uvdevice.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  Copyright IBM Corp. 2022, 2024
  4 *  Author(s): Steffen Eiden <seiden@linux.ibm.com>
  5 *
  6 *  This file provides a Linux misc device to give userspace access to some
  7 *  Ultravisor (UV) functions. The device only accepts IOCTLs and will only
  8 *  be present if the Ultravisor facility (158) is present.
  9 *
 10 *  When userspace sends a valid IOCTL uvdevice will copy the input data to
 11 *  kernel space, do some basic validity checks to avoid kernel/system
 12 *  corruption. Any other check that the Ultravisor does will not be done by
 13 *  the uvdevice to keep changes minimal when adding new functionalities
 14 *  to existing UV-calls.
 15 *  After the checks uvdevice builds a corresponding
 16 *  Ultravisor Call Control Block, and sends the request to the Ultravisor.
 17 *  Then, it copies the response, including the return codes, back to userspace.
 18 *  It is the responsibility of the userspace to check for any error issued
 19 *  by UV and to interpret the UV response. The uvdevice acts as a communication
 20 *  channel for userspace to the Ultravisor.
 21 */
 22
 23#include <linux/module.h>
 24#include <linux/kernel.h>
 25#include <linux/miscdevice.h>
 26#include <linux/types.h>
 27#include <linux/stddef.h>
 28#include <linux/vmalloc.h>
 29#include <linux/slab.h>
 30#include <linux/cpufeature.h>
 31
 32#include <asm/uvdevice.h>
 33#include <asm/uv.h>
 34
 35#define BIT_UVIO_INTERNAL U32_MAX
 36/* Mapping from IOCTL-nr to UVC-bit */
 37static const u32 ioctl_nr_to_uvc_bit[] __initconst = {
 38	[UVIO_IOCTL_UVDEV_INFO_NR] = BIT_UVIO_INTERNAL,
 39	[UVIO_IOCTL_ATT_NR] = BIT_UVC_CMD_RETR_ATTEST,
 40	[UVIO_IOCTL_ADD_SECRET_NR] = BIT_UVC_CMD_ADD_SECRET,
 41	[UVIO_IOCTL_LIST_SECRETS_NR] = BIT_UVC_CMD_LIST_SECRETS,
 42	[UVIO_IOCTL_LOCK_SECRETS_NR] = BIT_UVC_CMD_LOCK_SECRETS,
 43	[UVIO_IOCTL_RETR_SECRET_NR] = BIT_UVC_CMD_RETR_ATTEST,
 44};
 45
 46static_assert(ARRAY_SIZE(ioctl_nr_to_uvc_bit) == UVIO_IOCTL_NUM_IOCTLS);
 47
 48static struct uvio_uvdev_info uvdev_info = {
 49	.supp_uvio_cmds = GENMASK_ULL(UVIO_IOCTL_NUM_IOCTLS - 1, 0),
 50};
 51
 52static void __init set_supp_uv_cmds(unsigned long *supp_uv_cmds)
 53{
 54	int i;
 55
 56	for (i = 0; i < UVIO_IOCTL_NUM_IOCTLS; i++) {
 57		if (ioctl_nr_to_uvc_bit[i] == BIT_UVIO_INTERNAL)
 58			continue;
 59		if (!test_bit_inv(ioctl_nr_to_uvc_bit[i], uv_info.inst_calls_list))
 60			continue;
 61		__set_bit(i, supp_uv_cmds);
 62	}
 63}
 64
 65/**
 66 * uvio_uvdev_info() - Get information about the uvdevice
 67 *
 68 * @uv_ioctl: ioctl control block
 69 *
 70 * Lists all IOCTLs that are supported by this uvdevice
 71 *
 72 * Return: 0 on success or a negative error code on error
 73 */
 74static int uvio_uvdev_info(struct uvio_ioctl_cb *uv_ioctl)
 75{
 76	void __user *user_buf_arg = (void __user *)uv_ioctl->argument_addr;
 77
