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synced 2024-08-28 20:02:17 +00:00
![Jens Wiklander](/assets/img/avatar_default.png)
Since the tee subsystem does not keep a strong reference to its idle
shared memory buffers, it races with other threads that try to destroy a
shared memory through a close of its dma-buf fd or by unmapping the
memory.
In tee_shm_get_from_id() when a lookup in teedev->idr has been
successful, it is possible that the tee_shm is in the dma-buf teardown
path, but that path is blocked by the teedev mutex. Since we don't have
an API to tell if the tee_shm is in the dma-buf teardown path or not we
must find another way of detecting this condition.
Fix this by doing the reference counting directly on the tee_shm using a
new refcount_t refcount field. dma-buf is replaced by using
anon_inode_getfd() instead, this separates the life-cycle of the
underlying file from the tee_shm. tee_shm_put() is updated to hold the
mutex when decreasing the refcount to 0 and then remove the tee_shm from
teedev->idr before releasing the mutex. This means that the tee_shm can
never be found unless it has a refcount larger than 0.
Fixes: 967c9cca2c
("tee: generic TEE subsystem")
Cc: stable@vger.kernel.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Lars Persson <larper@axis.com>
Reviewed-by: Sumit Garg <sumit.garg@linaro.org>
Reported-by: Patrik Lantz <patrik.lantz@axis.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
460 lines
11 KiB
C
460 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (c) 2015-2017, 2019-2021 Linaro Limited
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*/
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#include <linux/anon_inodes.h>
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#include <linux/device.h>
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#include <linux/idr.h>
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/tee_drv.h>
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#include <linux/uio.h>
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#include "tee_private.h"
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static void release_registered_pages(struct tee_shm *shm)
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{
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if (shm->pages) {
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if (shm->flags & TEE_SHM_USER_MAPPED) {
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unpin_user_pages(shm->pages, shm->num_pages);
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} else {
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size_t n;
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for (n = 0; n < shm->num_pages; n++)
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put_page(shm->pages[n]);
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}
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kfree(shm->pages);
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}
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}
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static void tee_shm_release(struct tee_device *teedev, struct tee_shm *shm)
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{
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if (shm->flags & TEE_SHM_POOL) {
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struct tee_shm_pool_mgr *poolm;
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if (shm->flags & TEE_SHM_DMA_BUF)
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poolm = teedev->pool->dma_buf_mgr;
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else
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poolm = teedev->pool->private_mgr;
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poolm->ops->free(poolm, shm);
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} else if (shm->flags & TEE_SHM_REGISTER) {
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int rc = teedev->desc->ops->shm_unregister(shm->ctx, shm);
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if (rc)
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dev_err(teedev->dev.parent,
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"unregister shm %p failed: %d", shm, rc);
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release_registered_pages(shm);
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}
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teedev_ctx_put(shm->ctx);
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kfree(shm);
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tee_device_put(teedev);
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}
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struct tee_shm *tee_shm_alloc(struct tee_context *ctx, size_t size, u32 flags)
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{
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struct tee_device *teedev = ctx->teedev;
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struct tee_shm_pool_mgr *poolm = NULL;
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struct tee_shm *shm;
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void *ret;
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int rc;
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if (!(flags & TEE_SHM_MAPPED)) {
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dev_err(teedev->dev.parent,
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"only mapped allocations supported\n");
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return ERR_PTR(-EINVAL);
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}
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if ((flags & ~(TEE_SHM_MAPPED | TEE_SHM_DMA_BUF | TEE_SHM_PRIV))) {
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dev_err(teedev->dev.parent, "invalid shm flags 0x%x", flags);
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return ERR_PTR(-EINVAL);
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}
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if (!tee_device_get(teedev))
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return ERR_PTR(-EINVAL);
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if (!teedev->pool) {
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/* teedev has been detached from driver */
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ret = ERR_PTR(-EINVAL);
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goto err_dev_put;
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}
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shm = kzalloc(sizeof(*shm), GFP_KERNEL);
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if (!shm) {
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ret = ERR_PTR(-ENOMEM);
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goto err_dev_put;
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}
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refcount_set(&shm->refcount, 1);
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shm->flags = flags | TEE_SHM_POOL;
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shm->ctx = ctx;
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if (flags & TEE_SHM_DMA_BUF)
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poolm = teedev->pool->dma_buf_mgr;
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else
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poolm = teedev->pool->private_mgr;
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rc = poolm->ops->alloc(poolm, shm, size);
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if (rc) {
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ret = ERR_PTR(rc);
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goto err_kfree;
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}
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if (flags & TEE_SHM_DMA_BUF) {
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mutex_lock(&teedev->mutex);
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shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
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mutex_unlock(&teedev->mutex);
