linux-kernel - Re: [PATCH v2 3/4] selinux: use vma_is_initial_stack() and vma_is_initial

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Message-ID: <CAJ2a_DfGvPeDuN38UBXD4f2928n9GZpHFgdiPo9MoSAY7YXeOg@mail.gmail.com>
Date:   Wed, 19 Jul 2023 11:02:22 +0200
From:   Christian Göttsche <cgzones@...glemail.com>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-perf-users@...r.kernel.org,
        selinux@...r.kernel.org, Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>
Subject: Re: [PATCH v2 3/4] selinux: use vma_is_initial_stack() and vma_is_initial_heap()

On Wed, 19 Jul 2023 at 09:40, Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
>
> Use the helpers to simplify code.
>
> Cc: Paul Moore <paul@...l-moore.com>
> Cc: Stephen Smalley <stephen.smalley.work@...il.com>
> Cc: Eric Paris <eparis@...isplace.org>
> Acked-by: Paul Moore <paul@...l-moore.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> ---
>  security/selinux/hooks.c | 7 ++-----
>  1 file changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
> index d06e350fedee..ee8575540a8e 100644
> --- a/security/selinux/hooks.c
> +++ b/security/selinux/hooks.c
> @@ -3762,13 +3762,10 @@ static int selinux_file_mprotect(struct vm_area_struct *vma,
>         if (default_noexec &&
>             (prot & PROT_EXEC) && !(vma->vm_flags & VM_EXEC)) {
>                 int rc = 0;
> -               if (vma->vm_start >= vma->vm_mm->start_brk &&
> -                   vma->vm_end <= vma->vm_mm->brk) {
> +               if (vma_is_initial_heap(vma)) {

This seems to change the condition from

    vma->vm_start >= vma->vm_mm->start_brk && vma->vm_end <= vma->vm_mm->brk

to

    vma->vm_start <= vma->vm_mm->brk && vma->vm_end >= vma->vm_mm->start_brk

(or AND arguments swapped)

    vma->vm_end >= vma->vm_mm->start_brk && vma->vm_start <= vma->vm_mm->brk

Is this intended?

>                         rc = avc_has_perm(sid, sid, SECCLASS_PROCESS,
>                                           PROCESS__EXECHEAP, NULL);
> -               } else if (!vma->vm_file &&
> -                          ((vma->vm_start <= vma->vm_mm->start_stack &&
> -                            vma->vm_end >= vma->vm_mm->start_stack) ||
> +               } else if (!vma->vm_file && (vma_is_initial_stack(vma) ||
>                             vma_is_stack_for_current(vma))) {
>                         rc = avc_has_perm(sid, sid, SECCLASS_PROCESS,
>                                           PROCESS__EXECSTACK, NULL);
> --
> 2.27.0
>