 78	if (uv_ioctl->argument_len < sizeof(uvdev_info))
 79		return -EINVAL;
 80	if (copy_to_user(user_buf_arg, &uvdev_info, sizeof(uvdev_info)))
 81		return -EFAULT;
 82
 83	uv_ioctl->uv_rc = UVC_RC_EXECUTED;
 84	return 0;
 85}
 86
 87static int uvio_build_uvcb_attest(struct uv_cb_attest *uvcb_attest, u8 *arcb,
 88				  u8 *meas, u8 *add_data, struct uvio_attest *uvio_attest)
 89{
 90	void __user *user_buf_arcb = (void __user *)uvio_attest->arcb_addr;
 91
 92	if (copy_from_user(arcb, user_buf_arcb, uvio_attest->arcb_len))
 93		return -EFAULT;
 94
 95	uvcb_attest->header.len = sizeof(*uvcb_attest);
 96	uvcb_attest->header.cmd = UVC_CMD_RETR_ATTEST;
 97	uvcb_attest->arcb_addr = (u64)arcb;
 98	uvcb_attest->cont_token = 0;
 99	uvcb_attest->user_data_len = uvio_attest->user_data_len;
100	memcpy(uvcb_attest->user_data, uvio_attest->user_data, sizeof(uvcb_attest->user_data));
101	uvcb_attest->meas_len = uvio_attest->meas_len;
102	uvcb_attest->meas_addr = (u64)meas;
103	uvcb_attest->add_data_len = uvio_attest->add_data_len;
104	uvcb_attest->add_data_addr = (u64)add_data;
105
106	return 0;
107}
108
109static int uvio_copy_attest_result_to_user(struct uv_cb_attest *uvcb_attest,
110					   struct uvio_ioctl_cb *uv_ioctl,
111					   u8 *measurement, u8 *add_data,
112					   struct uvio_attest *uvio_attest)
113{
114	struct uvio_attest __user *user_uvio_attest = (void __user *)uv_ioctl->argument_addr;
115	u32 __user *user_buf_add_len = (u32 __user *)&user_uvio_attest->add_data_len;
116	void __user *user_buf_add = (void __user *)uvio_attest->add_data_addr;
117	void __user *user_buf_meas = (void __user *)uvio_attest->meas_addr;
118	void __user *user_buf_uid = &user_uvio_attest->config_uid;
119
120	if (copy_to_user(user_buf_meas, measurement, uvio_attest->meas_len))
121		return -EFAULT;
122	if (add_data && copy_to_user(user_buf_add, add_data, uvio_attest->add_data_len))
123		return -EFAULT;
124	if (put_user(uvio_attest->add_data_len, user_buf_add_len))
125		return -EFAULT;
126	if (copy_to_user(user_buf_uid, uvcb_attest->config_uid, sizeof(uvcb_attest->config_uid)))
127		return -EFAULT;
128	return 0;
129}
130
131static int get_uvio_attest(struct uvio_ioctl_cb *uv_ioctl, struct uvio_attest *uvio_attest)
132{
133	u8 __user *user_arg_buf = (u8 __user *)uv_ioctl->argument_addr;
134
135	if (copy_from_user(uvio_attest, user_arg_buf, sizeof(*uvio_attest)))
136		return -EFAULT;
137
138	if (uvio_attest->arcb_len > UVIO_ATT_ARCB_MAX_LEN)
139		return -EINVAL;
140	if (uvio_attest->arcb_len == 0)
141		return -EINVAL;
142	if (uvio_attest->meas_len > UVIO_ATT_MEASUREMENT_MAX_LEN)
143		return -EINVAL;
144	if (uvio_attest->meas_len == 0)
145		return -EINVAL;
146	if (uvio_attest->add_data_len > UVIO_ATT_ADDITIONAL_MAX_LEN)
147		return -EINVAL;
148	if (uvio_attest->reserved136)
149		return -EINVAL;
150	return 0;
151}
152
153/**
154 * uvio_attestation() - Perform a Retrieve Attestation Measurement UVC.
