hw/9pfs/9p-local.c

   1 /*
   2  * 9p Posix callback
   3  *
   4  * Copyright IBM, Corp. 2010
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.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  * Not so fast! You might want to read the 9p developer docs first:
  15  * https://wiki.qemu.org/Documentation/9p
  16  */
  17
  18 #include "qemu/osdep.h"
  19 #include "9p.h"
  20 #include "9p-local.h"
  21 #include "9p-xattr.h"
  22 #include "9p-util.h"
  23 #include "fsdev/qemu-fsdev.h"   /* local_ops */
  24 #include <arpa/inet.h>
  25 #include <pwd.h>
  26 #include <grp.h>
  27 #include <sys/socket.h>
  28 #include <sys/un.h>
  29 #include "qemu/xattr.h"
  30 #include "qapi/error.h"
  31 #include "qemu/cutils.h"
  32 #include "qemu/error-report.h"
  33 #include "qemu/option.h"
  34 #include <libgen.h>
  35 #include <linux/fs.h>
  36 #ifdef CONFIG_LINUX_MAGIC_H
  37 #include <linux/magic.h>
  38 #endif
  39 #include <sys/ioctl.h>
  40
  41 #ifndef XFS_SUPER_MAGIC
  42 #define XFS_SUPER_MAGIC  0x58465342
  43 #endif
  44 #ifndef EXT2_SUPER_MAGIC
  45 #define EXT2_SUPER_MAGIC 0xEF53
  46 #endif
  47 #ifndef REISERFS_SUPER_MAGIC
  48 #define REISERFS_SUPER_MAGIC 0x52654973
  49 #endif
  50 #ifndef BTRFS_SUPER_MAGIC
  51 #define BTRFS_SUPER_MAGIC 0x9123683E
  52 #endif
  53
  54 typedef struct {
  55     int mountfd;
  56 } LocalData;
  57
  58 int local_open_nofollow(FsContext *fs_ctx, const char *path, int flags,
  59                         mode_t mode)
  60 {
  61     LocalData *data = fs_ctx->private;
  62     int fd = data->mountfd;
  63
  64     while (*path && fd != -1) {
  65         const char *c;
  66         int next_fd;
  67         char *head;
  68
  69         /* Only relative paths without consecutive slashes */
  70         assert(*path != '/');
  71
  72         head = g_strdup(path);
  73         c = qemu_strchrnul(path, '/');
  74         if (*c) {
  75             /* Intermediate path element */
  76             head[c - path] = 0;
  77             path = c + 1;
  78             next_fd = openat_dir(fd, head);
  79         } else {
  80             /* Rightmost path element */
  81             next_fd = openat_file(fd, head, flags, mode);
  82             path = c;
  83         }
  84         g_free(head);
  85         if (fd != data->mountfd) {
  86             close_preserve_errno(fd);
  87         }
  88         fd = next_fd;
  89     }
  90
  91     assert(fd != data->mountfd);
  92     return fd;
  93 }
  94
  95 int local_opendir_nofollow(FsContext *fs_ctx, const char *path)
  96 {
  97     return local_open_nofollow(fs_ctx, path, O_DIRECTORY | O_RDONLY, 0);
  98 }
  99
 100 static void renameat_preserve_errno(int odirfd, const char *opath, int ndirfd,
 101                                     const char *npath)
 102 {
 103     int serrno = errno;
 104     renameat(odirfd, opath, ndirfd, npath);
 105     errno = serrno;
 106 }
 107
 108 static void unlinkat_preserve_errno(int dirfd, const char *path, int flags)
 109 {
 110     int serrno = errno;
 111     unlinkat(dirfd, path, flags);
 112     errno = serrno;
 113 }
 114
 115 #define VIRTFS_META_DIR ".virtfs_metadata"
 116 #define VIRTFS_META_ROOT_FILE VIRTFS_META_DIR "_root"
 117
 118 static FILE *local_fopenat(int dirfd, const char *name, const char *mode)
 119 {
 120     int fd, o_mode = 0;
 121     FILE *fp;
 122     int flags;
 123     /*
 124      * only supports two modes
 125      */
 126     if (mode[0] == 'r') {
 127         flags = O_RDONLY;
 128     } else if (mode[0] == 'w') {
 129         flags = O_WRONLY | O_TRUNC | O_CREAT;
 130         o_mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
 131     } else {
 132         return NULL;
 133     }
 134     fd = openat_file(dirfd, name, flags, o_mode);
 135     if (fd == -1) {
 136         return NULL;
 137     }
 138     fp = fdopen(fd, mode);
 139     if (!fp) {
 140         close(fd);
 141     }
 142     return fp;
 143 }
 144
 145 #define ATTR_MAX 100
 146 static void local_mapped_file_attr(int dirfd, const char *name,
 147                                    struct stat *stbuf)
 148 {
 149     FILE *fp;
 150     char buf[ATTR_MAX];
 151     int map_dirfd;
 152
 153     if (strcmp(name, ".")) {
 154         map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
 155         if (map_dirfd == -1) {
 156             return;
 157         }
 158
 159         fp = local_fopenat(map_dirfd, name, "r");
 160         close_preserve_errno(map_dirfd);
 161     } else {
 162         fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "r");
 163     }
 164     if (!fp) {
 165         return;
 166     }
 167     memset(buf, 0, ATTR_MAX);
 168     while (fgets(buf, ATTR_MAX, fp)) {
 169         if (!strncmp(buf, "virtfs.uid", 10)) {
 170             stbuf->st_uid = atoi(buf + 11);
 171         } else if (!strncmp(buf, "virtfs.gid", 10)) {
 172             stbuf->st_gid = atoi(buf + 11);
 173         } else if (!strncmp(buf, "virtfs.mode", 11)) {
 174             stbuf->st_mode = atoi(buf + 12);
 175         } else if (!strncmp(buf, "virtfs.rdev", 11)) {
 176             stbuf->st_rdev = atoi(buf + 12);
 177         }
 178         memset(buf, 0, ATTR_MAX);
 179     }
 180     fclose(fp);
 181 }
 182
 183 static int local_lstat(FsContext *fs_ctx, V9fsPath *fs_path, struct stat *stbuf)
 184 {
 185     int err = -1;
 186     char *dirpath = g_path_get_dirname(fs_path->data);
 187     char *name = g_path_get_basename(fs_path->data);
 188     int dirfd;
 189
 190     dirfd = local_opendir_nofollow(fs_ctx, dirpath);
 191     if (dirfd == -1) {
 192         goto out;
 193     }
 194
 195     err = fstatat(dirfd, name, stbuf, AT_SYMLINK_NOFOLLOW);
 196     if (err) {
 197         goto err_out;
 198     }
 199     if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 200         /* Actual credentials are part of extended attrs */
 201         uid_t tmp_uid;
 202         gid_t tmp_gid;
