qemu/hw/9pfs/9p-local.c
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   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#ifdef CONFIG_LINUX
  36#include <linux/fs.h>
  37#ifdef CONFIG_LINUX_MAGIC_H
  38#include <linux/magic.h>
  39#endif
  40#endif
  41#include <sys/ioctl.h>
  42
  43#ifndef XFS_SUPER_MAGIC
  44#define XFS_SUPER_MAGIC  0x58465342
  45#endif
  46#ifndef EXT2_SUPER_MAGIC
  47#define EXT2_SUPER_MAGIC 0xEF53
  48#endif
  49#ifndef REISERFS_SUPER_MAGIC
  50#define REISERFS_SUPER_MAGIC 0x52654973
  51#endif
  52#ifndef BTRFS_SUPER_MAGIC
  53#define BTRFS_SUPER_MAGIC 0x9123683E
  54#endif
  55
  56typedef struct {
  57    int mountfd;
  58} LocalData;
  59
  60int local_open_nofollow(FsContext *fs_ctx, const char *path, int flags,
  61                        mode_t mode)
  62{
  63    LocalData *data = fs_ctx->private;
  64    int fd = data->mountfd;
  65
  66    while (*path && fd != -1) {
  67        const char *c;
  68        int next_fd;
  69        char *head;
  70
  71        /* Only relative paths without consecutive slashes */
  72        assert(*path != '/');
  73
  74        head = g_strdup(path);
  75        c = qemu_strchrnul(path, '/');
  76        if (*c) {
  77            /* Intermediate path element */
  78            head[c - path] = 0;
  79            path = c + 1;
  80            next_fd = openat_dir(fd, head);
  81        } else {
  82            /* Rightmost path element */
  83            next_fd = openat_file(fd, head, flags, mode);
  84            path = c;
  85        }
  86        g_free(head);
  87        if (fd != data->mountfd) {
  88            close_preserve_errno(fd);
  89        }
  90        fd = next_fd;
  91    }
  92
  93    assert(fd != data->mountfd);
  94    return fd;
  95}
  96
  97int local_opendir_nofollow(FsContext *fs_ctx, const char *path)
  98{
  99    return local_open_nofollow(fs_ctx, path, O_DIRECTORY | O_RDONLY, 0);
 100}
 101
 102static void renameat_preserve_errno(int odirfd, const char *opath, int ndirfd,
 103                                    const char *npath)
 104{
 105    int serrno = errno;
 106    qemu_renameat(odirfd, opath, ndirfd, npath);
 107    errno = serrno;
 108}
 109
 110static void unlinkat_preserve_errno(int dirfd, const char *path, int flags)
 111{
 112    int serrno = errno;
 113    qemu_unlinkat(dirfd, path, flags);
 114    errno = serrno;
 115}
 116
 117#define VIRTFS_META_DIR ".virtfs_metadata"
 118#define VIRTFS_META_ROOT_FILE VIRTFS_META_DIR "_root"
 119
 120static FILE *local_fopenat(int dirfd, const char *name, const char *mode)
 121{
 122    int fd, o_mode = 0;
 123    FILE *fp;
 124    int flags;
 125    /*
 126     * only supports two modes
 127     */
 128    if (mode[0] == 'r') {
 129        flags = O_RDONLY;
 130    } else if (mode[0] == 'w') {
 131        flags = O_WRONLY | O_TRUNC | O_CREAT;
 132        o_mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH;
 133    } else {
 134        return NULL;
 135    }
 136    fd = openat_file(dirfd, name, flags, o_mode);
 137    if (fd == -1) {
 138        return NULL;
 139    }
 140    fp = fdopen(fd, mode);
 141    if (!fp) {
 142        close(fd);
 143    }
 144    return fp;
 145}
 146
 147#define ATTR_MAX 100
 148static void local_mapped_file_attr(int dirfd, const char *name,
 149                                   struct stat *stbuf)
 150{
 151    FILE *fp;
 152    char buf[ATTR_MAX];
 153    int map_dirfd;
 154
 155    if (strcmp(name, ".")) {
 156        map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
 157        if (map_dirfd == -1) {
 158            return;
 159        }
 160
 161        fp = local_fopenat(map_dirfd, name, "r");
 162        close_preserve_errno(map_dirfd);
 163    } else {
 164        fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "r");
 165    }
 166    if (!fp) {
 167        return;
 168    }
 169    memset(buf, 0, ATTR_MAX);
 170    while (fgets(buf, ATTR_MAX, fp)) {
 171        if (!strncmp(buf, "virtfs.uid", 10)) {
 172            stbuf->st_uid = atoi(buf + 11);
 173        } else if (!strncmp(buf, "virtfs.gid", 10)) {
 174            stbuf->st_gid = atoi(buf + 11);
 175        } else if (!strncmp(buf, "virtfs.mode", 11)) {
 176            stbuf->st_mode = atoi(buf + 12);
 177        } else if (!strncmp(buf, "virtfs.rdev", 11)) {
 178            stbuf->st_rdev = atoi(buf + 12);
 179        }
 180        memset(buf, 0, ATTR_MAX);
 181    }
 182    fclose(fp);
 183}
 184
 185static int local_lstat(FsContext *fs_ctx, V9fsPath *fs_path, struct stat *stbuf)
 186{
 187    int err = -1;
 188    char *dirpath = g_path_get_dirname(fs_path->data);
 189    char *name = g_path_get_basename(fs_path->data);
 190    int dirfd;
 191
 192    dirfd = local_opendir_nofollow(fs_ctx, dirpath);
 193    if (dirfd == -1) {
 194        goto out;
 195    }
 196
 197    err = qemu_fstatat(dirfd, name, stbuf, AT_SYMLINK_NOFOLLOW);
 198    if (err) {
 199        goto err_out;
 200    }
 201    if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 202        /* Actual credentials are part of extended attrs */
 203        uid_t tmp_uid;
 204        gid_t tmp_gid;
 205        mode_t tmp_mode;
 206        dev_t tmp_dev;
 207
 208        if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.uid", &tmp_uid,
 209                                 sizeof(uid_t)) > 0) {
 210            stbuf->st_uid = le32_to_cpu(tmp_uid);
 211        }
 212        if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.gid", &tmp_gid,
