Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * arch/arm/include/asm/uaccess.h
4 */
5#ifndef _ASMARM_UACCESS_H
6#define _ASMARM_UACCESS_H
7
8/*
9 * User space memory access functions
10 */
11#include <linux/kernel.h>
12#include <linux/string.h>
13#include <asm/page.h>
14#include <asm/domain.h>
15#include <linux/unaligned.h>
16#include <asm/unified.h>
17#include <asm/pgtable.h>
18#include <asm/proc-fns.h>
19#include <asm/compiler.h>
20
21#include <asm/extable.h>
22
23/*
24 * These two functions allow hooking accesses to userspace to increase
25 * system integrity by ensuring that the kernel can not inadvertantly
26 * perform such accesses (eg, via list poison values) which could then
27 * be exploited for priviledge escalation.
28 */
29#if defined(CONFIG_CPU_SW_DOMAIN_PAN)
30
31static __always_inline unsigned int uaccess_save_and_enable(void)
32{
33 unsigned int old_domain = get_domain();
34
35 /* Set the current domain access to permit user accesses */
36 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) |
37 domain_val(DOMAIN_USER, DOMAIN_CLIENT));
38
39 return old_domain;
40}
41
42static __always_inline void uaccess_restore(unsigned int flags)
43{
44 /* Restore the user access mask */
45 set_domain(flags);
46}
47
48#elif defined(CONFIG_CPU_TTBR0_PAN)
49
50static __always_inline unsigned int uaccess_save_and_enable(void)
51{
52 unsigned int old_ttbcr = cpu_get_ttbcr();
53
54 /*
55 * Enable TTBR0 page table walks (T0SZ = 0, EDP0 = 0) and ASID from
56 * TTBR0 (A1 = 0).
57 */
58 cpu_set_ttbcr(old_ttbcr & ~(TTBCR_A1 | TTBCR_EPD0 | TTBCR_T0SZ_MASK));
59 isb();
60
61 return old_ttbcr;
62}
63
64static inline void uaccess_restore(unsigned int flags)
65{
66 cpu_set_ttbcr(flags);
67 isb();
68}
69
70#else
71
72static inline unsigned int uaccess_save_and_enable(void)
73{
74 return 0;
75}
76
77static inline void uaccess_restore(unsigned int flags)
78{
79}
80
81#endif
82
83/*
84 * These two are intentionally not defined anywhere - if the kernel
85 * code generates any references to them, that's a bug.
86 */
87extern int __get_user_bad(void);
88extern int __put_user_bad(void);
89
90#ifdef CONFIG_MMU
91
92/*
93 * This is a type: either unsigned long, if the argument fits into
94 * that type, or otherwise unsigned long long.
95 */
96#define __inttype(x) \
97 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
98
99/*
100 * Sanitise a uaccess pointer such that it becomes NULL if addr+size
101 * is above the current addr_limit.
102 */
103#define uaccess_mask_range_ptr(ptr, size) \
104 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size))
105static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr,
106 size_t size)
107{
108 void __user *safe_ptr = (void __user *)ptr;
109 unsigned long tmp;
110
111 asm volatile(
112 " .syntax unified\n"
113 " sub %1, %3, #1\n"
114 " subs %1, %1, %0\n"
115 " addhs %1, %1, #1\n"
116 " subshs %1, %1, %2\n"
117 " movlo %0, #0\n"
118 : "+r" (safe_ptr), "=&r" (tmp)
119 : "r" (size), "r" (TASK_SIZE)
120 : "cc");
121
122 csdb();
123 return safe_ptr;
124}
125
126/*
127 * Single-value transfer routines. They automatically use the right
128 * size if we just have the right pointer type. Note that the functions
129 * which read from user space (*get_*) need to take care not to leak
130 * kernel data even if the calling code is buggy and fails to check
131 * the return value. This means zeroing out the destination variable
132 * or buffer on error. Normally this is done out of line by the
133 * fixup code, but there are a few places where it intrudes on the
134 * main code path. When we only write to user space, there is no
135 * problem.
