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1// SPDX-License-Identifier: GPL-2.02/*3 * TDX guest user interface driver4 *5 * Copyright (C) 2022 Intel Corporation6 */7 8#include <linux/kernel.h>9#include <linux/miscdevice.h>10#include <linux/mm.h>11#include <linux/module.h>12#include <linux/mod_devicetable.h>13#include <linux/string.h>14#include <linux/uaccess.h>15#include <linux/set_memory.h>16#include <linux/io.h>17#include <linux/delay.h>18#include <linux/tsm.h>19#include <linux/sizes.h>20 21#include <uapi/linux/tdx-guest.h>22 23#include <asm/cpu_device_id.h>24#include <asm/tdx.h>25 26/*27 * Intel's SGX QE implementation generally uses Quote size less28 * than 8K (2K Quote data + ~5K of certificate blob).29 */30#define GET_QUOTE_BUF_SIZE SZ_8K31 32#define GET_QUOTE_CMD_VER 133 34/* TDX GetQuote status codes */35#define GET_QUOTE_SUCCESS 036#define GET_QUOTE_IN_FLIGHT 0xffffffffffffffff37 38/* struct tdx_quote_buf: Format of Quote request buffer.39 * @version: Quote format version, filled by TD.40 * @status: Status code of Quote request, filled by VMM.41 * @in_len: Length of TDREPORT, filled by TD.42 * @out_len: Length of Quote data, filled by VMM.43 * @data: Quote data on output or TDREPORT on input.44 *45 * More details of Quote request buffer can be found in TDX46 * Guest-Host Communication Interface (GHCI) for Intel TDX 1.0,47 * section titled "TDG.VP.VMCALL<GetQuote>"48 */49struct tdx_quote_buf {50 u64 version;51 u64 status;52 u32 in_len;53 u32 out_len;54 u8 data[];55};56 57/* Quote data buffer */58static void *quote_data;59 60/* Lock to streamline quote requests */61static DEFINE_MUTEX(quote_lock);62 63/*64 * GetQuote request timeout in seconds. Expect that 30 seconds65 * is enough time for QE to respond to any Quote requests.66 */67static u32 getquote_timeout = 30;68 69static long tdx_get_report0(struct tdx_report_req __user *req)70{71 u8 *reportdata, *tdreport;72 long ret;73 74 reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);75 if (!reportdata)76 return -ENOMEM;77 78 tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);79 if (!tdreport) {80 ret = -ENOMEM;81 goto out;82 }83 84 if (copy_from_user(reportdata, req->reportdata, TDX_REPORTDATA_LEN)) {85 ret = -EFAULT;86 goto out;87 }88 89 /* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */90 ret = tdx_mcall_get_report0(reportdata, tdreport);91 if (ret)92 goto out;93 94 if (copy_to_user(req->tdreport, tdreport, TDX_REPORT_LEN))95 ret = -EFAULT;96 97out:98 kfree(reportdata);99 kfree(tdreport);100 101 return ret;102}103 104static void free_quote_buf(void *buf)105{106 size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);107 unsigned int count = len >> PAGE_SHIFT;108 109 if (set_memory_encrypted((unsigned long)buf, count)) {110 pr_err("Failed to restore encryption mask for Quote buffer, leak it\n");111 return;112 }113 114 free_pages_exact(buf, len);115}116 117static void *alloc_quote_buf(void)118{119 size_t len = PAGE_ALIGN(GET_QUOTE_BUF_SIZE);120 unsigned int count = len >> PAGE_SHIFT;121 void *addr;122 123 addr = alloc_pages_exact(len, GFP_KERNEL | __GFP_ZERO);124 if (!addr)125 return NULL;126 127 if (set_memory_decrypted((unsigned long)addr, count)) {128 free_pages_exact(addr, len);129 return NULL;130 }131 132 return addr;133}134 135/*136 * wait_for_quote_completion() - Wait for Quote request completion137 * @quote_buf: Address of Quote buffer.138 * @timeout: Timeout in seconds to wait for the Quote generation.139 *140 * As per TDX GHCI v1.0 specification, sec titled "TDG.VP.VMCALL<GetQuote>",141 * the status field in the Quote buffer will be set to GET_QUOTE_IN_FLIGHT142 * while VMM processes the GetQuote request, and will change it to success143 * or error code after processing is complete. So wait till the status144 * changes from GET_QUOTE_IN_FLIGHT or the request being timed out.145 */146static int wait_for_quote_completion(struct tdx_quote_buf *quote_buf, u32 timeout)147{148 int i = 0;149 150 /*151 * Quote requests usually take a few seconds to complete, so waking up152 * once per second to recheck the status is fine for this use case.153 */154 while (quote_buf->status == GET_QUOTE_IN_FLIGHT && i++ < timeout) {155 if (msleep_interruptible(MSEC_PER_SEC))156 return -EINTR;157 }158 159 return (i == timeout) ? -ETIMEDOUT : 0;160}161 162static int tdx_report_new(struct tsm_report *report, void *data)163{164 u8 *buf, *reportdata = NULL, *tdreport = NULL;165 struct tdx_quote_buf *quote_buf = quote_data;166 struct tsm_desc *desc = &report->desc;167 int ret;168 u64 err;169 170 /* TODO: switch to guard(mutex_intr) */171 if (mutex_lock_interruptible("e_lock))172 return -EINTR;173 174 /*175 * If the previous request is timedout or interrupted, and the176 * Quote buf status is still in GET_QUOTE_IN_FLIGHT (owned by177 * VMM), don't permit any new request.178 */179 if (quote_buf->status == GET_QUOTE_IN_FLIGHT) {180 ret = -EBUSY;181 goto done;182 }183 184 if (desc->inblob_len != TDX_REPORTDATA_LEN) {185 ret = -EINVAL;186 goto done;187 }188 189 reportdata = kmalloc(TDX_REPORTDATA_LEN, GFP_KERNEL);190 if (!reportdata) {191 ret = -ENOMEM;192 goto done;193 }194 195 tdreport = kzalloc(TDX_REPORT_LEN, GFP_KERNEL);196 if (!tdreport) {197 ret = -ENOMEM;198 goto done;199 }200 201 memcpy(reportdata, desc->inblob, desc->inblob_len);202 203 /* Generate TDREPORT0 using "TDG.MR.REPORT" TDCALL */204 ret = tdx_mcall_get_report0(reportdata, tdreport);205 if (ret) {206 pr_err("GetReport call failed\n");207 goto done;208 }209 210 memset(quote_data, 0, GET_QUOTE_BUF_SIZE);211 212 /* Update Quote buffer header */213 quote_buf->version = GET_QUOTE_CMD_VER;214 quote_buf->in_len = TDX_REPORT_LEN;215 216 memcpy(quote_buf->data, tdreport, TDX_REPORT_LEN);217 218 err = tdx_hcall_get_quote(quote_data, GET_QUOTE_BUF_SIZE);219 if (err) {220 pr_err("GetQuote hypercall failed, status:%llx\n", err);221 ret = -EIO;222 goto done;223 }224 225 ret = wait_for_quote_completion(quote_buf, getquote_timeout);226 if (ret) {227 pr_err("GetQuote request timedout\n");228 goto done;229 }230 231 buf = kvmemdup(quote_buf->data, quote_buf->out_len, GFP_KERNEL);232 if (!buf) {233 ret = -ENOMEM;234 goto done;235 }236 237 report->outblob = buf;238 report->outblob_len = quote_buf->out_len;239 240 /*241 * TODO: parse the PEM-formatted cert chain out of the quote buffer when242 * provided243 */244done:245 mutex_unlock("e_lock);246 kfree(reportdata);247 kfree(tdreport);248 249 return ret;250}251 252static bool tdx_report_attr_visible(int n)253{254 switch (n) {255 case TSM_REPORT_GENERATION:256 case TSM_REPORT_PROVIDER:257 return true;258 }259 260 return false;261}262 263static bool tdx_report_bin_attr_visible(int n)264{265 switch (n) {266 case TSM_REPORT_INBLOB:267 case TSM_REPORT_OUTBLOB:268 return true;269 }270 271 return false;272}273 274static long tdx_guest_ioctl(struct file *file, unsigned int cmd,275 unsigned long arg)276{277 switch (cmd) {278 case TDX_CMD_GET_REPORT0:279 return tdx_get_report0((struct tdx_report_req __user *)arg);280 default:281 return -ENOTTY;282 }283}284 285static const struct file_operations tdx_guest_fops = {286 .owner = THIS_MODULE,287 .unlocked_ioctl = tdx_guest_ioctl,288};289 290static struct miscdevice tdx_misc_dev = {291 .name = KBUILD_MODNAME,292 .minor = MISC_DYNAMIC_MINOR,293 .fops = &tdx_guest_fops,294};295 296static const struct x86_cpu_id tdx_guest_ids[] = {297 X86_MATCH_FEATURE(X86_FEATURE_TDX_GUEST, NULL),298 {}299};300MODULE_DEVICE_TABLE(x86cpu, tdx_guest_ids);301 302static const struct tsm_ops tdx_tsm_ops = {303 .name = KBUILD_MODNAME,304 .report_new = tdx_report_new,305 .report_attr_visible = tdx_report_attr_visible,306 .report_bin_attr_visible = tdx_report_bin_attr_visible,307};308 309static int __init tdx_guest_init(void)310{311 int ret;312 313 if (!x86_match_cpu(tdx_guest_ids))314 return -ENODEV;315 316 ret = misc_register(&tdx_misc_dev);317 if (ret)318 return ret;319 320 quote_data = alloc_quote_buf();321 if (!quote_data) {322 pr_err("Failed to allocate Quote buffer\n");323 ret = -ENOMEM;324 goto free_misc;325 }326 327 ret = tsm_register(&tdx_tsm_ops, NULL);328 if (ret)329 goto free_quote;330 331 return 0;332 333free_quote:334 free_quote_buf(quote_data);335free_misc:336 misc_deregister(&tdx_misc_dev);337 338 return ret;339}340module_init(tdx_guest_init);341 342static void __exit tdx_guest_exit(void)343{344 tsm_unregister(&tdx_tsm_ops);345 free_quote_buf(quote_data);346 misc_deregister(&tdx_misc_dev);347}348module_exit(tdx_guest_exit);349 350MODULE_AUTHOR("Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>");351MODULE_DESCRIPTION("TDX Guest Driver");352MODULE_LICENSE("GPL");353