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 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
  37 #define UNMOUNT_CIFS_VERSION_MAJOR "0"
  38 #define UNMOUNT_CIFS_VERSION_MINOR "5"
  39
  40 #ifndef UNMOUNT_CIFS_VENDOR_SUFFIX
  41  #ifdef _SAMBA_BUILD_
  42   #include "include/version.h"
  43   #ifdef SAMBA_VERSION_VENDOR_SUFFIX
  44    #define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING"-"SAMBA_VERSION_VENDOR_SUFFIX
  45   #else
  46    #define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING
  47   #endif /* SAMBA_VERSION_OFFICIAL_STRING and SAMBA_VERSION_VENDOR_SUFFIX */
  48  #else
  49   #define UNMOUNT_CIFS_VENDOR_SUFFIX ""
  50  #endif /* _SAMBA_BUILD_ */
  51 #endif /* UNMOUNT_CIFS_VENDOR_SUFFIX */
  52
  53 #ifndef MNT_DETACH
  54 #define MNT_DETACH 0x02
  55 #endif
  56
  57 #ifndef MNT_EXPIRE
  58 #define MNT_EXPIRE 0x04
  59 #endif
  60
  61 #ifndef MOUNTED_LOCK
  62 #define MOUNTED_LOCK    "/etc/mtab~"
  63 #endif
  64 #ifndef MOUNTED_TEMP
  65 #define MOUNTED_TEMP    "/etc/mtab.tmp"
  66 #endif
  67
  68 #define CIFS_IOC_CHECKUMOUNT _IO(0xCF, 2)
  69 #define CIFS_MAGIC_NUMBER 0xFF534D42   /* the first four bytes of SMB PDU */
  70
  71 static struct option longopts[] = {
  72         { "all", 0, NULL, 'a' },
  73         { "help",0, NULL, 'h' },
  74         { "read-only", 0, NULL, 'r' },
  75         { "ro", 0, NULL, 'r' },
  76         { "verbose", 0, NULL, 'v' },
  77         { "version", 0, NULL, 'V' },
  78         { "expire", 0, NULL, 'e' },
  79         { "force", 0, 0, 'f' },
  80         { "lazy", 0, 0, 'l' },
  81         { "no-mtab", 0, 0, 'n' },
  82         { NULL, 0, NULL, 0 }
  83 };
  84
  85 const char * thisprogram;
  86 int verboseflg = 0;
  87
  88 static void umount_cifs_usage(void)
  89 {
  90         printf("\nUsage:  %s <remotetarget> <dir>\n", thisprogram);
  91         printf("\nUnmount the specified directory\n");
  92         printf("\nLess commonly used options:");
  93         printf("\n\t-r\tIf mount fails, retry with readonly remount.");
  94         printf("\n\t-n\tDo not write to mtab.");
  95         printf("\n\t-f\tAttempt a forced unmount, even if the fs is busy.");
  96         printf("\n\t-l\tAttempt lazy unmount, Unmount now, cleanup later.");
  97         printf("\n\t-v\tEnable verbose mode (may be useful for debugging).");
  98         printf("\n\t-h\tDisplay this help.");
  99         printf("\n\nOptions are described in more detail in the manual page");
 100         printf("\n\tman 8 umount.cifs\n");
 101         printf("\nTo display the version number of the cifs umount utility:");
 102         printf("\n\t%s -V\n",thisprogram);
 103         printf("\nInvoking the umount utility on cifs mounts, can execute");
 104         printf(" /sbin/umount.cifs (if present and umount -i is not specified.\n");
 105 }
 106
 107 static int umount_check_perm(char * dir)
 108 {
 109         int fileid;
 110         int rc;
 111
 112         /* allow root to unmount, no matter what */
 113         if(getuid() == 0)
 114                 return 0;
 115
 116         /* presumably can not chdir into the target as we do on mount */
 117         fileid = open(dir, O_RDONLY | O_DIRECTORY | O_NOFOLLOW, 0);
 118         if(fileid == -1) {
 119                 if(verboseflg)
 120                         printf("error opening mountpoint %d %s",errno,strerror(errno));
 121                 return errno;
 122         }
 123
 124         rc = ioctl(fileid, CIFS_IOC_CHECKUMOUNT, NULL);
 125
 126         if(verboseflg)
 127                 printf("ioctl returned %d with errno %d %s\n",rc,errno,strerror(errno));
 128
 129         if(rc == ENOTTY) {
 130                 printf("user unmounting via %s is an optional feature of",thisprogram);
 131                 printf(" the cifs filesystem driver (cifs.ko)");
 132                 printf("\n\tand requires cifs.ko version 1.32 or later\n");
 133         } else if (rc != 0)
 134                 printf("user unmount of %s failed with %d %s\n",dir,errno,strerror(errno));
 135         close(fileid);
 136
 137         return rc;
 138 }
 139
 140 static int lock_mtab(void)
 141 {
 142         int rc;
 143
 144         rc = mknod(MOUNTED_LOCK , 0600, 0);
 145         if(rc == -1)
