hw/virtio-9p-local.c

   1 /*
   2  * Virtio 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 "virtio.h"
  14 #include "virtio-9p.h"
  15 #include <arpa/inet.h>
  16 #include <pwd.h>
  17 #include <grp.h>
  18 #include <sys/socket.h>
  19 #include <sys/un.h>
  20 #include <attr/xattr.h>
  21
  22 static const char *rpath(FsContext *ctx, const char *path)
  23 {
  24     /* FIXME: so wrong... */
  25     static char buffer[4096];
  26     snprintf(buffer, sizeof(buffer), "%s/%s", ctx->fs_root, path);
  27     return buffer;
  28 }
  29
  30
  31 static int local_lstat(FsContext *fs_ctx, const char *path, struct stat *stbuf)
  32 {
  33     int err;
  34     err =  lstat(rpath(fs_ctx, path), stbuf);
  35     if (err) {
  36         return err;
  37     }
  38     if (fs_ctx->fs_sm == SM_MAPPED) {
  39         /* Actual credentials are part of extended attrs */
  40         uid_t tmp_uid;
  41         gid_t tmp_gid;
  42         mode_t tmp_mode;
  43         dev_t tmp_dev;
  44         if (getxattr(rpath(fs_ctx, path), "user.virtfs.uid", &tmp_uid,
  45                     sizeof(uid_t)) > 0) {
  46             stbuf->st_uid = tmp_uid;
  47         }
  48         if (getxattr(rpath(fs_ctx, path), "user.virtfs.gid", &tmp_gid,
  49                     sizeof(gid_t)) > 0) {
  50             stbuf->st_gid = tmp_gid;
  51         }
  52         if (getxattr(rpath(fs_ctx, path), "user.virtfs.mode", &tmp_mode,
  53                     sizeof(mode_t)) > 0) {
  54             stbuf->st_mode = tmp_mode;
  55         }
  56         if (getxattr(rpath(fs_ctx, path), "user.virtfs.rdev", &tmp_dev,
  57                         sizeof(dev_t)) > 0) {
  58                 stbuf->st_rdev = tmp_dev;
  59         }
  60     }
  61     return err;
  62 }
  63
  64 static int local_set_xattr(const char *path, FsCred *credp)
  65 {
  66     int err;
  67     if (credp->fc_uid != -1) {
  68         err = setxattr(path, "user.virtfs.uid", &credp->fc_uid, sizeof(uid_t),
  69                 0);
  70         if (err) {
  71             return err;
  72         }
  73     }
  74     if (credp->fc_gid != -1) {
  75         err = setxattr(path, "user.virtfs.gid", &credp->fc_gid, sizeof(gid_t),
  76                 0);
  77         if (err) {
  78             return err;
  79         }
  80     }
  81     if (credp->fc_mode != -1) {
  82         err = setxattr(path, "user.virtfs.mode", &credp->fc_mode,
  83                 sizeof(mode_t), 0);
  84         if (err) {
  85             return err;
  86         }
  87     }
  88     if (credp->fc_rdev != -1) {
  89         err = setxattr(path, "user.virtfs.rdev", &credp->fc_rdev,
  90                 sizeof(dev_t), 0);
  91         if (err) {
  92             return err;
  93         }
  94     }
  95     return 0;
  96 }
  97
  98 static int local_post_create_passthrough(FsContext *fs_ctx, const char *path,
  99         FsCred *credp)
 100 {
 101     if (chmod(rpath(fs_ctx, path), credp->fc_mode & 07777) < 0) {
 102         return -1;
 103     }
 104     if (chown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid) < 0) {
 105         return -1;
 106     }
 107     return 0;
 108 }
 109
 110 static ssize_t local_readlink(FsContext *fs_ctx, const char *path,
 111         char *buf, size_t bufsz)
 112 {
 113     ssize_t tsize = -1;
 114     if (fs_ctx->fs_sm == SM_MAPPED) {
 115         int fd;
 116         fd = open(rpath(fs_ctx, path), O_RDONLY);
 117         if (fd == -1) {
 118             return -1;
 119         }
 120         do {
 121             tsize = read(fd, (void *)buf, bufsz);
 122         } while (tsize == -1 && errno == EINTR);
 123         close(fd);
 124         return tsize;
