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         const struct xfs_acl    *aclp,
  41         int                     len,
  42         int                     max_entries)
  43 {
  44         struct posix_acl_entry *acl_e;
  45         struct posix_acl *acl;
  46         const struct xfs_acl_entry *ace;
  47         unsigned int count, i;
  48
  49         if (len < sizeof(*aclp))
  50                 return ERR_PTR(-EFSCORRUPTED);
  51         count = be32_to_cpu(aclp->acl_cnt);
  52         if (count > max_entries || XFS_ACL_SIZE(count) != len)
  53                 return ERR_PTR(-EFSCORRUPTED);
  54
  55         acl = posix_acl_alloc(count, GFP_KERNEL);
  56         if (!acl)
  57                 return ERR_PTR(-ENOMEM);
  58
  59         for (i = 0; i < count; i++) {
  60                 acl_e = &acl->a_entries[i];
  61                 ace = &aclp->acl_entry[i];
  62
  63                 /*
  64                  * The tag is 32 bits on disk and 16 bits in core.
  65                  *
  66                  * Because every access to it goes through the core
  67                  * format first this is not a problem.
  68                  */
  69                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  70                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  71
  72                 switch (acl_e->e_tag) {
  73                 case ACL_USER:
  74                         acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
  75                         break;
  76                 case ACL_GROUP:
  77                         acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
  78                         break;
  79                 case ACL_USER_OBJ:
  80                 case ACL_GROUP_OBJ:
  81                 case ACL_MASK:
  82                 case ACL_OTHER:
  83                         break;
  84                 default:
  85                         goto fail;
  86                 }
  87         }
  88         return acl;
  89
  90 fail:
  91         posix_acl_release(acl);
  92         return ERR_PTR(-EINVAL);
  93 }
  94
  95 STATIC void
  96 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  97 {
  98         const struct posix_acl_entry *acl_e;
  99         struct xfs_acl_entry *ace;
 100         int i;
 101
 102         aclp->acl_cnt = cpu_to_be32(acl->a_count);
 103         for (i = 0; i < acl->a_count; i++) {
 104                 ace = &aclp->acl_entry[i];
 105                 acl_e = &acl->a_entries[i];
 106
 107                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
 108                 switch (acl_e->e_tag) {
 109                 case ACL_USER:
 110                         ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
 111                         break;
 112                 case ACL_GROUP:
 113                         ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
 114                         break;
 115                 default:
 116                         ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
 117                         break;
 118                 }
 119
 120                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
 121         }
 122 }
 123
 124 struct posix_acl *
 125 xfs_get_acl(struct inode *inode, int type)
 126 {
 127         struct xfs_inode *ip = XFS_I(inode);
 128         struct posix_acl *acl = NULL;
 129         struct xfs_acl *xfs_acl;
 130         unsigned char *ea_name;
 131         int error;
 132         int len;
 133
 134         trace_xfs_get_acl(ip);
 135
 136         switch (type) {
 137         case ACL_TYPE_ACCESS:
 138                 ea_name = SGI_ACL_FILE;
 139                 break;
 140         case ACL_TYPE_DEFAULT:
 141                 ea_name = SGI_ACL_DEFAULT;
 142                 break;
 143         default:
 144                 BUG();
 145         }
 146
 147         /*
 148          * If we have a cached ACLs value just return it, not need to
 149          * go out to the disk.
 150          */
 151         len = XFS_ACL_MAX_SIZE(ip->i_mount);
 152         xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 153         if (!xfs_acl)
 154                 return ERR_PTR(-ENOMEM);
 155
 156         error = xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
 157                                                         &len, ATTR_ROOT);
 158         if (error) {
 159                 /*
 160                  * If the attribute doesn't exist make sure we have a negative
 161                  * cache entry, for any other error assume it is transient.
 162                  */
 163                 if (error != -ENOATTR)
 164                         acl = ERR_PTR(error);
 165         } else  {
 166                 acl = xfs_acl_from_disk(xfs_acl, len,
 167                                         XFS_ACL_MAX_ENTRIES(ip->i_mount));
 168         }
 169         kmem_free(xfs_acl);
 170         return acl;
 171 }
 172
 173 int
 174 __xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 175 {
 176         struct xfs_inode *ip = XFS_I(inode);
 177         unsigned char *ea_name;
 178         int error;
 179
 180         switch (type) {
 181         case ACL_TYPE_ACCESS:
 182                 ea_name = SGI_ACL_FILE;
 183                 break;
 184         case ACL_TYPE_DEFAULT:
 185                 if (!S_ISDIR(inode->i_mode))
 186                         return acl ? -EACCES : 0;
 187                 ea_name = SGI_ACL_DEFAULT;
 188                 break;
 189         default:
 190                 return -EINVAL;
 191         }
 192
 193         if (acl) {
 194                 struct xfs_acl *xfs_acl;
 195                 int len = XFS_ACL_MAX_SIZE(ip->i_mount);
 196
 197                 xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 198                 if (!xfs_acl)
 199                         return -ENOMEM;
 200
 201                 xfs_acl_to_disk(xfs_acl, acl);
 202
 203                 /* subtract away the unused acl entries */
 204                 len -= sizeof(struct xfs_acl_entry) *
 205                          (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
 206
 207                 error = xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
 208                                 len, ATTR_ROOT);
 209
 210                 kmem_free(xfs_acl);
 211         } else {
 212                 /*
 213                  * A NULL ACL argument means we want to remove the ACL.
 214                  */
 215                 error = xfs_attr_remove(ip, ea_name, ATTR_ROOT);
 216
 217                 /*
 218                  * If the attribute didn't exist to start with that's fine.
 219                  */
 220                 if (error == -ENOATTR)
 221                         error = 0;
 222         }
 223
 224         if (!error)
 225                 set_cached_acl(inode, type, acl);
 226         return error;
 227 }
 228
 229 static int
 230 xfs_set_mode(struct inode *inode, umode_t mode)
 231 {
 232         int error = 0;
 233
 234         if (mode != inode->i_mode) {
 235                 struct iattr iattr;
 236
 237                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
 238                 iattr.ia_mode = mode;
 239                 iattr.ia_ctime = current_time(inode);
 240
 241                 error = xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
 242         }
 243
 244         return error;
 245 }
 246
 247 int
 248 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 249 {
 250         umode_t mode;
 251         bool set_mode = false;
 252         int error = 0;
 253
 254         if (!acl)
 255                 goto set_acl;
 256
 257         error = -E2BIG;
 258         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
 259                 return error;
 260
 261         if (type == ACL_TYPE_ACCESS) {
 262                 error = posix_acl_update_mode(inode, &mode, &acl);
 263                 if (error)
 264                         return error;
 265                 set_mode = true;
 266         }
 267
 268  set_acl:
 269         error =  __xfs_set_acl(inode, acl, type);
 270         if (error)
 271                 return error;
 272
 273         /*
 274          * We set the mode after successfully updating the ACL xattr because the
 275          * xattr update can fail at ENOSPC and we don't want to change the mode
 276          * if the ACL update hasn't been applied.
 277          */
 278         if (set_mode)
 279                 error = xfs_set_mode(inode, mode);
 280
 281         return error;
 282 }