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2023-12-09 b22da3d8526a935aa31e086e63f60ff3246cb61c 
 kernel/arch/arm64/include/asm/uaccess.h
....@@ -1,19 +1,8 @@
1
+/* SPDX-License-Identifier: GPL-2.0-only */
12 /*
23  * Based on arch/arm/include/asm/uaccess.h
34  *
45  * Copyright (C) 2012 ARM Ltd.
5
- *
6
- * This program is free software; you can redistribute it and/or modify
7
- * it under the terms of the GNU General Public License version 2 as
8
- * published by the Free Software Foundation.
9
- *
10
- * This program is distributed in the hope that it will be useful,
11
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
12
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13
- * GNU General Public License for more details.
14
- *
15
- * You should have received a copy of the GNU General Public License
16
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
176  */
187 #ifndef __ASM_UACCESS_H
198 #define __ASM_UACCESS_H
....@@ -30,12 +19,14 @@
3019 #include <linux/string.h>
3120 
3221 #include <asm/cpufeature.h>
22
+#include <asm/mmu.h>
23
+#include <asm/mte.h>
3324 #include <asm/ptrace.h>
3425 #include <asm/memory.h>
35
-#include <asm/compiler.h>
3626 #include <asm/extable.h>
3727 
38
-#define get_ds()	(KERNEL_DS)
28
+#define HAVE_GET_KERNEL_NOFAULT
29
+
3930 #define get_fs()	(current_thread_info()->addr_limit)
4031 
4132 static inline void set_fs(mm_segment_t fs)
....@@ -46,8 +37,7 @@
4637 	 * Prevent a mispredicted conditional call to set_fs from forwarding
4738 	 * the wrong address limit to access_ok under speculation.
4839 	 */
49
-	dsb(nsh);
50
-	isb();
40
+	spec_bar();
5141 
5242 	/* On user-mode return, check fs is correct */
5343 	set_thread_flag(TIF_FSCHECK);
....@@ -63,7 +53,7 @@
6353 				CONFIG_ARM64_UAO));
6454 }
6555 
66
-#define segment_eq(a, b)	((a) == (b))
56
+#define uaccess_kernel()	(get_fs() == KERNEL_DS)
6757 
6858 /*
6959  * Test whether a block of memory is a valid user space address.
....@@ -106,7 +96,7 @@
10696 	return ret;
10797 }
10898 
109
-#define access_ok(type, addr, size)	__range_ok(addr, size)
99
+#define access_ok(addr, size)	__range_ok(addr, size)
110100 #define user_addr_max			get_fs
111101 
112102 #define _ASM_EXTABLE(from, to)						\
....@@ -126,8 +116,8 @@
126116 	local_irq_save(flags);
127117 	ttbr = read_sysreg(ttbr1_el1);
128118 	ttbr &= ~TTBR_ASID_MASK;
129
-	/* reserved_ttbr0 placed before swapper_pg_dir */
130
-	write_sysreg(ttbr - RESERVED_TTBR0_SIZE, ttbr0_el1);
119
+	/* reserved_pg_dir placed before swapper_pg_dir */
120
+	write_sysreg(ttbr - PAGE_SIZE, ttbr0_el1);
131121 	isb();
132122 	/* Set reserved ASID */
133123 	write_sysreg(ttbr, ttbr1_el1);
....@@ -213,13 +203,63 @@
213203 				CONFIG_ARM64_PAN));			\
214204 } while (0)
215205 
216
-static inline void uaccess_disable(void)
206
+/*
207
+ * The Tag Check Flag (TCF) mode for MTE is per EL, hence TCF0
208
+ * affects EL0 and TCF affects EL1 irrespective of which TTBR is
209
+ * used.
210
+ * The kernel accesses TTBR0 usually with LDTR/STTR instructions
211
+ * when UAO is available, so these would act as EL0 accesses using
212
+ * TCF0.
213
+ * However futex.h code uses exclusives which would be executed as
214
+ * EL1, this can potentially cause a tag check fault even if the
215
+ * user disables TCF0.
216
+ *
217
+ * To address the problem we set the PSTATE.TCO bit in uaccess_enable()
218
+ * and reset it in uaccess_disable().
219
+ *
220
+ * The Tag check override (TCO) bit disables temporarily the tag checking
221
+ * preventing the issue.
222
+ */
223
+static inline void __uaccess_disable_tco(void)
217224 {
225
+	asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(0),
226
+				 ARM64_MTE, CONFIG_KASAN_HW_TAGS));
227
+}
228
+
229
+static inline void __uaccess_enable_tco(void)
230
+{
231
+	asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(1),
232
+				 ARM64_MTE, CONFIG_KASAN_HW_TAGS));
233
+}
234
+
235
+/*
236
+ * These functions disable tag checking only if in MTE async mode
237
+ * since the sync mode generates exceptions synchronously and the
238
+ * nofault or load_unaligned_zeropad can handle them.
