On Thu, May 02, 2019 at 06:52:56PM +0530, Ramalingam C wrote:

On every hdcp revocation check request SRM is read from fw file /lib/firmware/display_hdcp_srm.bin

SRM table is parsed and stored at drm_hdcp.c, with functions exported for the services for revocation check from drivers (which implements the HDCP authentication)

This patch handles the HDCP1.4 and 2.2 versions of SRM table.

v2: moved the uAPI to request_firmware_direct() [Daniel] v3: kdoc added. [Daniel] srm_header unified and bit field definitions are removed. [Daniel] locking improved. [Daniel] vrl length violation is fixed. [Daniel]

Signed-off-by: Ramalingam C ramalingam.c@intel.com Suggested-by: Daniel Vetter daniel@ffwll.ch

Found a few small details to polish, but looks good to me. With the details addressed:

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

We also still need an ack on the firmware blob approach from Matt Roper or someone else at iotg I think.

Cheers, Daniel

---

Documentation/gpu/drm-kms-helpers.rst | 6 + drivers/gpu/drm/Makefile | 2 +- drivers/gpu/drm/drm_hdcp.c | 342 ++++++++++++++++++++++++++ drivers/gpu/drm/drm_internal.h | 4 + drivers/gpu/drm/drm_sysfs.c | 2 + include/drm/drm_hdcp.h | 24 ++ 6 files changed, 379 insertions(+), 1 deletion(-) create mode 100644 drivers/gpu/drm/drm_hdcp.c

diff --git a/Documentation/gpu/drm-kms-helpers.rst b/Documentation/gpu/drm-kms-helpers.rst index 14102ae035dc..0fe726a6ee67 100644 --- a/Documentation/gpu/drm-kms-helpers.rst +++ b/Documentation/gpu/drm-kms-helpers.rst @@ -181,6 +181,12 @@ Panel Helper Reference .. kernel-doc:: drivers/gpu/drm/drm_panel_orientation_quirks.c :export:

+HDCP Helper Functions Reference +===============================

+.. kernel-doc:: drivers/gpu/drm/drm_hdcp.c

• :export:

Display Port Helper Functions Reference

diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index 72f5036d9bfa..dd02e9dec810 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -17,7 +17,7 @@ drm-y := drm_auth.o drm_cache.o \ drm_plane.o drm_color_mgmt.o drm_print.o \ drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \ drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \

• drm_atomic_uapi.o
  

• drm_atomic_uapi.o drm_hdcp.o
  
  

drm-$(CONFIG_DRM_LEGACY) += drm_legacy_misc.o drm_bufs.o drm_context.o drm_dma.o drm_scatter.o drm_lock.o drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o diff --git a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c new file mode 100644 index 000000000000..dc0e13409221 --- /dev/null +++ b/drivers/gpu/drm/drm_hdcp.c @@ -0,0 +1,342 @@ +// SPDX-License-Identifier: GPL-2.0 +/*

• • Copyright (C) 2019 Intel Corporation.
• • Authors:
• • Ramalingam C ramalingam.c@intel.com
• */

+#include <linux/device.h> +#include <linux/err.h> +#include <linux/gfp.h> +#include <linux/export.h> +#include <linux/slab.h> +#include <linux/firmware.h>

+#include <drm/drm_hdcp.h> +#include <drm/drm_sysfs.h> +#include <drm/drm_print.h> +#include <drm/drm_device.h>

+struct hdcp_srm {

• u8 *srm_buf;

Allocated, but seems to not be used.

• size_t received_srm_sz;

Seems to be unused. Seems to both be leftovers from the sysfs interface.

