[PATCH 2/4] nvme: don't allow user space to send fabrics commands

[Christoph Hellwig]

Fabrics command are used to set up and control the NVMe over Fabrics
connection.  We can't let user space programs interfer with that.

Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/nvme/host/ioctl.c | 22 ++++++++++++++++++----
 1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 9a2f0f5ccef57..badbc55d29350 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -11,15 +11,29 @@
 static int nvme_cmd_allowed(struct nvme_ns *ns, struct nvme_command *c,
 		fmode_t mode)
 {
+	/*
+	 * Do not allow anyone to send vendor fabrics commands as they are
+	 * used to manage the fabrics transports and we can't let user space
+	 * processes interfere with that.
+	 */
+	if (c->common.opcode == nvme_fabrics_command) {
+		dev_warn_ratelimited(ns->ctrl->device,
+			"rejecting passthrough of fabrics command 0x%x by %s\n",
+			c->common.opcode, current->comm);
+		return -EINVAL;
+	}
+
+	/*
+	 * Allow privileged processes to pass through any other command.
+	 */
 	if (capable(CAP_SYS_ADMIN))
 		return 0;
 
 	/*
-	 * Do not allow unprivileged processes to send vendor specific or fabrics
-	 * commands as we can't be sure about their effects.
+	 * Do not allow unprivileged processes to send vendor specific commands
+	 * as we can't be sure about their effects.
 	 */
-	if (c->common.opcode >= nvme_cmd_vendor_start ||
-	    c->common.opcode == nvme_fabrics_command)
+	if (c->common.opcode >= nvme_cmd_vendor_start)
 		return -EACCES;
 
 	/*
-- 
2.30.2