239
+ */
240
+static inline void __uaccess_disable_tco_async(void)
241
+{
242
+	if (system_uses_mte_async_mode())
243
+		 __uaccess_disable_tco();
244
+}
245
+
246
+static inline void __uaccess_enable_tco_async(void)
247
+{
248
+	if (system_uses_mte_async_mode())
249
+		__uaccess_enable_tco();
250
+}
251
+
252
+static inline void uaccess_disable_privileged(void)
253
+{
254
+	__uaccess_disable_tco();
255
+
218256 	__uaccess_disable(ARM64_HAS_PAN);
219257 }
220258 
221
-static inline void uaccess_enable(void)
259
+static inline void uaccess_enable_privileged(void)
222260 {
261
+	__uaccess_enable_tco();
262
+
223263 	__uaccess_enable(ARM64_HAS_PAN);
224264 }
225265 
....@@ -266,10 +306,9 @@
266306  * The "__xxx_error" versions set the third argument to -EFAULT if an error
267307  * occurs, and leave it unchanged on success.
268308  */
269
-#define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature)	\
309
+#define __get_mem_asm(load, reg, x, addr, err)				\
270310 	asm volatile(							\
271
-	"1:"ALTERNATIVE(instr "     " reg "1, [%2]\n",			\
272
-			alt_instr " " reg "1, [%2]\n", feature)		\
311
+	"1:	" load "	" reg "1, [%2]\n"			\
273312 	"2:\n"								\
274313 	"	.section .fixup, \"ax\"\n"				\
275314 	"	.align	2\n"						\
....@@ -281,66 +320,90 @@
281320 	: "+r" (err), "=&r" (x)						\
282321 	: "r" (addr), "i" (-EFAULT))
283322 
284
-#define __get_user_err(x, ptr, err)					\
323
+#define __raw_get_mem(ldr, x, ptr, err)					\
285324 do {									\
286325 	unsigned long __gu_val;						\
287
-	__chk_user_ptr(ptr);						\
288
-	uaccess_enable_not_uao();					\
289326 	switch (sizeof(*(ptr))) {					\
290327 	case 1:								\
291
-		__get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr),  \
292
-			       (err), ARM64_HAS_UAO);			\
328
+		__get_mem_asm(ldr "b", "%w", __gu_val, (ptr), (err));	\
293329 		break;							\
294330 	case 2:								\
295
-		__get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr),  \
296
-			       (err), ARM64_HAS_UAO);			\
331
+		__get_mem_asm(ldr "h", "%w", __gu_val, (ptr), (err));	\
297332 		break;							\
298333 	case 4:								\
299
-		__get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr),	\
300
-			       (err), ARM64_HAS_UAO);			\
334
+		__get_mem_asm(ldr, "%w", __gu_val, (ptr), (err));	\
301335 		break;							\
302336 	case 8:								\
303
-		__get_user_asm("ldr", "ldtr", "%x",  __gu_val, (ptr),	\
304
-			       (err), ARM64_HAS_UAO);			\
337
+		__get_mem_asm(ldr, "%x",  __gu_val, (ptr), (err));	\
305338 		break;							\
306339 	default:							\
307340 		BUILD_BUG();						\
308341 	}								\
309
-	uaccess_disable_not_uao();					\
310342 	(x) = (__force __typeof__(*(ptr)))__gu_val;			\
311343 } while (0)
312344 
313
-#define __get_user_check(x, ptr, err)					\
314
-({									\
315
-	__typeof__(*(ptr)) __user *__p = (ptr);				\
316
-	might_fault();							\
317
-	if (access_ok(VERIFY_READ, __p, sizeof(*__p))) {		\
318
-		__p = uaccess_mask_ptr(__p);				\
319
-		__get_user_err((x), __p, (err));			\
320
-	} else {							\
321
-		(x) = 0; (err) = -EFAULT;				\
322
-	}								\
323
-})
345
+/*
346
+ * We must not call into the scheduler between uaccess_enable_not_uao() and
347
+ * uaccess_disable_not_uao(). As `x` and `ptr` could contain blocking functions,
348
+ * we must evaluate these outside of the critical section.