 203         mode_t tmp_mode;
 204         dev_t tmp_dev;
 205
 206         if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.uid", &tmp_uid,
 207                                  sizeof(uid_t)) > 0) {
 208             stbuf->st_uid = le32_to_cpu(tmp_uid);
 209         }
 210         if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.gid", &tmp_gid,
 211                                  sizeof(gid_t)) > 0) {
 212             stbuf->st_gid = le32_to_cpu(tmp_gid);
 213         }
 214         if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.mode", &tmp_mode,
 215                                  sizeof(mode_t)) > 0) {
 216             stbuf->st_mode = le32_to_cpu(tmp_mode);
 217         }
 218         if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.rdev", &tmp_dev,
 219                                  sizeof(dev_t)) > 0) {
 220             stbuf->st_rdev = le64_to_cpu(tmp_dev);
 221         }
 222     } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 223         local_mapped_file_attr(dirfd, name, stbuf);
 224     }
 225
 226 err_out:
 227     close_preserve_errno(dirfd);
 228 out:
 229     g_free(name);
 230     g_free(dirpath);
 231     return err;
 232 }
 233
 234 static int local_set_mapped_file_attrat(int dirfd, const char *name,
 235                                         FsCred *credp)
 236 {
 237     FILE *fp;
 238     int ret;
 239     char buf[ATTR_MAX];
 240     int uid = -1, gid = -1, mode = -1, rdev = -1;
 241     int map_dirfd = -1, map_fd;
 242     bool is_root = !strcmp(name, ".");
 243
 244     if (is_root) {
 245         fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "r");
 246         if (!fp) {
 247             if (errno == ENOENT) {
 248                 goto update_map_file;
 249             } else {
 250                 return -1;
 251             }
 252         }
 253     } else {
 254         ret = mkdirat(dirfd, VIRTFS_META_DIR, 0700);
 255         if (ret < 0 && errno != EEXIST) {
 256             return -1;
 257         }
 258
 259         map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
 260         if (map_dirfd == -1) {
 261             return -1;
 262         }
 263
 264         fp = local_fopenat(map_dirfd, name, "r");
 265         if (!fp) {
 266             if (errno == ENOENT) {
 267                 goto update_map_file;
 268             } else {
 269                 close_preserve_errno(map_dirfd);
 270                 return -1;
 271             }
 272         }
 273     }
 274     memset(buf, 0, ATTR_MAX);
 275     while (fgets(buf, ATTR_MAX, fp)) {
 276         if (!strncmp(buf, "virtfs.uid", 10)) {
 277             uid = atoi(buf + 11);
 278         } else if (!strncmp(buf, "virtfs.gid", 10)) {
 279             gid = atoi(buf + 11);
 280         } else if (!strncmp(buf, "virtfs.mode", 11)) {
 281             mode = atoi(buf + 12);
 282         } else if (!strncmp(buf, "virtfs.rdev", 11)) {
 283             rdev = atoi(buf + 12);
 284         }
 285         memset(buf, 0, ATTR_MAX);
 286     }
 287     fclose(fp);
 288
 289 update_map_file:
 290     if (is_root) {
 291         fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "w");
 292     } else {
 293         fp = local_fopenat(map_dirfd, name, "w");
 294         /* We can't go this far with map_dirfd not being a valid file descriptor
 295          * but some versions of gcc aren't smart enough to see it.
 296          */
 297         if (map_dirfd != -1) {
 298             close_preserve_errno(map_dirfd);
 299         }
 300     }
 301     if (!fp) {
 302         return -1;
 303     }
 304
 305     map_fd = fileno(fp);
 306     assert(map_fd != -1);
 307     ret = fchmod(map_fd, 0600);
 308     assert(ret == 0);
 309
 310     if (credp->fc_uid != -1) {
 311         uid = credp->fc_uid;
 312     }
 313     if (credp->fc_gid != -1) {
 314         gid = credp->fc_gid;
 315     }
 316     if (credp->fc_mode != (mode_t)-1) {
 317         mode = credp->fc_mode;
 318     }
 319     if (credp->fc_rdev != -1) {
 320         rdev = credp->fc_rdev;
 321     }
 322
 323     if (uid != -1) {
 324         fprintf(fp, "virtfs.uid=%d\n", uid);
 325     }
 326     if (gid != -1) {
 327         fprintf(fp, "virtfs.gid=%d\n", gid);
 328     }
 329     if (mode != -1) {
 330         fprintf(fp, "virtfs.mode=%d\n", mode);
 331     }
 332     if (rdev != -1) {
 333         fprintf(fp, "virtfs.rdev=%d\n", rdev);
 334     }
 335     fclose(fp);
 336
 337     return 0;
 338 }
 339
 340 static int fchmodat_nofollow(int dirfd, const char *name, mode_t mode)
 341 {
 342     struct stat stbuf;
 343     int fd, ret;
 344
 345     /* FIXME: this should be handled with fchmodat(AT_SYMLINK_NOFOLLOW).
 346      * Unfortunately, the linux kernel doesn't implement it yet.
 347      */
 348
 349      /* First, we clear non-racing symlinks out of the way. */
 350     if (fstatat(dirfd, name, &stbuf, AT_SYMLINK_NOFOLLOW)) {
 351         return -1;
 352     }
 353     if (S_ISLNK(stbuf.st_mode)) {
 354         errno = ELOOP;
 355         return -1;
 356     }
 357
 358     fd = openat_file(dirfd, name, O_RDONLY | O_PATH_9P_UTIL | O_NOFOLLOW, 0);
 359 #if O_PATH_9P_UTIL == 0
 360     /* Fallback for systems that don't support O_PATH: we depend on the file
 361      * being readable or writable.
 362      */
 363     if (fd == -1) {
 364         /* In case the file is writable-only and isn't a directory. */
 365         if (errno == EACCES) {
 366             fd = openat_file(dirfd, name, O_WRONLY, 0);
 367         }
 368         if (fd == -1 && errno == EISDIR) {
 369             errno = EACCES;
 370         }
 371     }
 372     if (fd == -1) {
 373         return -1;
 374     }
 375     ret = fchmod(fd, mode);
 376 #else
 377     /* Access modes are ignored when O_PATH is supported. If name is a symbolic
 378      * link, O_PATH | O_NOFOLLOW causes openat(2) to return a file descriptor
 379      * referring to the symbolic link.
 380      */
 381     if (fd == -1) {
 382         return -1;
 383     }
 384
 385     /* Now we handle racing symlinks. */
 386     ret = fstat(fd, &stbuf);
 387     if (!ret) {
 388         if (S_ISLNK(stbuf.st_mode)) {
 389             errno = ELOOP;
 390             ret = -1;
 391         } else {
 392             char *proc_path = g_strdup_printf("/proc/self/fd/%d", fd);
 393             ret = chmod(proc_path, mode);
 394             g_free(proc_path);
 395         }
 396     }
 397 #endif
 398     close_preserve_errno(fd);
 399     return ret;
 400 }
 401
 402 static int local_set_xattrat(int dirfd, const char *path, FsCred *credp)
 403 {
 404     int err;
 405
 406     if (credp->fc_uid != -1) {
 407         uint32_t tmp_uid = cpu_to_le32(credp->fc_uid);
 408         err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.uid", &tmp_uid,
 409                                    sizeof(uid_t), 0);
 410         if (err) {
 411             return err;
 412         }
 413     }
 414     if (credp->fc_gid != -1) {
 415         uint32_t tmp_gid = cpu_to_le32(credp->fc_gid);
 416         err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.gid", &tmp_gid,
 417                                    sizeof(gid_t), 0);
 418         if (err) {
 419             return err;
 420         }
 421     }
 422     if (credp->fc_mode != (mode_t)-1) {
 423         uint32_t tmp_mode = cpu_to_le32(credp->fc_mode);
 424         err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.mode", &tmp_mode,
 425                                    sizeof(mode_t), 0);
 426         if (err) {
 427             return err;
 428         }
 429     }
 430     if (credp->fc_rdev != -1) {
 431         uint64_t tmp_rdev = cpu_to_le64(credp->fc_rdev);
 432         err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.rdev", &tmp_rdev,
 433                                    sizeof(dev_t), 0);
 434         if (err) {
 435             return err;
 436         }
 437     }
 438     return 0;
 439 }
 440
 441 static int local_set_cred_passthrough(FsContext *fs_ctx, int dirfd,
 442                                       const char *name, FsCred *credp)
 443 {
 444     if (fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
 445                  AT_SYMLINK_NOFOLLOW) < 0) {
 446         /*
 447          * If we fail to change ownership and if we are
 448          * using security model none. Ignore the error
 449          */
 450         if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
 451             return -1;
 452         }
 453     }
 454
 455     return fchmodat_nofollow(dirfd, name, credp->fc_mode & 07777);
 456 }
 457
 458 static ssize_t local_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
 459                               char *buf, size_t bufsz)
 460 {
 461     ssize_t tsize = -1;
 462
 463     if ((fs_ctx->export_flags & V9FS_SM_MAPPED) ||
 464         (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE)) {
 465         int fd;
 466
 467         fd = local_open_nofollow(fs_ctx, fs_path->data, O_RDONLY, 0);
 468         if (fd == -1) {
 469             return -1;
 470         }
 471         do {
 472             tsize = read(fd, (void *)buf, bufsz);
 473         } while (tsize == -1 && errno == EINTR);
 474         close_preserve_errno(fd);
 475     } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
 476                (fs_ctx->export_flags & V9FS_SM_NONE)) {
 477         char *dirpath = g_path_get_dirname(fs_path->data);
 478         char *name = g_path_get_basename(fs_path->data);
 479         int dirfd;
 480
 481         dirfd = local_opendir_nofollow(fs_ctx, dirpath);
 482         if (dirfd == -1) {
 483             goto out;
 484         }
 485
 486         tsize = readlinkat(dirfd, name, buf, bufsz);
 487         close_preserve_errno(dirfd);
 488     out:
 489         g_free(name);
 490         g_free(dirpath);
 491     }
 492     return tsize;
 493 }
 494
 495 static int local_close(FsContext *ctx, V9fsFidOpenState *fs)
 496 {
 497     return close(fs->fd);
 498 }
 499
 500 static int local_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 501 {
 502     return closedir(fs->dir.stream);
 503 }
 504
 505 static int local_open(FsContext *ctx, V9fsPath *fs_path,
 506                       int flags, V9fsFidOpenState *fs)
 507 {
 508     int fd;
 509
 510     fd = local_open_nofollow(ctx, fs_path->data, flags, 0);
 511     if (fd == -1) {
 512         return -1;
 513     }
 514     fs->fd = fd;
 515     return fs->fd;
 516 }
 517
 518 static int local_opendir(FsContext *ctx,
 519                          V9fsPath *fs_path, V9fsFidOpenState *fs)
 520 {
 521     int dirfd;
 522     DIR *stream;
 523
 524     dirfd = local_opendir_nofollow(ctx, fs_path->data);
 525     if (dirfd == -1) {
 526         return -1;
 527     }
 528
 529     stream = fdopendir(dirfd);
 530     if (!stream) {
 531         close(dirfd);
 532         return -1;
 533     }
 534     fs->dir.stream = stream;
 535     return 0;
 536 }
 537
 538 static void local_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 539 {
 540     rewinddir(fs->dir.stream);
 541 }
 542
 543 static off_t local_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 544 {
 545     return telldir(fs->dir.stream);
 546 }
 547
 548 static bool local_is_mapped_file_metadata(FsContext *fs_ctx, const char *name)
 549 {
 550     return
 551         !strcmp(name, VIRTFS_META_DIR) || !strcmp(name, VIRTFS_META_ROOT_FILE);
 552 }
 553
 554 static struct dirent *local_readdir(FsContext *ctx, V9fsFidOpenState *fs)
 555 {
 556     struct dirent *entry;
 557
 558 again:
 559     entry = readdir(fs->dir.stream);
 560     if (!entry) {
 561         return NULL;
 562     }
 563
 564     if (ctx->export_flags & V9FS_SM_MAPPED) {
 565         entry->d_type = DT_UNKNOWN;
 566     } else if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 567         if (local_is_mapped_file_metadata(ctx, entry->d_name)) {
 568             /* skip the meta data */
 569             goto again;
 570         }
 571         entry->d_type = DT_UNKNOWN;
 572     }
 573
 574     return entry;
 575 }
 576
 577 static void local_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 578 {
 579     seekdir(fs->dir.stream, off);
 580 }
 581
 582 static ssize_t local_preadv(FsContext *ctx, V9fsFidOpenState *fs,
 583                             const struct iovec *iov,
 584                             int iovcnt, off_t offset)
 585 {
 586 #ifdef CONFIG_PREADV
 587     return preadv(fs->fd, iov, iovcnt, offset);
 588 #else
 589     int err = lseek(fs->fd, offset, SEEK_SET);
 590     if (err == -1) {
 591         return err;
 592     } else {
 593         return readv(fs->fd, iov, iovcnt);
 594     }
 595 #endif
 596 }
 597
 598 static ssize_t local_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
 599                              const struct iovec *iov,
 600                              int iovcnt, off_t offset)
 601 {
 602     ssize_t ret;
 603 #ifdef CONFIG_PREADV
 604     ret = pwritev(fs->fd, iov, iovcnt, offset);
 605 #else
 606     int err = lseek(fs->fd, offset, SEEK_SET);
 607     if (err == -1) {
 608         return err;
 609     } else {
 610         ret = writev(fs->fd, iov, iovcnt);
 611     }
 612 #endif
 613 #ifdef CONFIG_SYNC_FILE_RANGE
 614     if (ret > 0 && ctx->export_flags & V9FS_IMMEDIATE_WRITEOUT) {
 615         /*
 616          * Initiate a writeback. This is not a data integrity sync.
