linux/drivers/tee/tee_shm.c
Jens Wiklander dfd0743f1d tee: handle lookup of shm with reference count 0
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>
2021-12-16 09:30:14 +01:00

461 lines
11 KiB
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/mm.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/tee_drv.h>
#include <linux/uio.h>
#include "tee_private.h"
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 {
size_t n;
for (n = 0; n < shm->num_pages; n++)
put_page(shm->pages[n]);
}
kfree(shm->pages);
}
}
static void tee_shm_release(struct tee_device *teedev, struct tee_shm *shm)
{
if (shm->flags & TEE_SHM_POOL) {
struct tee_shm_pool_mgr *poolm;
if (shm->flags & TEE_SHM_DMA_BUF)
poolm = teedev->pool->dma_buf_mgr;
else
poolm = teedev->pool->private_mgr;
poolm->ops->free(poolm, shm);
} else if (shm->flags & TEE_SHM_REGISTER) {
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);
}
struct tee_shm *tee_shm_alloc(struct tee_context *ctx, size_t size, u32 flags)
{
struct tee_device *teedev = ctx->teedev;
struct tee_shm_pool_mgr *poolm = NULL;
struct tee_shm *shm;
void *ret;
int rc;
if (!(flags & TEE_SHM_MAPPED)) {
dev_err(teedev->dev.parent,
"only mapped allocations supported\n");
return ERR_PTR(-EINVAL);
}
if ((flags & ~(TEE_SHM_MAPPED | TEE_SHM_DMA_BUF | TEE_SHM_PRIV))) {
dev_err(teedev->dev.parent, "invalid shm flags 0x%x", flags);
return ERR_PTR(-EINVAL);
}
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 | TEE_SHM_POOL;
shm->ctx = ctx;
if (flags & TEE_SHM_DMA_BUF)
poolm = teedev->pool->dma_buf_mgr;
else
poolm = teedev->pool->private_mgr;
rc = poolm->ops->alloc(poolm, shm, size);
if (rc) {
ret = ERR_PTR(rc);
goto err_kfree;
}
if (flags & TEE_SHM_DMA_BUF) {
mutex_lock(&teedev->mutex);
shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
mutex_unlock(&teedev->mutex);
if (shm->id < 0) {
ret = ERR_PTR(shm->id);
goto err_pool_free;
}
}
teedev_ctx_get(ctx);
return shm;
err_pool_free:
poolm->ops->free(poolm, shm);
err_kfree:
kfree(shm);
err_dev_put:
tee_device_put(teedev);
return ret;
}
EXPORT_SYMBOL_GPL(tee_shm_alloc);
/**
* 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)
{
return tee_shm_alloc(ctx, size, TEE_SHM_MAPPED);
}
EXPORT_SYMBOL_GPL(tee_shm_alloc_kernel_buf);
struct tee_shm *tee_shm_register(struct tee_context *ctx, unsigned long addr,
size_t length, u32 flags)
{
struct tee_device *teedev = ctx->teedev;
const u32 req_user_flags = TEE_SHM_DMA_BUF | TEE_SHM_USER_MAPPED;
const u32 req_kernel_flags = TEE_SHM_DMA_BUF | TEE_SHM_KERNEL_MAPPED;
struct tee_shm *shm;
void *ret;
int rc;
int num_pages;
unsigned long start;
if (flags != req_user_flags && flags != req_kernel_flags)
return ERR_PTR(-ENOTSUPP);
if (!tee_device_get(teedev))
return ERR_PTR(-EINVAL);
if (!teedev->desc->ops->shm_register ||
!teedev->desc->ops->shm_unregister) {
tee_device_put(teedev);
return ERR_PTR(-ENOTSUPP);
}
teedev_ctx_get(ctx);
shm = kzalloc(sizeof(*shm), GFP_KERNEL);
if (!shm) {
ret = ERR_PTR(-ENOMEM);
goto err;
}
refcount_set(&shm->refcount, 1);
shm->flags = flags | TEE_SHM_REGISTER;
shm->ctx = ctx;
shm->id = -1;
addr = untagged_addr(addr);
start = rounddown(addr, PAGE_SIZE);
shm->offset = addr - start;
shm->size = length;
num_pages = (roundup(addr + length, PAGE_SIZE) - start) / PAGE_SIZE;
shm->pages = kcalloc(num_pages, sizeof(*shm->pages), GFP_KERNEL);
if (!shm->pages) {
ret = ERR_PTR(-ENOMEM);
goto err;
}
if (flags & TEE_SHM_USER_MAPPED) {
rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
shm->pages);
} else {
struct kvec *kiov;
int i;
kiov = kcalloc(num_pages, sizeof(*kiov), GFP_KERNEL);
if (!kiov) {
ret = ERR_PTR(-ENOMEM);
goto err;
}
for (i = 0; i < num_pages; i++) {
kiov[i].iov_base = (void *)(start + i * PAGE_SIZE);
kiov[i].iov_len = PAGE_SIZE;
}
rc = get_kernel_pages(kiov, num_pages, 0, shm->pages);
kfree(kiov);
}
if (rc > 0)
shm->num_pages = rc;
if (rc != num_pages) {
if (rc >= 0)
rc = -ENOMEM;
ret = ERR_PTR(rc);
goto err;
}
mutex_lock(&teedev->mutex);
shm->id = idr_alloc(&teedev->idr, shm, 1, 0, GFP_KERNEL);
mutex_unlock(&teedev->mutex);
if (shm->id < 0) {
ret = ERR_PTR(shm->id);
goto err;
}
rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
shm->num_pages, start);
if (rc) {
ret = ERR_PTR(rc);
goto err;
}
return shm;
err:
if (shm) {
if (shm->id >= 0) {
mutex_lock(&teedev->mutex);
idr_remove(&teedev->idr, shm->id);
mutex_unlock(&teedev->mutex);
}
release_registered_pages(shm);
}
kfree(shm);
teedev_ctx_put(ctx);
tee_device_put(teedev);
return ret;
}
EXPORT_SYMBOL_GPL(tee_shm_register);
static int tee_shm_fop_release(struct inode *inode, struct file *filp)
{
tee_shm_put(filp->private_data);
return 0;
}
static int tee_shm_fop_mmap(struct file *filp, struct vm_area_struct *vma)
{
struct tee_shm *shm = filp->private_data;
size_t size = vma->vm_end - vma->vm_start;
/* Refuse sharing shared memory provided by application */
if (shm->flags & TEE_SHM_USER_MAPPED)
return -EINVAL;
/* check for overflowing the buffer's size */
if (vma->vm_pgoff + vma_pages(vma) > shm->size >> PAGE_SHIFT)
return -EINVAL;
return remap_pfn_range(vma, vma->vm_start, shm->paddr >> PAGE_SHIFT,
size, vma->vm_page_prot);
}
static const struct file_operations tee_shm_fops = {
.owner = THIS_MODULE,
.release = tee_shm_fop_release,
.mmap = tee_shm_fop_mmap,
};
/**
* tee_shm_get_fd() - Increase reference count and return file descriptor
* @shm: Shared memory handle
* @returns user space file descriptor to shared memory
*/
int tee_shm_get_fd(struct tee_shm *shm)
{
int fd;
if (!(shm->flags & TEE_SHM_DMA_BUF))
return -EINVAL;
/* matched by tee_shm_put() in tee_shm_op_release() */
refcount_inc(&shm->refcount);
fd = anon_inode_getfd("tee_shm", &tee_shm_fops, shm, O_RDWR);
if (fd < 0)
tee_shm_put(shm);
return fd;
}
/**
* tee_shm_free() - Free shared memory
* @shm: Handle to shared memory to free
*/
void tee_shm_free(struct tee_shm *shm)
{
tee_shm_put(shm);
}
EXPORT_SYMBOL_GPL(tee_shm_free);
/**
* tee_shm_va2pa() - Get physical address of a virtual address
* @shm: Shared memory handle
* @va: Virtual address to tranlsate
* @pa: Returned physical address
* @returns 0 on success and < 0 on failure
*/
int tee_shm_va2pa(struct tee_shm *shm, void *va, phys_addr_t *pa)
{
if (!(shm->flags & TEE_SHM_MAPPED))
return -EINVAL;
/* Check that we're in the range of the shm */
if ((char *)va < (char *)shm->kaddr)
return -EINVAL;
if ((char *)va >= ((char *)shm->kaddr + shm->size))
return -EINVAL;
return tee_shm_get_pa(
shm, (unsigned long)va - (unsigned long)shm->kaddr, pa);
}
EXPORT_SYMBOL_GPL(tee_shm_va2pa);
/**
* tee_shm_pa2va() - Get virtual address of a physical address
* @shm: Shared memory handle
* @pa: Physical address to tranlsate
* @va: Returned virtual address
* @returns 0 on success and < 0 on failure
*/
int tee_shm_pa2va(struct tee_shm *shm, phys_addr_t pa, void **va)
{
if (!(shm->flags & TEE_SHM_MAPPED))
return -EINVAL;
/* Check that we're in the range of the shm */
if (pa < shm->paddr)
return -EINVAL;
if (pa >= (shm->paddr + shm->size))
return -EINVAL;
if (va) {
void *v = tee_shm_get_va(shm, pa - shm->paddr);
if (IS_ERR(v))
return PTR_ERR(v);
*va = v;
}
return 0;
}
EXPORT_SYMBOL_GPL(tee_shm_pa2va);
/**
* tee_shm_get_va() - Get virtual address of a shared memory plus an offset
* @shm: Shared memory handle
* @offs: Offset from start of this shared memory
* @returns virtual address of the shared memory + offs if offs is within
* the bounds of this shared memory, else an ERR_PTR
*/
void *tee_shm_get_va(struct tee_shm *shm, size_t offs)
{
if (!(shm->flags & TEE_SHM_MAPPED))
return ERR_PTR(-EINVAL);
if (offs >= shm->size)
return ERR_PTR(-EINVAL);
return (char *)shm->kaddr + offs;
}
EXPORT_SYMBOL_GPL(tee_shm_get_va);
/**
* tee_shm_get_pa() - Get physical address of a shared memory plus an offset
* @shm: Shared memory handle
* @offs: Offset from start of this shared memory
* @pa: Physical address to return
* @returns 0 if offs is within the bounds of this shared memory, else an
* error code.
*/
int tee_shm_get_pa(struct tee_shm *shm, size_t offs, phys_addr_t *pa)
{
if (offs >= shm->size)
return -EINVAL;
if (pa)
*pa = shm->paddr + offs;
return 0;
}
EXPORT_SYMBOL_GPL(tee_shm_get_pa);
/**
* tee_shm_get_from_id() - Find shared memory object and increase reference
* count
* @ctx: Context owning the shared memory
* @id: Id of shared memory object
* @returns a pointer to 'struct tee_shm' on success or an ERR_PTR on failure
*/
struct tee_shm *tee_shm_get_from_id(struct tee_context *ctx, int id)
{
struct tee_device *teedev;
struct tee_shm *shm;
if (!ctx)
return ERR_PTR(-EINVAL);
teedev = ctx->teedev;
mutex_lock(&teedev->mutex);
shm = idr_find(&teedev->idr, id);
/*
* If the tee_shm was found in the IDR it must have a refcount
* larger than 0 due to the guarantee in tee_shm_put() below. So
* it's safe to use refcount_inc().
*/
if (!shm || shm->ctx != ctx)
shm = ERR_PTR(-EINVAL);
else
refcount_inc(&shm->refcount);
mutex_unlock(&teedev->mutex);
return shm;
}
EXPORT_SYMBOL_GPL(tee_shm_get_from_id);
/**
* tee_shm_put() - Decrease reference count on a shared memory handle
* @shm: Shared memory handle
*/
void tee_shm_put(struct tee_shm *shm)
{
struct tee_device *teedev = shm->ctx->teedev;
bool do_release = false;
mutex_lock(&teedev->mutex);
if (refcount_dec_and_test(&shm->refcount)) {
/*
* refcount has reached 0, we must now remove it from the
* IDR before releasing the mutex. This will guarantee that
* the refcount_inc() in tee_shm_get_from_id() never starts
* from 0.
*/
if (shm->flags & TEE_SHM_DMA_BUF)
idr_remove(&teedev->idr, shm->id);
do_release = true;
}
mutex_unlock(&teedev->mutex);
if (do_release)
tee_shm_release(teedev, shm);
}
EXPORT_SYMBOL_GPL(tee_shm_put);