Re: suidpid( UID, credential? ) ? secure IPC?

H. Peter Anvin (hpa@transmeta.com)
7 Oct 1997 06:03:25 GMT

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Followup to: <199710061649.MAA21893@dcl.MIT.EDU>
By author: "Theodore Y. Ts'o" <tytso@MIT.EDU>
In newsgroup: linux.dev.kernel
>
> This allows you to do all sorts of very interesting things all in
> userspace, without needing extra special-purpose system calls and
> without requiring an IPC mechanism. It does require a kernel
> context-switch to enter and leave a PSL, but if it's done properly, that
> should be the only overhead.
>

Actually, at least on the i386 you can do a single context switch
straight into the PSL.

The danger is that it is a lot harder to write a safe PSL than it is
to write a safe setuid program, and we all know how easy that is...

-hpa

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