• u32 revoked_ksv_cnt;
• u8 *revoked_ksv_list;
• /* Mutex to protect above struct member */
• struct mutex mutex;

+} *srm_data;

+static inline void drm_hdcp_print_ksv(const u8 *ksv) +{

• DRM_DEBUG("\t%#02x, %#02x, %#02x, %#02x, %#02x\n",

•   ksv[0], ksv[1], ksv[2], ksv[3], ksv[4]);
  

+}

+static u32 drm_hdcp_get_revoked_ksv_count(const u8 *buf, u32 vrls_length) +{

• u32 parsed_bytes = 0, ksv_count = 0, vrl_ksv_cnt, vrl_sz;
• while (parsed_bytes < vrls_length) {

• vrl_ksv_cnt = *buf;
  

• ksv_count += vrl_ksv_cnt;
  

• vrl_sz = (vrl_ksv_cnt * DRM_HDCP_KSV_LEN) + 1;
  

• buf += vrl_sz;
  

• parsed_bytes += vrl_sz;
  

• }
• /*

• * When vrls are not valid, ksvs are not considered.
  

• * Hence SRM will be discarded.
  

• */
  

• if (parsed_bytes != vrls_length)

• ksv_count = 0;
  

• return ksv_count;

+}

+static u32 drm_hdcp_get_revoked_ksvs(const u8 *buf, u8 *revoked_ksv_list,

• 		     u32 vrls_length)
  

+{

• u32 parsed_bytes = 0, ksv_count = 0;
• u32 vrl_ksv_cnt, vrl_ksv_sz, vrl_idx = 0;
• do {

• vrl_ksv_cnt = *buf;
  

• vrl_ksv_sz = vrl_ksv_cnt * DRM_HDCP_KSV_LEN;
  

• buf++;
  

• DRM_DEBUG("vrl: %d, Revoked KSVs: %d\n", vrl_idx++,
  

• 	  vrl_ksv_cnt);
  

• memcpy(revoked_ksv_list, buf, vrl_ksv_sz);
  

• ksv_count += vrl_ksv_cnt;
  

• revoked_ksv_list += vrl_ksv_sz;
  

• buf += vrl_ksv_sz;
  

• parsed_bytes += (vrl_ksv_sz + 1);
  

• } while (parsed_bytes < vrls_length);
• return ksv_count;

+}

+static inline u32 get_vrl_length(const u8 *buf) +{

• return (u32)(buf[0] << 16 | buf[1] << 8 | buf[2]);

This is the same conversion as drm_hdcp2_seq_num_to_u32. Maybe rename that to drm_hdcp_be24_bytes_to_cpu and use that instead of what you have hare. Plus rename the other function to drm_hdcp_u32_to_b24_bytes for consistency. Probably best to do that in a small prep patch.

+}

+static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count) +{

• struct hdcp_srm_header *header;
• u32 vrl_length, ksv_count;
• if (count < (sizeof(struct hdcp_srm_header) +

•    DRM_HDCP_1_4_VRL_LENGTH_SIZE + DRM_HDCP_1_4_DCP_SIG_SIZE)) {
  

• DRM_ERROR("Invalid blob length\n");
  

• return -EINVAL;
  

• }
• header = (struct hdcp_srm_header *)buf;
• DRM_DEBUG("SRM ID: 0x%x, SRM Ver: 0x%x, SRM Gen No: 0x%x\n",

•   header->srm_id,
  

•   __swab16(header->srm_version), header->srm_gen_no);
  

s/__swab16/be16_to_cpu/ everywhere. Otherwise it'll stop working on big endian cpus. Yes won't matter, but better correct, it's also better self-documenting code.

• WARN_ON(header->reserved);
• buf = buf + sizeof(*header);
• vrl_length = get_vrl_length(buf);
• if (count < (sizeof(struct hdcp_srm_header) + vrl_length) ||

•    vrl_length < (DRM_HDCP_1_4_VRL_LENGTH_SIZE +
  

• 	  DRM_HDCP_1_4_DCP_SIG_SIZE)) {
  

• DRM_ERROR("Invalid blob length or vrl length\n");
  

• return -EINVAL;
  

• }
• /* Length of the all vrls combined */
• vrl_length -= (DRM_HDCP_1_4_VRL_LENGTH_SIZE +

•        DRM_HDCP_1_4_DCP_SIG_SIZE);
  

