fs/vboxsf/dir.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * VirtualBox Guest Shared Folders support: Directory inode and file operations
   4  *
   5  * Copyright (C) 2006-2018 Oracle Corporation
   6  */
   7
   8 #include <linux/namei.h>
   9 #include <linux/vbox_utils.h>
  10 #include "vfsmod.h"
  11
  12 static int vboxsf_dir_open(struct inode *inode, struct file *file)
  13 {
  14         struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
  15         struct shfl_createparms params = {};
  16         struct vboxsf_dir_info *sf_d;
  17         int err;
  18
  19         sf_d = vboxsf_dir_info_alloc();
  20         if (!sf_d)
  21                 return -ENOMEM;
  22
  23         params.handle = SHFL_HANDLE_NIL;
  24         params.create_flags = SHFL_CF_DIRECTORY | SHFL_CF_ACT_OPEN_IF_EXISTS |
  25                               SHFL_CF_ACT_FAIL_IF_NEW | SHFL_CF_ACCESS_READ;
  26
  27         err = vboxsf_create_at_dentry(file_dentry(file), &params);
  28         if (err)
  29                 goto err_free_dir_info;
  30
  31         if (params.result != SHFL_FILE_EXISTS) {
  32                 err = -ENOENT;
  33                 goto err_close;
  34         }
  35
  36         err = vboxsf_dir_read_all(sbi, sf_d, params.handle);
  37         if (err)
  38                 goto err_close;
  39
  40         vboxsf_close(sbi->root, params.handle);
  41         file->private_data = sf_d;
  42         return 0;
  43
  44 err_close:
  45         vboxsf_close(sbi->root, params.handle);
  46 err_free_dir_info:
  47         vboxsf_dir_info_free(sf_d);
  48         return err;
  49 }
  50
  51 static int vboxsf_dir_release(struct inode *inode, struct file *file)
  52 {
  53         if (file->private_data)
  54                 vboxsf_dir_info_free(file->private_data);
  55
  56         return 0;
  57 }
  58
  59 static unsigned int vboxsf_get_d_type(u32 mode)
  60 {
  61         unsigned int d_type;
  62
  63         switch (mode & SHFL_TYPE_MASK) {
  64         case SHFL_TYPE_FIFO:
  65                 d_type = DT_FIFO;
  66                 break;
  67         case SHFL_TYPE_DEV_CHAR:
  68                 d_type = DT_CHR;
  69                 break;
  70         case SHFL_TYPE_DIRECTORY:
  71                 d_type = DT_DIR;
  72                 break;
  73         case SHFL_TYPE_DEV_BLOCK:
  74                 d_type = DT_BLK;
  75                 break;
  76         case SHFL_TYPE_FILE:
  77                 d_type = DT_REG;
  78                 break;
  79         case SHFL_TYPE_SYMLINK:
  80                 d_type = DT_LNK;
  81                 break;
  82         case SHFL_TYPE_SOCKET:
  83                 d_type = DT_SOCK;
  84                 break;
  85         case SHFL_TYPE_WHITEOUT:
  86                 d_type = DT_WHT;
  87                 break;
  88         default:
  89                 d_type = DT_UNKNOWN;
  90                 break;
  91         }
  92         return d_type;
  93 }
  94
  95 static bool vboxsf_dir_emit(struct file *dir, struct dir_context *ctx)
  96 {
  97         struct vboxsf_sbi *sbi = VBOXSF_SBI(file_inode(dir)->i_sb);
  98         struct vboxsf_dir_info *sf_d = dir->private_data;
  99         struct shfl_dirinfo *info;
 100         struct vboxsf_dir_buf *b;
 101         unsigned int d_type;
 102         loff_t i, cur = 0;
 103         ino_t fake_ino;
 104         void *end;
 105         int err;
 106
 107         list_for_each_entry(b, &sf_d->info_list, head) {
 108 try_next_entry:
 109                 if (ctx->pos >= cur + b->entries) {
 110                         cur += b->entries;
 111                         continue;
 112                 }
 113
 114                 /*
 115                  * Note the vboxsf_dir_info objects we are iterating over here
 116                  * are variable sized, so the info pointer may end up being
 117                  * unaligned. This is how we get the data from the host.
