linux-kernel - Re: [RFC PATCH 13/16] arm64: mm: Reset pkey in __tlb_remove

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

Message-ID: <20241210122706.GO8562@noisy.programming.kicks-ass.net>
Date: Tue, 10 Dec 2024 13:27:06 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: Kevin Brodsky <kevin.brodsky@....com>
Cc: linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
	aruna.ramakrishna@...cle.com, broonie@...nel.org,
	catalin.marinas@....com, dave.hansen@...ux.intel.com,
	jannh@...gle.com, jeffxu@...omium.org, joey.gouly@....com,
	kees@...nel.org, maz@...nel.org, pierre.langlois@....com,
	qperret@...gle.com, ryan.roberts@....com, will@...nel.org,
	linux-arm-kernel@...ts.infradead.org, x86@...nel.org
Subject: Re: [RFC PATCH 13/16] arm64: mm: Reset pkey in __tlb_remove_table()

On Tue, Dec 10, 2024 at 10:28:44AM +0100, Kevin Brodsky wrote:
> On 09/12/2024 11:29, Peter Zijlstra wrote:
> > On Fri, Dec 06, 2024 at 10:11:07AM +0000, Kevin Brodsky wrote:
> >> [...]
> >>
> >> diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
> >> index a947c6e784ed..d1611ffa6d91 100644
> >> --- a/arch/arm64/include/asm/tlb.h
> >> +++ b/arch/arm64/include/asm/tlb.h
> >> @@ -10,10 +10,14 @@
> >>  
> >>  #include <linux/pagemap.h>
> >>  #include <linux/swap.h>
> >> +#include <linux/kpkeys.h>
> >>  
> >>  static inline void __tlb_remove_table(void *_table)
> >>  {
> >> -	free_page_and_swap_cache((struct page *)_table);
> >> +	struct page *page = (struct page *)_table;
> >> +
> >> +	kpkeys_unprotect_pgtable_memory((unsigned long)page_address(page), 1);
> >> +	free_page_and_swap_cache(page);
> >>  }
> > Same as for the others, perhaps stick this in generic code instead of in
> > the arch code?
> 
> This should be doable, with some refactoring. __tlb_remove_table() is
> currently called from two functions in mm/mmu_gather.c, I suppose I
> could create a wrapper there that calls
> kpkeys_unprotect_pgtable_memory() and then __tlb_remove_table(). Like in
> the p4d case I do however wonder how robust this is, as
> __tlb_remove_table() could end up being called from other places.

I don't foresee other __tlb_remove_table() users, this is all rather
speicific code. But if there ever were to be new users, it is something
they would have to take into consideration.