hw/9pfs/9p-synth.c

   1 /*
   2  * 9p synthetic file system support
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *  Malahal Naineni <malahal@us.ibm.com>
   8  *  Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2.  See
  11  * the COPYING file in the top-level directory.
  12  *
  13  */
  14
  15 /*
  16  * Not so fast! You might want to read the 9p developer docs first:
  17  * https://wiki.qemu.org/Documentation/9p
  18  */
  19
  20 #include "qemu/osdep.h"
  21 #include "9p.h"
  22 #include "fsdev/qemu-fsdev.h"
  23 #include "9p-synth.h"
  24 #include "qemu/rcu.h"
  25 #include "qemu/rcu_queue.h"
  26 #include "qemu/cutils.h"
  27 #include "sysemu/qtest.h"
  28
  29 /* Root node for synth file system */
  30 static V9fsSynthNode synth_root = {
  31     .name = "/",
  32     .actual_attr = {
  33         .mode = 0555 | S_IFDIR,
  34         .nlink = 1,
  35     },
  36     .attr = &synth_root.actual_attr,
  37 };
  38
  39 static QemuMutex  synth_mutex;
  40 static int synth_node_count;
  41 /* set to 1 when the synth fs is ready */
  42 static int synth_fs;
  43
  44 static V9fsSynthNode *v9fs_add_dir_node(V9fsSynthNode *parent, int mode,
  45                                         const char *name,
  46                                         V9fsSynthNodeAttr *attr, int inode)
  47 {
  48     V9fsSynthNode *node;
  49
  50     /* Add directory type and remove write bits */
  51     mode = ((mode & 0777) | S_IFDIR) & ~(S_IWUSR | S_IWGRP | S_IWOTH);
  52     node = g_malloc0(sizeof(V9fsSynthNode));
  53     if (attr) {
  54         /* We are adding .. or . entries */
  55         node->attr = attr;
  56         node->attr->nlink++;
  57     } else {
  58         node->attr = &node->actual_attr;
  59         node->attr->inode = inode;
  60         node->attr->nlink = 1;
  61         /* We don't allow write to directories */
  62         node->attr->mode   = mode;
  63         node->attr->write = NULL;
  64         node->attr->read  = NULL;
  65     }
  66     node->private = node;
  67     pstrcpy(node->name, sizeof(node->name), name);
  68     QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling);
  69     return node;
  70 }
  71
  72 int qemu_v9fs_synth_mkdir(V9fsSynthNode *parent, int mode,
  73                           const char *name, V9fsSynthNode **result)
  74 {
  75     int ret;
  76     V9fsSynthNode *node, *tmp;
  77
  78     if (!synth_fs) {
  79         return EAGAIN;
  80     }
  81     if (!name || (strlen(name) >= NAME_MAX)) {
  82         return EINVAL;
  83     }
  84     if (!parent) {
  85         parent = &synth_root;
  86     }
  87     QEMU_LOCK_GUARD(&synth_mutex);
  88     QLIST_FOREACH(tmp, &parent->child, sibling) {
  89         if (!strcmp(tmp->name, name)) {
  90             ret = EEXIST;
  91             return ret;
  92         }
  93     }
  94     /* Add the name */
  95     node = v9fs_add_dir_node(parent, mode, name, NULL, synth_node_count++);
  96     v9fs_add_dir_node(node, parent->attr->mode, "..",
  97                       parent->attr, parent->attr->inode);
  98     v9fs_add_dir_node(node, node->attr->mode, ".",
  99                       node->attr, node->attr->inode);
 100     *result = node;
 101     ret = 0;
 102     return ret;
 103 }
 104
 105 int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int mode,
 106                              const char *name, v9fs_synth_read read,
 107                              v9fs_synth_write write, void *arg)
 108 {
 109     int ret;
 110     V9fsSynthNode *node, *tmp;
 111
 112     if (!synth_fs) {
 113         return EAGAIN;
 114     }
 115     if (!name || (strlen(name) >= NAME_MAX)) {
 116         return EINVAL;
 117     }
