source/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 2 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, write to the Free Software
  17    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  18
  19 #ifndef _GNU_SOURCE
  20 #define _GNU_SOURCE
  21 #endif
  22
  23 #include <stdlib.h>
  24 #include <stdio.h>
  25 #include <unistd.h>
  26 #include <ctype.h>
  27 #include <sys/types.h>
  28 #include <sys/mount.h>
  29 #include <sys/ioctl.h>
  30 #include <sys/stat.h>
  31 #include <sys/vfs.h>
  32 #include <fcntl.h>
  33 #include <getopt.h>
  34 #include <errno.h>
  35 #include <string.h>
  36 #include <mntent.h>
  37
  38 #define UNMOUNT_CIFS_VERSION_MAJOR "0"
  39 #define UNMOUNT_CIFS_VERSION_MINOR "5"
  40
  41 #ifndef UNMOUNT_CIFS_VENDOR_SUFFIX
  42 #define UNMOUNT_CIFS_VENDOR_SUFFIX ""
  43 #endif
  44
  45 #ifndef MNT_DETACH
  46 #define MNT_DETACH 0x02
  47 #endif
  48
  49 #ifndef MNT_EXPIRE
  50 #define MNT_EXPIRE 0x04
  51 #endif
  52
  53 #ifndef MOUNTED_LOCK
  54 #define MOUNTED_LOCK    "/etc/mtab~"
  55 #endif
  56 #ifndef MOUNTED_TEMP
  57 #define MOUNTED_TEMP    "/etc/mtab.tmp"
  58 #endif
  59
  60 #define CIFS_IOC_CHECKUMOUNT _IO(0xCF, 2)
  61 #define CIFS_MAGIC_NUMBER 0xFF534D42   /* the first four bytes of SMB PDU */
  62
  63 static struct option longopts[] = {
  64         { "all", 0, NULL, 'a' },
  65         { "help",0, NULL, 'h' },
  66         { "read-only", 0, NULL, 'r' },
  67         { "ro", 0, NULL, 'r' },
  68         { "verbose", 0, NULL, 'v' },
  69         { "version", 0, NULL, 'V' },
  70         { "expire", 0, NULL, 'e' },
  71         { "force", 0, 0, 'f' },
  72         { "lazy", 0, 0, 'l' },
  73         { "no-mtab", 0, 0, 'n' },
  74         { NULL, 0, NULL, 0 }
  75 };
  76
  77 char * thisprogram;
  78 int verboseflg = 0;
  79
  80 static void umount_cifs_usage(void)
  81 {
  82         printf("\nUsage:  %s <remotetarget> <dir>\n", thisprogram);
  83         printf("\nUnmount the specified directory\n");
  84         printf("\nLess commonly used options:");
  85         printf("\n\t-r\tIf mount fails, retry with readonly remount.");
  86         printf("\n\t-n\tDo not write to mtab.");
  87         printf("\n\t-f\tAttempt a forced unmount, even if the fs is busy.");
  88         printf("\n\t-l\tAttempt lazy unmount, Unmount now, cleanup later.");
  89         printf("\n\t-v\tEnable verbose mode (may be useful for debugging).");
  90         printf("\n\t-h\tDisplay this help.");
  91         printf("\n\nOptions are described in more detail in the manual page");
  92         printf("\n\tman 8 umount.cifs\n");
  93         printf("\nTo display the version number of the cifs umount utility:");
  94         printf("\n\t%s -V\n",thisprogram);
  95         printf("\nInvoking the umount utility on cifs mounts, can execute");
  96         printf(" /sbin/umount.cifs (if present and umount -i is not specified.\n");
  97 }
  98
  99 static int umount_check_perm(char * dir)
 100 {
 101         int fileid;
 102         int rc;
 103
 104         /* allow root to unmount, no matter what */
 105         if(getuid() == 0)
 106                 return 0;
 107
 108         /* presumably can not chdir into the target as we do on mount */
 109         fileid = open(dir, O_RDONLY | O_DIRECTORY | O_NOFOLLOW, 0);
 110         if(fileid == -1) {
 111                 if(verboseflg)
 112                         printf("error opening mountpoint %d %s",errno,strerror(errno));
 113                 return errno;
 114         }
 115
 116         rc = ioctl(fileid, CIFS_IOC_CHECKUMOUNT, NULL);
 117
 118         if(verboseflg)
 119                 printf("ioctl returned %d with errno %d %s\n",rc,errno,strerror(errno));
 120
 121         if(rc == ENOTTY) {
 122                 printf("user unmounting via %s is an optional feature of",thisprogram);
 123                 printf(" the cifs filesystem driver (cifs.ko)");
 124                 printf("\n\tand requires cifs.ko version 1.32 or later\n");
 125         } else if (rc > 0)
 126                 printf("user unmount of %s failed with %d %s\n",dir,errno,strerror(errno));
 127         close(fileid);
 128
 129         return rc;
 130 }
 131
 132 int lock_mtab(void)
