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