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/slab.h>
  26 #include <linux/xattr.h>
  27 #include <linux/posix_acl_xattr.h>
  28
  29
  30 /*
  31  * Locking scheme:
  32  *  - all ACL updates are protected by inode->i_mutex, which is taken before
  33  *    calling into this file.
  34  */
  35
  36 STATIC struct posix_acl *
  37 xfs_acl_from_disk(struct xfs_acl *aclp)
  38 {
  39         struct posix_acl_entry *acl_e;
  40         struct posix_acl *acl;
  41         struct xfs_acl_entry *ace;
  42         int count, i;
  43
  44         count = be32_to_cpu(aclp->acl_cnt);
  45
  46         acl = posix_acl_alloc(count, GFP_KERNEL);
  47         if (!acl)
  48                 return ERR_PTR(-ENOMEM);
  49
  50         for (i = 0; i < count; i++) {
  51                 acl_e = &acl->a_entries[i];
  52                 ace = &aclp->acl_entry[i];
  53
  54                 /*
  55                  * The tag is 32 bits on disk and 16 bits in core.
  56                  *
  57                  * Because every access to it goes through the core
  58                  * format first this is not a problem.
  59                  */
  60                 acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  61                 acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  62
  63                 switch (acl_e->e_tag) {
  64                 case ACL_USER:
  65                 case ACL_GROUP:
  66                         acl_e->e_id = be32_to_cpu(ace->ae_id);
  67                         break;
  68                 case ACL_USER_OBJ:
  69                 case ACL_GROUP_OBJ:
  70                 case ACL_MASK:
  71                 case ACL_OTHER:
  72                         acl_e->e_id = ACL_UNDEFINED_ID;
  73                         break;
  74                 default:
  75                         goto fail;
  76                 }
  77         }
  78         return acl;
  79
  80 fail:
  81         posix_acl_release(acl);
  82         return ERR_PTR(-EINVAL);
  83 }
  84
  85 STATIC void
  86 xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  87 {
  88         const struct posix_acl_entry *acl_e;
  89         struct xfs_acl_entry *ace;
  90         int i;
  91
  92         aclp->acl_cnt = cpu_to_be32(acl->a_count);
  93         for (i = 0; i < acl->a_count; i++) {
  94                 ace = &aclp->acl_entry[i];
  95                 acl_e = &acl->a_entries[i];
  96
  97                 ace->ae_tag = cpu_to_be32(acl_e->e_tag);
  98                 ace->ae_id = cpu_to_be32(acl_e->e_id);
  99                 ace->ae_perm = cpu_to_be16(acl_e->e_perm);
 100         }
 101 }
 102
 103 struct posix_acl *
 104 xfs_get_acl(struct inode *inode, int type)
 105 {
 106         struct xfs_inode *ip = XFS_I(inode);
 107         struct posix_acl *acl;
 108         struct xfs_acl *xfs_acl;
 109         int len = sizeof(struct xfs_acl);
 110         unsigned char *ea_name;
 111         int error;
 112
 113         acl = get_cached_acl(inode, type);
 114         if (acl != ACL_NOT_CACHED)
 115                 return acl;
 116
 117         switch (type) {
 118         case ACL_TYPE_ACCESS:
 119                 ea_name = SGI_ACL_FILE;
 120                 break;
 121         case ACL_TYPE_DEFAULT:
 122                 ea_name = SGI_ACL_DEFAULT;
 123                 break;
 124         default:
 125                 BUG();
 126         }
 127
 128         /*
 129          * If we have a cached ACLs value just return it, not need to
 130          * go out to the disk.
 131          */
 132
 133         xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
 134         if (!xfs_acl)
 135                 return ERR_PTR(-ENOMEM);
 136
 137         error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
 138                                                         &len, ATTR_ROOT);
 139         if (error) {
 140                 /*
 141                  * If the attribute doesn't exist make sure we have a negative
 142                  * cache entry, for any other error assume it is transient and
 143                  * leave the cache entry as ACL_NOT_CACHED.
