drivers/virt/coco/tdx-guest/tdx-guest.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * TDX guest user interface driver
  *
  * Copyright (C) 2022 Intel Corporation
  */

 #include <linux/kernel.h>
 #include <linux/miscdevice.h>
 #include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/string.h>
 #include <linux/uaccess.h>
 #include <linux/set_memory.h>
 #include <linux/io.h>
 #include <linux/delay.h>
 #include <linux/tsm.h>
 #include <linux/sizes.h>

 #include <uapi/linux/tdx-guest.h>

 #include <asm/cpu_device_id.h>
 #include <asm/tdx.h>

 /*
  * Intel's SGX QE implementation generally uses Quote size less
  * than 8K (2K Quote data + ~5K of certificate blob).
  */
 #define GET_QUOTE_BUF_SIZE		SZ_8K

 #define GET_QUOTE_CMD_VER		1

 /* TDX GetQuote status codes */
 #define GET_QUOTE_SUCCESS		0
 #define GET_QUOTE_IN_FLIGHT		0xffffffffffffffff

 /* struct tdx_quote_buf: Format of Quote request buffer.
  * @version: Quote format version, filled by TD.
  * @status: Status code of Quote request, filled by VMM.
  * @in_len: Length of TDREPORT, filled by TD.
  * @out_len: Length of Quote data, filled by VMM.
  * @data: Quote data on output or TDREPORT on input.
  *
  * More details of Quote request buffer can be found in TDX
  * Guest-Host Communication Interface (GHCI) for Intel TDX 1.0,
  * section titled "TDG.VP.VMCALL<GetQuote>"
  */
 struct tdx_quote_buf {
 	u64 version;
 	u64 status;
 	u32 in_len;
 	u32 out_len;
 	u8 data[];
 };

 /* Quote data buffer */
 static void *quote_data;

 /* Lock to streamline quote requests */
 static DEFINE_MUTEX(quote_lock);

 /*
  * GetQuote request timeout in seconds. Expect that 30 seconds
  * is enough time for QE to respond to any Quote requests.
  */
 static u32 getquote_timeout = 30;

 static long tdx_get_report0(struct tdx_report_req __user *req)
 {
 	u8 *reportdata, *tdreport;
 	long ret;

 	reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);
 	if (!reportdata)
 		return -ENOMEM;

 	tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);
 	if (!tdreport) {
 		ret = -ENOMEM;
 		goto out;
 	}

 	if (copy_from_user(reportdata, req->reportdata, TDX_REPORTDATA_LEN)) {
 		ret = -EFAULT;
 		goto out;
 	}

 	/* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */
 	ret = tdx_mcall_get_report0(reportdata, tdreport);
 	if (ret)
 		goto out;

 	if (copy_to_user(req->tdreport, tdreport, TDX_REPORT_LEN))
 		ret = -EFAULT;

 out:
 	kfree(reportdata);
 	kfree(tdreport);

 	return ret;
 }

 static void free_quote_buf(void *buf)
 {
 	size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);
 	unsigned int count = len >> PAGE_SHIFT;

 	if (set_memory_encrypted((unsigned long)buf, count)) {
 		pr_err("Failed to restore encryption mask for Quote buffer, leak it\n");
 		return;
 	}

 	free_pages_exact(buf, len);
 }

 static void *alloc_quote_buf(void)
 {
 	size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);
 	unsigned int count = len >> PAGE_SHIFT;
 	void *addr;

 	addr = alloc_pages_exact(len, GFP_KERNEL | __GFP_ZERO);
 	if (!addr)
 		return NULL;

 	if (set_memory_decrypted((unsigned long)addr, count)) {
 		free_pages_exact(addr, len);
 		return NULL;
 	}

 	return addr;
 }

 /*
  * wait_for_quote_completion() - Wait for Quote request completion
  * @quote_buf: Address of Quote buffer.
  * @timeout: Timeout in seconds to wait for the Quote generation.
  *
  * As per TDX GHCI v1.0 specification, sec titled "TDG.VP.VMCALL<GetQuote>",
  * the status field in the Quote buffer will be set to GET_QUOTE_IN_FLIGHT
  * while VMM processes the GetQuote request, and will change it to success
  * or error code after processing is complete. So wait till the status
  * changes from GET_QUOTE_IN_FLIGHT or the request being timed out.
  */
 static int wait_for_quote_completion(struct tdx_quote_buf *quote_buf, u32 timeout)
 {
 	int i = 0;

 	/*
 	 * Quote requests usually take a few seconds to complete, so waking up
 	 * once per second to recheck the status is fine for this use case.
 	 */
 	while (quote_buf->status == GET_QUOTE_IN_FLIGHT && i++ < timeout) {
 		if (msleep_interruptible(MSEC_PER_SEC))
 			return -EINTR;
 	}

 	return (i == timeout) ? -ETIMEDOUT : 0;
 }

 static int tdx_report_new(struct tsm_report *report, void *data)
 {
 	u8 *buf, *reportdata = NULL, *tdreport = NULL;
 	struct tdx_quote_buf *quote_buf = quote_data;
 	struct tsm_desc *desc = &report->desc;
 	int ret;
 	u64 err;

