Merge tag 'armsoc-tee' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc

Pull TEE driver infrastructure and OP-TEE drivers from Arnd Bergmann:
 "This introduces a generic TEE framework in the kernel, to handle
  trusted environemtns (security coprocessor or software implementations
  such as OP-TEE/TrustZone). I'm sending it separately from the other
  arm-soc driver changes to give it a little more visibility, once the
  subsystem is merged, we will likely keep this in the arm₋soc drivers
  branch or have the maintainers submit pull requests directly,
  depending on the patch volume.

  I have reviewed earlier versions in the past, and have reviewed the
  latest version in person during Linaro Connect BUD17.

  Here is my overall assessment of the subsystem:

   - There is clearly demand for this, both for the generic
     infrastructure and the specific OP-TEE implementation.

   - The code has gone through a large number of reviews, and the review
     comments have all been addressed, but the reviews were not coming
     up with serious issues any more and nobody volunteered to vouch for
     the quality.

   - The user space ioctl interface is sufficient to work with the
     OP-TEE driver, and it should in principle work with other TEE
     implementations that follow the GlobalPlatform[1] standards, but it
     might need to be extended in minor ways depending on specific
     requirements of future TEE implementations

   - The main downside of the API to me is how the user space is tied to
     the TEE implementation in hardware or firmware, but uses a generic
     way to communicate with it. This seems to be an inherent problem
     with what it is trying to do, and I could not come up with any
     better solution than what is implemented here.

  For a detailed history of the patch series, see

    https://lkml.org/lkml/2017/3/10/1277"

* tag 'armsoc-tee' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  arm64: dt: hikey: Add optee node
  Documentation: tee subsystem and op-tee driver
  tee: add OP-TEE driver
  tee: generic TEE subsystem
  dt/bindings: add bindings for optee