 213                                 sizeof(gid_t)) > 0) {
 214            stbuf->st_gid = le32_to_cpu(tmp_gid);
 215        }
 216        if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.mode", &tmp_mode,
 217                                 sizeof(mode_t)) > 0) {
 218            stbuf->st_mode = le32_to_cpu(tmp_mode);
 219        }
 220        if (fgetxattrat_nofollow(dirfd, name, "user.virtfs.rdev", &tmp_dev,
 221                                 sizeof(dev_t)) > 0) {
 222            stbuf->st_rdev = le64_to_cpu(tmp_dev);
 223        }
 224    } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 225        local_mapped_file_attr(dirfd, name, stbuf);
 226    }
 227
 228err_out:
 229    close_preserve_errno(dirfd);
 230out:
 231    g_free(name);
 232    g_free(dirpath);
 233    return err;
 234}
 235
 236static int local_set_mapped_file_attrat(int dirfd, const char *name,
 237                                        FsCred *credp)
 238{
 239    FILE *fp;
 240    int ret;
 241    char buf[ATTR_MAX];
 242    int uid = -1, gid = -1, mode = -1, rdev = -1;
 243    int map_dirfd = -1, map_fd;
 244    bool is_root = !strcmp(name, ".");
 245
 246    if (is_root) {
 247        fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "r");
 248        if (!fp) {
 249            if (errno == ENOENT) {
 250                goto update_map_file;
 251            } else {
 252                return -1;
 253            }
 254        }
 255    } else {
 256        ret = qemu_mkdirat(dirfd, VIRTFS_META_DIR, 0700);
 257        if (ret < 0 && errno != EEXIST) {
 258            return -1;
 259        }
 260
 261        map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
 262        if (map_dirfd == -1) {
 263            return -1;
 264        }
 265
 266        fp = local_fopenat(map_dirfd, name, "r");
 267        if (!fp) {
 268            if (errno == ENOENT) {
 269                goto update_map_file;
 270            } else {
 271                close_preserve_errno(map_dirfd);
 272                return -1;
 273            }
 274        }
 275    }
 276    memset(buf, 0, ATTR_MAX);
 277    while (fgets(buf, ATTR_MAX, fp)) {
 278        if (!strncmp(buf, "virtfs.uid", 10)) {
 279            uid = atoi(buf + 11);
 280        } else if (!strncmp(buf, "virtfs.gid", 10)) {
 281            gid = atoi(buf + 11);
 282        } else if (!strncmp(buf, "virtfs.mode", 11)) {
 283            mode = atoi(buf + 12);
 284        } else if (!strncmp(buf, "virtfs.rdev", 11)) {
 285            rdev = atoi(buf + 12);
 286        }
 287        memset(buf, 0, ATTR_MAX);
 288    }
 289    fclose(fp);
 290
 291update_map_file:
 292    if (is_root) {
 293        fp = local_fopenat(dirfd, VIRTFS_META_ROOT_FILE, "w");
 294    } else {
 295        fp = local_fopenat(map_dirfd, name, "w");
 296        /* We can't go this far with map_dirfd not being a valid file descriptor
 297         * but some versions of gcc aren't smart enough to see it.
 298         */
 299        if (map_dirfd != -1) {
 300            close_preserve_errno(map_dirfd);
 301        }
 302    }
 303    if (!fp) {
 304        return -1;
 305    }
 306
 307    map_fd = fileno(fp);
 308    assert(map_fd != -1);
 309    ret = fchmod(map_fd, 0600);
 310    assert(ret == 0);
 311
 312    if (credp->fc_uid != -1) {
 313        uid = credp->fc_uid;
 314    }
 315    if (credp->fc_gid != -1) {
 316        gid = credp->fc_gid;
 317    }
 318    if (credp->fc_mode != (mode_t)-1) {
 319        mode = credp->fc_mode;
 320    }
 321    if (credp->fc_rdev != -1) {
 322        rdev = credp->fc_rdev;
 323    }
 324
 325    if (uid != -1) {
 326        fprintf(fp, "virtfs.uid=%d\n", uid);
 327    }
 328    if (gid != -1) {
 329        fprintf(fp, "virtfs.gid=%d\n", gid);
 330    }
 331    if (mode != -1) {
 332        fprintf(fp, "virtfs.mode=%d\n", mode);
 333    }
 334    if (rdev != -1) {
 335        fprintf(fp, "virtfs.rdev=%d\n", rdev);
 336    }
 337    fclose(fp);
 338
 339    return 0;
 340}
 341
 342static int fchmodat_nofollow(int dirfd, const char *name, mode_t mode)
 343{
 344    struct stat stbuf;
 345    int fd, ret;
 346
 347    /* FIXME: this should be handled with fchmodat(AT_SYMLINK_NOFOLLOW).
 348     * Unfortunately, the linux kernel doesn't implement it yet.
 349     */
 350
 351     /* First, we clear non-racing symlinks out of the way. */
 352    if (qemu_fstatat(dirfd, name, &stbuf, AT_SYMLINK_NOFOLLOW)) {
 353        return -1;
 354    }
 355    if (S_ISLNK(stbuf.st_mode)) {
 356        errno = ELOOP;
 357        return -1;
 358    }
 359
 360    fd = openat_file(dirfd, name, O_RDONLY | O_PATH_9P_UTIL | O_NOFOLLOW, 0);
 361#if O_PATH_9P_UTIL == 0
 362    /* Fallback for systems that don't support O_PATH: we depend on the file
 363     * being readable or writable.
 364     */
 365    if (fd == -1) {
 366        /* In case the file is writable-only and isn't a directory. */
 367        if (errno == EACCES) {
 368            fd = openat_file(dirfd, name, O_WRONLY, 0);
 369        }
 370        if (fd == -1 && errno == EISDIR) {
 371            errno = EACCES;
 372        }
 373    }
 374    if (fd == -1) {
 375        return -1;
 376    }
 377    ret = fchmod(fd, mode);
 378#else
 379    /* Access modes are ignored when O_PATH is supported. If name is a symbolic
 380     * link, O_PATH | O_NOFOLLOW causes openat(2) to return a file descriptor
 381     * referring to the symbolic link.
