1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_UACCESS_H
3 #define _ASM_X86_UACCESS_H
4 /*
5 * User space memory access functions
6 */
7 #include <linux/compiler.h>
8 #include <linux/kasan-checks.h>
9 #include <linux/string.h>
10 #include <asm/asm.h>
11 #include <asm/page.h>
12 #include <asm/smap.h>
13 #include <asm/extable.h>
14
15 /*
16 * Test whether a block of memory is a valid user space address.
17 * Returns 0 if the range is valid, nonzero otherwise.
18 */
__chk_range_not_ok(unsigned long addr,unsigned long size,unsigned long limit)19 static inline bool __chk_range_not_ok(unsigned long addr, unsigned long size, unsigned long limit)
20 {
21 /*
22 * If we have used "sizeof()" for the size,
23 * we know it won't overflow the limit (but
24 * it might overflow the 'addr', so it's
25 * important to subtract the size from the
26 * limit, not add it to the address).
27 */
28 if (__builtin_constant_p(size))
29 return unlikely(addr > limit - size);
30
31 /* Arbitrary sizes? Be careful about overflow */
32 addr += size;
33 if (unlikely(addr < size))
34 return true;
35 return unlikely(addr > limit);
36 }
37
38 #define __range_not_ok(addr, size, limit) \
39 ({ \
40 __chk_user_ptr(addr); \
41 __chk_range_not_ok((unsigned long __force)(addr), size, limit); \
42 })
43
44 #ifdef CONFIG_DEBUG_ATOMIC_SLEEP
45 static inline bool pagefault_disabled(void);
46 # define WARN_ON_IN_IRQ() \
47 WARN_ON_ONCE(!in_task() && !pagefault_disabled())
48 #else
49 # define WARN_ON_IN_IRQ()
50 #endif
51
52 /**
53 * access_ok - Checks if a user space pointer is valid
54 * @addr: User space pointer to start of block to check
55 * @size: Size of block to check
56 *
57 * Context: User context only. This function may sleep if pagefaults are
58 * enabled.
59 *
60 * Checks if a pointer to a block of memory in user space is valid.
61 *
62 * Note that, depending on architecture, this function probably just
63 * checks that the pointer is in the user space range - after calling
64 * this function, memory access functions may still return -EFAULT.
65 *
66 * Return: true (nonzero) if the memory block may be valid, false (zero)
67 * if it is definitely invalid.
68 */
69 #define access_ok(addr, size) \
70 ({ \
71 WARN_ON_IN_IRQ(); \
72 likely(!__range_not_ok(addr, size, TASK_SIZE_MAX)); \
73 })
74
75 extern int __get_user_1(void);
76 extern int __get_user_2(void);
77 extern int __get_user_4(void);
78 extern int __get_user_8(void);
79 extern int __get_user_nocheck_1(void);
80 extern int __get_user_nocheck_2(void);
81 extern int __get_user_nocheck_4(void);
82 extern int __get_user_nocheck_8(void);
83 extern int __get_user_bad(void);
84
85 #define __uaccess_begin() stac()
86 #define __uaccess_end() clac()
87 #define __uaccess_begin_nospec() \
88 ({ \
89 stac(); \
90 barrier_nospec(); \
91 })
92
93 /*
94 * This is the smallest unsigned integer type that can fit a value
95 * (up to 'long long')
96 */
97 #define __inttype(x) __typeof__( \
98 __typefits(x,char, \
99 __typefits(x,short, \
100 __typefits(x,int, \
101 __typefits(x,long,0ULL)))))
102
103 #define __typefits(x,type,not) \
104 __builtin_choose_expr(sizeof(x)<=sizeof(type),(unsigned type)0,not)
105
106 /*
107 * This is used for both get_user() and __get_user() to expand to
108 * the proper special function call that has odd calling conventions
109 * due to returning both a value and an error, and that depends on
110 * the size of the pointer passed in.
111 *
112 * Careful: we have to cast the result to the type of the pointer
113 * for sign reasons.
