Re: [PATCH v8 08/35] drm/i915: Implement HDCP2.2 repeater authentication

["C, Ramalingam" <ramalingam.c@intel.com>]

On 12/6/2018 4:15 PM, Daniel Vetter wrote:
> On Tue, Nov 27, 2018 at 04:13:06PM +0530, Ramalingam C wrote:
>> Implements the HDCP2.2 repeaters authentication steps such as verifying
>> the downstream topology and sending stream management information.
>>
>> v2:
>>    Rebased.
>> v3:
>>    No Changes.
>> v4:
>>    -EINVAL is returned for topology error and rollover scenario.
>>    Endianness conversion func from drm_hdcp.h is used [Uma]
>> v5:
>>    Rebased as part of patches reordering.
>>    Defined the mei service functions [Daniel]
>> v6:
>>    Redefined the mei service functions as per comp redesign.
>> v7:
>>    %s/uintxx_t/uxx
>>    Check for comp_master is removed.
>> v8:
>>    Adjust to the new mei interface.
>>    style issue fixed.
>>
>> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
>> ---
>>   drivers/gpu/drm/i915/intel_hdcp.c | 125 +++++++++++++++++++++++++++++++++++++-
>>   include/drm/drm_hdcp.h            |  15 +++++
>>   2 files changed, 138 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_hdcp.c b/drivers/gpu/drm/i915/intel_hdcp.c
>> index 0d7fea9c9bb1..679f3c164582 100644
>> --- a/drivers/gpu/drm/i915/intel_hdcp.c
>> +++ b/drivers/gpu/drm/i915/intel_hdcp.c
>> @@ -1069,7 +1069,7 @@ static int hdcp2_prepare_skey(struct intel_connector *connector,
>>   	return ret;
>>   }
>>   
>> -static __attribute__((unused)) int
>> +static int
>>   hdcp2_verify_rep_topology_prepare_ack(struct intel_connector *connector,
>>   				      struct hdcp2_rep_send_receiverid_list
>>   								*rep_topology,
>> @@ -1099,7 +1099,7 @@ hdcp2_verify_rep_topology_prepare_ack(struct intel_connector *connector,
>>   	return ret;
>>   }
>>   
>> -static __attribute__((unused)) int
>> +static int
>>   hdcp2_verify_mprime(struct intel_connector *connector,
>>   		    struct hdcp2_rep_stream_ready *stream_ready)
>>   {
>> @@ -1315,6 +1315,121 @@ static int hdcp2_session_key_exchange(struct intel_connector *connector)
>>   	return 0;
>>   }
>>   
>> +static
>> +int hdcp2_propagate_stream_management_info(struct intel_connector *connector)
>> +{
>> +	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
>> +	struct intel_hdcp *hdcp = &connector->hdcp;
>> +	union {
>> +		struct hdcp2_rep_stream_manage stream_manage;
>> +		struct hdcp2_rep_stream_ready stream_ready;
>> +	} msgs;
>> +	const struct intel_hdcp_shim *shim = hdcp->shim;
>> +	int ret;
>> +
>> +	/* Prepare RepeaterAuth_Stream_Manage msg */
>> +	msgs.stream_manage.msg_id = HDCP_2_2_REP_STREAM_MANAGE;
>> +	reverse_endianness(msgs.stream_manage.seq_num_m, HDCP_2_2_SEQ_NUM_LEN,
>> +			   (u8 *)&hdcp->seq_num_m);
>> +
>> +	/* K no of streams is fixed as 1. Stored as big-endian. */
>> +	msgs.stream_manage.k = __swab16(1);
>> +
>> +	/* For HDMI this is forced to be 0x0. For DP SST also this is 0x0. */
>> +	msgs.stream_manage.streams[0].stream_id = 0;
>> +	msgs.stream_manage.streams[0].stream_type = hdcp->content_type;
>> +
>> +	/* Send it to Repeater */
>> +	ret = shim->write_2_2_msg(intel_dig_port, &msgs.stream_manage,
>> +				  sizeof(msgs.stream_manage));
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = shim->read_2_2_msg(intel_dig_port, HDCP_2_2_REP_STREAM_READY,
>> +				 &msgs.stream_ready, sizeof(msgs.stream_ready));
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	hdcp->mei_data.seq_num_m = hdcp->seq_num_m;
>> +	hdcp->mei_data.streams[0].stream_type = hdcp->content_type;
>> +
>> +	ret = hdcp2_verify_mprime(connector, &msgs.stream_ready);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	hdcp->seq_num_m++;
>> +
>> +	if (hdcp->seq_num_m > HDCP_2_2_SEQ_NUM_MAX) {
>> +		DRM_DEBUG_KMS("seq_num_m roll over.\n");
>> +		return -1;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static
>> +int hdcp2_authenticate_repeater_topology(struct intel_connector *connector)
>> +{
>> +	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
>> +	struct intel_hdcp *hdcp = &connector->hdcp;