 617          * We want to ensure that we don't leave dirty pages in the cache
 618          * after write when writeout=immediate is sepcified.
 619          */
 620         sync_file_range(fs->fd, offset, ret,
 621                         SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE);
 622     }
 623 #endif
 624     return ret;
 625 }
 626
 627 static int local_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
 628 {
 629     char *dirpath = g_path_get_dirname(fs_path->data);
 630     char *name = g_path_get_basename(fs_path->data);
 631     int ret = -1;
 632     int dirfd;
 633
 634     dirfd = local_opendir_nofollow(fs_ctx, dirpath);
 635     if (dirfd == -1) {
 636         goto out;
 637     }
 638
 639     if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 640         ret = local_set_xattrat(dirfd, name, credp);
 641     } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 642         ret = local_set_mapped_file_attrat(dirfd, name, credp);
 643     } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 644                fs_ctx->export_flags & V9FS_SM_NONE) {
 645         ret = fchmodat_nofollow(dirfd, name, credp->fc_mode);
 646     }
 647     close_preserve_errno(dirfd);
 648
 649 out:
 650     g_free(dirpath);
 651     g_free(name);
 652     return ret;
 653 }
 654
 655 static int local_mknod(FsContext *fs_ctx, V9fsPath *dir_path,
 656                        const char *name, FsCred *credp)
 657 {
 658     int err = -1;
 659     int dirfd;
 660
 661     if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 662         local_is_mapped_file_metadata(fs_ctx, name)) {
 663         errno = EINVAL;
 664         return -1;
 665     }
 666
 667     dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 668     if (dirfd == -1) {
 669         return -1;
 670     }
 671
 672     if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 673         fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 674         err = mknodat(dirfd, name, fs_ctx->fmode | S_IFREG, 0);
 675         if (err == -1) {
 676             goto out;
 677         }
 678
 679         if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 680             err = local_set_xattrat(dirfd, name, credp);
 681         } else {
 682             err = local_set_mapped_file_attrat(dirfd, name, credp);
 683         }
 684         if (err == -1) {
 685             goto err_end;
 686         }
 687     } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 688                fs_ctx->export_flags & V9FS_SM_NONE) {
 689         err = mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev);
 690         if (err == -1) {
 691             goto out;
 692         }
 693         err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
 694         if (err == -1) {
 695             goto err_end;
 696         }
 697     }
 698     goto out;
 699
 700 err_end:
 701     unlinkat_preserve_errno(dirfd, name, 0);
 702 out:
 703     close_preserve_errno(dirfd);
 704     return err;
 705 }
 706
 707 static int local_mkdir(FsContext *fs_ctx, V9fsPath *dir_path,
 708                        const char *name, FsCred *credp)
 709 {
 710     int err = -1;
 711     int dirfd;
 712
 713     if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 714         local_is_mapped_file_metadata(fs_ctx, name)) {
 715         errno = EINVAL;
 716         return -1;
 717     }
 718
 719     dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 720     if (dirfd == -1) {
 721         return -1;
 722     }
 723
 724     if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 725         fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 726         err = mkdirat(dirfd, name, fs_ctx->dmode);
 727         if (err == -1) {
 728             goto out;
 729         }
 730         credp->fc_mode = credp->fc_mode | S_IFDIR;
 731
 732         if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 733             err = local_set_xattrat(dirfd, name, credp);
 734         } else {
 735             err = local_set_mapped_file_attrat(dirfd, name, credp);
 736         }
 737         if (err == -1) {
 738             goto err_end;
 739         }
 740     } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 741                fs_ctx->export_flags & V9FS_SM_NONE) {
 742         err = mkdirat(dirfd, name, credp->fc_mode);
 743         if (err == -1) {
 744             goto out;
 745         }
 746         err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
 747         if (err == -1) {
 748             goto err_end;
 749         }
 750     }
 751     goto out;
 752
 753 err_end:
 754     unlinkat_preserve_errno(dirfd, name, AT_REMOVEDIR);
 755 out:
 756     close_preserve_errno(dirfd);
 757     return err;
 758 }
 759
 760 static int local_fstat(FsContext *fs_ctx, int fid_type,
 761                        V9fsFidOpenState *fs, struct stat *stbuf)
 762 {
 763     int err, fd;
 764
 765     if (fid_type == P9_FID_DIR) {
 766         fd = dirfd(fs->dir.stream);
 767     } else {
 768         fd = fs->fd;
 769     }
 770
 771     err = fstat(fd, stbuf);
 772     if (err) {
 773         return err;
 774     }
 775     if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 776         /* Actual credentials are part of extended attrs */
 777         uid_t tmp_uid;
 778         gid_t tmp_gid;
 779         mode_t tmp_mode;
 780         dev_t tmp_dev;
 781
 782         if (fgetxattr(fd, "user.virtfs.uid", &tmp_uid, sizeof(uid_t)) > 0) {
 783             stbuf->st_uid = le32_to_cpu(tmp_uid);
 784         }
 785         if (fgetxattr(fd, "user.virtfs.gid", &tmp_gid, sizeof(gid_t)) > 0) {
 786             stbuf->st_gid = le32_to_cpu(tmp_gid);
 787         }
 788         if (fgetxattr(fd, "user.virtfs.mode", &tmp_mode, sizeof(mode_t)) > 0) {
 789             stbuf->st_mode = le32_to_cpu(tmp_mode);
 790         }
 791         if (fgetxattr(fd, "user.virtfs.rdev", &tmp_dev, sizeof(dev_t)) > 0) {
 792             stbuf->st_rdev = le64_to_cpu(tmp_dev);
 793         }
 794     } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 795         errno = EOPNOTSUPP;
 796         return -1;
 797     }
 798     return err;
 799 }
 800
 801 static int local_open2(FsContext *fs_ctx, V9fsPath *dir_path, const char *name,
 802                        int flags, FsCred *credp, V9fsFidOpenState *fs)
 803 {
 804     int fd = -1;
 805     int err = -1;
 806     int dirfd;
 807
 808     if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 809         local_is_mapped_file_metadata(fs_ctx, name)) {
 810         errno = EINVAL;
 811         return -1;
 812     }
 813
 814     /*
 815      * Mark all the open to not follow symlinks
 816      */
 817     flags |= O_NOFOLLOW;
 818
 819     dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 820     if (dirfd == -1) {
 821         return -1;