136 */
137extern int __get_user_1(void *);
138extern int __get_user_2(void *);
139extern int __get_user_4(void *);
140extern int __get_user_32t_8(void *);
141extern int __get_user_8(void *);
142extern int __get_user_64t_1(void *);
143extern int __get_user_64t_2(void *);
144extern int __get_user_64t_4(void *);
145
146#define __get_user_x(__r2, __p, __e, __l, __s) \
147 __asm__ __volatile__ ( \
148 __asmeq("%0", "r0") __asmeq("%1", "r2") \
149 __asmeq("%3", "r1") \
150 "bl __get_user_" #__s \
151 : "=&r" (__e), "=r" (__r2) \
152 : "0" (__p), "r" (__l) \
153 : "ip", "lr", "cc")
154
155/* narrowing a double-word get into a single 32bit word register: */
156#ifdef __ARMEB__
157#define __get_user_x_32t(__r2, __p, __e, __l, __s) \
158 __get_user_x(__r2, __p, __e, __l, 32t_8)
159#else
160#define __get_user_x_32t __get_user_x
161#endif
162
163/*
164 * storing result into proper least significant word of 64bit target var,
165 * different only for big endian case where 64 bit __r2 lsw is r3:
166 */
167#ifdef __ARMEB__
168#define __get_user_x_64t(__r2, __p, __e, __l, __s) \
169 __asm__ __volatile__ ( \
170 __asmeq("%0", "r0") __asmeq("%1", "r2") \
171 __asmeq("%3", "r1") \
172 "bl __get_user_64t_" #__s \
173 : "=&r" (__e), "=r" (__r2) \
174 : "0" (__p), "r" (__l) \
175 : "ip", "lr", "cc")
176#else
177#define __get_user_x_64t __get_user_x
178#endif
179
180
181#define __get_user_check(x, p) \
182 ({ \
183 unsigned long __limit = TASK_SIZE - 1; \
184 register typeof(*(p)) __user *__p asm("r0") = (p); \
185 register __inttype(x) __r2 asm("r2"); \
186 register unsigned long __l asm("r1") = __limit; \
187 register int __e asm("r0"); \
188 unsigned int __ua_flags = uaccess_save_and_enable(); \
189 int __tmp_e; \
190 switch (sizeof(*(__p))) { \
191 case 1: \
192 if (sizeof((x)) >= 8) \
193 __get_user_x_64t(__r2, __p, __e, __l, 1); \
194 else \
195 __get_user_x(__r2, __p, __e, __l, 1); \
196 break; \
197 case 2: \
198 if (sizeof((x)) >= 8) \
199 __get_user_x_64t(__r2, __p, __e, __l, 2); \
200 else \
201 __get_user_x(__r2, __p, __e, __l, 2); \
202 break; \
203 case 4: \
204 if (sizeof((x)) >= 8) \
205 __get_user_x_64t(__r2, __p, __e, __l, 4); \
206 else \
207 __get_user_x(__r2, __p, __e, __l, 4); \
208 break; \
209 case 8: \
210 if (sizeof((x)) < 8) \
211 __get_user_x_32t(__r2, __p, __e, __l, 4); \
212 else \
213 __get_user_x(__r2, __p, __e, __l, 8); \
214 break; \
215 default: __e = __get_user_bad(); break; \
216 } \
217 __tmp_e = __e; \
218 uaccess_restore(__ua_flags); \
219 x = (typeof(*(p))) __r2; \
220 __tmp_e; \
221 })
222
223#define get_user(x, p) \
224 ({ \
225 might_fault(); \
226 __get_user_check(x, p); \
227 })
228
229extern int __put_user_1(void *, unsigned int);
230extern int __put_user_2(void *, unsigned int);
231extern int __put_user_4(void *, unsigned int);
232extern int __put_user_8(void *, unsigned long long);
233
234#define __put_user_check(__pu_val, __ptr, __err, __s) \
235 ({ \
236 unsigned long __limit = TASK_SIZE - 1; \
237 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \
238 register const void __user *__p asm("r0") = __ptr; \
239 register unsigned long __l asm("r1") = __limit; \
240 register int __e asm("r0"); \
241 __asm__ __volatile__ ( \
242 __asmeq("%0", "r0") __asmeq("%2", "r2") \
243 __asmeq("%3", "r1") \
244 "bl __put_user_" #__s \
245 : "=&r" (__e) \
246 : "0" (__p), "r" (__r2), "r" (__l) \
247 : "ip", "lr", "cc"); \
248 __err = __e; \
249 })
250
251#else /* CONFIG_MMU */
252
253#define get_user(x, p) __get_user(x, p)
254#define __put_user_check __put_user_nocheck
255
256#endif /* CONFIG_MMU */
257
258#include <asm-generic/access_ok.h>
259
260#ifdef CONFIG_CPU_SPECTRE
261/*
262 * When mitigating Spectre variant 1, it is not worth fixing the non-
263 * verifying accessors, because we need to add verification of the
264 * address space there. Force these to use the standard get_user()
265 * version instead.
