release/src/router/samba3/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  #ifdef _SAMBA_BUILD_
  43   #include "include/version.h"
  44   #ifdef SAMBA_VERSION_VENDOR_SUFFIX
  45    #define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING"-"SAMBA_VERSION_VENDOR_SUFFIX
  46   #else
  47    #define UNMOUNT_CIFS_VENDOR_SUFFIX "-"SAMBA_VERSION_OFFICIAL_STRING
  48   #endif /* SAMBA_VERSION_OFFICIAL_STRING and SAMBA_VERSION_VENDOR_SUFFIX */
  49  #else
  50   #define UNMOUNT_CIFS_VENDOR_SUFFIX ""
  51  #endif /* _SAMBA_BUILD_ */
  52 #endif /* UNMOUNT_CIFS_VENDOR_SUFFIX */
  53
  54 #ifndef MNT_DETACH
  55 #define MNT_DETACH 0x02
  56 #endif
  57
  58 #ifndef MNT_EXPIRE
  59 #define MNT_EXPIRE 0x04
  60 #endif
  61
  62 #ifndef MOUNTED_LOCK
  63 #define MOUNTED_LOCK    "/etc/mtab~"
  64 #endif
  65 #ifndef MOUNTED_TEMP
  66 #define MOUNTED_TEMP    "/etc/mtab.tmp"
  67 #endif
  68
  69 #define CIFS_IOC_CHECKUMOUNT _IO(0xCF, 2)
  70 #define CIFS_MAGIC_NUMBER 0xFF534D42   /* the first four bytes of SMB PDU */
  71
  72 static struct option longopts[] = {
  73         { "all", 0, NULL, 'a' },
  74         { "help",0, NULL, 'h' },
  75         { "read-only", 0, NULL, 'r' },
  76         { "ro", 0, NULL, 'r' },
  77         { "verbose", 0, NULL, 'v' },
  78         { "version", 0, NULL, 'V' },
  79         { "expire", 0, NULL, 'e' },
  80         { "force", 0, 0, 'f' },
  81         { "lazy", 0, 0, 'l' },
  82         { "no-mtab", 0, 0, 'n' },
  83         { NULL, 0, NULL, 0 }
  84 };
  85
  86 const char * thisprogram;
  87 int verboseflg = 0;
  88
  89 static void umount_cifs_usage(void)
  90 {
  91         printf("\nUsage:  %s <remotetarget> <dir>\n", thisprogram);
  92         printf("\nUnmount the specified directory\n");
  93         printf("\nLess commonly used options:");
  94         printf("\n\t-r\tIf mount fails, retry with readonly remount.");
  95         printf("\n\t-n\tDo not write to mtab.");
  96         printf("\n\t-f\tAttempt a forced unmount, even if the fs is busy.");
  97         printf("\n\t-l\tAttempt lazy unmount, Unmount now, cleanup later.");
  98         printf("\n\t-v\tEnable verbose mode (may be useful for debugging).");
  99         printf("\n\t-h\tDisplay this help.");
 100         printf("\n\nOptions are described in more detail in the manual page");
 101         printf("\n\tman 8 umount.cifs\n");
 102         printf("\nTo display the version number of the cifs umount utility:");
 103         printf("\n\t%s -V\n",thisprogram);
 104         printf("\nInvoking the umount utility on cifs mounts, can execute");
 105         printf(" /sbin/umount.cifs (if present and umount -i is not specified.\n");
 106 }
 107
 108 static int umount_check_perm(char * dir)
 109 {
 110         int fileid;
 111         int rc;
 112
 113         /* allow root to unmount, no matter what */
 114         if(getuid() == 0)
 115                 return 0;
 116
 117         /* presumably can not chdir into the target as we do on mount */
 118         fileid = open(dir, O_RDONLY | O_DIRECTORY | O_NOFOLLOW, 0);
 119         if(fileid == -1) {
 120                 if(verboseflg)
 121                         printf("error opening mountpoint %d %s",errno,strerror(errno));
 122                 return errno;
 123         }
 124
 125         rc = ioctl(fileid, CIFS_IOC_CHECKUMOUNT, NULL);
 126
 127         if(verboseflg)
 128                 printf("ioctl returned %d with errno %d %s\n",rc,errno,strerror(errno));
 129
 130         if(rc == ENOTTY) {
 131                 printf("user unmounting via %s is an optional feature of",thisprogram);
 132                 printf(" the cifs filesystem driver (cifs.ko)");
 133                 printf("\n\tand requires cifs.ko version 1.32 or later\n");
 134         } else if (rc > 0)
 135                 printf("user unmount of %s failed with %d %s\n",dir,errno,strerror(errno));
 136         close(fileid);
 137
 138         return rc;
 139 }
 140
 141 int lock_mtab(void)
 142 {
 143         int rc;
 144
 145         rc = mknod(MOUNTED_LOCK , 0600, 0);
 146         if(rc == -1)
 147                 printf("\ngetting lock file %s failed with %s\n",MOUNTED_LOCK,
 148                                 strerror(errno));
 149
 150         return rc;
 151
 152 }
 153
 154 void unlock_mtab(void)
 155 {
 156         unlink(MOUNTED_LOCK);
 157 }
 158
 159 int remove_from_mtab(char * mountpoint)
 160 {
 161         int rc;
 162         int num_matches;
 163         FILE * org_fd;
 164         FILE * new_fd;
 165         struct mntent * mount_entry;
 166
 167         /* Do we need to check if it is a symlink to e.g. /proc/mounts
 168         in which case we probably do not want to update it? */
 169
 170         /* Do we first need to check if it is writable? */
 171
 172         if (lock_mtab()) {
 173                 printf("Mount table locked\n");
 174                 return -EACCES;
 175         }
 176
 177         if(verboseflg)
 178                 printf("attempting to remove from mtab\n");
 179
 180         org_fd = setmntent(MOUNTED, "r");
 181
 182         if(org_fd == NULL) {
 183                 printf("Can not open %s\n",MOUNTED);
 184                 unlock_mtab();
 185                 return -EIO;
 186         }
 187
 188         new_fd = setmntent(MOUNTED_TEMP,"w");
 189         if(new_fd == NULL) {
 190                 printf("Can not open temp file %s", MOUNTED_TEMP);
 191                 endmntent(org_fd);
 192                 unlock_mtab();
 193                 return -EIO;
 194         }
 195
 196         /* BB fix so we only remove the last entry that matches BB */
 197         num_matches = 0;
 198         while((mount_entry = getmntent(org_fd)) != NULL) {
 199                 if(strcmp(mount_entry->mnt_dir, mountpoint) == 0) {
 200                         num_matches++;
 201                 }
 202         }
 203         if(verboseflg)
 204                 printf("%d matching entries in mount table\n", num_matches);
 205
 206         /* Is there a better way to seek back to the first entry in mtab? */
 207         endmntent(org_fd);
 208         org_fd = setmntent(MOUNTED, "r");
 209
 210         if(org_fd == NULL) {
 211                 printf("Can not open %s\n",MOUNTED);
 212                 unlock_mtab();
 213                 return -EIO;
 214         }
 215
 216         while((mount_entry = getmntent(org_fd)) != NULL) {
 217                 if(strcmp(mount_entry->mnt_dir, mountpoint) != 0) {
 218                         addmntent(new_fd, mount_entry);
 219                 } else {
 220                         if(num_matches != 1) {
 221                                 addmntent(new_fd, mount_entry);
 222                                 num_matches--;
 223                         } else if(verboseflg)
 224                                 printf("entry not copied (ie entry is removed)\n");
 225                 }
 226         }
 227
 228         if(verboseflg)
 229                 printf("done updating tmp file\n");
 230         rc = fchmod (fileno (new_fd), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH);
 231         if(rc < 0) {
 232                 printf("error %s changing mode of %s\n", strerror(errno),
 233                         MOUNTED_TEMP);
 234         }
 235         endmntent(new_fd);
 236
 237         rc = rename(MOUNTED_TEMP, MOUNTED);
 238
 239         if(rc < 0) {
 240                 printf("failure %s renaming %s to %s\n",strerror(errno),
 241                         MOUNTED_TEMP, MOUNTED);
 242                 unlock_mtab();
 243                 return -EIO;
 244         }
 245
 246         unlock_mtab();
 247
 248         return rc;
 249 }
 250
 251 int main(int argc, char ** argv)
 252 {
 253         int c;
 254         int rc;
 255         int flags = 0;
 256         int nomtab = 0;
 257         int retry_remount = 0;
 258         struct statfs statbuf;
 259         char * mountpoint;
 260
 261         if(argc && argv) {
 262                 thisprogram = argv[0];
 263         } else {
 264                 umount_cifs_usage();
 265                 return -EINVAL;
 266         }
 267
 268         if(argc < 2) {
 269                 umount_cifs_usage();
 270                 return -EINVAL;
 271         }
 272
 273         if(thisprogram == NULL)