 125     } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
 126         tsize = readlink(rpath(fs_ctx, path), buf, bufsz);
 127     }
 128     return tsize;
 129 }
 130
 131 static int local_close(FsContext *ctx, int fd)
 132 {
 133     return close(fd);
 134 }
 135
 136 static int local_closedir(FsContext *ctx, DIR *dir)
 137 {
 138     return closedir(dir);
 139 }
 140
 141 static int local_open(FsContext *ctx, const char *path, int flags)
 142 {
 143     return open(rpath(ctx, path), flags);
 144 }
 145
 146 static DIR *local_opendir(FsContext *ctx, const char *path)
 147 {
 148     return opendir(rpath(ctx, path));
 149 }
 150
 151 static void local_rewinddir(FsContext *ctx, DIR *dir)
 152 {
 153     return rewinddir(dir);
 154 }
 155
 156 static off_t local_telldir(FsContext *ctx, DIR *dir)
 157 {
 158     return telldir(dir);
 159 }
 160
 161 static struct dirent *local_readdir(FsContext *ctx, DIR *dir)
 162 {
 163     return readdir(dir);
 164 }
 165
 166 static void local_seekdir(FsContext *ctx, DIR *dir, off_t off)
 167 {
 168     return seekdir(dir, off);
 169 }
 170
 171 static ssize_t local_readv(FsContext *ctx, int fd, const struct iovec *iov,
 172                             int iovcnt)
 173 {
 174     return readv(fd, iov, iovcnt);
 175 }
 176
 177 static off_t local_lseek(FsContext *ctx, int fd, off_t offset, int whence)
 178 {
 179     return lseek(fd, offset, whence);
 180 }
 181
 182 static ssize_t local_writev(FsContext *ctx, int fd, const struct iovec *iov,
 183                             int iovcnt)
 184 {
 185     return writev(fd, iov, iovcnt);
 186 }
 187
 188 static int local_chmod(FsContext *fs_ctx, const char *path, FsCred *credp)
 189 {
 190     if (fs_ctx->fs_sm == SM_MAPPED) {
 191         return local_set_xattr(rpath(fs_ctx, path), credp);
 192     } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
 193         return chmod(rpath(fs_ctx, path), credp->fc_mode);
 194     }
 195     return -1;
 196 }
 197
 198 static int local_mknod(FsContext *fs_ctx, const char *path, FsCred *credp)
 199 {
 200     int err = -1;
 201     int serrno = 0;
 202
 203     /* Determine the security model */
 204     if (fs_ctx->fs_sm == SM_MAPPED) {
 205         err = mknod(rpath(fs_ctx, path), SM_LOCAL_MODE_BITS|S_IFREG, 0);
 206         if (err == -1) {
 207             return err;
 208         }
 209         local_set_xattr(rpath(fs_ctx, path), credp);
 210         if (err == -1) {
 211             serrno = errno;
 212             goto err_end;
 213         }
 214     } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
 215         err = mknod(rpath(fs_ctx, path), credp->fc_mode, credp->fc_rdev);
 216         if (err == -1) {
 217             return err;
 218         }
 219         err = local_post_create_passthrough(fs_ctx, path, credp);
 220         if (err == -1) {
 221             serrno = errno;
 222             goto err_end;
 223         }
 224     }
 225     return err;
 226
 227 err_end:
 228     remove(rpath(fs_ctx, path));
 229     errno = serrno;
 230     return err;
 231 }
 232
 233 static int local_mkdir(FsContext *fs_ctx, const char *path, FsCred *credp)
 234 {
 235     int err = -1;
 236     int serrno = 0;
 237
 238     /* Determine the security model */
 239     if (fs_ctx->fs_sm == SM_MAPPED) {
 240         err = mkdir(rpath(fs_ctx, path), SM_LOCAL_DIR_MODE_BITS);
 241         if (err == -1) {
 242             return err;
 243         }
 244         credp->fc_mode = credp->fc_mode|S_IFDIR;
 245         err = local_set_xattr(rpath(fs_ctx, path), credp);
 246         if (err == -1) {
 247             serrno = errno;
 248             goto err_end;