• if (!vrl_length) {

• DRM_ERROR("No vrl found\n");
  

• return -EINVAL;
  

• }
• buf += DRM_HDCP_1_4_VRL_LENGTH_SIZE;
• ksv_count = drm_hdcp_get_revoked_ksv_count(buf, vrl_length);
• if (!ksv_count) {

• DRM_DEBUG("Revoked KSV count is 0\n");
  

• return count;
  

• }
• kfree(srm_data->revoked_ksv_list);
• srm_data->revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN,

• 			     GFP_KERNEL);
  

• if (!srm_data->revoked_ksv_list) {

• DRM_ERROR("Out of Memory\n");
  

• return -ENOMEM;
  

• }
• if (drm_hdcp_get_revoked_ksvs(buf, srm_data->revoked_ksv_list,

• 		      vrl_length) != ksv_count) {
  

• srm_data->revoked_ksv_cnt = 0;
  

• kfree(srm_data->revoked_ksv_list);
  

• return -EINVAL;
  

• }
• srm_data->revoked_ksv_cnt = ksv_count;
• return count;

+}

+static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count) +{

• struct hdcp_srm_header *header;
• u32 vrl_length, ksv_count, ksv_sz;
• if (count < (sizeof(struct hdcp_srm_header) +

•    DRM_HDCP_2_VRL_LENGTH_SIZE + DRM_HDCP_2_DCP_SIG_SIZE)) {
  

• DRM_ERROR("Invalid blob length\n");
  

• return -EINVAL;
  

• }
• header = (struct hdcp_srm_header *)buf;
• DRM_DEBUG("SRM ID: 0x%x, SRM Ver: 0x%x, SRM Gen No: 0x%x\n",

•   header->srm_id & DRM_HDCP_SRM_ID_MASK,
  

•   __swab16(header->srm_version), header->srm_gen_no);
  

• if (header->reserved)

• return -EINVAL;
  

• buf = buf + sizeof(*header);
• vrl_length = get_vrl_length(buf);
• if (count < (sizeof(struct hdcp_srm_header) + vrl_length) ||

•    vrl_length < (DRM_HDCP_2_VRL_LENGTH_SIZE +
  

•    DRM_HDCP_2_DCP_SIG_SIZE)) {
  

• DRM_ERROR("Invalid blob length or vrl length\n");
  

• return -EINVAL;
  

• }
• /* Length of the all vrls combined */
• vrl_length -= (DRM_HDCP_2_VRL_LENGTH_SIZE +

•        DRM_HDCP_2_DCP_SIG_SIZE);
  

• if (!vrl_length) {

• DRM_ERROR("No vrl found\n");
  

• return -EINVAL;
  

• }
• buf += DRM_HDCP_2_VRL_LENGTH_SIZE;
• ksv_count = (*buf << 2) | DRM_HDCP_2_KSV_COUNT_2_LSBITS(*(buf + 1));
• if (!ksv_count) {

• DRM_DEBUG("Revoked KSV count is 0\n");
  

• return count;
  

• }
• kfree(srm_data->revoked_ksv_list);
• srm_data->revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN,

• 			     GFP_KERNEL);
  

• if (!srm_data->revoked_ksv_list) {

• DRM_ERROR("Out of Memory\n");
  

• return -ENOMEM;
  

• }
• ksv_sz = ksv_count * DRM_HDCP_KSV_LEN;
• buf += DRM_HDCP_2_NO_OF_DEV_PLUS_RESERVED_SZ;
• DRM_DEBUG("Revoked KSVs: %d\n", ksv_count);
• memcpy(srm_data->revoked_ksv_list, buf, ksv_sz);
• srm_data->revoked_ksv_cnt = ksv_count;
• return count;

+}

+static inline bool is_srm_version_hdcp1(const u8 *buf) +{

• return *buf == (u8)(DRM_HDCP_1_4_SRM_ID << 4);

+}

+static inline bool is_srm_version_hdcp2(const u8 *buf) +{

• return *buf == (u8)(DRM_HDCP_2_SRM_ID << 4 | DRM_HDCP_2_INDICATOR);

