fsdev/virtfs-proxy-helper.c

   1 /*
   2  * Helper for QEMU Proxy FS Driver
   3  * Copyright IBM, Corp. 2011
   4  *
   5  * Authors:
   6  * M. Mohan Kumar <mohan@in.ibm.com>
   7  *
   8  * This work is licensed under the terms of the GNU GPL, version 2. See
   9  * the COPYING file in the top-level directory.
  10  */
  11 #include <stdio.h>
  12 #include <sys/socket.h>
  13 #include <string.h>
  14 #include <sys/un.h>
  15 #include <limits.h>
  16 #include <signal.h>
  17 #include <errno.h>
  18 #include <stdlib.h>
  19 #include <sys/resource.h>
  20 #include <sys/stat.h>
  21 #include <getopt.h>
  22 #include <unistd.h>
  23 #include <syslog.h>
  24 #include <sys/capability.h>
  25 #include <sys/fsuid.h>
  26 #include <stdarg.h>
  27 #include <stdbool.h>
  28 #include <sys/vfs.h>
  29 #include <sys/stat.h>
  30 #include <sys/ioctl.h>
  31 #include <linux/fs.h>
  32 #ifdef CONFIG_LINUX_MAGIC_H
  33 #include <linux/magic.h>
  34 #endif
  35 #include "qemu-common.h"
  36 #include "qemu-xattr.h"
  37 #include "virtio-9p-marshal.h"
  38 #include "hw/9pfs/virtio-9p-proxy.h"
  39 #include "fsdev/virtio-9p-marshal.h"
  40
  41 #define PROGNAME "virtfs-proxy-helper"
  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
  56 static struct option helper_opts[] = {
  57     {"fd", required_argument, NULL, 'f'},
  58     {"path", required_argument, NULL, 'p'},
  59     {"nodaemon", no_argument, NULL, 'n'},
  60     {"socket", required_argument, NULL, 's'},
  61     {"uid", required_argument, NULL, 'u'},
  62     {"gid", required_argument, NULL, 'g'},
  63 };
  64
  65 static bool is_daemon;
  66 static bool get_version; /* IOC getversion IOCTL supported */
  67
  68 static void do_log(int loglevel, const char *format, ...)
  69 {
  70     va_list ap;
  71
  72     va_start(ap, format);
  73     if (is_daemon) {
  74         vsyslog(LOG_CRIT, format, ap);
  75     } else {
  76         vfprintf(stderr, format, ap);
  77     }
  78     va_end(ap);
  79 }
  80
  81 static void do_perror(const char *string)
  82 {
  83     if (is_daemon) {
  84         syslog(LOG_CRIT, "%s:%s", string, strerror(errno));
  85     } else {
  86         fprintf(stderr, "%s:%s\n", string, strerror(errno));
  87     }
  88 }
  89
  90 static int do_cap_set(cap_value_t *cap_value, int size, int reset)
  91 {
  92     cap_t caps;
  93     if (reset) {
  94         /*
  95          * Start with an empty set and set permitted and effective
  96          */
  97         caps = cap_init();
  98         if (caps == NULL) {
  99             do_perror("cap_init");
 100             return -1;
 101         }
 102         if (cap_set_flag(caps, CAP_PERMITTED, size, cap_value, CAP_SET) < 0) {
 103             do_perror("cap_set_flag");
 104             goto error;
 105         }
 106     } else {
 107         caps = cap_get_proc();
 108         if (!caps) {
 109             do_perror("cap_get_proc");
 110             return -1;
 111         }
 112     }
 113     if (cap_set_flag(caps, CAP_EFFECTIVE, size, cap_value, CAP_SET) < 0) {
 114         do_perror("cap_set_flag");
 115         goto error;
 116     }
 117     if (cap_set_proc(caps) < 0) {
 118         do_perror("cap_set_proc");
 119         goto error;
 120     }
 121     cap_free(caps);
 122     return 0;
 123
 124 error:
 125     cap_free(caps);
 126     return -1;
 127 }
 128
 129 static int init_capabilities(void)
 130 {
 131     /* helper needs following capbabilities only */
 132     cap_value_t cap_list[] = {
 133         CAP_CHOWN,
 134         CAP_DAC_OVERRIDE,
 135         CAP_FOWNER,
 136         CAP_FSETID,
 137         CAP_SETGID,
 138         CAP_MKNOD,
 139         CAP_SETUID,
 140     };
 141     return do_cap_set(cap_list, ARRAY_SIZE(cap_list), 1);
 142 }
 143
 144 static int socket_read(int sockfd, void *buff, ssize_t size)
 145 {
 146     ssize_t retval, total = 0;
 147
 148     while (size) {
 149         retval = read(sockfd, buff, size);
 150         if (retval == 0) {
 151             return -EIO;
 152         }
 153         if (retval < 0) {
 154             if (errno == EINTR) {
 155                 continue;
 156             }
 157             return -errno;
 158         }
 159         size -= retval;
 160         buff += retval;
 161         total += retval;
 162     }
 163     return total;
 164 }
 165
 166 static int socket_write(int sockfd, void *buff, ssize_t size)
 167 {
 168     ssize_t retval, total = 0;
 169
 170     while (size) {
 171         retval = write(sockfd, buff, size);
 172         if (retval < 0) {
 173             if (errno == EINTR) {
 174                 continue;
 175             }
 176             return -errno;
 177         }
 178         size -= retval;
 179         buff += retval;
 180         total += retval;
 181     }
 182     return total;
 183 }
 184
 185 static int read_request(int sockfd, struct iovec *iovec, ProxyHeader *header)
 186 {
 187     int retval;
 188
 189     /*
 190      * read the request header.