 249         }
 250     } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
 251         err = mkdir(rpath(fs_ctx, path), credp->fc_mode);
 252         if (err == -1) {
 253             return err;
 254         }
 255         err = local_post_create_passthrough(fs_ctx, path, credp);
 256         if (err == -1) {
 257             serrno = errno;
 258             goto err_end;
 259         }
 260     }
 261     return err;
 262
 263 err_end:
 264     remove(rpath(fs_ctx, path));
 265     errno = serrno;
 266     return err;
 267 }
 268
 269 static int local_fstat(FsContext *fs_ctx, int fd, struct stat *stbuf)
 270 {
 271     int err;
 272     err = fstat(fd, stbuf);
 273     if (err) {
 274         return err;
 275     }
 276     if (fs_ctx->fs_sm == SM_MAPPED) {
 277         /* Actual credentials are part of extended attrs */
 278         uid_t tmp_uid;
 279         gid_t tmp_gid;
 280         mode_t tmp_mode;
 281         dev_t tmp_dev;
 282
 283         if (fgetxattr(fd, "user.virtfs.uid", &tmp_uid, sizeof(uid_t)) > 0) {
 284             stbuf->st_uid = tmp_uid;
 285         }
 286         if (fgetxattr(fd, "user.virtfs.gid", &tmp_gid, sizeof(gid_t)) > 0) {
 287             stbuf->st_gid = tmp_gid;
 288         }
 289         if (fgetxattr(fd, "user.virtfs.mode", &tmp_mode, sizeof(mode_t)) > 0) {
 290             stbuf->st_mode = tmp_mode;
 291         }
 292         if (fgetxattr(fd, "user.virtfs.rdev", &tmp_dev, sizeof(dev_t)) > 0) {
 293                 stbuf->st_rdev = tmp_dev;
 294         }
 295     }
 296     return err;
 297 }
 298
 299 static int local_open2(FsContext *fs_ctx, const char *path, int flags,
 300         FsCred *credp)
 301 {
 302     int fd = -1;
 303     int err = -1;
 304     int serrno = 0;
 305
 306     /* Determine the security model */
 307     if (fs_ctx->fs_sm == SM_MAPPED) {
 308         fd = open(rpath(fs_ctx, path), flags, SM_LOCAL_MODE_BITS);
 309         if (fd == -1) {
 310             return fd;
 311         }
 312         credp->fc_mode = credp->fc_mode|S_IFREG;
 313         /* Set cleint credentials in xattr */
 314         err = local_set_xattr(rpath(fs_ctx, path), credp);
 315         if (err == -1) {
 316             serrno = errno;
 317             goto err_end;
 318         }
 319     } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
 320         fd = open(rpath(fs_ctx, path), flags, credp->fc_mode);
 321         if (fd == -1) {
 322             return fd;
 323         }
 324         err = local_post_create_passthrough(fs_ctx, path, credp);
 325         if (err == -1) {
 326             serrno = errno;
 327             goto err_end;
 328         }
 329     }
 330     return fd;
 331
 332 err_end:
 333     close(fd);
 334     remove(rpath(fs_ctx, path));
 335     errno = serrno;
 336     return err;
 337 }
 338
 339
 340 static int local_symlink(FsContext *fs_ctx, const char *oldpath,
 341         const char *newpath, FsCred *credp)
 342 {
 343     int err = -1;
 344     int serrno = 0;
 345
 346     /* Determine the security model */
 347     if (fs_ctx->fs_sm == SM_MAPPED) {
 348         int fd;
 349         ssize_t oldpath_size, write_size;
 350         fd = open(rpath(fs_ctx, newpath), O_CREAT|O_EXCL|O_RDWR,
 351                 SM_LOCAL_MODE_BITS);
 352         if (fd == -1) {
 353             return fd;
 354         }
 355         /* Write the oldpath (target) to the file. */
 356         oldpath_size = strlen(oldpath) + 1;
 357         do {
 358             write_size = write(fd, (void *)oldpath, oldpath_size);
 359         } while (write_size == -1 && errno == EINTR);
 360
 361         if (write_size != oldpath_size) {
 362             serrno = errno;
 363             close(fd);
 364             err = -1;
 365             goto err_end;
 366         }
 367         close(fd);
 368         /* Set cleint credentials in symlink's xattr */
 369         credp->fc_mode = credp->fc_mode|S_IFLNK;
 370         err = local_set_xattr(rpath(fs_ctx, newpath), credp);
 371         if (err == -1) {
 372             serrno = errno;
 373             goto err_end;
 374         }
 375     } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
 376         err = symlink(oldpath, rpath(fs_ctx, newpath));
 377         if (err) {
 378             return err;
 379         }
 380         err = lchown(rpath(fs_ctx, newpath), credp->fc_uid, credp->fc_gid);
 381         if (err == -1) {
 382             serrno = errno;
 383             goto err_end;
 384         }
 385     }
 386     return err;
 387
 388 err_end:
 389     remove(rpath(fs_ctx, newpath));
 390     errno = serrno;
 391     return err;
 392 }
 393
 394 static int local_link(FsContext *ctx, const char *oldpath, const char *newpath)
 395 {
 396     char *tmp = qemu_strdup(rpath(ctx, oldpath));
 397     int err, serrno = 0;
 398
 399     if (tmp == NULL) {
 400         return -ENOMEM;
 401     }
 402
 403     err = link(tmp, rpath(ctx, newpath));
 404     if (err == -1) {
 405         serrno = errno;
 406     }
 407
 408     qemu_free(tmp);
 409
 410     if (err == -1) {
 411         errno = serrno;
 412     }
 413
 414     return err;
 415 }
 416
 417 static int local_truncate(FsContext *ctx, const char *path, off_t size)
 418 {
 419     return truncate(rpath(ctx, path), size);
 420 }
 421
 422 static int local_rename(FsContext *ctx, const char *oldpath,
 423                         const char *newpath)
 424 {
 425     char *tmp;
 426     int err;
 427
 428     tmp = qemu_strdup(rpath(ctx, oldpath));
 429
 430     err = rename(tmp, rpath(ctx, newpath));
 431     if (err == -1) {
 432         int serrno = errno;
 433         qemu_free(tmp);
 434         errno = serrno;
 435     } else {
 436         qemu_free(tmp);
 437     }
 438
 439     return err;
 440
 441 }
 442
 443 static int local_chown(FsContext *fs_ctx, const char *path, FsCred *credp)
 444 {
 445     if ((credp->fc_uid == -1 && credp->fc_gid == -1) ||
 446             (fs_ctx->fs_sm == SM_PASSTHROUGH)) {
 447         return lchown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid);
 448     } else if (fs_ctx->fs_sm == SM_MAPPED) {
 449         return local_set_xattr(rpath(fs_ctx, path), credp);
 450     } else if (fs_ctx->fs_sm == SM_PASSTHROUGH) {
 451         return lchown(rpath(fs_ctx, path), credp->fc_uid, credp->fc_gid);
 452     }
 453     return -1;
 454 }
 455
 456 static int local_utimensat(FsContext *s, const char *path,
 457                        const struct timespec *buf)
 458 {
 459     return utimensat(AT_FDCWD, rpath(s, path), buf, AT_SYMLINK_NOFOLLOW);
 460 }
 461
 462 static int local_remove(FsContext *ctx, const char *path)
 463 {
 464     return remove(rpath(ctx, path));
 465 }
 466
 467 static int local_fsync(FsContext *ctx, int fd)
 468 {
 469     return fsync(fd);
 470 }
 471
 472 static int local_statfs(FsContext *s, const char *path, struct statfs *stbuf)
 473 {
 474    return statfs(rpath(s, path), stbuf);
 475 }
 476
 477 static ssize_t local_lgetxattr(FsContext *ctx, const char *path,
 478                                const char *name, void *value, size_t size)
 479 {
 480     if ((ctx->fs_sm == SM_MAPPED) &&
 481         (strncmp(name, "user.virtfs.", 12) == 0)) {
 482         /*
 483          * Don't allow fetch of user.virtfs namesapce
 484          * in case of mapped security
 485          */
