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                                 return acl;
  65                         set_cached_acl(inode, type, acl);
  66                 }
  67                 kfree(value);
  68         } else if (size == -ENOENT || size == -ENODATA || size == 0) {
  69                 /* FIXME, who returns -ENOENT?  I think nobody */
  70                 acl = NULL;
  71                 set_cached_acl(inode, type, acl);
  72         } else {
  73                 acl = ERR_PTR(-EIO);
  74         }
  75
  76         return acl;
  77 }
  78
  79 static 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         acl = btrfs_get_acl(dentry->d_inode, type);
  86
  87         if (IS_ERR(acl))
  88                 return PTR_ERR(acl);
  89         if (acl == NULL)
  90                 return -ENODATA;
  91         ret = posix_acl_to_xattr(acl, value, size);
  92         posix_acl_release(acl);
  93
  94         return ret;
  95 }
  96
  97 /*
  98  * Needs to be called with fs_mutex held
  99  */
 100 static int btrfs_set_acl(struct btrfs_trans_handle *trans,
 101                          struct inode *inode, struct posix_acl *acl, int type)
 102 {
 103         int ret, size = 0;
 104         const char *name;
 105         char *value = NULL;
 106         mode_t mode;
 107
 108         if (acl) {
 109                 ret = posix_acl_valid(acl);
 110                 if (ret < 0)
 111                         return ret;
 112                 ret = 0;
 113         }
 114
 115         switch (type) {
 116         case ACL_TYPE_ACCESS:
 117                 mode = inode->i_mode;
 118                 name = POSIX_ACL_XATTR_ACCESS;
 119                 if (acl) {
 120                         ret = posix_acl_equiv_mode(acl, &mode);
 121                         if (ret < 0)
 122                                 return ret;
 123                         inode->i_mode = mode;
 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);
 150 out:
 151         kfree(value);
 152
 153         if (!ret)
 154                 set_cached_acl(inode, type, acl);
 155
 156         return ret;
 157 }
 158
 159 static 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 (!is_owner_or_cap(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 (acl == NULL) {
 174                         value = NULL;
 175                         size = 0;
 176                 } else if (IS_ERR(acl)) {
 177                         return PTR_ERR(acl);
 178                 }
 179         }
 180
 181         ret = btrfs_set_acl(NULL, dentry->d_inode, acl, type);
 182
 183         posix_acl_release(acl);
 184
 185         return ret;
 186 }
 187
 188 int btrfs_check_acl(struct inode *inode, int mask, unsigned int flags)
 189 {
 190         int error = -EAGAIN;
 191
 192         if (flags & IPERM_FLAG_RCU) {
 193                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 194                         error = -ECHILD;
 195
 196         } else {
 197                 struct posix_acl *acl;
 198                 acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 199                 if (IS_ERR(acl))
 200                         return PTR_ERR(acl);
 201                 if (acl) {
 202                         error = posix_acl_permission(inode, acl, mask);
 203                         posix_acl_release(acl);
 204                 }
 205         }
 206
 207         return error;
 208 }
 209
 210 /*
 211  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 212  * stuff has been fixed to work with that.  If the locking stuff changes, we
 213  * need to re-evaluate the acl locking stuff.
 214  */
 215 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 216                    struct inode *inode, struct inode *dir)
 217 {
 218         struct posix_acl *acl = NULL;
 219         int ret = 0;
 220
 221         /* this happens with subvols */
 222         if (!dir)
 223                 return 0;
 224
 225         if (!S_ISLNK(inode->i_mode)) {
 226                 if (IS_POSIXACL(dir)) {
 227                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 228                         if (IS_ERR(acl))
 229                                 return PTR_ERR(acl);
 230                 }
 231
 232                 if (!acl)
 233                         inode->i_mode &= ~current_umask();
 234         }
 235
 236         if (IS_POSIXACL(dir) && acl) {
 237                 struct posix_acl *clone;
 238                 mode_t mode;
 239
 240                 if (S_ISDIR(inode->i_mode)) {
 241                         ret = btrfs_set_acl(trans, inode, acl,
 242                                             ACL_TYPE_DEFAULT);
 243                         if (ret)
 244                                 goto failed;
 245                 }
 246                 clone = posix_acl_clone(acl, GFP_NOFS);
 247                 ret = -ENOMEM;
 248                 if (!clone)
 249                         goto failed;
 250
 251                 mode = inode->i_mode;
 252                 ret = posix_acl_create_masq(clone, &mode);
 253                 if (ret >= 0) {
 254                         inode->i_mode = mode;
 255                         if (ret > 0) {
 256                                 /* we need an acl */
 257                                 ret = btrfs_set_acl(trans, inode, clone,
 258                                                     ACL_TYPE_ACCESS);
 259                         }
 260                 }
 261                 posix_acl_release(clone);
 262         }
 263 failed:
 264         posix_acl_release(acl);
 265
 266         return ret;
 267 }
 268
 269 int btrfs_acl_chmod(struct inode *inode)
 270 {
 271         struct posix_acl *acl, *clone;
 272         int ret = 0;
 273
 274         if (S_ISLNK(inode->i_mode))
 275                 return -EOPNOTSUPP;
 276
 277         if (!IS_POSIXACL(inode))
 278                 return 0;
 279
 280         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 281         if (IS_ERR(acl) || !acl)
 282                 return PTR_ERR(acl);
 283
 284         clone = posix_acl_clone(acl, GFP_KERNEL);
 285         posix_acl_release(acl);
 286         if (!clone)
 287                 return -ENOMEM;
 288
 289         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 290         if (!ret)
 291                 ret = btrfs_set_acl(NULL, inode, clone, ACL_TYPE_ACCESS);
 292
 293         posix_acl_release(clone);
 294
 295         return ret;
 296 }
 297
 298 const struct xattr_handler btrfs_xattr_acl_default_handler = {
 299         .prefix = POSIX_ACL_XATTR_DEFAULT,
 300         .flags  = ACL_TYPE_DEFAULT,
 301         .get    = btrfs_xattr_acl_get,
 302         .set    = btrfs_xattr_acl_set,
 303 };
 304
 305 const struct xattr_handler btrfs_xattr_acl_access_handler = {
 306         .prefix = POSIX_ACL_XATTR_ACCESS,
 307         .flags  = ACL_TYPE_ACCESS,
 308         .get    = btrfs_xattr_acl_get,
 309         .set    = btrfs_xattr_acl_set,
 310 };
 311
 312 #else /* CONFIG_BTRFS_FS_POSIX_ACL */
 313
 314 int btrfs_acl_chmod(struct inode *inode)
 315 {
 316         return 0;
 317 }
 318
 319 int btrfs_init_acl(struct btrfs_trans_handle *trans,
 320                    struct inode *inode, struct inode *dir)
 321 {
 322         return 0;
 323 }
 324
 325 #endif /* CONFIG_BTRFS_FS_POSIX_ACL */