Re: [EXT] Re: [PATCH 1/3] dma-buf: heaps: add Linaro secure dmabuf heap support

[Olivier Masse <olivier.masse@nxp.com>]

Hi Brian,

On ven., 2022-08-05 at 16:41 +0100, Brian Starkey wrote:
> Caution: EXT Email
> 
> Hi Olivier,
> 
> Thanks, I think this is looking much better.
> 
> I'd like to know how others feel about landing this heap; there's
> been
> push-back in the past about heaps in device-tree and discussions
> around how "custom" heaps should be treated (though IMO this is quite
> a generic one).
> 
> On Fri, Aug 05, 2022 at 03:53:28PM +0200, Olivier Masse wrote:
> > add Linaro secure heap bindings: linaro,secure-heap
> > use genalloc to allocate/free buffer from buffer pool.
> > buffer pool info is from dts.
> > use sg_table instore the allocated memory info, the length of
> > sg_table is 1.
> > implement secure_heap_buf_ops to implement buffer share in
> > difference device:
> > 1. Userspace passes this fd to all drivers it wants this buffer
> > to share with: First the filedescriptor is converted to a &dma_buf
> > using
> > dma_buf_get(). Then the buffer is attached to the device using
> > dma_buf_attach().
> > 2. Once the buffer is attached to all devices userspace can
> > initiate DMA
> > access to the shared buffer. In the kernel this is done by calling
> > dma_buf_map_attachment()
> > 3. get sg_table with dma_buf_map_attachment in difference device.
> > 
> 
> I think this commit message could use a little rework. A few
> thoughts:
> 
> * The bindings are in a separate commit, so seems strange to mention
>   here.

what about:
"add Linaro secure heap compatible reserved memory: linaro,secure-heap"

> * "buffer pool info is from dts" --> I think you should mention that
>   this uses a reserved-memory region.
ok

> * sg_table nents and genalloc seem like low-level implementation
>   details, so probably not needed in the commit message
> * The usage steps 1, 2, 3 aren't specific to this heap - that's how
>   all dma-buf sharing works.
ok, let's cleanup and removed this.