 822     }
 823
 824     /* Determine the security model */
 825     if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 826         fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 827         fd = openat_file(dirfd, name, flags, fs_ctx->fmode);
 828         if (fd == -1) {
 829             goto out;
 830         }
 831         credp->fc_mode = credp->fc_mode | S_IFREG;
 832         if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 833             /* Set cleint credentials in xattr */
 834             err = local_set_xattrat(dirfd, name, credp);
 835         } else {
 836             err = local_set_mapped_file_attrat(dirfd, name, credp);
 837         }
 838         if (err == -1) {
 839             goto err_end;
 840         }
 841     } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
 842                (fs_ctx->export_flags & V9FS_SM_NONE)) {
 843         fd = openat_file(dirfd, name, flags, credp->fc_mode);
 844         if (fd == -1) {
 845             goto out;
 846         }
 847         err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
 848         if (err == -1) {
 849             goto err_end;
 850         }
 851     }
 852     err = fd;
 853     fs->fd = fd;
 854     goto out;
 855
 856 err_end:
 857     unlinkat_preserve_errno(dirfd, name,
 858                             flags & O_DIRECTORY ? AT_REMOVEDIR : 0);
 859     close_preserve_errno(fd);
 860 out:
 861     close_preserve_errno(dirfd);
 862     return err;
 863 }
 864
 865
 866 static int local_symlink(FsContext *fs_ctx, const char *oldpath,
 867                          V9fsPath *dir_path, const char *name, FsCred *credp)
 868 {
 869     int err = -1;
 870     int dirfd;
 871
 872     if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 873         local_is_mapped_file_metadata(fs_ctx, name)) {
 874         errno = EINVAL;
 875         return -1;
 876     }
 877
 878     dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 879     if (dirfd == -1) {
 880         return -1;
 881     }
 882
 883     /* Determine the security model */
 884     if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 885         fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 886         int fd;
 887         ssize_t oldpath_size, write_size;
 888
 889         fd = openat_file(dirfd, name, O_CREAT | O_EXCL | O_RDWR,
 890                          fs_ctx->fmode);
 891         if (fd == -1) {
 892             goto out;
 893         }
 894         /* Write the oldpath (target) to the file. */
 895         oldpath_size = strlen(oldpath);
 896         do {
 897             write_size = write(fd, (void *)oldpath, oldpath_size);
 898         } while (write_size == -1 && errno == EINTR);
 899         close_preserve_errno(fd);
 900
 901         if (write_size != oldpath_size) {
 902             goto err_end;
 903         }
 904         /* Set cleint credentials in symlink's xattr */
 905         credp->fc_mode = credp->fc_mode | S_IFLNK;
 906
 907         if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 908             err = local_set_xattrat(dirfd, name, credp);
 909         } else {
 910             err = local_set_mapped_file_attrat(dirfd, name, credp);
 911         }
 912         if (err == -1) {
 913             goto err_end;
 914         }
 915     } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 916                fs_ctx->export_flags & V9FS_SM_NONE) {
 917         err = symlinkat(oldpath, dirfd, name);
 918         if (err) {
 919             goto out;
 920         }
 921         err = fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
 922                        AT_SYMLINK_NOFOLLOW);
 923         if (err == -1) {
 924             /*
 925              * If we fail to change ownership and if we are
 926              * using security model none. Ignore the error
 927              */
 928             if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
 929                 goto err_end;
 930             } else {
 931                 err = 0;
 932             }
 933         }
 934     }
 935     goto out;
 936
 937 err_end:
 938     unlinkat_preserve_errno(dirfd, name, 0);
 939 out:
 940     close_preserve_errno(dirfd);
 941     return err;
 942 }
 943
 944 static int local_link(FsContext *ctx, V9fsPath *oldpath,
 945                       V9fsPath *dirpath, const char *name)
 946 {
 947     char *odirpath = g_path_get_dirname(oldpath->data);
 948     char *oname = g_path_get_basename(oldpath->data);
 949     int ret = -1;
 950     int odirfd, ndirfd;
 951
 952     if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 953         local_is_mapped_file_metadata(ctx, name)) {
 954         errno = EINVAL;
 955         goto out;
 956     }
 957
 958     odirfd = local_opendir_nofollow(ctx, odirpath);
 959     if (odirfd == -1) {
 960         goto out;
 961     }
 962
 963     ndirfd = local_opendir_nofollow(ctx, dirpath->data);
 964     if (ndirfd == -1) {
 965         close_preserve_errno(odirfd);
 966         goto out;
 967     }
 968
 969     ret = linkat(odirfd, oname, ndirfd, name, 0);
 970     if (ret < 0) {
 971         goto out_close;
 972     }
 973
 974     /* now link the virtfs_metadata files */
 975     if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 976         int omap_dirfd, nmap_dirfd;
 977
 978         ret = mkdirat(ndirfd, VIRTFS_META_DIR, 0700);
 979         if (ret < 0 && errno != EEXIST) {
 980             goto err_undo_link;
 981         }
 982
 983         omap_dirfd = openat_dir(odirfd, VIRTFS_META_DIR);
 984         if (omap_dirfd == -1) {
 985             goto err;
 986         }
 987
 988         nmap_dirfd = openat_dir(ndirfd, VIRTFS_META_DIR);
 989         if (nmap_dirfd == -1) {
 990             close_preserve_errno(omap_dirfd);
 991             goto err;
 992         }
 993
 994         ret = linkat(omap_dirfd, oname, nmap_dirfd, name, 0);
 995         close_preserve_errno(nmap_dirfd);
 996         close_preserve_errno(omap_dirfd);
 997         if (ret < 0 && errno != ENOENT) {
 998             goto err_undo_link;
 999         }
1000
1001         ret = 0;
1002     }
1003     goto out_close;
1004
1005 err:
1006     ret = -1;
1007 err_undo_link:
1008     unlinkat_preserve_errno(ndirfd, name, 0);
1009 out_close:
1010     close_preserve_errno(ndirfd);
1011     close_preserve_errno(odirfd);
1012 out:
1013     g_free(oname);
1014     g_free(odirpath);
1015     return ret;
1016 }
1017
1018 static int local_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size)
1019 {
1020     int fd, ret;
1021
1022     fd = local_open_nofollow(ctx, fs_path->data, O_WRONLY, 0);
1023     if (fd == -1) {
1024         return -1;
1025     }
1026     ret = ftruncate(fd, size);
1027     close_preserve_errno(fd);
1028     return ret;
1029 }
1030
