linux-kernel - [PATCH v2 3/3] dp_hdcp: Get the hdcp key from the connector prop

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20230421162749.360777-4-markyacoub@google.com>
Date:   Fri, 21 Apr 2023 12:27:49 -0400
From:   Mark Yacoub <markyacoub@...omium.org>
To:     dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>
Cc:     seanpaul@...omium.org, dianders@...omium.org,
        Mark Yacoub <markyacoub@...omium.org>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/3] dp_hdcp: Get the hdcp key from the connector prop

From: Mark Yacoub <markyacoub@...omium.org>

[Why]
To support protected content, the driver requires a key.
Currently, it's being injected from debugfs, which is not super useful
to run a user space in the wild.

[How]
When the key is needed, fetch the "Content Protection Property" on the
connector and get the key blob. Verify that the size is valid and use
it.

Signed-off-by: Mark Yacoub <markyacoub@...omium.org>
---
 drivers/gpu/drm/msm/dp/dp_hdcp.c | 66 +++++++++++++++++++++++++++++---
 1 file changed, 61 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_hdcp.c b/drivers/gpu/drm/msm/dp/dp_hdcp.c
index 191340971f943..4321d245b36c9 100644
--- a/drivers/gpu/drm/msm/dp/dp_hdcp.c
+++ b/drivers/gpu/drm/msm/dp/dp_hdcp.c
@@ -117,19 +117,61 @@ static bool dp_hdcp_are_keys_valid(struct drm_connector *connector,
 	return FIELD_GET(DP_HDCP_KEY_STATUS, val) == DP_HDCP_KEY_STATUS_VALID;
 }
 
+static bool dp_hdcp_get_key_from_connector(struct drm_connector *connector,
+					   struct drm_bridge *bridge)
+{
+	struct drm_property_blob *key_blob;
+	u8 *raw_key;
+	int ret;
+	struct dp_hdcp *hdcp;
+	struct drm_device *dev = connector->dev;
+	struct drm_property *prop =
+		dev->mode_config.content_protection_key_property;
+
+	if (!prop)
+		return false;
+
+	key_blob = connector->state->content_protection_key;
+	if (!key_blob)
+		return false;
+
+	raw_key = key_blob->data;
+
+	if (key_blob->length !=
+	    DRM_HDCP_KSV_LEN + DP_HDCP_NUM_KEYS * DP_HDCP_KEY_LEN) {
+		drm_dbg_atomic(
+			dev,
+			"[CONNECTOR:%d:%s] Content Protection Key is a blob that we don't expect.\n",
+			connector->base.id, connector->name);
+		return false;
+	}
+
+	hdcp = dp_display_bridge_to_hdcp(bridge);
+	ret = dp_hdcp_ingest_key(hdcp, key_blob->data, key_blob->length);
+	if (ret)
+		return false;
+
+	return true;
+}
+
 static int dp_hdcp_load_keys(struct drm_connector *connector, void *driver_data)
 {
 	struct drm_bridge *bridge = (struct drm_bridge *)driver_data;
 	struct dp_hdcp *hdcp = dp_display_bridge_to_hdcp(bridge);
 	int i, ret = 0;
+	bool is_hdcp_key_valid;
 
 	mutex_lock(&hdcp->key_lock);
+	is_hdcp_key_valid = hdcp->key.valid;
+	mutex_unlock(&hdcp->key_lock);
 
-	if (!hdcp->key.valid) {
-		ret = -ENOENT;
-		goto out;
+	if (!is_hdcp_key_valid &&
+	    !dp_hdcp_get_key_from_connector(connector, bridge)) {
+		return -ENOENT;
 	}
 
+	mutex_lock(&hdcp->key_lock);
+
 	dp_catalog_hdcp_write_aksv(hdcp->catalog, hdcp->key.ksv.words);
 
 
@@ -139,7 +181,6 @@ static int dp_hdcp_load_keys(struct drm_connector *connector, void *driver_data)
 	}
 	dp_catalog_hdcp_post_write_key(hdcp->catalog);
 
-out:
 	mutex_unlock(&hdcp->key_lock);
 	return ret;
 }
@@ -346,6 +387,8 @@ int dp_hdcp_attach(struct dp_hdcp *hdcp, struct drm_connector *connector,
 		   struct drm_bridge *bridge, struct dp_catalog *catalog)
 {
 	struct drm_hdcp_helper_data *helper_data;
+	struct drm_device *dev;
+	struct drm_property *prop;
 
 	/* HDCP is not configured for this device */
 	if (!hdcp->parser->io.dp_controller.hdcp_key.base)
@@ -357,7 +400,20 @@ int dp_hdcp_attach(struct dp_hdcp *hdcp, struct drm_connector *connector,
 		return PTR_ERR(helper_data);
 
 	helper_data->driver_data = bridge;
-	hdcp->dev = connector->dev;
+
+	dev = connector->dev;
+	prop = dev->mode_config.content_protection_key_property;
+	if (!prop) {
+		prop = drm_property_create(dev, DRM_MODE_PROP_BLOB,
+					   "Content Protection Key", 0);
+	}
+	if (!prop)
+		return -1;
+	drm_object_attach_property(&connector->base, prop,
+				   DRM_MODE_HDCP_CONTENT_TYPE0);
+	dev->mode_config.content_protection_key_property = prop;
+
+	hdcp->dev = dev;
 	hdcp->connector = connector;
 	hdcp->helper_data = helper_data;
 	hdcp->catalog = catalog;
-- 
2.40.0.634.g4ca3ef3211-goog