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 int __tmp_e; \ 180 switch (sizeof(*(__p))) { \ 181 case 1: \ 182 if (sizeof((x)) >= 8) \ 183 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 184 else \ 185 __get_user_x(__r2, __p, __e, __l, 1); \ 186 break; \ 187 case 2: \ 188 if (sizeof((x)) >= 8) \ 189 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 190 else \ 191 __get_user_x(__r2, __p, __e, __l, 2); \ 192 break; \ 193 case 4: \ 194 if (sizeof((x)) >= 8) \ 195 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 196 else \ 197 __get_user_x(__r2, __p, __e, __l, 4); \ 198 break; \ 199 case 8: \ 200 if (sizeof((x)) < 8) \ 201 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 202 else \ 203 __get_user_x(__r2, __p, __e, __l, 8); \ 204 break; \ 205 default: __e = __get_user_bad(); break; \ 206 } \ 207 __tmp_e = __e; \ 208 uaccess_restore(__ua_flags); \ 209 x = (typeof(*(p))) __r2; \ 210 __tmp_e; \ 211 }) 212 213 #define get_user(x, p) \ 214 ({ \ 215 might_fault(); \ 216 __get_user_check(x, p); \ 217 }) 218 219 extern int __put_user_1(void *, unsigned int); 220 extern int __put_user_2(void *, unsigned int); 221 extern int __put_user_4(void *, unsigned int); 222 extern int __put_user_8(void *, unsigned long long); 223 224 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 225 ({ \ 226 unsigned long __limit = TASK_SIZE - 1; \ 227 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 228 register const void __user *__p asm("r0") = __ptr; \ 229 register unsigned long __l asm("r1") = __limit; \ 230 register int __e asm("r0"); \ 231 __asm__ __volatile__ ( \ 232 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 233 __asmeq("%3", "r1") \ 234 "bl __put_user_" #__s \ 235 : "=&r" (__e) \ 236 : "0" (__p), "r" (__r2), "r" (__l) \ 237 : "ip", "lr", "cc"); \ 238 __err = __e; \ 239 }) 240 241 #else /* CONFIG_MMU */ 242 243 #define __addr_ok(addr) ((void)(addr), 1) 244 #define __range_ok(addr, size) ((void)(addr), 0) 245 246 #define get_user(x, p) __get_user(x, p) 247 #define __put_user_check __put_user_nocheck 248 249 #endif /* CONFIG_MMU */ 250 251 #define access_ok(addr, size) (__range_ok(addr, size) == 0) 252 253 #ifdef CONFIG_CPU_SPECTRE 254 /* 255 * When mitigating Spectre variant 1, it is not worth fixing the non- 256 * verifying accessors, because we need to add verification of the 257 * address space there. Force these to use the standard get_user() 258 * version instead. 259 */ 260 #define __get_user(x, ptr) get_user(x, ptr) 261 #else 262 263 /* 264 * The "__xxx" versions of the user access functions do not verify the 265 * address space - it must have been done previously with a separate 266 * "access_ok()" call. 267 * 268 * The "xxx_error" versions set the third argument to EFAULT if an 269 * error occurs, and leave it unchanged on success. Note that these 270 * versions are void (ie, don't return a value as such). 271 */ 272 #define __get_user(x, ptr) \ 273 ({ \ 274 long __gu_err = 0; \ 275 __get_user_err((x), (ptr), __gu_err, TUSER()); \ 276 __gu_err; \ 277 }) 278 279 #define __get_user_err(x, ptr, err, __t) \ 280 do { \ 281 unsigned long __gu_addr = (unsigned long)(ptr); \ 282 unsigned long __gu_val; \ 283 unsigned int __ua_flags; \ 284 __chk_user_ptr(ptr); \ 285 might_fault(); \ 286 __ua_flags = uaccess_save_and_enable(); \ 287 switch (sizeof(*(ptr))) { \ 288 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \ 289 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \ 290 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \ 291 default: (__gu_val) = __get_user_bad(); \ 292 } \ 293 uaccess_restore(__ua_flags); \ 294 (x) = (__typeof__(*(ptr)))__gu_val; \ 295 } while (0) 296 #endif 297 298 #define __get_user_asm(x, addr, err, instr) \ 299 __asm__ __volatile__( \ 300 "1: " instr " %1, [%2], #0\n" \ 301 "2:\n" \ 302 " .pushsection .text.fixup,\"ax\"\n" \ 303 " .align 2\n" \ 304 "3: mov %0, %3\n" \ 305 " mov %1, #0\n" \ 306 " b 2b\n" \ 307 " .popsection\n" \ 308 " .pushsection __ex_table,\"a\"\n" \ 309 " .align 3\n" \ 310 " .long 1b, 3b\n" \ 311 " .popsection" \ 312 : "+r" (err), "=&r" (x) \ 313 : "r" (addr), "i" (-EFAULT) \ 314 : "cc") 315 316 #define __get_user_asm_byte(x, addr, err, __t) \ 317 __get_user_asm(x, addr, err, "ldrb" __t) 318 319 #if __LINUX_ARM_ARCH__ >= 6 320 321 #define __get_user_asm_half(x, addr, err, __t) \ 322 __get_user_asm(x, addr, err, "ldrh" __t) 323 324 #else 325 326 #ifndef __ARMEB__ 327 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 328 ({ \ 329 unsigned long __b1, __b2; \ 330 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 331 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 332 (x) = __b1 | (__b2 << 8); \ 333 }) 334 #else 335 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 336 ({ \ 337 unsigned long __b1, __b2; \ 338 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 339 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 340 (x) = (__b1 << 8) | __b2; \ 341 }) 342 #endif 343 344 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 345 346 #define __get_user_asm_word(x, addr, err, __t) \ 347 __get_user_asm(x, addr, err, "ldr" __t) 348 349 #define __put_user_switch(x, ptr, __err, __fn) \ 350 do { \ 351 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 352 __typeof__(*(ptr)) __pu_val = (x); \ 353 unsigned int __ua_flags; \ 354 might_fault(); \ 355 __ua_flags = uaccess_save_and_enable(); \ 356 switch (sizeof(*(ptr))) { \ 357 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 358 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 359 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 360 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 361 default: __err = __put_user_bad(); break; \ 362 } \ 363 uaccess_restore(__ua_flags); \ 364 } while (0) 365 366 #define put_user(x, ptr) \ 367 ({ \ 368 int __pu_err = 0; \ 369 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 370 __pu_err; \ 371 }) 372 373 #ifdef CONFIG_CPU_SPECTRE 374 /* 375 * When mitigating Spectre variant 1.1, all accessors need to include 376 * verification of the address space. 377 */ 378 #define __put_user(x, ptr) put_user(x, ptr) 379 380 #else 381 #define __put_user(x, ptr) \ 382 ({ \ 383 long __pu_err = 0; \ 384 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 385 __pu_err; \ 386 }) 387 388 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 389 do { \ 390 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 391 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\ 392 } while (0) 393 394 #define __put_user_nocheck_1 __put_user_asm_byte 395 #define __put_user_nocheck_2 __put_user_asm_half 396 #define __put_user_nocheck_4 __put_user_asm_word 397 #define __put_user_nocheck_8 __put_user_asm_dword 398 399 #endif /* !CONFIG_CPU_SPECTRE */ 400 401 #define __put_user_asm(x, __pu_addr, err, instr) \ 402 __asm__ __volatile__( \ 403 "1: " instr " %1, [%2], #0\n" \ 404 "2:\n" \ 405 " .pushsection .text.fixup,\"ax\"\n" \ 406 " .align 2\n" \ 407 "3: mov %0, %3\n" \ 408 " b 2b\n" \ 409 " .popsection\n" \ 410 " .pushsection __ex_table,\"a\"\n" \ 411 " .align 3\n" \ 412 " .long 1b, 3b\n" \ 413 " .popsection" \ 414 : "+r" (err) \ 415 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 416 : "cc") 417 418 #define __put_user_asm_byte(x, __pu_addr, err, __t) \ 419 __put_user_asm(x, __pu_addr, err, "strb" __t) 420 421 #if __LINUX_ARM_ARCH__ >= 6 422 423 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 424 __put_user_asm(x, __pu_addr, err, "strh" __t) 425 426 #else 427 428 #ifndef __ARMEB__ 429 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 430 ({ \ 431 unsigned long __temp = (__force unsigned long)(x); \ 432 __put_user_asm_byte(__temp, __pu_addr, err, __t); \ 433 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\ 434 }) 435 #else 436 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 437 ({ \ 438 unsigned long __temp = (__force unsigned long)(x); \ 439 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \ 440 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \ 441 }) 442 #endif 443 444 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 445 446 #define __put_user_asm_word(x, __pu_addr, err, __t) \ 447 __put_user_asm(x, __pu_addr, err, "str" __t) 448 449 #ifndef __ARMEB__ 450 #define __reg_oper0 "%R2" 451 #define __reg_oper1 "%Q2" 452 #else 453 #define __reg_oper0 "%Q2" 454 #define __reg_oper1 "%R2" 455 #endif 456 457 #define __put_user_asm_dword(x, __pu_addr, err, __t) \ 458 __asm__ __volatile__( \ 459 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \ 460 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \ 461 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \ 462 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \ 463 "3:\n" \ 464 " .pushsection .text.fixup,\"ax\"\n" \ 465 " .align 2\n" \ 466 "4: mov %0, %3\n" \ 467 " b 3b\n" \ 468 " .popsection\n" \ 469 " .pushsection __ex_table,\"a\"\n" \ 470 " .align 3\n" \ 471 " .long 1b, 4b\n" \ 472 " .long 2b, 4b\n" \ 473 " .popsection" \ 474 : "+r" (err), "+r" (__pu_addr) \ 475 : "r" (x), "i" (-EFAULT) \ 476 : "cc") 477 478 #define HAVE_GET_KERNEL_NOFAULT 479 480 #define __get_kernel_nofault(dst, src, type, err_label) \ 481 do { \ 482 const type *__pk_ptr = (src); \ 483 unsigned long __src = (unsigned long)(__pk_ptr); \ 484 type __val; \ 485 int __err = 0; \ 486 switch (sizeof(type)) { \ 487 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \ 488 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \ 489 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \ 490 case 8: { \ 491 u32 *__v32 = (u32*)&__val; \ 492 __get_user_asm_word(__v32[0], __src, __err, ""); \ 493 if (__err) \ 494 break; \ 495 __get_user_asm_word(__v32[1], __src+4, __err, ""); \ 496 break; \ 497 } \ 498 default: __err = __get_user_bad(); break; \ 499 } \ 500 *(type *)(dst) = __val; \ 501 if (__err) \ 502 goto err_label; \ 503 } while (0) 504 505 #define __put_kernel_nofault(dst, src, type, err_label) \ 506 do { \ 507 const type *__pk_ptr = (dst); \ 508 unsigned long __dst = (unsigned long)__pk_ptr; \ 509 int __err = 0; \ 510 type __val = *(type *)src; \ 511 switch (sizeof(type)) { \ 512 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \ 513 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \ 514 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \ 515 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \ 516 default: __err = __put_user_bad(); break; \ 517 } \ 518 if (__err) \ 519 goto err_label; \ 520 } while (0) 521 522 #ifdef CONFIG_MMU 523 extern unsigned long __must_check 524 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 525 526 static inline unsigned long __must_check 527 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 528 { 529 unsigned int __ua_flags; 530 531 __ua_flags = uaccess_save_and_enable(); 532 n = arm_copy_from_user(to, from, n); 533 uaccess_restore(__ua_flags); 534 return n; 535 } 536 537 extern unsigned long __must_check 538 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 539 extern unsigned long __must_check 540 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 541 542 static inline unsigned long __must_check 543 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 544 { 545 #ifndef CONFIG_UACCESS_WITH_MEMCPY 546 unsigned int __ua_flags; 547 __ua_flags = uaccess_save_and_enable(); 548 n = arm_copy_to_user(to, from, n); 549 uaccess_restore(__ua_flags); 550 return n; 551 #else 552 return arm_copy_to_user(to, from, n); 553 #endif 554 } 555 556 extern unsigned long __must_check 557 arm_clear_user(void __user *addr, unsigned long n); 558 extern unsigned long __must_check 559 __clear_user_std(void __user *addr, unsigned long n); 560 561 static inline unsigned long __must_check 562 __clear_user(void __user *addr, unsigned long n) 563 { 564 unsigned int __ua_flags = uaccess_save_and_enable(); 565 n = arm_clear_user(addr, n); 566 uaccess_restore(__ua_flags); 567 return n; 568 } 569 570 #else 571 static inline unsigned long 572 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 573 { 574 memcpy(to, (const void __force *)from, n); 575 return 0; 576 } 577 static inline unsigned long 578 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 579 { 580 memcpy((void __force *)to, from, n); 581 return 0; 582 } 583 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 584 #endif 585 #define INLINE_COPY_TO_USER 586 #define INLINE_COPY_FROM_USER 587 588 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 589 { 590 if (access_ok(to, n)) 591 n = __clear_user(to, n); 592 return n; 593 } 594 595 /* These are from lib/ code, and use __get_user() and friends */ 596 extern long strncpy_from_user(char *dest, const char __user *src, long count); 597 598 extern __must_check long strnlen_user(const char __user *str, long n); 599 600 #endif /* _ASMARM_UACCESS_H */ 601