 118     if (!parent) {
 119         parent = &synth_root;
 120     }
 121
 122     QEMU_LOCK_GUARD(&synth_mutex);
 123     QLIST_FOREACH(tmp, &parent->child, sibling) {
 124         if (!strcmp(tmp->name, name)) {
 125             ret = EEXIST;
 126             return ret;
 127         }
 128     }
 129     /* Add file type and remove write bits */
 130     mode = ((mode & 0777) | S_IFREG);
 131     node = g_malloc0(sizeof(V9fsSynthNode));
 132     node->attr         = &node->actual_attr;
 133     node->attr->inode  = synth_node_count++;
 134     node->attr->nlink  = 1;
 135     node->attr->read   = read;
 136     node->attr->write  = write;
 137     node->attr->mode   = mode;
 138     node->private      = arg;
 139     pstrcpy(node->name, sizeof(node->name), name);
 140     QLIST_INSERT_HEAD_RCU(&parent->child, node, sibling);
 141     ret = 0;
 142     return ret;
 143 }
 144
 145 static void synth_fill_statbuf(V9fsSynthNode *node, struct stat *stbuf)
 146 {
 147     stbuf->st_dev = 0;
 148     stbuf->st_ino = node->attr->inode;
 149     stbuf->st_mode = node->attr->mode;
 150     stbuf->st_nlink = node->attr->nlink;
 151     stbuf->st_uid = 0;
 152     stbuf->st_gid = 0;
 153     stbuf->st_rdev = 0;
 154     stbuf->st_size = 0;
 155     stbuf->st_blksize = 0;
 156     stbuf->st_blocks = 0;
 157     stbuf->st_atime = 0;
 158     stbuf->st_mtime = 0;
 159     stbuf->st_ctime = 0;
 160 }
 161
 162 static int synth_lstat(FsContext *fs_ctx,
 163                             V9fsPath *fs_path, struct stat *stbuf)
 164 {
 165     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 166
 167     synth_fill_statbuf(node, stbuf);
 168     return 0;
 169 }
 170
 171 static int synth_fstat(FsContext *fs_ctx, int fid_type,
 172                             V9fsFidOpenState *fs, struct stat *stbuf)
 173 {
 174     V9fsSynthOpenState *synth_open = fs->private;
 175     synth_fill_statbuf(synth_open->node, stbuf);
 176     return 0;
 177 }
 178
 179 static int synth_opendir(FsContext *ctx,
 180                              V9fsPath *fs_path, V9fsFidOpenState *fs)
 181 {
 182     V9fsSynthOpenState *synth_open;
 183     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 184
 185     /*
 186      * V9fsSynthOpenState contains 'struct dirent' which have OS-specific
 187      * properties, thus it's zero cleared on allocation here and below
 188      * in synth_open.
 189      */
 190     synth_open = g_new0(V9fsSynthOpenState, 1);
 191     synth_open->node = node;
 192     node->open_count++;
 193     fs->private = synth_open;
 194     return 0;
 195 }
 196
 197 static int synth_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 198 {
 199     V9fsSynthOpenState *synth_open = fs->private;
 200     V9fsSynthNode *node = synth_open->node;
 201
 202     node->open_count--;
 203     g_free(synth_open);
 204     fs->private = NULL;
 205     return 0;
 206 }
 207
 208 static off_t synth_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 209 {
 210     V9fsSynthOpenState *synth_open = fs->private;
 211     return synth_open->offset;
 212 }
 213
 214 static void synth_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 215 {
 216     V9fsSynthOpenState *synth_open = fs->private;
 217     synth_open->offset = off;
 218 }
 219
 220 static void synth_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 221 {
 222     synth_seekdir(ctx, fs, 0);
 223 }
 224
 225 static void synth_direntry(V9fsSynthNode *node,
 226                                 struct dirent *entry, off_t off)
 227 {
 228     size_t sz = strlen(node->name) + 1;
 229     /*
 230      * 'entry' is always inside of V9fsSynthOpenState which have NAME_MAX
 231      * back padding. Ensure we do not overflow it.
