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;
 128         struct xfs_acl *xfs_acl;
 129         unsigned char *ea_name;
 130         int error;
 131         int len;
 132
 133         acl = get_cached_acl(inode, type);
 134         if (acl != ACL_NOT_CACHED)
 135                 return acl;
 136
 137         trace_xfs_get_acl(ip);
 138
 139         switch (type) {
 140         case ACL_TYPE_ACCESS:
 141                 ea_name = SGI_ACL_FILE;
 142                 break;
 143         case ACL_TYPE_DEFAULT:
 144                 ea_name = SGI_ACL_DEFAULT;
 145                 break;
 146         default:
 147                 BUG();
 148         }
 149
 150         /*
 151          * If we have a cached ACLs value just return it, not need to
 152          * go out to the disk.
 153          */
 154         len = XFS_ACL_MAX_SIZE(ip->i_mount);
 155         xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 156         if (!xfs_acl)
 157                 return ERR_PTR(-ENOMEM);
 158
 159         error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
 160                                                         &len, ATTR_ROOT);
 161         if (error) {
 162                 /*
 163                  * If the attribute doesn't exist make sure we have a negative
 164                  * cache entry, for any other error assume it is transient and
 165                  * leave the cache entry as ACL_NOT_CACHED.
 166                  */
 167                 if (error == -ENOATTR) {
 168                         acl = NULL;
 169                         goto out_update_cache;
 170                 }
 171                 goto out;
 172         }
 173
 174         acl = xfs_acl_from_disk(xfs_acl, XFS_ACL_MAX_ENTRIES(ip->i_mount));
 175         if (IS_ERR(acl))
 176                 goto out;
 177
 178 out_update_cache:
 179         set_cached_acl(inode, type, acl);
 180 out:
 181         kmem_free(xfs_acl);
 182         return acl;
 183 }
 184
 185 STATIC int
 186 xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
 187 {
 188         struct xfs_inode *ip = XFS_I(inode);
 189         unsigned char *ea_name;
 190         int error;
 191
 192         if (S_ISLNK(inode->i_mode))
 193                 return -EOPNOTSUPP;
 194
 195         switch (type) {
 196         case ACL_TYPE_ACCESS:
 197                 ea_name = SGI_ACL_FILE;
 198                 break;
 199         case ACL_TYPE_DEFAULT:
 200                 if (!S_ISDIR(inode->i_mode))
 201                         return acl ? -EACCES : 0;
 202                 ea_name = SGI_ACL_DEFAULT;
 203                 break;
 204         default:
 205                 return -EINVAL;
 206         }
 207
 208         if (acl) {
 209                 struct xfs_acl *xfs_acl;
 210                 int len = XFS_ACL_MAX_SIZE(ip->i_mount);
 211
 212                 xfs_acl = kmem_zalloc_large(len, KM_SLEEP);
 213                 if (!xfs_acl)
 214                         return -ENOMEM;
 215
 216                 xfs_acl_to_disk(xfs_acl, acl);
 217
 218                 /* subtract away the unused acl entries */
 219                 len -= sizeof(struct xfs_acl_entry) *
 220                          (XFS_ACL_MAX_ENTRIES(ip->i_mount) - acl->a_count);
 221
 222                 error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,
 223                                 len, ATTR_ROOT);
 224
 225                 kmem_free(xfs_acl);
 226         } else {
 227                 /*
 228                  * A NULL ACL argument means we want to remove the ACL.
 229                  */
 230                 error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
 231
 232                 /*
 233                  * If the attribute didn't exist to start with that's fine.
 234                  */
 235                 if (error == -ENOATTR)
 236                         error = 0;
 237         }
 238
 239         if (!error)
 240                 set_cached_acl(inode, type, acl);
 241         return error;
 242 }
 243
 244 static int
 245 xfs_set_mode(struct inode *inode, umode_t mode)
 246 {
 247         int error = 0;
 248
 249         if (mode != inode->i_mode) {
 250                 struct iattr iattr;
 251
 252                 iattr.ia_valid = ATTR_MODE | ATTR_CTIME;
 253                 iattr.ia_mode = mode;
 254                 iattr.ia_ctime = current_fs_time(inode->i_sb);
 255
 256                 error = -xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);
 257         }
 258
 259         return error;
 260 }
 261
 262 static int
 263 xfs_acl_exists(struct inode *inode, unsigned char *name)
 264 {
 265         int len = XFS_ACL_MAX_SIZE(XFS_M(inode->i_sb));
 266
 267         return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
 268                             ATTR_ROOT|ATTR_KERNOVAL) == 0);
 269 }
 270
 271 int
 272 posix_acl_access_exists(struct inode *inode)
 273 {
 274         return xfs_acl_exists(inode, SGI_ACL_FILE);
 275 }
 276
 277 int
 278 posix_acl_default_exists(struct inode *inode)
 279 {
 280         if (!S_ISDIR(inode->i_mode))
 281                 return 0;
 282         return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
 283 }
 284
 285 /*
 286  * No need for i_mutex because the inode is not yet exposed to the VFS.
