fs/overlayfs/copy

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This source file includes following definitions.
ovl_ccup_set
ovl_ccup_get
ovl_copy_xattr
ovl_copy_up_data
ovl_set_size
ovl_set_timestamps
ovl_set_attr
ovl_encode_real_fh
ovl_set_origin
ovl_set_upper_fh
ovl_create_index
ovl_link_up
ovl_copy_up_inode
ovl_prep_cu_creds
ovl_revert_cu_creds
ovl_copy_up_workdir
ovl_copy_up_tmpfile
ovl_do_copy_up
ovl_need_meta_copy_up
ovl_copy_up_meta_inode_data
ovl_copy_up_one
ovl_copy_up_flags
ovl_open_need_copy_up
ovl_maybe_copy_up
ovl_copy_up_with_data
ovl_copy_up
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *
   4  * Copyright (C) 2011 Novell Inc.
   5  */
   6 
   7 #include <linux/module.h>
   8 #include <linux/fs.h>
   9 #include <linux/slab.h>
  10 #include <linux/file.h>
  11 #include <linux/splice.h>
  12 #include <linux/xattr.h>
  13 #include <linux/security.h>
  14 #include <linux/uaccess.h>
  15 #include <linux/sched/signal.h>
  16 #include <linux/cred.h>
  17 #include <linux/namei.h>
  18 #include <linux/fdtable.h>
  19 #include <linux/ratelimit.h>
  20 #include <linux/exportfs.h>
  21 #include "overlayfs.h"
  22 
  23 #define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
  24 
  25 static int ovl_ccup_set(const char *buf, const struct kernel_param *param)
  26 {
  27         pr_warn("overlayfs: \"check_copy_up\" module option is obsolete\n");
  28         return 0;
  29 }
  30 
  31 static int ovl_ccup_get(char *buf, const struct kernel_param *param)
  32 {
  33         return sprintf(buf, "N\n");
  34 }
  35 
  36 module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
  37 MODULE_PARM_DESC(check_copy_up, "Obsolete; does nothing");
  38 
  39 int ovl_copy_xattr(struct dentry *old, struct dentry *new)
  40 {
  41         ssize_t list_size, size, value_size = 0;
  42         char *buf, *name, *value = NULL;
  43         int error = 0;
  44         size_t slen;
  45 
  46         if (!(old->d_inode->i_opflags & IOP_XATTR) ||
  47             !(new->d_inode->i_opflags & IOP_XATTR))
  48                 return 0;
  49 
  50         list_size = vfs_listxattr(old, NULL, 0);
  51         if (list_size <= 0) {
  52                 if (list_size == -EOPNOTSUPP)
  53                         return 0;
  54                 return list_size;
  55         }
  56 
  57         buf = kzalloc(list_size, GFP_KERNEL);
  58         if (!buf)
  59                 return -ENOMEM;
  60 
  61         list_size = vfs_listxattr(old, buf, list_size);
  62         if (list_size <= 0) {
  63                 error = list_size;
  64                 goto out;
  65         }
  66 
  67         for (name = buf; list_size; name += slen) {
  68                 slen = strnlen(name, list_size) + 1;
  69 
  70                 /* underlying fs providing us with an broken xattr list? */
  71                 if (WARN_ON(slen > list_size)) {
  72                         error = -EIO;
  73                         break;
  74                 }
  75                 list_size -= slen;
  76 
  77                 if (ovl_is_private_xattr(name))
  78                         continue;
  79 retry:
  80                 size = vfs_getxattr(old, name, value, value_size);
  81                 if (size == -ERANGE)
  82                         size = vfs_getxattr(old, name, NULL, 0);
  83 
  84                 if (size < 0) {
  85                         error = size;
  86                         break;
  87                 }
  88 
  89                 if (size > value_size) {
  90                         void *new;
  91 
  92                         new = krealloc(value, size, GFP_KERNEL);
  93                         if (!new) {
  94                                 error = -ENOMEM;
  95                                 break;
  96                         }
  97                         value = new;
  98                         value_size = size;
  99                         goto retry;
 100                 }
 101 
 102                 error = security_inode_copy_up_xattr(name);
 103                 if (error < 0 && error != -EOPNOTSUPP)
 104                         break;
 105                 if (error == 1) {
 106                         error = 0;
 107                         continue; /* Discard */
 108                 }
 109                 error = vfs_setxattr(new, name, value, size, 0);
 110                 if (error)
 111                         break;
 112         }
