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/*
* smbumount.c
*
* Copyright (C) 1995-1998 by Volker Lendecke
*
*/
#include "includes.h"
#include <mntent.h>
#include <asm/types.h>
#include <asm/posix_types.h>
#include <linux/smb.h>
#include <linux/smb_mount.h>
#include <linux/smb_fs.h>
/* This is a (hopefully) temporary hack due to the fact that
sizeof( uid_t ) != sizeof( __kernel_uid_t ) under glibc.
This may change in the future and smb.h may get fixed in the
future. In the mean time, it's ugly hack time - get over it.
*/
#undef SMB_IOC_GETMOUNTUID
#define SMB_IOC_GETMOUNTUID _IOR('u', 1, __kernel_uid_t)
#ifndef O_NOFOLLOW
#define O_NOFOLLOW 0400000
#endif
static void
usage(void)
{
printf("usage: smbumount mountpoint\n");
}
static int
umount_ok(const char *mount_point)
{
/* we set O_NOFOLLOW to prevent users playing games with symlinks to
umount filesystems they don't own */
int fid = open(mount_point, O_RDONLY|O_NOFOLLOW, 0);
__kernel_uid_t mount_uid;
if (fid == -1) {
fprintf(stderr, "Could not open %s: %s\n",
mount_point, strerror(errno));
return -1;
}
if (ioctl(fid, SMB_IOC_GETMOUNTUID, &mount_uid) != 0) {
fprintf(stderr, "%s probably not smb-filesystem\n",
mount_point);
return -1;
}
if ((getuid() != 0)
&& (mount_uid != getuid())) {
fprintf(stderr, "You are not allowed to umount %s\n",
mount_point);
return -1;
}
close(fid);
return 0;
}
/* Make a canonical pathname from PATH. Returns a freshly malloced string.
It is up the *caller* to ensure that the PATH is sensible. i.e.
canonicalize ("/dev/fd0/.") returns "/dev/fd0" even though ``/dev/fd0/.''
is not a legal pathname for ``/dev/fd0'' Anything we cannot parse
we return unmodified. */
static char *
canonicalize (char *path)
{
char *canonical = malloc (PATH_MAX + 1);
if (!canonical) {
fprintf(stderr, "Error! Not enough memory!\n");
return NULL;
}
if (strlen(path) > PATH_MAX) {
fprintf(stderr, "Mount point string too long\n");
return NULL;
}
if (path == NULL)
return NULL;
if (realpath (path, canonical))
return canonical;
pstrcpy (canonical, path);
return canonical;
}
int
main(int argc, char *argv[])
{
int fd;
char* mount_point;
struct mntent *mnt;
FILE* mtab;
FILE* new_mtab;
if (argc != 2) {
usage();
exit(1);
}
if (geteuid() != 0) {
fprintf(stderr, "smbumount must be installed suid root\n");
exit(1);
}
mount_point = canonicalize(argv[1]);
if (mount_point == NULL)
{
exit(1);
}
if (umount_ok(mount_point) != 0) {
exit(1);
}
if (umount(mount_point) != 0) {
fprintf(stderr, "Could not umount %s: %s\n",
mount_point, strerror(errno));
exit(1);
}
if ((fd = open(MOUNTED"~", O_RDWR|O_CREAT|O_EXCL, 0600)) == -1)
{
fprintf(stderr, "Can't get "MOUNTED"~ lock file");
return 1;
}
close(fd);
if ((mtab = setmntent(MOUNTED, "r")) == NULL) {
fprintf(stderr, "Can't open " MOUNTED ": %s\n",
strerror(errno));
return 1;
}
#define MOUNTED_TMP MOUNTED".tmp"
if ((new_mtab = setmntent(MOUNTED_TMP, "w")) == NULL) {
fprintf(stderr, "Can't open " MOUNTED_TMP ": %s\n",
strerror(errno));
endmntent(mtab);
return 1;
}
while ((mnt = getmntent(mtab)) != NULL) {
if (strcmp(mnt->mnt_dir, mount_point) != 0) {
addmntent(new_mtab, mnt);
}
}
endmntent(mtab);
if (fchmod (fileno (new_mtab), S_IRUSR|S_IWUSR|S_IRGRP|S_IROTH) < 0) {
fprintf(stderr, "Error changing mode of %s: %s\n",
MOUNTED_TMP, strerror(errno));
exit(1);
}
endmntent(new_mtab);
if (rename(MOUNTED_TMP, MOUNTED) < 0) {
fprintf(stderr, "Cannot rename %s to %s: %s\n",
MOUNTED, MOUNTED_TMP, strerror(errno));
exit(1);
}
if (unlink(MOUNTED"~") == -1)
{
fprintf(stderr, "Can't remove "MOUNTED"~");
return 1;
}
return 0;
}
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