Re: Make coretutils work better with SELinux.

[Pádraig Brady]

On 10/30/2012 02:43 PM, Daniel J Walsh wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> For some reason I could not get git to take more then a one line comment.
> This is the comment I was trying to add.
>
>
>          build: Change -Z opt w/out arg label target with default label
>
>          The -Z without argument will ask SELinux what the default label of the 
> i
>          dest object should be and then attempt to change it.
>
>          The -Z with an optional context will create all targets with the
>          optional label. This is still supported for backwards compatability.
>
>          The mv command does not support the optional argument.
>
>
> BTW, it looks like coreutils has removed -ZCONTEXT from cp, if I had my
> druthers, I would make all commands just use -Z and not allow the optional
> arg.  Then -Z would just set the default label.  I would bet that no one in
> history has executed a command like:
>
> mkdir -Zunconfined_u:object_r:httpd_user_content_t:s0 ~/myweb

Thanks for the update.

Short options with optional args are very problematic.
It would mean `cp -aZ` was OK while `cp -Za` was not etc.
Also in Red Hat distros, `cp -Z` requires an arg, so changing that
would mean that older scripts that used `cp -Z blah...` would
break with newer cp, as a space is not allowed for optional args.

For that reason I would keep -Z and --context as is,
but deprecate them for the commands that set a context,
and add a new --new-context option that could take the optional arg:

In that way, -Z can continue to be used as it is commonly
with commands like `ls` etc. to _read_ the context.
Whereas the currently rare form of {mkdir,cp,install} -Z context:to_write
can be deprecated in favor of:

    --new-context[=CONTEXT]
       set security context to CONTEXT, or set context to
       the system default for the destination.

I'm mildly in favor of introducing --new-context, over just
making --context take an optional arg (so that it's obvious
a new context is being set, rather than one being copied),
but I'm strongly against making -Z take an optional arg.

cheers,
Pádraig.