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    SubjectRe: [PATCH] Smack: fix domain transfer issues


    On Wed, 28 Sep 2011, Stephen Smalley wrote:
    > Did I miss something or did you find a rationale for using bprm->unsafe
    > in this manner? It isn't private to your security module yet you are
    > claiming a bit for your own private use without reserving it in any way
    > globally (consider implications for any future stacking), and setting
    > new bits in it will have side effects on the capabilities logic. I
    > already mentioned this on your first patch and you seemed to acknowledge
    > it then. Pass it via bprm->cred->security if you need to pass it as a
    > flag, or re-test the condition in the secureexec hook otherwise.

    You got your point. I'll add smk_flags field to
    the struct task_smack (our task security blob).

    > Why not just:
    > if (bprm->unsafe)
    > return -EPERM;
    > if you aren't going to distinguish them via permission checks or
    > anything?

    I guess my purpose was to leave those visible because
    plan is to add permission checks at least for the
    ptrace case in the future. Now that I think of it,
    it does not justify their existence in the code.
    I'll revise this.

    Even in the current form, there should be check that
    you described to protect this code against situation
    where new LSM_UNSAFE flag is added and support has not
    yet been implemented to Smack.

    >
    > I take it you've decided you don't need any of the other checks or
    > sanitization applied by SELinux?

    MNT_NOSUID should be checked. Also, I'll plan to
    implement permission check for ptrace but in the
    scope of this patch.

    Thanks for informative reply!

    /Jarkko


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