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 #ifdef CONFIG_MMU 56 57 /* 58 * We use 33-bit arithmetic here. Success returns zero, failure returns 59 * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS, 60 * so this will always return success in that case. 61 */ 62 #define __range_ok(addr, size) ({ \ 63 unsigned long flag, roksum; \ 64 __chk_user_ptr(addr); \ 65 __asm__(".syntax unified\n" \ 66 "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \ 67 : "=&r" (flag), "=&r" (roksum) \ 68 : "r" (addr), "Ir" (size), "0" (TASK_SIZE) \ 69 : "cc"); \ 70 flag; }) 71 72 /* 73 * This is a type: either unsigned long, if the argument fits into 74 * that type, or otherwise unsigned long long. 75 */ 76 #define __inttype(x) \ 77 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 78 79 /* 80 * Sanitise a uaccess pointer such that it becomes NULL if addr+size 81 * is above the current addr_limit. 82 */ 83 #define uaccess_mask_range_ptr(ptr, size) \ 84 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size)) 85 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, 86 size_t size) 87 { 88 void __user *safe_ptr = (void __user *)ptr; 89 unsigned long tmp; 90 91 asm volatile( 92 " .syntax unified\n" 93 " sub %1, %3, #1\n" 94 " subs %1, %1, %0\n" 95 " addhs %1, %1, #1\n" 96 " subshs %1, %1, %2\n" 97 " movlo %0, #0\n" 98 : "+r" (safe_ptr), "=&r" (tmp) 99 : "r" (size), "r" (TASK_SIZE) 100 : "cc"); 101 102 csdb(); 103 return safe_ptr; 104 } 105 106 /* 107 * Single-value transfer routines. They automatically use the right 108 * size if we just have the right pointer type. Note that the functions 109 * which read from user space (*get_*) need to take care not to leak 110 * kernel data even if the calling code is buggy and fails to check 111 * the return value. This means zeroing out the destination variable 112 * or buffer on error. Normally this is done out of line by the 113 * fixup code, but there are a few places where it intrudes on the 114 * main code path. When we only write to user space, there is no 115 * problem. 116 */ 117 extern int __get_user_1(void *); 118 extern int __get_user_2(void *); 119 extern int __get_user_4(void *); 120 extern int __get_user_32t_8(void *); 121 extern int __get_user_8(void *); 122 extern int __get_user_64t_1(void *); 123 extern int __get_user_64t_2(void *); 124 extern int __get_user_64t_4(void *); 125 126 #define __GUP_CLOBBER_1 "lr", "cc" 127 #ifdef CONFIG_CPU_USE_DOMAINS 128 #define __GUP_CLOBBER_2 "ip", "lr", "cc" 129 #else 130 #define __GUP_CLOBBER_2 "lr", "cc" 131 #endif 132 #define __GUP_CLOBBER_4 "lr", "cc" 133 #define __GUP_CLOBBER_32t_8 "lr", "cc" 134 #define __GUP_CLOBBER_8 "lr", "cc" 135 136 #define __get_user_x(__r2, __p, __e, __l, __s) \ 137 __asm__ __volatile__ ( \ 138 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 139 __asmeq("%3", "r1") \ 140 "bl __get_user_" #__s \ 141 : "=&r" (__e), "=r" (__r2) \ 142 : "0" (__p), "r" (__l) \ 143 : __GUP_CLOBBER_##__s) 144 145 /* narrowing a double-word get into a single 32bit word register: */ 146 #ifdef __ARMEB__ 147 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 148 __get_user_x(__r2, __p, __e, __l, 32t_8) 149 #else 150 #define __get_user_x_32t __get_user_x 151 #endif 152 153 /* 154 * storing result into proper least significant word of 64bit target var, 155 * different only for big endian case where 64 bit __r2 lsw is r3: 156 */ 157 #ifdef __ARMEB__ 158 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 159 __asm__ __volatile__ ( \ 160 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 161 __asmeq("%3", "r1") \ 162 "bl __get_user_64t_" #__s \ 163 : "=&r" (__e), "=r" (__r2) \ 164 : "0" (__p), "r" (__l) \ 165 : __GUP_CLOBBER_##__s) 166 #else 167 #define __get_user_x_64t __get_user_x 168 #endif 169 170 171 #define __get_user_check(x, p) \ 172 ({ \ 173 unsigned long __limit = TASK_SIZE - 1; \ 174 register typeof(*(p)) __user *__p asm("r0") = (p); \ 175 register __inttype(x) __r2 asm("r2"); \ 176 register unsigned long __l asm("r1") = __limit; \ 177 register int __e asm("r0"); \ 178 unsigned int __ua_flags = uaccess_save_and_enable(); \ 179 switch (sizeof(*(__p))) { \ 180 case 1: \ 181 if (sizeof((x)) >= 8) \ 