fs/xfs/linux-2.6/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_acl.h"
  20 #include "xfs_attr.h"
  21 #include "xfs_bmap_btree.h"
  22 #include "xfs_inode.h"
  23 #include "xfs_vnodeops.h"
  24 #include "xfs_trace.h"
  25 #include <linux/xattr.h>
  26 #include <linux/posix_acl_xattr.h>
  27
  28
  29 /*
  30  * Locking scheme:
  31  *  - all ACL updates are protected by inode->i_mutex, which is taken before
  32  *    calling into this file.
  33  */
  34
  35 STATIC struct posix_acl *
  36 xfs_acl_from_disk(struct xfs_acl *aclp)
  37 {
  38         struct posix_acl_entry *acl_e;
  39         struct posix_acl *acl;
  40         struct xfs_acl_entry *ace;
  41         int count, i;
  42
  43         count = be32_to_cpu(aclp->acl_cnt);
  44
  45         acl = posix_acl_alloc(count, GFP_KERNEL);
  46         if (!acl)
  47                 return ERR_PTR(-ENOMEM);
  48
  49         for (i = 0; i < count; i++) {
  50                 acl_e = &acl->a_entries[i];
  51                 ace = &aclp->acl_entry[i];
  52
  53                 /*
  54                  * The tag is 32 bits on disk and 16 bits in core.
  55                  *
  56                  * Because every access to it goes through the core
  57                  * format first this is not a problem.
  58                  */
  59                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  60                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  61
  62                 switch (acl_e->e_tag) {
  63                 case ACL_USER:
  64                 case ACL_GROUP:
  65                         acl_e->e_id = be32_to_cpu(ace->ae_id);
  66                         break;
  67                 case ACL_USER_OBJ:
  68                 case ACL_GROUP_OBJ:
  69                 case ACL_MASK:
  70                 case ACL_OTHER:
  71                         acl_e->e_id = ACL_UNDEFINED_ID;
  72                         break;
  73                 default:
  74                         goto fail;
  75                 }
  76         }
  77         return acl;
  78
  79 fail:
  80         posix_acl_release(acl);
  81         return ERR_PTR(-EINVAL);
  82 }
  83
  84 STATIC void
  85 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  86 {
  87         const struct posix_acl_entry *acl_e;
  88         struct xfs_acl_entry *ace;
  89         int i;
  90
  91         aclp->acl_cnt = cpu_to_be32(acl->a_count);
  92         for (i = 0; i < acl->a_count; i++) {
  93                 ace = &aclp->acl_entry[i];
  94                 acl_e = &acl->a_entries[i];
  95
  96                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
  97                 ace->ae_id = cpu_to_be32(acl_e->e_id);
  98                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
  99         }
 100 }
 101
 102 struct posix_acl *
 103 xfs_get_acl(struct inode *inode, int type)
 104 {
 105         struct xfs_inode *ip = XFS_I(inode);
 106         struct posix_acl *acl;
 107         struct xfs_acl *xfs_acl;
 108         int len = sizeof(struct xfs_acl);
 109         char *ea_name;
 110         int error;
 111
 112         acl = get_cached_acl(inode, type);
 113         if (acl != ACL_NOT_CACHED)
 114                 return acl;
 115
 116         switch (type) {
 117         case ACL_TYPE_ACCESS:
 118                 ea_name = SGI_ACL_FILE;
 119                 break;
 120         case ACL_TYPE_DEFAULT:
 121                 ea_name = SGI_ACL_DEFAULT;
 122                 break;
 123         default:
 124                 BUG();
 125         }
 126
 127         /*
 128          * If we have a cached ACLs value just return it, not need to
 129          * go out to the disk.
 130          */
 131
 132         xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
 133         if (!xfs_acl)
 134                 return ERR_PTR(-ENOMEM);
 135
 136         error = -xfs_attr_get(ip, ea_name, (char *)xfs_acl, &len, ATTR_ROOT);
 137         if (error) {
 138                 /*
 139                  * If the attribute doesn't exist make sure we have a negative
 140                  * cache entry, for any other error assume it is transient and
 141                  * leave the cache entry as ACL_NOT_CACHED.
