linux-kernel - Re: [PATCH v2 03/14] nvmet: Implement CCR nvme command

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Message-ID: <20260204175250.GL3729-mkhalfella@purestorage.com>
Date: Wed, 4 Feb 2026 09:52:50 -0800
From: Mohamed Khalfella <mkhalfella@...estorage.com>
To: Hannes Reinecke <hare@...e.de>
Cc: Justin Tee <justin.tee@...adcom.com>,
	Naresh Gottumukkala <nareshgottumukkala83@...il.com>,
	Paul Ely <paul.ely@...adcom.com>,
	Chaitanya Kulkarni <kch@...dia.com>, Christoph Hellwig <hch@....de>,
	Jens Axboe <axboe@...nel.dk>, Keith Busch <kbusch@...nel.org>,
	Sagi Grimberg <sagi@...mberg.me>,
	Aaron Dailey <adailey@...estorage.com>,
	Randy Jennings <randyj@...estorage.com>,
	Dhaval Giani <dgiani@...estorage.com>,
	linux-nvme@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 03/14] nvmet: Implement CCR nvme command

On Wed 2026-02-04 01:55:18 +0100, Hannes Reinecke wrote:
> On 2/4/26 01:44, Mohamed Khalfella wrote:
> > On Wed 2026-02-04 01:38:44 +0100, Hannes Reinecke wrote:
> >> On 2/3/26 19:40, Mohamed Khalfella wrote:
> >>> On Tue 2026-02-03 04:19:50 +0100, Hannes Reinecke wrote:
> >>>> On 1/30/26 23:34, Mohamed Khalfella wrote:
> >>>>> @@ -1501,6 +1516,38 @@ struct nvmet_ctrl *nvmet_ctrl_find_get(const char *subsysnqn,
> >>>>>     	return ctrl;
> >>>>>     }
> >>>>>     
> >>>>> +struct nvmet_ctrl *nvmet_ctrl_find_get_ccr(struct nvmet_subsys *subsys,
> >>>>> +					   const char *hostnqn, u8 ciu,
> >>>>> +					   u16 cntlid, u64 cirn)
> >>>>> +{
> >>>>> +	struct nvmet_ctrl *ctrl;
> >>>>> +	bool found = false;
> >>>>> +
> >>>>> +	mutex_lock(&subsys->lock);
> >>>>> +	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry) {
> >>>>> +		if (ctrl->cntlid != cntlid)
> >>>>> +			continue;
> >>>>> +		if (strncmp(ctrl->hostnqn, hostnqn, NVMF_NQN_SIZE))
> >>>>> +			continue;
> >>>>> +
> >>>> Why do we compare the hostnqn here, too? To my understanding the host
> >>>> NQN is tied to the controller, so the controller ID should be sufficient
> >>>> here.
> >>>
> >>> We got cntlid from CCR nvme command and we do not trust the value sent by
> >>> the host. We check hostnqn to confirm that host is actually connected to
> >>> the impacted controller. A host should not be allowed to reset a
> >>> controller connected to another host.
> >>>
> >> Errm. So we're starting to not trust values in NVMe commands?
> >> That is a very slippery road.
> >> Ultimately it would require us to validate the cntlid on each
> >> admin command. Which we don't.
> >> And really there is no difference between CCR and any other
> >> admin command; you get even worse effects if you would assume
> >> a misdirected 'FORMAT' command.
> >>
> >> Please don't. Security is _not_ a concern here.
> > 
> > I do not think the check hurts. If you say it is wrong I will delete it.
> > 
> It's not 'wrong', It's inconsistent. The argument that the contents of
> an admin command may be wrong applies to _every_ admin command.
> Yet we never check on any of those commands.
> So I fail to see why this command requires special treatment.

Okay, I will delete this check.

> 
> Cheers,
> 
> Hannes
> -- 
> Dr. Hannes Reinecke                  Kernel Storage Architect
> hare@...e.de                                +49 911 74053 688
> SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
> HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich