Reviewed-by: Deepak Rawat <drawat@xxxxxxxxxx>
On Wed, 2018-12-12 at 10:38 -0800, Thomas Hellstrom wrote:
> Hi, Deepak,
>
> On Wed, 2018-12-12 at 10:00 -0800, Deepak Singh Rawat wrote:
> > 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 ?
>
>
> ctx->vm_size_left is decreased with PAGE_SIZE after allocating a
> page,
> which means we do a new reservation each 16 pages, but typically that
> much memory is very seldom used, so in essence we will do a memory
> reservation once per command buffer. Although it's correct we should
> clear ctx->vm_size_left when we unreserve.
>
> /Thomas
Yes, got it. Overlooked the decrease as error handling and didn't
realize the free function is to free all memory.
>
>
> >
> > 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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