114 *
115 * The use of _ASM_DX as the register specifier is a bit of a
116 * simplification, as gcc only cares about it as the starting point
117 * and not size: for a 64-bit value it will use %ecx:%edx on 32 bits
118 * (%ecx being the next register in gcc's x86 register sequence), and
119 * %rdx on 64 bits.
120 *
121 * Clang/LLVM cares about the size of the register, but still wants
122 * the base register for something that ends up being a pair.
123 */
124 #define do_get_user_call(fn,x,ptr) \
125 ({ \
126 int __ret_gu; \
127 register __inttype(*(ptr)) __val_gu asm("%"_ASM_DX); \
128 __chk_user_ptr(ptr); \
129 asm volatile("call __" #fn "_%P4" \
130 : "=a" (__ret_gu), "=r" (__val_gu), \
131 ASM_CALL_CONSTRAINT \
132 : "0" (ptr), "i" (sizeof(*(ptr)))); \
133 (x) = (__force __typeof__(*(ptr))) __val_gu; \
134 __builtin_expect(__ret_gu, 0); \
135 })
136
137 /**
138 * get_user - Get a simple variable from user space.
139 * @x: Variable to store result.
140 * @ptr: Source address, in user space.
141 *
142 * Context: User context only. This function may sleep if pagefaults are
143 * enabled.
144 *
145 * This macro copies a single simple variable from user space to kernel
146 * space. It supports simple types like char and int, but not larger
147 * data types like structures or arrays.
148 *
149 * @ptr must have pointer-to-simple-variable type, and the result of
150 * dereferencing @ptr must be assignable to @x without a cast.
151 *
152 * Return: zero on success, or -EFAULT on error.
153 * On error, the variable @x is set to zero.
154 */
155 #define get_user(x,ptr) ({ might_fault(); do_get_user_call(get_user,x,ptr); })
156
157 /**
158 * __get_user - Get a simple variable from user space, with less checking.
159 * @x: Variable to store result.
160 * @ptr: Source address, in user space.
161 *
162 * Context: User context only. This function may sleep if pagefaults are
163 * enabled.
164 *
165 * This macro copies a single simple variable from user space to kernel
166 * space. It supports simple types like char and int, but not larger
167 * data types like structures or arrays.
168 *
169 * @ptr must have pointer-to-simple-variable type, and the result of
170 * dereferencing @ptr must be assignable to @x without a cast.
171 *
172 * Caller must check the pointer with access_ok() before calling this
173 * function.
174 *
175 * Return: zero on success, or -EFAULT on error.
176 * On error, the variable @x is set to zero.
177 */
178 #define __get_user(x,ptr) do_get_user_call(get_user_nocheck,x,ptr)
179
180
181 #ifdef CONFIG_X86_32
182 #define __put_user_goto_u64(x, addr, label) \
183 asm_volatile_goto("\n" \
184 "1: movl %%eax,0(%1)\n" \
185 "2: movl %%edx,4(%1)\n" \
186 _ASM_EXTABLE_UA(1b, %l2) \
187 _ASM_EXTABLE_UA(2b, %l2) \
188 : : "A" (x), "r" (addr) \
189 : : label)
190
191 #else
192 #define __put_user_goto_u64(x, ptr, label) \
193 __put_user_goto(x, ptr, "q", "er", label)
194 #endif
195
196 extern void __put_user_bad(void);
197
198 /*
199 * Strange magic calling convention: pointer in %ecx,
200 * value in %eax(:%edx), return value in %ecx. clobbers %rbx
201 */
202 extern void __put_user_1(void);
203 extern void __put_user_2(void);
204 extern void __put_user_4(void);
205 extern void __put_user_8(void);
206 extern void __put_user_nocheck_1(void);
207 extern void __put_user_nocheck_2(void);
208 extern void __put_user_nocheck_4(void);
209 extern void __put_user_nocheck_8(void);
210
211 /*
212 * ptr must be evaluated and assigned to the temporary __ptr_pu before
213 * the assignment of x to __val_pu, to avoid any function calls
214 * involved in the ptr expression (possibly implicitly generated due
215 * to KASAN) from clobbering %ax.