266 */
267#define __get_user(x, ptr) get_user(x, ptr)
268#else
269
270/*
271 * The "__xxx" versions of the user access functions do not verify the
272 * address space - it must have been done previously with a separate
273 * "access_ok()" call.
274 *
275 * The "xxx_error" versions set the third argument to EFAULT if an
276 * error occurs, and leave it unchanged on success. Note that these
277 * versions are void (ie, don't return a value as such).
278 */
279#define __get_user(x, ptr) \
280({ \
281 long __gu_err = 0; \
282 __get_user_err((x), (ptr), __gu_err, TUSER()); \
283 __gu_err; \
284})
285
286/*
287 * This is a type: either unsigned long, if the argument fits into
288 * that type, or otherwise unsigned long long.
289 */
290#define __long_type(x) \
291 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL))
292
293#define __get_user_err(x, ptr, err, __t) \
294do { \
295 unsigned long __gu_addr = (unsigned long)(ptr); \
296 __long_type(x) __gu_val; \
297 unsigned int __ua_flags; \
298 __chk_user_ptr(ptr); \
299 might_fault(); \
300 __ua_flags = uaccess_save_and_enable(); \
301 switch (sizeof(*(ptr))) { \
302 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \
303 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \
304 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \
305 case 8: __get_user_asm_dword(__gu_val, __gu_addr, err, __t); break; \
306 default: (__gu_val) = __get_user_bad(); \
307 } \
308 uaccess_restore(__ua_flags); \
309 (x) = (__typeof__(*(ptr)))__gu_val; \
310} while (0)
311#endif
312
313#define __get_user_asm(x, addr, err, instr) \
314 __asm__ __volatile__( \
315 "1: " instr " %1, [%2], #0\n" \
316 "2:\n" \
317 " .pushsection .text.fixup,\"ax\"\n" \
318 " .align 2\n" \
319 "3: mov %0, %3\n" \
320 " mov %1, #0\n" \
321 " b 2b\n" \
322 " .popsection\n" \
323 " .pushsection __ex_table,\"a\"\n" \
324 " .align 3\n" \
325 " .long 1b, 3b\n" \
326 " .popsection" \
327 : "+r" (err), "=&r" (x) \
328 : "r" (addr), "i" (-EFAULT) \
329 : "cc")
330
331#define __get_user_asm_byte(x, addr, err, __t) \
332 __get_user_asm(x, addr, err, "ldrb" __t)
333
334#if __LINUX_ARM_ARCH__ >= 6
335
336#define __get_user_asm_half(x, addr, err, __t) \
337 __get_user_asm(x, addr, err, "ldrh" __t)
338
339#else
340
341#ifndef __ARMEB__
342#define __get_user_asm_half(x, __gu_addr, err, __t) \
343({ \
344 unsigned long __b1, __b2; \
345 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
346 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
347 (x) = __b1 | (__b2 << 8); \
348})
349#else
350#define __get_user_asm_half(x, __gu_addr, err, __t) \
351({ \
352 unsigned long __b1, __b2; \
353 __get_user_asm_byte(__b1, __gu_addr, err, __t); \
354 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \
355 (x) = (__b1 << 8) | __b2; \
356})
357#endif
358
359#endif /* __LINUX_ARM_ARCH__ >= 6 */
360
361#define __get_user_asm_word(x, addr, err, __t) \
362 __get_user_asm(x, addr, err, "ldr" __t)
363
364#ifdef __ARMEB__
365#define __WORD0_OFFS 4
366#define __WORD1_OFFS 0
367#else
368#define __WORD0_OFFS 0
369#define __WORD1_OFFS 4
370#endif
371
372#define __get_user_asm_dword(x, addr, err, __t) \
373 ({ \
374 unsigned long __w0, __w1; \
375 __get_user_asm(__w0, addr + __WORD0_OFFS, err, "ldr" __t); \
376 __get_user_asm(__w1, addr + __WORD1_OFFS, err, "ldr" __t); \
377 (x) = ((u64)__w1 << 32) | (u64) __w0; \
378})
379
380#define __put_user_switch(x, ptr, __err, __fn) \
381 do { \
382 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \
383 __typeof__(*(ptr)) __pu_val = (x); \
384 unsigned int __ua_flags; \
385 might_fault(); \
386 __ua_flags = uaccess_save_and_enable(); \
387 switch (sizeof(*(ptr))) { \
388 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \
389 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \
390 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \
391 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \
392 default: __err = __put_user_bad(); break; \
393 } \
394 uaccess_restore(__ua_flags); \
395 } while (0)
396
397#define put_user(x, ptr) \
398({ \
399 int __pu_err = 0; \
400 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \
401 __pu_err; \
402})
403
404#ifdef CONFIG_CPU_SPECTRE
405/*
406 * When mitigating Spectre variant 1.1, all accessors need to include
407 * verification of the address space.