 382     */
 383    if (fd == -1) {
 384        return -1;
 385    }
 386
 387    /* Now we handle racing symlinks. */
 388    ret = fstat(fd, &stbuf);
 389    if (!ret) {
 390        if (S_ISLNK(stbuf.st_mode)) {
 391            errno = ELOOP;
 392            ret = -1;
 393        } else {
 394            char *proc_path = g_strdup_printf("/proc/self/fd/%d", fd);
 395            ret = chmod(proc_path, mode);
 396            g_free(proc_path);
 397        }
 398    }
 399#endif
 400    close_preserve_errno(fd);
 401    return ret;
 402}
 403
 404static int local_set_xattrat(int dirfd, const char *path, FsCred *credp)
 405{
 406    int err;
 407
 408    if (credp->fc_uid != -1) {
 409        uint32_t tmp_uid = cpu_to_le32(credp->fc_uid);
 410        err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.uid", &tmp_uid,
 411                                   sizeof(uid_t), 0);
 412        if (err) {
 413            return err;
 414        }
 415    }
 416    if (credp->fc_gid != -1) {
 417        uint32_t tmp_gid = cpu_to_le32(credp->fc_gid);
 418        err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.gid", &tmp_gid,
 419                                   sizeof(gid_t), 0);
 420        if (err) {
 421            return err;
 422        }
 423    }
 424    if (credp->fc_mode != (mode_t)-1) {
 425        uint32_t tmp_mode = cpu_to_le32(credp->fc_mode);
 426        err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.mode", &tmp_mode,
 427                                   sizeof(mode_t), 0);
 428        if (err) {
 429            return err;
 430        }
 431    }
 432    if (credp->fc_rdev != -1) {
 433        uint64_t tmp_rdev = cpu_to_le64(credp->fc_rdev);
 434        err = fsetxattrat_nofollow(dirfd, path, "user.virtfs.rdev", &tmp_rdev,
 435                                   sizeof(dev_t), 0);
 436        if (err) {
 437            return err;
 438        }
 439    }
 440    return 0;
 441}
 442
 443static int local_set_cred_passthrough(FsContext *fs_ctx, int dirfd,
 444                                      const char *name, FsCred *credp)
 445{
 446    if (fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
 447                 AT_SYMLINK_NOFOLLOW) < 0) {
 448        /*
 449         * If we fail to change ownership and if we are
 450         * using security model none. Ignore the error
 451         */
 452        if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
 453            return -1;
 454        }
 455    }
 456
 457    return fchmodat_nofollow(dirfd, name, credp->fc_mode & 07777);
 458}
 459
 460static ssize_t local_readlink(FsContext *fs_ctx, V9fsPath *fs_path,
 461                              char *buf, size_t bufsz)
 462{
 463    ssize_t tsize = -1;
 464
 465    if ((fs_ctx->export_flags & V9FS_SM_MAPPED) ||
 466        (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE)) {
 467        int fd;
 468
 469        fd = local_open_nofollow(fs_ctx, fs_path->data, O_RDONLY, 0);
 470        if (fd == -1) {
 471            return -1;
 472        }
 473        tsize = RETRY_ON_EINTR(read(fd, (void *)buf, bufsz));
 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
 495static int local_close(FsContext *ctx, V9fsFidOpenState *fs)
 496{
 497    return close(fs->fd);
 498}
 499
 500static int local_closedir(FsContext *ctx, V9fsFidOpenState *fs)
 501{
 502    return closedir(fs->dir.stream);
 503}
 504
 505static 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
 518static 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
 538static void local_rewinddir(FsContext *ctx, V9fsFidOpenState *fs)
 539{
 540    rewinddir(fs->dir.stream);
 541}
 542
 543static off_t local_telldir(FsContext *ctx, V9fsFidOpenState *fs)
 544{
 545    return telldir(fs->dir.stream);
 546}
 547
 548static 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
 554static struct dirent *local_readdir(FsContext *ctx, V9fsFidOpenState *fs)
 555{
 556    struct dirent *entry;
 557
 558again:
 559    entry = readdir(fs->dir.stream);
 560    if (!entry) {
 561        return NULL;
 562    }
 563#ifdef CONFIG_DARWIN
 564    int off;
 565    off = telldir(fs->dir.stream);
 566    /* If telldir fails, fail the entire readdir call */
 567    if (off < 0) {
 568        return NULL;
 569    }
 570    entry->d_seekoff = off;
 571#endif
 572
 573    if (ctx->export_flags & V9FS_SM_MAPPED) {
 574        entry->d_type = DT_UNKNOWN;
 575    } else if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 576        if (local_is_mapped_file_metadata(ctx, entry->d_name)) {
 577            /* skip the meta data */
 578            goto again;
 579        }
 580        entry->d_type = DT_UNKNOWN;
 581    }
 582
 583    return entry;
 584}
 585
 586static void local_seekdir(FsContext *ctx, V9fsFidOpenState *fs, off_t off)
 587{
 588    seekdir(fs->dir.stream, off);
 589}
 590
 591static ssize_t local_preadv(FsContext *ctx, V9fsFidOpenState *fs,
 592                            const struct iovec *iov,
 593                            int iovcnt, off_t offset)
 594{
 595#ifdef CONFIG_PREADV
 596    return preadv(fs->fd, iov, iovcnt, offset);
 597#else
 598    int err = lseek(fs->fd, offset, SEEK_SET);
 599    if (err == -1) {
 600        return err;
 601    } else {
 602        return readv(fs->fd, iov, iovcnt);
 603    }
 604#endif
 605}
 606
 607static ssize_t local_pwritev(FsContext *ctx, V9fsFidOpenState *fs,
 608                             const struct iovec *iov,
 609                             int iovcnt, off_t offset)
 610{
 611    ssize_t ret;
 612#ifdef CONFIG_PREADV
 613    ret = pwritev(fs->fd, iov, iovcnt, offset);
 614#else
 615    int err = lseek(fs->fd, offset, SEEK_SET);
 616    if (err == -1) {
 617        return err;
 618    } else {
 619        ret = writev(fs->fd, iov, iovcnt);
 620    }
 621#endif
 622#ifdef CONFIG_SYNC_FILE_RANGE
 623    if (ret > 0 && ctx->export_flags & V9FS_IMMEDIATE_WRITEOUT) {
 624        /*
 625         * Initiate a writeback. This is not a data integrity sync.
 626         * We want to ensure that we don't leave dirty pages in the cache
 627         * after write when writeout=immediate is sepcified.
