hw/9pfs/virtio-9p-handle.c

   1 /*
   2  * Virtio 9p handle callback
   3  *
   4  * Copyright IBM, Corp. 2011
   5  *
   6  * Authors:
   7  *    Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include "hw/virtio.h"
  15 #include "virtio-9p.h"
  16 #include "virtio-9p-xattr.h"
  17 #include <arpa/inet.h>
  18 #include <pwd.h>
  19 #include <grp.h>
  20 #include <sys/socket.h>
  21 #include <sys/un.h>
  22 #include <attr/xattr.h>
  23 #include <unistd.h>
  24 #include <linux/fs.h>
  25 #ifdef CONFIG_LINUX_MAGIC_H
  26 #include <linux/magic.h>
  27 #endif
  28 #include <sys/ioctl.h>
  29
  30 #ifndef XFS_SUPER_MAGIC
  31 #define XFS_SUPER_MAGIC  0x58465342
  32 #endif
  33 #ifndef EXT2_SUPER_MAGIC
  34 #define EXT2_SUPER_MAGIC 0xEF53
  35 #endif
  36 #ifndef REISERFS_SUPER_MAGIC
  37 #define REISERFS_SUPER_MAGIC 0x52654973
  38 #endif
  39 #ifndef BTRFS_SUPER_MAGIC
  40 #define BTRFS_SUPER_MAGIC 0x9123683E
  41 #endif
  42
  43 struct handle_data {
  44     int mountfd;
  45     int handle_bytes;
  46 };
  47
  48 #ifdef CONFIG_OPEN_BY_HANDLE
  49 static inline int name_to_handle(int dirfd, const char *name,
  50                                  struct file_handle *fh, int *mnt_id, int flags)
  51 {
  52     return name_to_handle_at(dirfd, name, fh, mnt_id, flags);
  53 }
  54
  55 static inline int open_by_handle(int mountfd, const char *fh, int flags)
  56 {
  57     return open_by_handle_at(mountfd, (struct file_handle *)fh, flags);
  58 }
  59 #else
  60
  61 struct file_handle {
  62     unsigned int handle_bytes;
  63     int handle_type;
  64     unsigned char handle[0];
  65 };
  66
  67 #ifndef AT_EMPTY_PATH
  68 #define AT_EMPTY_PATH   0x1000  /* Allow empty relative pathname */
  69 #endif
  70 #ifndef O_PATH
  71 #define O_PATH    010000000
  72 #endif
  73
  74 static inline int name_to_handle(int dirfd, const char *name,
  75                                  struct file_handle *fh, int *mnt_id, int flags)
  76 {
  77     errno = ENOSYS;
  78     return -1;
  79 }
  80
  81 static inline int open_by_handle(int mountfd, const char *fh, int flags)
  82 {
  83     errno = ENOSYS;
  84     return -1;
  85 }
  86 #endif
  87
  88 static int handle_update_file_cred(int dirfd, const char *name, FsCred *credp)
  89 {
  90     int fd, ret;
  91     fd = openat(dirfd, name, O_NONBLOCK | O_NOFOLLOW);;
  92     if (fd < 0) {
  93         return fd;
  94     }
  95     ret = fchmod(fd, credp->fc_mode & 07777);
  96     if (ret < 0) {
  97         goto err_out;
  98     }
  99     ret = fchownat(fd, "", credp->fc_uid, credp->fc_gid, AT_EMPTY_PATH);
 100 err_out:
 101     close(fd);
 102     return ret;
 103 }
 104
 105
 106 static int handle_lstat(FsContext *fs_ctx, V9fsPath *fs_path,
 107                         struct stat *stbuf)
 108 {
 109     int fd, ret;
 110     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 111
 112     fd = open_by_handle(data->mountfd, fs_path->data, O_PATH);
 113     if (fd < 0) {
 114         return fd;
 115     }
 116     ret = fstatat(fd, "", stbuf, AT_EMPTY_PATH);
 117     close(fd);
 118     return ret;
 119 }
 120
 121 static ssize_t handle_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
 122                                char *buf, size_t bufsz)
 123 {
 124     int fd, ret;
 125     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 126
 127     fd = open_by_handle(data->mountfd, fs_path->data, O_PATH);
 128     if (fd < 0) {
 129         return fd;
 130     }
 131     ret = readlinkat(fd, "", buf, bufsz);
 132     close(fd);
 133     return ret;
 134 }
 135
 136 static int handle_close(FsContext *ctx, V9fsFidOpenState *fs)
 137 {
 138     return close(fs->fd);
 139 }
 140
 141 static int handle_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 142 {
 143     return closedir(fs->dir);
 144 }
 145
 146 static int handle_open(FsContext *ctx, V9fsPath *fs_path,
 147                        int flags, V9fsFidOpenState *fs)
 148 {
 149     struct handle_data *data = (struct handle_data *)ctx->private;
 150
 151     fs->fd = open_by_handle(data->mountfd, fs_path->data, flags);
 152     return fs->fd;
 153 }
 154
 155 static int handle_opendir(FsContext *ctx,
 156                           V9fsPath *fs_path, V9fsFidOpenState *fs)
 157 {
 158     int ret;
 159     ret = handle_open(ctx, fs_path, O_DIRECTORY, fs);
 160     if (ret < 0) {
 161         return -1;
 162     }
 163     fs->dir = fdopendir(ret);
 164     if (!fs->dir) {
 165         return -1;
 166     }
 167     return 0;
 168 }
 169
 170 static void handle_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 171 {
 172     return rewinddir(fs->dir);
 173 }
 174
 175 static off_t handle_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 176 {
 177     return telldir(fs->dir);
 178 }
 179
 180 static int handle_readdir_r(FsContext *ctx, V9fsFidOpenState *fs,
 181                             struct dirent *entry,
 182                             struct dirent **result)
 183 {
 184     return readdir_r(fs->dir, entry, result);
 185 }
 186
 187 static void handle_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 188 {
 189     return seekdir(fs->dir, off);
 190 }
 191
 192 static ssize_t handle_preadv(FsContext *ctx, V9fsFidOpenState *fs,
 193                              const struct iovec *iov,
 194                              int iovcnt, off_t offset)
 195 {
 196 #ifdef CONFIG_PREADV
 197     return preadv(fs->fd, iov, iovcnt, offset);
 198 #else
 199     int err = lseek(fs->fd, offset, SEEK_SET);
 200     if (err == -1) {
 201         return err;
 202     } else {
 203         return readv(fs->fd, iov, iovcnt);
 204     }
 205 #endif
 206 }
 207
 208 static ssize_t handle_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
 209                               const struct iovec *iov,
 210                               int iovcnt, off_t offset)
 211 {
 212     ssize_t ret;
 213 #ifdef CONFIG_PREADV
 214     ret = pwritev(fs->fd, iov, iovcnt, offset);
 215 #else
 216     int err = lseek(fs->fd, offset, SEEK_SET);
 217     if (err == -1) {
 218         return err;
 219     } else {
 220         ret = writev(fs->fd, iov, iovcnt);
 221     }
 222 #endif
 223 #ifdef CONFIG_SYNC_FILE_RANGE
 224     if (ret > 0 && ctx->export_flags & V9FS_IMMEDIATE_WRITEOUT) {
 225         /*
 226          * Initiate a writeback. This is not a data integrity sync.
 227          * We want to ensure that we don't leave dirty pages in the cache
 228          * after write when writeout=immediate is sepcified.
 229          */
 230         sync_file_range(fs->fd, offset, ret,
 231                         SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE);
 232     }
 233 #endif
 234     return ret;
 235 }
 236
 237 static int handle_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
 238 {
 239     int fd, ret;
 240     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 241
 242     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
 243     if (fd < 0) {
 244         return fd;
 245     }
 246     ret = fchmod(fd, credp->fc_mode);
 247     close(fd);
 248     return ret;
 249 }
 250
 251 static int handle_mknod(FsContext *fs_ctx, V9fsPath *dir_path,
 252                        const char *name, FsCred *credp)
 253 {
 254     int dirfd, ret;
 255     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 256
 257     dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
 258     if (dirfd < 0) {
 259         return dirfd;
 260     }
 261     ret = mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev);
 262     if (!ret) {
 263         ret = handle_update_file_cred(dirfd, name, credp);
 264     }
 265     close(dirfd);
 266     return ret;
 267 }
 268
 269 static int handle_mkdir(FsContext *fs_ctx, V9fsPath *dir_path,
 270                        const char *name, FsCred *credp)
 271 {
 272     int dirfd, ret;
 273     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 274
 275     dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
 276     if (dirfd < 0) {
 277         return dirfd;
 278     }
 279     ret = mkdirat(dirfd, name, credp->fc_mode);
 280     if (!ret) {
 281         ret = handle_update_file_cred(dirfd, name, credp);
 282     }
 283     close(dirfd);
 284     return ret;
 285 }
 286
 287 static int handle_fstat(FsContext *fs_ctx, V9fsFidOpenState *fs,
 288                         struct stat *stbuf)
 289 {
