fs/xfs/xfs_acl.c

   1 /*
   2  * Copyright (c) 2008, Christoph Hellwig
   3  * All Rights Reserved.
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it would be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write the Free Software Foundation,
  16  * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17  */
  18 #include "xfs.h"
  19 #include "xfs_format.h"
  20 #include "xfs_log_format.h"
  21 #include "xfs_trans_resv.h"
  22 #include "xfs_mount.h"
  23 #include "xfs_inode.h"
  24 #include "xfs_acl.h"
  25 #include "xfs_attr.h"
  26 #include "xfs_trace.h"
  27 #include <linux/slab.h>
  28 #include <linux/xattr.h>
  29 #include <linux/posix_acl_xattr.h>
  30
  31
  32 /*
  33  * Locking scheme:
  34  *  - all ACL updates are protected by inode->i_mutex, which is taken before
  35  *    calling into this file.
  36  */
  37
  38 STATIC struct posix_acl *
  39 xfs_acl_from_disk(
  40         struct xfs_acl  *aclp,
  41         int             max_entries)
  42 {
  43         struct posix_acl_entry *acl_e;
  44         struct posix_acl *acl;
  45         struct xfs_acl_entry *ace;
  46         unsigned int count, i;
  47
  48         count = be32_to_cpu(aclp->acl_cnt);
  49         if (count > max_entries)
  50                 return ERR_PTR(-EFSCORRUPTED);
  51
  52         acl = posix_acl_alloc(count, GFP_KERNEL);
  53         if (!acl)
  54                 return ERR_PTR(-ENOMEM);
  55
  56         for (i = 0; i < count; i++) {
  57                 acl_e = &acl->a_entries[i];
  58                 ace = &aclp->acl_entry[i];
  59
  60                 /*
  61                  * The tag is 32 bits on disk and 16 bits in core.
  62                  *
  63                  * Because every access to it goes through the core
  64                  * format first this is not a problem.
  65                  */
  66                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  67                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  68
  69                 switch (acl_e->e_tag) {
  70                 case ACL_USER:
  71                         acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
  72                         break;
  73                 case ACL_GROUP:
  74                         acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
  75                         break;
  76                 case ACL_USER_OBJ:
  77                 case ACL_GROUP_OBJ:
  78                 case ACL_MASK:
  79                 case ACL_OTHER:
  80                         break;
  81                 default:
  82                         goto fail;
  83                 }
  84         }
  85         return acl;
  86
  87 fail:
  88         posix_acl_release(acl);
  89         return ERR_PTR(-EINVAL);
  90 }
  91
  92 STATIC void
  93 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  94 {
  95         const struct posix_acl_entry *acl_e;
  96         struct xfs_acl_entry *ace;
  97         int i;
  98
  99         aclp->acl_cnt = cpu_to_be32(acl->a_count);
 100         for (i = 0; i < acl->a_count; i++) {
 101                 ace = &aclp->acl_entry[i];
 102                 acl_e = &acl->a_entries[i];
 103
 104                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
 105                 switch (acl_e->e_tag) {
 106                 case ACL_USER:
 107                         ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
 108                         break;
 109                 case ACL_GROUP:
 110                         ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
 111                         break;
 112                 default:
 113                         ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
 114                         break;
 115                 }
 116
 117                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
 118         }
 119 }
 120
 121 struct posix_acl *
 122 xfs_get_acl(struct inode *inode, int type)
 123 {
 124         struct xfs_inode *ip = XFS_I(inode);
 125         struct posix_acl *acl = NULL;
 126         struct xfs_acl *xfs_acl;
 127         unsigned char *ea_name;
 128         int error;
 129         int len;
 130
 131         trace_xfs_get_acl(ip);
 132
 133         switch (type) {
 134         case ACL_TYPE_ACCESS:
 135                 ea_name = SGI_ACL_FILE;
 136                 break;
 137         case ACL_TYPE_DEFAULT:
 138                 ea_name = SGI_ACL_DEFAULT;
 139                 break;
 140         default:
 141                 BUG();
 142         }
 143
 144         /*
 145          * If we have a cached ACLs value just return it, not need to
 146          * go out to the disk.
 147          */
 148         len = XFS_ACL_MAX_SIZE(ip->i_mount);
 149         xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 150         if (!xfs_acl)
 151                 return ERR_PTR(-ENOMEM);
 152
 153         error = xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
 154                                                         &len, ATTR_ROOT);
 155         if (error) {
 156                 /*
 157                  * If the attribute doesn't exist make sure we have a negative
 158                  * cache entry, for any other error assume it is transient and
 159                  * leave the cache entry as ACL_NOT_CACHED.
 160                  */
 161                 if (error == -ENOATTR)
 162                         goto out_update_cache;
 163                 goto out;
 164         }
 165
 166         acl = xfs_acl_from_disk(xfs_acl, XFS_ACL_MAX_ENTRIES(ip->i_mount));
 167         if (IS_ERR(acl))
 168                 goto out;
 169
 170 out_update_cache:
 171         set_cached_acl(inode, type, acl);
 172 out:
 173         kmem_free(xfs_acl);
 174         return acl;
 175 }
 176
 177 STATIC int
 178 __xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 179 {
 180         struct xfs_inode *ip = XFS_I(inode);
 181         unsigned char *ea_name;
 182         int error;
 183
 184         switch (type) {
 185         case ACL_TYPE_ACCESS:
 186                 ea_name = SGI_ACL_FILE;
 187                 break;
 188         case ACL_TYPE_DEFAULT:
 189                 if (!S_ISDIR(inode->i_mode))
 190                         return acl ? -EACCES : 0;
 191                 ea_name = SGI_ACL_DEFAULT;
 192                 break;
 193         default:
 194                 return -EINVAL;
 195         }
 196
 197         if (acl) {
 198                 struct xfs_acl *xfs_acl;
 199                 int len = XFS_ACL_MAX_SIZE(ip->i_mount);
 200
 201                 xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 202                 if (!xfs_acl)
 203                         return -ENOMEM;
 204
 205                 xfs_acl_to_disk(xfs_acl, acl);
 206
 207                 /* subtract away the unused acl entries */
 208                 len -= sizeof(struct xfs_acl_entry) *
 209                          (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
 210
 211                 error = xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
 212                                 len, ATTR_ROOT);
 213
 214                 kmem_free(xfs_acl);
 215         } else {
 216                 /*
 217                  * A NULL ACL argument means we want to remove the ACL.
 218                  */
 219                 error = xfs_attr_remove(ip, ea_name, ATTR_ROOT);
 220
 221                 /*
 222                  * If the attribute didn't exist to start with that's fine.
 223                  */
 224                 if (error == -ENOATTR)
 225                         error = 0;
 226         }
 227
 228         if (!error)
 229                 set_cached_acl(inode, type, acl);
 230         return error;
 231 }
 232
 233 static int
 234 xfs_set_mode(struct inode *inode, umode_t mode)
 235 {
 236         int error = 0;
 237
 238         if (mode != inode->i_mode) {
 239                 struct iattr iattr;
 240
 241                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
 242                 iattr.ia_mode = mode;
 243                 iattr.ia_ctime = current_fs_time(inode->i_sb);
 244
 245                 error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
 246         }
 247
 248         return error;
 249 }
 250
 251 static int
 252 xfs_acl_exists(struct inode *inode, unsigned char *name)
 253 {
 254         int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
 255
 256         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
 257                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
 258 }
 259
 260 int
 261 posix_acl_access_exists(struct inode *inode)
 262 {
 263         return xfs_acl_exists(inode, SGI_ACL_FILE);
 264 }
 265
 266 int
 267 posix_acl_default_exists(struct inode *inode)
 268 {
 269         if (!S_ISDIR(inode->i_mode))
 270                 return 0;
 271         return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
 272 }
 273
 274 int
 275 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 276 {
 277         int error = 0;
 278
 279         if (!acl)
 280                 goto set_acl;
 281
 282         error = -E2BIG;
 283         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
 284                 return error;
 285
 286         if (type == ACL_TYPE_ACCESS) {
 287                 umode_t mode = inode->i_mode;
 288                 error = posix_acl_equiv_mode(acl, &mode);
 289
 290                 if (error <= 0) {
 291                         acl = NULL;
 292
 293                         if (error < 0)
 294                                 return error;
 295                 }
 296
 297                 error = xfs_set_mode(inode, mode);
 298                 if (error)
 299                         return error;
 300         }
 301
 302  set_acl:
 303         return __xfs_set_acl(inode, type, acl);
 304 }