[PATCH] deluser: check if specified home is a directory before removing it

[Tito]

On 6/9/20 12:44 PM, soeren at soeren-tempel.net wrote:
> From: Sören Tempel <soeren+git at soeren-tempel.net>
> 
> On Alpine, some users use /dev/null as a home directory. When removing
> such a user with `deluser --remove-home` this causes the /dev/null
> device file to be removed which is undesirable. To prevent this pitfall,
> check if the home directory specified for the user is an actual
> directory (or a symlink to a directory).
> 
> Implementations of similar tools for other operating systems also
> implement such checks. For instance, the OpenBSD rmuser(1)
> implementation [0].
> 
> [0]: https://github.com/openbsd/src/blob/b69faa6c70c5bfcfdddc6138cd8e0ee18cc15b03/usr.sbin/adduser/rmuser.perl#L143-L151
> ---
>  loginutils/deluser.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/loginutils/deluser.c b/loginutils/deluser.c
> index 56bc7eaa6..633958b9c 100644
> --- a/loginutils/deluser.c
> +++ b/loginutils/deluser.c
> @@ -99,8 +99,16 @@ int deluser_main(int argc, char **argv)
>  			pfile = bb_path_passwd_file;
>  			if (ENABLE_FEATURE_SHADOWPASSWDS)
>  				sfile = bb_path_shadow_file;
> -			if (opt_delhome)
> -				remove_file(pw->pw_dir, FILEUTILS_RECUR);
> +			if (opt_delhome) {
> +				struct stat st;
> +
> +				/* Make sure home is an actual directory before
> +				 * removing it (e.g. users with /dev/null as home) */
> +				if (stat(pw->pw_dir, &st))
> +					bb_error_msg_and_die("can't stat '%s'", pw->pw_dir);
				Hi, use
                                xstat(pw->pw_dir, &st);
> +				if (S_ISDIR(st.st_mode))
> +					remove_file(pw->pw_dir, FILEUTILS_RECUR);
> +			}
>  		} else {
>  			struct group *gr;
>   do_delgroup:

Ciao,
Tito