1031 static int local_chown(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
1032 {
1033     char *dirpath = g_path_get_dirname(fs_path->data);
1034     char *name = g_path_get_basename(fs_path->data);
1035     int ret = -1;
1036     int dirfd;
1037
1038     dirfd = local_opendir_nofollow(fs_ctx, dirpath);
1039     if (dirfd == -1) {
1040         goto out;
1041     }
1042
1043     if ((credp->fc_uid == -1 && credp->fc_gid == -1) ||
1044         (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
1045         (fs_ctx->export_flags & V9FS_SM_NONE)) {
1046         ret = fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
1047                        AT_SYMLINK_NOFOLLOW);
1048     } else if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
1049         ret = local_set_xattrat(dirfd, name, credp);
1050     } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1051         ret = local_set_mapped_file_attrat(dirfd, name, credp);
1052     }
1053
1054     close_preserve_errno(dirfd);
1055 out:
1056     g_free(name);
1057     g_free(dirpath);
1058     return ret;
1059 }
1060
1061 static int local_utimensat(FsContext *s, V9fsPath *fs_path,
1062                            const struct timespec *buf)
1063 {
1064     char *dirpath = g_path_get_dirname(fs_path->data);
1065     char *name = g_path_get_basename(fs_path->data);
1066     int dirfd, ret = -1;
1067
1068     dirfd = local_opendir_nofollow(s, dirpath);
1069     if (dirfd == -1) {
1070         goto out;
1071     }
1072
1073     ret = utimensat(dirfd, name, buf, AT_SYMLINK_NOFOLLOW);
1074     close_preserve_errno(dirfd);
1075 out:
1076     g_free(dirpath);
1077     g_free(name);
1078     return ret;
1079 }
1080
1081 static int local_unlinkat_common(FsContext *ctx, int dirfd, const char *name,
1082                                  int flags)
1083 {
1084     int ret;
1085
1086     if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1087         int map_dirfd;
1088
1089         /* We need to remove the metadata as well:
1090          * - the metadata directory if we're removing a directory
1091          * - the metadata file in the parent's metadata directory
1092          *
1093          * If any of these are missing (ie, ENOENT) then we're probably
1094          * trying to remove something that wasn't created in mapped-file
1095          * mode. We just ignore the error.
1096          */
1097         if (flags == AT_REMOVEDIR) {
1098             int fd;
1099
1100             fd = openat_dir(dirfd, name);
1101             if (fd == -1) {
1102                 return -1;
1103             }
1104             ret = unlinkat(fd, VIRTFS_META_DIR, AT_REMOVEDIR);
1105             close_preserve_errno(fd);
1106             if (ret < 0 && errno != ENOENT) {
1107                 return -1;
1108             }
1109         }
1110         map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
1111         if (map_dirfd != -1) {
1112             ret = unlinkat(map_dirfd, name, 0);
1113             close_preserve_errno(map_dirfd);
1114             if (ret < 0 && errno != ENOENT) {
1115                 return -1;
1116             }
1117         } else if (errno != ENOENT) {
1118             return -1;
1119         }
1120     }
1121
1122     return unlinkat(dirfd, name, flags);
1123 }
1124
1125 static int local_remove(FsContext *ctx, const char *path)
1126 {
1127     struct stat stbuf;
1128     char *dirpath = g_path_get_dirname(path);
1129     char *name = g_path_get_basename(path);
1130     int flags = 0;
1131     int dirfd;
1132     int err = -1;
1133
1134     dirfd = local_opendir_nofollow(ctx, dirpath);
1135     if (dirfd == -1) {
1136         goto out;
1137     }
1138
1139     if (fstatat(dirfd, name, &stbuf, AT_SYMLINK_NOFOLLOW) < 0) {
1140         goto err_out;
1141     }
1142
1143     if (S_ISDIR(stbuf.st_mode)) {
1144         flags |= AT_REMOVEDIR;
1145     }
1146
1147     err = local_unlinkat_common(ctx, dirfd, name, flags);
1148 err_out:
1149     close_preserve_errno(dirfd);
1150 out:
1151     g_free(name);
1152     g_free(dirpath);
1153     return err;
1154 }
1155
1156 static int local_fsync(FsContext *ctx, int fid_type,
1157                        V9fsFidOpenState *fs, int datasync)
1158 {
1159     int fd;
1160
1161     if (fid_type == P9_FID_DIR) {
1162         fd = dirfd(fs->dir.stream);
1163     } else {
1164         fd = fs->fd;
1165     }
1166
1167     if (datasync) {
1168         return qemu_fdatasync(fd);
1169     } else {
1170         return fsync(fd);
1171     }
1172 }
1173
1174 static int local_statfs(FsContext *s, V9fsPath *fs_path, struct statfs *stbuf)
1175 {
1176     int fd, ret;
1177
1178     fd = local_open_nofollow(s, fs_path->data, O_RDONLY, 0);
1179     if (fd == -1) {
1180         return -1;
1181     }
1182     ret = fstatfs(fd, stbuf);
1183     close_preserve_errno(fd);
1184     return ret;
1185 }
1186
1187 static ssize_t local_lgetxattr(FsContext *ctx, V9fsPath *fs_path,
1188                                const char *name, void *value, size_t size)
1189 {
1190     char *path = fs_path->data;
1191
1192     return v9fs_get_xattr(ctx, path, name, value, size);
1193 }
1194
1195 static ssize_t local_llistxattr(FsContext *ctx, V9fsPath *fs_path,
1196                                 void *value, size_t size)
1197 {
1198     char *path = fs_path->data;
1199
1200     return v9fs_list_xattr(ctx, path, value, size);
1201 }
1202
1203 static int local_lsetxattr(FsContext *ctx, V9fsPath *fs_path, const char *name,
1204                            void *value, size_t size, int flags)
1205 {
1206     char *path = fs_path->data;
1207
1208     return v9fs_set_xattr(ctx, path, name, value, size, flags);
1209 }
1210
1211 static int local_lremovexattr(FsContext *ctx, V9fsPath *fs_path,
1212                               const char *name)
1213 {
1214     char *path = fs_path->data;
1215
1216     return v9fs_remove_xattr(ctx, path, name);
1217 }
1218
1219 static int local_name_to_path(FsContext *ctx, V9fsPath *dir_path,
1220                               const char *name, V9fsPath *target)
1221 {
1222     if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
1223         local_is_mapped_file_metadata(ctx, name)) {
1224         errno = EINVAL;
1225         return -1;
1226     }
1227
1228     if (dir_path) {
1229         if (!strcmp(name, ".")) {
1230             /* "." relative to "foo/bar" is "foo/bar" */
1231             v9fs_path_copy(target, dir_path);
1232         } else if (!strcmp(name, "..")) {
1233             if (!strcmp(dir_path->data, ".")) {
1234                 /* ".." relative to the root is "." */
1235                 v9fs_path_sprintf(target, ".");
1236             } else {
1237                 char *tmp = g_path_get_dirname(dir_path->data);
1238                 /* Symbolic links are resolved by the client. We can assume
