[PATCH]: Cygwin: Allow sshd to switch user context without password

[mouring at etoh.eviladmin.org]

Applied.  Along with the document/ssh-host-config update.

Thanks.

On Wed, 11 Jul 2001, Corinna Vinschen wrote:

> Hi,
>
> the following patch checks if OpenSSH is running under a Cygwin
> version >= 1.3.2 which allows switching user context without password.
> Otherwise sshd allows changing the user context only if password
> authentication is used as it was before.
>
> Corinna
>
> Index: openbsd-compat/bsd-cygwin_util.c
> ===================================================================
> RCS file: /cvs/openssh_cvs/openbsd-compat/bsd-cygwin_util.c,v
> retrieving revision 1.4
> diff -u -p -r1.4 bsd-cygwin_util.c
> --- openbsd-compat/bsd-cygwin_util.c	2001/04/13 14:28:42	1.4
> +++ openbsd-compat/bsd-cygwin_util.c	2001/07/11 20:35:40
> @@ -21,10 +21,14 @@ RCSID("$Id: bsd-cygwin_util.c,v 1.4 2001
>
>  #include <fcntl.h>
>  #include <stdlib.h>
> +#include <sys/utsname.h>
>  #include <sys/vfs.h>
>  #include <windows.h>
>  #define is_winnt       (GetVersion() < 0x80000000)
>
> +#define ntsec_on(c)	((c) && strstr((c),"ntsec") && !strstr((c),"nontsec"))
> +#define ntea_on(c)	((c) && strstr((c),"ntea") && !strstr((c),"nontea"))
> +
>  #if defined(open) && open == binary_open
>  # undef open
>  #endif
> @@ -61,12 +65,34 @@ int check_nt_auth(int pwd_authenticated,
>  	* context on NT systems is the password authentication. So
>  	* we deny all requsts for changing the user context if another
>  	* authentication method is used.
> -	* This may change in future when a special openssh
> -	* subauthentication package is available.
> +	*
> +	* This doesn't apply to Cygwin versions >= 1.3.2 anymore which
> +	* uses the undocumented NtCreateToken() call to create a user
> +	* token if the process has the appropriate privileges and if
> +	* CYGWIN ntsec setting is on.
>  	*/
> -	if (is_winnt && !pwd_authenticated && geteuid() != uid)
> -		return 0;
> -
> +	static int has_create_token = -1;
> +
> +	if (is_winnt) {
> +		if (has_create_token < 0) {
> +			struct utsname uts;
> +		        int major_high = 0, major_low = 0, minor = 0;
> +			char *cygwin = getenv("CYGWIN");
> +
> +			has_create_token = 0;
> +			if (ntsec_on(cygwin) && !uname(&uts)) {
> +				sscanf(uts.release, "%d.%d.%d",
> +				       &major_high, &major_low, &minor);
> +				if (major_high > 1 ||
> +				    (major_high == 1 && (major_low > 3 ||
> +				     (major_low == 3 && minor >= 2))))
> +					has_create_token = 1;
> +			}
> +		}
> +		if (has_create_token < 1 &&
> +		    !pwd_authenticated && geteuid() != uid)
> +			return 0;
> +	}
>  	return 1;
>  }
>
> @@ -82,12 +108,9 @@ int check_ntsec(const char *filename)
>  		return 0;
>
>  	/* Evaluate current CYGWIN settings. */
> -	if ((cygwin = getenv("CYGWIN")) != NULL) {
> -		if (strstr(cygwin, "ntea") && !strstr(cygwin, "nontea"))
> -			allow_ntea = 1;
> -		if (strstr(cygwin, "ntsec") && !strstr(cygwin, "nontsec"))
> -			allow_ntsec = 1;
> -	}
> +	cygwin = getenv("CYGWIN");
> +	allow_ntea = ntea_on(cygwin);
> +	allow_ntsec = ntsec_on(cygwin);
>
>  	/*
>  	 * `ntea' is an emulation of POSIX attributes. It doesn't support
>
> --
> Corinna Vinschen
> Cygwin Developer
> Red Hat, Inc.
> mailto:vinschen at redhat.com
>