linux/drivers/tee/tee_shm.c
Jens Wiklander 573ae4f13f tee: add overflow check in register_shm_helper()
With special lengths supplied by user space, register_shm_helper() has
an integer overflow when calculating the number of pages covered by a
supplied user space memory region.

This causes internal_get_user_pages_fast() a helper function of
pin_user_pages_fast() to do a NULL pointer dereference:

  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
  Modules linked in:
  CPU: 1 PID: 173 Comm: optee_example_a Not tainted 5.19.0 #11
  Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
  pc : internal_get_user_pages_fast+0x474/0xa80
  Call trace:
   internal_get_user_pages_fast+0x474/0xa80
   pin_user_pages_fast+0x24/0x4c
   register_shm_helper+0x194/0x330
   tee_shm_register_user_buf+0x78/0x120
   tee_ioctl+0xd0/0x11a0
   __arm64_sys_ioctl+0xa8/0xec
   invoke_syscall+0x48/0x114

Fix this by adding an an explicit call to access_ok() in
tee_shm_register_user_buf() to catch an invalid user space address
early.

Fixes: 033ddf12bc ("tee: add register user memory")
Cc: stable@vger.kernel.org
Reported-by: Nimish Mishra <neelam.nimish@gmail.com>
Reported-by: Anirban Chakraborty <ch.anirban00727@gmail.com>
Reported-by: Debdeep Mukhopadhyay <debdeep.mukhopadhyay@gmail.com>
Suggested-by: Jerome Forissier <jerome.forissier@linaro.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-08-18 09:20:27 -07:00

529 lines
13 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 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 int shm_get_kernel_pages(unsigned long start, size_t page_count,
struct page **pages)
{
size_t n;
int rc;
if (is_vmalloc_addr((void *)start)) {
struct page *page;
for (n = 0; n < page_count; n++) {
page = vmalloc_to_page((void *)(start + PAGE_SIZE * n));
if (!page)
return -ENOMEM;
get_page(page);
pages[n] = page;
}
rc = page_count;
} else {
struct kvec *kiov;
kiov = kcalloc(page_count, sizeof(*kiov), GFP_KERNEL);
if (!kiov)
return -ENOMEM;
for (n = 0; n < page_count; n++) {
kiov[n].iov_base = (void *)(start + n * PAGE_SIZE);
kiov[n].iov_len = PAGE_SIZE;
}
rc = get_kernel_pages(kiov, page_count, 0, pages);
kfree(kiov);
}
return rc;
}
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);
static struct tee_shm *
register_shm_helper(struct tee_context *ctx, unsigned long addr,
size_t length, u32 flags, int id)
{
struct tee_device *teedev = ctx->teedev;
struct tee_shm *shm;
unsigned long start;
size_t num_pages;
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(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_free_shm;
}
if (flags & TEE_SHM_USER_MAPPED)
rc = pin_user_pages_fast(start, num_pages, FOLL_WRITE,
shm->pages);
else
rc = shm_get_kernel_pages(start, num_pages, shm->pages);
if (rc > 0)
shm->num_pages = rc;
if (rc != num_pages) {
if (rc >= 0)
rc = -ENOMEM;
ret = ERR_PTR(rc);
goto err_put_shm_pages;
}
rc = teedev->desc->ops->shm_register(ctx, shm, shm->pages,
shm->num_pages, start);
if (rc) {
ret = ERR_PTR(rc);
goto err_put_shm_pages;
}
return shm;
err_put_shm_pages:
if (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);
err_free_shm:
kfree(shm);
err_ctx_put:
teedev_ctx_put(ctx);
err_dev_put:
tee_device_put(teedev);
return ret;
}
/**
* tee_shm_register_user_buf() - Register a userspace shared memory buffer
* @ctx: Context that registers the shared memory
* @addr: The userspace address of the shared buffer
* @length: Length of the shared buffer
*
* @returns a pointer to 'struct tee_shm'
*/
struct tee_shm *tee_shm_register_user_buf(struct tee_context *ctx,
unsigned long addr, size_t length)
{
u32 flags = TEE_SHM_USER_MAPPED | TEE_SHM_DYNAMIC;
struct tee_device *teedev = ctx->teedev;
struct tee_shm *shm;
void *ret;
int id;
if (!access_ok((void __user *)addr, length))
return ERR_PTR(-EFAULT);
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 = register_shm_helper(ctx, addr, length, 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_register_kernel_buf() - Register kernel memory to be shared with
* secure world
* @ctx: Context that registers the shared memory
* @addr: The buffer
* @length: Length of the buffer
*
* @returns a pointer to 'struct tee_shm'
*/
struct tee_shm *tee_shm_register_kernel_buf(struct tee_context *ctx,
void *addr, size_t length)
{
u32 flags = TEE_SHM_DYNAMIC;
return register_shm_helper(ctx, (unsigned long)addr, length, flags, -1);
}
EXPORT_SYMBOL_GPL(tee_shm_register_kernel_buf);
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->id < 0)
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_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->kaddr)
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->id >= 0)
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);