 274                 thisprogram = "umount.cifs";
 275
 276         /* add sharename in opts string as unc= parm */
 277
 278         while ((c = getopt_long (argc, argv, "afhilnrvV",
 279                          longopts, NULL)) != -1) {
 280                 switch (c) {
 281 /* No code to do the following  option yet */
 282 /*              case 'a':
 283                         ++umount_all;
 284                         break; */
 285                 case '?':
 286                 case 'h':   /* help */
 287                         umount_cifs_usage();
 288                         exit(1);
 289                 case 'n':
 290                         ++nomtab;
 291                         break;
 292                 case 'f':
 293                         flags |= MNT_FORCE;
 294                         break;
 295                 case 'l':
 296                         flags |= MNT_DETACH; /* lazy unmount */
 297                         break;
 298                 case 'e':
 299                         flags |= MNT_EXPIRE; /* gradually timeout */
 300                         break;
 301                 case 'r':
 302                         ++retry_remount;
 303                         break;
 304                 case 'v':
 305                         ++verboseflg;
 306                         break;
 307                 case 'V':
 308                         printf ("umount.cifs version: %s.%s%s\n",
 309                                 UNMOUNT_CIFS_VERSION_MAJOR,
 310                                 UNMOUNT_CIFS_VERSION_MINOR,
 311                                 UNMOUNT_CIFS_VENDOR_SUFFIX);
 312                         exit (0);
 313                 default:
 314                         printf("unknown unmount option %c\n",c);
 315                         umount_cifs_usage();
 316                         exit(1);
 317                 }
 318         }
 319
 320         /* move past the umount options */
 321         argv += optind;
 322         argc -= optind;
 323
 324         mountpoint = argv[0];
 325
 326         if((argc < 1) || (argv[0] == NULL)) {
 327                 printf("\nMissing name of unmount directory\n");
 328                 umount_cifs_usage();
 329                 return -EINVAL;
 330         }
 331
 332         if(verboseflg)
 333                 printf("optind %d unmount dir %s\n",optind, mountpoint);
 334
 335         /* check if running effectively root */
 336         if(geteuid() != 0) {
 337                 printf("Trying to unmount when %s not installed suid\n",thisprogram);
 338                 if(verboseflg)
 339                         printf("euid = %d\n",geteuid());
 340                 return -EACCES;
 341         }
 342
 343         /* fixup path if needed */
 344
 345         /* make sure that this is a cifs filesystem */
 346         rc = statfs(mountpoint, &statbuf);
 347
 348         if(rc || (statbuf.f_type != CIFS_MAGIC_NUMBER)) {
 349                 printf("This utility only unmounts cifs filesystems.\n");
 350                 return -EINVAL;
 351         }
 352
 353         /* check if our uid was the one who mounted */
 354         rc = umount_check_perm(mountpoint);
 355         if (rc) {
 356                 printf("Not permitted to unmount\n");
 357                 return rc;
 358         }
 359
 360         if(umount2(mountpoint, flags)) {
 361         /* remember to kill daemon on error */
 362                 switch (errno) {
 363                 case 0:
 364                         printf("unmount failed but no error number set\n");
 365                         break;
 366                 default:
 367                         printf("unmount error %d = %s\n",errno,strerror(errno));
 368                 }
 369                 printf("Refer to the umount.cifs(8) manual page (man 8 umount.cifs)\n");
 370                 return -1;
 371         } else {
 372                 if(verboseflg)
 373                         printf("umount2 succeeded\n");
 374                 if(nomtab == 0)
 375                         remove_from_mtab(mountpoint);
 376         }
 377
 378         return 0;
 379 }
 380