path: root/drivers/tee/tee_shm.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015-2017, 2019-2021 Linaro Limited
 */
#include <linux/anon_inodes.h>
#include <linux/device.h>
#include <linux/idr.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/tee_core.h>
#include <linux/uaccess.h>
#include <linux/uio.h>
#include <linux/highmem.h>
#include "tee_private.h"

static void shm_put_kernel_pages(struct page **pages, size_t page_count)
{
	size_t n;

	for (n = 0; n < page_count; n++)
		put_page(pages[n]);
}

static void shm_get_kernel_pages(struct page **pages, size_t page_count)
{
	size_t n;

	for (n = 0; n < page_count; n++)
		get_page(pages[n]);
}

static void release_registered_pages(struct tee_shm *shm)
{
	if (shm->pages) {
		if (shm->flags & TEE_SHM_USER_MAPPED)
			unpin_user_pages(shm->pages, shm->num_pages);
		else
			shm_put_kernel_pages(shm->pages, shm->num_pages);

		kfree(shm->pages);
	}
}

static void tee_shm_release(struct tee_device *teedev, struct tee_shm *shm)
{
	if (shm->flags & TEE_SHM_POOL) {
		teedev->pool->ops->free(teedev->pool, shm);
	} else if (shm->flags & TEE_SHM_DYNAMIC) {
		int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);

		if (rc)
			dev_err(teedev->dev.parent,
				"unregister shm %p failed: %d", shm, rc);

		release_registered_pages(shm);
	}

	teedev_ctx_put(shm->ctx);

	kfree(shm);

	tee_device_put(teedev);
}

static struct tee_shm *shm_alloc_helper(struct tee_context *ctx, size_t size,
					size_t align, u32 flags, int id)
{
	struct tee_device *teedev = ctx->teedev;
	struct tee_shm *shm;
	void *ret;
	int rc;

	if (!tee_device_get(teedev))
		return ERR_PTR(-EINVAL);

	if (!teedev->pool) {
		/* teedev has been detached from driver */
		ret = ERR_PTR(-EINVAL);
		goto err_dev_put;
	}

	shm = kzalloc(sizeof(*shm), GFP_KERNEL);
	if (!shm) {
		ret = ERR_PTR(-ENOMEM);
		goto err_dev_put;
	}

	refcount_set(&shm->refcount, 1);
	shm->flags = flags;
	shm->id = id;

	/*
	 * We're assigning this as it is needed if the shm is to be
	 * registered. If this function returns OK then the caller expected
	 * to call teedev_ctx_get() or clear shm->ctx in case it's not
	 * needed any longer.
	 */
	shm->ctx = ctx;

	rc = teedev->pool->ops->alloc(teedev->pool, shm, size, align);
	if (rc) {
		ret = ERR_PTR(rc);
		goto err_kfree;
	}

	teedev_ctx_get(ctx);
	return shm;
err_kfree:
	kfree(shm);
err_dev_put:
	tee_device_put(teedev);
	return ret;
}

/**
 * tee_shm_alloc_user_buf() - Allocate shared memory for user space
 * @ctx:	Context that allocates the shared memory
 * @size:	Requested size of shared memory
 *
 * Memory allocated as user space shared memory is automatically freed when
 * the TEE file pointer is closed. The primary usage of this function is
 * when the TEE driver doesn't support registering ordinary user space
 * memory.
 *
 * @returns a pointer to 'struct tee_shm'
 */
struct tee_shm *tee_shm_alloc_user_buf(struct tee_context *ctx, size_t size)
{
	u32 flags = TEE_SHM_DYNAMIC | TEE_SHM_POOL;
	struct tee_device *teedev = ctx->teedev;
	struct tee_shm *shm;
	void *ret;
	int id;

	mutex_lock(&teedev->mutex);
	id = idr_alloc(&teedev->idr, NULL, 1, 0, GFP_KERNEL);
	mutex_unlock(&teedev->mutex);
	if (id < 0)
		return ERR_PTR(id);

	shm = shm_alloc_helper(ctx, size, PAGE_SIZE, flags, id);
	if (IS_ERR(shm)) {
		mutex_lock(&teedev->mutex);
		idr_remove(&teedev->idr, id);
		mutex_unlock(&teedev->mutex);
		return shm;
	}

	mutex_lock(&teedev->mutex);
	ret = idr_replace(&teedev->idr, shm, id);
	mutex_unlock(&teedev->mutex);
	if (IS_ERR(ret)) {
		tee_shm_free(shm);
		return ret;
	}

	return shm;
}

/**
 * tee_shm_alloc_kernel_buf() - Allocate shared memory for kernel buffer
 * @ctx:	Context that allocates the shared memory
 * @size:	Requested size of shared memory
 *
 * The returned memory registered in secure world and is suitable to be
 * passed as a memory buffer in parameter argument to
 * tee_client_invoke_func(). The memory allocated is later freed with a
 * call to tee_shm_free().
 *
 * @returns a pointer to 'struct tee_shm'
 */
struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size)
{
	u32 flags = TEE_SHM_DYNAMIC | TEE_SHM_POOL;

	return shm_alloc_helper(ctx, size, PAGE_SIZE, flags, -1);
}
EXPORT_SYMBOL_GPL(tee_shm_alloc_kernel_buf);