 144                  */
 145                 if (error == -ENOATTR) {
 146                         acl = NULL;
 147                         goto out_update_cache;
 148                 }
 149                 goto out;
 150         }
 151
 152         acl = xfs_acl_from_disk(xfs_acl);
 153         if (IS_ERR(acl))
 154                 goto out;
 155
 156  out_update_cache:
 157         set_cached_acl(inode, type, acl);
 158  out:
 159         kfree(xfs_acl);
 160         return acl;
 161 }
 162
 163 STATIC int
 164 xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 165 {
 166         struct xfs_inode *ip = XFS_I(inode);
 167         unsigned char *ea_name;
 168         int error;
 169
 170         if (S_ISLNK(inode->i_mode))
 171                 return -EOPNOTSUPP;
 172
 173         switch (type) {
 174         case ACL_TYPE_ACCESS:
 175                 ea_name = SGI_ACL_FILE;
 176                 break;
 177         case ACL_TYPE_DEFAULT:
 178                 if (!S_ISDIR(inode->i_mode))
 179                         return acl ? -EACCES : 0;
 180                 ea_name = SGI_ACL_DEFAULT;
 181                 break;
 182         default:
 183                 return -EINVAL;
 184         }
 185
 186         if (acl) {
 187                 struct xfs_acl *xfs_acl;
 188                 int len;
 189
 190                 xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
 191                 if (!xfs_acl)
 192                         return -ENOMEM;
 193
 194                 xfs_acl_to_disk(xfs_acl, acl);
 195                 len = sizeof(struct xfs_acl) -
 196                         (sizeof(struct xfs_acl_entry) *
 197                          (XFS_ACL_MAX_ENTRIES - acl->a_count));
 198
 199                 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
 200                                 len, ATTR_ROOT);
 201
 202                 kfree(xfs_acl);
 203         } else {
 204                 /*
 205                  * A NULL ACL argument means we want to remove the ACL.
 206                  */
 207                 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
 208
 209                 /*
 210                  * If the attribute didn't exist to start with that's fine.
 211                  */
 212                 if (error == -ENOATTR)
 213                         error = 0;
 214         }
 215
 216         if (!error)
 217                 set_cached_acl(inode, type, acl);
 218         return error;
 219 }
 220
 221 int
 222 xfs_check_acl(struct inode *inode, int mask, unsigned int flags)
 223 {
 224         struct xfs_inode *ip;
 225         struct posix_acl *acl;
 226         int error = -EAGAIN;
 227
 228         ip = XFS_I(inode);
 229         trace_xfs_check_acl(ip);
 230
 231         /*
 232          * If there is no attribute fork no ACL exists on this inode and
 233          * we can skip the whole exercise.
 234          */
 235         if (!XFS_IFORK_Q(ip))
 236                 return -EAGAIN;
 237
 238         if (flags & IPERM_FLAG_RCU) {
 239                 if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
 240                         return -ECHILD;
 241                 return -EAGAIN;
 242         }
 243
 244         acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
 245         if (IS_ERR(acl))
 246                 return PTR_ERR(acl);
 247         if (acl) {
 248                 error = posix_acl_permission(inode, acl, mask);
 249                 posix_acl_release(acl);
 250         }
 251
 252         return error;
 253 }
 254
 255 static int
 256 xfs_set_mode(struct inode *inode, mode_t mode)
 257 {
 258         int error = 0;
 259
 260         if (mode != inode->i_mode) {
 261                 struct iattr iattr;
 262
 263                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
 264                 iattr.ia_mode = mode;
 265                 iattr.ia_ctime = current_fs_time(inode->i_sb);
 266
 267                 error = -xfs_setattr(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
 268         }
 269
 270         return error;
 271 }
 272
 273 static int
 274 xfs_acl_exists(struct inode *inode, unsigned char *name)
 275 {
 276         int len = sizeof(struct xfs_acl);
 277
 278         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
 279                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
 280 }
 281
 282 int
 283 posix_acl_access_exists(struct inode *inode)
 284 {
 285         return xfs_acl_exists(inode, SGI_ACL_FILE);
 286 }
 287
 288 int
 289 posix_acl_default_exists(struct inode *inode)
 290 {
 291         if (!S_ISDIR(inode->i_mode))
 292                 return 0;
 293         return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
 294 }
 295
 296 /*
 297  * No need for i_mutex because the inode is not yet exposed to the VFS.
 298  */
 299 int
 300 xfs_inherit_acl(struct inode *inode, struct posix_acl *default_acl)
 301 {
 302         struct posix_acl *clone;
 303         mode_t mode;
 304         int error = 0, inherit = 0;
 305
 306         if (S_ISDIR(inode->i_mode)) {
 307                 error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl);
 308                 if (error)
 309                         return error;
 310         }
 311
 312         clone = posix_acl_clone(default_acl, GFP_KERNEL);
 313         if (!clone)
 314                 return -ENOMEM;
 315
 316         mode = inode->i_mode;
 317         error = posix_acl_create_masq(clone, &mode);
 318         if (error < 0)
 319                 goto out_release_clone;
 320
 321         /*
 322          * If posix_acl_create_masq returns a positive value we need to
 323          * inherit a permission that can't be represented using the Unix
 324          * mode bits and we actually need to set an ACL.