 191      */
 192     iovec->iov_len = 0;
 193     retval = socket_read(sockfd, iovec->iov_base, PROXY_HDR_SZ);
 194     if (retval < 0) {
 195         return retval;
 196     }
 197     iovec->iov_len = PROXY_HDR_SZ;
 198     retval = proxy_unmarshal(iovec, 0, "dd", &header->type, &header->size);
 199     if (retval < 0) {
 200         return retval;
 201     }
 202     /*
 203      * We can't process message.size > PROXY_MAX_IO_SZ.
 204      * Treat it as fatal error
 205      */
 206     if (header->size > PROXY_MAX_IO_SZ) {
 207         return -ENOBUFS;
 208     }
 209     retval = socket_read(sockfd, iovec->iov_base + PROXY_HDR_SZ, header->size);
 210     if (retval < 0) {
 211         return retval;
 212     }
 213     iovec->iov_len += header->size;
 214     return 0;
 215 }
 216
 217 static int send_fd(int sockfd, int fd)
 218 {
 219     struct msghdr msg;
 220     struct iovec iov;
 221     int retval, data;
 222     struct cmsghdr *cmsg;
 223     union MsgControl msg_control;
 224
 225     iov.iov_base = &data;
 226     iov.iov_len = sizeof(data);
 227
 228     memset(&msg, 0, sizeof(msg));
 229     msg.msg_iov = &iov;
 230     msg.msg_iovlen = 1;
 231     /* No ancillary data on error */
 232     if (fd < 0) {
 233         /* fd is really negative errno if the request failed  */
 234         data = fd;
 235     } else {
 236         data = V9FS_FD_VALID;
 237         msg.msg_control = &msg_control;
 238         msg.msg_controllen = sizeof(msg_control);
 239
 240         cmsg = &msg_control.cmsg;
 241         cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
 242         cmsg->cmsg_level = SOL_SOCKET;
 243         cmsg->cmsg_type = SCM_RIGHTS;
 244         memcpy(CMSG_DATA(cmsg), &fd, sizeof(fd));
 245     }
 246
 247     do {
 248         retval = sendmsg(sockfd, &msg, 0);
 249     } while (retval < 0 && errno == EINTR);
 250     if (fd >= 0) {
 251         close(fd);
 252     }
 253     if (retval < 0) {
 254         return retval;
 255     }
 256     return 0;
 257 }
 258
 259 static int send_status(int sockfd, struct iovec *iovec, int status)
 260 {
 261     ProxyHeader header;
 262     int retval, msg_size;;
 263
 264     if (status < 0) {
 265         header.type = T_ERROR;
 266     } else {
 267         header.type = T_SUCCESS;
 268     }
 269     header.size = sizeof(status);
 270     /*
 271      * marshal the return status. We don't check error.
 272      * because we are sure we have enough space for the status
 273      */
 274     msg_size = proxy_marshal(iovec, 0, "ddd", header.type,
 275                              header.size, status);
 276     retval = socket_write(sockfd, iovec->iov_base, msg_size);
 277     if (retval < 0) {
 278         return retval;
 279     }
 280     return 0;
 281 }
 282
 283 /*
 284  * from man 7 capabilities, section
 285  * Effect of User ID Changes on Capabilities:
 286  * 4. If the file system user ID is changed from 0 to nonzero (see setfsuid(2))
 287  * then the following capabilities are cleared from the effective set:
 288  * CAP_CHOWN, CAP_DAC_OVERRIDE, CAP_DAC_READ_SEARCH,  CAP_FOWNER, CAP_FSETID,
 289  * CAP_LINUX_IMMUTABLE  (since  Linux 2.2.30), CAP_MAC_OVERRIDE, and CAP_MKNOD
 290  * (since Linux 2.2.30). If the file system UID is changed from nonzero to 0,
 291  * then any of these capabilities that are enabled in the permitted set
 292  * are enabled in the effective set.
 293  */
 294 static int setfsugid(int uid, int gid)
 295 {
 296     /*
 297      * We still need DAC_OVERRIDE because  we don't change
 298      * supplementary group ids, and hence may be subjected DAC rules
 299      */
 300     cap_value_t cap_list[] = {
 301         CAP_DAC_OVERRIDE,
 302     };
 303
 304     setfsgid(gid);
 305     setfsuid(uid);
 306
 307     if (uid != 0 || gid != 0) {
 308         return do_cap_set(cap_list, ARRAY_SIZE(cap_list), 0);
 309     }
 310     return 0;
 311 }
 312
 313 /*
 314  * send response in two parts
 315  * 1) ProxyHeader
 316  * 2) Response or error status
 317  * This function should be called with marshaled response
 318  * send_response constructs header part and error part only.
 319  * send response sends {ProxyHeader,Response} if the request was success
 320  * otherwise sends {ProxyHeader,error status}
 321  */
 322 static int send_response(int sock, struct iovec *iovec, int size)
 323 {
 324     int retval;
 325     ProxyHeader header;
 326
 327     /*
 328      * If response size exceeds available iovec->iov_len,
 329      * we return ENOBUFS
 330      */
 331     if (size > PROXY_MAX_IO_SZ) {
 332         size = -ENOBUFS;
 333     }
 334
 335     if (size < 0) {
 336         /*
 337          * In case of error we would not have got the error encoded
 338          * already so encode the error here.
 339          */
 340         header.type = T_ERROR;
 341         header.size = sizeof(size);
 342         proxy_marshal(iovec, PROXY_HDR_SZ, "d", size);
 343     } else {
 344         header.type = T_SUCCESS;
 345         header.size = size;
 346     }
 347     proxy_marshal(iovec, 0, "dd", header.type, header.size);
 348     retval = socket_write(sock, iovec->iov_base, header.size + PROXY_HDR_SZ);
 349     if (retval < 0) {
 350         return retval;;
 351     }
 352     return 0;
 353 }
 354
 355 /*
 356  * gets generation number
 357  * returns -errno on failure and sizeof(generation number) on success
 358  */
 359 static int do_getversion(struct iovec *iovec, struct iovec *out_iovec)
 360 {
 361     uint64_t version;
 362     int retval = -ENOTTY;
 363 #ifdef FS_IOC_GETVERSION
 364     int fd;
 365     V9fsString path;
 366 #endif
 367
 368
 369     /* no need to issue ioctl */
 370     if (!get_version) {
 371         version = 0;
 372         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version);
 373         return retval;
 374     }
 375 #ifdef FS_IOC_GETVERSION
 376     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "s", &path);
 377     if (retval < 0) {
 378         return retval;
 379     }
 380
 381     fd = open(path.data, O_RDONLY);
 382     if (fd < 0) {
 383         retval = -errno;
 384         goto err_out;
 385     }
 386     if (ioctl(fd, FS_IOC_GETVERSION, &version) < 0) {
 387         retval = -errno;
 388     } else {
 389         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "q", version);
 390     }
 391     close(fd);
 392 err_out:
 393     v9fs_string_free(&path);
 394 #endif
 395     return retval;
 396 }
 397
 398 static int do_getxattr(int type, struct iovec *iovec, struct iovec *out_iovec)
 399 {
 400     int size = 0, offset, retval;
 401     V9fsString path, name, xattr;
 402
 403     v9fs_string_init(&xattr);
 404     v9fs_string_init(&path);
 405     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "ds", &size, &path);
 406     if (retval < 0) {
 407         return retval;
 408     }
 409     offset = PROXY_HDR_SZ + retval;
 410
 411     if (size) {
 412         xattr.data = g_malloc(size);
 413         xattr.size = size;
 414     }
 415     switch (type) {
 416     case T_LGETXATTR:
 417         v9fs_string_init(&name);
 418         retval = proxy_unmarshal(iovec, offset, "s", &name);
 419         if (retval > 0) {
 420             retval = lgetxattr(path.data, name.data, xattr.data, size);
 421             if (retval < 0) {
 422                 retval = -errno;
 423             } else {
 424                 xattr.size = retval;
 425             }
 426         }
 427         v9fs_string_free(&name);
 428         break;
 429     case T_LLISTXATTR:
 430         retval = llistxattr(path.data, xattr.data, size);
 431         if (retval < 0) {