182 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 183 else \ 184 __get_user_x(__r2, __p, __e, __l, 1); \ 185 break; \ 186 case 2: \ 187 if (sizeof((x)) >= 8) \ 188 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 189 else \ 190 __get_user_x(__r2, __p, __e, __l, 2); \ 191 break; \ 192 case 4: \ 193 if (sizeof((x)) >= 8) \ 194 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 195 else \ 196 __get_user_x(__r2, __p, __e, __l, 4); \ 197 break; \ 198 case 8: \ 199 if (sizeof((x)) < 8) \ 200 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 201 else \ 202 __get_user_x(__r2, __p, __e, __l, 8); \ 203 break; \ 204 default: __e = __get_user_bad(); break; \ 205 } \ 206 uaccess_restore(__ua_flags); \ 207 x = (typeof(*(p))) __r2; \ 208 __e; \ 209 }) 210 211 #define get_user(x, p) \ 212 ({ \ 213 might_fault(); \ 214 __get_user_check(x, p); \ 215 }) 216 217 extern int __put_user_1(void *, unsigned int); 218 extern int __put_user_2(void *, unsigned int); 219 extern int __put_user_4(void *, unsigned int); 220 extern int __put_user_8(void *, unsigned long long); 221 222 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 223 ({ \ 224 unsigned long __limit = TASK_SIZE - 1; \ 225 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 226 register const void __user *__p asm("r0") = __ptr; \ 227 register unsigned long __l asm("r1") = __limit; \ 228 register int __e asm("r0"); \ 229 __asm__ __volatile__ ( \ 230 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 231 __asmeq("%3", "r1") \ 232 "bl __put_user_" #__s \ 233 : "=&r" (__e) \ 234 : "0" (__p), "r" (__r2), "r" (__l) \ 235 : "ip", "lr", "cc"); \ 236 __err = __e; \ 237 }) 238 239 #else /* CONFIG_MMU */ 240 241 #define __addr_ok(addr) ((void)(addr), 1) 242 #define __range_ok(addr, size) ((void)(addr), 0) 243 244 #define get_user(x, p) __get_user(x, p) 245 #define __put_user_check __put_user_nocheck 246 247 #endif /* CONFIG_MMU */ 248 249 #define access_ok(addr, size) (__range_ok(addr, size) == 0) 250 251 #ifdef CONFIG_CPU_SPECTRE 252 /* 253 * When mitigating Spectre variant 1, it is not worth fixing the non- 254 * verifying accessors, because we need to add verification of the 255 * address space there. Force these to use the standard get_user() 256 * version instead. 257 */ 258 #define __get_user(x, ptr) get_user(x, ptr) 259 #else 260 261 /* 262 * The "__xxx" versions of the user access functions do not verify the 263 * address space - it must have been done previously with a separate 264 * "access_ok()" call. 265 * 266 * The "xxx_error" versions set the third argument to EFAULT if an 267 * error occurs, and leave it unchanged on success. Note that these 268 * versions are void (ie, don't return a value as such). 269 */ 270 #define __get_user(x, ptr) \ 271 ({ \ 272 long __gu_err = 0; \ 273 __get_user_err((x), (ptr), __gu_err, TUSER()); \ 274 __gu_err; \ 275 }) 276 277 #define __get_user_err(x, ptr, err, __t) \ 278 do { \ 279 unsigned long __gu_addr = (unsigned long)(ptr); \ 280 unsigned long __gu_val; \ 281 unsigned int __ua_flags; \ 282 __chk_user_ptr(ptr); \ 283 might_fault(); \ 284 __ua_flags = uaccess_save_and_enable(); \ 285 switch (sizeof(*(ptr))) { \ 286 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \ 287 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \ 288 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \ 289 default: (__gu_val) = __get_user_bad(); \ 290 } \ 291 uaccess_restore(__ua_flags); \ 292 (x) = (__typeof__(*(ptr)))__gu_val; \ 293 } while (0) 294 #endif 295 296 #define __get_user_asm(x, addr, err, instr) \ 297 __asm__ __volatile__( \ 298 "1: " instr " %1, [%2], #0\n" \ 299 "2:\n" \ 300 " .pushsection .text.fixup,\"ax\"\n" \ 301 " .align 2\n" \ 302 "3: mov %0, %3\n" \ 303 " mov %1, #0\n" \ 304 " b 2b\n" \ 305 " .popsection\n" \ 306 " .pushsection __ex_table,\"a\"\n" \ 307 " .align 3\n" \ 308 " .long 1b, 3b\n" \ 309 " .popsection" \ 310 : "+r" (err), "=&r" (x) \ 311 : "r" (addr), "i" (-EFAULT) \ 312 : "cc") 313 314 #define __get_user_asm_byte(x, addr, err, __t) \ 315 __get_user_asm(x, addr, err, "ldrb" __t) 316 317 #if __LINUX_ARM_ARCH__ >= 6 318 319 #define __get_user_asm_half(x, addr, err, __t) \ 320 __get_user_asm(x, addr, err, "ldrh" __t) 321 322 #else 323 324 #ifndef __ARMEB__ 325 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 326 ({ \ 327 unsigned long __b1, __b2; \ 328 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 329 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 330 (x) = __b1 | (__b2 << 8); \ 331 }) 332 #else 333 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 334 ({ \ 335 unsigned long __b1, __b2; \ 336 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 337 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 338 (x) = (__b1 << 8) | __b2; \ 339 }) 340 #endif 341 342 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 343 344 #define __get_user_asm_word(x, addr, err, __t) \ 345 __get_user_asm(x, addr, err, "ldr" __t) 346 347 #define __put_user_switch(x, ptr, __err, __fn) \ 348 do { \ 349 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 350 __typeof__(*(ptr)) __pu_val = (x); \ 351 unsigned int __ua_flags; \ 352 might_fault(); \ 353 __ua_flags = uaccess_save_and_enable(); \ 354 switch (sizeof(*(ptr))) { \ 355 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 356 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 357 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 358 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 359 default: __err = __put_user_bad(); break; \ 360 } \ 361 uaccess_restore(__ua_flags); \ 362 } while (0) 363 364 #define put_user(x, ptr) \ 365 ({ \ 366 int __pu_err = 0; \ 367 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 368 __pu_err; \ 369 }) 370 371 #ifdef CONFIG_CPU_SPECTRE 372 /* 373 * When mitigating Spectre variant 1.1, all accessors need to include 374 * verification of the address space. 375 */ 376 #define __put_user(x, ptr) put_user(x, ptr) 377 378 #else 379 #define __put_user(x, ptr) \ 380 ({ \ 381 long __pu_err = 0; \ 382 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 383 __pu_err; \ 384 }) 385 386 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 387 do { \ 388 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 389 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\ 390 } while (0) 391 392 #define __put_user_nocheck_1 __put_user_asm_byte 393 #define __put_user_nocheck_2 __put_user_asm_half 394 #define __put_user_nocheck_4 __put_user_asm_word 395 #define __put_user_nocheck_8 __put_user_asm_dword 396 397 #endif /* !CONFIG_CPU_SPECTRE */ 398 399 #define __put_user_asm(x, __pu_addr, err, instr) \ 400 __asm__ __volatile__( \ 401 "1: " instr " %1, [%2], #0\n" \ 402 "2:\n" \ 403 " .pushsection .text.fixup,\"ax\"\n" \ 404 " .align 2\n" \ 405 "3: mov %0, %3\n" \ 406 " b 2b\n" \ 407 " .popsection\n" \ 408 " .pushsection __ex_table,\"a\"\n" \ 409 " .align 3\n" \ 410 " .long 1b, 3b\n" \ 411 " .popsection" \ 412 : "+r" (err) \ 413 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 414 : "cc") 415 416 #define __put_user_asm_byte(x, __pu_addr, err, __t) \ 417 __put_user_asm(x, __pu_addr, err, "strb" __t) 418 419 #if __LINUX_ARM_ARCH__ >= 6 420 421 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 422 __put_user_asm(x, __pu_addr, err, "strh" __t) 423 424 #else 425 426 #ifndef __ARMEB__ 427 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 428 ({ \ 429 unsigned long __temp = (__force unsigned long)(x); \ 430 __put_user_asm_byte(__temp, __pu_addr, err, __t); \ 431 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\ 432 }) 433 #else 434 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 435 ({ \ 436 unsigned long __temp = (__force unsigned long)(x); \ 437 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \ 438 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \ 439 }) 440 #endif 441 442 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 443 444 #define __put_user_asm_word(x, __pu_addr, err, __t) \ 445 __put_user_asm(x, __pu_addr, err, "str" __t) 446 447 #ifndef __ARMEB__ 448 #define __reg_oper0 "%R2" 449 #define __reg_oper1 "%Q2" 450 #else 451 #define __reg_oper0 "%Q2" 452 #define __reg_oper1 "%R2" 453 #endif 454 455 #define __put_user_asm_dword(x, __pu_addr, err, __t) \ 456 __asm__ __volatile__( \ 457 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \ 458 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \ 459 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \ 460 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \ 461 "3:\n" \ 462 " .pushsection .text.fixup,\"ax\"\n" \ 463 " .align 2\n" \ 464 "4: mov %0, %3\n" \ 465 " b 3b\n" \ 466 " .popsection\n" \ 467 " .pushsection __ex_table,\"a\"\n" \ 468 " .align 3\n" \ 469 " .long 1b, 4b\n" \ 470 " .long 2b, 4b\n" \ 471 " .popsection" \ 472 : "+r" (err), "+r" (__pu_addr) \ 473 : "r" (x), "i" (-EFAULT) \ 474 : "cc") 475 476 #define HAVE_GET_KERNEL_NOFAULT 477 478 #define __get_kernel_nofault(dst, src, type, err_label) \ 479 do { \ 480 const type *__pk_ptr = (src); \ 481 unsigned long __src = (unsigned long)(__pk_ptr); \ 482 type __val; \ 483 int __err = 0; \ 484 switch (sizeof(type)) { \ 485 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \ 486 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \ 487 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \ 488 case 8: { \ 489 u32 *__v32 = (u32*)&__val; \ 490 __get_user_asm_word(__v32[0], __src, __err, ""); \ 491 if (__err) \ 492 break; \ 493 __get_user_asm_word(__v32[1], __src+4, __err, ""); \ 494 break; \ 495 } \ 496 default: __err = __get_user_bad(); break; \ 497 } \ 498 *(type *)(dst) = __val; \ 499 if (__err) \ 500 goto err_label; \ 501 } while (0) 502 503 #define __put_kernel_nofault(dst, src, type, err_label) \ 504 do { \ 505 const type *__pk_ptr = (dst); \ 506 unsigned long __dst = (unsigned long)__pk_ptr; \ 507 int __err = 0; \ 508 type __val = *(type *)src; \ 509 switch (sizeof(type)) { \ 510 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \ 511 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \ 512 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \ 513 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \ 514 default: __err = __put_user_bad(); break; \ 515 } \ 516 if (__err) \ 517 goto err_label; \ 518 } while (0) 519 520 #ifdef CONFIG_MMU 521 extern unsigned long __must_check 522 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 523 524 static inline unsigned long __must_check 525 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 526 { 527 unsigned int __ua_flags; 528 529 __ua_flags = uaccess_save_and_enable(); 530 n = arm_copy_from_user(to, from, n); 531 uaccess_restore(__ua_flags); 532 return n; 533 } 534 535 extern unsigned long __must_check 536 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 537 extern unsigned long __must_check 538 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 539 540 static inline unsigned long __must_check 541 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 542 { 543 #ifndef CONFIG_UACCESS_WITH_MEMCPY 544 unsigned int __ua_flags; 545 __ua_flags = uaccess_save_and_enable(); 546 n = arm_copy_to_user(to, from, n); 547 uaccess_restore(__ua_flags); 548 return n; 549 #else 550 return arm_copy_to_user(to, from, n); 551 #endif 552 } 553 554 extern unsigned long __must_check 555 arm_clear_user(void __user *addr, unsigned long n); 556 extern unsigned long __must_check 557 __clear_user_std(void __user *addr, unsigned long n); 558 559 static inline unsigned long __must_check 560 __clear_user(void __user *addr, unsigned long n) 561 { 562 unsigned int __ua_flags = uaccess_save_and_enable(); 563 n = arm_clear_user(addr, n); 564 uaccess_restore(__ua_flags); 565 return n; 566 } 567 568 #else 569 static inline unsigned long 570 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 571 { 572 memcpy(to, (const void __force *)from, n); 573 return 0; 574 } 575 static inline unsigned long 576 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 577 { 578 memcpy((void __force *)to, from, n); 579 return 0; 580 } 581 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 582 #endif 583 #define INLINE_COPY_TO_USER 584 #define INLINE_COPY_FROM_USER 585 586 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 587 { 588 if (access_ok(to, n)) 589 n = __clear_user(to, n); 590 return n; 591 } 592 593 /* These are from lib/ code, and use __get_user() and friends */ 594 extern long strncpy_from_user(char *dest, const char __user *src, long count); 595 596 extern __must_check long strnlen_user(const char __user *str, long n); 597 598 #endif /* _ASMARM_UACCESS_H */ 599