 628         */
 629        sync_file_range(fs->fd, offset, ret,
 630                        SYNC_FILE_RANGE_WAIT_BEFORE | SYNC_FILE_RANGE_WRITE);
 631    }
 632#endif
 633    return ret;
 634}
 635
 636static int local_chmod(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
 637{
 638    char *dirpath = g_path_get_dirname(fs_path->data);
 639    char *name = g_path_get_basename(fs_path->data);
 640    int ret = -1;
 641    int dirfd;
 642
 643    dirfd = local_opendir_nofollow(fs_ctx, dirpath);
 644    if (dirfd == -1) {
 645        goto out;
 646    }
 647
 648    if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 649        ret = local_set_xattrat(dirfd, name, credp);
 650    } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 651        ret = local_set_mapped_file_attrat(dirfd, name, credp);
 652    } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 653               fs_ctx->export_flags & V9FS_SM_NONE) {
 654        ret = fchmodat_nofollow(dirfd, name, credp->fc_mode);
 655    }
 656    close_preserve_errno(dirfd);
 657
 658out:
 659    g_free(dirpath);
 660    g_free(name);
 661    return ret;
 662}
 663
 664static int local_mknod(FsContext *fs_ctx, V9fsPath *dir_path,
 665                       const char *name, FsCred *credp)
 666{
 667    int err = -1;
 668    int dirfd;
 669
 670    if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 671        local_is_mapped_file_metadata(fs_ctx, name)) {
 672        errno = EINVAL;
 673        return -1;
 674    }
 675
 676    dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 677    if (dirfd == -1) {
 678        return -1;
 679    }
 680
 681    if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 682        fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 683        err = qemu_mknodat(dirfd, name, fs_ctx->fmode | S_IFREG, 0);
 684        if (err == -1) {
 685            goto out;
 686        }
 687
 688        if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 689            err = local_set_xattrat(dirfd, name, credp);
 690        } else {
 691            err = local_set_mapped_file_attrat(dirfd, name, credp);
 692        }
 693        if (err == -1) {
 694            goto err_end;
 695        }
 696    } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 697               fs_ctx->export_flags & V9FS_SM_NONE) {
 698        err = qemu_mknodat(dirfd, name, credp->fc_mode, credp->fc_rdev);
 699        if (err == -1) {
 700            goto out;
 701        }
 702        err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
 703        if (err == -1) {
 704            goto err_end;
 705        }
 706    }
 707    goto out;
 708
 709err_end:
 710    unlinkat_preserve_errno(dirfd, name, 0);
 711out:
 712    close_preserve_errno(dirfd);
 713    return err;
 714}
 715
 716static int local_mkdir(FsContext *fs_ctx, V9fsPath *dir_path,
 717                       const char *name, FsCred *credp)
 718{
 719    int err = -1;
 720    int dirfd;
 721
 722    if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 723        local_is_mapped_file_metadata(fs_ctx, name)) {
 724        errno = EINVAL;
 725        return -1;
 726    }
 727
 728    dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 729    if (dirfd == -1) {
 730        return -1;
 731    }
 732
 733    if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 734        fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 735        err = qemu_mkdirat(dirfd, name, fs_ctx->dmode);
 736        if (err == -1) {
 737            goto out;
 738        }
 739        credp->fc_mode = credp->fc_mode | S_IFDIR;
 740
 741        if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 742            err = local_set_xattrat(dirfd, name, credp);
 743        } else {
 744            err = local_set_mapped_file_attrat(dirfd, name, credp);
 745        }
 746        if (err == -1) {
 747            goto err_end;
 748        }
 749    } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 750               fs_ctx->export_flags & V9FS_SM_NONE) {
 751        err = qemu_mkdirat(dirfd, name, credp->fc_mode);
 752        if (err == -1) {
 753            goto out;
 754        }
 755        err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
 756        if (err == -1) {
 757            goto err_end;
 758        }
 759    }
 760    goto out;
 761
 762err_end:
 763    unlinkat_preserve_errno(dirfd, name, AT_REMOVEDIR);
 764out:
 765    close_preserve_errno(dirfd);
 766    return err;
 767}
 768
 769static int local_fstat(FsContext *fs_ctx, int fid_type,
 770                       V9fsFidOpenState *fs, struct stat *stbuf)
 771{
 772    int err, fd;
 773
 774    if (fid_type == P9_FID_DIR) {
 775        fd = dirfd(fs->dir.stream);
 776    } else {
 777        fd = fs->fd;
 778    }
 779
 780    err = fstat(fd, stbuf);
 781    if (err) {
 782        return err;
 783    }
 784    if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 785        /* Actual credentials are part of extended attrs */
 786        uid_t tmp_uid;
 787        gid_t tmp_gid;
 788        mode_t tmp_mode;
 789        dev_t tmp_dev;
 790
 791        if (qemu_fgetxattr(fd, "user.virtfs.uid",
 792                           &tmp_uid, sizeof(uid_t)) > 0) {
 793            stbuf->st_uid = le32_to_cpu(tmp_uid);
 794        }
 795        if (qemu_fgetxattr(fd, "user.virtfs.gid",
 796                           &tmp_gid, sizeof(gid_t)) > 0) {
 797            stbuf->st_gid = le32_to_cpu(tmp_gid);
 798        }
 799        if (qemu_fgetxattr(fd, "user.virtfs.mode",
 800                           &tmp_mode, sizeof(mode_t)) > 0) {
 801            stbuf->st_mode = le32_to_cpu(tmp_mode);
 802        }
 803        if (qemu_fgetxattr(fd, "user.virtfs.rdev",
 804                           &tmp_dev, sizeof(dev_t)) > 0) {
 805            stbuf->st_rdev = le64_to_cpu(tmp_dev);
 806        }
 807    } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 808        errno = EOPNOTSUPP;
 809        return -1;
 810    }
 811    return err;
 812}
 813
 814static int local_open2(FsContext *fs_ctx, V9fsPath *dir_path, const char *name,
 815                       int flags, FsCred *credp, V9fsFidOpenState *fs)
 816{
 817    int fd = -1;
 818    int err = -1;
 819    int dirfd;
 820
 821    if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 822        local_is_mapped_file_metadata(fs_ctx, name)) {
 823        errno = EINVAL;
 824        return -1;
 825    }
 826
 827    /*
 828     * Mark all the open to not follow symlinks
 829     */
 830    flags |= O_NOFOLLOW;
 831
 832    dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 833    if (dirfd == -1) {
 834        return -1;
 835    }
 836
 837    /* Determine the security model */
 838    if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 839        fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 840        fd = openat_file(dirfd, name, flags, fs_ctx->fmode);
 841        if (fd == -1) {
 842            goto out;
 843        }
 844        credp->fc_mode = credp->fc_mode | S_IFREG;
 845        if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 846            /* Set cleint credentials in xattr */
 847            err = local_set_xattrat(dirfd, name, credp);
 848        } else {
 849            err = local_set_mapped_file_attrat(dirfd, name, credp);
 850        }
 851        if (err == -1) {
 852            goto err_end;
 853        }
 854    } else if ((fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
 855               (fs_ctx->export_flags & V9FS_SM_NONE)) {
 856        fd = openat_file(dirfd, name, flags, credp->fc_mode);
 857        if (fd == -1) {
 858            goto out;
 859        }
 860        err = local_set_cred_passthrough(fs_ctx, dirfd, name, credp);
 861        if (err == -1) {
