call.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015-2021, Linaro Limited
 */
#include <linux/device.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/tee_drv.h>
#include <linux/types.h>
#include "optee_private.h"

#define MAX_ARG_PARAM_COUNT	6

/*
 * How much memory we allocate for each entry. This doesn't have to be a
 * single page, but it makes sense to keep at least keep it as multiples of
 * the page size.
 */
#define SHM_ENTRY_SIZE		PAGE_SIZE

/*
 * We need to have a compile time constant to be able to determine the
 * maximum needed size of the bit field.
 */
#define MIN_ARG_SIZE		OPTEE_MSG_GET_ARG_SIZE(MAX_ARG_PARAM_COUNT)
#define MAX_ARG_COUNT_PER_ENTRY	(SHM_ENTRY_SIZE / MIN_ARG_SIZE)

/*
 * Shared memory for argument structs are cached here. The number of
 * arguments structs that can fit is determined at runtime depending on the
 * needed RPC parameter count reported by secure world
 * (optee->rpc_param_count).
 */
struct optee_shm_arg_entry {
	struct list_head list_node;
	struct tee_shm *shm;
	DECLARE_BITMAP(map, MAX_ARG_COUNT_PER_ENTRY);
};

void optee_cq_init(struct optee_call_queue *cq, int thread_count)
{
	mutex_init(&cq->mutex);
	INIT_LIST_HEAD(&cq->waiters);

	/*
	 * If cq->total_thread_count is 0 then we're not trying to keep
	 * track of how many free threads we have, instead we're relying on
	 * the secure world to tell us when we're out of thread and have to
	 * wait for another thread to become available.
	 */
	cq->total_thread_count = thread_count;
	cq->free_thread_count = thread_count;
}

void optee_cq_wait_init(struct optee_call_queue *cq,
			struct optee_call_waiter *w, bool sys_thread)
{
	unsigned int free_thread_threshold;
	bool need_wait = false;

	memset(w, 0, sizeof(*w));

	/*
	 * We're preparing to make a call to secure world. In case we can't
	 * allocate a thread in secure world we'll end up waiting in
	 * optee_cq_wait_for_completion().
	 *
	 * Normally if there's no contention in secure world the call will
	 * complete and we can cleanup directly with optee_cq_wait_final().
	 */
	mutex_lock(&cq->mutex);

	/*
	 * We add ourselves to the queue, but we don't wait. This
	 * guarantees that we don't lose a completion if secure world
	 * returns busy and another thread just exited and try to complete
	 * someone.
	 */
	init_completion(&w->c);
	list_add_tail(&w->list_node, &cq->waiters);
	w->sys_thread = sys_thread;

	if (cq->total_thread_count) {
		if (sys_thread || !cq->sys_thread_req_count)
			free_thread_threshold = 0;
		else
			free_thread_threshold = 1;

		if (cq->free_thread_count > free_thread_threshold)
			cq->free_thread_count--;
		else
			need_wait = true;
	}

	mutex_unlock(&cq->mutex);

	while (need_wait) {
		optee_cq_wait_for_completion(cq, w);
		mutex_lock(&cq->mutex);

		if (sys_thread || !cq->sys_thread_req_count)
			free_thread_threshold = 0;
		else
			free_thread_threshold = 1;

		if (cq->free_thread_count > free_thread_threshold) {
			cq->free_thread_count--;
			need_wait = false;
		}

		mutex_unlock(&cq->mutex);
	}
}

void optee_cq_wait_for_completion(struct optee_call_queue *cq,
				  struct optee_call_waiter *w)
{
	wait_for_completion(&w->c);

	mutex_lock(&cq->mutex);

	/* Move to end of list to get out of the way for other waiters */
	list_del(&w->list_node);
	reinit_completion(&w->c);
	list_add_tail(&w->list_node, &cq->waiters);

	mutex_unlock(&cq->mutex);
}

static void optee_cq_complete_one(struct optee_call_queue *cq)
{
	struct optee_call_waiter *w;