 118                  * Since vboxsf is only supported on x86 machines this is not
 119                  * a problem.
 120                  */
 121                 for (i = 0, info = b->buf; i < ctx->pos - cur; i++) {
 122                         end = &info->name.string.utf8[info->name.size];
 123                         /* Only happens if the host gives us corrupt data */
 124                         if (WARN_ON(end > (b->buf + b->used)))
 125                                 return false;
 126                         info = end;
 127                 }
 128
 129                 end = &info->name.string.utf8[info->name.size];
 130                 if (WARN_ON(end > (b->buf + b->used)))
 131                         return false;
 132
 133                 /* Info now points to the right entry, emit it. */
 134                 d_type = vboxsf_get_d_type(info->info.attr.mode);
 135
 136                 /*
 137                  * On 32-bit systems pos is 64-bit signed, while ino is 32-bit
 138                  * unsigned so fake_ino may overflow, check for this.
 139                  */
 140                 if ((ino_t)(ctx->pos + 1) != (u64)(ctx->pos + 1)) {
 141                         vbg_err("vboxsf: fake ino overflow, truncating dir\n");
 142                         return false;
 143                 }
 144                 fake_ino = ctx->pos + 1;
 145
 146                 if (sbi->nls) {
 147                         char d_name[NAME_MAX];
 148
 149                         err = vboxsf_nlscpy(sbi, d_name, NAME_MAX,
 150                                             info->name.string.utf8,
 151                                             info->name.length);
 152                         if (err) {
 153                                 /* skip erroneous entry and proceed */
 154                                 ctx->pos += 1;
 155                                 goto try_next_entry;
 156                         }
 157
 158                         return dir_emit(ctx, d_name, strlen(d_name),
 159                                         fake_ino, d_type);
 160                 }
 161
 162                 return dir_emit(ctx, info->name.string.utf8, info->name.length,
 163                                 fake_ino, d_type);
 164         }
 165
 166         return false;
 167 }
 168
 169 static int vboxsf_dir_iterate(struct file *dir, struct dir_context *ctx)
 170 {
 171         bool emitted;
 172
 173         do {
 174                 emitted = vboxsf_dir_emit(dir, ctx);
 175                 if (emitted)
 176                         ctx->pos += 1;
 177         } while (emitted);
 178
 179         return 0;
 180 }
 181
 182 const struct file_operations vboxsf_dir_fops = {
 183         .open = vboxsf_dir_open,
 184         .iterate = vboxsf_dir_iterate,
 185         .release = vboxsf_dir_release,
 186         .read = generic_read_dir,
 187         .llseek = generic_file_llseek,
 188 };
 189
 190 /*
 191  * This is called during name resolution/lookup to check if the @dentry in
 192  * the cache is still valid. the job is handled by vboxsf_inode_revalidate.
