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
  26 #include "ctree.h"
  27 #include "btrfs_inode.h"
  28 #include "xattr.h"
  29
  30 #ifdef CONFIG_FS_POSIX_ACL
  31
  32 static struct posix_acl *btrfs_get_acl(struct inode *inode, int type)
  33 {
  34         int size;
  35         const char *name;
  36         char *value = NULL;
  37         struct posix_acl *acl;
  38
  39         acl = get_cached_acl(inode, type);
  40         if (acl != ACL_NOT_CACHED)
  41                 return acl;
  42
  43         switch (type) {
  44         case ACL_TYPE_ACCESS:
  45                 name = POSIX_ACL_XATTR_ACCESS;
  46                 break;
  47         case ACL_TYPE_DEFAULT:
  48                 name = POSIX_ACL_XATTR_DEFAULT;
  49                 break;
  50         default:
  51                 BUG();
  52         }
  53
  54         size = __btrfs_getxattr(inode, name, "", 0);
  55         if (size > 0) {
  56                 value = kzalloc(size, GFP_NOFS);
  57                 if (!value)
  58                         return ERR_PTR(-ENOMEM);
  59                 size = __btrfs_getxattr(inode, name, value, size);
  60                 if (size > 0) {
  61                         acl = posix_acl_from_xattr(value, size);
  62                         set_cached_acl(inode, type, acl);
  63                 }
  64                 kfree(value);
  65         } else if (size == -ENOENT || size == -ENODATA || size == 0) {
  66                 /* FIXME, who returns -ENOENT?  I think nobody */
  67                 acl = NULL;
  68                 set_cached_acl(inode, type, acl);
  69         } else {
  70                 acl = ERR_PTR(-EIO);
  71         }
  72
  73         return acl;
  74 }
  75
  76 static int btrfs_xattr_get_acl(struct inode *inode, int type,
  77                                void *value, size_t size)
  78 {
  79         struct posix_acl *acl;
  80         int ret = 0;
  81
  82         acl = btrfs_get_acl(inode, type);
  83
  84         if (IS_ERR(acl))
  85                 return PTR_ERR(acl);
  86         if (acl == NULL)
  87                 return -ENODATA;
  88         ret = posix_acl_to_xattr(acl, value, size);
  89         posix_acl_release(acl);
  90
  91         return ret;
  92 }
  93
  94 /*
  95  * Needs to be called with fs_mutex held
  96  */
  97 static int btrfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
  98 {
  99         int ret, size = 0;
 100         const char *name;
 101         char *value = NULL;
 102         mode_t mode;
 103
 104         if (acl) {
 105                 ret = posix_acl_valid(acl);
 106                 if (ret < 0)
 107                         return ret;
 108                 ret = 0;
 109         }
 110
 111         switch (type) {
 112         case ACL_TYPE_ACCESS:
 113                 mode = inode->i_mode;
 114                 ret = posix_acl_equiv_mode(acl, &mode);
 115                 if (ret < 0)
 116                         return ret;
 117                 ret = 0;
 118                 inode->i_mode = mode;
 119                 name = POSIX_ACL_XATTR_ACCESS;
 120                 break;
 121         case ACL_TYPE_DEFAULT:
 122                 if (!S_ISDIR(inode->i_mode))
 123                         return acl ? -EINVAL : 0;
 124                 name = POSIX_ACL_XATTR_DEFAULT;
 125                 break;
 126         default:
 127                 return -EINVAL;
 128         }
 129
 130         if (acl) {
 131                 size = posix_acl_xattr_size(acl->a_count);
 132                 value = kmalloc(size, GFP_NOFS);
 133                 if (!value) {
 134                         ret = -ENOMEM;
 135                         goto out;
 136                 }
 137
 138                 ret = posix_acl_to_xattr(acl, value, size);
 139                 if (ret < 0)
 140                         goto out;
 141         }
 142
 143         ret = __btrfs_setxattr(inode, name, value, size, 0);
 144
 145 out:
 146         kfree(value);
 147
 148         if (!ret)
 149                 set_cached_acl(inode, type, acl);
 150
 151         return ret;
 152 }
 153
 154 static int btrfs_xattr_set_acl(struct inode *inode, int type,
 155                                const void *value, size_t size)
 156 {
 157         int ret = 0;
 158         struct posix_acl *acl = NULL;
 159
 160         if (value) {
 161                 acl = posix_acl_from_xattr(value, size);
 162                 if (acl == NULL) {
 163                         value = NULL;
 164                         size = 0;
 165                 } else if (IS_ERR(acl)) {
 166                         return PTR_ERR(acl);
 167                 }
 168         }
 169
 170         ret = btrfs_set_acl(inode, acl, type);
 171
 172         posix_acl_release(acl);
 173
 174         return ret;
 175 }
 176
 177
 178 static int btrfs_xattr_acl_access_get(struct inode *inode, const char *name,
 179                                       void *value, size_t size)
 180 {
 181         return btrfs_xattr_get_acl(inode, ACL_TYPE_ACCESS, value, size);
 182 }
 183
 184 static int btrfs_xattr_acl_access_set(struct inode *inode, const char *name,
 185                                       const void *value, size_t size, int flags)
 186 {
 187         return btrfs_xattr_set_acl(inode, ACL_TYPE_ACCESS, value, size);
 188 }
 189
 190 static int btrfs_xattr_acl_default_get(struct inode *inode, const char *name,
 191                                        void *value, size_t size)
 192 {
 193         return btrfs_xattr_get_acl(inode, ACL_TYPE_DEFAULT, value, size);
 194 }
 195
 196 static int btrfs_xattr_acl_default_set(struct inode *inode, const char *name,
 197                                const void *value, size_t size, int flags)
 198 {
 199         return btrfs_xattr_set_acl(inode, ACL_TYPE_DEFAULT, value, size);
 200 }
 201
 202 int btrfs_check_acl(struct inode *inode, int mask)
 203 {
 204         struct posix_acl *acl;
 205         int error = -EAGAIN;
 206
 207         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 208
 209         if (IS_ERR(acl))
 210                 return PTR_ERR(acl);
 211         if (acl) {
 212                 error = posix_acl_permission(inode, acl, mask);
 213                 posix_acl_release(acl);
 214         }
 215
 216         return error;
 217 }
 218
 219 /*
 220  * btrfs_init_acl is already generally called under fs_mutex, so the locking
 221  * stuff has been fixed to work with that.  If the locking stuff changes, we
 222  * need to re-evaluate the acl locking stuff.