349
+ */
350
+#define __raw_get_user(x, ptr, err)					\
351
+do {									\
352
+	__typeof__(*(ptr)) __user *__rgu_ptr = (ptr);			\
353
+	__typeof__(x) __rgu_val;					\
354
+	__chk_user_ptr(ptr);						\
355
+									\
356
+	uaccess_enable_not_uao();					\
357
+	__raw_get_mem("ldtr", __rgu_val, __rgu_ptr, err);		\
358
+	uaccess_disable_not_uao();					\
359
+									\
360
+	(x) = __rgu_val;						\
361
+} while (0)
324362 
325363 #define __get_user_error(x, ptr, err)					\
326
-({									\
327
-	__get_user_check((x), (ptr), (err));				\
328
-	(void)0;							\
329
-})
364
+do {									\
365
+	__typeof__(*(ptr)) __user *__p = (ptr);				\
366
+	might_fault();							\
367
+	if (access_ok(__p, sizeof(*__p))) {				\
368
+		__p = uaccess_mask_ptr(__p);				\
369
+		__raw_get_user((x), __p, (err));			\
370
+	} else {							\
371
+		(x) = (__force __typeof__(x))0; (err) = -EFAULT;	\
372
+	}								\
373
+} while (0)
330374 
331375 #define __get_user(x, ptr)						\
332376 ({									\
333377 	int __gu_err = 0;						\
334
-	__get_user_check((x), (ptr), __gu_err);				\
378
+	__get_user_error((x), (ptr), __gu_err);				\
335379 	__gu_err;							\
336380 })
337381 
338382 #define get_user	__get_user
339383 
340
-#define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature)	\
384
+/*
385
+ * We must not call into the scheduler between __uaccess_enable_tco_async() and
386
+ * __uaccess_disable_tco_async(). As `dst` and `src` may contain blocking
387
+ * functions, we must evaluate these outside of the critical section.
388
+ */
389
+#define __get_kernel_nofault(dst, src, type, err_label)			\
390
+do {									\
391
+	__typeof__(dst) __gkn_dst = (dst);				\
392
+	__typeof__(src) __gkn_src = (src);				\
393
+	int __gkn_err = 0;						\
394
+									\
395
+	__uaccess_enable_tco_async();					\
396
+	__raw_get_mem("ldr", *((type *)(__gkn_dst)),			\
397
+		      (__force type *)(__gkn_src), __gkn_err);		\
398
+	__uaccess_disable_tco_async();					\
399
+									\
400
+	if (unlikely(__gkn_err))					\
401
+		goto err_label;						\
402
+} while (0)
403
+
404
+#define __put_mem_asm(store, reg, x, addr, err)				\
341405 	asm volatile(							\
342
-	"1:"ALTERNATIVE(instr "     " reg "1, [%2]\n",			\
343
-			alt_instr " " reg "1, [%2]\n", feature)		\
406
+	"1:	" store "	" reg "1, [%2]\n"			\
344407 	"2:\n"								\
345408 	"	.section .fixup,\"ax\"\n"				\
346409 	"	.align	2\n"						\
....@@ -351,78 +414,115 @@
351414 	: "+r" (err)							\
352415 	: "r" (x), "r" (addr), "i" (-EFAULT))
353416 
354
-#define __put_user_err(x, ptr, err)					\
417
+#define __raw_put_mem(str, x, ptr, err)					\
355418 do {									\
356419 	__typeof__(*(ptr)) __pu_val = (x);				\
357
-	__chk_user_ptr(ptr);						\
358
-	uaccess_enable_not_uao();					\
359420 	switch (sizeof(*(ptr))) {					\
360421 	case 1:								\
361
-		__put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr),	\
362
-			       (err), ARM64_HAS_UAO);			\
422
+		__put_mem_asm(str "b", "%w", __pu_val, (ptr), (err));	\
363423 		break;							\
364424 	case 2:								\
365
-		__put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr),	\
366
-			       (err), ARM64_HAS_UAO);			\
425
+		__put_mem_asm(str "h", "%w", __pu_val, (ptr), (err));	\
367426 		break;							\
368427 	case 4:								\
369
-		__put_user_asm("str", "sttr", "%w", __pu_val, (ptr),	\
370
-			       (err), ARM64_HAS_UAO);			\
428
+		__put_mem_asm(str, "%w", __pu_val, (ptr), (err));	\
371429 		break;							\
372430 	case 8:								\
373
-		__put_user_asm("str", "sttr", "%x", __pu_val, (ptr),	\
374
-			       (err), ARM64_HAS_UAO);			\
431
+		__put_mem_asm(str, "%x", __pu_val, (ptr), (err));	\
375432 		break;							\
376433 	default:							\
377434 		BUILD_BUG();						\
378435 	}								\
436
+} while (0)
437
+
438
+/*
439
+ * We must not call into the scheduler between uaccess_enable_not_uao() and
440
+ * uaccess_disable_not_uao(). As `x` and `ptr` could contain blocking functions,
441
+ * we must evaluate these outside of the critical section.
442
+ */
443
+#define __raw_put_user(x, ptr, err)					\
444
+do {									\
445
+	__typeof__(*(ptr)) __user *__rpu_ptr = (ptr);			\
446
+	__typeof__(*(ptr)) __rpu_val = (x);				\
447
+	__chk_user_ptr(__rpu_ptr);					\
448
+									\
449
+	uaccess_enable_not_uao();					\
450
+	__raw_put_mem("sttr", __rpu_val, __rpu_ptr, err);		\
379451 	uaccess_disable_not_uao();					\
380452 } while (0)
381453 
382
-#define __put_user_check(x, ptr, err)					\
383
-({									\
454
+#define __put_user_error(x, ptr, err)					\
455
+do {									\
384456 	__typeof__(*(ptr)) __user *__p = (ptr);				\
385457 	might_fault();							\
386
-	if (access_ok(VERIFY_WRITE, __p, sizeof(*__p))) {		\
458
+	if (access_ok(__p, sizeof(*__p))) {				\
387459 		__p = uaccess_mask_ptr(__p);				\
388
-		__put_user_err((x), __p, (err));			\
460
+		__raw_put_user((x), __p, (err));			\
389461 	} else	{							\
390462 		(err) = -EFAULT;					\
391463 	}								\
392
-})
393
-
394
-#define __put_user_error(x, ptr, err)					\
395
-({									\
396
-	__put_user_check((x), (ptr), (err));				\
397
-	(void)0;							\
398
-})
464
+} while (0)
399465 
400466 #define __put_user(x, ptr)						\
401467 ({									\
402468 	int __pu_err = 0;						\
403
-	__put_user_check((x), (ptr), __pu_err);				\
469
+	__put_user_error((x), (ptr), __pu_err);				\
404470 	__pu_err;							\
405471 })
406472 
407473 #define put_user	__put_user
408474 
475
+/*
476
+ * We must not call into the scheduler between __uaccess_enable_tco_async() and
477
+ * __uaccess_disable_tco_async(). As `dst` and `src` may contain blocking
478
+ * functions, we must evaluate these outside of the critical section.
479
+ */
480
+#define __put_kernel_nofault(dst, src, type, err_label)			\
481
+do {									\
482
+	__typeof__(dst) __pkn_dst = (dst);				\
483
+	__typeof__(src) __pkn_src = (src);				\
484
+	int __pkn_err = 0;						\
485
+									\
486
+	__uaccess_enable_tco_async();					\
487
+	__raw_put_mem("str", *((type *)(__pkn_src)),			\
488
+		      (__force type *)(__pkn_dst), __pkn_err);		\
489
+	__uaccess_disable_tco_async();					\
490
+									\
491
+	if (unlikely(__pkn_err))					\
492
+		goto err_label;						\
493
+} while(0)
494
+
409495 extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n);
410496 #define raw_copy_from_user(to, from, n)					\
411497 ({									\
412
-	__arch_copy_from_user((to), __uaccess_mask_ptr(from), (n));	\
498
+	unsigned long __acfu_ret;					\
499
+	uaccess_enable_not_uao();					\
500
+	__acfu_ret = __arch_copy_from_user((to),			\
501
+				      __uaccess_mask_ptr(from), (n));	\
502
+	uaccess_disable_not_uao();					\
503
+	__acfu_ret;							\
413504 })
414505 
415506 extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n);
416507 #define raw_copy_to_user(to, from, n)					\
417508 ({									\
418
-	__arch_copy_to_user(__uaccess_mask_ptr(to), (from), (n));	\
509
+	unsigned long __actu_ret;					\
510
+	uaccess_enable_not_uao();					\
511
+	__actu_ret = __arch_copy_to_user(__uaccess_mask_ptr(to),	\
512
+				    (from), (n));			\
513
+	uaccess_disable_not_uao();					\
514
+	__actu_ret;							\
419515 })
420516 
421517 extern unsigned long __must_check __arch_copy_in_user(void __user *to, const void __user *from, unsigned long n);
422518 #define raw_copy_in_user(to, from, n)					\
423519 ({									\
424
-	__arch_copy_in_user(__uaccess_mask_ptr(to),			\
425
-			    __uaccess_mask_ptr(from), (n));		\
520
+	unsigned long __aciu_ret;					\
521
+	uaccess_enable_not_uao();					\
522
+	__aciu_ret = __arch_copy_in_user(__uaccess_mask_ptr(to),	\
523
+				    __uaccess_mask_ptr(from), (n));	\
524
+	uaccess_disable_not_uao();					\
525
+	__aciu_ret;							\
426526 })
427527 
428528 #define INLINE_COPY_TO_USER
....@@ -431,8 +531,11 @@
431531 extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned long n);
432532 static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n)
433533 {
434
-	if (access_ok(VERIFY_WRITE, to, n))
534
+	if (access_ok(to, n)) {
535
+		uaccess_enable_not_uao();
435536 		n = __arch_clear_user(__uaccess_mask_ptr(to), n);
537
+		uaccess_disable_not_uao();
538
+	}
436539 	return n;
437540 }
438541 #define clear_user	__clear_user