drm: revocation check at drm subsystem

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]
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>
Acked-by: Dave Airlie <airlied@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20190507162745.25600-5-ramalingam.c@intel.com
This commit is contained in:
Ramalingam C 2019-05-07 21:57:38 +05:30 committed by Daniel Vetter
parent 0de655cae4
commit 6498bf5800
6 changed files with 370 additions and 1 deletions

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@ -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
=======================================

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@ -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

333
drivers/gpu/drm/drm_hdcp.c Normal file
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@ -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);
}
}

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@ -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);

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@ -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;

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@ -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