408 */
409#define __put_user(x, ptr) put_user(x, ptr)
410
411#else
412#define __put_user(x, ptr) \
413({ \
414 long __pu_err = 0; \
415 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \
416 __pu_err; \
417})
418
419#define __put_user_nocheck(x, __pu_ptr, __err, __size) \
420 do { \
421 unsigned long __pu_addr = (unsigned long)__pu_ptr; \
422 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\
423 } while (0)
424
425#define __put_user_nocheck_1 __put_user_asm_byte
426#define __put_user_nocheck_2 __put_user_asm_half
427#define __put_user_nocheck_4 __put_user_asm_word
428#define __put_user_nocheck_8 __put_user_asm_dword
429
430#endif /* !CONFIG_CPU_SPECTRE */
431
432#define __put_user_asm(x, __pu_addr, err, instr) \
433 __asm__ __volatile__( \
434 "1: " instr " %1, [%2], #0\n" \
435 "2:\n" \
436 " .pushsection .text.fixup,\"ax\"\n" \
437 " .align 2\n" \
438 "3: mov %0, %3\n" \
439 " b 2b\n" \
440 " .popsection\n" \
441 " .pushsection __ex_table,\"a\"\n" \
442 " .align 3\n" \
443 " .long 1b, 3b\n" \
444 " .popsection" \
445 : "+r" (err) \
446 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \
447 : "cc")
448
449#define __put_user_asm_byte(x, __pu_addr, err, __t) \
450 __put_user_asm(x, __pu_addr, err, "strb" __t)
451
452#if __LINUX_ARM_ARCH__ >= 6
453
454#define __put_user_asm_half(x, __pu_addr, err, __t) \
455 __put_user_asm(x, __pu_addr, err, "strh" __t)
456
457#else
458
459#ifndef __ARMEB__
460#define __put_user_asm_half(x, __pu_addr, err, __t) \
461({ \
462 unsigned long __temp = (__force unsigned long)(x); \
463 __put_user_asm_byte(__temp, __pu_addr, err, __t); \
464 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\
465})
466#else
467#define __put_user_asm_half(x, __pu_addr, err, __t) \
468({ \
469 unsigned long __temp = (__force unsigned long)(x); \
470 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \
471 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \
472})
473#endif
474
475#endif /* __LINUX_ARM_ARCH__ >= 6 */
476
477#define __put_user_asm_word(x, __pu_addr, err, __t) \
478 __put_user_asm(x, __pu_addr, err, "str" __t)
479
480#ifndef __ARMEB__
481#define __reg_oper0 "%R2"
482#define __reg_oper1 "%Q2"
483#else
484#define __reg_oper0 "%Q2"
485#define __reg_oper1 "%R2"
486#endif
487
488#define __put_user_asm_dword(x, __pu_addr, err, __t) \
489 __asm__ __volatile__( \
490 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \
491 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \
492 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \
493 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \
494 "3:\n" \
495 " .pushsection .text.fixup,\"ax\"\n" \
496 " .align 2\n" \
497 "4: mov %0, %3\n" \
498 " b 3b\n" \
499 " .popsection\n" \
500 " .pushsection __ex_table,\"a\"\n" \
501 " .align 3\n" \
502 " .long 1b, 4b\n" \
503 " .long 2b, 4b\n" \
504 " .popsection" \
505 : "+r" (err), "+r" (__pu_addr) \
506 : "r" (x), "i" (-EFAULT) \
507 : "cc")
508
509#define __get_kernel_nofault(dst, src, type, err_label) \
510do { \
511 const type *__pk_ptr = (src); \
512 unsigned long __src = (unsigned long)(__pk_ptr); \
513 type __val; \
514 int __err = 0; \
515 switch (sizeof(type)) { \
516 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \
517 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \
518 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \
519 case 8: { \
520 u32 *__v32 = (u32*)&__val; \
521 __get_user_asm_word(__v32[0], __src, __err, ""); \
522 if (__err) \
523 break; \
