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

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Message-ID: <20260204004417.GK3729-mkhalfella@purestorage.com>
Date: Tue, 3 Feb 2026 16:44:17 -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 01:38:44 +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.

> 
> 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