 113         kfree(value);
 114 out:
 115         kfree(buf);
 116         return error;
 117 }
 118 
 119 static int ovl_copy_up_data(struct path *old, struct path *new, loff_t len)
 120 {
 121         struct file *old_file;
 122         struct file *new_file;
 123         loff_t old_pos = 0;
 124         loff_t new_pos = 0;
 125         loff_t cloned;
 126         int error = 0;
 127 
 128         if (len == 0)
 129                 return 0;
 130 
 131         old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
 132         if (IS_ERR(old_file))
 133                 return PTR_ERR(old_file);
 134 
 135         new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
 136         if (IS_ERR(new_file)) {
 137                 error = PTR_ERR(new_file);
 138                 goto out_fput;
 139         }
 140 
 141         /* Try to use clone_file_range to clone up within the same fs */
 142         cloned = do_clone_file_range(old_file, 0, new_file, 0, len, 0);
 143         if (cloned == len)
 144                 goto out;
 145         /* Couldn't clone, so now we try to copy the data */
 146 
 147         /* FIXME: copy up sparse files efficiently */
 148         while (len) {
 149                 size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
 150                 long bytes;
 151 
 152                 if (len < this_len)
 153                         this_len = len;
 154 
 155                 if (signal_pending_state(TASK_KILLABLE, current)) {
 156                         error = -EINTR;
 157                         break;
 158                 }
 159 
 160                 bytes = do_splice_direct(old_file, &old_pos,
 161                                          new_file, &new_pos,
 162                                          this_len, SPLICE_F_MOVE);
 163                 if (bytes <= 0) {
 164                         error = bytes;
 165                         break;
 166                 }
 167                 WARN_ON(old_pos != new_pos);
 168 
 169                 len -= bytes;
 170         }
 171 out:
 172         if (!error)
 173                 error = vfs_fsync(new_file, 0);
 174         fput(new_file);
 175 out_fput:
 176         fput(old_file);
 177         return error;
 178 }
 179 
 180 static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
 181 {
 182         struct iattr attr = {
 183                 .ia_valid = ATTR_SIZE,
 184                 .ia_size = stat->size,
 185         };
 186 
 187         return notify_change(upperdentry, &attr, NULL);
 188 }
 189 
 190 static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
 191 {
 192         struct iattr attr = {
 193                 .ia_valid =
 194                      ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
 195                 .ia_atime = stat->atime,
 196                 .ia_mtime = stat->mtime,
 197         };
 198 
 199         return notify_change(upperdentry, &attr, NULL);
 200 }
 201 
 202 int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
 203 {
 204         int err = 0;
 205 
 206         if (!S_ISLNK(stat->mode)) {
 207                 struct iattr attr = {
 208                         .ia_valid = ATTR_MODE,
 209                         .ia_mode = stat->mode,
 210                 };
 211                 err = notify_change(upperdentry, &attr, NULL);
 212         }
 213         if (!err) {
 214                 struct iattr attr = {
 215                         .ia_valid = ATTR_UID | ATTR_GID,
 216                         .ia_uid = stat->uid,
 217                         .ia_gid = stat->gid,
 218                 };
 219                 err = notify_change(upperdentry, &attr, NULL);
 220         }
 221         if (!err)
 222                 ovl_set_timestamps(upperdentry, stat);
 223 
 224         return err;
 225 }
 226 
 227 struct ovl_fh *ovl_encode_real_fh(struct dentry *real, bool is_upper)
 228 {
 229         struct ovl_fh *fh;
 230         int fh_type, fh_len, dwords;
 231         void *buf;
 232         int buflen = MAX_HANDLE_SZ;
 233         uuid_t *uuid = &real->d_sb->s_uuid;
 234 
 235         buf = kmalloc(buflen, GFP_KERNEL);
 236         if (!buf)
 237                 return ERR_PTR(-ENOMEM);
 238 
 239         /*
 240          * We encode a non-connectable file handle for non-dir, because we
 241          * only need to find the lower inode number and we don't want to pay
 242          * the price or reconnecting the dentry.