 325          */
 326         if (error > 0)
 327                 inherit = 1;
 328
 329         error = xfs_set_mode(inode, mode);
 330         if (error)
 331                 goto out_release_clone;
 332
 333         if (inherit)
 334                 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
 335
 336  out_release_clone:
 337         posix_acl_release(clone);
 338         return error;
 339 }
 340
 341 int
 342 xfs_acl_chmod(struct inode *inode)
 343 {
 344         struct posix_acl *acl, *clone;
 345         int error;
 346
 347         if (S_ISLNK(inode->i_mode))
 348                 return -EOPNOTSUPP;
 349
 350         acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
 351         if (IS_ERR(acl) || !acl)
 352                 return PTR_ERR(acl);
 353
 354         clone = posix_acl_clone(acl, GFP_KERNEL);
 355         posix_acl_release(acl);
 356         if (!clone)
 357                 return -ENOMEM;
 358
 359         error = posix_acl_chmod_masq(clone, inode->i_mode);
 360         if (!error)
 361                 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, clone);
 362
 363         posix_acl_release(clone);
 364         return error;
 365 }
 366
 367 static int
 368 xfs_xattr_acl_get(struct dentry *dentry, const char *name,
 369                 void *value, size_t size, int type)
 370 {
 371         struct posix_acl *acl;
 372         int error;
 373
 374         acl = xfs_get_acl(dentry->d_inode, type);
 375         if (IS_ERR(acl))
 376                 return PTR_ERR(acl);
 377         if (acl == NULL)
 378                 return -ENODATA;
 379
 380         error = posix_acl_to_xattr(acl, value, size);
 381         posix_acl_release(acl);
 382
 383         return error;
 384 }
 385
 386 static int
 387 xfs_xattr_acl_set(struct dentry *dentry, const char *name,
 388                 const void *value, size_t size, int flags, int type)
 389 {
 390         struct inode *inode = dentry->d_inode;
 391         struct posix_acl *acl = NULL;
 392         int error = 0;
 393
 394         if (flags & XATTR_CREATE)
 395                 return -EINVAL;
 396         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 397                 return value ? -EACCES : 0;
 398         if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
 399                 return -EPERM;
 400
 401         if (!value)
 402                 goto set_acl;
 403
 404         acl = posix_acl_from_xattr(value, size);
 405         if (!acl) {
 406                 /*
 407                  * acl_set_file(3) may request that we set default ACLs with
 408                  * zero length -- defend (gracefully) against that here.
 409                  */
 410                 goto out;
 411         }
 412         if (IS_ERR(acl)) {
 413                 error = PTR_ERR(acl);
 414                 goto out;
 415         }
 416
 417         error = posix_acl_valid(acl);
 418         if (error)
 419                 goto out_release;
 420
 421         error = -EINVAL;
 422         if (acl->a_count > XFS_ACL_MAX_ENTRIES)
 423                 goto out_release;
 424
 425         if (type == ACL_TYPE_ACCESS) {
 426                 mode_t mode = inode->i_mode;
 427                 error = posix_acl_equiv_mode(acl, &mode);
 428
 429                 if (error <= 0) {
 430                         posix_acl_release(acl);
 431                         acl = NULL;
 432
 433                         if (error < 0)
 434                                 return error;
 435                 }
 436
 437                 error = xfs_set_mode(inode, mode);
 438                 if (error)
 439                         goto out_release;
 440         }
 441
 442  set_acl:
 443         error = xfs_set_acl(inode, type, acl);
 444  out_release:
 445         posix_acl_release(acl);
 446  out:
 447         return error;
 448 }
 449
 450 const struct xattr_handler xfs_xattr_acl_access_handler = {
 451         .prefix = POSIX_ACL_XATTR_ACCESS,
 452         .flags  = ACL_TYPE_ACCESS,
 453         .get    = xfs_xattr_acl_get,
 454         .set    = xfs_xattr_acl_set,
 455 };
 456
 457 const struct xattr_handler xfs_xattr_acl_default_handler = {
 458         .prefix = POSIX_ACL_XATTR_DEFAULT,
 459         .flags  = ACL_TYPE_DEFAULT,
 460         .get    = xfs_xattr_acl_get,
 461         .set    = xfs_xattr_acl_set,
 462 };