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if (shm->id < 0) {
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ret = ERR_PTR(shm->id);
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goto err_pool_free;
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}
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}
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teedev_ctx_get(ctx);
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return shm;
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err_pool_free:
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poolm->ops->free(poolm, shm);
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err_kfree:
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kfree(shm);
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err_dev_put:
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tee_device_put(teedev);
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return ret;
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}
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EXPORT_SYMBOL_GPL(tee_shm_alloc);
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/**
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* tee_shm_alloc_kernel_buf() - Allocate shared memory for kernel buffer
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* @ctx: Context that allocates the shared memory
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* @size: Requested size of shared memory
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*
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* The returned memory registered in secure world and is suitable to be
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* passed as a memory buffer in parameter argument to
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* tee_client_invoke_func(). The memory allocated is later freed with a
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* call to tee_shm_free().
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*
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* @returns a pointer to 'struct tee_shm'
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*/
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struct tee_shm *tee_shm_alloc_kernel_buf(struct tee_context *ctx, size_t size)
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{
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return tee_shm_alloc(ctx, size, TEE_SHM_MAPPED);
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}
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EXPORT_SYMBOL_GPL(tee_shm_alloc_kernel_buf);
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struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
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size_t length, u32 flags)
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{
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struct tee_device *teedev = ctx->teedev;
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const u32 req_user_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
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const u32 req_kernel_flags = TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED;
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struct tee_shm *shm;
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void *ret;
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int rc;
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int num_pages;
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unsigned long start;
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if (flags != req_user_flags && flags != req_kernel_flags)
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return ERR_PTR(-ENOTSUPP);
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if (!tee_device_get(teedev))
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return ERR_PTR(-EINVAL);
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if (!teedev->desc->ops->shm_register ||
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!teedev->desc->ops->shm_unregister) {
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tee_device_put(teedev);
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return ERR_PTR(-ENOTSUPP);
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}
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teedev_ctx_get(ctx);
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shm = kzalloc(sizeof(*shm), GFP_KERNEL);
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if (!shm) {
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ret = ERR_PTR(-ENOMEM);
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goto err;
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}
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refcount_set(&shm->refcount, 1);
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shm->flags = flags | TEE_SHM_REGISTER;
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shm->ctx = ctx;
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shm->id = -1;
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addr = untagged_addr(addr);
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start = rounddown(addr, PAGE_SIZE);
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shm->offset = addr - start;
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shm->size = length;
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num_pages = (roundup(addr + length, PAGE_SIZE) - start) / PAGE_SIZE;
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shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL);
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if (!shm->pages) {
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ret = ERR_PTR(-ENOMEM);
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goto err;
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}
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if (flags & TEE_SHM_USER_MAPPED) {
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rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
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shm->pages);
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} else {
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struct kvec *kiov;
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int i;
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kiov = kcalloc(num_pages, sizeof(*kiov), GFP_KERNEL);
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if (!kiov) {
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ret = ERR_PTR(-ENOMEM);
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goto err;
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}
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for (i = 0; i < num_pages; i++) {
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kiov[i].iov_base = (void *)(start + i * PAGE_SIZE);
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kiov[i].iov_len = PAGE_SIZE;
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}
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rc = get_kernel_pages(kiov, num_pages, 0, shm->pages);
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kfree(kiov);
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}
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if (rc > 0)
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shm->num_pages = rc;
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if (rc != num_pages) {
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if (rc >= 0)
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rc = -ENOMEM;
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ret = ERR_PTR(rc);
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goto err;
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}
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mutex_lock(&teedev->mutex);
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shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
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mutex_unlock(&teedev->mutex);
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if (shm->id < 0) {
