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 #include <fstab.h>
  38
  39 #define UNMOUNT_CIFS_VERSION_MAJOR "0"
  40 #define UNMOUNT_CIFS_VERSION_MINOR "5"
  41
  42 #ifndef UNMOUNT_CIFS_VENDOR_SUFFIX
  43 #define UNMOUNT_CIFS_VENDOR_SUFFIX ""
  44 #endif
  45
  46 #ifndef MNT_DETACH
  47 #define MNT_DETACH 0x02
  48 #endif
  49
  50 #ifndef MNT_EXPIRE
  51 #define MNT_EXPIRE 0x04
  52 #endif
  53
  54 #ifndef MOUNTED_LOCK
  55 #define MOUNTED_LOCK    "/etc/mtab~"
  56 #endif
  57 #ifndef MOUNTED_TEMP
  58 #define MOUNTED_TEMP    "/etc/mtab.tmp"
  59 #endif
  60
  61 #define CIFS_IOC_CHECKUMOUNT _IO(0xCF, 2)
  62 #define CIFS_MAGIC_NUMBER 0xFF534D42   /* the first four bytes of SMB PDU */
  63
  64 static struct option longopts[] = {
  65         { "all", 0, NULL, 'a' },
  66         { "help",0, NULL, 'h' },
  67         { "read-only", 0, NULL, 'r' },
  68         { "ro", 0, NULL, 'r' },
  69         { "verbose", 0, NULL, 'v' },
  70         { "version", 0, NULL, 'V' },
  71         { "expire", 0, NULL, 'e' },
  72         { "force", 0, 0, 'f' },
  73         { "lazy", 0, 0, 'l' },
  74         { "no-mtab", 0, 0, 'n' },
  75         { NULL, 0, NULL, 0 }
  76 };
  77
  78 char * thisprogram;
  79 int verboseflg = 0;
  80
  81 static void umount_cifs_usage(void)
  82 {
  83         printf("\nUsage:  %s <remotetarget> <dir>\n", thisprogram);
  84         printf("\nUnmount the specified directory\n");
  85         printf("\nLess commonly used options:");
  86         printf("\n\t-r\tIf mount fails, retry with readonly remount.");
  87         printf("\n\t-n\tDo not write to mtab.");
  88         printf("\n\t-f\tAttempt a forced unmount, even if the fs is busy.");
  89         printf("\n\t-l\tAttempt lazy unmount, Unmount now, cleanup later.");
  90         printf("\n\t-v\tEnable verbose mode (may be useful for debugging).");
  91         printf("\n\t-h\tDisplay this help.");
  92         printf("\n\nOptions are described in more detail in the manual page");
  93         printf("\n\tman 8 umount.cifs\n");
  94         printf("\nTo display the version number of the cifs umount utility:");
  95         printf("\n\t%s -V\n",thisprogram);
  96         printf("\nInvoking the umount utility on cifs mounts, can execute");
  97         printf(" /sbin/umount.cifs (if present and umount -i is not specified.\n");
  98 }
  99
 100 static int umount_check_perm(char * dir)
 101 {
 102         int fileid;
 103         int rc;
 104
 105         /* allow root to unmount, no matter what */
 106         if(getuid() == 0)
 107                 return 0;
 108
 109         /* presumably can not chdir into the target as we do on mount */
 110         fileid = open(dir, O_RDONLY | O_DIRECTORY | O_NOFOLLOW, 0);
 111         if(fileid == -1) {
 112                 if(verboseflg)
 113                         printf("error opening mountpoint %d %s",errno,strerror(errno));
 114                 return errno;
 115         }
 116
 117         rc = ioctl(fileid, CIFS_IOC_CHECKUMOUNT, NULL);
 118
 119         if(verboseflg)
 120                 printf("ioctl returned %d with errno %d %s\n",rc,errno,strerror(errno));
 121
 122         if(rc == ENOTTY) {
 123                 printf("user unmounting via %s is an optional feature of",thisprogram);
 124                 printf(" the cifs filesystem driver (cifs.ko)");
 125                 printf("\n\tand requires cifs.ko version 1.32 or later\n");
 126         } else if (rc > 0)
 127                 printf("user unmount of %s failed with %d %s\n",dir,errno,strerror(errno));
 128         close(fileid);
 129
 130         return rc;
 131 }
 132
 133 int lock_mtab(void)
 134 {
 135         int rc;
 136
 137         rc = mknod(MOUNTED_LOCK , 0600, 0);
 138         if(rc == -1)
 139                 printf("\ngetting lock file %s failed with %s\n",MOUNTED_LOCK,
 140                                 strerror(errno));
 141
 142         return rc;
 143
 144 }
 145
 146 void unlock_mtab(void)
 147 {
 148         unlink(MOUNTED_LOCK);
 149 }
 150