 142                  */
 143                 if (error == -ENOATTR) {
 144                         acl = NULL;
 145                         goto out_update_cache;
 146                 }
 147                 goto out;
 148         }
 149
 150         acl = xfs_acl_from_disk(xfs_acl);
 151         if (IS_ERR(acl))
 152                 goto out;
 153
 154  out_update_cache:
 155         set_cached_acl(inode, type, acl);
 156  out:
 157         kfree(xfs_acl);
 158         return acl;
 159 }
 160
 161 STATIC int
 162 xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 163 {
 164         struct xfs_inode *ip = XFS_I(inode);
 165         char *ea_name;
 166         int error;
 167
 168         if (S_ISLNK(inode->i_mode))
 169                 return -EOPNOTSUPP;
 170
 171         switch (type) {
 172         case ACL_TYPE_ACCESS:
 173                 ea_name = SGI_ACL_FILE;
 174                 break;
 175         case ACL_TYPE_DEFAULT:
 176                 if (!S_ISDIR(inode->i_mode))
 177                         return acl ? -EACCES : 0;
 178                 ea_name = SGI_ACL_DEFAULT;
 179                 break;
 180         default:
 181                 return -EINVAL;
 182         }
 183
 184         if (acl) {
 185                 struct xfs_acl *xfs_acl;
 186                 int len;
 187
 188                 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
 189                 if (!xfs_acl)
 190                         return -ENOMEM;
 191
 192                 xfs_acl_to_disk(xfs_acl, acl);
 193                 len = sizeof(struct xfs_acl) -
 194                         (sizeof(struct xfs_acl_entry) *
 195                          (XFS_ACL_MAX_ENTRIES - acl->a_count));
 196
 197                 error = -xfs_attr_set(ip, ea_name, (char *)xfs_acl,
 198                                 len, ATTR_ROOT);
 199
 200                 kfree(xfs_acl);
 201         } else {
 202                 /*
 203                  * A NULL ACL argument means we want to remove the ACL.
 204                  */
 205                 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
 206
 207                 /*
 208                  * If the attribute didn't exist to start with that's fine.
 209                  */
 210                 if (error == -ENOATTR)
 211                         error = 0;
 212         }
 213
 214         if (!error)
 215                 set_cached_acl(inode, type, acl);
 216         return error;
 217 }
 218
 219 int
 220 xfs_check_acl(struct inode *inode, int mask)
 221 {
 222         struct xfs_inode *ip = XFS_I(inode);
 223         struct posix_acl *acl;
 224         int error = -EAGAIN;
 225
 226         xfs_itrace_entry(ip);
 227
 228         /*
 229          * If there is no attribute fork no ACL exists on this inode and
 230          * we can skip the whole exercise.
 231          */
 232         if (!XFS_IFORK_Q(ip))
 233                 return -EAGAIN;
 234
 235         acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
 236         if (IS_ERR(acl))
 237                 return PTR_ERR(acl);
 238         if (acl) {
 239                 error = posix_acl_permission(inode, acl, mask);
 240                 posix_acl_release(acl);
 241         }
 242
 243         return error;
 244 }
 245
 246 static int
 247 xfs_set_mode(struct inode *inode, mode_t mode)
 248 {
 249         int error = 0;
 250
 251         if (mode != inode->i_mode) {
 252                 struct iattr iattr;
 253
 254                 iattr.ia_valid = ATTR_MODE;
 255                 iattr.ia_mode = mode;
 256
 257                 error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
 258         }
 259
 260         return error;
 261 }
 262
 263 static int
 264 xfs_acl_exists(struct inode *inode, char *name)
 265 {
 266         int len = sizeof(struct xfs_acl);
 267
 268         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
 269                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
 270 }
 271
 272 int
 273 posix_acl_access_exists(struct inode *inode)
 274 {
 275         return xfs_acl_exists(inode, SGI_ACL_FILE);
 276 }
 277
 278 int
 279 posix_acl_default_exists(struct inode *inode)
 280 {
 281         if (!S_ISDIR(inode->i_mode))
 282                 return 0;
 283         return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
 284 }
 285
 286 /*
 287  * No need for i_mutex because the inode is not yet exposed to the VFS.
 288  */
 289 int
 290 xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl)
 291 {
 292         struct posix_acl *clone;
 293         mode_t mode;
 294         int error = 0, inherit = 0;
 295
 296         if (S_ISDIR(inode->i_mode)) {
 297                 error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 298                 if (error)
 299                         return error;
 300         }
 301
 302         clone = posix_acl_clone(default_acl, GFP_KERNEL);
 303         if (!clone)
 304                 return -ENOMEM;
 305
 306         mode = inode->i_mode;
 307         error = posix_acl_create_masq(clone, &mode);
 308         if (error < 0)
 309                 goto out_release_clone;
 310
 311         /*
 312          * If posix_acl_create_masq returns a positive value we need to
 313          * inherit a permission that can't be represented using the Unix
 314          * mode bits and we actually need to set an ACL.
