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SubjectRe: Subject: Re: ext3 to include capabilities?
"Albert D. Cahalan" wrote:
>
> G. Sumner Hayes writes:
> > Albert Cahalan <acahalan@cs.uml.edu> wrote:
>
> >> 1. Put capabilities information in the executable header.
> >> 2. Mark the executable setuid root.
> >> 3. Have the kernel check for #1 if #2, and prefer #1 if present.
> >
> > Of course, you've completely busted up security.
>
> Nope, think about the system a bit more. It isn't so stupid.
>
> if(setuid){
> if(root_owned && cap_header) use_cap_header();
> else use_setuid_bit();
> }
>


But why only use user 'root'.

In my understanding with the capabilities sheme, any user could receive
specifique (permanent/or not) privs from the apropriate sysadmin. these
privs will be stored somewhere on the system (probably not in passwd,
but
like shadow passwords, in a separate safe file).

allow suid to any user when checking for the capabilities of the file,
but
check if that user is allowed that capability.

now make an apropriate 'super exec virtual user' with any uid, and
give him all privs you allow on you suid executables.

now for the next several years until all systems have cached up with
this
sheme, this 'super exec virtual user' will probably be root. however
later
you can try to reduce this users capabilities.

Comments ?

Ernest

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