 243          */
 244         dwords = buflen >> 2;
 245         fh_type = exportfs_encode_fh(real, buf, &dwords, 0);
 246         buflen = (dwords << 2);
 247 
 248         fh = ERR_PTR(-EIO);
 249         if (WARN_ON(fh_type < 0) ||
 250             WARN_ON(buflen > MAX_HANDLE_SZ) ||
 251             WARN_ON(fh_type == FILEID_INVALID))
 252                 goto out;
 253 
 254         BUILD_BUG_ON(MAX_HANDLE_SZ + offsetof(struct ovl_fh, fid) > 255);
 255         fh_len = offsetof(struct ovl_fh, fid) + buflen;
 256         fh = kmalloc(fh_len, GFP_KERNEL);
 257         if (!fh) {
 258                 fh = ERR_PTR(-ENOMEM);
 259                 goto out;
 260         }
 261 
 262         fh->version = OVL_FH_VERSION;
 263         fh->magic = OVL_FH_MAGIC;
 264         fh->type = fh_type;
 265         fh->flags = OVL_FH_FLAG_CPU_ENDIAN;
 266         /*
 267          * When we will want to decode an overlay dentry from this handle
 268          * and all layers are on the same fs, if we get a disconncted real
 269          * dentry when we decode fid, the only way to tell if we should assign
 270          * it to upperdentry or to lowerstack is by checking this flag.
 271          */
 272         if (is_upper)
 273                 fh->flags |= OVL_FH_FLAG_PATH_UPPER;
 274         fh->len = fh_len;
 275         fh->uuid = *uuid;
 276         memcpy(fh->fid, buf, buflen);
 277 
 278 out:
 279         kfree(buf);
 280         return fh;
 281 }
 282 
 283 int ovl_set_origin(struct dentry *dentry, struct dentry *lower,
 284                    struct dentry *upper)
 285 {
 286         const struct ovl_fh *fh = NULL;
 287         int err;
 288 
 289         /*
 290          * When lower layer doesn't support export operations store a 'null' fh,
 291          * so we can use the overlay.origin xattr to distignuish between a copy
 292          * up and a pure upper inode.
 293          */
 294         if (ovl_can_decode_fh(lower->d_sb)) {
 295                 fh = ovl_encode_real_fh(lower, false);
 296                 if (IS_ERR(fh))
 297                         return PTR_ERR(fh);
 298         }
 299 
 300         /*
 301          * Do not fail when upper doesn't support xattrs.
 302          */
 303         err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh,
 304                                  fh ? fh->len : 0, 0);
 305         kfree(fh);
 306 
 307         return err;
 308 }
 309 
 310 /* Store file handle of @upper dir in @index dir entry */
 311 static int ovl_set_upper_fh(struct dentry *upper, struct dentry *index)
 312 {
 313         const struct ovl_fh *fh;
 314         int err;
 315 
 316         fh = ovl_encode_real_fh(upper, true);
 317         if (IS_ERR(fh))
 318                 return PTR_ERR(fh);
 319 
 320         err = ovl_do_setxattr(index, OVL_XATTR_UPPER, fh, fh->len, 0);
 321 
 322         kfree(fh);
 323         return err;
 324 }
 325 
 326 /*
 327  * Create and install index entry.
 328  *
 329  * Caller must hold i_mutex on indexdir.