1 files changed, 273 insertions, 0 deletions

diff --git a/drivers/tee/optee/supp.c b/drivers/tee/optee/supp.c
new file mode 100644
index 000000000000..b4ea0678a436
--- /dev/null
+++ b/drivers/tee/optee/supp.c
@@ -0,0 +1,273 @@
+/*
+ * Copyright (c) 2015, Linaro Limited
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include "optee_private.h"
+
+void optee_supp_init(struct optee_supp *supp)
+{
+	memset(supp, 0, sizeof(*supp));
+	mutex_init(&supp->ctx_mutex);
+	mutex_init(&supp->thrd_mutex);
+	mutex_init(&supp->supp_mutex);
+	init_completion(&supp->data_to_supp);
+	init_completion(&supp->data_from_supp);
+}
+
+void optee_supp_uninit(struct optee_supp *supp)
+{
+	mutex_destroy(&supp->ctx_mutex);
+	mutex_destroy(&supp->thrd_mutex);
+	mutex_destroy(&supp->supp_mutex);
+}
+
+/**
+ * optee_supp_thrd_req() - request service from supplicant
+ * @ctx:	context doing the request
+ * @func:	function requested
+ * @num_params:	number of elements in @param array
+ * @param:	parameters for function
+ *
+ * Returns result of operation to be passed to secure world
+ */
+u32 optee_supp_thrd_req(struct tee_context *ctx, u32 func, size_t num_params,
+			struct tee_param *param)
+{
+	bool interruptable;
+	struct optee *optee = tee_get_drvdata(ctx->teedev);
+	struct optee_supp *supp = &optee->supp;
+	u32 ret;
+
+	/*
+	 * Other threads blocks here until we've copied our answer from
+	 * supplicant.
+	 */
+	while (mutex_lock_interruptible(&supp->thrd_mutex)) {
+		/* See comment below on when the RPC can be interrupted. */
+		mutex_lock(&supp->ctx_mutex);
+		interruptable = !supp->ctx;
+		mutex_unlock(&supp->ctx_mutex);
+		if (interruptable)
+			return TEEC_ERROR_COMMUNICATION;
+	}
+
+	/*
+	 * We have exclusive access now since the supplicant at this
+	 * point is either doing a
+	 * wait_for_completion_interruptible(&supp->data_to_supp) or is in
+	 * userspace still about to do the ioctl() to enter
+	 * optee_supp_recv() below.
+	 */
+
+	supp->func = func;
+	supp->num_params = num_params;
+	supp->param = param;
+	supp->req_posted = true;
+
+	/* Let supplicant get the data */
+	complete(&supp->data_to_supp);
+
+	/*
+	 * Wait for supplicant to process and return result, once we've
+	 * returned from wait_for_completion(data_from_supp) we have
+	 * exclusive access again.
+	 */
+	while (wait_for_completion_interruptible(&supp->data_from_supp)) {
+		mutex_lock(&supp->ctx_mutex);
+		interruptable = !supp->ctx;
+		if (interruptable) {
+			/*
+			 * There's no supplicant available and since the
+			 * supp->ctx_mutex currently is held none can
+			 * become available until the mutex released
+			 * again.
+			 *
+			 * Interrupting an RPC to supplicant is only
+			 * allowed as a way of slightly improving the user
+			 * experience in case the supplicant hasn't been
+			 * started yet. During normal operation the supplicant
+			 * will serve all requests in a timely manner and
+			 * interrupting then wouldn't make sense.
+			 */
+			supp->ret = TEEC_ERROR_COMMUNICATION;
+			init_completion(&supp->data_to_supp);
+		}
+		mutex_unlock(&supp->ctx_mutex);
+		if (interruptable)
+			break;
+	}
+
+	ret = supp->ret;
+	supp->param = NULL;
+	supp->req_posted = false;
+
+	/* We're done, let someone else talk to the supplicant now. */
+	mutex_unlock(&supp->thrd_mutex);
+
+	return ret;
+}
+
+/**
+ * optee_supp_recv() - receive request for supplicant
+ * @ctx:	context receiving the request
+ * @func:	requested function in supplicant
+ * @num_params:	number of elements allocated in @param, updated with number
+ *		used elements
+ * @param:	space for parameters for @func
+ *
+ * Returns 0 on success or <0 on failure
+ */
+int optee_supp_recv(struct tee_context *ctx, u32 *func, u32 *num_params,
+		    struct tee_param *param)
+{
+	struct tee_device *teedev = ctx->teedev;
+	struct optee *optee = tee_get_drvdata(teedev);
+	struct optee_supp *supp = &optee->supp;
+	int rc;
+
+	/*
+	 * In case two threads in one supplicant is calling this function
+	 * simultaneously we need to protect the data with a mutex which
+	 * we'll release before returning.
+	 */
+	mutex_lock(&supp->supp_mutex);
+
+	if (supp->supp_next_send) {
+		/*
+		 * optee_supp_recv() has been called again without
+		 * a optee_supp_send() in between. Supplicant has
+		 * probably been restarted before it was able to
+		 * write back last result. Abort last request and
+		 * wait for a new.
+		 */
+		if (supp->req_posted) {
+			supp->ret = TEEC_ERROR_COMMUNICATION;
+			supp->supp_next_send = false;
+			complete(&supp->data_from_supp);
+		}
+	}
+
+	/*
+	 * This is where supplicant will be hanging most of the
+	 * time, let's make this interruptable so we can easily
+	 * restart supplicant if needed.
+	 */
+	if (wait_for_completion_interruptible(&supp->data_to_supp)) {
+		rc = -ERESTARTSYS;
+		goto out;
+	}
+
+	/* We have exlusive access to the data */
+
+	if (*num_params < supp->num_params) {
+		/*
+		 * Not enough room for parameters, tell supplicant
+		 * it failed and abort last request.
+		 */
+		supp->ret = TEEC_ERROR_COMMUNICATION;
+		rc = -EINVAL;
+		complete(&supp->data_from_supp);
+		goto out;
+	}
+
+	*func = supp->func;
+	*num_params = supp->num_params;
+	memcpy(param, supp->param,
+	       sizeof(struct tee_param) * supp->num_params);
+
+	/* Allow optee_supp_send() below to do its work */
+	supp->supp_next_send = true;
+
+	rc = 0;
+out:
+	mutex_unlock(&supp->supp_mutex);
+	return rc;
+}
+
+/**
+ * optee_supp_send() - send result of request from supplicant
+ * @ctx:	context sending result
+ * @ret:	return value of request
+ * @num_params:	number of parameters returned
+ * @param:	returned parameters
+ *
+ * Returns 0 on success or <0 on failure.
+ */
+int optee_supp_send(struct tee_context *ctx, u32 ret, u32 num_params,
+		    struct tee_param *param)
+{
+	struct tee_device *teedev = ctx->teedev;
+	struct optee *optee = tee_get_drvdata(teedev);
+	struct optee_supp *supp = &optee->supp;
+	size_t n;
+	int rc = 0;
+
+	/*
+	 * We still have exclusive access to the data since that's how we
+	 * left it when returning from optee_supp_read().
+	 */
+
+	/* See comment on mutex in optee_supp_read() above */
+	mutex_lock(&supp->supp_mutex);
+
+	if (!supp->supp_next_send) {
+		/*
+		 * Something strange is going on, supplicant shouldn't
+		 * enter optee_supp_send() in this state
+		 */
+		rc = -ENOENT;
+		goto out;
+	}
+
+	if (num_params != supp->num_params) {
+		/*
+		 * Something is wrong, let supplicant restart. Next call to
+		 * optee_supp_recv() will give an error to the requesting
+		 * thread and release it.
+		 */
+		rc = -EINVAL;
+		goto out;
+	}
+
+	/* Update out and in/out parameters */
+	for (n = 0; n < num_params; n++) {
+		struct tee_param *p = supp->param + n;
+
+		switch (p->attr) {
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_INOUT:
+			p->u.value.a = param[n].u.value.a;
+			p->u.value.b = param[n].u.value.b;
+			p->u.value.c = param[n].u.value.c;
+			break;
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_OUTPUT:
+		case TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT:
+			p->u.memref.size = param[n].u.memref.size;
+			break;
+		default:
+			break;
+		}
+	}
+	supp->ret = ret;
+
+	/* Allow optee_supp_recv() above to do its work */
+	supp->supp_next_send = false;
+
+	/* Let the requesting thread continue */
+	complete(&supp->data_from_supp);
+out:
+	mutex_unlock(&supp->supp_mutex);
+	return rc;
+}