155 *
156 * @uv_ioctl: ioctl control block
157 *
158 * uvio_attestation() does a Retrieve Attestation Measurement Ultravisor Call.
159 * It verifies that the given userspace addresses are valid and request sizes
160 * are sane. Every other check is made by the Ultravisor (UV) and won't result
161 * in a negative return value. It copies the input to kernelspace, builds the
162 * request, sends the UV-call, and copies the result to userspace.
163 *
164 * The Attestation Request has two input and two outputs.
165 * ARCB and User Data are inputs for the UV generated by userspace.
166 * Measurement and Additional Data are outputs for userspace generated by UV.
167 *
168 * The Attestation Request Control Block (ARCB) is a cryptographically verified
169 * and secured request to UV and User Data is some plaintext data which is
170 * going to be included in the Attestation Measurement calculation.
171 *
172 * Measurement is a cryptographic measurement of the callers properties,
173 * optional data configured by the ARCB and the user data. If specified by the
174 * ARCB, UV will add some Additional Data to the measurement calculation.
175 * This Additional Data is then returned as well.
176 *
177 * If the Retrieve Attestation Measurement UV facility is not present,
178 * UV will return invalid command rc. This won't be fenced in the driver
179 * and does not result in a negative return value.
180 *
181 * Context: might sleep
182 *
183 * Return: 0 on success or a negative error code on error
184 */
185static int uvio_attestation(struct uvio_ioctl_cb *uv_ioctl)
186{
187	struct uv_cb_attest *uvcb_attest = NULL;
188	struct uvio_attest *uvio_attest = NULL;
189	u8 *measurement = NULL;
190	u8 *add_data = NULL;
191	u8 *arcb = NULL;
192	int ret;
193
194	ret = -EINVAL;
195	if (uv_ioctl->argument_len != sizeof(*uvio_attest))
196		goto out;
197
198	ret = -ENOMEM;
199	uvio_attest = kzalloc(sizeof(*uvio_attest), GFP_KERNEL);
200	if (!uvio_attest)
201		goto out;
202
203	ret = get_uvio_attest(uv_ioctl, uvio_attest);
204	if (ret)
205		goto out;
206
207	ret = -ENOMEM;
208	arcb = kvzalloc(uvio_attest->arcb_len, GFP_KERNEL);
209	measurement = kvzalloc(uvio_attest->meas_len, GFP_KERNEL);
210	if (!arcb || !measurement)
211		goto out;
212
213	if (uvio_attest->add_data_len) {
214		add_data = kvzalloc(uvio_attest->add_data_len, GFP_KERNEL);
215		if (!add_data)
216			goto out;
217	}
218
219	uvcb_attest = kzalloc(sizeof(*uvcb_attest), GFP_KERNEL);
220	if (!uvcb_attest)
221		goto out;
222
223	ret = uvio_build_uvcb_attest(uvcb_attest, arcb,  measurement, add_data, uvio_attest);
224	if (ret)
225		goto out;
226
227	uv_call_sched(0, (u64)uvcb_attest);
228
229	uv_ioctl->uv_rc = uvcb_attest->header.rc;
230	uv_ioctl->uv_rrc = uvcb_attest->header.rrc;
231
232	ret = uvio_copy_attest_result_to_user(uvcb_attest, uv_ioctl, measurement, add_data,
233					      uvio_attest);
234out:
235	kvfree(arcb);
236	kvfree(measurement);
237	kvfree(add_data);
238	kfree(uvio_attest);
239	kfree(uvcb_attest);
240	return ret;
241}
242
243/**
244 * uvio_add_secret() - Perform an Add Secret UVC
245 *
246 * @uv_ioctl: ioctl control block
247 *
248 * uvio_add_secret() performs the Add Secret Ultravisor Call.
249 *
250 * The given userspace argument address and size are verified to be
251 * valid but every other check is made by the Ultravisor
252 * (UV). Therefore UV errors won't result in a negative return
253 * value. The request is then copied to kernelspace, the UV-call is
254 * performed and the results are copied back to userspace.
