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/string.h> 12 #include <asm/memory.h> 13 #include <asm/domain.h> 14 #include <asm/unified.h> 15 #include <asm/compiler.h> 16 17 #include <asm/extable.h> 18 19 /* 20 * These two functions allow hooking accesses to userspace to increase 21 * system integrity by ensuring that the kernel can not inadvertantly 22 * perform such accesses (eg, via list poison values) which could then 23 * be exploited for priviledge escalation. 24 */ 25 static __always_inline unsigned int uaccess_save_and_enable(void) 26 { 27 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 28 unsigned int old_domain = get_domain(); 29 30 /* Set the current domain access to permit user accesses */ 31 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) | 32 domain_val(DOMAIN_USER, DOMAIN_CLIENT)); 33 34 return old_domain; 35 #else 36 return 0; 37 #endif 38 } 39 40 static __always_inline void uaccess_restore(unsigned int flags) 41 { 42 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 43 /* Restore the user access mask */ 44 set_domain(flags); 45 #endif 46 } 47 48 /* 49 * These two are intentionally not defined anywhere - if the kernel 50 * code generates any references to them, that's a bug. 51 */ 52 extern int __get_user_bad(void); 53 extern int __put_user_bad(void); 54 55 /* 56 * Note that this is actually 0x1,0000,0000 57 */ 58 #define KERNEL_DS 0x00000000 59 60 #ifdef CONFIG_MMU 61 62 #define USER_DS TASK_SIZE 63 #define get_fs() (current_thread_info()->addr_limit) 64 65 static inline void set_fs(mm_segment_t fs) 66 { 67 current_thread_info()->addr_limit = fs; 68 69 /* 70 * Prevent a mispredicted conditional call to set_fs from forwarding 71 * the wrong address limit to access_ok under speculation. 72 */ 73 dsb(nsh); 74 isb(); 75 76 modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); 77 } 78 79 #define uaccess_kernel() (get_fs() == KERNEL_DS) 80 81 /* 82 * We use 33-bit arithmetic here. Success returns zero, failure returns 83 * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS, 84 * so this will always return success in that case. 85 */ 86 #define __range_ok(addr, size) ({ \ 87 unsigned long flag, roksum; \ 88 __chk_user_ptr(addr); \ 89 __asm__(".syntax unified\n" \ 90 "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \ 91 : "=&r" (flag), "=&r" (roksum) \ 92 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ 93 : "cc"); \ 94 flag; }) 95 96 /* 97 * This is a type: either unsigned long, if the argument fits into 98 * that type, or otherwise unsigned long long. 99 */ 100 #define __inttype(x) \ 101 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 102 103 /* 104 * Sanitise a uaccess pointer such that it becomes NULL if addr+size 105 * is above the current addr_limit. 106 */ 107 #define uaccess_mask_range_ptr(ptr, size) \ 108 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size)) 109 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, 110 size_t size) 111 { 112 void __user *safe_ptr = (void __user *)ptr; 113 unsigned long tmp; 114 115 asm volatile( 116 " .syntax unified\n" 117 " sub %1, %3, #1\n" 118 " subs %1, %1, %0\n" 119 " addhs %1, %1, #1\n" 120 " subshs %1, %1, %2\n" 121 " movlo %0, #0\n" 122 : "+r" (safe_ptr), "=&r" (tmp) 123 : "r" (size), "r" (current_thread_info()->addr_limit) 124 : "cc"); 125 126 csdb(); 127 return safe_ptr; 128 } 129 130 /* 131 * Single-value transfer routines. They automatically use the right 132 * size if we just have the right pointer type. Note that the functions 133 * which read from user space (*get_*) need to take care not to leak 134 * kernel data even if the calling code is buggy and fails to check 135 * the return value. This means zeroing out the destination variable 136 * or buffer on error. Normally this is done out of line by the 137 * fixup code, but there are a few places where it intrudes on the 138 * main code path. When we only write to user space, there is no 139 * problem. 140 */ 141 extern int __get_user_1(void *); 142 extern int __get_user_2(void *); 143 extern int __get_user_4(void *); 144 extern int __get_user_32t_8(void *); 145 extern int __get_user_8(void *); 146 extern int __get_user_64t_1(void *); 147 extern int __get_user_64t_2(void *); 148 extern int __get_user_64t_4(void *); 149 150 #define __GUP_CLOBBER_1 "lr", "cc" 151 #ifdef CONFIG_CPU_USE_DOMAINS 152 #define __GUP_CLOBBER_2 "ip", "lr", "cc" 153 #else 154 #define __GUP_CLOBBER_2 "lr", "cc" 155 #endif 156 #define __GUP_CLOBBER_4 "lr", "cc" 157 #define __GUP_CLOBBER_32t_8 "lr", "cc" 158 #define __GUP_CLOBBER_8 "lr", "cc" 159 160 #define __get_user_x(__r2, __p, __e, __l, __s) \ 161 __asm__ __volatile__ ( \ 162 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 163 __asmeq("%3", "r1") \ 164 "bl __get_user_" #__s \ 165 : "=&r" (__e), "=r" (__r2) \ 166 : "0" (__p), "r" (__l) \ 167 : __GUP_CLOBBER_##__s) 168 169 /* narrowing a double-word get into a single 32bit word register: */ 170 #ifdef __ARMEB__ 171 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 172 __get_user_x(__r2, __p, __e, __l, 32t_8) 173 #else 174 #define __get_user_x_32t __get_user_x 175 #endif 176 177 /* 178 * storing result into proper least significant word of 64bit target var, 179 * different only for big endian case where 64 bit __r2 lsw is r3: 180 */ 181 #ifdef __ARMEB__ 182 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 183 __asm__ __volatile__ ( \ 184 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 185 __asmeq("%3", "r1") \ 186 "bl __get_user_64t_" #__s \ 187 : "=&r" (__e), "=r" (__r2) \ 188 : "0" (__p), "r" (__l) \ 189 : __GUP_CLOBBER_##__s) 190 #else 191 #define __get_user_x_64t __get_user_x 192 #endif 193 194 195 #define __get_user_check(x, p) \ 196 ({ \ 197 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 198 register typeof(*(p)) __user *__p asm("r0") = (p); \ 199 register __inttype(x) __r2 asm("r2"); \ 200 register unsigned long __l asm("r1") = __limit; \ 201 register int __e asm("r0"); \ 202 unsigned int __ua_flags = uaccess_save_and_enable(); \ 203 switch (sizeof(*(__p))) { \ 204 case 1: \ 205 if (sizeof((x)) >= 8) \ 206 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 207 else \ 208 __get_user_x(__r2, __p, __e, __l, 1); \ 209 break; \ 210 case 2: \ 211 if (sizeof((x)) >= 8) \ 212 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 213 else \ 214 __get_user_x(__r2, __p, __e, __l, 2); \ 215 break; \ 216 case 4: \ 217 if (sizeof((x)) >= 8) \ 218 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 219 else \ 220 __get_user_x(__r2, __p, __e, __l, 4); \ 221 break; \ 222 case 8: \ 223 if (sizeof((x)) < 8) \ 224 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 225 else \ 226 __get_user_x(__r2, __p, __e, __l, 8); \ 227 break; \ 228 default: __e = __get_user_bad(); break; \ 229 } \ 230 uaccess_restore(__ua_flags); \ 231 x = (typeof(*(p))) __r2; \ 232 __e; \ 233 }) 234 235 #define get_user(x, p) \ 236 ({ \ 237 might_fault(); \ 238 __get_user_check(x, p); \ 239 }) 240 241 extern int __put_user_1(void *, unsigned int); 242 extern int __put_user_2(void *, unsigned int); 243 extern int __put_user_4(void *, unsigned int); 244 extern int __put_user_8(void *, unsigned long long); 245 246 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 247 ({ \ 248 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 249 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 250 register const void __user *__p asm("r0") = __ptr; \ 251 register unsigned long __l asm("r1") = __limit; \ 252 register int __e asm("r0"); \ 253 __asm__ __volatile__ ( \ 254 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 255 __asmeq("%3", "r1") \ 256 "bl __put_user_" #__s \ 257 : "=&r" (__e) \ 258 : "0" (__p), "r" (__r2), "r" (__l) \ 259 : "ip", "lr", "cc"); \ 260 __err = __e; \ 261 }) 262 263 #else /* CONFIG_MMU */ 264 265 /* 266 * uClinux has only one addr space, so has simplified address limits. 267 */ 268 #define USER_DS KERNEL_DS 269 270 #define uaccess_kernel() (true) 271 #define __addr_ok(addr) ((void)(addr), 1) 272 #define __range_ok(addr, size) ((void)(addr), 0) 273 #define get_fs() (KERNEL_DS) 274 275 static inline void set_fs(mm_segment_t fs) 276 { 277 } 278 279 #define get_user(x, p) __get_user(x, p) 280 #define __put_user_check __put_user_nocheck 281 282 #endif /* CONFIG_MMU */ 283 284 #define access_ok(addr, size) (__range_ok(addr, size) == 0) 285 286 #define user_addr_max() \ 287 (uaccess_kernel() ? ~0UL : get_fs()) 288 289 #ifdef CONFIG_CPU_SPECTRE 290 /* 291 * When mitigating Spectre variant 1, it is not worth fixing the non- 292 * verifying accessors, because we need to add verification of the 293 * address space there. Force these to use the standard get_user() 294 * version instead. 295 */ 296 #define __get_user(x, ptr) get_user(x, ptr) 297 #else 298 299 /* 300 * The "__xxx" versions of the user access functions do not verify the 301 * address space - it must have been done previously with a separate 302 * "access_ok()" call. 303 * 304 * The "xxx_error" versions set the third argument to EFAULT if an 305 * error occurs, and leave it unchanged on success. Note that these 306 * versions are void (ie, don't return a value as such). 307 */ 308 #define __get_user(x, ptr) \ 309 ({ \ 310 long __gu_err = 0; \ 311 __get_user_err((x), (ptr), __gu_err); \ 312 __gu_err; \ 313 }) 314 315 #define __get_user_err(x, ptr, err) \ 316 do { \ 317 unsigned long __gu_addr = (unsigned long)(ptr); \ 318 unsigned long __gu_val; \ 319 unsigned int __ua_flags; \ 320 __chk_user_ptr(ptr); \ 321 might_fault(); \ 322 __ua_flags = uaccess_save_and_enable(); \ 323 switch (sizeof(*(ptr))) { \ 324 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \ 325 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \ 326 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \ 327 default: (__gu_val) = __get_user_bad(); \ 328 } \ 329 uaccess_restore(__ua_flags); \ 330 (x) = (__typeof__(*(ptr)))__gu_val; \ 331 } while (0) 332 333 #define __get_user_asm(x, addr, err, instr) \ 334 __asm__ __volatile__( \ 335 "1: " TUSER(instr) " %1, [%2], #0\n" \ 336 "2:\n" \ 337 " .pushsection .text.fixup,\"ax\"\n" \ 338 " .align 2\n" \ 339 "3: mov %0, %3\n" \ 340 " mov %1, #0\n" \ 341 " b 2b\n" \ 342 " .popsection\n" \ 343 " .pushsection __ex_table,\"a\"\n" \ 344 " .align 3\n" \ 345 " .long 1b, 3b\n" \ 346 " .popsection" \ 347 : "+r" (err), "=&r" (x) \ 348 : "r" (addr), "i" (-EFAULT) \ 349 : "cc") 350 351 #define __get_user_asm_byte(x, addr, err) \ 352 __get_user_asm(x, addr, err, ldrb) 353 354 #if __LINUX_ARM_ARCH__ >= 6 355 356 #define __get_user_asm_half(x, addr, err) \ 357 __get_user_asm(x, addr, err, ldrh) 358 359 #else 360 361 #ifndef __ARMEB__ 362 #define __get_user_asm_half(x, __gu_addr, err) \ 363 ({ \ 364 unsigned long __b1, __b2; \ 365 __get_user_asm_byte(__b1, __gu_addr, err); \ 366 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 367 (x) = __b1 | (__b2 << 8); \ 368 }) 369 #else 370 #define __get_user_asm_half(x, __gu_addr, err) \ 371 ({ \ 372 unsigned long __b1, __b2; \ 373 __get_user_asm_byte(__b1, __gu_addr, err); \ 374 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 375 (x) = (__b1 << 8) | __b2; \ 376 }) 377 #endif 378 379 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 380 381 #define __get_user_asm_word(x, addr, err) \ 382 __get_user_asm(x, addr, err, ldr) 383 #endif 384 385 386 #define __put_user_switch(x, ptr, __err, __fn) \ 387 do { \ 388 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 389 __typeof__(*(ptr)) __pu_val = (x); \ 390 unsigned int __ua_flags; \ 391 might_fault(); \ 392 __ua_flags = uaccess_save_and_enable(); \ 393 switch (sizeof(*(ptr))) { \ 394 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 395 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 396 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 397 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 398 default: __err = __put_user_bad(); break; \ 399 } \ 400 uaccess_restore(__ua_flags); \ 401 } while (0) 402 403 #define put_user(x, ptr) \ 404 ({ \ 405 int __pu_err = 0; \ 406 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 407 __pu_err; \ 408 }) 409 410 #ifdef CONFIG_CPU_SPECTRE 411 /* 412 * When mitigating Spectre variant 1.1, all accessors need to include 413 * verification of the address space. 414 */ 415 #define __put_user(x, ptr) put_user(x, ptr) 416 417 #else 418 #define __put_user(x, ptr) \ 419 ({ \ 420 long __pu_err = 0; \ 421 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 422 __pu_err; \ 423 }) 424 425 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 426 do { \ 427 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 428 __put_user_nocheck_##__size(x, __pu_addr, __err); \ 429 } while (0) 430 431 #define __put_user_nocheck_1 __put_user_asm_byte 432 #define __put_user_nocheck_2 __put_user_asm_half 433 #define __put_user_nocheck_4 __put_user_asm_word 434 #define __put_user_nocheck_8 __put_user_asm_dword 435 436 #define __put_user_asm(x, __pu_addr, err, instr) \ 437 __asm__ __volatile__( \ 438 "1: " TUSER(instr) " %1, [%2], #0\n" \ 439 "2:\n" \ 440 " .pushsection .text.fixup,\"ax\"\n" \ 441 " .align 2\n" \ 442 "3: mov %0, %3\n" \ 443 " b 2b\n" \ 444 " .popsection\n" \ 445 " .pushsection __ex_table,\"a\"\n" \ 446 " .align 3\n" \ 447 " .long 1b, 3b\n" \ 448 " .popsection" \ 449 : "+r" (err) \ 450 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 451 : "cc") 452 453 #define __put_user_asm_byte(x, __pu_addr, err) \ 454 __put_user_asm(x, __pu_addr, err, strb) 455 456 #if __LINUX_ARM_ARCH__ >= 6 457 458 #define __put_user_asm_half(x, __pu_addr, err) \ 459 __put_user_asm(x, __pu_addr, err, strh) 460 461 #else 462 463 #ifndef __ARMEB__ 464 #define __put_user_asm_half(x, __pu_addr, err) \ 465 ({ \ 466 unsigned long __temp = (__force unsigned long)(x); \ 467 __put_user_asm_byte(__temp, __pu_addr, err); \ 468 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \ 469 }) 470 #else 471 #define __put_user_asm_half(x, __pu_addr, err) \ 472 ({ \ 473 unsigned long __temp = (__force unsigned long)(x); \ 474 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \ 475 __put_user_asm_byte(__temp, __pu_addr + 1, err); \ 476 }) 477 #endif 478 479 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 480 481 #define __put_user_asm_word(x, __pu_addr, err) \ 482 __put_user_asm(x, __pu_addr, err, str) 483 484 #ifndef __ARMEB__ 485 #define __reg_oper0 "%R2" 486 #define __reg_oper1 "%Q2" 487 #else 488 #define __reg_oper0 "%Q2" 489 #define __reg_oper1 "%R2" 490 #endif 491 492 #define __put_user_asm_dword(x, __pu_addr, err) \ 493 __asm__ __volatile__( \ 494 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \ 495 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \ 496 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \ 497 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \ 498 "3:\n" \ 499 " .pushsection .text.fixup,\"ax\"\n" \ 500 " .align 2\n" \ 501 "4: mov %0, %3\n" \ 502 " b 3b\n" \ 503 " .popsection\n" \ 504 " .pushsection __ex_table,\"a\"\n" \ 505 " .align 3\n" \ 506 " .long 1b, 4b\n" \ 507 " .long 2b, 4b\n" \ 508 " .popsection" \ 509 : "+r" (err), "+r" (__pu_addr) \ 510 : "r" (x), "i" (-EFAULT) \ 511 : "cc") 512 513 #endif /* !CONFIG_CPU_SPECTRE */ 514 515 #ifdef CONFIG_MMU 516 extern unsigned long __must_check 517 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 518 519 static inline unsigned long __must_check 520 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 521 { 522 unsigned int __ua_flags; 523 524 __ua_flags = uaccess_save_and_enable(); 525 n = arm_copy_from_user(to, from, n); 526 uaccess_restore(__ua_flags); 527 return n; 528 } 529 530 extern unsigned long __must_check 531 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 532 extern unsigned long __must_check 533 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 534 535 static inline unsigned long __must_check 536 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 537 { 538 #ifndef CONFIG_UACCESS_WITH_MEMCPY 539 unsigned int __ua_flags; 540 __ua_flags = uaccess_save_and_enable(); 541 n = arm_copy_to_user(to, from, n); 542 uaccess_restore(__ua_flags); 543 return n; 544 #else 545 return arm_copy_to_user(to, from, n); 546 #endif 547 } 548 549 extern unsigned long __must_check 550 arm_clear_user(void __user *addr, unsigned long n); 551 extern unsigned long __must_check 552 __clear_user_std(void __user *addr, unsigned long n); 553 554 static inline unsigned long __must_check 555 __clear_user(void __user *addr, unsigned long n) 556 { 557 unsigned int __ua_flags = uaccess_save_and_enable(); 558 n = arm_clear_user(addr, n); 559 uaccess_restore(__ua_flags); 560 return n; 561 } 562 563 #else 564 static inline unsigned long 565 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 566 { 567 memcpy(to, (const void __force *)from, n); 568 return 0; 569 } 570 static inline unsigned long 571 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 572 { 573 memcpy((void __force *)to, from, n); 574 return 0; 575 } 576 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 577 #endif 578 #define INLINE_COPY_TO_USER 579 #define INLINE_COPY_FROM_USER 580 581 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 582 { 583 if (access_ok(to, n)) 584 n = __clear_user(to, n); 585 return n; 586 } 587 588 /* These are from lib/ code, and use __get_user() and friends */ 589 extern long strncpy_from_user(char *dest, const char __user *src, long count); 590 591 extern __must_check long strnlen_user(const char __user *str, long n); 592 593 #endif /* _ASMARM_UACCESS_H */ 594