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ret = ERR_PTR(shm->id);
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goto err;
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}
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rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
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shm->num_pages, start);
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if (rc) {
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ret = ERR_PTR(rc);
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goto err;
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}
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return shm;
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err:
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if (shm) {
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if (shm->id >= 0) {
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mutex_lock(&teedev->mutex);
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idr_remove(&teedev->idr, shm->id);
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mutex_unlock(&teedev->mutex);
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}
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release_registered_pages(shm);
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}
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kfree(shm);
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teedev_ctx_put(ctx);
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tee_device_put(teedev);
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return ret;
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}
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EXPORT_SYMBOL_GPL(tee_shm_register);
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static int tee_shm_fop_release(struct inode *inode, struct file *filp)
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{
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tee_shm_put(filp->private_data);
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return 0;
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}
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static int tee_shm_fop_mmap(struct file *filp, struct vm_area_struct *vma)
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{
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struct tee_shm *shm = filp->private_data;
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size_t size = vma->vm_end - vma->vm_start;
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/* Refuse sharing shared memory provided by application */
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if (shm->flags & TEE_SHM_USER_MAPPED)
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return -EINVAL;
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/* check for overflowing the buffer's size */
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if (vma->vm_pgoff + vma_pages(vma) > shm->size >> PAGE_SHIFT)
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return -EINVAL;
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return remap_pfn_range(vma, vma->vm_start, shm->paddr >> PAGE_SHIFT,
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size, vma->vm_page_prot);
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}
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static const struct file_operations tee_shm_fops = {
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.owner = THIS_MODULE,
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.release = tee_shm_fop_release,
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.mmap = tee_shm_fop_mmap,
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};
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/**
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* tee_shm_get_fd() - Increase reference count and return file descriptor
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* @shm: Shared memory handle
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* @returns user space file descriptor to shared memory
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*/
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int tee_shm_get_fd(struct tee_shm *shm)
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{
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int fd;
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if (!(shm->flags & TEE_SHM_DMA_BUF))
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return -EINVAL;
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/* matched by tee_shm_put() in tee_shm_op_release() */
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refcount_inc(&shm->refcount);
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fd = anon_inode_getfd("tee_shm", &tee_shm_fops, shm, O_RDWR);
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if (fd < 0)
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tee_shm_put(shm);
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return fd;
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}
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/**
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* tee_shm_free() - Free shared memory
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* @shm: Handle to shared memory to free
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*/
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void tee_shm_free(struct tee_shm *shm)
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{
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tee_shm_put(shm);
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}
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EXPORT_SYMBOL_GPL(tee_shm_free);
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/**
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* tee_shm_va2pa() - Get physical address of a virtual address
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* @shm: Shared memory handle
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* @va: Virtual address to tranlsate
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* @pa: Returned physical address
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* @returns 0 on success and < 0 on failure
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*/
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int tee_shm_va2pa(struct tee_shm *shm, void *va, phys_addr_t *pa)
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{
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if (!(shm->flags & TEE_SHM_MAPPED))
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return -EINVAL;
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/* Check that we're in the range of the shm */
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if ((char *)va < (char *)shm->kaddr)
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return -EINVAL;
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if ((char *)va >= ((char *)shm->kaddr + shm->size))
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return -EINVAL;
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return tee_shm_get_pa(
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shm, (unsigned long)va - (unsigned long)shm->kaddr, pa);
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}
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EXPORT_SYMBOL_GPL(tee_shm_va2pa);
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/**
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* tee_shm_pa2va() - Get virtual address of a physical address
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* @shm: Shared memory handle
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* @pa: Physical address to tranlsate
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* @va: Returned virtual address
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* @returns 0 on success and < 0 on failure
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*/
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int tee_shm_pa2va(struct tee_shm *shm, phys_addr_t pa, void **va)
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{
