check_login in loginutils/login.c (was Re: [BusyBox] Re: login buggy also in 1.00pre5)

[Friedrich Lobenstock]

Charlie Brady wrote on 06.01.2004 23:22 MET:
> On Tue, 6 Jan 2004, Tito wrote:
> 
> 
>>>>	if ( check_nologin ( pw-> pw_uid == 0 ))
>>>>		return EXIT_FAILURE;
> 
> ...
> 
>>maybe something like :
>> 	if ( check_nologin ( (pw-> pw_uid == 0) ) == 1)
>> 		return EXIT_FAILURE;
>>would be easier to understand for the non-gurus. ;-)
> 
> 
> But that might mean something different (the internals of 
> check_nologin() will say).
> 
> Would you be happier with
> 
> if (check_nologin(!pw->pw_uid))
>     return EXIT_FAILURE;

How about the patch below? It calls check_nologin for a user-id
which I think is more clear and let me show you that we even
reduce code size:

# sed -e "/^$/d" -e "/^#/d" .config
HAVE_DOT_CONFIG=y
CONFIG_FEATURE_BUFFERS_GO_IN_BSS=y
CONFIG_FEATURE_VERBOSE_USAGE=y
CONFIG_FEATURE_DEVPTS=y
EXTRA_CFLAGS_OPTIONS=""
PREFIX="./_install"
CONFIG_LOGIN=y
CONFIG_FEATURE_SECURETTY=y
CONFIG_FEATURE_SH_IS_NONE=y

* without this patch applied (binary stripped):

   # ls -al busybox-1.00-pre5/busybox
   -rwxr-xr-x    1 fl       users       13424 2004-01-07 00:09 busybox-1.00-pre5/busybox*

* with this patch applied (binary stripped):

   # ls -al busybox-1.00-pre5/busybox
   -rwxr-xr-x    1 fl       users       13392 2004-01-07 00:13 busybox-1.00-pre5/busybox*


Difference: 32 Bytes (because we do one comparision less than before)
[ note: result valid for the CRIS architecture, numbers might differ on other arch ]

--- busybox-1.00-pre5/loginutils/login.c.org	2004-01-06 23:33:24.000000000 +0100
+++ busybox-1.00-pre5/loginutils/login.c	2004-01-06 23:35:01.000000000 +0100
@@ -37,7 +37,7 @@
  #define USERNAME_SIZE 32


-static int check_nologin ( int amroot );
+static int check_nologin ( int uid );

  #if defined CONFIG_FEATURE_SECURETTY
  static int check_tty ( const char *tty );
@@ -217,7 +217,7 @@
  	}
  		
  	alarm ( 0 );
-	if ( check_nologin ( pw-> pw_uid == 0 ))
+	if ( check_nologin ( pw-> pw_uid ))
  		return EXIT_FAILURE;

  #ifdef CONFIG_FEATURE_U_W_TMP
@@ -315,7 +315,7 @@
  }


-static int check_nologin ( int amroot )
+static int check_nologin ( int uid )
  {
  	if ( access ( bb_path_nologin_file, F_OK ) == 0 ) {
  		FILE *fp;
@@ -330,7 +330,7 @@
  		} else {
  			puts ( "\r\nSystem closed for routine maintenance.\r" );
  		}
-		if ( !amroot )
+		if ( uid ) /* !root */
  			return 1;
  			
  		puts ( "\r\n[Disconnect bypassed -- root login allowed.]\r" );


-- 
MfG / Regards
Friedrich Lobenstock