linux-kernel - Re: [PATCH] x86: prevent binaries from making system calls using the wrong syscall interface

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Message-ID: <20080807074920.GC16610@atrey.karlin.mff.cuni.cz>
Date:	Thu, 7 Aug 2008 09:49:20 +0200
From:	Pavel Machek <pavel@...e.cz>
To:	Michael Davidson <md@...gle.com>
Cc:	mingo@...hat.com, tglx@...utronix.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: prevent binaries from making system calls using the wrong syscall interface

> Prevent binaries from making system calls using other than one
> of the "normal" system call interfaces for that binary type.
> 
> Currently there is nothing to prevent 64 bit binaries from
> attempting to make system calls using the 32 bit system call
> interfaces and vice versa.

I thought this was a feature?

> Index: linux-2.6.26.2/arch/x86/ia32/ia32entry.S
> ===================================================================
> --- linux-2.6.26.2.orig/arch/x86/ia32/ia32entry.S	2008-08-06 09:19:01.000000000 -0700
> +++ linux-2.6.26.2/arch/x86/ia32/ia32entry.S	2008-08-06 13:34:54.566992000 -0700
> @@ -123,6 +123,8 @@
>   	.quad 1b,ia32_badarg
>   	.previous	
>  	GET_THREAD_INFO(%r10)
> +	testl  $_TIF_IA32,threadinfo_flags(%r10)
> +	jz     ia32_bad_abi
>  	orl    $TS_COMPAT,threadinfo_status(%r10)
>  	testl  $(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SECCOMP),threadinfo_flags(%r10)
>  	CFI_REMEMBER_STATE

...and slowing down all syscalls for this is certainly bad idea.
									Pavel
-- 
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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