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