255 *
256 * The argument has to point to an Add Secret Request Control Block
257 * which is an encrypted and cryptographically verified request that
258 * inserts a protected guest's secrets into the Ultravisor for later
259 * use.
260 *
261 * If the Add Secret UV facility is not present, UV will return
262 * invalid command rc. This won't be fenced in the driver and does not
263 * result in a negative return value.
264 *
265 * Context: might sleep
266 *
267 * Return: 0 on success or a negative error code on error
268 */
269static int uvio_add_secret(struct uvio_ioctl_cb *uv_ioctl)
270{
271	void __user *user_buf_arg = (void __user *)uv_ioctl->argument_addr;
272	struct uv_cb_guest_addr uvcb = {
273		.header.len = sizeof(uvcb),
274		.header.cmd = UVC_CMD_ADD_SECRET,
275	};
276	void *asrcb = NULL;
277	int ret;
278
279	if (uv_ioctl->argument_len > UVIO_ADD_SECRET_MAX_LEN)
280		return -EINVAL;
281	if (uv_ioctl->argument_len == 0)
282		return -EINVAL;
283
284	asrcb = kvzalloc(uv_ioctl->argument_len, GFP_KERNEL);
285	if (!asrcb)
286		return -ENOMEM;
287
288	ret = -EFAULT;
289	if (copy_from_user(asrcb, user_buf_arg, uv_ioctl->argument_len))
290		goto out;
291
292	ret = 0;
293	uvcb.addr = (u64)asrcb;
294	uv_call_sched(0, (u64)&uvcb);
295	uv_ioctl->uv_rc = uvcb.header.rc;
296	uv_ioctl->uv_rrc = uvcb.header.rrc;
297
298out:
299	kvfree(asrcb);
300	return ret;
301}
302
303/*
304 * Do the actual secret list creation. Calls the list secrets UVC until there
305 * is no more space in the user buffer, or the list ends.
306 */
307static int uvio_get_list(void *zpage, struct uvio_ioctl_cb *uv_ioctl)
308{
309	const size_t data_off = offsetof(struct uv_secret_list, secrets);
310	u8 __user *user_buf = (u8 __user *)uv_ioctl->argument_addr;
311	struct uv_secret_list *list = zpage;
312	u16 num_secrets_stored = 0;
313	size_t user_off = data_off;
314	size_t copy_len;
315
316	do {
317		uv_list_secrets(list, list->next_secret_idx, &uv_ioctl->uv_rc,
318				&uv_ioctl->uv_rrc);
319		if (uv_ioctl->uv_rc != UVC_RC_EXECUTED &&
320		    uv_ioctl->uv_rc != UVC_RC_MORE_DATA)
321			break;
322
323		copy_len = sizeof(list->secrets[0]) * list->num_secr_stored;
324		if (copy_to_user(user_buf + user_off, list->secrets, copy_len))
325			return -EFAULT;
326
327		user_off += copy_len;
328		num_secrets_stored += list->num_secr_stored;
329	} while (uv_ioctl->uv_rc == UVC_RC_MORE_DATA &&
330		 user_off + sizeof(*list) <= uv_ioctl->argument_len);
331
332	list->num_secr_stored = num_secrets_stored;
333	if (copy_to_user(user_buf, list, data_off))
334		return -EFAULT;
335	return 0;
336}
337
338/**
339 * uvio_list_secrets() - Perform a List Secret UVC
340 *
341 * @uv_ioctl: ioctl control block
342 *
343 * uvio_list_secrets() performs the List Secret Ultravisor Call. It verifies
344 * that the given userspace argument address is valid and its size is sane.
345 * Every other check is made by the Ultravisor (UV) and won't result in a
346 * negative return value. It builds the request, performs the UV-call, and
347 * copies the result to userspace.
348 *
349 * The argument specifies the location for the result of the UV-Call.
350 *
351 * Argument length must be a multiple of a page.
352 * The list secrets IOCTL will call the list UVC multiple times and fill
353 * the provided user-buffer with list elements until either the list ends or
354 * the buffer is full. The list header is merged over all list header from the
355 * individual UVCs.
