linux-kernel - Re: [PATCH V8 04/44] x86/pkeys: Add additional PKEY helper macros

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]

Date:   Wed, 2 Feb 2022 12:21:59 -0800
From:   Ira Weiny <ira.weiny@...el.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V8 04/44] x86/pkeys: Add additional PKEY helper macros

On Fri, Jan 28, 2022 at 02:47:30PM -0800, Dave Hansen wrote:
> On 1/27/22 09:54, ira.weiny@...el.com wrote:
> > +#define PKR_AD_KEY(pkey)	(PKR_AD_BIT << PKR_PKEY_SHIFT(pkey))
> > +#define PKR_WD_KEY(pkey)	(PKR_WD_BIT << PKR_PKEY_SHIFT(pkey))
> 
> I don't _hate_ this, but naming here is wonky for me.  PKR_WD_KEY reads
> to me as "pkey register write-disable key", as in, please write-disable
> this key, or maybe "make a write-disable key".

Ok...  that is reasonable...

> 
> It's generating a mask, so I'd probably name it:
> 
> #define PKR_WD_MASK(pkey)	(PKR_WD_BIT << PKR_PKEY_SHIFT(pkey))
> 
> Which says, "generate a write-disabled mask for this pkey".

I think the confusion comes from me having used these as mask values rather
than what PKR_AD_KEY() was intended to be used for.

In the previous patch PKR_AD_KEY() is used to set up the default user pkey
value...

u32 init_pkru_value = PKR_AD_KEY( 1) | PKR_AD_KEY( 2) | PKR_AD_KEY( 3) |
		      PKR_AD_KEY( 4) | PKR_AD_KEY( 5) | PKR_AD_KEY( 6) |
		      PKR_AD_KEY( 7) | PKR_AD_KEY( 8) | PKR_AD_KEY( 9) |
		      PKR_AD_KEY(10) | PKR_AD_KEY(11) | PKR_AD_KEY(12) |
		      PKR_AD_KEY(13) | PKR_AD_KEY(14) | PKR_AD_KEY(15);

I'll have to think about it but I don't think I like the following...

u32 init_pkru_value = PKR_AD_MASK( 1) | PKR_AD_MASK( 2) | PKR_AD_MASK( 3) |
		      PKR_AD_MASK( 4) | PKR_AD_MASK( 5) | PKR_AD_MASK( 6) |
		      PKR_AD_MASK( 7) | PKR_AD_MASK( 8) | PKR_AD_MASK( 9) |
		      PKR_AD_MASK(10) | PKR_AD_MASK(11) | PKR_AD_MASK(12) |
		      PKR_AD_MASK(13) | PKR_AD_MASK(14) | PKR_AD_MASK(15);

It seems odd to me.  Does it seem odd to you?

Looking at the final code I think I'm going to just drop the usages in this
patch and add PKR_WD_KEY() where it is used first.

Also, how about PKR_KEY_INIT_{AD|WD|RW}() as a name?

Ira