On Wed, 2018-12-12 at 15:35 +0100, Thomas Hellstrom wrote:
> With the new validation code, a malicious user-space app could
> potentially submit command streams with enough buffer-object and
> resource
> references in them to have the resulting allocated validion nodes and
> relocations make the kernel run out of GFP_KERNEL memory.
>
> Protect from this by having the validation code reserve TTM graphics
> memory when allocating.
>
> Signed-off-by: Thomas Hellstrom <thellstrom@xxxxxxxxxx>
> ---
> v2: Removed leftover debug printouts
> ---
> drivers/gpu/drm/vmwgfx/vmwgfx_drv.c | 4 ++-
> drivers/gpu/drm/vmwgfx/vmwgfx_drv.h | 5 +++
> drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c | 2 ++
> drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c | 36
> +++++++++++++++++++++
> drivers/gpu/drm/vmwgfx/vmwgfx_validation.c | 18 ++++++++++-
> drivers/gpu/drm/vmwgfx/vmwgfx_validation.h | 37
> ++++++++++++++++++++++
> 6 files changed, 100 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> index 61a84b958d67..d7a2dfb8ee9b 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
> @@ -49,6 +49,8 @@
>
> #define VMWGFX_REPO "In Tree"
>
> +#define VMWGFX_VALIDATION_MEM_GRAN (16*PAGE_SIZE)
> +
>
> /**
> * Fully encoded drm commands. Might move to vmw_drm.h
> @@ -918,7 +920,7 @@ static int vmw_driver_load(struct drm_device
> *dev, unsigned long chipset)
> spin_unlock(&dev_priv->cap_lock);
> }
>
> -
> + vmw_validation_mem_init_ttm(dev_priv,
> VMWGFX_VALIDATION_MEM_GRAN);
> ret = vmw_kms_init(dev_priv);
> if (unlikely(ret != 0))
> goto out_no_kms;
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> index 59f614225bcd..aca974b14b55 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
> @@ -606,6 +606,9 @@ struct vmw_private {
>
> struct vmw_cmdbuf_man *cman;
> DECLARE_BITMAP(irqthread_pending, VMW_IRQTHREAD_MAX);
> +
> + /* Validation memory reservation */
> + struct vmw_validation_mem vvm;
> };
>
> static inline struct vmw_surface *vmw_res_to_srf(struct vmw_resource
> *res)
> @@ -846,6 +849,8 @@ extern int vmw_ttm_global_init(struct vmw_private
> *dev_priv);
> extern void vmw_ttm_global_release(struct vmw_private *dev_priv);
> extern int vmw_mmap(struct file *filp, struct vm_area_struct *vma);
>
> +extern void vmw_validation_mem_init_ttm(struct vmw_private
> *dev_priv,
> + size_t gran);
> /**
> * TTM buffer object driver - vmwgfx_ttm_buffer.c
> */
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> index 260650bb5560..f2d13a72c05d 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
> @@ -3835,6 +3835,8 @@ int vmw_execbuf_process(struct drm_file
> *file_priv,
> struct sync_file *sync_file = NULL;
> DECLARE_VAL_CONTEXT(val_ctx, &sw_context->res_ht, 1);
>
> + vmw_validation_set_val_mem(&val_ctx, &dev_priv->vvm);
> +
> if (flags & DRM_VMW_EXECBUF_FLAG_EXPORT_FENCE_FD) {
> out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
> if (out_fence_fd < 0) {
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> index 7b1e5a5cbd2c..f88247046721 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_glue.c
> @@ -96,3 +96,39 @@ void vmw_ttm_global_release(struct vmw_private
> *dev_priv)
> drm_global_item_unref(&dev_priv->bo_global_ref.ref);
> drm_global_item_unref(&dev_priv->mem_global_ref);
> }
> +
> +/* struct vmw_validation_mem callback */
> +static int vmw_vmt_reserve(struct vmw_validation_mem *m, size_t
> size)
> +{
> + static struct ttm_operation_ctx ctx = {.interruptible = false,
> + .no_wait_gpu = false};
> + struct vmw_private *dev_priv = container_of(m, struct
> vmw_private, vvm);
> +
> + return ttm_mem_global_alloc(vmw_mem_glob(dev_priv), size,
> &ctx);
> +}
> +
> +/* struct vmw_validation_mem callback */
> +static void vmw_vmt_unreserve(struct vmw_validation_mem *m, size_t
> size)
> +{
> + struct vmw_private *dev_priv = container_of(m, struct
> vmw_private, vvm);
> +
> + return ttm_mem_global_free(vmw_mem_glob(dev_priv), size);
> +}
> +
> +/**
> + * vmw_validation_mem_init_ttm - Interface the validation memory
> tracker
> + * to ttm.
> + * @dev_priv: Pointer to struct vmw_private. The reason we choose a
> vmw private
> + * rather than a struct vmw_validation_mem is to make sure
> assumption in the
> + * callbacks that struct vmw_private derives from struct
> vmw_validation_mem
> + * holds true.
> + * @gran: The recommended allocation granularity
> + */
> +void vmw_validation_mem_init_ttm(struct vmw_private *dev_priv,
> size_t gran)
> +{
> + struct vmw_validation_mem *vvm = &dev_priv->vvm;
> +
> + vvm->reserve_mem = vmw_vmt_reserve;
> + vvm->unreserve_mem = vmw_vmt_unreserve;
> + vvm->gran = gran;
> +}
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
> b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
> index 184025fa938e..1f83b90fd259 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.c
> @@ -104,11 +104,25 @@ void *vmw_validation_mem_alloc(struct
> vmw_validation_context *ctx,
> return NULL;
>
> if (ctx->mem_size_left < size) {
> - struct page *page = alloc_page(GFP_KERNEL |
> __GFP_ZERO);
> + struct page *page;
>
> + if (ctx->vm && ctx->vm_size_left < PAGE_SIZE) {
I quite didn't understand the logic here but ctx->vm_size_left is set
to GRAN size which is 16 * PAGE_SIZE so it will go inside this
condition for one time only. Is that what is intended here? Also I
guess that is why not resetting ctx->vm_size_left ?
Other than that looks good to me.
> + int ret = ctx->vm->reserve_mem(ctx->vm, ctx-
> >vm->gran);
> +
> + if (ret)
> + return NULL;
> +
> + ctx->vm_size_left += ctx->vm->gran;
> + ctx->total_mem += ctx->vm->gran;
> + }
> +
> + page = alloc_page(GFP_KERNEL | __GFP_ZERO);
> if (!page)
> return NULL;
>
> + if (ctx->vm)
> + ctx->vm_size_left -= PAGE_SIZE;
> +
> list_add_tail(&page->lru, &ctx->page_list);
> ctx->page_address = page_address(page);
> ctx->mem_size_left = PAGE_SIZE;
> @@ -138,6 +152,8 @@ static void vmw_validation_mem_free(struct
> vmw_validation_context *ctx)
> }
>
> ctx->mem_size_left = 0;
> + if (ctx->vm && ctx->total_mem)
> + ctx->vm->unreserve_mem(ctx->vm, ctx->total_mem);
> }
>
> /**
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.h
> b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.h
> index b57e3292c386..3b396fea40d7 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_validation.h
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_validation.h
> @@ -33,6 +33,21 @@
> #include <linux/ww_mutex.h>
> #include <drm/ttm/ttm_execbuf_util.h>
>
> +/**
> + * struct vmw_validation_mem - Custom interface to provide memory
> reservations
> + * for the validation code.
> + * @reserve_mem: Callback to reserve memory
> + * @unreserve_mem: Callback to unreserve memory
> + * @gran: Reservation granularity. Contains a hint how much memory
> should
> + * be reserved in each call to @reserve_mem(). A slow implementation
> may want
> + * reservation to be done in large batches.
> + */
> +struct vmw_validation_mem {
> + int (*reserve_mem)(struct vmw_validation_mem *m, size_t size);
> + void (*unreserve_mem)(struct vmw_validation_mem *m, size_t
> size);
> + size_t gran;
> +};
> +
> /**
> * struct vmw_validation_context - Per command submission validation
> context
> * @ht: Hash table used to find resource- or buffer object
> duplicates
> @@ -47,6 +62,10 @@
> * buffer objects
> * @mem_size_left: Free memory left in the last page in @page_list
> * @page_address: Kernel virtual address of the last page in
> @page_list
> + * @vm: A pointer to the memory reservation interface or NULL if no
> + * memory reservation is needed.
> + * @vm_size_left: Amount of reserved memory that so far has not been
> allocated.
> + * @total_mem: Amount of reserved memory.
> */
> struct vmw_validation_context {
> struct drm_open_hash *ht;
> @@ -59,6 +78,9 @@ struct vmw_validation_context {
> unsigned int merge_dups;
> unsigned int mem_size_left;
> u8 *page_address;
> + struct vmw_validation_mem *vm;
> + size_t vm_size_left;
> + size_t total_mem;
> };
>
> struct vmw_buffer_object;
> @@ -101,6 +123,21 @@ vmw_validation_has_bos(struct
> vmw_validation_context *ctx)
> return !list_empty(&ctx->bo_list);
> }
>
> +/**
> + * vmw_validation_set_val_mem - Register a validation mem object for
> + * validation memory reservation
> + * @ctx: The validation context
> + * @vm: Pointer to a struct vmw_validation_mem
> + *
> + * Must be set before the first attempt to allocate validation
> memory.
> + */
> +static inline void
> +vmw_validation_set_val_mem(struct vmw_validation_context *ctx,
> + struct vmw_validation_mem *vm)
> +{
> + ctx->vm = vm;
> +}
> +
> /**
> * vmw_validation_set_ht - Register a hash table for duplicate
> finding
> * @ctx: The validation context
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