+}

+static ssize_t drm_hdcp_srm_update(const u8 *buf, size_t count) +{

• if (is_srm_version_hdcp1(buf))

• return (ssize_t)drm_hdcp_parse_hdcp1_srm(buf, count);
  

• else if (is_srm_version_hdcp2(buf))

• return (ssize_t)drm_hdcp_parse_hdcp2_srm(buf, count);
  

• return (ssize_t)-EINVAL;

You wire return values through but then throw them away. Plus there's a confusion between int and ssize_t. Since you have DRM_DEBUG everywhere already and we don't care about any parsing errors anyyway I think best to throw the return values away and use void for all these functions.

+}

+void drm_hdcp_request_srm(struct drm_device *drm_dev) +{

• char fw_name[36] = "display_hdcp_srm.bin";
• const struct firmware *fw;
• int ret;
• ret = request_firmware_direct(&fw, (const char *)fw_name,

• 		      drm_dev->dev);
  

• if (ret < 0)

• goto exit;
  

• if (fw->size && fw->data)

• drm_hdcp_srm_update(fw->data, fw->size);
  

+exit:

• release_firmware(fw);

+}

+/**

• • drm_hdcp_check_ksvs_revoked - Check the revoked status of the IDs
• • @drm_dev: drm_device for which HDCP revocation check is requested
• • @ksvs: List of KSVs (HDCP receiver IDs)
• • @ksv_count: KSV count passed in through @ksvs
• • This function reads the HDCP System renewability Message(SRM Table)
• • from userspace as a firmware and parses it for the revoked HDCP
• • KSVs(Receiver IDs) detected by DCP LLC. Once the revoked KSVs are known,
• • revoked state of the KSVs in the list passed in by display drivers are
• • decided and response is sent.
• • SRM should be presented in the name of "display_hdcp_srm.bin".
• • Returns:
• • TRUE on any of the KSV is revoked, else FALSE.
• */

+bool drm_hdcp_check_ksvs_revoked(struct drm_device *drm_dev, u8 *ksvs,

• 		 u32 ksv_count)
  

+{

• u32 rev_ksv_cnt, cnt, i, j;
• u8 *rev_ksv_list;
• if (!srm_data)

• return false;
  

• mutex_lock(&srm_data->mutex);
• drm_hdcp_request_srm(drm_dev);
• rev_ksv_cnt = srm_data->revoked_ksv_cnt;
• rev_ksv_list = srm_data->revoked_ksv_list;
• /* If the Revoked ksv list is empty */
• if (!rev_ksv_cnt || !rev_ksv_list) {

• mutex_unlock(&srm_data->mutex);
  

• return false;
  

• }
• for (cnt = 0; cnt < ksv_count; cnt++) {

• rev_ksv_list = srm_data->revoked_ksv_list;
  

• for (i = 0; i < rev_ksv_cnt; i++) {
  

• 	for (j = 0; j < DRM_HDCP_KSV_LEN; j++)
  

• 		if (ksvs[j] != rev_ksv_list[j]) {
  

• 			break;
  

• 		} else if (j == (DRM_HDCP_KSV_LEN - 1)) {
  

• 			DRM_DEBUG("Revoked KSV is ");
  

• 			drm_hdcp_print_ksv(ksvs);
  

• 			mutex_unlock(&srm_data->mutex);
  

• 			return true;
  

• 		}
  

• 	/* Move the offset to next KSV in the revoked list */
  

• 	rev_ksv_list += DRM_HDCP_KSV_LEN;
  

• }
  

• /* Iterate to next ksv_offset */
  

• ksvs += DRM_HDCP_KSV_LEN;
  

• }
• mutex_unlock(&srm_data->mutex);
• return false;

+} +EXPORT_SYMBOL_GPL(drm_hdcp_check_ksvs_revoked);

+int drm_setup_hdcp_srm(struct class *drm_class) +{

• srm_data = kzalloc(sizeof(*srm_data), GFP_KERNEL);
• if (!srm_data)