>> +	union {
>> +		struct hdcp2_rep_send_receiverid_list recvid_list;
>> +		struct hdcp2_rep_send_ack rep_ack;
>> +	} msgs;
>> +	const struct intel_hdcp_shim *shim = hdcp->shim;
>> +	u8 *rx_info;
>> +	u32 seq_num_v;
>> +	int ret;
>> +
>> +	ret = shim->read_2_2_msg(intel_dig_port, HDCP_2_2_REP_SEND_RECVID_LIST,
>> +				 &msgs.recvid_list, sizeof(msgs.recvid_list));
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	rx_info = msgs.recvid_list.rx_info;
>> +
>> +	if (HDCP_2_2_MAX_CASCADE_EXCEEDED(rx_info[1]) ||
>> +	    HDCP_2_2_MAX_DEVS_EXCEEDED(rx_info[1])) {
>> +		DRM_DEBUG_KMS("Topology Max Size Exceeded\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* Converting and Storing the seq_num_v to local variable as DWORD */
>> +	reverse_endianness((u8 *)&seq_num_v, HDCP_2_2_SEQ_NUM_LEN,
>> +			   msgs.recvid_list.seq_num_v);
>> +
>> +	if (seq_num_v < hdcp->seq_num_v) {
>> +		/* Roll over of the seq_num_v from repeater. Reauthenticate. */
>> +		DRM_DEBUG_KMS("Seq_num_v roll over.\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	ret = hdcp2_verify_rep_topology_prepare_ack(connector,
>> +						    &msgs.recvid_list,
>> +						    &msgs.rep_ack);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	hdcp->seq_num_v = seq_num_v;
>> +	ret = shim->write_2_2_msg(intel_dig_port, &msgs.rep_ack,
>> +				  sizeof(msgs.rep_ack));
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static int hdcp2_authenticate_repeater(struct intel_connector *connector)
>> +{
>> +	int ret;
>> +
>> +	ret = hdcp2_authenticate_repeater_topology(connector);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return hdcp2_propagate_stream_management_info(connector);
>> +}
>> +
>>   static int hdcp2_authenticate_sink(struct intel_connector *connector)
>>   {
>>   	struct intel_digital_port *intel_dig_port = conn_to_dig_port(connector);
>> @@ -1356,6 +1471,12 @@ static int hdcp2_authenticate_sink(struct intel_connector *connector)
>>   					       sizeof(stream_type_msg));
>>   		if (ret < 0)
>>   			return ret;
>> +	} else if (hdcp->is_repeater) {
>> +		ret = hdcp2_authenticate_repeater(connector);
>> +		if (ret < 0) {
>> +			DRM_DEBUG_KMS("Repeater Auth Failed. Err: %d\n", ret);
>> +			return ret;
>> +		}
>>   	}
>>   
>>   	hdcp->mei_data.streams[0].stream_type = hdcp->content_type;
>> diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h
>> index a6de09c5e47f..3e45a7618ab3 100644
>> --- a/include/drm/drm_hdcp.h
>> +++ b/include/drm/drm_hdcp.h
>> @@ -250,4 +250,19 @@ struct hdcp2_dp_errata_stream_type {
>>   #define HDCP_2_2_HDMI_RXSTATUS_READY(x)		((x) & BIT(2))
>>   #define HDCP_2_2_HDMI_RXSTATUS_REAUTH_REQ(x)	((x) & BIT(3))
>>   
>> +/*
>> + * Library functions for endianness are aligned for 16/32/64 bits.
>> + * But hdcp sequence numbers are 24bits. So for their Byte swapping,
>> + * a conversion function is developed.
>> + */
>> +static inline void reverse_endianness(u8 *dest, size_t sz, u8 *src)
> This feels a bit fake-generic and doesn't fit that well into what you want
> it to do in the code actually. What about:
>
> u32 drm_hdcp2_seq_num_to_u32(u8 seq_num[HDCP_2_2_SEQ_NUM_LEN])
> {
> 	return seq_num[2] | seq_num[1] << 8 | seq_num[0] << 16;
> }

Understood the point. we need drm_hdcp2_u32_to_seq_num too... I will add 
that too.

-Ram

>
> (I didn't check the math).
>
> I think this would both make the code more clearer and avoid the problem
> of "shouldn't we make sure this works for everything and put it into
> linux/string.h?"
>
> Again I'll check the actual hdcp2 flow later on.
>
> In general I'm kinda not happy with the shim midlayer design, but I wasn't
> happy with that with hdcp1 either, and hdcp2 is just an extension, and I
> don't really have a better idea either so seems all good to me.
> -Daniel
>
>> +{
>> +	u32 index;
>> +
>> +	if (!sz || sz > sizeof(u32))
>> +		return;
>> +	for (index = 0; index < sz; index++)
>> +		dest[sz - index - 1] = src[index];
>> +}
>> +
>>   #endif
>> -- 
>> 2.7.4
>>
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel