linux-kernel - Re: [PATCH] Smack: Use secureexec with SMACK64EXEC

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Message-ID: <CADjiTvCQp5EHigC60YD5HzshzaUaKWKhPc95WC2sBAjFcGmUUQ@mail.gmail.com>
Date:	Thu, 22 Sep 2011 10:25:44 +0300
From:	"Sakkinen, Jarkko" <jarkko.sakkinen@...el.com>
To:	Stephen Smalley <sds@...ho.nsa.gov>
Cc:	Casey Schaufler <casey@...aufler-ca.com>,
	linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: Re: [PATCH] Smack: Use secureexec with SMACK64EXEC

On Wed, Sep 21, 2011 at 8:15 PM, Stephen Smalley <sds@...ho.nsa.gov> wrote:
> bprm->unsafe isn't private to your security module, unlike e.g.
> bprm->cred->security.  And it isn't intended to indicate that a
> secureexec is being performed, but instead as an indicator that a
> credential-changing exec may be unsafe.  Which you presently ignore.
> Defining and setting a new flag in it will have interesting side
> effects, e.g. consider cap_bprm_secureexec, not to mention being a
> layering violation and a source of future conflicts.
>
> Why can't your bprm_secureexec hook just test isp->smk_task directly?
> It can reach it from the bprm.  Or if you don't like testing it twice,
> then you could always add a flag to your struct referenced by
> bprm->cred->security, i.e. the smack_task struct.

Thank you. You're absolutely right on this and yes, I can
safely just use isp->smk_task. No need for that flag.

BTW, do you know why AppArmor does use similar flag
AA_SECURE_X_NEEDED?

> BTW, there is a lot more to do if you want SMACK64EXEC to be safe.

Can you open up this a bit?

/Jarkko
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