• return -ENOMEM;
  

• srm_data->srm_buf = kcalloc(DRM_HDCP_SRM_GEN1_MAX_BYTES,

• 		    sizeof(u8), GFP_KERNEL);
  

• if (!srm_data->srm_buf) {

• kfree(srm_data);
  

• return -ENOMEM;
  

• }
• mutex_init(&srm_data->mutex);
• return 0;

+}

+void drm_teardown_hdcp_srm(struct class *drm_class) +{

• if (srm_data) {

• kfree(srm_data->srm_buf);
  

• kfree(srm_data->revoked_ksv_list);
  

• kfree(srm_data);
  

• }

+} diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h index e19ac7ca602d..476a422414f6 100644 --- a/drivers/gpu/drm/drm_internal.h +++ b/drivers/gpu/drm/drm_internal.h @@ -201,3 +201,7 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data, void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent, const struct drm_framebuffer *fb); int drm_framebuffer_debugfs_init(struct drm_minor *minor);

+/* drm_hdcp.c */ +int drm_setup_hdcp_srm(struct class *drm_class); +void drm_teardown_hdcp_srm(struct class *drm_class); diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c index ecb7b33002bb..18b1ac442997 100644 --- a/drivers/gpu/drm/drm_sysfs.c +++ b/drivers/gpu/drm/drm_sysfs.c @@ -78,6 +78,7 @@ int drm_sysfs_init(void) }

drm_class->devnode = drm_devnode;

• drm_setup_hdcp_srm(drm_class); return 0;

}

@@ -90,6 +91,7 @@ void drm_sysfs_destroy(void) { if (IS_ERR_OR_NULL(drm_class)) return;

• drm_teardown_hdcp_srm(drm_class); class_remove_file(drm_class, &class_attr_version.attr); class_destroy(drm_class); drm_class = NULL;

diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h index f243408ecf26..292998a2497f 100644 --- a/include/drm/drm_hdcp.h +++ b/include/drm/drm_hdcp.h @@ -265,4 +265,28 @@ void drm_hdcp2_u32_to_seq_num(u8 seq_num[HDCP_2_2_SEQ_NUM_LEN], u32 val) seq_num[2] = val; }

+#define DRM_HDCP_SRM_GEN1_MAX_BYTES (5 * 1024) +#define DRM_HDCP_1_4_SRM_ID 0x8 +#define DRM_HDCP_SRM_ID_MASK (0xF << 4)

This is surprising (I'd have expected the hdcp2 indicator in the low bits) from reading the spec. But I guess you tested this, and there's some mumbo-jumbo about "everything is big endian", which might also mean nibbles. Who knows.

+#define DRM_HDCP_1_4_VRL_LENGTH_SIZE 3 +#define DRM_HDCP_1_4_DCP_SIG_SIZE 40 +#define DRM_HDCP_2_SRM_ID 0x9 +#define DRM_HDCP_2_INDICATOR 0x1 +#define DRM_HDCP_2_INDICATOR_MASK 0xF +#define DRM_HDCP_2_VRL_LENGTH_SIZE 3 +#define DRM_HDCP_2_DCP_SIG_SIZE 384 +#define DRM_HDCP_2_NO_OF_DEV_PLUS_RESERVED_SZ 4 +#define DRM_HDCP_2_KSV_COUNT_2_LSBITS(byte) (((byte) & 0xC) >> 6)

+struct hdcp_srm_header {

• u8 srm_id;
• u8 reserved;
• u16 srm_version;

Needs to be __be16, so that sparse can validate you got all the byte swapping correct. Would be good to double-check with sparse yourself (otherwise 0day will do it for you, but if there's a problem better to catch it early).

• u8 srm_gen_no;

+} __packed;

+struct drm_device;

+bool drm_hdcp_check_ksvs_revoked(struct drm_device *dev,

• 		 u8 *ksvs, u32 ksv_count);
  

#endif

2.19.1

---

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