netdev - Re: [PATCH v4 6/7] nvme-tcp: Allow userspace to trigger a KeyUpdate with debugfs

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Message-ID: <8d6d76b4-6361-4392-9351-bd9d59c96ba0@suse.de>
Date: Mon, 20 Oct 2025 08:33:01 +0200
From: Hannes Reinecke <hare@...e.de>
To: alistair23@...il.com, chuck.lever@...cle.com, hare@...nel.org,
 kernel-tls-handshake@...ts.linux.dev, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-nvme@...ts.infradead.org, linux-nfs@...r.kernel.org
Cc: kbusch@...nel.org, axboe@...nel.dk, hch@....de, sagi@...mberg.me,
 kch@...dia.com, Alistair Francis <alistair.francis@....com>
Subject: Re: [PATCH v4 6/7] nvme-tcp: Allow userspace to trigger a KeyUpdate
 with debugfs

On 10/17/25 06:23, alistair23@...il.com wrote:
> From: Alistair Francis <alistair.francis@....com>
> 
> Allow userspace to trigger a KeyUpdate via debugfs. This patch exposes a
> key_update file that can be written to with the queue number to trigger
> a KeyUpdate on that queue.
> 
> Signed-off-by: Alistair Francis <alistair.francis@....com>
> ---
> v4:
>   - No change
> v3:
>   - New patch
> 
>   drivers/nvme/host/tcp.c | 72 +++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 72 insertions(+)
> 
> diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
> index 791e0cc91ad8..f5c7b646d002 100644
> --- a/drivers/nvme/host/tcp.c
> +++ b/drivers/nvme/host/tcp.c
> @@ -11,6 +11,7 @@
>   #include <linux/crc32.h>
>   #include <linux/nvme-tcp.h>
>   #include <linux/nvme-keyring.h>
> +#include <linux/debugfs.h>
>   #include <net/sock.h>
>   #include <net/tcp.h>
>   #include <net/tls.h>
> @@ -1429,6 +1430,75 @@ static void update_tls_keys(struct nvme_tcp_queue *queue)
>   	}
>   }
>   
> +#ifdef CONFIG_NVME_TCP_TLS
> +#define NVME_DEBUGFS_RW_ATTR(field) \
> +	static int field##_open(struct inode *inode, struct file *file) \
> +	{ return single_open(file, field##_show, inode->i_private); } \
> +	\
> +	static const struct file_operations field##_fops = { \
> +		.open = field##_open, \
> +		.read = seq_read, \
> +		.write = field##_write, \
> +		.release = single_release, \
> +	}
> +
> +static int nvme_ctrl_key_update_show(struct seq_file *m, void *p)
> +{
> +	seq_printf(m, "0\n");
> +
> +	return 0;
> +}
> +
> +static ssize_t nvme_ctrl_key_update_write(struct file *file, const char __user *buf,
> +					  size_t count, loff_t *ppos)
> +{
> +	struct seq_file *m = file->private_data;
> +	struct nvme_ctrl *nctrl = m->private;
> +	struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
> +	char kbuf[16] = {0};
> +	int queue_nr, rc;
> +	struct nvme_tcp_queue *queue;
> +
> +	if (count > sizeof(kbuf) - 1)
> +		return -EINVAL;
> +	if (copy_from_user(kbuf, buf, count))
> +		return -EFAULT;
> +	kbuf[count] = 0;
> +
> +	rc = kstrtouint(kbuf, 10, &queue_nr);
> +	if (rc)
> +		return rc;
> +
> +	if (queue_nr >= nctrl->queue_count)
> +		return -EINVAL;
> +
> +	queue = &ctrl->queues[queue_nr];
> +
> +	update_tls_keys(queue);

Are you sure this is correct?

'update_tls_keys' is issuing a handshake request
with 'HANDSHAKE_KEY_UPDATE_TYPE_RECEIVED'.

And the patch introducing it states:
At this time we don't support initiating a KeyUpdate.

So please move this to the patchset implementing support
for initiating KeyUpdates.

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