 432             retval = -errno;
 433         } else {
 434             xattr.size = retval;
 435         }
 436         break;
 437     }
 438     if (retval < 0) {
 439         goto err_out;
 440     }
 441
 442     if (!size) {
 443         proxy_marshal(out_iovec, PROXY_HDR_SZ, "d", retval);
 444         retval = sizeof(retval);
 445     } else {
 446         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "s", &xattr);
 447     }
 448 err_out:
 449     v9fs_string_free(&xattr);
 450     v9fs_string_free(&path);
 451     return retval;
 452 }
 453
 454 static void stat_to_prstat(ProxyStat *pr_stat, struct stat *stat)
 455 {
 456     memset(pr_stat, 0, sizeof(*pr_stat));
 457     pr_stat->st_dev = stat->st_dev;
 458     pr_stat->st_ino = stat->st_ino;
 459     pr_stat->st_nlink = stat->st_nlink;
 460     pr_stat->st_mode = stat->st_mode;
 461     pr_stat->st_uid = stat->st_uid;
 462     pr_stat->st_gid = stat->st_gid;
 463     pr_stat->st_rdev = stat->st_rdev;
 464     pr_stat->st_size = stat->st_size;
 465     pr_stat->st_blksize = stat->st_blksize;
 466     pr_stat->st_blocks = stat->st_blocks;
 467     pr_stat->st_atim_sec = stat->st_atim.tv_sec;
 468     pr_stat->st_atim_nsec = stat->st_atim.tv_nsec;
 469     pr_stat->st_mtim_sec = stat->st_mtim.tv_sec;
 470     pr_stat->st_mtim_nsec = stat->st_mtim.tv_nsec;
 471     pr_stat->st_ctim_sec = stat->st_ctim.tv_sec;
 472     pr_stat->st_ctim_nsec = stat->st_ctim.tv_nsec;
 473 }
 474
 475 static void statfs_to_prstatfs(ProxyStatFS *pr_stfs, struct statfs *stfs)
 476 {
 477     memset(pr_stfs, 0, sizeof(*pr_stfs));
 478     pr_stfs->f_type = stfs->f_type;
 479     pr_stfs->f_bsize = stfs->f_bsize;
 480     pr_stfs->f_blocks = stfs->f_blocks;
 481     pr_stfs->f_bfree = stfs->f_bfree;
 482     pr_stfs->f_bavail = stfs->f_bavail;
 483     pr_stfs->f_files = stfs->f_files;
 484     pr_stfs->f_ffree = stfs->f_ffree;
 485     pr_stfs->f_fsid[0] = stfs->f_fsid.__val[0];
 486     pr_stfs->f_fsid[1] = stfs->f_fsid.__val[1];
 487     pr_stfs->f_namelen = stfs->f_namelen;
 488     pr_stfs->f_frsize = stfs->f_frsize;
 489 }
 490
 491 /*
 492  * Gets stat/statfs information and packs in out_iovec structure
 493  * on success returns number of bytes packed in out_iovec struture
 494  * otherwise returns -errno
 495  */
 496 static int do_stat(int type, struct iovec *iovec, struct iovec *out_iovec)
 497 {
 498     int retval;
 499     V9fsString path;
 500     ProxyStat pr_stat;
 501     ProxyStatFS pr_stfs;
 502     struct stat st_buf;
 503     struct statfs stfs_buf;
 504
 505     v9fs_string_init(&path);
 506     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "s", &path);
 507     if (retval < 0) {
 508         return retval;
 509     }
 510
 511     switch (type) {
 512     case T_LSTAT:
 513         retval = lstat(path.data, &st_buf);
 514         if (retval < 0) {
 515             retval = -errno;
 516         } else {
 517             stat_to_prstat(&pr_stat, &st_buf);
 518             retval = proxy_marshal(out_iovec, PROXY_HDR_SZ,
 519                                    "qqqdddqqqqqqqqqq", pr_stat.st_dev,
 520                                    pr_stat.st_ino, pr_stat.st_nlink,
 521                                    pr_stat.st_mode, pr_stat.st_uid,
 522                                    pr_stat.st_gid, pr_stat.st_rdev,
 523                                    pr_stat.st_size, pr_stat.st_blksize,
 524                                    pr_stat.st_blocks,
 525                                    pr_stat.st_atim_sec, pr_stat.st_atim_nsec,
 526                                    pr_stat.st_mtim_sec, pr_stat.st_mtim_nsec,
 527                                    pr_stat.st_ctim_sec, pr_stat.st_ctim_nsec);
 528         }
 529         break;
 530     case T_STATFS:
 531         retval = statfs(path.data, &stfs_buf);
 532         if (retval < 0) {
 533             retval = -errno;
 534         } else {
 535             statfs_to_prstatfs(&pr_stfs, &stfs_buf);
 536             retval = proxy_marshal(out_iovec, PROXY_HDR_SZ,
 537                                    "qqqqqqqqqqq", pr_stfs.f_type,
 538                                    pr_stfs.f_bsize, pr_stfs.f_blocks,
 539                                    pr_stfs.f_bfree, pr_stfs.f_bavail,
