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    SubjectRe: [RFC] c/r: prctl: Add ability to set new mm_struct::exe_file v3
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    On Thu, Mar 8, 2012 at 12:02 PM, Andy Lutomirski <luto@amacapital.net> wrote:
    > On Thu, Mar 8, 2012 at 11:40 AM, Cyrill Gorcunov <gorcunov@openvz.org> wrote:
    >> On Thu, Mar 08, 2012 at 11:31:58AM -0800, Kees Cook wrote:
    >> ...
    >>> > +       err = -EACCES;
    >>> > +       if (!S_ISREG(dentry->d_inode->i_mode)   ||
    >>> > +           exe_file->f_path.mnt->mnt_flags & MNT_NOEXEC)
    >>> > +               goto exit;
    >>>
    >>> I'm starting to notice that this pattern (testing ISREG and
    >>> MNT_NOEXEC) is getting repeated a few times in the kernel, and at
    >>> least the no-new-privs patch (not yet in -mm but hopefully soon given
    >>> the seccomp_filter work) updates this pattern everywhere. Perhaps this
    >>> should be extracted into a helper first, and then this patch can call
    >>> that helper here? (And then nnp can just update the single helper.)
    >>>
    >>
    >> I can do that if Andrew agree.
    >
    > I'm a bit lost.  nnp updates the MNT_NOSUID checks, not the MNT_NOEXEC
    > checks.  (And the effects of the two flags is different in selinux for
    > historical reasons.)  I'm sure I'm missing something.

    Oops, you're right. Regardless, we might want helpers anyway. Better
    to have single places to do these tests.

    -Kees

    --
    Kees Cook
    ChromeOS Security
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