 232      */
 233     g_assert(sizeof(struct dirent) + NAME_MAX >=
 234              offsetof(struct dirent, d_name) + sz);
 235     memcpy(entry->d_name, node->name, sz);
 236     entry->d_ino = node->attr->inode;
 237     entry->d_off = off + 1;
 238 }
 239
 240 static struct dirent *synth_get_dentry(V9fsSynthNode *dir,
 241                                             struct dirent *entry, off_t off)
 242 {
 243     int i = 0;
 244     V9fsSynthNode *node;
 245
 246     rcu_read_lock();
 247     QLIST_FOREACH(node, &dir->child, sibling) {
 248         /* This is the off child of the directory */
 249         if (i == off) {
 250             break;
 251         }
 252         i++;
 253     }
 254     rcu_read_unlock();
 255     if (!node) {
 256         /* end of directory */
 257         return NULL;
 258     }
 259     synth_direntry(node, entry, off);
 260     return entry;
 261 }
 262
 263 static struct dirent *synth_readdir(FsContext *ctx, V9fsFidOpenState *fs)
 264 {
 265     struct dirent *entry;
 266     V9fsSynthOpenState *synth_open = fs->private;
 267     V9fsSynthNode *node = synth_open->node;
 268     entry = synth_get_dentry(node, &synth_open->dent, synth_open->offset);
 269     if (entry) {
 270         synth_open->offset++;
 271     }
 272     return entry;
 273 }
 274
 275 static int synth_open(FsContext *ctx, V9fsPath *fs_path,
 276                            int flags, V9fsFidOpenState *fs)
 277 {
 278     V9fsSynthOpenState *synth_open;
 279     V9fsSynthNode *node = *(V9fsSynthNode **)fs_path->data;
 280
 281     synth_open = g_new0(V9fsSynthOpenState, 1);
 282     synth_open->node = node;
 283     node->open_count++;
 284     fs->private = synth_open;
 285     return 0;
 286 }
 287
 288 static int synth_open2(FsContext *fs_ctx, V9fsPath *dir_path,
 289                             const char *name, int flags,
 290                             FsCred *credp, V9fsFidOpenState *fs)
 291 {
 292     errno = ENOSYS;
 293     return -1;
 294 }
 295
 296 static int synth_close(FsContext *ctx, V9fsFidOpenState *fs)
 297 {
 298     V9fsSynthOpenState *synth_open = fs->private;
 299     V9fsSynthNode *node = synth_open->node;
 300
 301     node->open_count--;
 302     g_free(synth_open);
 303     fs->private = NULL;
 304     return 0;
 305 }
 306
 307 static ssize_t synth_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
 308                                   const struct iovec *iov,
 309                                   int iovcnt, off_t offset)
 310 {
 311     int i, count = 0, wcount;
 312     V9fsSynthOpenState *synth_open = fs->private;
 313     V9fsSynthNode *node = synth_open->node;
 314     if (!node->attr->write) {
 315         errno = EPERM;
 316         return -1;
 317     }
 318     for (i = 0; i < iovcnt; i++) {
 319         wcount = node->attr->write(iov[i].iov_base, iov[i].iov_len,
 320                                    offset, node->private);
 321         offset += wcount;
 322         count  += wcount;
 323         /* If we wrote less than requested. we are done */
 324         if (wcount < iov[i].iov_len) {
 325             break;
 326         }
 327     }
 328     return count;
 329 }
 330
 331 static ssize_t synth_preadv(FsContext *ctx, V9fsFidOpenState *fs,
 332                                  const struct iovec *iov,
 333                                  int iovcnt, off_t offset)
 334 {
 335     int i, count = 0, rcount;
 336     V9fsSynthOpenState *synth_open = fs->private;
 337     V9fsSynthNode *node = synth_open->node;
 338     if (!node->attr->read) {
 339         errno = EPERM;
 340         return -1;
 341     }
 342     for (i = 0; i < iovcnt; i++) {
 343         rcount = node->attr->read(iov[i].iov_base, iov[i].iov_len,
 344                                   offset, node->private);
 345         offset += rcount;
 346         count  += rcount;
 347         /* If we read less than requested. we are done */
 348         if (rcount < iov[i].iov_len) {
 349             break;
 350         }
 351     }
 352     return count;
 353 }
 354
 355 static int synth_truncate(FsContext *ctx, V9fsPath *path, off_t offset)
 356 {
 357     errno = ENOSYS;
 358     return -1;
 359 }
 360
 361 static int synth_chmod(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 362 {
 363     errno = EPERM;
 364     return -1;
 365 }
 366
 367 static int synth_mknod(FsContext *fs_ctx, V9fsPath *path,
 368                        const char *buf, FsCred *credp)
 369 {
 370     errno = EPERM;
 371     return -1;
 372 }
 373
 374 static int synth_mkdir(FsContext *fs_ctx, V9fsPath *path,
 375                        const char *buf, FsCred *credp)
 376 {
 377     errno = EPERM;
 378     return -1;
 379 }
 380
 381 static ssize_t synth_readlink(FsContext *fs_ctx, V9fsPath *path,
 382                                    char *buf, size_t bufsz)
 383 {
 384     errno = ENOSYS;
 385     return -1;
 386 }
 387
 388 static int synth_symlink(FsContext *fs_ctx, const char *oldpath,
 389                               V9fsPath *newpath, const char *buf, FsCred *credp)
 390 {
 391     errno = EPERM;
 392     return -1;
 393 }
 394
 395 static int synth_link(FsContext *fs_ctx, V9fsPath *oldpath,
 396                            V9fsPath *newpath, const char *buf)
 397 {
 398     errno = EPERM;
 399     return -1;
 400 }
 401
 402 static int synth_rename(FsContext *ctx, const char *oldpath,
 403                              const char *newpath)
 404 {
 405     errno = EPERM;
 406     return -1;
 407 }
 408
 409 static int synth_chown(FsContext *fs_ctx, V9fsPath *path, FsCred *credp)
 410 {
 411     errno = EPERM;
 412     return -1;
 413 }
 414
 415 static int synth_utimensat(FsContext *fs_ctx, V9fsPath *path,
 416                                 const struct timespec *buf)
 417 {
 418     errno = EPERM;
 419     return 0;
 420 }
 421
 422 static int synth_remove(FsContext *ctx, const char *path)
 423 {
 424     errno = EPERM;
 425     return -1;
 426 }
 427
 428 static int synth_fsync(FsContext *ctx, int fid_type,
 429                             V9fsFidOpenState *fs, int datasync)
 430 {
 431     errno = ENOSYS;
 432     return 0;
 433 }
 434
 435 static int synth_statfs(FsContext *s, V9fsPath *fs_path,
 436                              struct statfs *stbuf)
 437 {
 438     stbuf->f_type = 0xABCD;
 439     stbuf->f_bsize = 512;
 440     stbuf->f_blocks = 0;
 441     stbuf->f_files = synth_node_count;
 442     stbuf->f_namelen = NAME_MAX;
 443     return 0;
 444 }
 445
 446 static ssize_t synth_lgetxattr(FsContext *ctx, V9fsPath *path,
 447                                     const char *name, void *value, size_t size)
 448 {
 449     errno = ENOTSUP;
 450     return -1;
 451 }
 452
 453 static ssize_t synth_llistxattr(FsContext *ctx, V9fsPath *path,
 454                                      void *value, size_t size)
 455 {
 456     errno = ENOTSUP;
 457     return -1;
 458 }
 459
 460 static int synth_lsetxattr(FsContext *ctx, V9fsPath *path,
 461                                 const char *name, void *value,
 462                                 size_t size, int flags)
 463 {
 464     errno = ENOTSUP;
 465     return -1;
 466 }
 467
 468 static int synth_lremovexattr(FsContext *ctx,
 469                                    V9fsPath *path, const char *name)
 470 {
 471     errno = ENOTSUP;
 472     return -1;
 473 }
 474
 475 static int synth_name_to_path(FsContext *ctx, V9fsPath *dir_path,
 476                                    const char *name, V9fsPath *target)
 477 {
 478     V9fsSynthNode *node;
 479     V9fsSynthNode *dir_node;
 480
 481     /* "." and ".." are not allowed */
 482     if (!strcmp(name, ".") || !strcmp(name, "..")) {
 483         errno = EINVAL;
 484         return -1;
 485
 486     }
 487     if (!dir_path) {
 488         dir_node = &synth_root;
 489     } else {
 490         dir_node = *(V9fsSynthNode **)dir_path->data;
 491     }
 492     if (!strcmp(name, "/")) {
 493         node = dir_node;
 494         goto out;
 495     }
 496     /* search for the name in the childern */
 497     rcu_read_lock();
 498     QLIST_FOREACH(node, &dir_node->child, sibling) {
 499         if (!strcmp(node->name, name)) {
 500             break;
 501         }
 502     }
 503     rcu_read_unlock();
 504
 505     if (!node) {
 506         errno = ENOENT;
 507         return -1;
 508     }
 509 out:
 510     /* Copy the node pointer to fid */
 511     g_free(target->data);
 512     target->data = g_memdup(&node, sizeof(void *));
 513     target->size = sizeof(void *);
 514     return 0;
 515 }
 516
 517 static int synth_renameat(FsContext *ctx, V9fsPath *olddir,
 518                                const char *old_name, V9fsPath *newdir,
 519                                const char *new_name)
 520 {
 521     errno = EPERM;
 522     return -1;
 523 }
 524
 525 static int synth_unlinkat(FsContext *ctx, V9fsPath *dir,
 526                                const char *name, int flags)
 527 {
 528     errno = EPERM;
 529     return -1;
 530 }
 531
 532 static ssize_t v9fs_synth_qtest_write(void *buf, int len, off_t offset,
 533                                       void *arg)
 534 {
 535     return 1;
 536 }
 537
 538 static ssize_t v9fs_synth_qtest_flush_write(void *buf, int len, off_t offset,
 539                                             void *arg)
 540 {
 541     bool should_block = !!*(uint8_t *)buf;
 542
 543     if (should_block) {
 544         /* This will cause the server to call us again until we're cancelled */
 545         errno = EINTR;
 546         return -1;
 547     }
 548
 549     return 1;
 550 }
 551
 552 static int synth_init(FsContext *ctx, Error **errp)
 553 {
 554     QLIST_INIT(&synth_root.child);
 555     qemu_mutex_init(&synth_mutex);
 556
 557     /* Add "." and ".." entries for root */
 558     v9fs_add_dir_node(&synth_root, synth_root.attr->mode,
 559                       "..", synth_root.attr, synth_root.attr->inode);
 560     v9fs_add_dir_node(&synth_root, synth_root.attr->mode,
 561                       ".", synth_root.attr, synth_root.attr->inode);
 562
 563     /* Mark the subsystem is ready for use */
 564     synth_fs = 1;
 565
 566     if (qtest_enabled()) {
 567         V9fsSynthNode *node = NULL;
 568         int i, ret;
 569
 570         /* Directory hierarchy for WALK test */
 571         for (i = 0; i < P9_MAXWELEM; i++) {
 572             char *name = g_strdup_printf(QTEST_V9FS_SYNTH_WALK_FILE, i);
 573
 574             ret = qemu_v9fs_synth_mkdir(node, 0700, name, &node);
 575             assert(!ret);
 576             g_free(name);
 577         }
 578
 579         /* File for LOPEN test */
 580         ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_LOPEN_FILE,
 581                                        NULL, NULL, ctx);
 582         assert(!ret);
 583
 584         /* File for WRITE test */
 585         ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_WRITE_FILE,
 586                                        NULL, v9fs_synth_qtest_write, ctx);
 587         assert(!ret);
 588
 589         /* File for FLUSH test */
 590         ret = qemu_v9fs_synth_add_file(NULL, 0, QTEST_V9FS_SYNTH_FLUSH_FILE,
 591                                        NULL, v9fs_synth_qtest_flush_write,
 592                                        ctx);
 593         assert(!ret);
 594
 595         /* Directory for READDIR test */
 596         {
 597             V9fsSynthNode *dir = NULL;
 598             ret = qemu_v9fs_synth_mkdir(
 599                 NULL, 0700, QTEST_V9FS_SYNTH_READDIR_DIR, &dir
 600             );
 601             assert(!ret);
 602             for (i = 0; i < QTEST_V9FS_SYNTH_READDIR_NFILES; ++i) {
 603                 char *name = g_strdup_printf(
 604                     QTEST_V9FS_SYNTH_READDIR_FILE, i
 605                 );
 606                 ret = qemu_v9fs_synth_add_file(
 607                     dir, 0, name, NULL, NULL, ctx
 608                 );
 609                 assert(!ret);
 610                 g_free(name);
 611             }
 612         }
 613     }
 614
 615     return 0;
 616 }
 617
 618 FileOperations synth_ops = {
 619     .init         = synth_init,
 620     .lstat        = synth_lstat,
 621     .readlink     = synth_readlink,
 622     .close        = synth_close,
 623     .closedir     = synth_closedir,
 624     .open         = synth_open,
 625     .opendir      = synth_opendir,
 626     .rewinddir    = synth_rewinddir,
 627     .telldir      = synth_telldir,
 628     .readdir      = synth_readdir,
 629     .seekdir      = synth_seekdir,
 630     .preadv       = synth_preadv,
 631     .pwritev      = synth_pwritev,
 632     .chmod        = synth_chmod,
 633     .mknod        = synth_mknod,
 634     .mkdir        = synth_mkdir,
 635     .fstat        = synth_fstat,
 636     .open2        = synth_open2,
 637     .symlink      = synth_symlink,
 638     .link         = synth_link,
 639     .truncate     = synth_truncate,
 640     .rename       = synth_rename,
 641     .chown        = synth_chown,
 642     .utimensat    = synth_utimensat,
 643     .remove       = synth_remove,
 644     .fsync        = synth_fsync,
 645     .statfs       = synth_statfs,
 646     .lgetxattr    = synth_lgetxattr,
 647     .llistxattr   = synth_llistxattr,
 648     .lsetxattr    = synth_lsetxattr,
 649     .lremovexattr = synth_lremovexattr,
 650     .name_to_path = synth_name_to_path,
 651     .renameat     = synth_renameat,
 652     .unlinkat     = synth_unlinkat,
 653 };