 193  */
 194 static int vboxsf_dentry_revalidate(struct dentry *dentry, unsigned int flags)
 195 {
 196         if (flags & LOOKUP_RCU)
 197                 return -ECHILD;
 198
 199         if (d_really_is_positive(dentry))
 200                 return vboxsf_inode_revalidate(dentry) == 0;
 201         else
 202                 return vboxsf_stat_dentry(dentry, NULL) == -ENOENT;
 203 }
 204
 205 const struct dentry_operations vboxsf_dentry_ops = {
 206         .d_revalidate = vboxsf_dentry_revalidate
 207 };
 208
 209 /* iops */
 210
 211 static struct dentry *vboxsf_dir_lookup(struct inode *parent,
 212                                         struct dentry *dentry,
 213                                         unsigned int flags)
 214 {
 215         struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
 216         struct shfl_fsobjinfo fsinfo;
 217         struct inode *inode;
 218         int err;
 219
 220         dentry->d_time = jiffies;
 221
 222         err = vboxsf_stat_dentry(dentry, &fsinfo);
 223         if (err) {
 224                 inode = (err == -ENOENT) ? NULL : ERR_PTR(err);
 225         } else {
 226                 inode = vboxsf_new_inode(parent->i_sb);
 227                 if (!IS_ERR(inode))
 228                         vboxsf_init_inode(sbi, inode, &fsinfo);
 229         }
 230
 231         return d_splice_alias(inode, dentry);
 232 }
 233
 234 static int vboxsf_dir_instantiate(struct inode *parent, struct dentry *dentry,
 235                                   struct shfl_fsobjinfo *info)
 236 {
 237         struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
 238         struct vboxsf_inode *sf_i;
 239         struct inode *inode;
 240
 241         inode = vboxsf_new_inode(parent->i_sb);
 242         if (IS_ERR(inode))
 243                 return PTR_ERR(inode);
 244
 245         sf_i = VBOXSF_I(inode);
 246         /* The host may have given us different attr then requested */
 247         sf_i->force_restat = 1;
 248         vboxsf_init_inode(sbi, inode, info);
 249
 250         d_instantiate(dentry, inode);
 251
 252         return 0;
 253 }
 254
 255 static int vboxsf_dir_create(struct inode *parent, struct dentry *dentry,
 256                              umode_t mode, int is_dir)
 257 {
 258         struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
 259         struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
 260         struct shfl_createparms params = {};
 261         int err;
 262
 263         params.handle = SHFL_HANDLE_NIL;
 264         params.create_flags = SHFL_CF_ACT_CREATE_IF_NEW |
 265                               SHFL_CF_ACT_FAIL_IF_EXISTS |
 266                               SHFL_CF_ACCESS_READWRITE |
 267                               (is_dir ? SHFL_CF_DIRECTORY : 0);
 268         params.info.attr.mode = (mode & 0777) |
 269                                 (is_dir ? SHFL_TYPE_DIRECTORY : SHFL_TYPE_FILE);
 270         params.info.attr.additional = SHFLFSOBJATTRADD_NOTHING;
 271
 272         err = vboxsf_create_at_dentry(dentry, &params);
 273         if (err)
 274                 return err;
 275
 276         if (params.result != SHFL_FILE_CREATED)
 277                 return -EPERM;
 278
 279         vboxsf_close(sbi->root, params.handle);
 280
 281         err = vboxsf_dir_instantiate(parent, dentry, &params.info);
 282         if (err)
 283                 return err;
 284
 285         /* parent directory access/change time changed */
 286         sf_parent_i->force_restat = 1;
 287
 288         return 0;
 289 }
 290
 291 static int vboxsf_dir_mkfile(struct inode *parent, struct dentry *dentry,
 292                              umode_t mode, bool excl)
 293 {
 294         return vboxsf_dir_create(parent, dentry, mode, 0);
 295 }
 296
 297 static int vboxsf_dir_mkdir(struct inode *parent, struct dentry *dentry,
 298                             umode_t mode)
 299 {
 300         return vboxsf_dir_create(parent, dentry, mode, 1);
 301 }
 302
 303 static int vboxsf_dir_unlink(struct inode *parent, struct dentry *dentry)
 304 {
 305         struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
 306         struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
 307         struct inode *inode = d_inode(dentry);
 308         struct shfl_string *path;
 309         u32 flags;
