                             ACL_TYPE_DEFAULT);
 245                         if (ret)
 246                                 goto failed;
 247                 }
 248                 clone = posix_acl_clone(acl, GFP_NOFS);
 249                 ret = -ENOMEM;
 250                 if (!clone)
 251                         goto failed;
 252
 253                 mode = inode->i_mode;
 254                 ret = posix_acl_create_masq(clone, &mode);
 255                 if (ret >= 0) {
 256                         inode->i_mode = mode;
 257                         if (ret > 0) {
 258                                 /* we need an acl */
 259                                 ret = btrfs_set_acl(trans, inode, clone,
 260                                                     ACL_TYPE_ACCESS);
 261                         }
 262                 }
 263                 posix_acl_release(clone);
 264         }
 265 failed:
 266         posix_acl_release(acl);
 267
 268         return ret;
 269 }
 270
 271 int btrfs_acl_chmod(struct inode *inode)
 272 {
 273         struct posix_acl *acl, *clone;
 274         int ret = 0;
 275
 276         if (S_ISLNK(inode->i_mode))
 277                 return -EOPNOTSUPP;
 278
 279         if (!IS_POSIXACL(inode))
 280                 return 0;
 281
 282         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 283         if (IS_ERR(acl) || !acl)
 284                 return PTR_ERR(acl);
 285
 286         clone = posix_acl_clone(acl, GFP_KERNEL);
 287         posix_acl_release(acl);
 288         if (!clone)
 289                 return -ENOMEM;
 290
 291         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 292         if (!ret)
 293                 ret = btrfs_set_acl(NULL, inode, clone, ACL_TYPE_ACCESS);
 294
 295         posix_acl_release(clone);
 296
 297         return ret;
 298 }
 299
 300 const struct xattr_handler btrfs_xattr_acl_default_handler = {
 301         .prefix = POSIX_ACL_XATTR_DEFAULT,
 302         .flags  = ACL_TYPE_DEFAULT,
 303         .get    = btrfs_xattr_acl_get,
 304         .set    = btrfs_xattr_acl_set,
 305 };
 306
 307 const struct xattr_handler btrfs_xattr_acl_access_handler = {
 308         .prefix = POSIX_ACL_XATTR_ACCESS,
 309         .flags  = ACL_TYPE_ACCESS,
 310         .get    = btrfs_xattr_acl_get,
 311         .set    = btrfs_xattr_acl_set,
 312 };
 313
 314 #else /* CONFIG_BTRFS_FS_POSIX_ACL */
 315
 316 int btrfs_acl_chmod(struct inode *inode)
 317 {
 318         return 0;
 319 }
 320
 321 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 322                    struct inode *inode, struct inode *dir)
 323 {
 324         return 0;
 325 }
 326
 327 #endif /* CONFIG_BTRFS_FS_POSIX_ACL */