 133 {
 134         int rc;
 135
 136         rc = mknod(MOUNTED_LOCK , 0600, 0);
 137         if(rc == -1)
 138                 printf("\ngetting lock file %s failed with %s\n",MOUNTED_LOCK,
 139                                 strerror(errno));
 140
 141         return rc;
 142
 143 }
 144
 145 void unlock_mtab(void)
 146 {
 147         unlink(MOUNTED_LOCK);
 148 }
 149
 150 int remove_from_mtab(char * mountpoint)
 151 {
 152         int rc;
 153         int num_matches;
 154         FILE * org_fd;
 155         FILE * new_fd;
 156         struct mntent * mount_entry;
 157
 158         /* Do we need to check if it is a symlink to e.g. /proc/mounts
 159         in which case we probably do not want to update it? */
 160
 161         /* Do we first need to check if it is writable? */
 162
 163         if (lock_mtab()) {
 164                 printf("Mount table locked\n");
 165                 return -EACCES;
 166         }
 167
 168         if(verboseflg)
 169                 printf("attempting to remove from mtab\n");
 170
 171         org_fd = setmntent(MOUNTED, "r");
 172
 173         if(org_fd == NULL) {
 174                 printf("Can not open %s\n",MOUNTED);
 175                 unlock_mtab();
 176                 return -EIO;
 177         }
 178
 179         new_fd = setmntent(MOUNTED_TEMP,"w");
 180         if(new_fd == NULL) {
 181                 printf("Can not open temp file %s", MOUNTED_TEMP);
 182                 endmntent(org_fd);
 183                 unlock_mtab();
 184                 return -EIO;
 185         }
 186
 187         /* BB fix so we only remove the last entry that matches BB */
 188         num_matches = 0;
 189         while((mount_entry = getmntent(org_fd)) != NULL) {
 190                 if(strcmp(mount_entry->mnt_dir, mountpoint) == 0) {
 191                         num_matches++;
 192                 }
 193         }
 194         if(verboseflg)
 195                 printf("%d matching entries in mount table\n", num_matches);
 196
 197         /* Is there a better way to seek back to the first entry in mtab? */
 198         endmntent(org_fd);
 199         org_fd = setmntent(MOUNTED, "r");
 200
 201         if(org_fd == NULL) {
 202                 printf("Can not open %s\n",MOUNTED);
 203                 unlock_mtab();
 204                 return -EIO;
 205         }
 206
 207         while((mount_entry = getmntent(org_fd)) != NULL) {
 208                 if(strcmp(mount_entry->mnt_dir, mountpoint) != 0) {
 209                         addmntent(new_fd, mount_entry);
 210                 } else {
 211                         if(num_matches != 1) {
 212                                 addmntent(new_fd, mount_entry);
 213                                 num_matches--;
 214                         } else if(verboseflg)
 215                                 printf("entry not copied (ie entry is removed)\n");
 216                 }
 217         }
 218
 219         if(verboseflg)
 220                 printf("done updating tmp file\n");
 221         rc = fchmod (fileno (new_fd), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
 222         if(rc < 0) {
 223                 printf("error %s changing mode of %s\n", strerror(errno),
 224                         MOUNTED_TEMP);
 225         }
 226         endmntent(new_fd);
 227
 228         rc = rename(MOUNTED_TEMP, MOUNTED);
 229
 230         if(rc < 0) {
 231                 printf("failure %s renaming %s to %s\n",strerror(errno),
 232                         MOUNTED_TEMP, MOUNTED);
 233                 unlock_mtab();
 234                 return -EIO;
 235         }
 236
 237         unlock_mtab();
 238
 239         return rc;
 240 }
 241
 242 int main(int argc, char ** argv)
 243 {
 244         int c;
 245         int rc;
 246         int flags = 0;
 247         int nomtab = 0;
 248         int retry_remount = 0;
 249         struct statfs statbuf;
 250         char * mountpoint;
 251
 252         if(argc && argv) {
 253                 thisprogram = argv[0];
 254         } else {
 255                 umount_cifs_usage();
 256                 return -EINVAL;
 257         }
 258
 259         if(argc < 2) {
 260                 umount_cifs_usage();
