[PATCH v3 1/2] nvmet-tcp: validate the TLS handshake timeout

[PATCH v3 1/2] nvmet-tcp: validate the TLS handshake timeout

[Yingjie Wang]

tls_handshake_timeout is writable but stored as a signed int. Multiplying
the value by MSEC_PER_SEC and HZ therefore uses signed arithmetic.

With HZ=1000, setting it to 2147484 overflows both multiplications. If
the handshake request is accepted and remains pending, the timer wheel
treats the jiffies delay as already expired and queues the timeout work
on its next advance, while the handshake agent was given about 24.9
days. Negative values such as -1 cause the same immediate kernel-side
timeout.

Store the parameter as an unsigned int and reject values that cannot be
represented both by tls_handshake_args::ta_timeout_ms and by a safe
jiffies delay. Take one snapshot so a concurrent parameter update cannot
give the handshake agent and delayed work different timeouts. Document
the accepted range for built-in use.

Negative and oversized values now fail with -EINVAL. Keep zero valid,
preserving the existing immediate-timeout behavior.

Fixes: 675b453e0241 ("nvmet-tcp: enable TLS handshake upcall")
Cc: stable@vger.kernel.org
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Yingjie Wang <1075151112@qq.com>
---
 .../admin-guide/kernel-parameters.txt         |  5 ++++
 drivers/nvme/target/tcp.c                     | 26 ++++++++++++++++---
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 68647ff4bdd24..5bd8a24be6b61 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4801,6 +4801,11 @@ Kernel parameters
 			Example:
 			nvme.quirks=7710:2267:bogus_nid,^identify_cns-9900:7711:broken_msi
 
+	nvmet_tcp.tls_handshake_timeout=
+			[NVME] NVMe/TCP target TLS handshake timeout in seconds.
+			Valid values range from 0 to the smaller of
+			UINT_MAX / 1000 and MAX_JIFFY_OFFSET / HZ. Default: 10
+
 	ohci1394_dma=early	[HW,EARLY] enable debugging via the ohci1394 driver.
 			See Documentation/core-api/debugging-via-ohci1394.rst for more
 			info.
diff --git a/drivers/nvme/target/tcp.c b/drivers/nvme/target/tcp.c
index e598101752620..7937377436d3b 100644
--- a/drivers/nvme/target/tcp.c
+++ b/drivers/nvme/target/tcp.c
@@ -6,6 +6,7 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/jiffies.h>
 #include <linux/slab.h>
 #include <linux/crc32c.h>
 #include <linux/err.h>
@@ -76,8 +77,24 @@ MODULE_PARM_DESC(idle_poll_period_usecs,
 /*
  * TLS handshake timeout
  */
-static int tls_handshake_timeout = 10;
-module_param(tls_handshake_timeout, int, 0644);
+static unsigned int tls_handshake_timeout = 10;
+
+static int tls_handshake_timeout_set(const char *val,
+				     const struct kernel_param *kp)
+{
+	return param_set_uint_minmax(val, kp, 0,
+		min_t(unsigned long, UINT_MAX / MSEC_PER_SEC,
+		      MAX_JIFFY_OFFSET / HZ));
+}
+
+static const struct kernel_param_ops tls_handshake_timeout_ops = {
+	.set = tls_handshake_timeout_set,
+	.get = param_get_uint,
+};
+
+module_param_cb(tls_handshake_timeout, &tls_handshake_timeout_ops,
+		&tls_handshake_timeout, 0644);
+__MODULE_PARM_TYPE(tls_handshake_timeout, "uint");
 MODULE_PARM_DESC(tls_handshake_timeout,
 		 "nvme TLS handshake timeout in seconds (default 10)");
 #endif
@@ -1904,6 +1921,7 @@ static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue)
 {
 	int ret = -EOPNOTSUPP;
 	struct tls_handshake_args args;
+	unsigned int timeout = READ_ONCE(tls_handshake_timeout);
 
 	if (queue->state != NVMET_TCP_Q_TLS_HANDSHAKE) {
 		pr_warn("cannot start TLS in state %d\n", queue->state);
@@ -1917,7 +1935,7 @@ static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue)
 	args.ta_done = nvmet_tcp_tls_handshake_done;
 	args.ta_data = queue;
 	args.ta_keyring = key_serial(queue->port->nport->keyring);
-	args.ta_timeout_ms = tls_handshake_timeout * 1000;
+	args.ta_timeout_ms = timeout * MSEC_PER_SEC;
 
 	ret = tls_server_hello_psk(&args, GFP_KERNEL);
 	if (ret) {
@@ -1925,7 +1943,7 @@ static int nvmet_tcp_tls_handshake(struct nvmet_tcp_queue *queue)
 		pr_err("failed to start TLS, err=%d\n", ret);
 	} else {
 		queue_delayed_work(nvmet_wq, &queue->tls_handshake_tmo_work,
-				   tls_handshake_timeout * HZ);
+				   (unsigned long)timeout * HZ);
 	}
 	return ret;
 }
-- 
2.43.0

Re: [PATCH v3 1/2] nvmet-tcp: validate the TLS handshake timeout

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

[PATCH v3 2/2] nvme-tcp: validate the TLS handshake timeout

[Yingjie Wang]

tls_handshake_timeout is writable but stored as a signed int. Multiplying
the value by MSEC_PER_SEC and HZ therefore uses signed arithmetic.