524 __get_user_asm_word(__v32[1], __src+4, __err, ""); \
525 break; \
526 } \
527 default: __err = __get_user_bad(); break; \
528 } \
529 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) \
530 put_unaligned(__val, (type *)(dst)); \
531 else \
532 *(type *)(dst) = __val; /* aligned by caller */ \
533 if (__err) \
534 goto err_label; \
535} while (0)
536
537#define __put_kernel_nofault(dst, src, type, err_label) \
538do { \
539 const type *__pk_ptr = (dst); \
540 unsigned long __dst = (unsigned long)__pk_ptr; \
541 int __err = 0; \
542 type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \
543 ? get_unaligned((type *)(src)) \
544 : *(type *)(src); /* aligned by caller */ \
545 switch (sizeof(type)) { \
546 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \
547 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \
548 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \
549 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \
550 default: __err = __put_user_bad(); break; \
551 } \
552 if (__err) \
553 goto err_label; \
554} while (0)
555
556#ifdef CONFIG_MMU
557extern unsigned long __must_check
558arm_copy_from_user(void *to, const void __user *from, unsigned long n);
559
560static inline unsigned long __must_check
561raw_copy_from_user(void *to, const void __user *from, unsigned long n)
562{
563 unsigned int __ua_flags;
564
565 __ua_flags = uaccess_save_and_enable();
566 n = arm_copy_from_user(to, from, n);
567 uaccess_restore(__ua_flags);
568 return n;
569}
570
571extern unsigned long __must_check
572arm_copy_to_user(void __user *to, const void *from, unsigned long n);
573extern unsigned long __must_check
574__copy_to_user_std(void __user *to, const void *from, unsigned long n);
575
576static inline unsigned long __must_check
577raw_copy_to_user(void __user *to, const void *from, unsigned long n)
578{
579#ifndef CONFIG_UACCESS_WITH_MEMCPY
580 unsigned int __ua_flags;
581 __ua_flags = uaccess_save_and_enable();
582 n = arm_copy_to_user(to, from, n);
583 uaccess_restore(__ua_flags);
584 return n;
585#else
586 return arm_copy_to_user(to, from, n);
587#endif
588}
589
590extern unsigned long __must_check
591arm_clear_user(void __user *addr, unsigned long n);
592extern unsigned long __must_check
593__clear_user_std(void __user *addr, unsigned long n);
594
595static inline unsigned long __must_check
596__clear_user(void __user *addr, unsigned long n)
597{
598 unsigned int __ua_flags = uaccess_save_and_enable();
599 n = arm_clear_user(addr, n);
600 uaccess_restore(__ua_flags);
601 return n;
602}
603
604#else
605static inline unsigned long
606raw_copy_from_user(void *to, const void __user *from, unsigned long n)
607{
608 memcpy(to, (const void __force *)from, n);
609 return 0;
610}
611static inline unsigned long
612raw_copy_to_user(void __user *to, const void *from, unsigned long n)
613{
614 memcpy((void __force *)to, from, n);
615 return 0;
616}
617#define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0)
618#endif
619#define INLINE_COPY_TO_USER
620#define INLINE_COPY_FROM_USER
621
622static inline unsigned long __must_check clear_user(void __user *to, unsigned long n)
623{
624 if (access_ok(to, n))
625 n = __clear_user(to, n);
626 return n;
627}
628
629/* These are from lib/ code, and use __get_user() and friends */
630extern long strncpy_from_user(char *dest, const char __user *src, long count);
631
632extern __must_check long strnlen_user(const char __user *str, long n);
633
634#endif /* _ASMARM_UACCESS_H */