1239                  * that ".." relative to "foo/bar" is equivalent to "foo"
1240                  */
1241                 v9fs_path_sprintf(target, "%s", tmp);
1242                 g_free(tmp);
1243             }
1244         } else {
1245             assert(!strchr(name, '/'));
1246             v9fs_path_sprintf(target, "%s/%s", dir_path->data, name);
1247         }
1248     } else if (!strcmp(name, "/") || !strcmp(name, ".") ||
1249                !strcmp(name, "..")) {
1250             /* This is the root fid */
1251         v9fs_path_sprintf(target, ".");
1252     } else {
1253         assert(!strchr(name, '/'));
1254         v9fs_path_sprintf(target, "./%s", name);
1255     }
1256     return 0;
1257 }
1258
1259 static int local_renameat(FsContext *ctx, V9fsPath *olddir,
1260                           const char *old_name, V9fsPath *newdir,
1261                           const char *new_name)
1262 {
1263     int ret;
1264     int odirfd, ndirfd;
1265
1266     if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
1267         (local_is_mapped_file_metadata(ctx, old_name) ||
1268          local_is_mapped_file_metadata(ctx, new_name))) {
1269         errno = EINVAL;
1270         return -1;
1271     }
1272
1273     odirfd = local_opendir_nofollow(ctx, olddir->data);
1274     if (odirfd == -1) {
1275         return -1;
1276     }
1277
1278     ndirfd = local_opendir_nofollow(ctx, newdir->data);
1279     if (ndirfd == -1) {
1280         close_preserve_errno(odirfd);
1281         return -1;
1282     }
1283
1284     ret = renameat(odirfd, old_name, ndirfd, new_name);
1285     if (ret < 0) {
1286         goto out;
1287     }
1288
1289     if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1290         int omap_dirfd, nmap_dirfd;
1291
1292         ret = mkdirat(ndirfd, VIRTFS_META_DIR, 0700);
1293         if (ret < 0 && errno != EEXIST) {
1294             goto err_undo_rename;
1295         }
1296
1297         omap_dirfd = openat_dir(odirfd, VIRTFS_META_DIR);
1298         if (omap_dirfd == -1) {
1299             goto err;
1300         }
1301
1302         nmap_dirfd = openat_dir(ndirfd, VIRTFS_META_DIR);
1303         if (nmap_dirfd == -1) {
1304             close_preserve_errno(omap_dirfd);
1305             goto err;
1306         }
1307
1308         /* rename the .virtfs_metadata files */
1309         ret = renameat(omap_dirfd, old_name, nmap_dirfd, new_name);
1310         close_preserve_errno(nmap_dirfd);
1311         close_preserve_errno(omap_dirfd);
1312         if (ret < 0 && errno != ENOENT) {
1313             goto err_undo_rename;
1314         }
1315
1316         ret = 0;
1317     }
1318     goto out;
1319
1320 err:
1321     ret = -1;
1322 err_undo_rename:
1323     renameat_preserve_errno(ndirfd, new_name, odirfd, old_name);
1324 out:
1325     close_preserve_errno(ndirfd);
1326     close_preserve_errno(odirfd);
1327     return ret;
1328 }
1329
1330 static void v9fs_path_init_dirname(V9fsPath *path, const char *str)
1331 {
1332     path->data = g_path_get_dirname(str);
1333     path->size = strlen(path->data) + 1;
1334 }
1335
1336 static int local_rename(FsContext *ctx, const char *oldpath,
1337                         const char *newpath)
1338 {
1339     int err;
1340     char *oname = g_path_get_basename(oldpath);
1341     char *nname = g_path_get_basename(newpath);
1342     V9fsPath olddir, newdir;
1343
1344     v9fs_path_init_dirname(&olddir, oldpath);
1345     v9fs_path_init_dirname(&newdir, newpath);
1346
1347     err = local_renameat(ctx, &olddir, oname, &newdir, nname);
1348
1349     v9fs_path_free(&newdir);
1350     v9fs_path_free(&olddir);
1351     g_free(nname);
1352     g_free(oname);
1353
1354     return err;
1355 }
1356
1357 static int local_unlinkat(FsContext *ctx, V9fsPath *dir,
1358                           const char *name, int flags)
1359 {
1360     int ret;
1361     int dirfd;
1362
1363     if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
1364         local_is_mapped_file_metadata(ctx, name)) {
1365         errno = EINVAL;
1366         return -1;
1367     }
1368
1369     dirfd = local_opendir_nofollow(ctx, dir->data);
1370     if (dirfd == -1) {
1371         return -1;
1372     }
1373
1374     ret = local_unlinkat_common(ctx, dirfd, name, flags);
1375     close_preserve_errno(dirfd);
1376     return ret;
1377 }
1378
1379 #ifdef FS_IOC_GETVERSION
1380 static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
1381                                 mode_t st_mode, uint64_t *st_gen)
1382 {
1383     int err;
1384     V9fsFidOpenState fid_open;
1385
1386     /*
1387      * Do not try to open special files like device nodes, fifos etc
1388      * We can get fd for regular files and directories only
1389      */
1390     if (!S_ISREG(st_mode) && !S_ISDIR(st_mode)) {
1391         errno = ENOTTY;
1392         return -1;
1393     }
1394     err = local_open(ctx, path, O_RDONLY, &fid_open);
1395     if (err < 0) {
1396         return err;
1397     }
1398     err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
1399     local_close(ctx, &fid_open);
1400     return err;
1401 }
1402 #endif
1403
1404 static int local_ioc_getversion_init(FsContext *ctx, LocalData *data, Error **errp)
1405 {
1406 #ifdef FS_IOC_GETVERSION
1407     struct statfs stbuf;
1408
1409     /*
1410      * use ioc_getversion only if the ioctl is definied
1411      */
1412     if (fstatfs(data->mountfd, &stbuf) < 0) {
1413         error_setg_errno(errp, errno,
1414                          "failed to stat file system at '%s'", ctx->fs_root);
1415         return -1;
1416     }
1417     switch (stbuf.f_type) {
1418     case EXT2_SUPER_MAGIC:
1419     case BTRFS_SUPER_MAGIC:
1420     case REISERFS_SUPER_MAGIC:
1421     case XFS_SUPER_MAGIC:
1422         ctx->exops.get_st_gen = local_ioc_getversion;
1423         break;
1424     }
1425 #endif
1426     return 0;
1427 }
1428
1429 static int local_init(FsContext *ctx, Error **errp)
1430 {
1431     LocalData *data = g_malloc(sizeof(*data));
1432
1433     data->mountfd = open(ctx->fs_root, O_DIRECTORY | O_RDONLY);
1434     if (data->mountfd == -1) {
1435         error_setg_errno(errp, errno, "failed to open '%s'", ctx->fs_root);
1436         goto err;
1437     }
1438
1439     if (local_ioc_getversion_init(ctx, data, errp) < 0) {
1440         close(data->mountfd);
1441         goto err;
1442     }
1443
1444     if (ctx->export_flags & V9FS_SM_PASSTHROUGH) {
1445         ctx->xops = passthrough_xattr_ops;
1446     } else if (ctx->export_flags & V9FS_SM_MAPPED) {
1447         ctx->xops = mapped_xattr_ops;
1448     } else if (ctx->export_flags & V9FS_SM_NONE) {
1449         ctx->xops = none_xattr_ops;
1450     } else if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1451         /*
1452          * xattr operation for mapped-file and passthrough
1453          * remain same.