	/* Wake a waiting system session if any, prior to a normal session */
	list_for_each_entry(w, &cq->waiters, list_node) {
		if (w->sys_thread && !completion_done(&w->c)) {
			complete(&w->c);
			return;
		}
	}

	list_for_each_entry(w, &cq->waiters, list_node) {
		if (!completion_done(&w->c)) {
			complete(&w->c);
			break;
		}
	}
}

void optee_cq_wait_final(struct optee_call_queue *cq,
			 struct optee_call_waiter *w)
{
	/*
	 * We're done with the call to secure world. The thread in secure
	 * world that was used for this call is now available for some
	 * other task to use.
	 */
	mutex_lock(&cq->mutex);

	/* Get out of the list */
	list_del(&w->list_node);

	cq->free_thread_count++;

	/* Wake up one eventual waiting task */
	optee_cq_complete_one(cq);

	/*
	 * If we're completed we've got a completion from another task that
	 * was just done with its call to secure world. Since yet another
	 * thread now is available in secure world wake up another eventual
	 * waiting task.
	 */
	if (completion_done(&w->c))
		optee_cq_complete_one(cq);

	mutex_unlock(&cq->mutex);
}

/* Count registered system sessions to reserved a system thread or not */
static bool optee_cq_incr_sys_thread_count(struct optee_call_queue *cq)
{
	if (cq->total_thread_count <= 1)
		return false;

	mutex_lock(&cq->mutex);
	cq->sys_thread_req_count++;
	mutex_unlock(&cq->mutex);

	return true;
}

static void optee_cq_decr_sys_thread_count(struct optee_call_queue *cq)
{
	mutex_lock(&cq->mutex);
	cq->sys_thread_req_count--;
	/* If there's someone waiting, let it resume */
	optee_cq_complete_one(cq);
	mutex_unlock(&cq->mutex);
}

/* Requires the filpstate mutex to be held */
static struct optee_session *find_session(struct optee_context_data *ctxdata,
					  u32 session_id)
{
	struct optee_session *sess;

	list_for_each_entry(sess, &ctxdata->sess_list, list_node)
		if (sess->session_id == session_id)
			return sess;

	return NULL;
}

void optee_shm_arg_cache_init(struct optee *optee, u32 flags)
{
	INIT_LIST_HEAD(&optee->shm_arg_cache.shm_args);
	mutex_init(&optee->shm_arg_cache.mutex);
	optee->shm_arg_cache.flags = flags;
}

void optee_shm_arg_cache_uninit(struct optee *optee)
{
	struct list_head *head = &optee->shm_arg_cache.shm_args;
	struct optee_shm_arg_entry *entry;

	mutex_destroy(&optee->shm_arg_cache.mutex);
	while (!list_empty(head)) {
		entry = list_first_entry(head, struct optee_shm_arg_entry,
					 list_node);
		list_del(&entry->list_node);
		if (find_first_bit(entry->map, MAX_ARG_COUNT_PER_ENTRY) !=
		     MAX_ARG_COUNT_PER_ENTRY) {
			pr_err("Freeing non-free entry\n");
		}
		tee_shm_free(entry->shm);
		kfree(entry);
	}
}

size_t optee_msg_arg_size(size_t rpc_param_count)
{
	size_t sz = OPTEE_MSG_GET_ARG_SIZE(MAX_ARG_PARAM_COUNT);

	if (rpc_param_count)
		sz += OPTEE_MSG_GET_ARG_SIZE(rpc_param_count);

	return sz;
}

/**
 * optee_get_msg_arg() - Provide shared memory for argument struct
 * @ctx:	Caller TEE context
 * @num_params:	Number of parameter to store
 * @entry_ret:	Entry pointer, needed when freeing the buffer
 * @shm_ret:	Shared memory buffer
 * @offs_ret:	Offset of argument strut in shared memory buffer
 *
 * @returns a pointer to the argument struct in memory, else an ERR_PTR
 */
struct optee_msg_arg *optee_get_msg_arg(struct tee_context *ctx,
					size_t num_params,
					struct optee_shm_arg_entry **entry_ret,
					struct tee_shm **shm_ret,
					u_int *offs_ret)
{
	struct optee *optee = tee_get_drvdata(ctx->teedev);
	size_t sz = optee_msg_arg_size(optee->rpc_param_count);
	struct optee_shm_arg_entry *entry;
	struct optee_msg_arg *ma;
	size_t args_per_entry;
	u_long bit;
	u_int offs;
	void *res;