 261                 return -EINVAL;
 262         }
 263
 264         if(thisprogram == NULL)
 265                 thisprogram = "umount.cifs";
 266
 267         /* add sharename in opts string as unc= parm */
 268
 269         while ((c = getopt_long (argc, argv, "afhilnrvV",
 270                          longopts, NULL)) != -1) {
 271                 switch (c) {
 272 /* No code to do the following  option yet */
 273 /*              case 'a':
 274                         ++umount_all;
 275                         break; */
 276                 case '?':
 277                 case 'h':   /* help */
 278                         umount_cifs_usage();
 279                         exit(1);
 280                 case 'n':
 281                         ++nomtab;
 282                         break;
 283                 case 'f':
 284                         flags |= MNT_FORCE;
 285                         break;
 286                 case 'l':
 287                         flags |= MNT_DETACH; /* lazy unmount */
 288                         break;
 289                 case 'e':
 290                         flags |= MNT_EXPIRE; /* gradually timeout */
 291                         break;
 292                 case 'r':
 293                         ++retry_remount;
 294                         break;
 295                 case 'v':
 296                         ++verboseflg;
 297                         break;
 298                 case 'V':
 299                         printf ("umount.cifs version: %s.%s%s\n",
 300                                 UNMOUNT_CIFS_VERSION_MAJOR,
 301                                 UNMOUNT_CIFS_VERSION_MINOR,
 302                                 UNMOUNT_CIFS_VENDOR_SUFFIX);
 303                         exit (0);
 304                 default:
 305                         printf("unknown unmount option %c\n",c);
 306                         umount_cifs_usage();
 307                         exit(1);
 308                 }
 309         }
 310
 311         /* move past the umount options */
 312         argv += optind;
 313         argc -= optind;
 314
 315         mountpoint = argv[0];
 316
 317         if((argc < 1) || (argv[0] == NULL)) {
 318                 printf("\nMissing name of unmount directory\n");
 319                 umount_cifs_usage();
 320                 return -EINVAL;
 321         }
 322
 323         if(verboseflg)
 324                 printf("optind %d unmount dir %s\n",optind, mountpoint);
 325
 326         /* check if running effectively root */
 327         if(geteuid() != 0) {
 328                 printf("Trying to unmount when %s not installed suid\n",thisprogram);
 329                 if(verboseflg)
 330                         printf("euid = %d\n",geteuid());
 331                 return -EACCES;
 332         }
 333
 334         /* fixup path if needed */
 335
 336         /* make sure that this is a cifs filesystem */
 337         rc = statfs(mountpoint, &statbuf);
 338
 339         if(rc || (statbuf.f_type != CIFS_MAGIC_NUMBER)) {
 340                 printf("This utility only unmounts cifs filesystems.\n");
 341                 return -EINVAL;
 342         }
 343
 344         /* check if our uid was the one who mounted */
 345         rc = umount_check_perm(mountpoint);
 346         if (rc) {
 347                 printf("Not permitted to unmount\n");
 348                 return rc;
 349         }
 350
 351         if(umount2(mountpoint, flags)) {
 352         /* remember to kill daemon on error */
 353                 switch (errno) {
 354                 case 0:
 355                         printf("unmount failed but no error number set\n");
 356                         break;
 357                 default:
 358                         printf("unmount error %d = %s\n",errno,strerror(errno));
 359                 }
 360                 printf("Refer to the umount.cifs(8) manual page (man 8 umount.cifs)\n");
 361                 return -1;
 362         } else {
 363                 if(verboseflg)
 364                         printf("umount2 succeeded\n");
 365                 if(nomtab == 0)
 366                         remove_from_mtab(mountpoint);
 367         }
 368
 369         return 0;
 370 }
 371