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if (!(shm->flags & TEE_SHM_MAPPED))
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return -EINVAL;
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/* Check that we're in the range of the shm */
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if (pa < shm->paddr)
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return -EINVAL;
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if (pa >= (shm->paddr + shm->size))
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return -EINVAL;
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if (va) {
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void *v = tee_shm_get_va(shm, pa - shm->paddr);
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if (IS_ERR(v))
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return PTR_ERR(v);
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*va = v;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(tee_shm_pa2va);
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/**
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* tee_shm_get_va() - Get virtual address of a shared memory plus an offset
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* @shm: Shared memory handle
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* @offs: Offset from start of this shared memory
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* @returns virtual address of the shared memory + offs if offs is within
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* the bounds of this shared memory, else an ERR_PTR
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*/
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void *tee_shm_get_va(struct tee_shm *shm, size_t offs)
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{
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if (!(shm->flags & TEE_SHM_MAPPED))
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return ERR_PTR(-EINVAL);
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if (offs >= shm->size)
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return ERR_PTR(-EINVAL);
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return (char *)shm->kaddr + offs;
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}
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EXPORT_SYMBOL_GPL(tee_shm_get_va);
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/**
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* tee_shm_get_pa() - Get physical address of a shared memory plus an offset
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* @shm: Shared memory handle
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* @offs: Offset from start of this shared memory
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* @pa: Physical address to return
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* @returns 0 if offs is within the bounds of this shared memory, else an
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* error code.
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*/
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int tee_shm_get_pa(struct tee_shm *shm, size_t offs, phys_addr_t *pa)
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{
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if (offs >= shm->size)
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return -EINVAL;
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if (pa)
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*pa = shm->paddr + offs;
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return 0;
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}
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EXPORT_SYMBOL_GPL(tee_shm_get_pa);
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/**
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* tee_shm_get_from_id() - Find shared memory object and increase reference
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* count
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* @ctx: Context owning the shared memory
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* @id: Id of shared memory object
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* @returns a pointer to 'struct tee_shm' on success or an ERR_PTR on failure
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*/
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struct tee_shm *tee_shm_get_from_id(struct tee_context *ctx, int id)
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{
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struct tee_device *teedev;
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struct tee_shm *shm;
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if (!ctx)
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return ERR_PTR(-EINVAL);
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teedev = ctx->teedev;
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mutex_lock(&teedev->mutex);
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shm = idr_find(&teedev->idr, id);
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/*
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* If the tee_shm was found in the IDR it must have a refcount
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* larger than 0 due to the guarantee in tee_shm_put() below. So
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* it's safe to use refcount_inc().
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*/
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if (!shm || shm->ctx != ctx)
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shm = ERR_PTR(-EINVAL);
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else
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refcount_inc(&shm->refcount);
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mutex_unlock(&teedev->mutex);
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return shm;
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}
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EXPORT_SYMBOL_GPL(tee_shm_get_from_id);
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/**
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* tee_shm_put() - Decrease reference count on a shared memory handle
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* @shm: Shared memory handle
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*/
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void tee_shm_put(struct tee_shm *shm)
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{
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struct tee_device *teedev = shm->ctx->teedev;
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bool do_release = false;
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mutex_lock(&teedev->mutex);
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if (refcount_dec_and_test(&shm->refcount)) {
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/*
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* refcount has reached 0, we must now remove it from the
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* IDR before releasing the mutex. This will guarantee that
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* the refcount_inc() in tee_shm_get_from_id() never starts
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* from 0.
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*/
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if (shm->flags & TEE_SHM_DMA_BUF)
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idr_remove(&teedev->idr, shm->id);
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do_release = true;
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}
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mutex_unlock(&teedev->mutex);
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if (do_release)
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tee_shm_release(teedev, shm);
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}
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EXPORT_SYMBOL_GPL(tee_shm_put);
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