356 *
357 * If the List Secrets UV facility is not present, UV will return invalid
358 * command rc. This won't be fenced in the driver and does not result in a
359 * negative return value.
360 *
361 * Context: might sleep
362 *
363 * Return: 0 on success or a negative error code on error
364 */
365static int uvio_list_secrets(struct uvio_ioctl_cb *uv_ioctl)
366{
367	void *zpage;
368	int rc;
369
370	if (uv_ioctl->argument_len == 0 ||
371	    uv_ioctl->argument_len % UVIO_LIST_SECRETS_LEN != 0)
372		return -EINVAL;
373
374	zpage = (void *)get_zeroed_page(GFP_KERNEL);
375	if (!zpage)
376		return -ENOMEM;
377
378	rc = uvio_get_list(zpage, uv_ioctl);
379
380	free_page((unsigned long)zpage);
381	return rc;
382}
383
384/**
385 * uvio_lock_secrets() - Perform a Lock Secret Store UVC
386 *
387 * @ioctl: ioctl control block
388 *
389 * uvio_lock_secrets() performs the Lock Secret Store Ultravisor Call. It
390 * performs the UV-call and copies the return codes to the ioctl control block.
391 * After this call was dispatched successfully every following Add Secret UVC
392 * and Lock Secrets UVC will fail with return code 0x102.
393 *
394 * The argument address and size must be 0.
395 *
396 * If the Lock Secrets UV facility is not present, UV will return invalid
397 * command rc. This won't be fenced in the driver and does not result in a
398 * negative return value.
399 *
400 * Context: might sleep
401 *
402 * Return: 0 on success or a negative error code on error
403 */
404static int uvio_lock_secrets(struct uvio_ioctl_cb *ioctl)
405{
406	struct uv_cb_nodata uvcb = {
407		.header.len = sizeof(uvcb),
408		.header.cmd = UVC_CMD_LOCK_SECRETS,
409	};
410
411	if (ioctl->argument_addr || ioctl->argument_len)
412		return -EINVAL;
413
414	uv_call(0, (u64)&uvcb);
415	ioctl->uv_rc = uvcb.header.rc;
416	ioctl->uv_rrc = uvcb.header.rrc;
417
418	return 0;
419}
420
421/**
422 * uvio_retr_secret() - Perform a retrieve secret UVC
423 *
424 * @uv_ioctl: ioctl control block.
425 *
426 * uvio_retr_secret() performs the Retrieve Secret Ultravisor Call.
427 * The first two bytes of the argument specify the index of the secret to be
428 * retrieved. The retrieved secret is copied into the argument buffer if there
429 * is enough space.
430 * The argument length must be at least two bytes and at max 8192 bytes.
431 *
432 * Context: might sleep
433 *
434 * Return: 0 on success or a negative error code on error
435 */
436static int uvio_retr_secret(struct uvio_ioctl_cb *uv_ioctl)
437{
438	u16 __user *user_index = (u16 __user *)uv_ioctl->argument_addr;
439	struct uv_cb_retr_secr uvcb = {
440		.header.len = sizeof(uvcb),
441		.header.cmd = UVC_CMD_RETR_SECRET,
442	};
443	u32 buf_len = uv_ioctl->argument_len;
444	void *buf = NULL;
445	int ret;
446
447	if (buf_len > UVIO_RETR_SECRET_MAX_LEN || buf_len < sizeof(*user_index))
448		return -EINVAL;
449
450	buf = kvzalloc(buf_len, GFP_KERNEL);
451	if (!buf)
452		return -ENOMEM;
453