1454          */
1455         ctx->xops = passthrough_xattr_ops;
1456     }
1457     ctx->export_flags |= V9FS_PATHNAME_FSCONTEXT;
1458
1459     ctx->private = data;
1460     return 0;
1461
1462 err:
1463     g_free(data);
1464     return -1;
1465 }
1466
1467 static void local_cleanup(FsContext *ctx)
1468 {
1469     LocalData *data = ctx->private;
1470
1471     if (!data) {
1472         return;
1473     }
1474
1475     close(data->mountfd);
1476     g_free(data);
1477 }
1478
1479 static void error_append_security_model_hint(Error *const *errp)
1480 {
1481     error_append_hint(errp, "Valid options are: security_model="
1482                       "[passthrough|mapped-xattr|mapped-file|none]\n");
1483 }
1484
1485 static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)
1486 {
1487     ERRP_GUARD();
1488     const char *sec_model = qemu_opt_get(opts, "security_model");
1489     const char *path = qemu_opt_get(opts, "path");
1490     const char *multidevs = qemu_opt_get(opts, "multidevs");
1491
1492     if (!sec_model) {
1493         error_setg(errp, "security_model property not set");
1494         error_append_security_model_hint(errp);
1495         return -1;
1496     }
1497
1498     if (!strcmp(sec_model, "passthrough")) {
1499         fse->export_flags |= V9FS_SM_PASSTHROUGH;
1500     } else if (!strcmp(sec_model, "mapped") ||
1501                !strcmp(sec_model, "mapped-xattr")) {
1502         fse->export_flags |= V9FS_SM_MAPPED;
1503     } else if (!strcmp(sec_model, "none")) {
1504         fse->export_flags |= V9FS_SM_NONE;
1505     } else if (!strcmp(sec_model, "mapped-file")) {
1506         fse->export_flags |= V9FS_SM_MAPPED_FILE;
1507     } else {
1508         error_setg(errp, "invalid security_model property '%s'", sec_model);
1509         error_append_security_model_hint(errp);
1510         return -1;
1511     }
1512
1513     if (multidevs) {
1514         if (!strcmp(multidevs, "remap")) {
1515             fse->export_flags &= ~V9FS_FORBID_MULTIDEVS;
1516             fse->export_flags |= V9FS_REMAP_INODES;
1517         } else if (!strcmp(multidevs, "forbid")) {
1518             fse->export_flags &= ~V9FS_REMAP_INODES;
1519             fse->export_flags |= V9FS_FORBID_MULTIDEVS;
1520         } else if (!strcmp(multidevs, "warn")) {
1521             fse->export_flags &= ~V9FS_FORBID_MULTIDEVS;
1522             fse->export_flags &= ~V9FS_REMAP_INODES;
1523         } else {
1524             error_setg(errp, "invalid multidevs property '%s'",
1525                        multidevs);
1526             error_append_hint(errp, "Valid options are: multidevs="
1527                               "[remap|forbid|warn]\n");
1528             return -1;
1529         }
1530     }
1531
1532     if (!path) {
1533         error_setg(errp, "path property not set");
1534         return -1;
1535     }
1536
1537     if (fsdev_throttle_parse_opts(opts, &fse->fst, errp)) {
1538         error_prepend(errp, "invalid throttle configuration: ");
1539         return -1;
1540     }
1541
1542     if (fse->export_flags & V9FS_SM_MAPPED ||
1543         fse->export_flags & V9FS_SM_MAPPED_FILE) {
1544         fse->fmode =
1545             qemu_opt_get_number(opts, "fmode", SM_LOCAL_MODE_BITS) & 0777;
1546         fse->dmode =
1547             qemu_opt_get_number(opts, "dmode", SM_LOCAL_DIR_MODE_BITS) & 0777;
1548     } else {
1549         if (qemu_opt_find(opts, "fmode")) {
1550             error_setg(errp, "fmode is only valid for mapped security modes");
1551             return -1;
1552         }
1553         if (qemu_opt_find(opts, "dmode")) {
1554             error_setg(errp, "dmode is only valid for mapped security modes");
1555             return -1;
1556         }
1557     }
1558
1559     fse->path = g_strdup(path);
1560
1561     return 0;
1562 }
1563
1564 FileOperations local_ops = {
1565     .parse_opts = local_parse_opts,
1566     .init  = local_init,
1567     .cleanup = local_cleanup,
1568     .lstat = local_lstat,
1569     .readlink = local_readlink,
1570     .close = local_close,
1571     .closedir = local_closedir,
1572     .open = local_open,
1573     .opendir = local_opendir,
1574     .rewinddir = local_rewinddir,
1575     .telldir = local_telldir,
1576     .readdir = local_readdir,
1577     .seekdir = local_seekdir,
1578     .preadv = local_preadv,
1579     .pwritev = local_pwritev,
1580     .chmod = local_chmod,
1581     .mknod = local_mknod,
1582     .mkdir = local_mkdir,
1583     .fstat = local_fstat,
1584     .open2 = local_open2,
1585     .symlink = local_symlink,
1586     .link = local_link,
1587     .truncate = local_truncate,
1588     .rename = local_rename,
1589     .chown = local_chown,
1590     .utimensat = local_utimensat,
1591     .remove = local_remove,
1592     .fsync = local_fsync,
1593     .statfs = local_statfs,
1594     .lgetxattr = local_lgetxattr,
1595     .llistxattr = local_llistxattr,
1596     .lsetxattr = local_lsetxattr,
1597     .lremovexattr = local_lremovexattr,
1598     .name_to_path = local_name_to_path,
1599     .renameat  = local_renameat,
1600     .unlinkat = local_unlinkat,
1601 };