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_ag.h"
  23 #include "xfs_sb.h"
  24 #include "xfs_mount.h"
  25 #include "xfs_inode.h"
  26 #include "xfs_acl.h"
  27 #include "xfs_attr.h"
  28 #include "xfs_trace.h"
  29 #include <linux/slab.h>
  30 #include <linux/xattr.h>
  31 #include <linux/posix_acl_xattr.h>
  32
  33
  34 /*
  35  * Locking scheme:
  36  *  - all ACL updates are protected by inode->i_mutex, which is taken before
  37  *    calling into this file.
  38  */
  39
  40 STATIC struct posix_acl *
  41 xfs_acl_from_disk(
  42         struct xfs_acl  *aclp,
  43         int             max_entries)
  44 {
  45         struct posix_acl_entry *acl_e;
  46         struct posix_acl *acl;
  47         struct xfs_acl_entry *ace;
  48         unsigned int count, i;
  49
  50         count = be32_to_cpu(aclp->acl_cnt);
  51         if (count > max_entries)
  52                 return ERR_PTR(-EFSCORRUPTED);
  53
  54         acl = posix_acl_alloc(count, GFP_KERNEL);
  55         if (!acl)
  56                 return ERR_PTR(-ENOMEM);
  57
  58         for (i = 0; i < count; i++) {
  59                 acl_e = &acl->a_entries[i];
  60                 ace = &aclp->acl_entry[i];
  61
  62                 /*
  63                  * The tag is 32 bits on disk and 16 bits in core.
  64                  *
  65                  * Because every access to it goes through the core
  66                  * format first this is not a problem.
  67                  */
  68                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  69                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  70
  71                 switch (acl_e->e_tag) {
  72                 case ACL_USER:
  73                         acl_e->e_uid = xfs_uid_to_kuid(be32_to_cpu(ace->ae_id));
  74                         break;
  75                 case ACL_GROUP:
  76                         acl_e->e_gid = xfs_gid_to_kgid(be32_to_cpu(ace->ae_id));
  77                         break;
  78                 case ACL_USER_OBJ:
  79                 case ACL_GROUP_OBJ:
  80                 case ACL_MASK:
  81                 case ACL_OTHER:
  82                         break;
  83                 default:
  84                         goto fail;
  85                 }
  86         }
  87         return acl;
  88
  89 fail:
  90         posix_acl_release(acl);
  91         return ERR_PTR(-EINVAL);
  92 }
  93
  94 STATIC void
  95 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  96 {
  97         const struct posix_acl_entry *acl_e;
  98         struct xfs_acl_entry *ace;
  99         int i;
 100
 101         aclp->acl_cnt = cpu_to_be32(acl->a_count);
 102         for (i = 0; i < acl->a_count; i++) {
 103                 ace = &aclp->acl_entry[i];
 104                 acl_e = &acl->a_entries[i];
 105
 106                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
 107                 switch (acl_e->e_tag) {
 108                 case ACL_USER:
 109                         ace->ae_id = cpu_to_be32(xfs_kuid_to_uid(acl_e->e_uid));
 110                         break;
 111                 case ACL_GROUP:
 112                         ace->ae_id = cpu_to_be32(xfs_kgid_to_gid(acl_e->e_gid));
 113                         break;
 114                 default:
 115                         ace->ae_id = cpu_to_be32(ACL_UNDEFINED_ID);
 116                         break;
 117                 }
 118
 119                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
 120         }
 121 }
 122
 123 struct posix_acl *
 124 xfs_get_acl(struct inode *inode, int type)
 125 {
 126         struct xfs_inode *ip = XFS_I(inode);
 127         struct posix_acl *acl = NULL;
 128         struct xfs_acl *xfs_acl;
 129         unsigned char *ea_name;
 130         int error;
 131         int len;
 132
 133         trace_xfs_get_acl(ip);
 134
 135         switch (type) {
 136         case ACL_TYPE_ACCESS:
 137                 ea_name = SGI_ACL_FILE;
 138                 break;
 139         case ACL_TYPE_DEFAULT:
 140                 ea_name = SGI_ACL_DEFAULT;
 141                 break;
 142         default:
 143                 BUG();
 144         }
 145
 146         /*
 147          * If we have a cached ACLs value just return it, not need to
 148          * go out to the disk.
 149          */
 150         len = XFS_ACL_MAX_SIZE(ip->i_mount);
 151         xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 152         if (!xfs_acl)
 153                 return ERR_PTR(-ENOMEM);
 154
 155         error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
 156                                                         &len, ATTR_ROOT);
 157         if (error) {
 158                 /*
 159                  * If the attribute doesn't exist make sure we have a negative
 160                  * cache entry, for any other error assume it is transient and
 161                  * leave the cache entry as ACL_NOT_CACHED.
 162                  */
 163                 if (error == -ENOATTR)
 164                         goto out_update_cache;
 165                 goto out;
 166         }
 167
 168         acl = xfs_acl_from_disk(xfs_acl, XFS_ACL_MAX_ENTRIES(ip->i_mount));
 169         if (IS_ERR(acl))
 170                 goto out;
 171
 172 out_update_cache:
 173         set_cached_acl(inode, type, acl);
 174 out:
 175         kmem_free(xfs_acl);
 176         return acl;
 177 }
 178
 179 STATIC int
 180 __xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 181 {
 182         struct xfs_inode *ip = XFS_I(inode);
 183         unsigned char *ea_name;
 184         int error;
 185
 186         switch (type) {
 187         case ACL_TYPE_ACCESS:
 188                 ea_name = SGI_ACL_FILE;
 189                 break;
 190         case ACL_TYPE_DEFAULT:
 191                 if (!S_ISDIR(inode->i_mode))
 192                         return acl ? -EACCES : 0;
 193                 ea_name = SGI_ACL_DEFAULT;
 194                 break;
 195         default:
 196                 return -EINVAL;
 197         }
 198
 199         if (acl) {
 200                 struct xfs_acl *xfs_acl;
 201                 int len = XFS_ACL_MAX_SIZE(ip->i_mount);
 202
 203                 xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 204                 if (!xfs_acl)
 205                         return -ENOMEM;
 206
 207                 xfs_acl_to_disk(xfs_acl, acl);
 208
 209                 /* subtract away the unused acl entries */
 210                 len -= sizeof(struct xfs_acl_entry) *
 211                          (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
 212
 213                 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
 214                                 len, ATTR_ROOT);
 215
 216                 kmem_free(xfs_acl);
 217         } else {
 218                 /*
 219                  * A NULL ACL argument means we want to remove the ACL.
 220                  */
 221                 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
 222
 223                 /*
 224                  * If the attribute didn't exist to start with that's fine.
 225                  */
 226                 if (error == -ENOATTR)
 227                         error = 0;
 228         }
 229
 230         if (!error)
 231                 set_cached_acl(inode, type, acl);
 232         return error;
 233 }
 234
 235 static int
 236 xfs_set_mode(struct inode *inode, umode_t mode)
 237 {
 238         int error = 0;
 239
 240         if (mode != inode->i_mode) {
 241                 struct iattr iattr;
 242
 243                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
 244                 iattr.ia_mode = mode;
 245                 iattr.ia_ctime = current_fs_time(inode->i_sb);
 246
 247                 error = -xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
 248         }
 249
 250         return error;
 251 }
 252
 253 static int
 254 xfs_acl_exists(struct inode *inode, unsigned char *name)
 255 {
 256         int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
 257
 258         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
 259                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
 260 }
 261
 262 int
 263 posix_acl_access_exists(struct inode *inode)
 264 {
 265         return xfs_acl_exists(inode, SGI_ACL_FILE);
 266 }
 267
 268 int
 269 posix_acl_default_exists(struct inode *inode)
 270 {
 271         if (!S_ISDIR(inode->i_mode))
 272                 return 0;
 273         return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
 274 }
 275
 276 int
 277 xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
 278 {
 279         int error = 0;
 280
 281         if (!acl)
 282                 goto set_acl;
 283
 284         error = -E2BIG;
 285         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
 286                 return error;
 287
 288         if (type == ACL_TYPE_ACCESS) {
 289                 umode_t mode = inode->i_mode;
 290                 error = posix_acl_equiv_mode(acl, &mode);
 291
 292                 if (error <= 0) {
 293                         acl = NULL;
 294
 295                         if (error < 0)
 296                                 return error;
 297                 }
 298
 299                 error = xfs_set_mode(inode, mode);
 300                 if (error)
 301                         return error;
 302         }
 303
 304  set_acl:
 305         return __xfs_set_acl(inode, type, acl);
 306 }