[PATCH] nvme: expose TLS mode

[PATCH] nvme: expose TLS mode

[Daniel Wagner]

It is not possible to determine the active TLS mode from the
presence or absence of sysfs attributes like tls_key,
tls_configured_key, or dhchap_secret.

With the introduction of the concat mode and optional DH-CHAP
authentication, different configurations can result in identical
sysfs state. This makes user space detection unreliable.

Expose the TLS mode explicitly to allow user space to
unambiguously identify the active configuration and avoid
fragile heuristics in nvme-cli.

Signed-off-by: Daniel Wagner <wagi@kernel.org>
---
I am extending the test suite for nvme-cli to cover the use case of
nvme connect --tls/--concat.

Currently, nvme-cli uses heuristics to determine whether --tls was used
to initiate the connection. With the introduction of --concat, these
heuristics are no longer reliable.

By exposing the TLS mode explicitly, nvme config can now generate a
configuration based on the currently active connection.

$ nvme config --scan --dump --output-format json /dev/nvme1
[
  {
    "hostnqn":"nqn.2014-08.org.nvmexpress:uuid:befdec4c-2234-11b2-a85c-ca77c773af36",
    "hostid":"befdec4c-2234-11b2-a85c-ca77c773af36",
    "dhchap_key":"DHHC-1:01:1+pb0VSbn3cBrOhwP5SHa6gwlbPikdZ0mmBKKXC74Sm0s0pb:",
    "subsystems":[
      {
        "nqn":"nqn.io-1",
        "ports":[
          {
            "transport":"tcp",
            "traddr":"192.168.30.30",
            "trsvcid":"4420",
            "dhchap_key":"DHHC-1:01:1+pb0VSbn3cBrOhwP5SHa6gwlbPikdZ0mmBKKXC74Sm0s0pb:",
            "dhchap_ctrl_key":"DHHC-1:01:uTcIEwLZsEoVJucx7sKVvzfwOTAfJ9ZGcvYWswHwF41mMSW1:",
            "tls":true,
            "keyring":".nvme"
          }
        ]
      }
    ]
  }
]
---
 drivers/nvme/host/sysfs.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 16c6fea4b2db..c4b5241371d6 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -810,6 +810,23 @@ const struct attribute_group nvme_dev_attrs_group = {
 EXPORT_SYMBOL_GPL(nvme_dev_attrs_group);
 
 #ifdef CONFIG_NVME_TCP_TLS
+static ssize_t tls_mode_show(struct device *dev,
+			     struct device_attribute *attr, char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+	const char *mode;
+
+	if (ctrl->opts->tls)
+		mode = "tls";
+	else if (ctrl->opts->concat)
+		mode = "concat";
+	else
+		mode = "none";
+
+	return sysfs_emit(buf, "%s\n", mode);
+}
+static DEVICE_ATTR_RO(tls_mode);
+
 static ssize_t tls_key_show(struct device *dev,
 			    struct device_attribute *attr, char *buf)
 {
@@ -845,6 +862,7 @@ static struct attribute *nvme_tls_attrs[] = {
 	&dev_attr_tls_key.attr,
 	&dev_attr_tls_configured_key.attr,
 	&dev_attr_tls_keyring.attr,
+	&dev_attr_tls_mode.attr,
 	NULL,
 };
 

---
base-commit: 7aaa8047eafd0bd628065b15757d9b48c5f9c07d
change-id: 20260401-expose-tls-mode-10fdb5d459d4

Best regards,
--  
Daniel Wagner <wagi@kernel.org>

Re: [PATCH] nvme: expose TLS mode

[Daniel Wagner]

On Wed, Apr 01, 2026 at 10:52:00AM +0200, Daniel Wagner wrote:
> $ nvme config --scan --dump --output-format json /dev/nvme1

and posted the wrong example output...

nvme connect --transport tcp --traddr 192.168.30.30 --trsvcid 4420 \
        --hostnqn nqn.2014-08.org.nvmexpress:uuid:befdec4c-2234-11b2-a85c-ca77c773af36 \
        --nqn nqn.io-1 --concat \
        --dhchap-secret=DHHC-1:01:1+pb0VSbn3cBrOhwP5SHa6gwlbPikdZ0mmBKKXC74Sm0s0pb: \
        --dump-config --output-format json
[
  {
    "hostnqn":"nqn.2014-08.org.nvmexpress:uuid:befdec4c-2234-11b2-a85c-ca77c773af36",
    "hostid":"befdec4c-2234-11b2-a85c-ca77c773af36",
    "dhchap_key":"DHHC-1:01:1+pb0VSbn3cBrOhwP5SHa6gwlbPikdZ0mmBKKXC74Sm0s0pb:",
    "subsystems":[
      {
        "nqn":"nqn.io-1",
        "ports":[
          {
            "transport":"tcp",
            "traddr":"192.168.30.30",
            "trsvcid":"4420",
            "dhchap_key":"DHHC-1:01:1+pb0VSbn3cBrOhwP5SHa6gwlbPikdZ0mmBKKXC74Sm0s0pb:",
            "concat":true
          }
        ]
      }
    ]
  }
]

nvme config --scan --dump --output-format json /dev/nvme1
[
  {
    "hostnqn":"nqn.2014-08.org.nvmexpress:uuid:befdec4c-2234-11b2-a85c-ca77c773af36",
    "hostid":"befdec4c-2234-11b2-a85c-ca77c773af36",
    "dhchap_key":"DHHC-1:01:1+pb0VSbn3cBrOhwP5SHa6gwlbPikdZ0mmBKKXC74Sm0s0pb:",
    "subsystems":[
      {
    "subsystems":[
      {
        "nqn":"nqn.io-1",
        "ports":[
          {
            "transport":"tcp",
            "traddr":"192.168.30.30",
            "trsvcid":"4420",
            "dhchap_key":"DHHC-1:01:1+pb0VSbn3cBrOhwP5SHa6gwlbPikdZ0mmBKKXC74Sm0s0pb:",
            "concat":true
          }
        ]
      }
    ]
  }
]

Re: [PATCH] nvme: expose TLS mode

[Christoph Hellwig]

Looks fine to me with the example fixed.

Re: [PATCH] nvme: expose TLS mode

[Daniel Wagner]

On Wed, Apr 01, 2026 at 04:09:34PM +0200, Christoph Hellwig wrote:
> Looks fine to me with the example fixed.

BTW, do you think an empty string is better instead of "none" when TLS
is off? 

Re: [PATCH] nvme: expose TLS mode

[Christoph Hellwig]

On Thu, Apr 02, 2026 at 08:42:57AM +0200, Daniel Wagner wrote:
> On Wed, Apr 01, 2026 at 04:09:34PM +0200, Christoph Hellwig wrote:
> > Looks fine to me with the example fixed.
> 
> BTW, do you think an empty string is better instead of "none" when TLS
> is off? 

Empty strings are confusing, so either none or off would be much
preferred. Out of the two none would be my slight preference.