source/client/smbumount.c

   1 /*
   2  *  smbumount.c
   3  *
   4  *  Copyright (C) 1995-1998 by Volker Lendecke
   5  *
   6  */
   7
   8 #define SMBMOUNT_MALLOC 1
   9
  10 #include "includes.h"
  11
  12 #include <mntent.h>
  13
  14 #include <asm/types.h>
  15 #include <asm/posix_types.h>
  16 #include <linux/smb.h>
  17 #include <linux/smb_mount.h>
  18 #include <linux/smb_fs.h>
  19
  20 /* This is a (hopefully) temporary hack due to the fact that
  21         sizeof( uid_t ) != sizeof( __kernel_uid_t ) under glibc.
  22         This may change in the future and smb.h may get fixed in the
  23         future.  In the mean time, it's ugly hack time - get over it.
  24 */
  25 #undef SMB_IOC_GETMOUNTUID
  26 #define SMB_IOC_GETMOUNTUID             _IOR('u', 1, __kernel_uid_t)
  27
  28 #ifndef O_NOFOLLOW
  29 #define O_NOFOLLOW     0400000
  30 #endif
  31
  32 static void
  33 usage(void)
  34 {
  35         printf("usage: smbumount mountpoint\n\n");
  36         printf("Please be aware that smbfs is deprecated in favor of "
  37                "cifs\n");
  38 }
  39
  40 static int
  41 umount_ok(const char *mount_point)
  42 {
  43         /* we set O_NOFOLLOW to prevent users playing games with symlinks to
  44            umount filesystems they don't own */
  45         int fid = open(mount_point, O_RDONLY|O_NOFOLLOW, 0);
  46         __kernel_uid32_t mount_uid;
  47
  48         if (fid == -1) {
  49                 fprintf(stderr, "Could not open %s: %s\n",
  50                         mount_point, strerror(errno));
  51                 return -1;
  52         }
  53
  54         if (ioctl(fid, SMB_IOC_GETMOUNTUID32, &mount_uid) != 0) {
  55                 __kernel_uid_t mount_uid16;
  56                 if (ioctl(fid, SMB_IOC_GETMOUNTUID, &mount_uid16) != 0) {
  57                         fprintf(stderr, "%s probably not smb-filesystem\n",
  58                                 mount_point);
  59                         return -1;
  60                 }
  61                 mount_uid = mount_uid16;
  62         }
  63
  64         if ((getuid() != 0)
  65             && (mount_uid != getuid())) {
  66                 fprintf(stderr, "You are not allowed to umount %s\n",
  67                         mount_point);
  68                 return -1;
  69         }
  70
  71         close(fid);
  72         return 0;
  73 }
  74
  75 /* Make a canonical pathname from PATH.  Returns a freshly malloced string.
  76    It is up the *caller* to ensure that the PATH is sensible.  i.e.
  77    canonicalize ("/dev/fd0/.") returns "/dev/fd0" even though ``/dev/fd0/.''
  78    is not a legal pathname for ``/dev/fd0''  Anything we cannot parse
  79    we return unmodified.   */
  80 static char *
  81 canonicalize (char *path)
  82 {
  83         char *canonical = (char*)malloc (PATH_MAX + 1);
  84
  85         if (!canonical) {
  86                 fprintf(stderr, "Error! Not enough memory!\n");
  87                 return NULL;
  88         }
  89
  90         if (strlen(path) > PATH_MAX) {
  91                 fprintf(stderr, "Mount point string too long\n");
  92                 return NULL;
  93         }
  94
  95         if (path == NULL)
  96                 return NULL;
  97
  98         if (realpath (path, canonical))
  99                 return canonical;
 100
 101         strncpy (canonical, path, PATH_MAX);
 102         canonical[PATH_MAX] = '\0';
 103         return canonical;
 104 }
 105
 106
 107 int
 108 main(int argc, char *argv[])
 109 {
 110         int fd;
 111         char* mount_point;
 112         struct mntent *mnt;
 113         FILE* mtab;
 114         FILE* new_mtab;
 115         TALLOC_CTX *frame = talloc_stackframe();
 116
 117         if (argc != 2) {
 118                 usage();
 119                 exit(1);
 120         }
 121
 122         if (geteuid() != 0) {
 123                 fprintf(stderr, "smbumount must be installed suid root\n");
 124                 exit(1);
 125         }
 126
 127         mount_point = canonicalize(argv[1]);
 128
 129         if (mount_point == NULL)
 130         {
 131                 exit(1);
 132         }
 133
 134         if (umount_ok(mount_point) != 0) {
 135                 exit(1);
 136         }
 137
 138         if (umount(mount_point) != 0) {
 139                 fprintf(stderr, "Could not umount %s: %s\n",
 140                         mount_point, strerror(errno));
 141                 exit(1);
 142         }
 143
 144         if ((fd = open(MOUNTED"~", O_RDWR|O_CREAT|O_EXCL, 0600)) == -1)
 145         {
 146                 fprintf(stderr, "Can't get "MOUNTED"~ lock file");
 147                 return 1;
 148         }
 149         close(fd);
 150
 151         if ((mtab = setmntent(MOUNTED, "r")) == NULL) {
 152                 fprintf(stderr, "Can't open " MOUNTED ": %s\n",
 153                         strerror(errno));
 154                 return 1;
 155         }
 156
 157 #define MOUNTED_TMP MOUNTED".tmp"
 158
 159         if ((new_mtab = setmntent(MOUNTED_TMP, "w")) == NULL) {
 160                 fprintf(stderr, "Can't open " MOUNTED_TMP ": %s\n",
 161                         strerror(errno));
 162                 endmntent(mtab);
 163                 return 1;
 164         }
 165
 166         while ((mnt = getmntent(mtab)) != NULL) {
 167                 if (strcmp(mnt->mnt_dir, mount_point) != 0) {
 168                         addmntent(new_mtab, mnt);
 169                 }
 170         }
 171
 172         endmntent(mtab);
 173
 174         if (fchmod (fileno (new_mtab), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < 0) {
 175                 fprintf(stderr, "Error changing mode of %s: %s\n",
 176                         MOUNTED_TMP, strerror(errno));
 177                 exit(1);
 178         }
 179
 180         endmntent(new_mtab);
 181
 182         if (rename(MOUNTED_TMP, MOUNTED) < 0) {
 183                 fprintf(stderr, "Cannot rename %s to %s: %s\n",
 184                         MOUNTED, MOUNTED_TMP, strerror(errno));
 185                 exit(1);
 186         }
 187
 188         if (unlink(MOUNTED"~") == -1)
 189         {
 190                 fprintf(stderr, "Can't remove "MOUNTED"~");
 191                 return 1;
 192         }
 193
 194         TALLOC_FREE(frame);
 195         return 0;
 196 }