 	/* TODO: switch to guard(mutex_intr) */
 	if (mutex_lock_interruptible(&quote_lock))
 		return -EINTR;

 	/*
 	 * If the previous request is timedout or interrupted, and the
 	 * Quote buf status is still in GET_QUOTE_IN_FLIGHT (owned by
 	 * VMM), don't permit any new request.
 	 */
 	if (quote_buf->status == GET_QUOTE_IN_FLIGHT) {
 		ret = -EBUSY;
 		goto done;
 	}

 	if (desc->inblob_len != TDX_REPORTDATA_LEN) {
 		ret = -EINVAL;
 		goto done;
 	}

 	reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);
 	if (!reportdata) {
 		ret = -ENOMEM;
 		goto done;
 	}

 	tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);
 	if (!tdreport) {
 		ret = -ENOMEM;
 		goto done;
 	}

 	memcpy(reportdata, desc->inblob, desc->inblob_len);

 	/* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */
 	ret = tdx_mcall_get_report0(reportdata, tdreport);
 	if (ret) {
 		pr_err("GetReport call failed\n");
 		goto done;
 	}

 	memset(quote_data, 0, GET_QUOTE_BUF_SIZE);

 	/* Update Quote buffer header */
 	quote_buf->version = GET_QUOTE_CMD_VER;
 	quote_buf->in_len = TDX_REPORT_LEN;

 	memcpy(quote_buf->data, tdreport, TDX_REPORT_LEN);

 	err = tdx_hcall_get_quote(quote_data, GET_QUOTE_BUF_SIZE);
 	if (err) {
 		pr_err("GetQuote hypercall failed, status:%llx\n", err);
 		ret = -EIO;
 		goto done;
 	}

 	ret = wait_for_quote_completion(quote_buf, getquote_timeout);
 	if (ret) {
 		pr_err("GetQuote request timedout\n");
 		goto done;
 	}

 	buf = kvmemdup(quote_buf->data, quote_buf->out_len, GFP_KERNEL);
 	if (!buf) {
 		ret = -ENOMEM;
 		goto done;
 	}

 	report->outblob = buf;
 	report->outblob_len = quote_buf->out_len;

 	/*
 	 * TODO: parse the PEM-formatted cert chain out of the quote buffer when
 	 * provided
 	 */
 done:
 	mutex_unlock(&quote_lock);
 	kfree(reportdata);
 	kfree(tdreport);

 	return ret;
 }

 static long tdx_guest_ioctl(struct file *file, unsigned int cmd,
 			    unsigned long arg)
 {
 	switch (cmd) {
 	case TDX_CMD_GET_REPORT0:
 		return tdx_get_report0((struct tdx_report_req __user *)arg);
 	default:
 		return -ENOTTY;
 	}
 }

 static const struct file_operations tdx_guest_fops = {
 	.owner = THIS_MODULE,
 	.unlocked_ioctl = tdx_guest_ioctl,
 	.llseek = no_llseek,
 };

 static struct miscdevice tdx_misc_dev = {
 	.name = KBUILD_MODNAME,
 	.minor = MISC_DYNAMIC_MINOR,
 	.fops = &tdx_guest_fops,
 };

 static const struct x86_cpu_id tdx_guest_ids[] = {
 	X86_MATCH_FEATURE(X86_FEATURE_TDX_GUEST, NULL),
 	{}
 };
 MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids);

 static const struct tsm_ops tdx_tsm_ops = {
 	.name = KBUILD_MODNAME,
 	.report_new = tdx_report_new,
 };

 static int __init tdx_guest_init(void)
 {
 	int ret;

 	if (!x86_match_cpu(tdx_guest_ids))
 		return -ENODEV;

 	ret = misc_register(&tdx_misc_dev);
 	if (ret)
 		return ret;

 	quote_data = alloc_quote_buf();
 	if (!quote_data) {
 		pr_err("Failed to allocate Quote buffer\n");
 		ret = -ENOMEM;
 		goto free_misc;
 	}

 	ret = tsm_register(&tdx_tsm_ops, NULL, NULL);
 	if (ret)
 		goto free_quote;

 	return 0;

 free_quote:
 	free_quote_buf(quote_data);
 free_misc:
 	misc_deregister(&tdx_misc_dev);

 	return ret;
 }
 module_init(tdx_guest_init);

 static void __exit tdx_guest_exit(void)
 {
 	tsm_unregister(&tdx_tsm_ops);
 	free_quote_buf(quote_data);
 	misc_deregister(&tdx_misc_dev);
 }
 module_exit(tdx_guest_exit);