 540                                    pr_stfs.f_files, pr_stfs.f_ffree,
 541                                    pr_stfs.f_fsid[0], pr_stfs.f_fsid[1],
 542                                    pr_stfs.f_namelen, pr_stfs.f_frsize);
 543         }
 544         break;
 545     }
 546     v9fs_string_free(&path);
 547     return retval;
 548 }
 549
 550 static int do_readlink(struct iovec *iovec, struct iovec *out_iovec)
 551 {
 552     char *buffer;
 553     int size, retval;
 554     V9fsString target, path;
 555
 556     v9fs_string_init(&path);
 557     retval = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sd", &path, &size);
 558     if (retval < 0) {
 559         v9fs_string_free(&path);
 560         return retval;
 561     }
 562     buffer = g_malloc(size);
 563     v9fs_string_init(&target);
 564     retval = readlink(path.data, buffer, size);
 565     if (retval > 0) {
 566         buffer[retval] = '\0';
 567         v9fs_string_sprintf(&target, "%s", buffer);
 568         retval = proxy_marshal(out_iovec, PROXY_HDR_SZ, "s", &target);
 569     } else {
 570         retval = -errno;
 571     }
 572     g_free(buffer);
 573     v9fs_string_free(&target);
 574     v9fs_string_free(&path);
 575     return retval;
 576 }
 577
 578 /*
 579  * create other filesystem objects and send 0 on success
 580  * return -errno on error
 581  */
 582 static int do_create_others(int type, struct iovec *iovec)
 583 {
 584     dev_t rdev;
 585     int retval = 0;
 586     int offset = PROXY_HDR_SZ;
 587     V9fsString oldpath, path;
 588     int mode, uid, gid, cur_uid, cur_gid;
 589
 590     v9fs_string_init(&path);
 591     v9fs_string_init(&oldpath);
 592     cur_uid = geteuid();
 593     cur_gid = getegid();
 594
 595     retval = proxy_unmarshal(iovec, offset, "dd", &uid, &gid);
 596     if (retval < 0) {
 597         return retval;
 598     }
 599     offset += retval;
 600     retval = setfsugid(uid, gid);
 601     if (retval < 0) {
 602         retval = -errno;
 603         goto err_out;
 604     }
 605     switch (type) {
 606     case T_MKNOD:
 607         retval = proxy_unmarshal(iovec, offset, "sdq", &path, &mode, &rdev);
 608         if (retval < 0) {
 609             goto err_out;
 610         }
 611         retval = mknod(path.data, mode, rdev);
 612         break;
 613     case T_MKDIR:
 614         retval = proxy_unmarshal(iovec, offset, "sd", &path, &mode);
 615         if (retval < 0) {
 616             goto err_out;
 617         }
 618         retval = mkdir(path.data, mode);
 619         break;
 620     case T_SYMLINK:
 621         retval = proxy_unmarshal(iovec, offset, "ss", &oldpath, &path);
 622         if (retval < 0) {
 623             goto err_out;
 624         }
 625         retval = symlink(oldpath.data, path.data);
 626         break;
 627     }
 628     if (retval < 0) {
 629         retval = -errno;
 630     }
 631
 632 err_out:
 633     v9fs_string_free(&path);
 634     v9fs_string_free(&oldpath);
 635     setfsugid(cur_uid, cur_gid);
 636     return retval;
 637 }
 638
 639 /*
 640  * create a file and send fd on success
 641  * return -errno on error
 642  */
 643 static int do_create(struct iovec *iovec)
 644 {
 645     int ret;
 646     V9fsString path;
 647     int flags, mode, uid, gid, cur_uid, cur_gid;
 648
 649     v9fs_string_init(&path);
 650     ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sdddd",
 651                           &path, &flags, &mode, &uid, &gid);
 652     if (ret < 0) {
 653         goto unmarshal_err_out;
 654     }
 655     cur_uid = geteuid();
 656     cur_gid = getegid();
 657     ret = setfsugid(uid, gid);
 658     if (ret < 0) {
 659         /*
 660          * On failure reset back to the
 661          * old uid/gid
 662          */
 663         ret = -errno;
 664         goto err_out;
 665     }
 666     ret = open(path.data, flags, mode);
 667     if (ret < 0) {
 668         ret = -errno;
 669     }
 670
 671 err_out:
 672     setfsugid(cur_uid, cur_gid);
 673 unmarshal_err_out:
 674     v9fs_string_free(&path);
 675     return ret;
 676 }
 677
 678 /*
 679  * open a file and send fd on success
 680  * return -errno on error
 681  */
 682 static int do_open(struct iovec *iovec)
