ASoC: SOF: Add IPC3 Kernel Injector

Add debugfs path to fake a malicious firmware message for fuzzing purposes.

Skip IPC4 for initial integration

Signed-off-by: Curtis Malainey <cujomalainey@chromium.org>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi@linux.intel.com>
Link: https://lore.kernel.org/r/20230608221822.2825786-2-cujomalainey@chromium.org
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sof/Kconfig

@@ -236,6 +236,17 @@ config SND_SOC_SOF_DEBUG_IPC_MSG_INJECTOR
 	  Say Y if you want to enable the IPC message injector.
 	  If unsure, select "N".
 
+config SND_SOC_SOF_DEBUG_IPC_KERNEL_INJECTOR
+	tristate "SOF enable IPC kernel injector"
+	depends on SND_SOC_SOF
+	select SND_SOC_SOF_CLIENT
+	help
+	  This option enables the IPC kernel injector which can be used to send
+	  crafted IPC messages to the kernel to test its robustness against
+	  DSP messages.
+	  Say Y if you want to enable the IPC kernel injector.
+	  If unsure, select "N".
+
 config SND_SOC_SOF_DEBUG_RETAIN_DSP_CONTEXT
 	bool "SOF retain DSP context on any FW exceptions"
 	help

sound/soc/sof/Makefile

@@ -26,6 +26,7 @@ snd-sof-of-objs := sof-of-dev.o
 
 snd-sof-ipc-flood-test-objs := sof-client-ipc-flood-test.o
 snd-sof-ipc-msg-injector-objs := sof-client-ipc-msg-injector.o
+snd-sof-ipc-kernel-injector-objs := sof-client-ipc-kernel-injector.o
 snd-sof-probes-objs := sof-client-probes.o
 ifneq ($(CONFIG_SND_SOC_SOF_IPC3),)
 snd-sof-probes-objs += sof-client-probes-ipc3.o
@@ -49,6 +50,7 @@ obj-$(CONFIG_SND_SOC_SOF_PCI_DEV) += snd-sof-pci.o
 
 obj-$(CONFIG_SND_SOC_SOF_DEBUG_IPC_FLOOD_TEST) += snd-sof-ipc-flood-test.o
 obj-$(CONFIG_SND_SOC_SOF_DEBUG_IPC_MSG_INJECTOR) += snd-sof-ipc-msg-injector.o
+obj-$(CONFIG_SND_SOC_SOF_DEBUG_IPC_KERNEL_INJECTOR) += snd-sof-ipc-kernel-injector.o
 obj-$(CONFIG_SND_SOC_SOF_DEBUG_PROBES) += snd-sof-probes.o
 
 obj-$(CONFIG_SND_SOC_SOF_INTEL_TOPLEVEL) += intel/

sound/soc/sof/sof-client-ipc-kernel-injector.c

@@ -0,0 +1,162 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// Copyright(c) 2023 Google Inc. All rights reserved.
+//
+// Author: Curtis Malainey <cujomalainey@chromium.org>
+//
+
+#include <linux/auxiliary_bus.h>
+#include <linux/debugfs.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <sound/sof/header.h>
+
+#include "sof-client.h"
+
+#define SOF_IPC_CLIENT_SUSPEND_DELAY_MS	3000
+
+struct sof_msg_inject_priv {
+	struct dentry *kernel_dfs_file;
+	size_t max_msg_size;
+
+	void *kernel_buffer;
+};
+
+static int sof_msg_inject_dfs_open(struct inode *inode, struct file *file)
+{
+	int ret = debugfs_file_get(file->f_path.dentry);
+
+	if (unlikely(ret))
+		return ret;
+
+	ret = simple_open(inode, file);
+	if (ret)
+		debugfs_file_put(file->f_path.dentry);
+
+	return ret;
+}
+
+static ssize_t sof_kernel_msg_inject_dfs_write(struct file *file, const char __user *buffer,
+					       size_t count, loff_t *ppos)
+{
+	struct sof_client_dev *cdev = file->private_data;
+	struct sof_msg_inject_priv *priv = cdev->data;
+	struct sof_ipc_cmd_hdr *hdr = priv->kernel_buffer;
+	struct device *dev = &cdev->auxdev.dev;
+	ssize_t size;
+	int ret;
+
+	if (*ppos)
+		return 0;
+
+	size = simple_write_to_buffer(priv->kernel_buffer, priv->max_msg_size,
+				      ppos, buffer, count);
+	if (size < 0)
+		return size;
+	if (size != count)
+		return -EFAULT;
+
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0 && ret != -EACCES) {
+		dev_err_ratelimited(dev, "debugfs write failed to resume %d\n", ret);
+		return ret;
+	}
+
+	sof_client_ipc_rx_message(cdev, hdr, priv->kernel_buffer);
+
+	pm_runtime_mark_last_busy(dev);
+	ret = pm_runtime_put_autosuspend(dev);
+	if (ret < 0)
+		dev_err_ratelimited(dev, "debugfs write failed to idle %d\n", ret);
+
+	return count;
+};
+
+static int sof_msg_inject_dfs_release(struct inode *inode, struct file *file)
+{
+	debugfs_file_put(file->f_path.dentry);
+
+	return 0;
+}
+
+static const struct file_operations sof_kernel_msg_inject_fops = {
+	.open = sof_msg_inject_dfs_open,
+	.write = sof_kernel_msg_inject_dfs_write,
+	.release = sof_msg_inject_dfs_release,
+
+	.owner = THIS_MODULE,
+};
+
+static int sof_msg_inject_probe(struct auxiliary_device *auxdev,
+				const struct auxiliary_device_id *id)
+{
+	struct sof_client_dev *cdev = auxiliary_dev_to_sof_client_dev(auxdev);
+	struct dentry *debugfs_root = sof_client_get_debugfs_root(cdev);
+	struct device *dev = &auxdev->dev;
+	struct sof_msg_inject_priv *priv;
+	size_t alloc_size;
+
+	/* allocate memory for client data */
+	priv = devm_kzalloc(&auxdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->max_msg_size = sof_client_get_ipc_max_payload_size(cdev);
+	alloc_size = priv->max_msg_size;
+	priv->kernel_buffer = devm_kmalloc(dev, alloc_size, GFP_KERNEL);
+
+	if (!priv->kernel_buffer)
+		return -ENOMEM;
+
+	cdev->data = priv;
+
+	priv->kernel_dfs_file = debugfs_create_file("kernel_ipc_msg_inject", 0644,
+						    debugfs_root, cdev,
+						    &sof_kernel_msg_inject_fops);
+
+	/* enable runtime PM */
+	pm_runtime_set_autosuspend_delay(dev, SOF_IPC_CLIENT_SUSPEND_DELAY_MS);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_active(dev);
+	pm_runtime_enable(dev);
+	pm_runtime_mark_last_busy(dev);
+	pm_runtime_idle(dev);
+
+	return 0;
+}
+
+static void sof_msg_inject_remove(struct auxiliary_device *auxdev)
+{
+	struct sof_client_dev *cdev = auxiliary_dev_to_sof_client_dev(auxdev);
+	struct sof_msg_inject_priv *priv = cdev->data;
+
+	pm_runtime_disable(&auxdev->dev);
+
+	debugfs_remove(priv->kernel_dfs_file);
+}
+
+static const struct auxiliary_device_id sof_msg_inject_client_id_table[] = {
+	{ .name = "snd_sof.kernel_injector" },
+	{},
+};
+MODULE_DEVICE_TABLE(auxiliary, sof_msg_inject_client_id_table);
+
+/*
+ * No need for driver pm_ops as the generic pm callbacks in the auxiliary bus
+ * type are enough to ensure that the parent SOF device resumes to bring the DSP
+ * back to D0.
+ * Driver name will be set based on KBUILD_MODNAME.
+ */
+static struct auxiliary_driver sof_msg_inject_client_drv = {
+	.probe = sof_msg_inject_probe,
+	.remove = sof_msg_inject_remove,
+
+	.id_table = sof_msg_inject_client_id_table,
+};
+
+module_auxiliary_driver(sof_msg_inject_client_drv);
+
+MODULE_DESCRIPTION("SOF IPC Kernel Injector Client Driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS(SND_SOC_SOF_CLIENT);

sound/soc/sof/sof-client.c

@@ -16,6 +16,7 @@
 #include "ops.h"
 #include "sof-client.h"
 #include "sof-priv.h"
+#include "ipc3-priv.h"
 #include "ipc4-priv.h"
 
 /**
@@ -126,6 +127,29 @@ static inline int sof_register_ipc_msg_injector(struct snd_sof_dev *sdev)
 static inline void sof_unregister_ipc_msg_injector(struct snd_sof_dev *sdev) {}
 #endif /* CONFIG_SND_SOC_SOF_DEBUG_IPC_MSG_INJECTOR */
 
+#if IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_IPC_KERNEL_INJECTOR)
+static int sof_register_ipc_kernel_injector(struct snd_sof_dev *sdev)
+{
+	/* Only IPC3 supported right now */
+	if (sdev->pdata->ipc_type != SOF_IPC)
+		return 0;
+
+	return sof_client_dev_register(sdev, "kernel_injector", 0, NULL, 0);
+}
+
+static void sof_unregister_ipc_kernel_injector(struct snd_sof_dev *sdev)
+{
+	sof_client_dev_unregister(sdev, "kernel_injector", 0);
+}
+#else
+static inline int sof_register_ipc_kernel_injector(struct snd_sof_dev *sdev)
+{
+	return 0;
+}
+
+static inline void sof_unregister_ipc_kernel_injector(struct snd_sof_dev *sdev) {}
+#endif /* CONFIG_SND_SOC_SOF_DEBUG_IPC_KERNEL_INJECTOR */
+
 int sof_register_clients(struct snd_sof_dev *sdev)
 {
 	int ret;
@@ -146,6 +170,12 @@ int sof_register_clients(struct snd_sof_dev *sdev)
 		goto err_msg_injector;
 	}
 
+	ret = sof_register_ipc_kernel_injector(sdev);
+	if (ret) {
+		dev_err(sdev->dev, "IPC kernel injector client registration failed\n");
+		goto err_kernel_injector;
+	}
+
 	/* Platform depndent client device registration */
 
 	if (sof_ops(sdev) && sof_ops(sdev)->register_ipc_clients)
@@ -154,6 +184,9 @@ int sof_register_clients(struct snd_sof_dev *sdev)
 	if (!ret)
 		return 0;
 
+	sof_unregister_ipc_kernel_injector(sdev);
+
+err_kernel_injector:
 	sof_unregister_ipc_msg_injector(sdev);
 
 err_msg_injector:
@@ -167,6 +200,7 @@ void sof_unregister_clients(struct snd_sof_dev *sdev)
 	if (sof_ops(sdev) && sof_ops(sdev)->unregister_ipc_clients)
 		sof_ops(sdev)->unregister_ipc_clients(sdev);
 
+	sof_unregister_ipc_kernel_injector(sdev);
 	sof_unregister_ipc_msg_injector(sdev);
 	sof_unregister_ipc_flood_test(sdev);
 }
@@ -269,6 +303,24 @@ int sof_client_ipc_tx_message(struct sof_client_dev *cdev, void *ipc_msg,
 }
 EXPORT_SYMBOL_NS_GPL(sof_client_ipc_tx_message, SND_SOC_SOF_CLIENT);
 
+int sof_client_ipc_rx_message(struct sof_client_dev *cdev, void *ipc_msg, void *msg_buf)
+{
+	if (cdev->sdev->pdata->ipc_type == SOF_IPC) {
+		struct sof_ipc_cmd_hdr *hdr = ipc_msg;
+
+		if (hdr->size < sizeof(hdr)) {
+			dev_err(cdev->sdev->dev, "The received message size is invalid\n");
+			return -EINVAL;
+		}
+
+		sof_ipc3_do_rx_work(cdev->sdev, ipc_msg, msg_buf);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+EXPORT_SYMBOL_NS_GPL(sof_client_ipc_rx_message, SND_SOC_SOF_CLIENT);
+
 int sof_client_ipc_set_get_data(struct sof_client_dev *cdev, void *ipc_msg,
 				bool set)
 {

sound/soc/sof/sof-client.h

@@ -75,5 +75,6 @@ int sof_client_register_fw_state_handler(struct sof_client_dev *cdev,
 					 sof_client_fw_state_callback callback);
 void sof_client_unregister_fw_state_handler(struct sof_client_dev *cdev);
 enum sof_fw_state sof_client_get_fw_state(struct sof_client_dev *cdev);
+int sof_client_ipc_rx_message(struct sof_client_dev *cdev, void *ipc_msg, void *msg_buf);
 
 #endif /* __SOC_SOF_CLIENT_H */