> 
> > Signed-off-by: Olivier Masse <olivier.masse@nxp.com>
> > ---
> >  drivers/dma-buf/heaps/Kconfig       |   9 +
> >  drivers/dma-buf/heaps/Makefile      |   1 +
> >  drivers/dma-buf/heaps/secure_heap.c | 357
> > ++++++++++++++++++++++++++++
> >  3 files changed, 367 insertions(+)
> >  create mode 100644 drivers/dma-buf/heaps/secure_heap.c
> > 
> > diff --git a/drivers/dma-buf/heaps/Kconfig b/drivers/dma-
> > buf/heaps/Kconfig
> > index 3782eeeb91c0..c9070c728b9a 100644
> > --- a/drivers/dma-buf/heaps/Kconfig
> > +++ b/drivers/dma-buf/heaps/Kconfig
> > @@ -20,3 +20,12 @@ config DMABUF_HEAPS_DSP
> >            Choose this option to enable the dsp dmabuf heap. The
> > dsp heap
> >            is allocated by gen allocater. it's allocated according
> > the dts.
> >            If in doubt, say Y.
> > +
> > +config DMABUF_HEAPS_SECURE
> > +     tristate "DMA-BUF Secure Heap"
> > +     depends on DMABUF_HEAPS
> > +     help
> > +       Choose this option to enable the secure dmabuf heap. The
> > secure heap
> > +       pools are defined according to the DT. Heaps are allocated
> > +       in the pools using gen allocater.
> > +       If in doubt, say Y.
> > diff --git a/drivers/dma-buf/heaps/Makefile b/drivers/dma-
> > buf/heaps/Makefile
> > index 29733f84c354..863ef10056a3 100644
> > --- a/drivers/dma-buf/heaps/Makefile
> > +++ b/drivers/dma-buf/heaps/Makefile
> > @@ -2,3 +2,4 @@
> >  obj-$(CONFIG_DMABUF_HEAPS_SYSTEM)    += system_heap.o
> >  obj-$(CONFIG_DMABUF_HEAPS_CMA)               += cma_heap.o
> >  obj-$(CONFIG_DMABUF_HEAPS_DSP)          += dsp_heap.o
> > +obj-$(CONFIG_DMABUF_HEAPS_SECURE)    += secure_heap.o
> > diff --git a/drivers/dma-buf/heaps/secure_heap.c b/drivers/dma-
> > buf/heaps/secure_heap.c
> > new file mode 100644
> > index 000000000000..25b3629613f3
> > --- /dev/null
> > +++ b/drivers/dma-buf/heaps/secure_heap.c
> > @@ -0,0 +1,357 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * DMABUF secure heap exporter
> > + *
> > + * Copyright 2021 NXP.
> 
> It's 2022 :-)
> 
> > + */
> > +
> > +#include <linux/dma-buf.h>
> > +#include <linux/dma-heap.h>
> > +#include <linux/dma-mapping.h>
> > +#include <linux/err.h>
> > +#include <linux/genalloc.h>
> > +#include <linux/highmem.h>
> > +#include <linux/mm.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_fdt.h>
> > +#include <linux/of_reserved_mem.h>
> > +#include <linux/scatterlist.h>
> > +#include <linux/slab.h>
> > +#include <linux/vmalloc.h>
> > +
> > +#define MAX_SECURE_HEAP 2
> > +#define MAX_HEAP_NAME_LEN 32
> > +
> > +struct secure_heap_buffer {
> > +     struct dma_heap *heap;
> > +     struct list_head attachments;
> > +     struct mutex lock;
> > +     unsigned long len;
> > +     struct sg_table sg_table;
> > +     int vmap_cnt;
> > +     void *vaddr;
> > +};
> > +
> > +struct secure_heap_attachment {
> > +     struct device *dev;
> > +     struct sg_table *table;
> > +     struct list_head list;
> > +};
> > +
> > +struct secure_heap_info {
> > +     struct gen_pool *pool;
> > +};
> > +
> > +struct rmem_secure {
> > +     phys_addr_t base;
> > +     phys_addr_t size;
> > +
> > +     char name[MAX_HEAP_NAME_LEN];
> > +};
> > +
> > +static struct rmem_secure secure_data[MAX_SECURE_HEAP] = {0};
> > +static unsigned int secure_data_count;
> > +
> > +static struct sg_table *dup_sg_table(struct sg_table *table)
> > +{
> > +     struct sg_table *new_table;
> > +     int ret, i;
> > +     struct scatterlist *sg, *new_sg;
> > +
> > +     new_table = kzalloc(sizeof(*new_table), GFP_KERNEL);
> > +     if (!new_table)
> > +             return ERR_PTR(-ENOMEM);
> > +
> > +     ret = sg_alloc_table(new_table, table->orig_nents,
> > GFP_KERNEL);
> > +     if (ret) {
> > +             kfree(new_table);
> > +             return ERR_PTR(-ENOMEM);
> > +     }
> > +
> > +     new_sg = new_table->sgl;
> > +     for_each_sgtable_sg(table, sg, i) {
> > +             sg_set_page(new_sg, sg_page(sg), sg->length, sg-
> > >offset);
> > +             new_sg->dma_address = sg->dma_address;
> > +#ifdef CONFIG_NEED_SG_DMA_LENGTH
> > +             new_sg->dma_length = sg->dma_length;
> > +#endif
> > +             new_sg = sg_next(new_sg);
> > +     }
> > +
> > +     return new_table;
> > +}
> > +
> > +static int secure_heap_attach(struct dma_buf *dmabuf,
> > +                           struct dma_buf_attachment *attachment)
> > +{
> > +     struct secure_heap_buffer *buffer = dmabuf->priv;
> > +     struct secure_heap_attachment *a;
> > +     struct sg_table *table;
> > +
> > +     a = kzalloc(sizeof(*a), GFP_KERNEL);
> > +     if (!a)
> > +             return -ENOMEM;
> > +
> > +     table = dup_sg_table(&buffer->sg_table);
> > +     if (IS_ERR(table)) {
> > +             kfree(a);
> > +             return -ENOMEM;
> 
> nit: You could return PTR_ERR(table), in case dup_sg_table starts
> returning other errors.
> 
> > +     }
> > +
> > +     a->table = table;
> > +     a->dev = attachment->dev;
> > +     INIT_LIST_HEAD(&a->list);
> > +     attachment->priv = a;
> > +
> > +     mutex_lock(&buffer->lock);
> > +     list_add(&a->list, &buffer->attachments);
> > +     mutex_unlock(&buffer->lock);
> > +
> > +     return 0;
> > +}
> > +
> > +static void secure_heap_detach(struct dma_buf *dmabuf,
> > +                            struct dma_buf_attachment *attachment)
> > +{
> > +     struct secure_heap_buffer *buffer = dmabuf->priv;
> > +     struct secure_heap_attachment *a = attachment->priv;
> > +
> > +     mutex_lock(&buffer->lock);
> > +     list_del(&a->list);
> > +     mutex_unlock(&buffer->lock);
> > +
> > +     sg_free_table(a->table);
> > +     kfree(a->table);
> > +     kfree(a);
> > +}
> > +
> > +static struct sg_table *secure_heap_map_dma_buf(struct
> > dma_buf_attachment *attachment,
> > +                                             enum
> > dma_data_direction direction)
> > +{
> > +     struct secure_heap_attachment *a = attachment->priv;
> > +
> > +     return a->table;
> 
> I think you still need to implement mapping and unmapping using the
> DMA APIs. For example devices might be behind IOMMUs and the buffer
> will need mapping into the IOMMU.