 223  */
 224 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 225 {
 226         struct posix_acl *acl = NULL;
 227         int ret = 0;
 228
 229         /* this happens with subvols */
 230         if (!dir)
 231                 return 0;
 232
 233         if (!S_ISLNK(inode->i_mode)) {
 234                 if (IS_POSIXACL(dir)) {
 235                         acl = btrfs_get_acl(dir, ACL_TYPE_DEFAULT);
 236                         if (IS_ERR(acl))
 237                                 return PTR_ERR(acl);
 238                 }
 239
 240                 if (!acl)
 241                         inode->i_mode &= ~current_umask();
 242         }
 243
 244         if (IS_POSIXACL(dir) && acl) {
 245                 struct posix_acl *clone;
 246                 mode_t mode;
 247
 248                 if (S_ISDIR(inode->i_mode)) {
 249                         ret = btrfs_set_acl(inode, acl, ACL_TYPE_DEFAULT);
 250                         if (ret)
 251                                 goto failed;
 252                 }
 253                 clone = posix_acl_clone(acl, GFP_NOFS);
 254                 ret = -ENOMEM;
 255                 if (!clone)
 256                         goto failed;
 257
 258                 mode = inode->i_mode;
 259                 ret = posix_acl_create_masq(clone, &mode);
 260                 if (ret >= 0) {
 261                         inode->i_mode = mode;
 262                         if (ret > 0) {
 263                                 /* we need an acl */
 264                                 ret = btrfs_set_acl(inode, clone,
 265                                                     ACL_TYPE_ACCESS);
 266                         }
 267                 }
 268         }
 269 failed:
 270         posix_acl_release(acl);
 271
 272         return ret;
 273 }
 274
 275 int btrfs_acl_chmod(struct inode *inode)
 276 {
 277         struct posix_acl *acl, *clone;
 278         int ret = 0;
 279
 280         if (S_ISLNK(inode->i_mode))
 281                 return -EOPNOTSUPP;
 282
 283         if (!IS_POSIXACL(inode))
 284                 return 0;
 285
 286         acl = btrfs_get_acl(inode, ACL_TYPE_ACCESS);
 287         if (IS_ERR(acl) || !acl)
 288                 return PTR_ERR(acl);
 289
 290         clone = posix_acl_clone(acl, GFP_KERNEL);
 291         posix_acl_release(acl);
 292         if (!clone)
 293                 return -ENOMEM;
 294
 295         ret = posix_acl_chmod_masq(clone, inode->i_mode);
 296         if (!ret)
 297                 ret = btrfs_set_acl(inode, clone, ACL_TYPE_ACCESS);
 298
 299         posix_acl_release(clone);
 300
 301         return ret;
 302 }
 303
 304 struct xattr_handler btrfs_xattr_acl_default_handler = {
 305         .prefix = POSIX_ACL_XATTR_DEFAULT,
 306         .get    = btrfs_xattr_acl_default_get,
 307         .set    = btrfs_xattr_acl_default_set,
 308 };
 309
 310 struct xattr_handler btrfs_xattr_acl_access_handler = {
 311         .prefix = POSIX_ACL_XATTR_ACCESS,
 312         .get    = btrfs_xattr_acl_access_get,
 313         .set    = btrfs_xattr_acl_access_set,
 314 };
 315
 316 #else /* CONFIG_FS_POSIX_ACL */
 317
 318 int btrfs_acl_chmod(struct inode *inode)
 319 {
 320         return 0;
 321 }
 322
 323 int btrfs_init_acl(struct inode *inode, struct inode *dir)
 324 {
 325         return 0;
 326 }
 327
 328 #endif /* CONFIG_FS_POSIX_ACL */