 683 {
 684     int flags, ret;
 685     V9fsString path;
 686
 687     v9fs_string_init(&path);
 688     ret = proxy_unmarshal(iovec, PROXY_HDR_SZ, "sd", &path, &flags);
 689     if (ret < 0) {
 690         goto err_out;
 691     }
 692     ret = open(path.data, flags);
 693     if (ret < 0) {
 694         ret = -errno;
 695     }
 696 err_out:
 697     v9fs_string_free(&path);
 698     return ret;
 699 }
 700
 701 /* create unix domain socket and return the descriptor */
 702 static int proxy_socket(const char *path, uid_t uid, gid_t gid)
 703 {
 704     int sock, client;
 705     struct sockaddr_un proxy, qemu;
 706     socklen_t size;
 707
 708     /* requested socket already exists, refuse to start */
 709     if (!access(path, F_OK)) {
 710         do_log(LOG_CRIT, "socket already exists\n");
 711         return -1;
 712     }
 713
 714     sock = socket(AF_UNIX, SOCK_STREAM, 0);
 715     if (sock < 0) {
 716         do_perror("socket");
 717         return -1;
 718     }
 719
 720     /* mask other part of mode bits */
 721     umask(7);
 722
 723     proxy.sun_family = AF_UNIX;
 724     strcpy(proxy.sun_path, path);
 725     if (bind(sock, (struct sockaddr *)&proxy,
 726             sizeof(struct sockaddr_un)) < 0) {
 727         do_perror("bind");
 728         return -1;
 729     }
 730     if (chown(proxy.sun_path, uid, gid) < 0) {
 731         do_perror("chown");
 732         return -1;
 733     }
 734     if (listen(sock, 1) < 0) {
 735         do_perror("listen");
 736         return -1;
 737     }
 738
 739     client = accept(sock, (struct sockaddr *)&qemu, &size);
 740     if (client < 0) {
 741         do_perror("accept");
 742         return -1;
 743     }
 744     return client;
 745 }
 746
 747 static void usage(char *prog)
 748 {
 749     fprintf(stderr, "usage: %s\n"
 750             " -p|--path <path> 9p path to export\n"
 751             " {-f|--fd <socket-descriptor>} socket file descriptor to be used\n"
 752             " {-s|--socket <socketname> socket file used for communication\n"
 753             " \t-u|--uid <uid> -g|--gid <gid>} - uid:gid combination to give "
 754             " access to this socket\n"
 755             " \tNote: -s & -f can not be used together\n"
 756             " [-n|--nodaemon] Run as a normal program\n",
 757             basename(prog));
 758 }
 759
 760 static int process_reply(int sock, int type,
 761                          struct iovec *out_iovec, int retval)
 762 {
 763     switch (type) {
 764     case T_OPEN:
 765     case T_CREATE:
 766         if (send_fd(sock, retval) < 0) {
 767             return -1;
 768         }
 769         break;
 770     case T_MKNOD:
 771     case T_MKDIR:
 772     case T_SYMLINK:
 773     case T_LINK:
 774     case T_CHMOD:
 775     case T_CHOWN:
 776     case T_TRUNCATE:
 777     case T_UTIME:
 778     case T_RENAME:
 779     case T_REMOVE:
 780     case T_LSETXATTR:
 781     case T_LREMOVEXATTR:
 782         if (send_status(sock, out_iovec, retval) < 0) {
 783             return -1;
 784         }
 785         break;
 786     case T_LSTAT:
 787     case T_STATFS:
 788     case T_READLINK:
 789     case T_LGETXATTR:
 790     case T_LLISTXATTR:
 791     case T_GETVERSION:
 792         if (send_response(sock, out_iovec, retval) < 0) {
 793             return -1;
 794         }
 795         break;
 796     default:
 797         return -1;
 798         break;
 799     }
 800     return 0;
 801 }
 802
 803 static int process_requests(int sock)
 804 {
 805     int flags;
 806     int size = 0;
 807     int retval = 0;
 808     uint64_t offset;
 809     ProxyHeader header;
 810     int mode, uid, gid;
 811     V9fsString name, value;
 812     struct timespec spec[2];
 813     V9fsString oldpath, path;
 814     struct iovec in_iovec, out_iovec;
 815
 816     in_iovec.iov_base  = g_malloc(PROXY_MAX_IO_SZ + PROXY_HDR_SZ);
 817     in_iovec.iov_len   = PROXY_MAX_IO_SZ + PROXY_HDR_SZ;
 818     out_iovec.iov_base = g_malloc(PROXY_MAX_IO_SZ + PROXY_HDR_SZ);
 819     out_iovec.iov_len  = PROXY_MAX_IO_SZ + PROXY_HDR_SZ;
 820
 821     while (1) {
 822         /*
 823          * initialize the header type, so that we send
 824          * response to proper request type.
