source/client/smbumount.c

   1 /*
   2  *  smbumount.c
   3  *
   4  *  Copyright (C) 1995-1998 by Volker Lendecke
   5  *
   6  */
   7
   8 #include "includes.h"
   9
  10 #include <mntent.h>
  11
  12 #include <asm/types.h>
  13 #include <asm/posix_types.h>
  14 #include <linux/smb.h>
  15 #include <linux/smb_mount.h>
  16 #include <linux/smb_fs.h>
  17
  18 /* This is a (hopefully) temporary hack due to the fact that
  19         sizeof( uid_t ) != sizeof( __kernel_uid_t ) under glibc.
  20         This may change in the future and smb.h may get fixed in the
  21         future.  In the mean time, it's ugly hack time - get over it.
  22 */
  23 #undef SMB_IOC_GETMOUNTUID
  24 #define SMB_IOC_GETMOUNTUID             _IOR('u', 1, __kernel_uid_t)
  25
  26 static char *progname;
  27
  28 static void
  29 usage(void)
  30 {
  31         printf("usage: %s mount-point\n", progname);
  32 }
  33
  34 static int
  35 umount_ok(const char *mount_point)
  36 {
  37         int fid = open(mount_point, O_RDONLY, 0);
  38         __kernel_uid_t mount_uid;
  39
  40         if (fid == -1) {
  41                 fprintf(stderr, "Could not open %s: %s\n",
  42                         mount_point, strerror(errno));
  43                 return -1;
  44         }
  45
  46         if (ioctl(fid, SMB_IOC_GETMOUNTUID, &mount_uid) != 0) {
  47                 fprintf(stderr, "%s probably not smb-filesystem\n",
  48                         mount_point);
  49                 return -1;
  50         }
  51
  52         if (   (getuid() != 0)
  53             && (mount_uid != getuid())) {
  54                 fprintf(stderr, "You are not allowed to umount %s\n",
  55                         mount_point);
  56                 return -1;
  57         }
  58
  59         close(fid);
  60         return 0;
  61 }
  62
  63 /* Make a canonical pathname from PATH.  Returns a freshly malloced string.
  64    It is up the *caller* to ensure that the PATH is sensible.  i.e.
  65    canonicalize ("/dev/fd0/.") returns "/dev/fd0" even though ``/dev/fd0/.''
  66    is not a legal pathname for ``/dev/fd0.''  Anything we cannot parse
  67    we return unmodified.   */
  68 char *
  69 canonicalize (char *path)
  70 {
  71         char *canonical = malloc (PATH_MAX + 1);
  72
  73         if (strlen(path) > PATH_MAX)
  74         {
  75                 fprintf(stderr, "Mount point string too long\n");
  76                 return NULL;
  77         }
  78
  79         if (path == NULL)
  80                 return NULL;
  81
  82         if (realpath (path, canonical))
  83                 return canonical;
  84
  85         pstrcpy (canonical, path);
  86         return canonical;
  87 }
  88
  89
  90 int
  91 main(int argc, char *argv[])
  92 {
  93         int fd;
  94
  95         char* mount_point;
  96
  97         struct mntent *mnt;
  98         FILE* mtab;
  99         FILE* new_mtab;
 100
 101         progname = argv[0];
 102
 103         if (argc != 2) {
 104                 usage();
 105                 exit(1);
 106         }
 107
 108         if (geteuid() != 0) {
 109                 fprintf(stderr, "%s must be installed suid root\n", progname);
 110                 exit(1);
 111         }
 112
 113         mount_point = canonicalize(argv[1]);
 114
 115         if (mount_point == NULL)
 116         {
 117                 exit(1);
 118         }
 119
 120         if (umount_ok(mount_point) != 0) {
 121                 exit(1);
 122         }
 123
 124         if (umount(mount_point) != 0) {
 125                 fprintf(stderr, "Could not umount %s: %s\n",
 126                         mount_point, strerror(errno));
 127                 exit(1);
 128         }
 129
 130         if ((fd = open(MOUNTED"~", O_RDWR|O_CREAT|O_EXCL, 0600)) == -1)
 131         {
 132                 fprintf(stderr, "Can't get "MOUNTED"~ lock file");
 133                 return 1;
 134         }
 135         close(fd);
 136
 137         if ((mtab = setmntent(MOUNTED, "r")) == NULL) {
 138                 fprintf(stderr, "Can't open " MOUNTED ": %s\n",
 139                         strerror(errno));
 140                 return 1;
 141         }
 142
 143 #define MOUNTED_TMP MOUNTED".tmp"
 144
 145         if ((new_mtab = setmntent(MOUNTED_TMP, "w")) == NULL) {
 146                 fprintf(stderr, "Can't open " MOUNTED_TMP ": %s\n",
 147                         strerror(errno));
 148                 endmntent(mtab);
 149                 return 1;
 150         }
 151
 152         while ((mnt = getmntent(mtab)) != NULL) {
 153                 if (strcmp(mnt->mnt_dir, mount_point) != 0) {
 154                         addmntent(new_mtab, mnt);
 155                 }
 156         }
 157
 158         endmntent(mtab);
 159
 160         if (fchmod (fileno (new_mtab), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < 0) {
 161                 fprintf(stderr, "Error changing mode of %s: %s\n",
 162                         MOUNTED_TMP, strerror(errno));
 163                 exit(1);
 164         }
 165
 166         endmntent(new_mtab);
 167
 168         if (rename(MOUNTED_TMP, MOUNTED) < 0) {
 169                 fprintf(stderr, "Cannot rename %s to %s: %s\n",
 170                         MOUNTED, MOUNTED_TMP, strerror(errno));
 171                 exit(1);
 172         }
 173
 174         if (unlink(MOUNTED"~") == -1)
 175         {
 176                 fprintf(stderr, "Can't remove "MOUNTED"~");
 177                 return 1;
 178         }
 179
 180         return 0;
 181 }