linux-kernel - Re: [PATCH v7 2/7] kexec: define functions to map and unmap segments

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Message-ID: <Z7QLYd5ZFmQuV8Gx@MiWiFi-R3L-srv>
Date: Tue, 18 Feb 2025 12:24:01 +0800
From: Baoquan He <bhe@...hat.com>
To: Mimi Zohar <zohar@...ux.ibm.com>
Cc: steven chen <chenste@...ux.microsoft.com>, stefanb@...ux.ibm.com,
	roberto.sassu@...weicloud.com, roberto.sassu@...wei.com,
	eric.snowberg@...cle.com, ebiederm@...ssion.com,
	paul@...l-moore.com, code@...icks.com, bauermann@...abnow.com,
	linux-integrity@...r.kernel.org, kexec@...ts.infradead.org,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org,
	madvenka@...ux.microsoft.com, nramas@...ux.microsoft.com,
	James.Bottomley@...senpartnership.com
Subject: Re: [PATCH v7 2/7] kexec: define functions to map and unmap segments

On 02/12/25 at 08:03am, Mimi Zohar wrote:
> On Mon, 2025-02-10 at 09:06 -0800, steven chen wrote:
> > On 2/7/2025 11:15 AM, Mimi Zohar wrote:
> > > Hi Steven,
> > > 
> > > On Mon, 2025-02-03 at 15:20 -0800, steven chen wrote:
> > > > Currently, the mechanism to map and unmap segments to the kimage
> > > > structure is not available to the subsystems outside of kexec.  This
> > > > functionality is needed when IMA is allocating the memory segments
> > > > during kexec 'load' operation.  Implement functions to map and unmap
> > > > segments to kimage.
> > > > 
> > > > Implement kimage_map_segment() to enable mapping of IMA buffer source
> > > > pages to the kimage structure post kexec 'load'.  This function,
> > > > accepting a kimage pointer, an address, and a size, will gather the
> > > > source pages within the specified address range, create an array of page
> > > > pointers, and map these to a contiguous virtual address range.  The
> > > > function returns the start of this range if successful, or NULL if
> > > > unsuccessful.
> > > > 
> > > > Implement kimage_unmap_segment() for unmapping segments
> > > > using vunmap().
> > > > 
> > > > From: Tushar Sugandhi <tusharsu@...ux.microsoft.com>
> > > > Author: Tushar Sugandhi <tusharsu@...ux.microsoft.com>
> > > > Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
> > > > Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
> > > I don't recall previously adding my "Reviewed-by" tag.
> > > 
> > > Eric, I'd appreciate your reviewing this and the subsequent patch "[PATCH v7 3/7]
> > > ima: kexec: skip IMA segment validation after kexec soft reboot" in particular.
> > Hi Eric, Could you help to review this patch as Mimi mentioned? Thanks!
> > > 
> > > > Signed-off-by: Tushar Sugandhi <tusharsu@...ux.microsoft.com>
> 
> Steven, since these patches impact kdump, before re-posting the patch set, please
> include the following tags before your Signed-off-by tag on the kexec patches.

Thanks, Mimi.

Yes, Steven, please add me in CC when reposting. Thanks in advance.

I will check this version to see if there's impact on kexec/kdump
from my side.

And by the way, kdump should not need IMA, it's better be disabled by
default. I will have a look and try disabling it in kdump kernel, while
really appreciate it if any IMA expert can do it.

Thanks
Baoquan