	if (num_params > MAX_ARG_PARAM_COUNT)
		return ERR_PTR(-EINVAL);

	if (optee->shm_arg_cache.flags & OPTEE_SHM_ARG_SHARED)
		args_per_entry = SHM_ENTRY_SIZE / sz;
	else
		args_per_entry = 1;

	mutex_lock(&optee->shm_arg_cache.mutex);
	list_for_each_entry(entry, &optee->shm_arg_cache.shm_args, list_node) {
		bit = find_first_zero_bit(entry->map, MAX_ARG_COUNT_PER_ENTRY);
		if (bit < args_per_entry)
			goto have_entry;
	}

	/*
	 * No entry was found, let's allocate a new.
	 */
	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry) {
		res = ERR_PTR(-ENOMEM);
		goto out;
	}

	if (optee->shm_arg_cache.flags & OPTEE_SHM_ARG_ALLOC_PRIV)
		res = tee_shm_alloc_priv_buf(ctx, SHM_ENTRY_SIZE);
	else
		res = tee_shm_alloc_kernel_buf(ctx, SHM_ENTRY_SIZE);

	if (IS_ERR(res)) {
		kfree(entry);
		goto out;
	}
	entry->shm = res;
	list_add(&entry->list_node, &optee->shm_arg_cache.shm_args);
	bit = 0;

have_entry:
	offs = bit * sz;
	res = tee_shm_get_va(entry->shm, offs);
	if (IS_ERR(res))
		goto out;
	ma = res;
	set_bit(bit, entry->map);
	memset(ma, 0, sz);
	ma->num_params = num_params;
	*entry_ret = entry;
	*shm_ret = entry->shm;
	*offs_ret = offs;
out:
	mutex_unlock(&optee->shm_arg_cache.mutex);
	return res;
}

/**
 * optee_free_msg_arg() - Free previsouly obtained shared memory
 * @ctx:	Caller TEE context
 * @entry:	Pointer returned when the shared memory was obtained
 * @offs:	Offset of shared memory buffer to free
 *
 * This function frees the shared memory obtained with optee_get_msg_arg().
 */
void optee_free_msg_arg(struct tee_context *ctx,
			struct optee_shm_arg_entry *entry, u_int offs)
{
	struct optee *optee = tee_get_drvdata(ctx->teedev);
	size_t sz = optee_msg_arg_size(optee->rpc_param_count);
	u_long bit;

	if (offs > SHM_ENTRY_SIZE || offs % sz) {
		pr_err("Invalid offs %u\n", offs);
		return;
	}
	bit = offs / sz;

	mutex_lock(&optee->shm_arg_cache.mutex);

	if (!test_bit(bit, entry->map))
		pr_err("Bit pos %lu is already free\n", bit);
	clear_bit(bit, entry->map);

	mutex_unlock(&optee->shm_arg_cache.mutex);
}

int optee_open_session(struct tee_context *ctx,
		       struct tee_ioctl_open_session_arg *arg,
		       struct tee_param *param)
{
	struct optee *optee = tee_get_drvdata(ctx->teedev);
	struct optee_context_data *ctxdata = ctx->data;
	struct optee_shm_arg_entry *entry;
	struct tee_shm *shm;
	struct optee_msg_arg *msg_arg;
	struct optee_session *sess = NULL;
	uuid_t client_uuid;
	u_int offs;
	int rc;

	/* +2 for the meta parameters added below */
	msg_arg = optee_get_msg_arg(ctx, arg->num_params + 2,
				    &entry, &shm, &offs);
	if (IS_ERR(msg_arg))
		return PTR_ERR(msg_arg);

	msg_arg->cmd = OPTEE_MSG_CMD_OPEN_SESSION;
	msg_arg->cancel_id = arg->cancel_id;

