/* * 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; strncpy (canonical, path, PATH_MAX); canonical[PATH_MAX] = '\0'; 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; }