 486         errno = ENOATTR;
 487         return -1;
 488     }
 489
 490     return lgetxattr(rpath(ctx, path), name, value, size);
 491 }
 492
 493 static ssize_t local_llistxattr(FsContext *ctx, const char *path,
 494                                 void *value, size_t size)
 495 {
 496     ssize_t retval;
 497     ssize_t actual_len = 0;
 498     char *orig_value, *orig_value_start;
 499     char *temp_value, *temp_value_start;
 500     ssize_t xattr_len, parsed_len = 0, attr_len;
 501
 502     if (ctx->fs_sm != SM_MAPPED) {
 503         return llistxattr(rpath(ctx, path), value, size);
 504     }
 505
 506     /* Get the actual len */
 507     xattr_len = llistxattr(rpath(ctx, path), value, 0);
 508
 509     /* Now fetch the xattr and find the actual size */
 510     orig_value = qemu_malloc(xattr_len);
 511     xattr_len = llistxattr(rpath(ctx, path), orig_value, xattr_len);
 512
 513     /*
 514      * For mapped security model drop user.virtfs namespace
 515      * from the list
 516      */
 517     temp_value = qemu_mallocz(xattr_len);
 518     temp_value_start = temp_value;
 519     orig_value_start = orig_value;
 520     while (xattr_len > parsed_len) {
 521         attr_len = strlen(orig_value) + 1;
 522         if (strncmp(orig_value, "user.virtfs.", 12) != 0) {
 523             /* Copy this entry */
 524             strcat(temp_value, orig_value);
 525             temp_value  += attr_len;
 526             actual_len += attr_len;
 527         }
 528         parsed_len += attr_len;
 529         orig_value += attr_len;
 530     }
 531     if (!size) {
 532         retval = actual_len;
 533         goto out;
 534     } else if (size >= actual_len) {
 535         /* now copy the parsed attribute list back */
 536         memset(value, 0, size);
 537         memcpy(value, temp_value_start, actual_len);
 538         retval = actual_len;
 539         goto out;
 540     }
 541     errno = ERANGE;
 542     retval = -1;
 543 out:
 544     qemu_free(orig_value_start);
 545     qemu_free(temp_value_start);
 546     return retval;
 547 }
 548
 549 static int local_lsetxattr(FsContext *ctx, const char *path, const char *name,
 550                            void *value, size_t size, int flags)
 551 {
 552     if ((ctx->fs_sm == SM_MAPPED) &&
 553         (strncmp(name, "user.virtfs.", 12) == 0)) {
 554         /*
 555          * Don't allow fetch of user.virtfs namesapce
 556          * in case of mapped security
 557          */
 558         errno = EACCES;
 559         return -1;
 560     }
 561     return lsetxattr(rpath(ctx, path), name, value, size, flags);
 562 }
 563
 564 FileOperations local_ops = {
 565     .lstat = local_lstat,
 566     .readlink = local_readlink,
 567     .close = local_close,
 568     .closedir = local_closedir,
 569     .open = local_open,
 570     .opendir = local_opendir,
 571     .rewinddir = local_rewinddir,
 572     .telldir = local_telldir,
 573     .readdir = local_readdir,
 574     .seekdir = local_seekdir,
 575     .readv = local_readv,
 576     .lseek = local_lseek,
 577     .writev = local_writev,
 578     .chmod = local_chmod,
 579     .mknod = local_mknod,
 580     .mkdir = local_mkdir,
 581     .fstat = local_fstat,
 582     .open2 = local_open2,
 583     .symlink = local_symlink,
 584     .link = local_link,
 585     .truncate = local_truncate,
 586     .rename = local_rename,
 587     .chown = local_chown,
 588     .utimensat = local_utimensat,
 589     .remove = local_remove,
 590     .fsync = local_fsync,
 591     .statfs = local_statfs,
 592     .lgetxattr = local_lgetxattr,
 593     .llistxattr = local_llistxattr,
 594     .lsetxattr = local_lsetxattr,
 595 };