	/*
	 * Initialize and add the meta parameters needed when opening a
	 * session.
	 */
	msg_arg->params[0].attr = OPTEE_MSG_ATTR_TYPE_VALUE_INPUT |
				  OPTEE_MSG_ATTR_META;
	msg_arg->params[1].attr = OPTEE_MSG_ATTR_TYPE_VALUE_INPUT |
				  OPTEE_MSG_ATTR_META;
	memcpy(&msg_arg->params[0].u.value, arg->uuid, sizeof(arg->uuid));
	msg_arg->params[1].u.value.c = arg->clnt_login;

	rc = tee_session_calc_client_uuid(&client_uuid, arg->clnt_login,
					  arg->clnt_uuid);
	if (rc)
		goto out;
	export_uuid(msg_arg->params[1].u.octets, &client_uuid);

	rc = optee->ops->to_msg_param(optee, msg_arg->params + 2,
				      arg->num_params, param);
	if (rc)
		goto out;

	sess = kzalloc(sizeof(*sess), GFP_KERNEL);
	if (!sess) {
		rc = -ENOMEM;
		goto out;
	}

	if (optee->ops->do_call_with_arg(ctx, shm, offs,
					 sess->use_sys_thread)) {
		msg_arg->ret = TEEC_ERROR_COMMUNICATION;
		msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
	}

	if (msg_arg->ret == TEEC_SUCCESS) {
		/* A new session has been created, add it to the list. */
		sess->session_id = msg_arg->session;
		mutex_lock(&ctxdata->mutex);
		list_add(&sess->list_node, &ctxdata->sess_list);
		mutex_unlock(&ctxdata->mutex);
	} else {
		kfree(sess);
	}

	if (optee->ops->from_msg_param(optee, param, arg->num_params,
				       msg_arg->params + 2)) {
		arg->ret = TEEC_ERROR_COMMUNICATION;
		arg->ret_origin = TEEC_ORIGIN_COMMS;
		/* Close session again to avoid leakage */
		optee_close_session(ctx, msg_arg->session);
	} else {
		arg->session = msg_arg->session;
		arg->ret = msg_arg->ret;
		arg->ret_origin = msg_arg->ret_origin;
	}
out:
	optee_free_msg_arg(ctx, entry, offs);

	return rc;
}

int optee_system_session(struct tee_context *ctx, u32 session)
{
	struct optee *optee = tee_get_drvdata(ctx->teedev);
	struct optee_context_data *ctxdata = ctx->data;
	struct optee_session *sess;
	int rc = -EINVAL;

	mutex_lock(&ctxdata->mutex);

	sess = find_session(ctxdata, session);
	if (sess && (sess->use_sys_thread ||
		     optee_cq_incr_sys_thread_count(&optee->call_queue))) {
		sess->use_sys_thread = true;
		rc = 0;
	}

	mutex_unlock(&ctxdata->mutex);

	return rc;
}

int optee_close_session_helper(struct tee_context *ctx, u32 session,
			       bool system_thread)
{
	struct optee *optee = tee_get_drvdata(ctx->teedev);
	struct optee_shm_arg_entry *entry;
	struct optee_msg_arg *msg_arg;
	struct tee_shm *shm;
	u_int offs;

	msg_arg = optee_get_msg_arg(ctx, 0, &entry, &shm, &offs);
	if (IS_ERR(msg_arg))
		return PTR_ERR(msg_arg);

	msg_arg->cmd = OPTEE_MSG_CMD_CLOSE_SESSION;
	msg_arg->session = session;
	optee->ops->do_call_with_arg(ctx, shm, offs, system_thread);

	optee_free_msg_arg(ctx, entry, offs);

	if (system_thread)
		optee_cq_decr_sys_thread_count(&optee->call_queue);

	return 0;
}

int optee_close_session(struct tee_context *ctx, u32 session)
{
	struct optee_context_data *ctxdata = ctx->data;
	struct optee_session *sess;
	bool system_thread;

	/* Check that the session is valid and remove it from the list */
	mutex_lock(&ctxdata->mutex);
	sess = find_session(ctxdata, session);
	if (sess)
		list_del(&sess->list_node);
	mutex_unlock(&ctxdata->mutex);
	if (!sess)
		return -EINVAL;
	system_thread = sess->use_sys_thread;
	kfree(sess);

	return optee_close_session_helper(ctx, session, system_thread);
}

int optee_invoke_func(struct tee_context *ctx, struct tee_ioctl_invoke_arg *arg,
		      struct tee_param *param)
{
	struct optee *optee = tee_get_drvdata(ctx->teedev);
	struct optee_context_data *ctxdata = ctx->data;
	struct optee_shm_arg_entry *entry;
	struct optee_msg_arg *msg_arg;
	struct optee_session *sess;
	struct tee_shm *shm;
	bool system_thread;
	u_int offs;
	int rc;