454	ret = -EFAULT;
455	if (get_user(uvcb.secret_idx, user_index))
456		goto err;
457
458	uvcb.buf_addr = (u64)buf;
459	uvcb.buf_size = buf_len;
460	uv_call_sched(0, (u64)&uvcb);
461
462	if (copy_to_user((__user void *)uv_ioctl->argument_addr, buf, buf_len))
463		goto err;
464
465	ret = 0;
466	uv_ioctl->uv_rc = uvcb.header.rc;
467	uv_ioctl->uv_rrc = uvcb.header.rrc;
468
469err:
470	kvfree_sensitive(buf, buf_len);
471	return ret;
472}
473
474static int uvio_copy_and_check_ioctl(struct uvio_ioctl_cb *ioctl, void __user *argp,
475				     unsigned long cmd)
476{
477	u8 nr = _IOC_NR(cmd);
478
479	if (_IOC_DIR(cmd) != (_IOC_READ | _IOC_WRITE))
480		return -ENOIOCTLCMD;
481	if (_IOC_TYPE(cmd) != UVIO_TYPE_UVC)
482		return -ENOIOCTLCMD;
483	if (nr >= UVIO_IOCTL_NUM_IOCTLS)
484		return -ENOIOCTLCMD;
485	if (_IOC_SIZE(cmd) != sizeof(*ioctl))
486		return -ENOIOCTLCMD;
487	if (copy_from_user(ioctl, argp, sizeof(*ioctl)))
488		return -EFAULT;
489	if (ioctl->flags != 0)
490		return -EINVAL;
491	if (memchr_inv(ioctl->reserved14, 0, sizeof(ioctl->reserved14)))
492		return -EINVAL;
493
494	return nr;
495}
496
497/*
498 * IOCTL entry point for the Ultravisor device.
499 */
500static long uvio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
501{
502	void __user *argp = (void __user *)arg;
503	struct uvio_ioctl_cb uv_ioctl = { };
504	long ret;
505	int nr;
506
507	nr = uvio_copy_and_check_ioctl(&uv_ioctl, argp, cmd);
508	if (nr < 0)
509		return nr;
510
511	switch (nr) {
512	case UVIO_IOCTL_UVDEV_INFO_NR:
513		ret = uvio_uvdev_info(&uv_ioctl);
514		break;
515	case UVIO_IOCTL_ATT_NR:
516		ret = uvio_attestation(&uv_ioctl);
517		break;
518	case UVIO_IOCTL_ADD_SECRET_NR:
519		ret = uvio_add_secret(&uv_ioctl);
520		break;
521	case UVIO_IOCTL_LIST_SECRETS_NR:
522		ret = uvio_list_secrets(&uv_ioctl);
523		break;
524	case UVIO_IOCTL_LOCK_SECRETS_NR:
525		ret = uvio_lock_secrets(&uv_ioctl);
526		break;
527	case UVIO_IOCTL_RETR_SECRET_NR:
528		ret = uvio_retr_secret(&uv_ioctl);
529		break;
530	default:
531		ret = -ENOIOCTLCMD;
532		break;
533	}
534	if (ret)
535		return ret;
536
537	if (copy_to_user(argp, &uv_ioctl, sizeof(uv_ioctl)))
538		ret = -EFAULT;
539
540	return ret;
541}
542
543static const struct file_operations uvio_dev_fops = {
544	.owner = THIS_MODULE,
545	.unlocked_ioctl = uvio_ioctl,
546};
547
548static struct miscdevice uvio_dev_miscdev = {
549	.minor = MISC_DYNAMIC_MINOR,
550	.name = UVIO_DEVICE_NAME,
551	.fops = &uvio_dev_fops,
552};
553
554static void __exit uvio_dev_exit(void)
555{
556	misc_deregister(&uvio_dev_miscdev);
557}
558
559static int __init uvio_dev_init(void)
560{
561	set_supp_uv_cmds((unsigned long *)&uvdev_info.supp_uv_cmds);
562	return misc_register(&uvio_dev_miscdev);
563}
564
565module_cpu_feature_match(S390_CPU_FEATURE_UV, uvio_dev_init);
566module_exit(uvio_dev_exit);
567
568MODULE_AUTHOR("IBM Corporation");
569MODULE_LICENSE("GPL");
570MODULE_DESCRIPTION("Ultravisor UAPI driver");