 MODULE_AUTHOR("Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>");
 MODULE_DESCRIPTION("TDX Guest Driver");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* TDX guest user interface driver
	*
	* Copyright (C) 2022 Intel Corporation
	*/

	#include <linux/kernel.h>
	#include <linux/miscdevice.h>
	#include <linux/mm.h>
	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/string.h>
	#include <linux/uaccess.h>
	#include <linux/set_memory.h>
	#include <linux/io.h>
	#include <linux/delay.h>
	#include <linux/tsm.h>
	#include <linux/sizes.h>

	#include <uapi/linux/tdx-guest.h>

	#include <asm/cpu_device_id.h>
	#include <asm/tdx.h>

	/*
	* Intel's SGX QE implementation generally uses Quote size less
	* than 8K (2K Quote data + ~5K of certificate blob).
	*/
	#define GET_QUOTE_BUF_SIZE SZ_8K

	#define GET_QUOTE_CMD_VER 1

	/* TDX GetQuote status codes */
	#define GET_QUOTE_SUCCESS 0
	#define GET_QUOTE_IN_FLIGHT 0xffffffffffffffff

	/* struct tdx_quote_buf: Format of Quote request buffer.
	* @version: Quote format version, filled by TD.
	* @status: Status code of Quote request, filled by VMM.
	* @in_len: Length of TDREPORT, filled by TD.
	* @out_len: Length of Quote data, filled by VMM.
	* @data: Quote data on output or TDREPORT on input.
	*
	* More details of Quote request buffer can be found in TDX
	* Guest-Host Communication Interface (GHCI) for Intel TDX 1.0,
	* section titled "TDG.VP.VMCALL<GetQuote>"
	*/
	struct tdx_quote_buf {
	u64 version;
	u64 status;
	u32 in_len;
	u32 out_len;
	u8 data[];
	};

	/* Quote data buffer */
	static void *quote_data;

	/* Lock to streamline quote requests */
	static DEFINE_MUTEX(quote_lock);

	/*
	* GetQuote request timeout in seconds. Expect that 30 seconds
	* is enough time for QE to respond to any Quote requests.
	*/
	static u32 getquote_timeout = 30;

	static long tdx_get_report0(struct tdx_report_req __user *req)
	{
	u8 reportdata, tdreport;
	long ret;

	reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);
	if (!reportdata)
	return -ENOMEM;

	tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);
	if (!tdreport) {
	ret = -ENOMEM;
	goto out;
	}

	if (copy_from_user(reportdata, req->reportdata, TDX_REPORTDATA_LEN)) {
	ret = -EFAULT;
	goto out;
	}

	/* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */
	ret = tdx_mcall_get_report0(reportdata, tdreport);
	if (ret)
	goto out;

	if (copy_to_user(req->tdreport, tdreport, TDX_REPORT_LEN))
	ret = -EFAULT;

	out:
	kfree(reportdata);
	kfree(tdreport);

	return ret;
	}

	static void free_quote_buf(void *buf)
	{
	size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);
	unsigned int count = len >> PAGE_SHIFT;

	if (set_memory_encrypted((unsigned long)buf, count)) {
	pr_err("Failed to restore encryption mask for Quote buffer, leak it\n");
	return;
	}

	free_pages_exact(buf, len);
	}

	static void *alloc_quote_buf(void)
	{
	size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);
	unsigned int count = len >> PAGE_SHIFT;
	void *addr;

	addr = alloc_pages_exact(len, GFP_KERNEL \| __GFP_ZERO);
	if (!addr)
	return NULL;

	if (set_memory_decrypted((unsigned long)addr, count)) {
	free_pages_exact(addr, len);
	return NULL;
	}

	return addr;
	}

	/*
	* wait_for_quote_completion() - Wait for Quote request completion
	* @quote_buf: Address of Quote buffer.
	* @timeout: Timeout in seconds to wait for the Quote generation.
	*
	* As per TDX GHCI v1.0 specification, sec titled "TDG.VP.VMCALL<GetQuote>",
	* the status field in the Quote buffer will be set to GET_QUOTE_IN_FLIGHT
	* while VMM processes the GetQuote request, and will change it to success
	* or error code after processing is complete. So wait till the status
	* changes from GET_QUOTE_IN_FLIGHT or the request being timed out.
	*/
	static int wait_for_quote_completion(struct tdx_quote_buf *quote_buf, u32 timeout)
	{
	int i = 0;