Devices that will need access to the buffer must be in secure.
The tee driver will only need the scatter-list table to get dma address
and len. Mapping will be done in the TEE.
Please find tee_shm_register_fd in the following commit
https://github.com/linaro-swg/linux/commit/41e21e5c405530590dc2dd10b2a8dbe64589840f

This patch need to be up-streamed as well.


> 
> > +}
> > +
> > +static void secure_heap_unmap_dma_buf(struct dma_buf_attachment
> > *attachment,
> > +                                   struct sg_table *table,
> > +                                   enum dma_data_direction
> > direction)
> > +{
> > +}
> > +
> > +static void secure_heap_dma_buf_release(struct dma_buf *dmabuf)
> > +{
> > +     struct secure_heap_buffer *buffer = dmabuf->priv;
> > +     struct secure_heap_info *info;
> > +     struct sg_table *table;
> > +     struct scatterlist *sg;
> > +     int i;
> > +
> > +     info = dma_heap_get_drvdata(buffer->heap);
> > +
> > +     table = &buffer->sg_table;
> > +     for_each_sg(table->sgl, sg, table->nents, i)
> > +             gen_pool_free(info->pool, sg_dma_address(sg),
> > sg_dma_len(sg));
> > +
> > +     sg_free_table(table);
> > +     kfree(buffer);
> > +}
> > +
> > +static const struct dma_buf_ops secure_heap_buf_ops = {
> > +     .attach = secure_heap_attach,
> > +     .detach = secure_heap_detach,
> > +     .map_dma_buf = secure_heap_map_dma_buf,
> > +     .unmap_dma_buf = secure_heap_unmap_dma_buf,
> > +     .release = secure_heap_dma_buf_release,
> > +};
> > +
> > +static struct dma_buf *secure_heap_allocate(struct dma_heap *heap,
> > +                                         unsigned long len,
> > +                                         unsigned long fd_flags,
> > +                                         unsigned long heap_flags)
> > +{
> > +     struct secure_heap_buffer *buffer;
> > +     struct secure_heap_info *info = dma_heap_get_drvdata(heap);
> > +     DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
> > +     unsigned long size = roundup(len, PAGE_SIZE);
> > +     struct dma_buf *dmabuf;
> > +     struct sg_table *table;
> > +     int ret = -ENOMEM;
> > +     unsigned long phy_addr;
> > +
> > +     buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
> > +     if (!buffer)
> > +             return ERR_PTR(-ENOMEM);
> > +
> > +     INIT_LIST_HEAD(&buffer->attachments);
> > +     mutex_init(&buffer->lock);
> > +     buffer->heap = heap;
> > +     buffer->len = size;
> > +
> > +     phy_addr = gen_pool_alloc(info->pool, size);
> > +     if (!phy_addr)
> > +             goto free_buffer;
> > +
> > +     table = &buffer->sg_table;
> > +     if (sg_alloc_table(table, 1, GFP_KERNEL))
> > +             goto free_pool;
> > +
> > +     sg_set_page(table->sgl, phys_to_page(phy_addr), size, 0);
> > +     sg_dma_address(table->sgl) = phy_addr;
> > +     sg_dma_len(table->sgl) = size;
> > +
> > +     /* create the dmabuf */
> > +     exp_info.exp_name = dma_heap_get_name(heap);
> > +     exp_info.ops = &secure_heap_buf_ops;
> > +     exp_info.size = buffer->len;
> > +     exp_info.flags = fd_flags;
> > +     exp_info.priv = buffer;
> > +     dmabuf = dma_buf_export(&exp_info);
> > +     if (IS_ERR(dmabuf)) {
> > +             ret = PTR_ERR(dmabuf);
> > +             goto free_pages;
> > +     }
> > +
> > +     return dmabuf;
> > +
> > +free_pages:
> 
> Should maybe be called free_table:

right
> 
> > +     sg_free_table(table);
> > +
> > +free_pool:
> > +     gen_pool_free(info->pool, phy_addr, size);
> > +
> > +free_buffer:
> > +     mutex_destroy(&buffer->lock);
> > +     kfree(buffer);
> > +
> > +     return ERR_PTR(ret);
> > +}
> > +
> > +static const struct dma_heap_ops secure_heap_ops = {
> > +     .allocate = secure_heap_allocate,
> > +};
> > +
> > +static int secure_heap_add(struct rmem_secure *rmem)
> > +{
> > +     struct dma_heap *secure_heap;
> > +     struct dma_heap_export_info exp_info;
> > +     struct secure_heap_info *info = NULL;
> > +     struct gen_pool *pool = NULL;
> > +     int ret = -EINVAL;
> > +
> > +     if (rmem->base == 0 || rmem->size == 0) {
> > +             pr_err("secure_data base or size is not correct\n");
> > +             goto error;
> > +     }
> > +
> > +     info = kzalloc(sizeof(*info), GFP_KERNEL);
> > +     if (!info) {
> > +             pr_err("dmabuf info allocation failed\n");
> > +             ret = -ENOMEM;
> > +             goto error;
> > +     }
> > +
> > +     pool = gen_pool_create(PAGE_SHIFT, -1);
> > +     if (!pool) {
> > +             pr_err("can't create gen pool\n");
> > +             ret = -ENOMEM;
> > +             goto error;
> > +     }
> > +
> > +     if (gen_pool_add(pool, rmem->base, rmem->size, -1) < 0) {
> > +             pr_err("failed to add memory into pool\n");
> > +             ret = -ENOMEM;
> > +             goto error;
> > +     }
> > +
> > +     info->pool = pool;
> > +
> > +     exp_info.name = rmem->name;
> > +     exp_info.ops = &secure_heap_ops;
> > +     exp_info.priv = info;
> > +
> > +     secure_heap = dma_heap_add(&exp_info);
> > +     if (IS_ERR(secure_heap)) {
> > +             pr_err("dmabuf secure heap allocation failed\n");
> > +             ret = PTR_ERR(secure_heap);
> > +             goto error;
> > +     }
> > +
> > +     return 0;
> > +
> > +error:
> > +     kfree(info);
> > +     if (pool)
> > +             gen_pool_destroy(pool);
> 
> nit: I think your order should be reversed here, to match the
> opposite
> order of allocation.