216 */
217 #define do_put_user_call(fn,x,ptr) \
218 ({ \
219 int __ret_pu; \
220 void __user *__ptr_pu; \
221 register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX); \
222 __chk_user_ptr(ptr); \
223 __ptr_pu = (ptr); \
224 __val_pu = (x); \
225 asm volatile("call __" #fn "_%P[size]" \
226 : "=c" (__ret_pu), \
227 ASM_CALL_CONSTRAINT \
228 : "0" (__ptr_pu), \
229 "r" (__val_pu), \
230 [size] "i" (sizeof(*(ptr))) \
231 :"ebx"); \
232 __builtin_expect(__ret_pu, 0); \
233 })
234
235 /**
236 * put_user - Write a simple value into user space.
237 * @x: Value to copy to user space.
238 * @ptr: Destination address, in user space.
239 *
240 * Context: User context only. This function may sleep if pagefaults are
241 * enabled.
242 *
243 * This macro copies a single simple value from kernel space to user
244 * space. It supports simple types like char and int, but not larger
245 * data types like structures or arrays.
246 *
247 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
248 * to the result of dereferencing @ptr.
249 *
250 * Return: zero on success, or -EFAULT on error.
251 */
252 #define put_user(x, ptr) ({ might_fault(); do_put_user_call(put_user,x,ptr); })
253
254 /**
255 * __put_user - Write a simple value into user space, with less checking.
256 * @x: Value to copy to user space.
257 * @ptr: Destination address, in user space.
258 *
259 * Context: User context only. This function may sleep if pagefaults are
260 * enabled.
261 *
262 * This macro copies a single simple value from kernel space to user
263 * space. It supports simple types like char and int, but not larger
264 * data types like structures or arrays.
265 *
266 * @ptr must have pointer-to-simple-variable type, and @x must be assignable
267 * to the result of dereferencing @ptr.
268 *
269 * Caller must check the pointer with access_ok() before calling this
270 * function.
271 *
272 * Return: zero on success, or -EFAULT on error.
273 */
274 #define __put_user(x, ptr) do_put_user_call(put_user_nocheck,x,ptr)
275
276 #define __put_user_size(x, ptr, size, label) \
277 do { \
278 __chk_user_ptr(ptr); \
279 switch (size) { \
280 case 1: \
281 __put_user_goto(x, ptr, "b", "iq", label); \
282 break; \
283 case 2: \
284 __put_user_goto(x, ptr, "w", "ir", label); \
285 break; \
286 case 4: \
287 __put_user_goto(x, ptr, "l", "ir", label); \
288 break; \
289 case 8: \
290 __put_user_goto_u64(x, ptr, label); \
291 break; \
292 default: \
293 __put_user_bad(); \
294 } \
295 } while (0)
296
297 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
298
299 #ifdef CONFIG_X86_32
300 #define __get_user_asm_u64(x, ptr, label) do { \
301 unsigned int __gu_low, __gu_high; \
302 const unsigned int __user *__gu_ptr; \
303 __gu_ptr = (const void __user *)(ptr); \
304 __get_user_asm(__gu_low, __gu_ptr, "l", "=r", label); \
305 __get_user_asm(__gu_high, __gu_ptr+1, "l", "=r", label); \
306 (x) = ((unsigned long long)__gu_high << 32) | __gu_low; \
307 } while (0)
308 #else
309 #define __get_user_asm_u64(x, ptr, label) \
310 __get_user_asm(x, ptr, "q", "=r", label)
311 #endif
312
313 #define __get_user_size(x, ptr, size, label) \
314 do { \
315 __chk_user_ptr(ptr); \
316 switch (size) { \
317 case 1: { \
318 unsigned char x_u8__; \
319 __get_user_asm(x_u8__, ptr, "b", "=q", label); \
320 (x) = x_u8__; \
321 break; \
322 } \
323 case 2: \
324 __get_user_asm(x, ptr, "w", "=r", label); \
325 break; \
326 case 4: \
327 __get_user_asm(x, ptr, "l", "=r", label); \
328 break; \
329 case 8: \
330 __get_user_asm_u64(x, ptr, label); \
331 break; \
332 default: \
333 (x) = __get_user_bad(); \
334 } \
335 } while (0)
336
337 #define __get_user_asm(x, addr, itype, ltype, label) \
338 asm_volatile_goto("\n" \
339 "1: mov"itype" %[umem],%[output]\n" \
340 _ASM_EXTABLE_UA(1b, %l2) \
341 : [output] ltype(x) \
342 : [umem] "m" (__m(addr)) \
343 : : label)
344
345 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
346
347 #ifdef CONFIG_X86_32
348 #define __get_user_asm_u64(x, ptr, retval) \
349 ({ \
350 __typeof__(ptr) __ptr = (ptr); \
351 asm volatile("\n" \
352 "1: movl %[lowbits],%%eax\n" \
353 "2: movl %[highbits],%%edx\n" \
354 "3:\n" \
355 ".section .fixup,\"ax\"\n" \
356 "4: mov %[efault],%[errout]\n" \
357 " xorl %%eax,%%eax\n" \
358 " xorl %%edx,%%edx\n" \
359 " jmp 3b\n" \
360 ".previous\n" \
361 _ASM_EXTABLE_UA(1b, 4b) \
362 _ASM_EXTABLE_UA(2b, 4b) \
363 : [errout] "=r" (retval), \
364 [output] "=&A"(x) \
365 : [lowbits] "m" (__m(__ptr)), \
366 [highbits] "m" __m(((u32 __user *)(__ptr)) + 1), \
367 [efault] "i" (-EFAULT), "0" (retval)); \
368 })
369
370 #else
371 #define __get_user_asm_u64(x, ptr, retval) \
372 __get_user_asm(x, ptr, retval, "q", "=r")
373 #endif
374
375 #define __get_user_size(x, ptr, size, retval) \
376 do { \
377 unsigned char x_u8__; \
378 \
379 retval = 0; \
380 __chk_user_ptr(ptr); \
381 switch (size) { \
382 case 1: \
383 __get_user_asm(x_u8__, ptr, retval, "b", "=q"); \
384 (x) = x_u8__; \
385 break; \
386 case 2: \
387 __get_user_asm(x, ptr, retval, "w", "=r"); \
388 break; \
389 case 4: \
390 __get_user_asm(x, ptr, retval, "l", "=r"); \
391 break; \
392 case 8: \
393 __get_user_asm_u64(x, ptr, retval); \
394 break; \
395 default: \
396 (x) = __get_user_bad(); \
397 } \
398 } while (0)
399
400 #define __get_user_asm(x, addr, err, itype, ltype) \
401 asm volatile("\n" \
402 "1: mov"itype" %[umem],%[output]\n" \
403 "2:\n" \
404 ".section .fixup,\"ax\"\n" \
405 "3: mov %[efault],%[errout]\n" \
406 " xorl %k[output],%k[output]\n" \
407 " jmp 2b\n" \
408 ".previous\n" \
409 _ASM_EXTABLE_UA(1b, 3b) \
410 : [errout] "=r" (err), \
411 [output] ltype(x) \
412 : [umem] "m" (__m(addr)), \
413 [efault] "i" (-EFAULT), "0" (err))
414
415 #endif // CONFIG_CC_ASM_GOTO_OUTPUT
416
417 /* FIXME: this hack is definitely wrong -AK */
418 struct __large_struct { unsigned long buf[100]; };
419 #define __m(x) (*(struct __large_struct __user *)(x))
420
421 /*
422 * Tell gcc we read from memory instead of writing: this is because
423 * we do not write to any memory gcc knows about, so there are no
424 * aliasing issues.
425 */
426 #define __put_user_goto(x, addr, itype, ltype, label) \
427 asm_volatile_goto("\n" \
428 "1: mov"itype" %0,%1\n" \
429 _ASM_EXTABLE_UA(1b, %l2) \
430 : : ltype(x), "m" (__m(addr)) \
431 : : label)
432
433 extern unsigned long
434 copy_from_user_nmi(void *to, const void __user *from, unsigned long n);
435 extern __must_check long
436 strncpy_from_user(char *dst, const char __user *src, long count);
437
438 extern __must_check long strnlen_user(const char __user *str, long n);
439
440 unsigned long __must_check clear_user(void __user *mem, unsigned long len);
441 unsigned long __must_check __clear_user(void __user *mem, unsigned long len);
442
443 #ifdef CONFIG_ARCH_HAS_COPY_MC
444 unsigned long __must_check
445 copy_mc_to_kernel(void *to, const void *from, unsigned len);
446 #define copy_mc_to_kernel copy_mc_to_kernel
447
448 unsigned long __must_check
449 copy_mc_to_user(void *to, const void *from, unsigned len);
450 #endif
451
452 /*
453 * movsl can be slow when source and dest are not both 8-byte aligned
454 */
455 #ifdef CONFIG_X86_INTEL_USERCOPY
456 extern struct movsl_mask {
457 int mask;
458 } ____cacheline_aligned_in_smp movsl_mask;
459 #endif
460
461 #define ARCH_HAS_NOCACHE_UACCESS 1
462
463 #ifdef CONFIG_X86_32
464 # include <asm/uaccess_32.h>
465 #else
466 # include <asm/uaccess_64.h>
467 #endif
468
469 /*
470 * The "unsafe" user accesses aren't really "unsafe", but the naming
471 * is a big fat warning: you have to not only do the access_ok()
472 * checking before using them, but you have to surround them with the
473 * user_access_begin/end() pair.
474 */
user_access_begin(const void __user * ptr,size_t len)475 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len)
476 {
477 if (unlikely(!access_ok(ptr,len)))
478 return 0;
479 __uaccess_begin_nospec();
480 return 1;
481 }
482 #define user_access_begin(a,b) user_access_begin(a,b)
483 #define user_access_end() __uaccess_end()
484
485 #define user_access_save() smap_save()
486 #define user_access_restore(x) smap_restore(x)
487
488 #define unsafe_put_user(x, ptr, label) \
489 __put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
490
491 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
492 #define unsafe_get_user(x, ptr, err_label) \
493 do { \
494 __inttype(*(ptr)) __gu_val; \
495 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label); \
496 (x) = (__force __typeof__(*(ptr)))__gu_val; \
497 } while (0)
498 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
499 #define unsafe_get_user(x, ptr, err_label) \
500 do { \
501 int __gu_err; \
502 __inttype(*(ptr)) __gu_val; \
503 __get_user_size(__gu_val, (ptr), sizeof(*(ptr)), __gu_err); \
504 (x) = (__force __typeof__(*(ptr)))__gu_val; \
505 if (unlikely(__gu_err)) goto err_label; \
506 } while (0)
507 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
508
509 /*
510 * We want the unsafe accessors to always be inlined and use
511 * the error labels - thus the macro games.
512 */
513 #define unsafe_copy_loop(dst, src, len, type, label) \
514 while (len >= sizeof(type)) { \
515 unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \
516 dst += sizeof(type); \
517 src += sizeof(type); \
518 len -= sizeof(type); \
519 }
520
521 #define unsafe_copy_to_user(_dst,_src,_len,label) \
522 do { \
523 char __user *__ucu_dst = (_dst); \
524 const char *__ucu_src = (_src); \
525 size_t __ucu_len = (_len); \
526 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \
527 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \
528 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \
529 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \
530 } while (0)
531
532 #define HAVE_GET_KERNEL_NOFAULT
533
534 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
535 #define __get_kernel_nofault(dst, src, type, err_label) \
536 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \
537 sizeof(type), err_label)
538 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
539 #define __get_kernel_nofault(dst, src, type, err_label) \
540 do { \
541 int __kr_err; \
542 \
543 __get_user_size(*((type *)(dst)), (__force type __user *)(src), \
544 sizeof(type), __kr_err); \
545 if (unlikely(__kr_err)) \
546 goto err_label; \
547 } while (0)
548 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
549
550 #define __put_kernel_nofault(dst, src, type, err_label) \
551 __put_user_size(*((type *)(src)), (__force type __user *)(dst), \
552 sizeof(type), err_label)
553
554 #endif /* _ASM_X86_UACCESS_H */
555
556