 825          */
 826         header.type = 0;
 827         retval = read_request(sock, &in_iovec, &header);
 828         if (retval < 0) {
 829             goto err_out;
 830         }
 831
 832         switch (header.type) {
 833         case T_OPEN:
 834             retval = do_open(&in_iovec);
 835             break;
 836         case T_CREATE:
 837             retval = do_create(&in_iovec);
 838             break;
 839         case T_MKNOD:
 840         case T_MKDIR:
 841         case T_SYMLINK:
 842             retval = do_create_others(header.type, &in_iovec);
 843             break;
 844         case T_LINK:
 845             v9fs_string_init(&path);
 846             v9fs_string_init(&oldpath);
 847             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
 848                                      "ss", &oldpath, &path);
 849             if (retval > 0) {
 850                 retval = link(oldpath.data, path.data);
 851                 if (retval < 0) {
 852                     retval = -errno;
 853                 }
 854             }
 855             v9fs_string_free(&oldpath);
 856             v9fs_string_free(&path);
 857             break;
 858         case T_LSTAT:
 859         case T_STATFS:
 860             retval = do_stat(header.type, &in_iovec, &out_iovec);
 861             break;
 862         case T_READLINK:
 863             retval = do_readlink(&in_iovec, &out_iovec);
 864             break;
 865         case T_CHMOD:
 866             v9fs_string_init(&path);
 867             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
 868                                      "sd", &path, &mode);
 869             if (retval > 0) {
 870                 retval = chmod(path.data, mode);
 871                 if (retval < 0) {
 872                     retval = -errno;
 873                 }
 874             }
 875             v9fs_string_free(&path);
 876             break;
 877         case T_CHOWN:
 878             v9fs_string_init(&path);
 879             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sdd", &path,
 880                                      &uid, &gid);
 881             if (retval > 0) {
 882                 retval = lchown(path.data, uid, gid);
 883                 if (retval < 0) {
 884                     retval = -errno;
 885                 }
 886             }
 887             v9fs_string_free(&path);
 888             break;
 889         case T_TRUNCATE:
 890             v9fs_string_init(&path);
 891             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sq",
 892                                      &path, &offset);
 893             if (retval > 0) {
 894                 retval = truncate(path.data, offset);
 895                 if (retval < 0) {
 896                     retval = -errno;
 897                 }
 898             }
 899             v9fs_string_free(&path);
 900             break;
 901         case T_UTIME:
 902             v9fs_string_init(&path);
 903             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sqqqq", &path,
 904                                      &spec[0].tv_sec, &spec[0].tv_nsec,
 905                                      &spec[1].tv_sec, &spec[1].tv_nsec);
 906             if (retval > 0) {
 907                 retval = qemu_utimens(path.data, spec);
 908                 if (retval < 0) {
 909                     retval = -errno;
 910                 }
 911             }
 912             v9fs_string_free(&path);
 913             break;
 914         case T_RENAME:
 915             v9fs_string_init(&path);
 916             v9fs_string_init(&oldpath);
 917             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ,
 918                                      "ss", &oldpath, &path);
 919             if (retval > 0) {
 920                 retval = rename(oldpath.data, path.data);
 921                 if (retval < 0) {
 922                     retval = -errno;
 923                 }
 924             }
 925             v9fs_string_free(&oldpath);
 926             v9fs_string_free(&path);
 927             break;
 928         case T_REMOVE:
 929             v9fs_string_init(&path);
 930             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "s", &path);
 931             if (retval > 0) {
 932                 retval = remove(path.data);
 933                 if (retval < 0) {
 934                     retval = -errno;
 935                 }
 936             }
 937             v9fs_string_free(&path);
 938             break;
 939         case T_LGETXATTR:
 940         case T_LLISTXATTR:
 941             retval = do_getxattr(header.type, &in_iovec, &out_iovec);
 942             break;
 943         case T_LSETXATTR:
 944             v9fs_string_init(&path);
 945             v9fs_string_init(&name);
 946             v9fs_string_init(&value);
 947             retval = proxy_unmarshal(&in_iovec, PROXY_HDR_SZ, "sssdd", &path,
 948                                      &name, &value, &size, &flags);
 949             if (retval > 0) {
 950                 retval = lsetxattr(path.data,