agree
> 
> > +
> > +     return ret;
> > +}
> > +
> > +static int secure_heap_create(void)
> > +{
> > +     unsigned int i;
> > +     int ret;
> > +
> > +     for (i = 0; i < secure_data_count; i++) {
> > +             ret = secure_heap_add(&secure_data[i]);
> > +             if (ret)
> > +                     return ret;
> > +     }
> > +     return 0;
> > +}
> > +
> > +static int rmem_secure_heap_device_init(struct reserved_mem *rmem,
> > +                                      struct device *dev)
> > +{
> > +     dev_set_drvdata(dev, rmem);
> > +     return 0;
> > +}
> > +
> > +static void rmem_secure_heap_device_release(struct reserved_mem
> > *rmem,
> > +                                      struct device *dev)
> > +{
> > +     dev_set_drvdata(dev, NULL);
> > +}
> > +
> > +static const struct reserved_mem_ops rmem_dma_ops = {
> > +     .device_init    = rmem_secure_heap_device_init,
> > +     .device_release = rmem_secure_heap_device_release,
> > +};
> 
> What are these reserved_mem_ops for? Setting the drvdata for a random
> device seems like it could cause lots of problems.
> 
> Is there a requirement to support assigning this SDP reserved-memory
> region to a specific device? If not, I think you can just drop this.
> Otherwise, I think you need some other mechanism to do the
> association.

indeed, can be removed as driver private data is set at heap creation
and should not be modified.

> 
> > +
> > +static int __init rmem_secure_heap_setup(struct reserved_mem
> > *rmem)
> > +{
> > +     if (secure_data_count < MAX_SECURE_HEAP) {
> > +             int name_len = 0;
> > +             const char *s = rmem->name;
> > +
> > +             secure_data[secure_data_count].base = rmem->base;
> > +             secure_data[secure_data_count].size = rmem->size;
> > +
> > +             while (name_len < MAX_HEAP_NAME_LEN) {
> > +                     if ((*s == '@') || (*s == '\0'))
> > +                             break;
> > +                     name_len++;
> > +                     s++;
> > +             }
> > +             if (name_len == MAX_HEAP_NAME_LEN)
> > +                     name_len--;
> > +
> > +             strncpy(secure_data[secure_data_count].name, rmem-
> > >name, name_len);
> 
> I think it would be good to explicitly do:
> 
>   secure_data[secure_data_count].name[name_len] = '\0'

ok
> 
> I know it's zero-initialised, but that's done on a line far away, so
> may be best to be defensive.
> 
> > +
> > +             rmem->ops = &rmem_dma_ops;
> > +             pr_info("Reserved memory: DMA buf secure pool %s at
> > %pa, size %ld MiB\n",
> > +                     secure_data[secure_data_count].name,
> > +                     &rmem->base, (unsigned long)rmem->size /
> > SZ_1M);
> 
> nit: What if rmem->size < SZ_1M, or not 1M-aligned
> 
> > +
> > +             secure_data_count++;
> > +             return 0;
> > +     }
> > +     WARN_ONCE(1, "Cannot handle more than %u secure heaps\n",
> > MAX_SECURE_HEAP);
> > +     return -EINVAL;
> > +}
> > +
> > +RESERVEDMEM_OF_DECLARE(secure_heap, "linaro,secure-heap",
> > rmem_secure_heap_setup);
> 
> Is there anything linaro-specific about this? Could it be
> linux,secure-heap?

for now, it's specific to Linaro OPTEE OS.
but in a more generic way, it could be 
linux,unmapped-heap ?

> 
> Thanks,
> -Brian
> 
> > +
> > +module_init(secure_heap_create);
> > +MODULE_LICENSE("GPL v2");
> > --
> > 2.25.0
> >