 330  */
 331 static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
 332                             struct dentry *upper)
 333 {
 334         struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
 335         struct inode *dir = d_inode(indexdir);
 336         struct dentry *index = NULL;
 337         struct dentry *temp = NULL;
 338         struct qstr name = { };
 339         int err;
 340 
 341         /*
 342          * For now this is only used for creating index entry for directories,
 343          * because non-dir are copied up directly to index and then hardlinked
 344          * to upper dir.
 345          *
 346          * TODO: implement create index for non-dir, so we can call it when
 347          * encoding file handle for non-dir in case index does not exist.
 348          */
 349         if (WARN_ON(!d_is_dir(dentry)))
 350                 return -EIO;
 351 
 352         /* Directory not expected to be indexed before copy up */
 353         if (WARN_ON(ovl_test_flag(OVL_INDEX, d_inode(dentry))))
 354                 return -EIO;
 355 
 356         err = ovl_get_index_name(origin, &name);
 357         if (err)
 358                 return err;
 359 
 360         temp = ovl_create_temp(indexdir, OVL_CATTR(S_IFDIR | 0));
 361         err = PTR_ERR(temp);
 362         if (IS_ERR(temp))
 363                 goto free_name;
 364 
 365         err = ovl_set_upper_fh(upper, temp);
 366         if (err)
 367                 goto out;
 368 
 369         index = lookup_one_len(name.name, indexdir, name.len);
 370         if (IS_ERR(index)) {
 371                 err = PTR_ERR(index);
 372         } else {
 373                 err = ovl_do_rename(dir, temp, dir, index, 0);
 374                 dput(index);
 375         }
 376 out:
 377         if (err)
 378                 ovl_cleanup(dir, temp);
 379         dput(temp);
 380 free_name:
 381         kfree(name.name);
 382         return err;
 383 }
 384 
 385 struct ovl_copy_up_ctx {
 386         struct dentry *parent;
 387         struct dentry *dentry;
 388         struct path lowerpath;
 389         struct kstat stat;
 390         struct kstat pstat;
 391         const char *link;
 392         struct dentry *destdir;
 393         struct qstr destname;
 394         struct dentry *workdir;
 395         bool origin;
 396         bool indexed;
 397         bool metacopy;
 398 };
 399 
 400 static int ovl_link_up(struct ovl_copy_up_ctx *c)
 401 {
 402         int err;
 403         struct dentry *upper;
 404         struct dentry *upperdir = ovl_dentry_upper(c->parent);
 405         struct inode *udir = d_inode(upperdir);
 406 
 407         /* Mark parent "impure" because it may now contain non-pure upper */
 408         err = ovl_set_impure(c->parent, upperdir);
 409         if (err)
 410                 return err;
 411 
 412         err = ovl_set_nlink_lower(c->dentry);
 413         if (err)
 414                 return err;
 415 
 416         inode_lock_nested(udir, I_MUTEX_PARENT);
 417         upper = lookup_one_len(c->dentry->d_name.name, upperdir,
 418                                c->dentry->d_name.len);
 419         err = PTR_ERR(upper);
 420         if (!IS_ERR(upper)) {
 421                 err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper);
 422                 dput(upper);
 423 
 424                 if (!err) {
 425                         /* Restore timestamps on parent (best effort) */
 426                         ovl_set_timestamps(upperdir, &c->pstat);
 427                         ovl_dentry_set_upper_alias(c->dentry);
 428                 }
 429         }
 430         inode_unlock(udir);
 431         if (err)
 432                 return err;
 433 
 434         err = ovl_set_nlink_upper(c->dentry);
 435 
 436         return err;
 437 }
 438 
 439 static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
 440 {
 441         int err;
 442 
 443         /*
 444          * Copy up data first and then xattrs. Writing data after
 445          * xattrs will remove security.capability xattr automatically.