 951                                    name.data, value.data, size, flags);
 952                 if (retval < 0) {
 953                     retval = -errno;
 954                 }
 955             }
 956             v9fs_string_free(&path);
 957             v9fs_string_free(&name);
 958             v9fs_string_free(&value);
 959             break;
 960         case T_LREMOVEXATTR:
 961             v9fs_string_init(&path);
 962             v9fs_string_init(&name);
 963             retval = proxy_unmarshal(&in_iovec,
 964                                      PROXY_HDR_SZ, "ss", &path, &name);
 965             if (retval > 0) {
 966                 retval = lremovexattr(path.data, name.data);
 967                 if (retval < 0) {
 968                     retval = -errno;
 969                 }
 970             }
 971             v9fs_string_free(&path);
 972             v9fs_string_free(&name);
 973             break;
 974         case T_GETVERSION:
 975             retval = do_getversion(&in_iovec, &out_iovec);
 976             break;
 977         default:
 978             goto err_out;
 979             break;
 980         }
 981
 982         if (process_reply(sock, header.type, &out_iovec, retval) < 0) {
 983             goto err_out;
 984         }
 985     }
 986 err_out:
 987     g_free(in_iovec.iov_base);
 988     g_free(out_iovec.iov_base);
 989     return -1;
 990 }
 991
 992 int main(int argc, char **argv)
 993 {
 994     int sock;
 995     uid_t own_u;
 996     gid_t own_g;
 997     char *rpath = NULL;
 998     char *sock_name = NULL;
 999     struct stat stbuf;
1000     int c, option_index;
1001 #ifdef FS_IOC_GETVERSION
1002     int retval;
1003     struct statfs st_fs;
1004 #endif
1005
1006     is_daemon = true;
1007     sock = -1;
1008     own_u = own_g = -1;
1009     while (1) {
1010         option_index = 0;
1011         c = getopt_long(argc, argv, "p:nh?f:s:u:g:", helper_opts,
1012                         &option_index);
1013         if (c == -1) {
1014             break;
1015         }
1016         switch (c) {
1017         case 'p':
1018             rpath = strdup(optarg);
1019             break;
1020         case 'n':
1021             is_daemon = false;
1022             break;
1023         case 'f':
1024             sock = atoi(optarg);
1025             break;
1026         case 's':
1027             sock_name = strdup(optarg);
1028             break;
1029         case 'u':
1030             own_u = atoi(optarg);
1031             break;
1032         case 'g':
1033             own_g = atoi(optarg);
1034             break;
1035         case '?':
1036         case 'h':
1037         default:
1038             usage(argv[0]);
1039             exit(EXIT_FAILURE);
1040         }
1041     }
1042
1043     /* Parameter validation */
1044     if ((sock_name == NULL && sock == -1) || rpath == NULL) {
1045         fprintf(stderr, "socket, socket descriptor or path not specified\n");
1046         usage(argv[0]);
1047         return -1;
1048     }
1049
1050     if (*sock_name && (own_u == -1 || own_g == -1)) {
1051         fprintf(stderr, "owner uid:gid not specified, ");
1052         fprintf(stderr,
1053                 "owner uid:gid specifies who can access the socket file\n");
1054         usage(argv[0]);
1055         exit(EXIT_FAILURE);
1056     }
1057
1058     if (lstat(rpath, &stbuf) < 0) {
1059         fprintf(stderr, "invalid path \"%s\" specified, %s\n",
1060                 rpath, strerror(errno));
1061         exit(EXIT_FAILURE);
1062     }
1063
1064     if (!S_ISDIR(stbuf.st_mode)) {
1065         fprintf(stderr, "specified path \"%s\" is not directory\n", rpath);
1066         exit(EXIT_FAILURE);
1067     }
1068
1069     if (is_daemon) {
1070         if (daemon(0, 0) < 0) {
1071             fprintf(stderr, "daemon call failed\n");
1072             exit(EXIT_FAILURE);
1073         }
1074         openlog(PROGNAME, LOG_PID, LOG_DAEMON);
1075     }
1076
1077     do_log(LOG_INFO, "Started\n");
1078     if (*sock_name) {
1079         sock = proxy_socket(sock_name, own_u, own_g);
1080         if (sock < 0) {
1081             goto error;
1082         }
1083     }
1084
1085     get_version = false;
1086 #ifdef FS_IOC_GETVERSION
1087     /* check whether underlying FS support IOC_GETVERSION */
1088     retval = statfs(rpath, &st_fs);
1089     if (!retval) {
1090         switch (st_fs.f_type) {
1091         case EXT2_SUPER_MAGIC:
1092         case BTRFS_SUPER_MAGIC:
1093         case REISERFS_SUPER_MAGIC:
1094         case XFS_SUPER_MAGIC:
1095             get_version = true;
1096             break;
1097         }
1098     }
1099 #endif
1100
1101     if (chdir("/") < 0) {
1102         do_perror("chdir");
1103         goto error;
1104     }
1105     if (chroot(rpath) < 0) {
1106         do_perror("chroot");
1107         goto error;
1108     }
1109     umask(0);
1110
1111     if (init_capabilities() < 0) {
1112         goto error;
1113     }
1114
1115     process_requests(sock);
1116 error:
1117     do_log(LOG_INFO, "Done\n");
1118     closelog();
1119     return 0;
1120 }