 287  */
 288 int
 289 xfs_inherit_acl(struct inode *inode, struct posix_acl *acl)
 290 {
 291         umode_t mode = inode->i_mode;
 292         int error = 0, inherit = 0;
 293
 294         if (S_ISDIR(inode->i_mode)) {
 295                 error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, acl);
 296                 if (error)
 297                         goto out;
 298         }
 299
 300         error = posix_acl_create(&acl, GFP_KERNEL, &mode);
 301         if (error < 0)
 302                 return error;
 303
 304         /*
 305          * If posix_acl_create returns a positive value we need to
 306          * inherit a permission that can't be represented using the Unix
 307          * mode bits and we actually need to set an ACL.
 308          */
 309         if (error > 0)
 310                 inherit = 1;
 311
 312         error = xfs_set_mode(inode, mode);
 313         if (error)
 314                 goto out;
 315
 316         if (inherit)
 317                 error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);
 318
 319 out:
 320         posix_acl_release(acl);
 321         return error;
 322 }
 323
 324 int
 325 xfs_acl_chmod(struct inode *inode)
 326 {
 327         struct posix_acl *acl;
 328         int error;
 329
 330         if (S_ISLNK(inode->i_mode))
 331                 return -EOPNOTSUPP;
 332
 333         acl = xfs_get_acl(inode, ACL_TYPE_ACCESS);
 334         if (IS_ERR(acl) || !acl)
 335                 return PTR_ERR(acl);
 336
 337         error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
 338         if (error)
 339                 return error;
 340
 341         error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);
 342         posix_acl_release(acl);
 343         return error;
 344 }
 345
 346 static int
 347 xfs_xattr_acl_get(struct dentry *dentry, const char *name,
 348                 void *value, size_t size, int type)
 349 {
 350         struct posix_acl *acl;
 351         int error;
 352
 353         acl = xfs_get_acl(dentry->d_inode, type);
 354         if (IS_ERR(acl))
 355                 return PTR_ERR(acl);
 356         if (acl == NULL)
 357                 return -ENODATA;
 358
 359         error = posix_acl_to_xattr(&init_user_ns, acl, value, size);
 360         posix_acl_release(acl);
 361
 362         return error;
 363 }
 364
 365 static int
 366 xfs_xattr_acl_set(struct dentry *dentry, const char *name,
 367                 const void *value, size_t size, int flags, int type)
 368 {
 369         struct inode *inode = dentry->d_inode;
 370         struct posix_acl *acl = NULL;
 371         int error = 0;
 372
 373         if (flags & XATTR_CREATE)
 374                 return -EINVAL;
 375         if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 376                 return value ? -EACCES : 0;
 377         if (!inode_owner_or_capable(inode))
 378                 return -EPERM;
 379
 380         if (!value)
 381                 goto set_acl;
 382
 383         acl = posix_acl_from_xattr(&init_user_ns, value, size);
 384         if (!acl) {
 385                 /*
 386                  * acl_set_file(3) may request that we set default ACLs with
 387                  * zero length -- defend (gracefully) against that here.
 388                  */
 389                 goto out;
 390         }
 391         if (IS_ERR(acl)) {
 392                 error = PTR_ERR(acl);
 393                 goto out;
 394         }
 395
 396         error = posix_acl_valid(acl);
 397         if (error)
 398                 goto out_release;
 399
 400         error = -EINVAL;
 401         if (acl->a_count > XFS_ACL_MAX_ENTRIES(XFS_M(inode->i_sb)))
 402                 goto out_release;
 403
 404         if (type == ACL_TYPE_ACCESS) {
 405                 umode_t mode = inode->i_mode;
 406                 error = posix_acl_equiv_mode(acl, &mode);
 407
 408                 if (error <= 0) {
 409                         posix_acl_release(acl);
 410                         acl = NULL;
 411
 412                         if (error < 0)
 413                                 return error;
 414                 }
 415
 416                 error = xfs_set_mode(inode, mode);
 417                 if (error)
 418                         goto out_release;
 419         }
 420
 421  set_acl:
 422         error = xfs_set_acl(inode, type, acl);
 423  out_release:
 424         posix_acl_release(acl);
 425  out:
 426         return error;
 427 }
 428
 429 const struct xattr_handler xfs_xattr_acl_access_handler = {
 430         .prefix = POSIX_ACL_XATTR_ACCESS,
 431         .flags  = ACL_TYPE_ACCESS,
 432         .get    = xfs_xattr_acl_get,
 433         .set    = xfs_xattr_acl_set,
 434 };
 435
 436 const struct xattr_handler xfs_xattr_acl_default_handler = {
 437         .prefix = POSIX_ACL_XATTR_DEFAULT,
 438         .flags  = ACL_TYPE_DEFAULT,
 439         .get    = xfs_xattr_acl_get,
 440         .set    = xfs_xattr_acl_set,
 441 };