 446          */
 447         if (S_ISREG(c->stat.mode) && !c->metacopy) {
 448                 struct path upperpath, datapath;
 449 
 450                 ovl_path_upper(c->dentry, &upperpath);
 451                 if (WARN_ON(upperpath.dentry != NULL))
 452                         return -EIO;
 453                 upperpath.dentry = temp;
 454 
 455                 ovl_path_lowerdata(c->dentry, &datapath);
 456                 err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size);
 457                 if (err)
 458                         return err;
 459         }
 460 
 461         err = ovl_copy_xattr(c->lowerpath.dentry, temp);
 462         if (err)
 463                 return err;
 464 
 465         /*
 466          * Store identifier of lower inode in upper inode xattr to
 467          * allow lookup of the copy up origin inode.
 468          *
 469          * Don't set origin when we are breaking the association with a lower
 470          * hard link.
 471          */
 472         if (c->origin) {
 473                 err = ovl_set_origin(c->dentry, c->lowerpath.dentry, temp);
 474                 if (err)
 475                         return err;
 476         }
 477 
 478         if (c->metacopy) {
 479                 err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY,
 480                                          NULL, 0, -EOPNOTSUPP);
 481                 if (err)
 482                         return err;
 483         }
 484 
 485         inode_lock(temp->d_inode);
 486         if (c->metacopy)
 487                 err = ovl_set_size(temp, &c->stat);
 488         if (!err)
 489                 err = ovl_set_attr(temp, &c->stat);
 490         inode_unlock(temp->d_inode);
 491 
 492         return err;
 493 }
 494 
 495 struct ovl_cu_creds {
 496         const struct cred *old;
 497         struct cred *new;
 498 };
 499 
 500 static int ovl_prep_cu_creds(struct dentry *dentry, struct ovl_cu_creds *cc)
 501 {
 502         int err;
 503 
 504         cc->old = cc->new = NULL;
 505         err = security_inode_copy_up(dentry, &cc->new);
 506         if (err < 0)
 507                 return err;
 508 
 509         if (cc->new)
 510                 cc->old = override_creds(cc->new);
 511 
 512         return 0;
 513 }
 514 
 515 static void ovl_revert_cu_creds(struct ovl_cu_creds *cc)
 516 {
 517         if (cc->new) {
 518                 revert_creds(cc->old);
 519                 put_cred(cc->new);
 520         }
 521 }
 522 
 523 /*
 524  * Copyup using workdir to prepare temp file.  Used when copying up directories,
 525  * special files or when upper fs doesn't support O_TMPFILE.
 526  */
 527 static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
 528 {
 529         struct inode *inode;
 530         struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir);
 531         struct dentry *temp, *upper;
 532         struct ovl_cu_creds cc;
 533         int err;
 534         struct ovl_cattr cattr = {
 535                 /* Can't properly set mode on creation because of the umask */
 536                 .mode = c->stat.mode & S_IFMT,
 537                 .rdev = c->stat.rdev,
 538                 .link = c->link
 539         };
 540 
 541         err = ovl_lock_rename_workdir(c->workdir, c->destdir);
 542         if (err)
 543                 return err;
 544 
 545         err = ovl_prep_cu_creds(c->dentry, &cc);
 546         if (err)
 547                 goto unlock;
 548 
 549         temp = ovl_create_temp(c->workdir, &cattr);
 550         ovl_revert_cu_creds(&cc);
 551 
 552         err = PTR_ERR(temp);
 553         if (IS_ERR(temp))
 554                 goto unlock;
 555 
 556         err = ovl_copy_up_inode(c, temp);
 557         if (err)
 558                 goto cleanup;
 559 
 560         if (S_ISDIR(c->stat.mode) && c->indexed) {
 561                 err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
 562                 if (err)
 563                         goto cleanup;
 564         }
 565 
 566         upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
 567         err = PTR_ERR(upper);
 568         if (IS_ERR(upper))
 569                 goto cleanup;
 570 
 571         err = ovl_do_rename(wdir, temp, udir, upper, 0);
 572         dput(upper);
 573         if (err)
 574                 goto cleanup;
 575 
 576         if (!c->metacopy)
 577                 ovl_set_upperdata(d_inode(c->dentry));
 578         inode = d_inode(c->dentry);
 579         ovl_inode_update(inode, temp);
 580         if (S_ISDIR(inode->i_mode))
 581                 ovl_set_flag(OVL_WHITEOUTS, inode);
 582 unlock:
 583         unlock_rename(c->workdir, c->destdir);
 584 
 585         return err;
 586 
 587 cleanup:
 588         ovl_cleanup(wdir, temp);
 589         dput(temp);
 590         goto unlock;
 591 }
 592 
 593 /* Copyup using O_TMPFILE which does not require cross dir locking */
 594 static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
 595 {
 596         struct inode *udir = d_inode(c->destdir);
 597         struct dentry *temp, *upper;
 598         struct ovl_cu_creds cc;
 599         int err;
 600 
 601         err = ovl_prep_cu_creds(c->dentry, &cc);
 602         if (err)
 603                 return err;
 604 
 605         temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
 606         ovl_revert_cu_creds(&cc);
 607 
 608         if (IS_ERR(temp))
 609                 return PTR_ERR(temp);
 610 
 611         err = ovl_copy_up_inode(c, temp);
 612         if (err)
 613                 goto out_dput;
 614 
 615         inode_lock_nested(udir, I_MUTEX_PARENT);
 616 
 617         upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
 618         err = PTR_ERR(upper);
 619         if (!IS_ERR(upper)) {
 620                 err = ovl_do_link(temp, udir, upper);
 621                 dput(upper);
 622         }
 623         inode_unlock(udir);
 624 
 625         if (err)
 626                 goto out_dput;
 627 
 628         if (!c->metacopy)
 629                 ovl_set_upperdata(d_inode(c->dentry));
 630         ovl_inode_update(d_inode(c->dentry), temp);
 631 
 632         return 0;
 633 
 634 out_dput:
 635         dput(temp);
 636         return err;
 637 }
 638 
 639 /*
 640  * Copy up a single dentry
 641  *
 642  * All renames start with copy up of source if necessary.  The actual
 643  * rename will only proceed once the copy up was successful.  Copy up uses
 644  * upper parent i_mutex for exclusion.  Since rename can change d_parent it
 645  * is possible that the copy up will lock the old parent.  At that point
 646  * the file will have already been copied up anyway.
 647  */
 648 static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
 649 {
 650         int err;
 651         struct ovl_fs *ofs = c->dentry->d_sb->s_fs_info;
 652         bool to_index = false;
 653 
 654         /*
 655          * Indexed non-dir is copied up directly to the index entry and then
 656          * hardlinked to upper dir. Indexed dir is copied up to indexdir,
 657          * then index entry is created and then copied up dir installed.
 658          * Copying dir up to indexdir instead of workdir simplifies locking.
 659          */
 660         if (ovl_need_index(c->dentry)) {
 661                 c->indexed = true;
 662                 if (S_ISDIR(c->stat.mode))
 663                         c->workdir = ovl_indexdir(c->dentry->d_sb);
 664                 else
 665                         to_index = true;
 666         }
 667 
 668         if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index)
 669                 c->origin = true;
 670 
 671         if (to_index) {
 672                 c->destdir = ovl_indexdir(c->dentry->d_sb);
 673                 err = ovl_get_index_name(c->lowerpath.dentry, &c->destname);
 674                 if (err)
 675                         return err;
 676         } else if (WARN_ON(!c->parent)) {
 677                 /* Disconnected dentry must be copied up to index dir */
 678                 return -EIO;
 679         } else {
 680                 /*
 681                  * Mark parent "impure" because it may now contain non-pure
 682                  * upper
 683                  */
 684                 err = ovl_set_impure(c->parent, c->destdir);
 685                 if (err)
 686                         return err;
 687         }
 688 
 689         /* Should we copyup with O_TMPFILE or with workdir? */
 690         if (S_ISREG(c->stat.mode) && ofs->tmpfile)
 691                 err = ovl_copy_up_tmpfile(c);
 692         else
 693                 err = ovl_copy_up_workdir(c);
 694         if (err)
 695                 goto out;
 696 
 697         if (c->indexed)
 698                 ovl_set_flag(OVL_INDEX, d_inode(c->dentry));
 699 
 700         if (to_index) {
 701                 /* Initialize nlink for copy up of disconnected dentry */
 702                 err = ovl_set_nlink_upper(c->dentry);
 703         } else {
 704                 struct inode *udir = d_inode(c->destdir);
 705 
 706                 /* Restore timestamps on parent (best effort) */
 707                 inode_lock(udir);
 708                 ovl_set_timestamps(c->destdir, &c->pstat);
 709                 inode_unlock(udir);
 710 
 711                 ovl_dentry_set_upper_alias(c->dentry);
 712         }
 713 
 714 out:
 715         if (to_index)
 716                 kfree(c->destname.name);
 717         return err;
 718 }
 719 
 720 static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
 721                                   int flags)
 722 {
 723         struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
 724 
 725         if (!ofs->config.metacopy)
 726                 return false;
 727 
 728         if (!S_ISREG(mode))
 729                 return false;
 730 
 731         if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
 732                 return false;
 733 
 734         return true;
 735 }
 736 
 737 /* Copy up data of an inode which was copied up metadata only in the past. */
 738 static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
 739 {
 740         struct path upperpath, datapath;
 741         int err;
 742         char *capability = NULL;
 743         ssize_t uninitialized_var(cap_size);
 744 
 745         ovl_path_upper(c->dentry, &upperpath);
 746         if (WARN_ON(upperpath.dentry == NULL))
 747                 return -EIO;
 748 
 749         ovl_path_lowerdata(c->dentry, &datapath);
 750         if (WARN_ON(datapath.dentry == NULL))
 751                 return -EIO;
 752 
 753         if (c->stat.size) {
 754                 err = cap_size = ovl_getxattr(upperpath.dentry, XATTR_NAME_CAPS,
 755                                               &capability, 0);
 756                 if (err < 0 && err != -ENODATA)
 757                         goto out;
 758         }
 759 
 760         err = ovl_copy_up_data(&datapath, &upperpath, c->stat.size);
 761         if (err)
 762                 goto out_free;
 763 
 764         /*
 765          * Writing to upper file will clear security.capability xattr. We
 766          * don't want that to happen for normal copy-up operation.
 767          */
 768         if (capability) {
 769                 err = ovl_do_setxattr(upperpath.dentry, XATTR_NAME_CAPS,
 770                                       capability, cap_size, 0);
 771                 if (err)
 772                         goto out_free;
 773         }
 774 
 775 
 776         err = vfs_removexattr(upperpath.dentry, OVL_XATTR_METACOPY);
 777         if (err)
 778                 goto out_free;
 779 
 780         ovl_set_upperdata(d_inode(c->dentry));
 781 out_free:
 782         kfree(capability);
 783 out:
 784         return err;
 785 }
 786 
 787 static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
 788                            int flags)
 789 {
 790         int err;
 791         DEFINE_DELAYED_CALL(done);
 792         struct path parentpath;
 793         struct ovl_copy_up_ctx ctx = {
 794                 .parent = parent,
 795                 .dentry = dentry,
