linux-kernel - Re: [PATCH] uprobes: Refuse to insert a probe into MAP

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20140428193029.GA9773@redhat.com>
Date:	Mon, 28 Apr 2014 21:30:29 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, Hugh Dickins <hughd@...gle.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	David Long <dave.long@...aro.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] uprobes: Refuse to insert a probe into MAP_SHARED vma

And of course, I forgot to add Hugh ;) Fix that.

On 04/28, Oleg Nesterov wrote:
>
> valid_vma() rejects the VM_SHARED vmas, but this still allows to insert
> a probe into the MAP_SHARED but not VM_MAYWRITE vma.
> 
> Currently this is fine, such a mapping doesn't really differ from the
> private read-only mmap except mprotect(PROT_WRITE) won't work. However,
> get_user_pages(FOLL_WRITE | FOLL_FORCE) doesn't allow to COW in this
> case, and it would be safer to follow the same conventions as mm even
> if currently this happens to work.
> 
> After the recent cda540ace6a1 "mm: get_user_pages(write,force) refuse
> to COW in shared areas" only uprobes can insert an anon page into the
> shared file-backed area, lets stop this and change valid_vma() to check
> VM_MAYSHARE instead.
> 
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  kernel/events/uprobes.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index d1edc5e..7716c40 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -127,7 +127,7 @@ struct xol_area {
>   */
>  static bool valid_vma(struct vm_area_struct *vma, bool is_register)
>  {
> -	vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_SHARED;
> +	vm_flags_t flags = VM_HUGETLB | VM_MAYEXEC | VM_MAYSHARE;
>  
>  	if (is_register)
>  		flags |= VM_WRITE;
> -- 
> 1.5.5.1
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/