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