	/* Check that the session is valid */
	mutex_lock(&ctxdata->mutex);
	sess = find_session(ctxdata, arg->session);
	if (sess)
		system_thread = sess->use_sys_thread;
	mutex_unlock(&ctxdata->mutex);
	if (!sess)
		return -EINVAL;

	msg_arg = optee_get_msg_arg(ctx, arg->num_params,
				    &entry, &shm, &offs);
	if (IS_ERR(msg_arg))
		return PTR_ERR(msg_arg);
	msg_arg->cmd = OPTEE_MSG_CMD_INVOKE_COMMAND;
	msg_arg->func = arg->func;
	msg_arg->session = arg->session;
	msg_arg->cancel_id = arg->cancel_id;

	rc = optee->ops->to_msg_param(optee, msg_arg->params, arg->num_params,
				      param);
	if (rc)
		goto out;

	if (optee->ops->do_call_with_arg(ctx, shm, offs, system_thread)) {
		msg_arg->ret = TEEC_ERROR_COMMUNICATION;
		msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
	}

	if (optee->ops->from_msg_param(optee, param, arg->num_params,
				       msg_arg->params)) {
		msg_arg->ret = TEEC_ERROR_COMMUNICATION;
		msg_arg->ret_origin = TEEC_ORIGIN_COMMS;
	}

	arg->ret = msg_arg->ret;
	arg->ret_origin = msg_arg->ret_origin;
out:
	optee_free_msg_arg(ctx, entry, offs);
	return rc;
}

int optee_cancel_req(struct tee_context *ctx, u32 cancel_id, u32 session)
{
	struct optee *optee = tee_get_drvdata(ctx->teedev);
	struct optee_context_data *ctxdata = ctx->data;
	struct optee_shm_arg_entry *entry;
	struct optee_msg_arg *msg_arg;
	struct optee_session *sess;
	bool system_thread;
	struct tee_shm *shm;
	u_int offs;

	/* Check that the session is valid */
	mutex_lock(&ctxdata->mutex);
	sess = find_session(ctxdata, session);
	if (sess)
		system_thread = sess->use_sys_thread;
	mutex_unlock(&ctxdata->mutex);
	if (!sess)
		return -EINVAL;

	msg_arg = optee_get_msg_arg(ctx, 0, &entry, &shm, &offs);
	if (IS_ERR(msg_arg))
		return PTR_ERR(msg_arg);

	msg_arg->cmd = OPTEE_MSG_CMD_CANCEL;
	msg_arg->session = session;
	msg_arg->cancel_id = cancel_id;
	optee->ops->do_call_with_arg(ctx, shm, offs, system_thread);

	optee_free_msg_arg(ctx, entry, offs);
	return 0;
}

static bool is_normal_memory(pgprot_t p)
{
#if defined(CONFIG_ARM)
	return (((pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEALLOC) ||
		((pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEBACK));
#elif defined(CONFIG_ARM64)
	return (pgprot_val(p) & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL);
#else
#error "Unsupported architecture"
#endif
}

static int __check_mem_type(struct mm_struct *mm, unsigned long start,
				unsigned long end)
{
	struct vm_area_struct *vma;
	VMA_ITERATOR(vmi, mm, start);

	for_each_vma_range(vmi, vma, end) {
		if (!is_normal_memory(vma->vm_page_prot))
			return -EINVAL;
	}

	return 0;
}

int optee_check_mem_type(unsigned long start, size_t num_pages)
{
	struct mm_struct *mm = current->mm;
	int rc;

	/*
	 * Allow kernel address to register with OP-TEE as kernel
	 * pages are configured as normal memory only.
	 */
	if (virt_addr_valid((void *)start) || is_vmalloc_addr((void *)start))
		return 0;

	mmap_read_lock(mm);
	rc = __check_mem_type(mm, start, start + num_pages * PAGE_SIZE);
	mmap_read_unlock(mm);

	return rc;
}