 796                 .workdir = ovl_workdir(dentry),
 797         };
 798 
 799         if (WARN_ON(!ctx.workdir))
 800                 return -EROFS;
 801 
 802         ovl_path_lower(dentry, &ctx.lowerpath);
 803         err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
 804                           STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
 805         if (err)
 806                 return err;
 807 
 808         ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags);
 809 
 810         if (parent) {
 811                 ovl_path_upper(parent, &parentpath);
 812                 ctx.destdir = parentpath.dentry;
 813                 ctx.destname = dentry->d_name;
 814 
 815                 err = vfs_getattr(&parentpath, &ctx.pstat,
 816                                   STATX_ATIME | STATX_MTIME,
 817                                   AT_STATX_SYNC_AS_STAT);
 818                 if (err)
 819                         return err;
 820         }
 821 
 822         /* maybe truncate regular file. this has no effect on dirs */
 823         if (flags & O_TRUNC)
 824                 ctx.stat.size = 0;
 825 
 826         if (S_ISLNK(ctx.stat.mode)) {
 827                 ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
 828                 if (IS_ERR(ctx.link))
 829                         return PTR_ERR(ctx.link);
 830         }
 831 
 832         err = ovl_copy_up_start(dentry, flags);
 833         /* err < 0: interrupted, err > 0: raced with another copy-up */
 834         if (unlikely(err)) {
 835                 if (err > 0)
 836                         err = 0;
 837         } else {
 838                 if (!ovl_dentry_upper(dentry))
 839                         err = ovl_do_copy_up(&ctx);
 840                 if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
 841                         err = ovl_link_up(&ctx);
 842                 if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags))
 843                         err = ovl_copy_up_meta_inode_data(&ctx);
 844                 ovl_copy_up_end(dentry);
 845         }
 846         do_delayed_call(&done);
 847 
 848         return err;
 849 }
 850 
 851 int ovl_copy_up_flags(struct dentry *dentry, int flags)
 852 {
 853         int err = 0;
 854         const struct cred *old_cred = ovl_override_creds(dentry->d_sb);
 855         bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);
 856 
 857         /*
 858          * With NFS export, copy up can get called for a disconnected non-dir.
 859          * In this case, we will copy up lower inode to index dir without
 860          * linking it to upper dir.
 861          */
 862         if (WARN_ON(disconnected && d_is_dir(dentry)))
 863                 return -EIO;
 864 
 865         while (!err) {
 866                 struct dentry *next;
 867                 struct dentry *parent = NULL;
 868 
 869                 if (ovl_already_copied_up(dentry, flags))
 870                         break;
 871 
 872                 next = dget(dentry);
 873                 /* find the topmost dentry not yet copied up */
 874                 for (; !disconnected;) {
 875                         parent = dget_parent(next);
 876 
 877                         if (ovl_dentry_upper(parent))
 878                                 break;
 879 
 880                         dput(next);
 881                         next = parent;
 882                 }
 883 
 884                 err = ovl_copy_up_one(parent, next, flags);
 885 
 886                 dput(parent);
 887                 dput(next);
 888         }
 889         revert_creds(old_cred);
 890 
 891         return err;
 892 }
 893 
 894 static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
 895 {
 896         /* Copy up of disconnected dentry does not set upper alias */
 897         if (ovl_already_copied_up(dentry, flags))
 898                 return false;
 899 
 900         if (special_file(d_inode(dentry)->i_mode))
 901                 return false;
 902 
 903         if (!ovl_open_flags_need_copy_up(flags))
 904                 return false;
 905 
 906         return true;
 907 }
 908 
 909 int ovl_maybe_copy_up(struct dentry *dentry, int flags)
 910 {
 911         int err = 0;
 912 
 913         if (ovl_open_need_copy_up(dentry, flags)) {
 914                 err = ovl_want_write(dentry);
 915                 if (!err) {
 916                         err = ovl_copy_up_flags(dentry, flags);
 917                         ovl_drop_write(dentry);
 918                 }
 919         }
 920 
 921         return err;
 922 }
 923 
 924 int ovl_copy_up_with_data(struct dentry *dentry)
 925 {
 926         return ovl_copy_up_flags(dentry, O_WRONLY);
 927 }
 928 
 929 int ovl_copy_up(struct dentry *dentry)
 930 {
 931         return ovl_copy_up_flags(dentry, 0);
 932 }
/* [<][>][^][v][top][bottom][index][help] */
root/fs/overlayfs/copy_up.c

DEFINITIONS