 290     return fstat(fs->fd, stbuf);
 291 }
 292
 293 static int handle_open2(FsContext *fs_ctx, V9fsPath *dir_path, const char *name,
 294                         int flags, FsCred *credp, V9fsFidOpenState *fs)
 295 {
 296     int ret;
 297     int dirfd, fd;
 298     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 299
 300     dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
 301     if (dirfd < 0) {
 302         return dirfd;
 303     }
 304     fd = openat(dirfd, name, flags | O_NOFOLLOW, credp->fc_mode);
 305     if (fd >= 0) {
 306         ret = handle_update_file_cred(dirfd, name, credp);
 307         if (ret < 0) {
 308             close(fd);
 309             fd = ret;
 310         } else {
 311             fs->fd = fd;
 312         }
 313     }
 314     close(dirfd);
 315     return fd;
 316 }
 317
 318
 319 static int handle_symlink(FsContext *fs_ctx, const char *oldpath,
 320                           V9fsPath *dir_path, const char *name, FsCred *credp)
 321 {
 322     int fd, dirfd, ret;
 323     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 324
 325     dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
 326     if (dirfd < 0) {
 327         return dirfd;
 328     }
 329     ret = symlinkat(oldpath, dirfd, name);
 330     if (!ret) {
 331         fd = openat(dirfd, name, O_PATH | O_NOFOLLOW);
 332         if (fd < 0) {
 333             ret = fd;
 334             goto err_out;
 335         }
 336         ret = fchownat(fd, "", credp->fc_uid, credp->fc_gid, AT_EMPTY_PATH);
 337         close(fd);
 338     }
 339 err_out:
 340     close(dirfd);
 341     return ret;
 342 }
 343
 344 static int handle_link(FsContext *ctx, V9fsPath *oldpath,
 345                        V9fsPath *dirpath, const char *name)
 346 {
 347     int oldfd, newdirfd, ret;
 348     struct handle_data *data = (struct handle_data *)ctx->private;
 349
 350     oldfd = open_by_handle(data->mountfd, oldpath->data, O_PATH);
 351     if (oldfd < 0) {
 352         return oldfd;
 353     }
 354     newdirfd = open_by_handle(data->mountfd, dirpath->data, O_PATH);
 355     if (newdirfd < 0) {
 356         close(oldfd);
 357         return newdirfd;
 358     }
 359     ret = linkat(oldfd, "", newdirfd, name, AT_EMPTY_PATH);
 360     close(newdirfd);
 361     close(oldfd);
 362     return ret;
 363 }
 364
 365 static int handle_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size)
 366 {
 367     int fd, ret;
 368     struct handle_data *data = (struct handle_data *)ctx->private;
 369
 370     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK | O_WRONLY);
 371     if (fd < 0) {
 372         return fd;
 373     }
 374     ret = ftruncate(fd, size);
 375     close(fd);
 376     return ret;
 377 }
 378
 379 static int handle_rename(FsContext *ctx, const char *oldpath,
 380                          const char *newpath)
 381 {
 382     errno = EOPNOTSUPP;
 383     return -1;
 384 }
 385
 386 static int handle_chown(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
 387 {
 388     int fd, ret;
 389     struct handle_data *data = (struct handle_data *)fs_ctx->private;
 390
 391     fd = open_by_handle(data->mountfd, fs_path->data, O_PATH);
 392     if (fd < 0) {
 393         return fd;
 394     }
 395     ret = fchownat(fd, "", credp->fc_uid, credp->fc_gid, AT_EMPTY_PATH);
 396     close(fd);
 397     return ret;
 398 }
 399
 400 static int handle_utimensat(FsContext *ctx, V9fsPath *fs_path,
 401                             const struct timespec *buf)
 402 {
 403     int ret;
 404 #ifdef CONFIG_UTIMENSAT
 405     int fd;
 406     struct handle_data *data = (struct handle_data *)ctx->private;
 407
 408     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
 409     if (fd < 0) {
 410         return fd;
 411     }
 412     ret = futimens(fd, buf);
 413     close(fd);
 414 #else
 415     ret = -1;
 416     errno = ENOSYS;
 417 #endif
 418     return ret;
 419 }
 420
 421 static int handle_remove(FsContext *ctx, const char *path)
 422 {
 423     errno = EOPNOTSUPP;
 424     return -1;
 425 }
 426
 427 static int handle_fsync(FsContext *ctx, V9fsFidOpenState *fs, int datasync)
 428 {
 429     if (datasync) {
 430         return qemu_fdatasync(fs->fd);
 431     } else {
 432         return fsync(fs->fd);
 433     }
 434 }
 435
 436 static int handle_statfs(FsContext *ctx, V9fsPath *fs_path,
 437                          struct statfs *stbuf)
 438 {
 439     int fd, ret;
 440     struct handle_data *data = (struct handle_data *)ctx->private;
 441
 442     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
 443     if (fd < 0) {
 444         return fd;
 445     }
 446     ret = fstatfs(fd, stbuf);
 447     close(fd);
 448     return ret;
 449 }
 450
 451 static ssize_t handle_lgetxattr(FsContext *ctx, V9fsPath *fs_path,
 452                                 const char *name, void *value, size_t size)
 453 {
 454     int fd, ret;
 455     struct handle_data *data = (struct handle_data *)ctx->private;
 456
 457     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
 458     if (fd < 0) {
 459         return fd;
 460     }
 461     ret = fgetxattr(fd, name, value, size);
 462     close(fd);
 463     return ret;
 464 }
 465
 466 static ssize_t handle_llistxattr(FsContext *ctx, V9fsPath *fs_path,
 467                                  void *value, size_t size)
 468 {
 469     int fd, ret;
 470     struct handle_data *data = (struct handle_data *)ctx->private;
 471
 472     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
 473     if (fd < 0) {
 474         return fd;
 475     }
 476     ret = flistxattr(fd, value, size);
 477     close(fd);
 478     return ret;
 479 }
 480
 481 static int handle_lsetxattr(FsContext *ctx, V9fsPath *fs_path, const char *name,
 482                             void *value, size_t size, int flags)
 483 {
 484     int fd, ret;
 485     struct handle_data *data = (struct handle_data *)ctx->private;
 486
 487     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
 488     if (fd < 0) {
 489         return fd;
 490     }
 491     ret = fsetxattr(fd, name, value, size, flags);
 492     close(fd);
 493     return ret;
 494 }
 495
 496 static int handle_lremovexattr(FsContext *ctx, V9fsPath *fs_path,
 497                                const char *name)
 498 {
 499     int fd, ret;
 500     struct handle_data *data = (struct handle_data *)ctx->private;
 501
 502     fd = open_by_handle(data->mountfd, fs_path->data, O_NONBLOCK);
 503     if (fd < 0) {
 504         return fd;
 505     }
 506     ret = fremovexattr(fd, name);
 507     close(fd);
 508     return ret;
 509 }
 510
 511 static int handle_name_to_path(FsContext *ctx, V9fsPath *dir_path,
 512                               const char *name, V9fsPath *target)
 513 {
 514     char buffer[PATH_MAX];
 515     struct file_handle *fh;
 516     int dirfd, ret, mnt_id;
 517     struct handle_data *data = (struct handle_data *)ctx->private;
 518
 519     /* "." and ".." are not allowed */
 520     if (!strcmp(name, ".") || !strcmp(name, "..")) {
 521         errno = EINVAL;
 522         return -1;
 523
 524     }
 525     if (dir_path) {
 526         dirfd = open_by_handle(data->mountfd, dir_path->data, O_PATH);
 527     } else {
 528         /* relative to export root */
 529         dirfd = open(rpath(ctx, ".", buffer), O_DIRECTORY);
 530     }
 531     if (dirfd < 0) {
 532         return dirfd;
 533     }
 534     fh = g_malloc(sizeof(struct file_handle) + data->handle_bytes);
 535     fh->handle_bytes = data->handle_bytes;
 536     /* add a "./" at the begining of the path */
 537     snprintf(buffer, PATH_MAX, "./%s", name);
 538     /* flag = 0 imply don't follow symlink */
 539     ret = name_to_handle(dirfd, buffer, fh, &mnt_id, 0);
 540     if (!ret) {
 541         target->data = (char *)fh;
 542         target->size = sizeof(struct file_handle) + data->handle_bytes;
 543     } else {
 544         g_free(fh);
 545     }
 546     close(dirfd);
 547     return ret;
 548 }
 549
 550 static int handle_renameat(FsContext *ctx, V9fsPath *olddir,
 551                            const char *old_name, V9fsPath *newdir,
 552                            const char *new_name)
 553 {
 554     int olddirfd, newdirfd, ret;
 555     struct handle_data *data = (struct handle_data *)ctx->private;
 556
 557     olddirfd = open_by_handle(data->mountfd, olddir->data, O_PATH);
 558     if (olddirfd < 0) {