 315          */
 316         if (error > 0)
 317                 inherit = 1;
 318
 319         error = xfs_set_mode(inode, mode);
 320         if (error)
 321                 goto out_release_clone;
 322
 323         if (inherit)
 324                 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
 325
 326  out_release_clone:
 327         posix_acl_release(clone);
 328         return error;
 329 }
 330
 331 int
 332 xfs_acl_chmod(struct inode *inode)
 333 {
 334         struct posix_acl *acl, *clone;
 335         int error;
 336
 337         if (S_ISLNK(inode->i_mode))
 338                 return -EOPNOTSUPP;
 339
 340         acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
 341         if (IS_ERR(acl) || !acl)
 342                 return PTR_ERR(acl);
 343
 344         clone = posix_acl_clone(acl, GFP_KERNEL);
 345         posix_acl_release(acl);
 346         if (!clone)
 347                 return -ENOMEM;
 348
 349         error = posix_acl_chmod_masq(clone, inode->i_mode);
 350         if (!error)
 351                 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
 352
 353         posix_acl_release(clone);
 354         return error;
 355 }
 356
 357 static int
 358 xfs_xattr_acl_get(struct dentry *dentry, const char *name,
 359                 void *value, size_t size, int type)
 360 {
 361         struct posix_acl *acl;
 362         int error;
 363
 364         acl = xfs_get_acl(dentry->d_inode, type);
 365         if (IS_ERR(acl))
 366                 return PTR_ERR(acl);
 367         if (acl == NULL)
 368                 return -ENODATA;
 369
 370         error = posix_acl_to_xattr(acl, value, size);
 371         posix_acl_release(acl);
 372
 373         return error;
 374 }
 375
 376 static int
 377 xfs_xattr_acl_set(struct dentry *dentry, const char *name,
 378                 const void *value, size_t size, int flags, int type)
 379 {
 380         struct inode *inode = dentry->d_inode;
 381         struct posix_acl *acl = NULL;
 382         int error = 0;
 383
 384         if (flags & XATTR_CREATE)
 385                 return -EINVAL;
 386         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 387                 return value ? -EACCES : 0;
 388         if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
 389                 return -EPERM;
 390
 391         if (!value)
 392                 goto set_acl;
 393
 394         acl = posix_acl_from_xattr(value, size);
 395         if (!acl) {
 396                 /*
 397                  * acl_set_file(3) may request that we set default ACLs with
 398                  * zero length -- defend (gracefully) against that here.
 399                  */
 400                 goto out;
 401         }
 402         if (IS_ERR(acl)) {
 403                 error = PTR_ERR(acl);
 404                 goto out;
 405         }
 406
 407         error = posix_acl_valid(acl);
 408         if (error)
 409                 goto out_release;
 410
 411         error = -EINVAL;
 412         if (acl->a_count > XFS_ACL_MAX_ENTRIES)
 413                 goto out_release;
 414
 415         if (type == ACL_TYPE_ACCESS) {
 416                 mode_t mode = inode->i_mode;
 417                 error = posix_acl_equiv_mode(acl, &mode);
 418
 419                 if (error <= 0) {
 420                         posix_acl_release(acl);
 421                         acl = NULL;
 422
 423                         if (error < 0)
 424                                 return error;
 425                 }
 426
 427                 error = xfs_set_mode(inode, mode);
 428                 if (error)
 429                         goto out_release;
 430         }
 431
 432  set_acl:
 433         error = xfs_set_acl(inode, type, acl);
 434  out_release:
 435         posix_acl_release(acl);
 436  out:
 437         return error;
 438 }
 439
 440 struct xattr_handler xfs_xattr_acl_access_handler = {
 441         .prefix = POSIX_ACL_XATTR_ACCESS,
 442         .flags  = ACL_TYPE_ACCESS,
 443         .get    = xfs_xattr_acl_get,
 444         .set    = xfs_xattr_acl_set,
 445 };
 446
 447 struct xattr_handler xfs_xattr_acl_default_handler = {
 448         .prefix = POSIX_ACL_XATTR_DEFAULT,
 449         .flags  = ACL_TYPE_DEFAULT,
 450         .get    = xfs_xattr_acl_get,
 451         .set    = xfs_xattr_acl_set,
 452 };