 862            goto err_end;
 863        }
 864    }
 865    err = fd;
 866    fs->fd = fd;
 867    goto out;
 868
 869err_end:
 870    unlinkat_preserve_errno(dirfd, name,
 871                            flags & O_DIRECTORY ? AT_REMOVEDIR : 0);
 872    close_preserve_errno(fd);
 873out:
 874    close_preserve_errno(dirfd);
 875    return err;
 876}
 877
 878
 879static int local_symlink(FsContext *fs_ctx, const char *oldpath,
 880                         V9fsPath *dir_path, const char *name, FsCred *credp)
 881{
 882    int err = -1;
 883    int dirfd;
 884
 885    if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 886        local_is_mapped_file_metadata(fs_ctx, name)) {
 887        errno = EINVAL;
 888        return -1;
 889    }
 890
 891    dirfd = local_opendir_nofollow(fs_ctx, dir_path->data);
 892    if (dirfd == -1) {
 893        return -1;
 894    }
 895
 896    /* Determine the security model */
 897    if (fs_ctx->export_flags & V9FS_SM_MAPPED ||
 898        fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 899        int fd;
 900        ssize_t oldpath_size, write_size;
 901
 902        fd = openat_file(dirfd, name, O_CREAT | O_EXCL | O_RDWR,
 903                         fs_ctx->fmode);
 904        if (fd == -1) {
 905            goto out;
 906        }
 907        /* Write the oldpath (target) to the file. */
 908        oldpath_size = strlen(oldpath);
 909        write_size = RETRY_ON_EINTR(write(fd, (void *)oldpath, oldpath_size));
 910        close_preserve_errno(fd);
 911
 912        if (write_size != oldpath_size) {
 913            goto err_end;
 914        }
 915        /* Set cleint credentials in symlink's xattr */
 916        credp->fc_mode = credp->fc_mode | S_IFLNK;
 917
 918        if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
 919            err = local_set_xattrat(dirfd, name, credp);
 920        } else {
 921            err = local_set_mapped_file_attrat(dirfd, name, credp);
 922        }
 923        if (err == -1) {
 924            goto err_end;
 925        }
 926    } else if (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH ||
 927               fs_ctx->export_flags & V9FS_SM_NONE) {
 928        err = symlinkat(oldpath, dirfd, name);
 929        if (err) {
 930            goto out;
 931        }
 932        err = fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
 933                       AT_SYMLINK_NOFOLLOW);
 934        if (err == -1) {
 935            /*
 936             * If we fail to change ownership and if we are
 937             * using security model none. Ignore the error
 938             */
 939            if ((fs_ctx->export_flags & V9FS_SEC_MASK) != V9FS_SM_NONE) {
 940                goto err_end;
 941            } else {
 942                err = 0;
 943            }
 944        }
 945    }
 946    goto out;
 947
 948err_end:
 949    unlinkat_preserve_errno(dirfd, name, 0);
 950out:
 951    close_preserve_errno(dirfd);
 952    return err;
 953}
 954
 955static int local_link(FsContext *ctx, V9fsPath *oldpath,
 956                      V9fsPath *dirpath, const char *name)
 957{
 958    char *odirpath = g_path_get_dirname(oldpath->data);
 959    char *oname = g_path_get_basename(oldpath->data);
 960    int ret = -1;
 961    int odirfd, ndirfd;
 962
 963    if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
 964        local_is_mapped_file_metadata(ctx, name)) {
 965        errno = EINVAL;
 966        goto out;
 967    }
 968
 969    odirfd = local_opendir_nofollow(ctx, odirpath);
 970    if (odirfd == -1) {
 971        goto out;
 972    }
 973
 974    ndirfd = local_opendir_nofollow(ctx, dirpath->data);
 975    if (ndirfd == -1) {
 976        close_preserve_errno(odirfd);
 977        goto out;
 978    }
 979
 980    ret = linkat(odirfd, oname, ndirfd, name, 0);
 981    if (ret < 0) {
 982        goto out_close;
 983    }
 984
 985    /* now link the virtfs_metadata files */
 986    if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
 987        int omap_dirfd, nmap_dirfd;
 988
 989        ret = qemu_mkdirat(ndirfd, VIRTFS_META_DIR, 0700);
 990        if (ret < 0 && errno != EEXIST) {
 991            goto err_undo_link;
 992        }
 993
 994        omap_dirfd = openat_dir(odirfd, VIRTFS_META_DIR);
 995        if (omap_dirfd == -1) {
 996            goto err;
 997        }
 998
 999        nmap_dirfd = openat_dir(ndirfd, VIRTFS_META_DIR);
1000        if (nmap_dirfd == -1) {
1001            close_preserve_errno(omap_dirfd);
1002            goto err;
1003        }
1004
1005        ret = linkat(omap_dirfd, oname, nmap_dirfd, name, 0);
1006        close_preserve_errno(nmap_dirfd);
1007        close_preserve_errno(omap_dirfd);
1008        if (ret < 0 && errno != ENOENT) {
1009            goto err_undo_link;
1010        }
1011
1012        ret = 0;
1013    }
1014    goto out_close;
1015
1016err:
1017    ret = -1;
1018err_undo_link:
1019    unlinkat_preserve_errno(ndirfd, name, 0);
1020out_close:
1021    close_preserve_errno(ndirfd);
1022    close_preserve_errno(odirfd);
1023out:
1024    g_free(oname);
1025    g_free(odirpath);
1026    return ret;
1027}
1028
1029static int local_truncate(FsContext *ctx, V9fsPath *fs_path, off_t size)
1030{
1031    int fd, ret;
1032
1033    fd = local_open_nofollow(ctx, fs_path->data, O_WRONLY, 0);
1034    if (fd == -1) {
1035        return -1;
1036    }
1037    ret = ftruncate(fd, size);
1038    close_preserve_errno(fd);
1039    return ret;
1040}
1041
1042static int local_chown(FsContext *fs_ctx, V9fsPath *fs_path, FsCred *credp)
1043{
1044    char *dirpath = g_path_get_dirname(fs_path->data);
1045    char *name = g_path_get_basename(fs_path->data);
1046    int ret = -1;
1047    int dirfd;
1048
1049    dirfd = local_opendir_nofollow(fs_ctx, dirpath);
1050    if (dirfd == -1) {
1051        goto out;
1052    }
1053
1054    if ((credp->fc_uid == -1 && credp->fc_gid == -1) ||
1055        (fs_ctx->export_flags & V9FS_SM_PASSTHROUGH) ||
1056        (fs_ctx->export_flags & V9FS_SM_NONE)) {
1057        ret = fchownat(dirfd, name, credp->fc_uid, credp->fc_gid,
1058                       AT_SYMLINK_NOFOLLOW);
1059    } else if (fs_ctx->export_flags & V9FS_SM_MAPPED) {
1060        ret = local_set_xattrat(dirfd, name, credp);
1061    } else if (fs_ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1062        ret = local_set_mapped_file_attrat(dirfd, name, credp);
1063    }
1064
1065    close_preserve_errno(dirfd);
1066out:
1067    g_free(name);
1068    g_free(dirpath);
1069    return ret;
1070}
1071
1072static int local_utimensat(FsContext *s, V9fsPath *fs_path,
1073                           const struct timespec *buf)
1074{
1075    char *dirpath = g_path_get_dirname(fs_path->data);
1076    char *name = g_path_get_basename(fs_path->data);
1077    int dirfd, ret = -1;
1078
1079    dirfd = local_opendir_nofollow(s, dirpath);
1080    if (dirfd == -1) {
1081        goto out;
1082    }
1083
1084    ret = qemu_utimensat(dirfd, name, buf, AT_SYMLINK_NOFOLLOW);
1085    close_preserve_errno(dirfd);
1086out:
1087    g_free(dirpath);
1088    g_free(name);
1089    return ret;
1090}
1091
1092static int local_unlinkat_common(FsContext *ctx, int dirfd, const char *name,
1093                                 int flags)
1094{
1095    int ret;
1096
1097    if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1098        int map_dirfd;
1099
1100        /* We need to remove the metadata as well:
1101         * - the metadata directory if we're removing a directory
1102         * - the metadata file in the parent's metadata directory
1103         *
1104         * If any of these are missing (ie, ENOENT) then we're probably
1105         * trying to remove something that wasn't created in mapped-file
1106         * mode. We just ignore the error.
1107         */
1108        if (flags == AT_REMOVEDIR) {
1109            int fd;
1110
1111            fd = openat_dir(dirfd, name);
1112            if (fd == -1) {
1113                return -1;
1114            }
1115            ret = qemu_unlinkat(fd, VIRTFS_META_DIR, AT_REMOVEDIR);
1116            close_preserve_errno(fd);
1117            if (ret < 0 && errno != ENOENT) {
1118                return -1;
1119            }
1120        }
1121        map_dirfd = openat_dir(dirfd, VIRTFS_META_DIR);
1122        if (map_dirfd != -1) {
1123            ret = qemu_unlinkat(map_dirfd, name, 0);
1124            close_preserve_errno(map_dirfd);
1125            if (ret < 0 && errno != ENOENT) {
1126                return -1;
1127            }
1128        } else if (errno != ENOENT) {
1129            return -1;
1130        }
1131    }
1132
1133    return qemu_unlinkat(dirfd, name, flags);
1134}
1135
1136static int local_remove(FsContext *ctx, const char *path)
1137{
1138    struct stat stbuf;
1139    char *dirpath = g_path_get_dirname(path);
1140    char *name = g_path_get_basename(path);
1141    int flags = 0;
1142    int dirfd;
1143    int err = -1;
1144
1145    dirfd = local_opendir_nofollow(ctx, dirpath);
1146    if (dirfd == -1) {
1147        goto out;
1148    }
1149
1150    if (qemu_fstatat(dirfd, name, &stbuf, AT_SYMLINK_NOFOLLOW) < 0) {
1151        goto err_out;
1152    }
1153
1154    if (S_ISDIR(stbuf.st_mode)) {
1155        flags |= AT_REMOVEDIR;
1156    }
1157
1158    err = local_unlinkat_common(ctx, dirfd, name, flags);
1159err_out:
1160    close_preserve_errno(dirfd);
1161out:
1162    g_free(name);
1163    g_free(dirpath);
1164    return err;
1165}
1166
1167static int local_fsync(FsContext *ctx, int fid_type,
1168                       V9fsFidOpenState *fs, int datasync)
1169{
1170    int fd;
1171
1172    if (fid_type == P9_FID_DIR) {
1173        fd = dirfd(fs->dir.stream);
1174    } else {
1175        fd = fs->fd;
1176    }
1177
1178    if (datasync) {
1179        return qemu_fdatasync(fd);
1180    } else {
1181        return fsync(fd);
1182    }
1183}
1184
1185static int local_statfs(FsContext *s, V9fsPath *fs_path, struct statfs *stbuf)
1186{
1187    int fd, ret;
1188
1189    fd = local_open_nofollow(s, fs_path->data, O_RDONLY, 0);
1190    if (fd == -1) {
1191        return -1;
1192    }
1193    ret = fstatfs(fd, stbuf);
1194    close_preserve_errno(fd);
1195    return ret;
1196}
1197
1198static ssize_t local_lgetxattr(FsContext *ctx, V9fsPath *fs_path,
1199                               const char *name, void *value, size_t size)
1200{
1201    char *path = fs_path->data;
1202
1203    return v9fs_get_xattr(ctx, path, name, value, size);
1204}
1205
1206static ssize_t local_llistxattr(FsContext *ctx, V9fsPath *fs_path,
1207                                void *value, size_t size)
1208{
1209    char *path = fs_path->data;
1210
1211    return v9fs_list_xattr(ctx, path, value, size);
1212}
1213
1214static int local_lsetxattr(FsContext *ctx, V9fsPath *fs_path, const char *name,
1215                           void *value, size_t size, int flags)
1216{
1217    char *path = fs_path->data;
1218
1219    return v9fs_set_xattr(ctx, path, name, value, size, flags);
1220}
1221
1222static int local_lremovexattr(FsContext *ctx, V9fsPath *fs_path,
1223                              const char *name)
1224{
1225    char *path = fs_path->data;
1226
1227    return v9fs_remove_xattr(ctx, path, name);
1228}
1229
1230static int local_name_to_path(FsContext *ctx, V9fsPath *dir_path,
1231                              const char *name, V9fsPath *target)
1232{
1233    if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
1234        local_is_mapped_file_metadata(ctx, name)) {
1235        errno = EINVAL;
1236        return -1;
1237    }
1238
1239    if (dir_path) {
1240        if (!strcmp(name, ".")) {
1241            /* "." relative to "foo/bar" is "foo/bar" */
1242            v9fs_path_copy(target, dir_path);
1243        } else if (!strcmp(name, "..")) {
1244            if (!strcmp(dir_path->data, ".")) {
1245                /* ".." relative to the root is "." */
1246                v9fs_path_sprintf(target, ".");
1247            } else {
1248                char *tmp = g_path_get_dirname(dir_path->data);
1249                /* Symbolic links are resolved by the client. We can assume
1250                 * that ".." relative to "foo/bar" is equivalent to "foo"
1251                 */
1252                v9fs_path_sprintf(target, "%s", tmp);
1253                g_free(tmp);
1254            }
1255        } else {
1256            assert(!strchr(name, '/'));
1257            v9fs_path_sprintf(target, "%s/%s", dir_path->data, name);
1258        }
1259    } else if (!strcmp(name, "/") || !strcmp(name, ".") ||
1260               !strcmp(name, "..")) {
1261            /* This is the root fid */
1262        v9fs_path_sprintf(target, ".");
1263    } else {
1264        assert(!strchr(name, '/'));
1265        v9fs_path_sprintf(target, "./%s", name);
1266    }
1267    return 0;
1268}
1269
1270static int local_renameat(FsContext *ctx, V9fsPath *olddir,
1271                          const char *old_name, V9fsPath *newdir,
1272                          const char *new_name)
1273{
1274    int ret;
1275    int odirfd, ndirfd;
1276
1277    if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
1278        (local_is_mapped_file_metadata(ctx, old_name) ||
1279         local_is_mapped_file_metadata(ctx, new_name))) {
1280        errno = EINVAL;