 559         return olddirfd;
 560     }
 561     newdirfd = open_by_handle(data->mountfd, newdir->data, O_PATH);
 562     if (newdirfd < 0) {
 563         close(olddirfd);
 564         return newdirfd;
 565     }
 566     ret = renameat(olddirfd, old_name, newdirfd, new_name);
 567     close(newdirfd);
 568     close(olddirfd);
 569     return ret;
 570 }
 571
 572 static int handle_unlinkat(FsContext *ctx, V9fsPath *dir,
 573                            const char *name, int flags)
 574 {
 575     int dirfd, ret;
 576     struct handle_data *data = (struct handle_data *)ctx->private;
 577
 578     dirfd = open_by_handle(data->mountfd, dir->data, O_PATH);
 579     if (dirfd < 0) {
 580         return dirfd;
 581     }
 582
 583     ret = unlinkat(dirfd, name, flags);
 584     close(dirfd);
 585     return ret;
 586 }
 587
 588 static int handle_ioc_getversion(FsContext *ctx, V9fsPath *path,
 589                                  mode_t st_mode, uint64_t *st_gen)
 590 {
 591     int err;
 592     V9fsFidOpenState fid_open;
 593
 594     /*
 595      * Do not try to open special files like device nodes, fifos etc
 596      * We can get fd for regular files and directories only
 597      */
 598     if (!S_ISREG(st_mode) && !S_ISDIR(st_mode)) {
 599             return 0;
 600     }
 601     err = handle_open(ctx, path, O_RDONLY, &fid_open);
 602     if (err < 0) {
 603         return err;
 604     }
 605     err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
 606     handle_close(ctx, &fid_open);
 607     return err;
 608 }
 609
 610 static int handle_init(FsContext *ctx)
 611 {
 612     int ret, mnt_id;
 613     struct statfs stbuf;
 614     struct file_handle fh;
 615     struct handle_data *data = g_malloc(sizeof(struct handle_data));
 616
 617     data->mountfd = open(ctx->fs_root, O_DIRECTORY);
 618     if (data->mountfd < 0) {
 619         ret = data->mountfd;
 620         goto err_out;
 621     }
 622     ret = statfs(ctx->fs_root, &stbuf);
 623     if (!ret) {
 624         switch (stbuf.f_type) {
 625         case EXT2_SUPER_MAGIC:
 626         case BTRFS_SUPER_MAGIC:
 627         case REISERFS_SUPER_MAGIC:
 628         case XFS_SUPER_MAGIC:
 629             ctx->exops.get_st_gen = handle_ioc_getversion;
 630             break;
 631         }
 632     }
 633     memset(&fh, 0, sizeof(struct file_handle));
 634     ret = name_to_handle(data->mountfd, ".", &fh, &mnt_id, 0);
 635     if (ret && errno == EOVERFLOW) {
 636         data->handle_bytes = fh.handle_bytes;
 637         ctx->private = data;
 638         ret = 0;
 639         goto out;
 640     }
 641     /* we got 0 byte handle ? */
 642     ret = -1;
 643     close(data->mountfd);
 644 err_out:
 645     g_free(data);
 646 out:
 647     return ret;
 648 }
 649
 650 FileOperations handle_ops = {
 651     .init         = handle_init,
 652     .lstat        = handle_lstat,
 653     .readlink     = handle_readlink,
 654     .close        = handle_close,
 655     .closedir     = handle_closedir,
 656     .open         = handle_open,
 657     .opendir      = handle_opendir,
 658     .rewinddir    = handle_rewinddir,
 659     .telldir      = handle_telldir,
 660     .readdir_r    = handle_readdir_r,
 661     .seekdir      = handle_seekdir,
 662     .preadv       = handle_preadv,
 663     .pwritev      = handle_pwritev,
 664     .chmod        = handle_chmod,
 665     .mknod        = handle_mknod,
 666     .mkdir        = handle_mkdir,
 667     .fstat        = handle_fstat,
 668     .open2        = handle_open2,
 669     .symlink      = handle_symlink,
 670     .link         = handle_link,
 671     .truncate     = handle_truncate,
 672     .rename       = handle_rename,
 673     .chown        = handle_chown,
 674     .utimensat    = handle_utimensat,
 675     .remove       = handle_remove,
 676     .fsync        = handle_fsync,
 677     .statfs       = handle_statfs,
 678     .lgetxattr    = handle_lgetxattr,
 679     .llistxattr   = handle_llistxattr,
 680     .lsetxattr    = handle_lsetxattr,
 681     .lremovexattr = handle_lremovexattr,
 682     .name_to_path = handle_name_to_path,
 683     .renameat     = handle_renameat,
 684     .unlinkat     = handle_unlinkat,
 685 };