client/umount.cifs.c

   1 /*
   2    Unmount utility program for Linux CIFS VFS (virtual filesystem) client
   3    Copyright (C) 2005 Steve French  (sfrench@us.ibm.com)
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _GNU_SOURCE
  19 #define _GNU_SOURCE
  20 #endif
  21
  22 #include <stdlib.h>
  23 #include <stdio.h>
  24 #include <unistd.h>
  25 #include <ctype.h>
  26 #include <sys/types.h>
  27 #include <sys/mount.h>
  28 #include <sys/ioctl.h>
  29 #include <sys/stat.h>
  30 #include <sys/vfs.h>
  31 #include <fcntl.h>
  32 #include <getopt.h>
  33 #include <errno.h>
  34 #include <string.h>
  35 #include <mntent.h>
  36 #include <limits.h>
  37 #include "mount.h"
  38
  39 #define UNMOUNT_CIFS_VERSION_MAJOR "0"
  40 #define UNMOUNT_CIFS_VERSION_MINOR "6"
  41
  42 #ifndef UNMOUNT_CIFS_VENDOR_SUFFIX
  43  #ifdef _SAMBA_BUILD_
  44   #include "version.h"
  45   #ifdef SAMBA_VERSION_VENDOR_SUFFIX
  46    #define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING"-"SAMBA_VERSION_VENDOR_SUFFIX
  47   #else
  48    #define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING
  49   #endif /* SAMBA_VERSION_OFFICIAL_STRING and SAMBA_VERSION_VENDOR_SUFFIX */
  50  #else
  51   #define UNMOUNT_CIFS_VENDOR_SUFFIX ""
  52  #endif /* _SAMBA_BUILD_ */
  53 #endif /* UNMOUNT_CIFS_VENDOR_SUFFIX */
  54
  55 #ifndef MNT_DETACH
  56 #define MNT_DETACH 0x02
  57 #endif
  58
  59 #ifndef MNT_EXPIRE
  60 #define MNT_EXPIRE 0x04
  61 #endif
  62
  63 #ifndef MOUNTED_LOCK
  64 #define MOUNTED_LOCK    "/etc/mtab~"
  65 #endif
  66 #ifndef MOUNTED_TEMP
  67 #define MOUNTED_TEMP    "/etc/mtab.tmp"
  68 #endif
  69
  70 #define CIFS_IOC_CHECKUMOUNT _IO(0xCF, 2)
  71 #define CIFS_MAGIC_NUMBER 0xFF534D42   /* the first four bytes of SMB PDU */
  72
  73 static struct option longopts[] = {
  74         { "all", 0, NULL, 'a' },
  75         { "help",0, NULL, 'h' },
  76         { "read-only", 0, NULL, 'r' },
  77         { "ro", 0, NULL, 'r' },
  78         { "verbose", 0, NULL, 'v' },
  79         { "version", 0, NULL, 'V' },
  80         { "expire", 0, NULL, 'e' },
  81         { "force", 0, 0, 'f' },
  82         { "lazy", 0, 0, 'l' },
  83         { "no-mtab", 0, 0, 'n' },
  84         { NULL, 0, NULL, 0 }
  85 };
  86
  87 const char * thisprogram;
  88 int verboseflg = 0;
  89
  90 static void umount_cifs_usage(void)
  91 {
  92         printf("\nUsage:  %s <remotetarget> <dir>\n", thisprogram);
  93         printf("\nUnmount the specified directory\n");
  94         printf("\nLess commonly used options:");
  95         printf("\n\t-r\tIf mount fails, retry with readonly remount.");
  96         printf("\n\t-n\tDo not write to mtab.");
  97         printf("\n\t-f\tAttempt a forced unmount, even if the fs is busy.");
  98         printf("\n\t-l\tAttempt lazy unmount, Unmount now, cleanup later.");
  99         printf("\n\t-v\tEnable verbose mode (may be useful for debugging).");
 100         printf("\n\t-h\tDisplay this help.");
 101         printf("\n\nOptions are described in more detail in the manual page");
 102         printf("\n\tman 8 umount.cifs\n");
 103         printf("\nTo display the version number of the cifs umount utility:");
 104         printf("\n\t%s -V\n",thisprogram);
 105         printf("\nInvoking the umount utility on cifs mounts, can execute");
 106         printf(" /sbin/umount.cifs (if present and umount -i is not specified.\n");
 107 }
 108
 109 static int umount_check_perm(char * dir)
 110 {
 111         int fileid;
 112         int rc;
 113
 114         /* allow root to unmount, no matter what */
 115         if(getuid() == 0)
 116                 return 0;
 117
 118         /* presumably can not chdir into the target as we do on mount */
 119         fileid = open(dir, O_RDONLY | O_DIRECTORY | O_NOFOLLOW, 0);
 120         if(fileid == -1) {
 121                 if(verboseflg)
 122                         printf("error opening mountpoint %d %s",errno,strerror(errno));
 123                 return errno;
 124         }
 125
 126         rc = ioctl(fileid, CIFS_IOC_CHECKUMOUNT, NULL);
 127
 128         if(verboseflg)
 129                 printf("ioctl returned %d with errno %d %s\n",rc,errno,strerror(errno));
 130
 131         if(rc == ENOTTY) {
 132                 printf("user unmounting via %s is an optional feature of",thisprogram);
 133                 printf(" the cifs filesystem driver (cifs.ko)");
 134                 printf("\n\tand requires cifs.ko version 1.32 or later\n");
 135         } else if (rc != 0)
 136                 printf("user unmount of %s failed with %d %s\n",dir,errno,strerror(errno));
 137         close(fileid);
 138
 139         return rc;
 140 }
 141
 142 static int remove_from_mtab(char * mountpoint)
 143 {
 144         int rc;
 145         int num_matches;
 146         FILE * org_fd;
 147         FILE * new_fd;
 148         struct mntent * mount_entry;
 149         struct stat statbuf;
 150
 151         /* If it is a symlink, e.g. to /proc/mounts, no need to update it. */
 152         if ((lstat(MOUNTED, &statbuf) == 0) && (S_ISLNK(statbuf.st_mode)))
 153                 return 0;
 154
 155         /* Do we first need to check if it is writable? */
 156
 157         atexit(unlock_mtab);
 158         if (lock_mtab()) {
 159                 printf("Mount table locked\n");
 160                 return -EACCES;
 161         }
 162
 163         if(verboseflg)
 164                 printf("attempting to remove from mtab\n");
 165
 166         org_fd = setmntent(MOUNTED, "r");
 167         if(org_fd == NULL) {
 168                 printf("Can not open %s\n",MOUNTED);
 169                 unlock_mtab();
 170                 return -EIO;
 171         }
 172
 173         new_fd = setmntent(MOUNTED_TEMP,"w");
 174         if(new_fd == NULL) {
 175                 printf("Can not open temp file %s", MOUNTED_TEMP);
 176                 endmntent(org_fd);
 177                 unlock_mtab();
 178                 return -EIO;
 179         }
 180
 181         /* BB fix so we only remove the last entry that matches BB */
 182         num_matches = 0;
 183         while((mount_entry = getmntent(org_fd)) != NULL) {
 184                 if(strcmp(mount_entry->mnt_dir, mountpoint) == 0) {
 185                         num_matches++;
 186                 }
 187         }
 188         if(verboseflg)
 189                 printf("%d matching entries in mount table\n", num_matches);
 190
 191         /* Is there a better way to seek back to the first entry in mtab? */
 192         endmntent(org_fd);
 193         org_fd = setmntent(MOUNTED, "r");
 194
 195         if(org_fd == NULL) {
 196                 printf("Can not open %s\n",MOUNTED);
 197                 unlock_mtab();
 198                 return -EIO;
 199         }
 200
 201         while((mount_entry = getmntent(org_fd)) != NULL) {
 202                 if(strcmp(mount_entry->mnt_dir, mountpoint) != 0) {
 203                         addmntent(new_fd, mount_entry);
 204                 } else {
 205                         if(num_matches != 1) {
 206                                 addmntent(new_fd, mount_entry);
 207                                 num_matches--;
 208                         } else if(verboseflg)
 209                                 printf("entry not copied (ie entry is removed)\n");
 210                 }
 211         }
 212
 213         if(verboseflg)
 214                 printf("done updating tmp file\n");
 215         rc = fchmod (fileno (new_fd), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
 216         if(rc < 0) {
 217                 printf("error %s changing mode of %s\n", strerror(errno),
 218                         MOUNTED_TEMP);
 219         }
 220         endmntent(new_fd);
 221
 222         rc = rename(MOUNTED_TEMP, MOUNTED);
 223
 224         if(rc < 0) {
 225                 printf("failure %s renaming %s to %s\n",strerror(errno),
 226                         MOUNTED_TEMP, MOUNTED);
 227                 unlock_mtab();
 228                 return -EIO;
 229         }
 230
 231         unlock_mtab();
 232
 233         return rc;
 234 }
 235
 236 /* Make a canonical pathname from PATH.  Returns a freshly malloced string.
 237    It is up the *caller* to ensure that the PATH is sensible.  i.e.
 238    canonicalize ("/dev/fd0/.") returns "/dev/fd0" even though ``/dev/fd0/.''
