linux-kernel - Re: [PATCH] ELF: warn if process starts with executable stack

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Date:   Mon, 18 Nov 2019 17:13:41 +0000
From:   Ben Dooks <ben.dooks@...ethink.co.uk>
To:     Alexey Dobriyan <adobriyan@...il.com>, akpm@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        security@...nel.org
Subject: Re: [PATCH] ELF: warn if process starts with executable stack

On 18/11/2019 14:51, Alexey Dobriyan wrote:
> PT_GNU_STACK is fail open design, at least warn people that something
> isn't right.
> 
> Signed-off-by: Alexey Dobriyan <adobriyan@...il.com>
> ---
> 
>   fs/exec.c |    7 +++++++
>   1 file changed, 7 insertions(+)
> 
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -762,6 +762,13 @@ int setup_arg_pages(struct linux_binprm *bprm,
>   		goto out_unlock;
>   	BUG_ON(prev != vma);
>   

it might be worth to use:
  if (IS_ENABLED(CONFIG_MMU) && vm_flags & VM_EXEC) {

instead of the #ifdef


> +#ifdef CONFIG_MMU
> +	if (vm_flags & VM_EXEC) {
> +		pr_warn_once("process '%s'/%u started with executable stack\n",
> +			     current->comm, current->pid);
> +	}
> +#endif
> +
>   	/* Move stack pages down in memory. */
>   	if (stack_shift) {
>   		ret = shift_arg_pages(vma, stack_shift);
> 


-- 
Ben Dooks				http://www.codethink.co.uk/
Senior Engineer				Codethink - Providing Genius

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