1281        return -1;
1282    }
1283
1284    odirfd = local_opendir_nofollow(ctx, olddir->data);
1285    if (odirfd == -1) {
1286        return -1;
1287    }
1288
1289    ndirfd = local_opendir_nofollow(ctx, newdir->data);
1290    if (ndirfd == -1) {
1291        close_preserve_errno(odirfd);
1292        return -1;
1293    }
1294
1295    ret = qemu_renameat(odirfd, old_name, ndirfd, new_name);
1296    if (ret < 0) {
1297        goto out;
1298    }
1299
1300    if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1301        int omap_dirfd, nmap_dirfd;
1302
1303        ret = qemu_mkdirat(ndirfd, VIRTFS_META_DIR, 0700);
1304        if (ret < 0 && errno != EEXIST) {
1305            goto err_undo_rename;
1306        }
1307
1308        omap_dirfd = openat_dir(odirfd, VIRTFS_META_DIR);
1309        if (omap_dirfd == -1) {
1310            goto err;
1311        }
1312
1313        nmap_dirfd = openat_dir(ndirfd, VIRTFS_META_DIR);
1314        if (nmap_dirfd == -1) {
1315            close_preserve_errno(omap_dirfd);
1316            goto err;
1317        }
1318
1319        /* rename the .virtfs_metadata files */
1320        ret = qemu_renameat(omap_dirfd, old_name, nmap_dirfd, new_name);
1321        close_preserve_errno(nmap_dirfd);
1322        close_preserve_errno(omap_dirfd);
1323        if (ret < 0 && errno != ENOENT) {
1324            goto err_undo_rename;
1325        }
1326
1327        ret = 0;
1328    }
1329    goto out;
1330
1331err:
1332    ret = -1;
1333err_undo_rename:
1334    renameat_preserve_errno(ndirfd, new_name, odirfd, old_name);
1335out:
1336    close_preserve_errno(ndirfd);
1337    close_preserve_errno(odirfd);
1338    return ret;
1339}
1340
1341static void v9fs_path_init_dirname(V9fsPath *path, const char *str)
1342{
1343    path->data = g_path_get_dirname(str);
1344    path->size = strlen(path->data) + 1;
1345}
1346
1347static int local_rename(FsContext *ctx, const char *oldpath,
1348                        const char *newpath)
1349{
1350    int err;
1351    char *oname = g_path_get_basename(oldpath);
1352    char *nname = g_path_get_basename(newpath);
1353    V9fsPath olddir, newdir;
1354
1355    v9fs_path_init_dirname(&olddir, oldpath);
1356    v9fs_path_init_dirname(&newdir, newpath);
1357
1358    err = local_renameat(ctx, &olddir, oname, &newdir, nname);
1359
1360    v9fs_path_free(&newdir);
1361    v9fs_path_free(&olddir);
1362    g_free(nname);
1363    g_free(oname);
1364
1365    return err;
1366}
1367
1368static int local_unlinkat(FsContext *ctx, V9fsPath *dir,
1369                          const char *name, int flags)
1370{
1371    int ret;
1372    int dirfd;
1373
1374    if (ctx->export_flags & V9FS_SM_MAPPED_FILE &&
1375        local_is_mapped_file_metadata(ctx, name)) {
1376        errno = EINVAL;
1377        return -1;
1378    }
1379
1380    dirfd = local_opendir_nofollow(ctx, dir->data);
1381    if (dirfd == -1) {
1382        return -1;
1383    }
1384
1385    ret = local_unlinkat_common(ctx, dirfd, name, flags);
1386    close_preserve_errno(dirfd);
1387    return ret;
1388}
1389
1390#ifdef FS_IOC_GETVERSION
1391static int local_ioc_getversion(FsContext *ctx, V9fsPath *path,
1392                                mode_t st_mode, uint64_t *st_gen)
1393{
1394    int err;
1395    V9fsFidOpenState fid_open;
1396
1397    /*
1398     * Do not try to open special files like device nodes, fifos etc
1399     * We can get fd for regular files and directories only
1400     */
1401    if (!S_ISREG(st_mode) && !S_ISDIR(st_mode)) {
1402        errno = ENOTTY;
1403        return -1;
1404    }
1405    err = local_open(ctx, path, O_RDONLY, &fid_open);
1406    if (err < 0) {
1407        return err;
1408    }
1409    err = ioctl(fid_open.fd, FS_IOC_GETVERSION, st_gen);
1410    local_close(ctx, &fid_open);
1411    return err;
1412}
1413#endif
1414
1415static int local_ioc_getversion_init(FsContext *ctx, LocalData *data, Error **errp)
1416{
1417#ifdef FS_IOC_GETVERSION
1418    struct statfs stbuf;
1419
1420    /*
1421     * use ioc_getversion only if the ioctl is definied
1422     */
1423    if (fstatfs(data->mountfd, &stbuf) < 0) {
1424        error_setg_errno(errp, errno,
1425                         "failed to stat file system at '%s'", ctx->fs_root);
1426        return -1;
1427    }
1428    switch (stbuf.f_type) {
1429    case EXT2_SUPER_MAGIC:
1430    case BTRFS_SUPER_MAGIC:
1431    case REISERFS_SUPER_MAGIC:
1432    case XFS_SUPER_MAGIC:
1433        ctx->exops.get_st_gen = local_ioc_getversion;
1434        break;
1435    }
1436#endif
1437    return 0;
1438}
1439
1440static int local_init(FsContext *ctx, Error **errp)
1441{
1442    LocalData *data = g_malloc(sizeof(*data));
1443
1444    data->mountfd = open(ctx->fs_root, O_DIRECTORY | O_RDONLY);
1445    if (data->mountfd == -1) {
1446        error_setg_errno(errp, errno, "failed to open '%s'", ctx->fs_root);
1447        goto err;
1448    }
1449
1450    if (local_ioc_getversion_init(ctx, data, errp) < 0) {
1451        close(data->mountfd);
1452        goto err;
1453    }
1454
1455    if (ctx->export_flags & V9FS_SM_PASSTHROUGH) {
1456        ctx->xops = passthrough_xattr_ops;
1457    } else if (ctx->export_flags & V9FS_SM_MAPPED) {
1458        ctx->xops = mapped_xattr_ops;
1459    } else if (ctx->export_flags & V9FS_SM_NONE) {
1460        ctx->xops = none_xattr_ops;
1461    } else if (ctx->export_flags & V9FS_SM_MAPPED_FILE) {
1462        /*
1463         * xattr operation for mapped-file and passthrough
1464         * remain same.
