Adding a couple AMD guys.
I know this is already merged but I have a few questions after some internal discussions.
On 2019-05-07 12:27 p.m., Ramalingam C wrote:
On every hdcp revocation check request SRM is read from fw file /lib/firmware/display_hdcp_srm.bin
According to section 5 of the HDCP 2.3 spec [1] a device compliant with HDCP 2.0 and higher must be capable of storing and updating the SRM in non-volatile memory. Section 5.2 describes how this SRM needs to be updated when a new version is served alongside protected content.
Isn't /lib/firmware intended for static firmware making updates to the folder problematic for anyone but the system's package maintainer? I've heard /lib might even be treated as read-only in certain environments. This would mean it'd be impossible to support HDCP 2.x on those systems.
Wouldn't it be easier to provide a sysfs entry for SRM that allows userspace (e.g. system startup/shutdown scripts) to (a) retrieve the SRM from the HDCP implementation for non-volatile storage and (b) to pass the SRM to the HDCP implementation for revocation checking?
[1] https://www.digital-cp.com/sites/default/files/HDCP%20on%20HDMI%20Specificat...
Thanks, Harry
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] v4: s/__swab16/be16_to_cpu [Daniel] be24_to_cpu is done through a global func [Daniel] Unused variables are removed. [Daniel] unchecked return values are dropped from static funcs [Daniel]
Signed-off-by: Ramalingam C ramalingam.c@intel.com Acked-by: Satyeshwar Singh satyeshwar.singh@intel.com Reviewed-by: Daniel Vetter daniel@ffwll.ch
Documentation/gpu/drm-kms-helpers.rst | 6 + drivers/gpu/drm/Makefile | 2 +- drivers/gpu/drm/drm_hdcp.c | 333 ++++++++++++++++++++++++++ drivers/gpu/drm/drm_internal.h | 4 + drivers/gpu/drm/drm_sysfs.c | 2 + include/drm/drm_hdcp.h | 24 ++ 6 files changed, 370 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.odrm-$(CONFIG_DRM_LEGACY) += drm_legacy_misc.o drm_bufs.o drm_context.o drm_dma.o drm_scatter.o drm_lock.o drm-$(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..5e5409505c31 --- /dev/null +++ b/drivers/gpu/drm/drm_hdcp.c @@ -0,0 +1,333 @@ +// 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 {
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 drm_hdcp_be24_to_cpu(buf);+}
+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,be16_to_cpu(header->srm_version), header->srm_gen_no);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,be16_to_cpu(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 void drm_hdcp_srm_update(const u8 *buf, size_t count) +{
if (count < sizeof(struct hdcp_srm_header))return;if (is_srm_version_hdcp1(buf))drm_hdcp_parse_hdcp1_srm(buf, count);else if (is_srm_version_hdcp2(buf))drm_hdcp_parse_hdcp2_srm(buf, count);+}
+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;mutex_init(&srm_data->mutex);return 0;+}
+void drm_teardown_hdcp_srm(struct class *drm_class) +{
if (srm_data) {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 1cc66df05a43..2f0335d0a50f 100644 --- a/include/drm/drm_hdcp.h +++ b/include/drm/drm_hdcp.h @@ -265,4 +265,28 @@ void drm_hdcp_cpu_to_be24(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) +#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;__be16 srm_version;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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