 151 int remove_from_mtab(char * mountpoint)
 152 {
 153         int rc;
 154         int num_matches;
 155         FILE * org_fd;
 156         FILE * new_fd;
 157         struct mntent * mount_entry;
 158
 159         /* Do we need to check if it is a symlink to e.g. /proc/mounts
 160         in which case we probably do not want to update it? */
 161
 162         /* Do we first need to check if it is writable? */
 163
 164         if (lock_mtab()) {
 165                 printf("Mount table locked\n");
 166                 return -EACCES;
 167         }
 168
 169         if(verboseflg)
 170                 printf("attempting to remove from mtab\n");
 171
 172         org_fd = setmntent(MOUNTED, "r");
 173
 174         if(org_fd == NULL) {
 175                 printf("Can not open %s\n",MOUNTED);
 176                 unlock_mtab();
 177                 return -EIO;
 178         }
 179
 180         new_fd = setmntent(MOUNTED_TEMP,"w");
 181         if(new_fd == NULL) {
 182                 printf("Can not open temp file %s", MOUNTED_TEMP);
 183                 endmntent(org_fd);
 184                 unlock_mtab();
 185                 return -EIO;
 186         }
 187
 188         /* BB fix so we only remove the last entry that matches BB */
 189         num_matches = 0;
 190         while((mount_entry = getmntent(org_fd)) != NULL) {
 191                 if(strcmp(mount_entry->mnt_dir, mountpoint) == 0) {
 192                         num_matches++;
 193                 }
 194         }
 195         if(verboseflg)
 196                 printf("%d matching entries in mount table\n", num_matches);
 197
 198         /* Is there a better way to seek back to the first entry in mtab? */
 199         endmntent(org_fd);
 200         org_fd = setmntent(MOUNTED, "r");
 201
 202         if(org_fd == NULL) {
 203                 printf("Can not open %s\n",MOUNTED);
 204                 unlock_mtab();
 205                 return -EIO;
 206         }
 207
 208         while((mount_entry = getmntent(org_fd)) != NULL) {
 209                 if(strcmp(mount_entry->mnt_dir, mountpoint) != 0) {
 210                         addmntent(new_fd, mount_entry);
 211                 } else {
 212                         if(num_matches != 1) {
 213                                 addmntent(new_fd, mount_entry);
 214                                 num_matches--;
 215                         } else if(verboseflg)
 216                                 printf("entry not copied (ie entry is removed)\n");
 217                 }
 218         }
 219
 220         if(verboseflg)
 221                 printf("done updating tmp file\n");
 222         rc = fchmod (fileno (new_fd), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
 223         if(rc < 0) {
 224                 printf("error %s changing mode of %s\n", strerror(errno),
 225                         MOUNTED_TEMP);
 226         }
 227         endmntent(new_fd);
 228
 229         rc = rename(MOUNTED_TEMP, MOUNTED);
 230
 231         if(rc < 0) {
 232                 printf("failure %s renaming %s to %s\n",strerror(errno),
 233                         MOUNTED_TEMP, MOUNTED);
 234                 unlock_mtab();
 235                 return -EIO;
 236         }
 237
 238         unlock_mtab();
 239
 240         return rc;
 241 }
 242
 243 int main(int argc, char ** argv)
 244 {
 245         int c;
 246         int rc;
 247         int flags = 0;
 248         int nomtab = 0;
 249         int retry_remount = 0;
 250         struct statfs statbuf;
 251         char * mountpoint;
 252
 253         if(argc && argv) {
 254                 thisprogram = argv[0];
 255         } else {
 256                 umount_cifs_usage();
 257                 return -EINVAL;
 258         }
 259
 260         if(argc < 2) {
 261                 umount_cifs_usage();
 262                 return -EINVAL;
 263         }
 264
 265         if(thisprogram == NULL)
 266                 thisprogram = "umount.cifs";
 267
 268         /* add sharename in opts string as unc= parm */
 269
 270         while ((c = getopt_long (argc, argv, "afhilnrvV",
 271                          longopts, NULL)) != -1) {
 272                 switch (c) {
 273 /* No code to do the following  option yet */
 274 /*              case 'a':
 275                         ++umount_all;
 276                         break; */
 277                 case '?':
 278                 case 'h':   /* help */
 279                         umount_cifs_usage();
 280                         exit(1);
 281                 case 'n':
 282                         ++nomtab;
 283                         break;
 284                 case 'f':
 285                         flags |= MNT_FORCE;
 286                         break;
 287                 case 'l':
 288                         flags |= MNT_DETACH; /* lazy unmount */
 289                         break;
 290                 case 'e':
 291                         flags |= MNT_EXPIRE; /* gradually timeout */
 292                         break;
 293                 case 'r':
 294                         ++retry_remount;
 295                         break;
 296                 case 'v':
 297                         ++verboseflg;
 298                         break;
 299                 case 'V':
 300                         printf ("umount.cifs version: %s.%s%s\n",
 301                                 UNMOUNT_CIFS_VERSION_MAJOR,
 302                                 UNMOUNT_CIFS_VERSION_MINOR,
 303                                 UNMOUNT_CIFS_VENDOR_SUFFIX);
 304                         exit (0);
 305                 default:
 306                         printf("unknown unmount option %c\n",c);
 307                         umount_cifs_usage();
 308                         exit(1);
 309                 }
 310         }
 311
 312         /* move past the umount options */
 313         argv += optind;
 314         argc -= optind;
 315
 316         mountpoint = argv[0];
 317
 318         if((argc < 1) || (argv[0] == NULL)) {
 319                 printf("\nMissing name of unmount directory\n");
 320                 umount_cifs_usage();
 321                 return -EINVAL;
 322         }
 323
 324         if(verboseflg)
 325                 printf("optind %d unmount dir %s\n",optind, mountpoint);
 326
 327         /* check if running effectively root */
 328         if(geteuid() != 0) {
 329                 printf("Trying to unmount when %s not installed suid\n",thisprogram);
 330                 if(verboseflg)
 331                         printf("euid = %d\n",geteuid());
 332                 return -EACCES;
 333         }
 334
 335         /* fixup path if needed */
 336
 337         /* make sure that this is a cifs filesystem */
 338         rc = statfs(mountpoint, &statbuf);
 339
 340         if(rc || (statbuf.f_type != CIFS_MAGIC_NUMBER)) {
 341                 printf("This utility only unmounts cifs filesystems.\n");
 342                 return -EINVAL;
 343         }
 344
 345         /* check if our uid was the one who mounted */
 346         rc = umount_check_perm(mountpoint);
 347         if (rc) {
 348                 printf("Not permitted to unmount\n");
 349                 return rc;
 350         }
 351
 352         if(umount2(mountpoint, flags)) {
 353         /* remember to kill daemon on error */
 354                 switch (errno) {
 355                 case 0:
 356                         printf("unmount failed but no error number set\n");
 357                         break;
 358                 default:
 359                         printf("unmount error %d = %s\n",errno,strerror(errno));
 360                 }
 361                 printf("Refer to the umount.cifs(8) manual page (man 8 umount.cifs)\n");
 362                 return -1;
 363         } else {
 364                 if(verboseflg)
 365                         printf("umount2 succeeded\n");
 366                 if(nomtab == 0)
 367                         remove_from_mtab(mountpoint);
 368         }
 369
 370         return 0;
 371 }
 372