 310         int err;
 311
 312         if (S_ISDIR(inode->i_mode))
 313                 flags = SHFL_REMOVE_DIR;
 314         else
 315                 flags = SHFL_REMOVE_FILE;
 316
 317         if (S_ISLNK(inode->i_mode))
 318                 flags |= SHFL_REMOVE_SYMLINK;
 319
 320         path = vboxsf_path_from_dentry(sbi, dentry);
 321         if (IS_ERR(path))
 322                 return PTR_ERR(path);
 323
 324         err = vboxsf_remove(sbi->root, path, flags);
 325         __putname(path);
 326         if (err)
 327                 return err;
 328
 329         /* parent directory access/change time changed */
 330         sf_parent_i->force_restat = 1;
 331
 332         return 0;
 333 }
 334
 335 static int vboxsf_dir_rename(struct inode *old_parent,
 336                              struct dentry *old_dentry,
 337                              struct inode *new_parent,
 338                              struct dentry *new_dentry,
 339                              unsigned int flags)
 340 {
 341         struct vboxsf_sbi *sbi = VBOXSF_SBI(old_parent->i_sb);
 342         struct vboxsf_inode *sf_old_parent_i = VBOXSF_I(old_parent);
 343         struct vboxsf_inode *sf_new_parent_i = VBOXSF_I(new_parent);
 344         u32 shfl_flags = SHFL_RENAME_FILE | SHFL_RENAME_REPLACE_IF_EXISTS;
 345         struct shfl_string *old_path, *new_path;
 346         int err;
 347
 348         if (flags)
 349                 return -EINVAL;
 350
 351         old_path = vboxsf_path_from_dentry(sbi, old_dentry);
 352         if (IS_ERR(old_path))
 353                 return PTR_ERR(old_path);
 354
 355         new_path = vboxsf_path_from_dentry(sbi, new_dentry);
 356         if (IS_ERR(new_path)) {
 357                 err = PTR_ERR(new_path);
 358                 goto err_put_old_path;
 359         }
 360
 361         if (d_inode(old_dentry)->i_mode & S_IFDIR)
 362                 shfl_flags = 0;
 363
 364         err = vboxsf_rename(sbi->root, old_path, new_path, shfl_flags);
 365         if (err == 0) {
 366                 /* parent directories access/change time changed */
 367                 sf_new_parent_i->force_restat = 1;
 368                 sf_old_parent_i->force_restat = 1;
 369         }
 370
 371         __putname(new_path);
 372 err_put_old_path:
 373         __putname(old_path);
 374         return err;
 375 }
 376
 377 static int vboxsf_dir_symlink(struct inode *parent, struct dentry *dentry,
 378                               const char *symname)
 379 {
 380         struct vboxsf_inode *sf_parent_i = VBOXSF_I(parent);
 381         struct vboxsf_sbi *sbi = VBOXSF_SBI(parent->i_sb);
 382         int symname_size = strlen(symname) + 1;
 383         struct shfl_string *path, *ssymname;
 384         struct shfl_fsobjinfo info;
 385         int err;
 386
 387         path = vboxsf_path_from_dentry(sbi, dentry);
 388         if (IS_ERR(path))
 389                 return PTR_ERR(path);
 390
 391         ssymname = kmalloc(SHFLSTRING_HEADER_SIZE + symname_size, GFP_KERNEL);
 392         if (!ssymname) {
 393                 __putname(path);
 394                 return -ENOMEM;
 395         }
 396         ssymname->length = symname_size - 1;
 397         ssymname->size = symname_size;
 398         memcpy(ssymname->string.utf8, symname, symname_size);
 399
 400         err = vboxsf_symlink(sbi->root, path, ssymname, &info);
 401         kfree(ssymname);
 402         __putname(path);
 403         if (err) {
 404                 /* -EROFS means symlinks are note support -> -EPERM */
 405                 return (err == -EROFS) ? -EPERM : err;
 406         }
 407
 408         err = vboxsf_dir_instantiate(parent, dentry, &info);
 409         if (err)
 410                 return err;
 411
 412         /* parent directory access/change time changed */
 413         sf_parent_i->force_restat = 1;
 414         return 0;
 415 }
 416
 417 const struct inode_operations vboxsf_dir_iops = {
 418         .lookup  = vboxsf_dir_lookup,
 419         .create  = vboxsf_dir_mkfile,
 420         .mkdir   = vboxsf_dir_mkdir,
 421         .rmdir   = vboxsf_dir_unlink,
 422         .unlink  = vboxsf_dir_unlink,
 423         .rename  = vboxsf_dir_rename,
 424         .symlink = vboxsf_dir_symlink,
 425         .getattr = vboxsf_getattr,
 426         .setattr = vboxsf_setattr,
 427 };