 146                 printf("\ngetting lock file %s failed with %s\n",MOUNTED_LOCK,
 147                                 strerror(errno));
 148
 149         return rc;
 150
 151 }
 152
 153 static void unlock_mtab(void)
 154 {
 155         unlink(MOUNTED_LOCK);
 156 }
 157
 158 static int remove_from_mtab(char * mountpoint)
 159 {
 160         int rc;
 161         int num_matches;
 162         FILE * org_fd;
 163         FILE * new_fd;
 164         struct mntent * mount_entry;
 165
 166         /* Do we need to check if it is a symlink to e.g. /proc/mounts
 167         in which case we probably do not want to update it? */
 168
 169         /* Do we first need to check if it is writable? */
 170
 171         if (lock_mtab()) {
 172                 printf("Mount table locked\n");
 173                 return -EACCES;
 174         }
 175
 176         if(verboseflg)
 177                 printf("attempting to remove from mtab\n");
 178
 179         org_fd = setmntent(MOUNTED, "r");
 180
 181         if(org_fd == NULL) {
 182                 printf("Can not open %s\n",MOUNTED);
 183                 unlock_mtab();
 184                 return -EIO;
 185         }
 186
 187         new_fd = setmntent(MOUNTED_TEMP,"w");
 188         if(new_fd == NULL) {
 189                 printf("Can not open temp file %s", MOUNTED_TEMP);
 190                 endmntent(org_fd);
 191                 unlock_mtab();
 192                 return -EIO;
 193         }
 194
 195         /* BB fix so we only remove the last entry that matches BB */
 196         num_matches = 0;
 197         while((mount_entry = getmntent(org_fd)) != NULL) {
 198                 if(strcmp(mount_entry->mnt_dir, mountpoint) == 0) {
 199                         num_matches++;
 200                 }
 201         }
 202         if(verboseflg)
 203                 printf("%d matching entries in mount table\n", num_matches);
 204
 205         /* Is there a better way to seek back to the first entry in mtab? */
 206         endmntent(org_fd);
 207         org_fd = setmntent(MOUNTED, "r");
 208
 209         if(org_fd == NULL) {
 210                 printf("Can not open %s\n",MOUNTED);
 211                 unlock_mtab();
 212                 return -EIO;
 213         }
 214
 215         while((mount_entry = getmntent(org_fd)) != NULL) {
 216                 if(strcmp(mount_entry->mnt_dir, mountpoint) != 0) {
 217                         addmntent(new_fd, mount_entry);
 218                 } else {
 219                         if(num_matches != 1) {
 220                                 addmntent(new_fd, mount_entry);
 221                                 num_matches--;
 222                         } else if(verboseflg)
 223                                 printf("entry not copied (ie entry is removed)\n");
 224                 }
 225         }
 226
 227         if(verboseflg)
 228                 printf("done updating tmp file\n");
 229         rc = fchmod (fileno (new_fd), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
 230         if(rc < 0) {
 231                 printf("error %s changing mode of %s\n", strerror(errno),
 232                         MOUNTED_TEMP);
 233         }
 234         endmntent(new_fd);
 235
 236         rc = rename(MOUNTED_TEMP, MOUNTED);
 237
 238         if(rc < 0) {
 239                 printf("failure %s renaming %s to %s\n",strerror(errno),
 240                         MOUNTED_TEMP, MOUNTED);
 241                 unlock_mtab();
 242                 return -EIO;
 243         }
 244
 245         unlock_mtab();
 246
 247         return rc;
 248 }
 249
 250 int main(int argc, char ** argv)
 251 {
 252         int c;
 253         int rc;
 254         int flags = 0;
 255         int nomtab = 0;
 256         int retry_remount = 0;
 257         struct statfs statbuf;
 258         char * mountpoint;
 259
 260         if(argc && argv) {
 261                 thisprogram = argv[0];
 262         } else {
 263                 umount_cifs_usage();
 264                 return -EINVAL;
 265         }
 266
 267         if(argc < 2) {
 268                 umount_cifs_usage();
 269                 return -EINVAL;
 270         }
 271
 272         if(thisprogram == NULL)
 273                 thisprogram = "umount.cifs";
 274
 275         /* add sharename in opts string as unc= parm */
 276
 277         while ((c = getopt_long (argc, argv, "afhilnrvV",
 278                          longopts, NULL)) != -1) {
 279                 switch (c) {
 280 /* No code to do the following  option yet */
 281 /*              case 'a':
 282                         ++umount_all;
 283                         break; */
 284                 case '?':
 285                 case 'h':   /* help */
 286                         umount_cifs_usage();
 287                         exit(1);
 288                 case 'n':
 289                         ++nomtab;
 290                         break;
 291                 case 'f':
 292                         flags |= MNT_FORCE;
 293                         break;
 294                 case 'l':
 295                         flags |= MNT_DETACH; /* lazy unmount */
 296                         break;
 297                 case 'e':
 298                         flags |= MNT_EXPIRE; /* gradually timeout */
 299                         break;
 300                 case 'r':
 301                         ++retry_remount;
 302                         break;
 303                 case 'v':
 304                         ++verboseflg;
 305                         break;
 306                 case 'V':
 307                         printf ("umount.cifs version: %s.%s%s\n",
 308                                 UNMOUNT_CIFS_VERSION_MAJOR,
 309                                 UNMOUNT_CIFS_VERSION_MINOR,
 310                                 UNMOUNT_CIFS_VENDOR_SUFFIX);
 311                         exit (0);
 312                 default:
 313                         printf("unknown unmount option %c\n",c);
 314                         umount_cifs_usage();
 315                         exit(1);
 316                 }
 317         }
 318
 319         /* move past the umount options */
 320         argv += optind;
 321         argc -= optind;
 322
 323         mountpoint = argv[0];
 324
 325         if((argc < 1) || (argv[0] == NULL)) {
 326                 printf("\nMissing name of unmount directory\n");
 327                 umount_cifs_usage();
 328                 return -EINVAL;
 329         }
 330
 331         if(verboseflg)
 332                 printf("optind %d unmount dir %s\n",optind, mountpoint);
 333
 334         /* check if running effectively root */
 335         if(geteuid() != 0) {
 336                 printf("Trying to unmount when %s not installed suid\n",thisprogram);
 337                 if(verboseflg)
 338                         printf("euid = %d\n",geteuid());
 339                 return -EACCES;
 340         }
 341
 342         /* fixup path if needed */
 343
 344         /* Trim any trailing slashes */
 345         while ((strlen(mountpoint) > 1) &&
 346                 (mountpoint[strlen(mountpoint)-1] == '/'))
 347         {
 348                 mountpoint[strlen(mountpoint)-1] = '\0';
 349         }
 350
 351         /* make sure that this is a cifs filesystem */
 352         rc = statfs(mountpoint, &statbuf);
 353
 354         if(rc || (statbuf.f_type != CIFS_MAGIC_NUMBER)) {
 355                 printf("This utility only unmounts cifs filesystems.\n");
 356                 return -EINVAL;
 357         }
 358
 359         /* check if our uid was the one who mounted */
 360         rc = umount_check_perm(mountpoint);
 361         if (rc) {
 362                 printf("Not permitted to unmount\n");
 363                 return rc;
 364         }
 365
 366         if(umount2(mountpoint, flags)) {
 367         /* remember to kill daemon on error */
 368                 switch (errno) {
 369                 case 0:
 370                         printf("unmount failed but no error number set\n");
 371                         break;
 372                 default:
 373                         printf("unmount error %d = %s\n",errno,strerror(errno));
 374                 }
 375                 printf("Refer to the umount.cifs(8) manual page (man 8 umount.cifs)\n");
 376                 return -1;
 377         } else {
 378                 if(verboseflg)
 379                         printf("umount2 succeeded\n");
 380                 if(nomtab == 0)
 381                         remove_from_mtab(mountpoint);
 382         }
 383
 384         return 0;
 385 }
 386