1465         */
1466        ctx->xops = passthrough_xattr_ops;
1467    }
1468    ctx->export_flags |= V9FS_PATHNAME_FSCONTEXT;
1469
1470    ctx->private = data;
1471    return 0;
1472
1473err:
1474    g_free(data);
1475    return -1;
1476}
1477
1478static void local_cleanup(FsContext *ctx)
1479{
1480    LocalData *data = ctx->private;
1481
1482    if (!data) {
1483        return;
1484    }
1485
1486    close(data->mountfd);
1487    g_free(data);
1488}
1489
1490static void error_append_security_model_hint(Error *const *errp)
1491{
1492    error_append_hint(errp, "Valid options are: security_model="
1493                      "[passthrough|mapped-xattr|mapped-file|none]\n");
1494}
1495
1496static int local_parse_opts(QemuOpts *opts, FsDriverEntry *fse, Error **errp)
1497{
1498    ERRP_GUARD();
1499    const char *sec_model = qemu_opt_get(opts, "security_model");
1500    const char *path = qemu_opt_get(opts, "path");
1501    const char *multidevs = qemu_opt_get(opts, "multidevs");
1502
1503    if (!sec_model) {
1504        error_setg(errp, "security_model property not set");
1505        error_append_security_model_hint(errp);
1506        return -1;
1507    }
1508
1509    if (!strcmp(sec_model, "passthrough")) {
1510        fse->export_flags |= V9FS_SM_PASSTHROUGH;
1511    } else if (!strcmp(sec_model, "mapped") ||
1512               !strcmp(sec_model, "mapped-xattr")) {
1513        fse->export_flags |= V9FS_SM_MAPPED;
1514    } else if (!strcmp(sec_model, "none")) {
1515        fse->export_flags |= V9FS_SM_NONE;
1516    } else if (!strcmp(sec_model, "mapped-file")) {
1517        fse->export_flags |= V9FS_SM_MAPPED_FILE;
1518    } else {
1519        error_setg(errp, "invalid security_model property '%s'", sec_model);
1520        error_append_security_model_hint(errp);
1521        return -1;
1522    }
1523
1524    if (multidevs) {
1525        if (!strcmp(multidevs, "remap")) {
1526            fse->export_flags &= ~V9FS_FORBID_MULTIDEVS;
1527            fse->export_flags |= V9FS_REMAP_INODES;
1528        } else if (!strcmp(multidevs, "forbid")) {
1529            fse->export_flags &= ~V9FS_REMAP_INODES;
1530            fse->export_flags |= V9FS_FORBID_MULTIDEVS;
1531        } else if (!strcmp(multidevs, "warn")) {
1532            fse->export_flags &= ~V9FS_FORBID_MULTIDEVS;
1533            fse->export_flags &= ~V9FS_REMAP_INODES;
1534        } else {
1535            error_setg(errp, "invalid multidevs property '%s'",
1536                       multidevs);
1537            error_append_hint(errp, "Valid options are: multidevs="
1538                              "[remap|forbid|warn]\n");
1539            return -1;
1540        }
1541    }
1542
1543    if (!path) {
1544        error_setg(errp, "path property not set");
1545        return -1;
1546    }
1547
1548    if (fsdev_throttle_parse_opts(opts, &fse->fst, errp)) {
1549        error_prepend(errp, "invalid throttle configuration: ");
1550        return -1;
1551    }
1552
1553    if (fse->export_flags & V9FS_SM_MAPPED ||
1554        fse->export_flags & V9FS_SM_MAPPED_FILE) {
1555        fse->fmode =
1556            qemu_opt_get_number(opts, "fmode", SM_LOCAL_MODE_BITS) & 0777;
1557        fse->dmode =
1558            qemu_opt_get_number(opts, "dmode", SM_LOCAL_DIR_MODE_BITS) & 0777;
1559    } else {
1560        if (qemu_opt_find(opts, "fmode")) {
1561            error_setg(errp, "fmode is only valid for mapped security modes");
1562            return -1;
1563        }
1564        if (qemu_opt_find(opts, "dmode")) {
1565            error_setg(errp, "dmode is only valid for mapped security modes");
1566            return -1;
1567        }
1568    }
1569
1570    fse->path = g_strdup(path);
1571
1572    return 0;
1573}
1574
1575FileOperations local_ops = {
1576    .parse_opts = local_parse_opts,
1577    .init  = local_init,
1578    .cleanup = local_cleanup,
1579    .lstat = local_lstat,
1580    .readlink = local_readlink,
1581    .close = local_close,
1582    .closedir = local_closedir,
1583    .open = local_open,
1584    .opendir = local_opendir,
1585    .rewinddir = local_rewinddir,
1586    .telldir = local_telldir,
1587    .readdir = local_readdir,
1588    .seekdir = local_seekdir,
1589    .preadv = local_preadv,
1590    .pwritev = local_pwritev,
1591    .chmod = local_chmod,
1592    .mknod = local_mknod,
1593    .mkdir = local_mkdir,
1594    .fstat = local_fstat,
1595    .open2 = local_open2,
1596    .symlink = local_symlink,
1597    .link = local_link,
1598    .truncate = local_truncate,
1599    .rename = local_rename,
1600    .chown = local_chown,
1601    .utimensat = local_utimensat,
1602    .remove = local_remove,
1603    .fsync = local_fsync,
1604    .statfs = local_statfs,
1605    .lgetxattr = local_lgetxattr,
1606    .llistxattr = local_llistxattr,
1607    .lsetxattr = local_lsetxattr,
1608    .lremovexattr = local_lremovexattr,
1609    .name_to_path = local_name_to_path,
1610    .renameat  = local_renameat,
1611    .unlinkat = local_unlinkat,
1612};
1613