 239    is not a legal pathname for ``/dev/fd0''  Anything we cannot parse
 240    we return unmodified.   */
 241 static char *
 242 canonicalize(char *path)
 243 {
 244         char *canonical;
 245
 246         if (path == NULL) {
 247                 return NULL;
 248         }
 249
 250         if (strlen(path) > PATH_MAX) {
 251                 fprintf(stderr, "Mount point string too long\n");
 252                 return NULL;
 253         }
 254
 255         canonical = (char *)malloc (PATH_MAX + 1);
 256
 257         if (!canonical) {
 258                 fprintf(stderr, "Error! Not enough memory!\n");
 259                 return NULL;
 260         }
 261
 262         if (realpath (path, canonical))
 263                 return canonical;
 264
 265         strncpy (canonical, path, PATH_MAX);
 266         canonical[PATH_MAX] = '\0';
 267         return canonical;
 268 }
 269
 270 int main(int argc, char ** argv)
 271 {
 272         int c;
 273         int rc;
 274         int flags = 0;
 275         int nomtab = 0;
 276         int retry_remount = 0;
 277         struct statfs statbuf;
 278         char * mountpoint;
 279
 280         if(argc && argv) {
 281                 thisprogram = argv[0];
 282         } else {
 283                 umount_cifs_usage();
 284                 return -EINVAL;
 285         }
 286
 287         if(argc < 2) {
 288                 umount_cifs_usage();
 289                 return -EINVAL;
 290         }
 291
 292         if(thisprogram == NULL)
 293                 thisprogram = "umount.cifs";
 294
 295         /* add sharename in opts string as unc= parm */
 296
 297         while ((c = getopt_long (argc, argv, "afhilnrvV",
 298                          longopts, NULL)) != -1) {
 299                 switch (c) {
 300 /* No code to do the following  option yet */
 301 /*              case 'a':
 302                         ++umount_all;
 303                         break; */
 304                 case '?':
 305                 case 'h':   /* help */
 306                         umount_cifs_usage();
 307                         exit(1);
 308                 case 'n':
 309                         ++nomtab;
 310                         break;
 311                 case 'f':
 312                         flags |= MNT_FORCE;
 313                         break;
 314                 case 'l':
 315                         flags |= MNT_DETACH; /* lazy unmount */
 316                         break;
 317                 case 'e':
 318                         flags |= MNT_EXPIRE; /* gradually timeout */
 319                         break;
 320                 case 'r':
 321                         ++retry_remount;
 322                         break;
 323                 case 'v':
 324                         ++verboseflg;
 325                         break;
 326                 case 'V':
 327                         printf ("umount.cifs version: %s.%s%s\n",
 328                                 UNMOUNT_CIFS_VERSION_MAJOR,
 329                                 UNMOUNT_CIFS_VERSION_MINOR,
 330                                 UNMOUNT_CIFS_VENDOR_SUFFIX);
 331                         exit (0);
 332                 default:
 333                         printf("unknown unmount option %c\n",c);
 334                         umount_cifs_usage();
 335                         exit(1);
 336                 }
 337         }
 338
 339         /* move past the umount options */
 340         argv += optind;
 341         argc -= optind;
 342
 343         mountpoint = canonicalize(argv[0]);
 344
 345         if((argc < 1) || (argv[0] == NULL)) {
 346                 printf("\nMissing name of unmount directory\n");
 347                 umount_cifs_usage();
 348                 return -EINVAL;
 349         }
 350
 351         if(verboseflg)
 352                 printf("optind %d unmount dir %s\n",optind, mountpoint);
 353
 354         /* check if running effectively root */
 355         if(geteuid() != 0) {
 356                 printf("Trying to unmount when %s not installed suid\n",thisprogram);
 357                 if(verboseflg)
 358                         printf("euid = %d\n",geteuid());
 359                 return -EACCES;
 360         }
 361
 362         /* fixup path if needed */
 363
 364         /* Trim any trailing slashes */
 365         while ((strlen(mountpoint) > 1) &&
 366                 (mountpoint[strlen(mountpoint)-1] == '/'))
 367         {
 368                 mountpoint[strlen(mountpoint)-1] = '\0';
 369         }
 370
 371         /* make sure that this is a cifs filesystem */
 372         rc = statfs(mountpoint, &statbuf);
 373
 374         if(rc || (statbuf.f_type != CIFS_MAGIC_NUMBER)) {
 375                 printf("This utility only unmounts cifs filesystems.\n");
 376                 return -EINVAL;
 377         }
 378
 379         /* check if our uid was the one who mounted */
 380         rc = umount_check_perm(mountpoint);
 381         if (rc) {
 382                 printf("Not permitted to unmount\n");
 383                 return rc;
 384         }
 385
 386         if(umount2(mountpoint, flags)) {
 387         /* remember to kill daemon on error */
 388                 switch (errno) {
 389                 case 0:
 390                         printf("unmount failed but no error number set\n");
 391                         break;
 392                 default:
 393                         printf("unmount error %d = %s\n",errno,strerror(errno));
 394                 }
 395                 printf("Refer to the umount.cifs(8) manual page (man 8 umount.cifs)\n");
 396                 return -1;
 397         } else {
 398                 if(verboseflg)
 399                         printf("umount2 succeeded\n");
 400                 if(nomtab == 0)
 401                         remove_from_mtab(mountpoint);
 402         }
 403
 404         return 0;
 405 }
 406