	/*
	* Quote requests usually take a few seconds to complete, so waking up
	* once per second to recheck the status is fine for this use case.
	*/
	while (quote_buf->status == GET_QUOTE_IN_FLIGHT && i++ < timeout) {
	if (msleep_interruptible(MSEC_PER_SEC))
	return -EINTR;
	}

	return (i == timeout) ? -ETIMEDOUT : 0;
	}

	static int tdx_report_new(struct tsm_report report, void data)
	{
	u8 buf, reportdata = NULL, *tdreport = NULL;
	struct tdx_quote_buf *quote_buf = quote_data;
	struct tsm_desc *desc = &report->desc;
	int ret;
	u64 err;

	/* TODO: switch to guard(mutex_intr) */
	if (mutex_lock_interruptible(&quote_lock))
	return -EINTR;

	/*
	* If the previous request is timedout or interrupted, and the
	* Quote buf status is still in GET_QUOTE_IN_FLIGHT (owned by
	* VMM), don't permit any new request.
	*/
	if (quote_buf->status == GET_QUOTE_IN_FLIGHT) {
	ret = -EBUSY;
	goto done;
	}

	if (desc->inblob_len != TDX_REPORTDATA_LEN) {
	ret = -EINVAL;
	goto done;
	}

	reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);
	if (!reportdata) {
	ret = -ENOMEM;
	goto done;
	}

	tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);
	if (!tdreport) {
	ret = -ENOMEM;
	goto done;
	}

	memcpy(reportdata, desc->inblob, desc->inblob_len);

	/* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */
	ret = tdx_mcall_get_report0(reportdata, tdreport);
	if (ret) {
	pr_err("GetReport call failed\n");
	goto done;
	}

	memset(quote_data, 0, GET_QUOTE_BUF_SIZE);

	/* Update Quote buffer header */
	quote_buf->version = GET_QUOTE_CMD_VER;
	quote_buf->in_len = TDX_REPORT_LEN;

	memcpy(quote_buf->data, tdreport, TDX_REPORT_LEN);

	err = tdx_hcall_get_quote(quote_data, GET_QUOTE_BUF_SIZE);
	if (err) {
	pr_err("GetQuote hypercall failed, status:%llx\n", err);
	ret = -EIO;
	goto done;
	}

	ret = wait_for_quote_completion(quote_buf, getquote_timeout);
	if (ret) {
	pr_err("GetQuote request timedout\n");
	goto done;
	}

	buf = kvmemdup(quote_buf->data, quote_buf->out_len, GFP_KERNEL);
	if (!buf) {
	ret = -ENOMEM;
	goto done;
	}

	report->outblob = buf;
	report->outblob_len = quote_buf->out_len;

	/*
	* TODO: parse the PEM-formatted cert chain out of the quote buffer when
	* provided
	*/
	done:
	mutex_unlock(&quote_lock);
	kfree(reportdata);
	kfree(tdreport);

	return ret;
	}

	static long tdx_guest_ioctl(struct file *file, unsigned int cmd,
	unsigned long arg)
	{
	switch (cmd) {
	case TDX_CMD_GET_REPORT0:
	return tdx_get_report0((struct tdx_report_req __user *)arg);
	default:
	return -ENOTTY;
	}
	}

	static const struct file_operations tdx_guest_fops = {
	.owner = THIS_MODULE,
	.unlocked_ioctl = tdx_guest_ioctl,
	.llseek = no_llseek,
	};

	static struct miscdevice tdx_misc_dev = {
	.name = KBUILD_MODNAME,
	.minor = MISC_DYNAMIC_MINOR,
	.fops = &tdx_guest_fops,
	};

	static const struct x86_cpu_id tdx_guest_ids[] = {
	X86_MATCH_FEATURE(X86_FEATURE_TDX_GUEST, NULL),
	{}
	};
	MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids);

	static const struct tsm_ops tdx_tsm_ops = {
	.name = KBUILD_MODNAME,
	.report_new = tdx_report_new,
	};

	static int __init tdx_guest_init(void)
	{
	int ret;

	if (!x86_match_cpu(tdx_guest_ids))
	return -ENODEV;

	ret = misc_register(&tdx_misc_dev);
	if (ret)
	return ret;

	quote_data = alloc_quote_buf();
	if (!quote_data) {
	pr_err("Failed to allocate Quote buffer\n");
	ret = -ENOMEM;
	goto free_misc;
	}

	ret = tsm_register(&tdx_tsm_ops, NULL, NULL);
	if (ret)
	goto free_quote;

	return 0;

	free_quote:
	free_quote_buf(quote_data);
	free_misc:
	misc_deregister(&tdx_misc_dev);

	return ret;
	}
	module_init(tdx_guest_init);

	static void __exit tdx_guest_exit(void)
	{
	tsm_unregister(&tdx_tsm_ops);
	free_quote_buf(quote_data);
	misc_deregister(&tdx_misc_dev);
	}
	module_exit(tdx_guest_exit);

	MODULE_AUTHOR("Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>");
	MODULE_DESCRIPTION("TDX Guest Driver");
	MODULE_LICENSE("GPL");