With HZ=1000, setting it to 2147484 overflows both multiplications. If
the handshake request is accepted and its completion remains pending,
schedule_timeout() reports a wrong timeout value with a stack dump and
returns zero. The handshake then fails immediately with -ETIMEDOUT,
while the handshake agent was given about 24.9 days. Negative values
such as -1 have the same kernel-side effect.

Store the parameter as an unsigned int and reject values that cannot be
represented both by tls_handshake_args::ta_timeout_ms and by a safe
jiffies delay. Take one snapshot so a concurrent parameter update cannot
give the handshake agent and completion wait different timeouts.
Document the accepted range for built-in use.

wait_for_completion_interruptible_timeout() returns the remaining
jiffies as a long after a successful completion. Keep that result in a
long because an accepted timeout can exceed INT_MAX jiffies on 64-bit
systems.

Negative and oversized values now fail with -EINVAL. Keep zero valid,
preserving the existing immediate-timeout behavior.

Fixes: be8e82caa685 ("nvme-tcp: enable TLS handshake upcall")
Cc: stable@vger.kernel.org
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Signed-off-by: Yingjie Wang <1075151112@qq.com>
---
 .../admin-guide/kernel-parameters.txt         |  5 +++
 drivers/nvme/host/tcp.c                       | 34 ++++++++++++++-----
 2 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 5bd8a24be6b61..187917a4f196d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4801,6 +4801,11 @@ Kernel parameters
 			Example:
 			nvme.quirks=7710:2267:bogus_nid,^identify_cns-9900:7711:broken_msi
 
+	nvme_tcp.tls_handshake_timeout=
+			[NVME] NVMe/TCP host TLS handshake timeout in seconds.
+			Valid values range from 0 to the smaller of
+			UINT_MAX / 1000 and MAX_JIFFY_OFFSET / HZ. Default: 10
+
 	nvmet_tcp.tls_handshake_timeout=
 			[NVME] NVMe/TCP target TLS handshake timeout in seconds.
 			Valid values range from 0 to the smaller of
diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index dbefe36b0575e..1b9c090bfda93 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -6,6 +6,7 @@
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/jiffies.h>
 #include <linux/slab.h>
 #include <linux/async.h>
 #include <linux/err.h>
@@ -48,9 +49,24 @@ MODULE_PARM_DESC(wq_unbound, "Use unbound workqueue for nvme-tcp IO context (def
 /*
  * TLS handshake timeout
  */
-static int tls_handshake_timeout = 10;
+static unsigned int tls_handshake_timeout = 10;
 #ifdef CONFIG_NVME_TCP_TLS
-module_param(tls_handshake_timeout, int, 0644);
+static int tls_handshake_timeout_set(const char *val,
+				     const struct kernel_param *kp)
+{
+	return param_set_uint_minmax(val, kp, 0,
+		min_t(unsigned long, UINT_MAX / MSEC_PER_SEC,
+		      MAX_JIFFY_OFFSET / HZ));
+}
+
+static const struct kernel_param_ops tls_handshake_timeout_ops = {
+	.set = tls_handshake_timeout_set,
+	.get = param_get_uint,
+};
+
+module_param_cb(tls_handshake_timeout, &tls_handshake_timeout_ops,
+		&tls_handshake_timeout, 0644);
+__MODULE_PARM_TYPE(tls_handshake_timeout, "uint");
 MODULE_PARM_DESC(tls_handshake_timeout,
 		 "nvme TLS handshake timeout in seconds (default 10)");
 #endif
@@ -1930,8 +1946,10 @@ static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
 {
 	int qid = nvme_tcp_queue_id(queue);
 	int ret;
+	long wait_ret;
 	struct tls_handshake_args args;
-	unsigned long tmo = tls_handshake_timeout * HZ;
+	unsigned int timeout = READ_ONCE(tls_handshake_timeout);
+	unsigned long tmo = (unsigned long)timeout * HZ;
 	key_serial_t keyring = nvme_keyring_id();
 
 	dev_dbg(nctrl->device, "queue %d: start TLS with key %x\n",
@@ -1945,7 +1963,7 @@ static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
 	if (nctrl->opts->keyring)
 		keyring = key_serial(nctrl->opts->keyring);
 	args.ta_keyring = keyring;
-	args.ta_timeout_ms = tls_handshake_timeout * 1000;
+	args.ta_timeout_ms = timeout * MSEC_PER_SEC;
 	queue->tls_err = -EOPNOTSUPP;
 	init_completion(&queue->tls_complete);
 	ret = tls_client_hello_psk(&args, GFP_KERNEL);
@@ -1954,10 +1972,10 @@ static int nvme_tcp_start_tls(struct nvme_ctrl *nctrl,
 			qid, ret);
 		return ret;
 	}
-	ret = wait_for_completion_interruptible_timeout(&queue->tls_complete, tmo);
-	if (ret <= 0) {
-		if (ret == 0)
-			ret = -ETIMEDOUT;
+	wait_ret = wait_for_completion_interruptible_timeout(&queue->tls_complete,
+							     tmo);
+	if (wait_ret <= 0) {
+		ret = wait_ret < 0 ? -ERESTARTSYS : -ETIMEDOUT;
 
 		dev_err(nctrl->device,
 			"queue %d: TLS handshake failed, error %d\n",
-- 
2.43.0

Re: [PATCH v3 2/2] nvme-tcp: validate the TLS handshake timeout

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>