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
 150         /* Do we need to check if it is a symlink to e.g. /proc/mounts
 151         in which case we probably do not want to update it? */
 152
 153         /* Do we first need to check if it is writable? */
 154
 155         atexit(unlock_mtab);
 156         if (lock_mtab()) {
 157                 printf("Mount table locked\n");
 158                 return -EACCES;
 159         }
 160
 161         if(verboseflg)
 162                 printf("attempting to remove from mtab\n");
 163
 164         org_fd = setmntent(MOUNTED, "r");
 165
 166         if(org_fd == NULL) {
 167                 printf("Can not open %s\n",MOUNTED);
 168                 unlock_mtab();
 169                 return -EIO;
 170         }
 171
 172         new_fd = setmntent(MOUNTED_TEMP,"w");
 173         if(new_fd == NULL) {
 174                 printf("Can not open temp file %s", MOUNTED_TEMP);
 175                 endmntent(org_fd);
 176                 unlock_mtab();
 177                 return -EIO;
 178         }
 179
 180         /* BB fix so we only remove the last entry that matches BB */
 181         num_matches = 0;
 182         while((mount_entry = getmntent(org_fd)) != NULL) {
 183                 if(strcmp(mount_entry->mnt_dir, mountpoint) == 0) {
 184                         num_matches++;
 185                 }
 186         }
 187         if(verboseflg)
 188                 printf("%d matching entries in mount table\n", num_matches);
 189
 190         /* Is there a better way to seek back to the first entry in mtab? */
 191         endmntent(org_fd);
 192         org_fd = setmntent(MOUNTED, "r");
 193
 194         if(org_fd == NULL) {
 195                 printf("Can not open %s\n",MOUNTED);
 196                 unlock_mtab();
 197                 return -EIO;
 198         }
 199
 200         while((mount_entry = getmntent(org_fd)) != NULL) {
 201                 if(strcmp(mount_entry->mnt_dir, mountpoint) != 0) {
 202                         addmntent(new_fd, mount_entry);
 203                 } else {
 204                         if(num_matches != 1) {
 205                                 addmntent(new_fd, mount_entry);
 206                                 num_matches--;
 207                         } else if(verboseflg)
 208                                 printf("entry not copied (ie entry is removed)\n");
 209                 }
 210         }
 211
 212         if(verboseflg)
 213                 printf("done updating tmp file\n");
 214         rc = fchmod (fileno (new_fd), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
 215         if(rc < 0) {
 216                 printf("error %s changing mode of %s\n", strerror(errno),
 217                         MOUNTED_TEMP);
 218         }
 219         endmntent(new_fd);
 220
 221         rc = rename(MOUNTED_TEMP, MOUNTED);
 222
 223         if(rc < 0) {
 224                 printf("failure %s renaming %s to %s\n",strerror(errno),
 225                         MOUNTED_TEMP, MOUNTED);
 226                 unlock_mtab();
 227                 return -EIO;
 228         }
 229
 230         unlock_mtab();
 231
 232         return rc;
 233 }
 234
 235 /* Make a canonical pathname from PATH.  Returns a freshly malloced string.
 236    It is up the *caller* to ensure that the PATH is sensible.  i.e.
 237    canonicalize ("/dev/fd0/.") returns "/dev/fd0" even though ``/dev/fd0/.''
 238    is not a legal pathname for ``/dev/fd0''  Anything we cannot parse
 239    we return unmodified.   */
 240 static char *
 241 canonicalize(char *path)
 242 {
 243         char *canonical;
 244
 245         if (path == NULL) {
 246                 return NULL;
 247         }
 248
 249         if (strlen(path) > PATH_MAX) {
 250                 fprintf(stderr, "Mount point string too long\n");
 251                 return NULL;
 252         }
 253
 254         canonical = (char *)malloc (PATH_MAX + 1);
 255
 256         if (!canonical) {
 257                 fprintf(stderr, "Error! Not enough memory!\n");
 258                 return NULL;
 259         }
 260
 261         if (realpath (path, canonical))
 262                 return canonical;
 263
 264         strncpy (canonical, path, PATH_MAX);
 265         canonical[PATH_MAX] = '\0';
 266         return canonical;
 267 }
 268
 269 int main(int argc, char ** argv)
 270 {
 271         int c;
 272         int rc;
 273         int flags = 0;
 274         int nomtab = 0;
 275         int retry_remount = 0;
 276         struct statfs statbuf;
 277         char * mountpoint;
 278
 279         if(argc && argv) {
 280                 thisprogram = argv[0];
 281         } else {
 282                 umount_cifs_usage();
 283                 return -EINVAL;
 284         }
 285
 286         if(argc < 2) {
 287                 umount_cifs_usage();
 288                 return -EINVAL;
 289         }
 290
 291         if(thisprogram == NULL)
 292                 thisprogram = "umount.cifs";
 293
 294         /* add sharename in opts string as unc= parm */
 295
 296         while ((c = getopt_long (argc, argv, "afhilnrvV",
 297                          longopts, NULL)) != -1) {
 298                 switch (c) {
 299 /* No code to do the following  option yet */
 300 /*              case 'a':
 301                         ++umount_all;
 302                         break; */
 303                 case '?':
 304                 case 'h':   /* help */
 305                         umount_cifs_usage();
 306                         exit(1);
 307                 case 'n':
 308                         ++nomtab;
 309                         break;
 310                 case 'f':
 311                         flags |= MNT_FORCE;
 312                         break;
 313                 case 'l':
 314                         flags |= MNT_DETACH; /* lazy unmount */
 315                         break;
 316                 case 'e':
 317                         flags |= MNT_EXPIRE; /* gradually timeout */
 318                         break;
 319                 case 'r':
 320                         ++retry_remount;
 321                         break;
 322                 case 'v':
 323                         ++verboseflg;
 324                         break;
 325                 case 'V':
 326                         printf ("umount.cifs version: %s.%s%s\n",
 327                                 UNMOUNT_CIFS_VERSION_MAJOR,
 328                                 UNMOUNT_CIFS_VERSION_MINOR,
 329                                 UNMOUNT_CIFS_VENDOR_SUFFIX);
 330                         exit (0);
 331                 default:
 332                         printf("unknown unmount option %c\n",c);
 333                         umount_cifs_usage();
 334                         exit(1);
 335                 }
 336         }
 337
 338         /* move past the umount options */
 339         argv += optind;
 340         argc -= optind;
 341
 342         mountpoint = canonicalize(argv[0]);
 343
 344         if((argc < 1) || (argv[0] == NULL)) {
 345                 printf("\nMissing name of unmount directory\n");
 346                 umount_cifs_usage();
 347                 return -EINVAL;
 348         }
 349
 350         if(verboseflg)
 351                 printf("optind %d unmount dir %s\n",optind, mountpoint);
 352
 353         /* check if running effectively root */
 354         if(geteuid() != 0) {
 355                 printf("Trying to unmount when %s not installed suid\n",thisprogram);
 356                 if(verboseflg)
 357                         printf("euid = %d\n",geteuid());
 358                 return -EACCES;
 359         }
 360
 361         /* fixup path if needed */
 362
 363         /* Trim any trailing slashes */
 364         while ((strlen(mountpoint) > 1) &&
 365                 (mountpoint[strlen(mountpoint)-1] == '/'))
 366         {
 367                 mountpoint[strlen(mountpoint)-1] = '\0';
 368         }
 369
 370         /* make sure that this is a cifs filesystem */
 371         rc = statfs(mountpoint, &statbuf);
 372
 373         if(rc || (statbuf.f_type != CIFS_MAGIC_NUMBER)) {
 374                 printf("This utility only unmounts cifs filesystems.\n");
 375                 return -EINVAL;
 376         }
 377
 378         /* check if our uid was the one who mounted */
 379         rc = umount_check_perm(mountpoint);
 380         if (rc) {
 381                 printf("Not permitted to unmount\n");
 382                 return rc;
 383         }
 384
 385         if(umount2(mountpoint, flags)) {
 386         /* remember to kill daemon on error */
 387                 switch (errno) {
 388                 case 0:
 389                         printf("unmount failed but no error number set\n");
 390                         break;
 391                 default:
 392                         printf("unmount error %d = %s\n",errno,strerror(errno));
 393                 }
 394                 printf("Refer to the umount.cifs(8) manual page (man 8 umount.cifs)\n");
 395                 return -1;
 396         } else {
 397                 if(verboseflg)
 398                         printf("umount2 succeeded\n");
 399                 if(nomtab == 0)
 400                         remove_from_mtab(mountpoint);
 401         }
 402
 403         return 0;
 404 }
 405