/**
 * tee_shm_alloc_priv_buf() - Allocate shared memory for a privately shared
 *			      kernel buffer
 * @ctx:	Context that allocates the shared memory
 * @size:	Requested size of shared memory
 *
 * This function returns similar shared memory as
 * tee_shm_alloc_kernel_buf(), but with the difference that the memory
 * might not be registered in secure world in case the driver supports
 * passing memory not registered in advance.
 *
 * This function should normally only be used internally in the TEE
 * drivers.
 *
 * @returns a pointer to 'struct tee_shm'
 */
struct tee_shm *tee_shm_alloc_priv_buf(struct tee_context *ctx, size_t size)
{
	u32 flags = TEE_SHM_PRIV | TEE_SHM_POOL;

	return shm_alloc_helper(ctx, size, sizeof(long) * 2, flags, -1);
}
EXPORT_SYMBOL_GPL(tee_shm_alloc_priv_buf);

int tee_dyn_shm_alloc_helper(struct tee_shm *shm, size_t size, size_t align,
			     int (*shm_register)(struct tee_context *ctx,
						 struct tee_shm *shm,
						 struct page **pages,
						 size_t num_pages,
						 unsigned long start))
{
	size_t nr_pages = roundup(size, PAGE_SIZE) / PAGE_SIZE;
	struct page **pages;
	unsigned int i;
	int rc = 0;

	/*
	 * Ignore alignment since this is already going to be page aligned
	 * and there's no need for any larger alignment.
	 */
	shm->kaddr = alloc_pages_exact(nr_pages * PAGE_SIZE,
				       GFP_KERNEL | __GFP_ZERO);
	if (!shm->kaddr)
		return -ENOMEM;

	shm->paddr = virt_to_phys(shm->kaddr);
	shm->size = nr_pages * PAGE_SIZE;

	pages = kcalloc(nr_pages, sizeof(*pages), GFP_KERNEL);
	if (!pages) {
		rc = -ENOMEM;
		goto err;
	}

	for (i = 0; i < nr_pages; i++)
		pages[i] = virt_to_page((u8 *)shm->kaddr + i * PAGE_SIZE);

	shm->pages = pages;
	shm->num_pages = nr_pages;

	if (shm_register) {
		rc = shm_register(shm->ctx, shm, pages, nr_pages,
				  (unsigned long)shm->kaddr);
		if (rc)
			goto err;
	}

	return 0;
err:
	free_pages_exact(shm->kaddr, shm->size);
	shm->kaddr = NULL;
	return rc;
}
EXPORT_SYMBOL_GPL(tee_dyn_shm_alloc_helper);

void tee_dyn_shm_free_helper(struct tee_shm *shm,
			     int (*shm_unregister)(struct tee_context *ctx,
						   struct tee_shm *shm))
{
	if (shm_unregister)
		shm_unregister(shm->ctx, shm);
	free_pages_exact(shm->kaddr, shm->size);
	shm->kaddr = NULL;
	kfree(shm->pages);
	shm->pages = NULL;
}
EXPORT_SYMBOL_GPL(tee_dyn_shm_free_helper);

static struct tee_shm *
register_shm_helper(struct tee_context *ctx, struct iov_iter *iter, u32 flags,
		    int id)
{
	struct tee_device *teedev = ctx->teedev;
	struct tee_shm *shm;
	unsigned long start, addr;
	size_t num_pages, off;
	ssize_t len;
	void *ret;
	int rc;

	if (!tee_device_get(teedev))
		return ERR_PTR(-EINVAL);

	if (!teedev->desc->ops->shm_register ||
	    !teedev->desc->ops->shm_unregister) {
		ret = ERR_PTR(-ENOTSUPP);
		goto err_dev_put;
	}

	teedev_ctx_get(ctx);

	shm = kzalloc(sizeof(*shm), GFP_KERNEL);
	if (!shm) {
		ret = ERR_PTR(-ENOMEM);
		goto err_ctx_put;
	}

	refcount_set(&shm->refcount, 1);
	shm->flags = flags;
	shm->ctx = ctx;
	shm->id = id;
	addr = untagged_addr((unsigned long)iter_iov_addr(iter));
	start = rounddown(addr, PAGE_SIZE);
	num_pages = iov_iter_npages(iter, INT_M