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/page.h> 13 #include <asm/domain.h> 14 #include <asm/unaligned.h> 15 #include <asm/unified.h> 16 #include <asm/compiler.h> 17 18 #include <asm/extable.h> 19 20 /* 21 * These two functions allow hooking accesses to userspace to increase 22 * system integrity by ensuring that the kernel can not inadvertantly 23 * perform such accesses (eg, via list poison values) which could then 24 * be exploited for priviledge escalation. 25 */ 26 static __always_inline unsigned int uaccess_save_and_enable(void) 27 { 28 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 29 unsigned int old_domain = get_domain(); 30 31 /* Set the current domain access to permit user accesses */ 32 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) | 33 domain_val(DOMAIN_USER, DOMAIN_CLIENT)); 34 35 return old_domain; 36 #else 37 return 0; 38 #endif 39 } 40 41 static __always_inline void uaccess_restore(unsigned int flags) 42 { 43 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 44 /* Restore the user access mask */ 45 set_domain(flags); 46 #endif 47 } 48 49 /* 50 * These two are intentionally not defined anywhere - if the kernel 51 * code generates any references to them, that's a bug. 52 */ 53 extern int __get_user_bad(void); 54 extern int __put_user_bad(void); 55 56 #ifdef CONFIG_MMU 57 58 /* 59 * This is a type: either unsigned long, if the argument fits into 60 * that type, or otherwise unsigned long long. 61 */ 62 #define __inttype(x) \ 63 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 64 65 /* 66 * Sanitise a uaccess pointer such that it becomes NULL if addr+size 67 * is above the current addr_limit. 68 */ 69 #define uaccess_mask_range_ptr(ptr, size) \ 70 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size)) 71 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, 72 size_t size) 73 { 74 void __user *safe_ptr = (void __user *)ptr; 75 unsigned long tmp; 76 77 asm volatile( 78 " .syntax unified\n" 79 " sub %1, %3, #1\n" 80 " subs %1, %1, %0\n" 81 " addhs %1, %1, #1\n" 82 " subshs %1, %1, %2\n" 83 " movlo %0, #0\n" 84 : "+r" (safe_ptr), "=&r" (tmp) 85 : "r" (size), "r" (TASK_SIZE) 86 : "cc"); 87 88 csdb(); 89 return safe_ptr; 90 } 91 92 /* 93 * Single-value transfer routines. They automatically use the right 94 * size if we just have the right pointer type. Note that the functions 95 * which read from user space (*get_*) need to take care not to leak 96 * kernel data even if the calling code is buggy and fails to check 97 * the return value. This means zeroing out the destination variable 98 * or buffer on error. Normally this is done out of line by the 99 * fixup code, but there are a few places where it intrudes on the 100 * main code path. When we only write to user space, there is no 101 * problem. 102 */ 103 extern int __get_user_1(void *); 104 extern int __get_user_2(void *); 105 extern int __get_user_4(void *); 106 extern int __get_user_32t_8(void *); 107 extern int __get_user_8(void *); 108 extern int __get_user_64t_1(void *); 109 extern int __get_user_64t_2(void *); 110 extern int __get_user_64t_4(void *); 111 112 #define __GUP_CLOBBER_1 "lr", "cc" 113 #ifdef CONFIG_CPU_USE_DOMAINS 114 #define __GUP_CLOBBER_2 "ip", "lr", "cc" 115 #else 116 #define __GUP_CLOBBER_2 "lr", "cc" 117 #endif 118 #define __GUP_CLOBBER_4 "lr", "cc" 119 #define __GUP_CLOBBER_32t_8 "lr", "cc" 120 #define __GUP_CLOBBER_8 "lr", "cc" 121 122 #define __get_user_x(__r2, __p, __e, __l, __s) \ 123 __asm__ __volatile__ ( \ 124 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 125 __asmeq("%3", "r1") \ 126 "bl __get_user_" #__s \ 127 : "=&r" (__e), "=r" (__r2) \ 128 : "0" (__p), "r" (__l) \ 129 : __GUP_CLOBBER_##__s) 130 131 /* narrowing a double-word get into a single 32bit word register: */ 132 #ifdef __ARMEB__ 133 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 134 __get_user_x(__r2, __p, __e, __l, 32t_8) 135 #else 136 #define __get_user_x_32t __get_user_x 137 #endif 138 139 /* 140 * storing result into proper least significant word of 64bit target var, 141 * different only for big endian case where 64 bit __r2 lsw is r3: 142 */ 143 #ifdef __ARMEB__ 144 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 145 __asm__ __volatile__ ( \ 146 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 147 __asmeq("%3", "r1") \ 148 "bl __get_user_64t_" #__s \ 149 : "=&r" (__e), "=r" (__r2) \ 150 : "0" (__p), "r" (__l) \ 151 : __GUP_CLOBBER_##__s) 152 #else 153 #define __get_user_x_64t __get_user_x 154 #endif 155 156 157 #define __get_user_check(x, p) \ 158 ({ \ 159 unsigned long __limit = TASK_SIZE - 1; \ 160 register typeof(*(p)) __user *__p asm("r0") = (p); \ 161 register __inttype(x) __r2 asm("r2"); \ 162 register unsigned long __l asm("r1") = __limit; \ 163 register int __e asm("r0"); \ 164 unsigned int __ua_flags = uaccess_save_and_enable(); \ 165 int __tmp_e; \ 166 switch (sizeof(*(__p))) { \ 167 case 1: \ 168 if (sizeof((x)) >= 8) \ 169 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 170 else \ 171 __get_user_x(__r2, __p, __e, __l, 1); \ 172 break; \ 173 case 2: \ 174 if (sizeof((x)) >= 8) \ 175 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 176 else \ 177 __get_user_x(__r2, __p, __e, __l, 2); \ 178 break; \ 179 case 4: \ 180 if (sizeof((x)) >= 8) \ 181 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 182 else \ 183 __get_user_x(__r2, __p, __e, __l, 4); \ 184 break; \ 185 case 8: \ 186 if (sizeof((x)) < 8) \ 187 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 188 else \ 189 __get_user_x(__r2, __p, __e, __l, 8); \ 190 break; \ 191 default: __e = __get_user_bad(); break; \ 192 } \ 193 __tmp_e = __e; \ 194 uaccess_restore(__ua_flags); \ 195 x = (typeof(*(p))) __r2; \ 196 __tmp_e; \ 197 }) 198 199 #define get_user(x, p) \ 200 ({ \ 201 might_fault(); \ 202 __get_user_check(x, p); \ 203 }) 204 205 extern int __put_user_1(void *, unsigned int); 206 extern int __put_user_2(void *, unsigned int); 207 extern int __put_user_4(void *, unsigned int); 208 extern int __put_user_8(void *, unsigned long long); 209 210 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 211 ({ \ 212 unsigned long __limit = TASK_SIZE - 1; \ 213 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 214 register const void __user *__p asm("r0") = __ptr; \ 215 register unsigned long __l asm("r1") = __limit; \ 216 register int __e asm("r0"); \ 217 __asm__ __volatile__ ( \ 218 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 219 __asmeq("%3", "r1") \ 220 "bl __put_user_" #__s \ 221 : "=&r" (__e) \ 222 : "0" (__p), "r" (__r2), "r" (__l) \ 223 : "ip", "lr", "cc"); \ 224 __err = __e; \ 225 }) 226 227 #else /* CONFIG_MMU */ 228 229 #define get_user(x, p) __get_user(x, p) 230 #define __put_user_check __put_user_nocheck 231 232 #endif /* CONFIG_MMU */ 233 234 #include <asm-generic/access_ok.h> 235 236 #ifdef CONFIG_CPU_SPECTRE 237 /* 238 * When mitigating Spectre variant 1, it is not worth fixing the non- 239 * verifying accessors, because we need to add verification of the 240 * address space there. Force these to use the standard get_user() 241 * version instead. 242 */ 243 #define __get_user(x, ptr) get_user(x, ptr) 244 #else 245 246 /* 247 * The "__xxx" versions of the user access functions do not verify the 248 * address space - it must have been done previously with a separate 249 * "access_ok()" call. 250 * 251 * The "xxx_error" versions set the third argument to EFAULT if an 252 * error occurs, and leave it unchanged on success. Note that these 253 * versions are void (ie, don't return a value as such). 254 */ 255 #define __get_user(x, ptr) \ 256 ({ \ 257 long __gu_err = 0; \ 258 __get_user_err((x), (ptr), __gu_err, TUSER()); \ 259 __gu_err; \ 260 }) 261 262 #define __get_user_err(x, ptr, err, __t) \ 263 do { \ 264 unsigned long __gu_addr = (unsigned long)(ptr); \ 265 unsigned long __gu_val; \ 266 unsigned int __ua_flags; \ 267 __chk_user_ptr(ptr); \ 268 might_fault(); \ 269 __ua_flags = uaccess_save_and_enable(); \ 270 switch (sizeof(*(ptr))) { \ 271 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \ 272 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \ 273 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \ 274 default: (__gu_val) = __get_user_bad(); \ 275 } \ 276 uaccess_restore(__ua_flags); \ 277 (x) = (__typeof__(*(ptr)))__gu_val; \ 278 } while (0) 279 #endif 280 281 #define __get_user_asm(x, addr, err, instr) \ 282 __asm__ __volatile__( \ 283 "1: " instr " %1, [%2], #0\n" \ 284 "2:\n" \ 285 " .pushsection .text.fixup,\"ax\"\n" \ 286 " .align 2\n" \ 287 "3: mov %0, %3\n" \ 288 " mov %1, #0\n" \ 289 " b 2b\n" \ 290 " .popsection\n" \ 291 " .pushsection __ex_table,\"a\"\n" \ 292 " .align 3\n" \ 293 " .long 1b, 3b\n" \ 294 " .popsection" \ 295 : "+r" (err), "=&r" (x) \ 296 : "r" (addr), "i" (-EFAULT) \ 297 : "cc") 298 299 #define __get_user_asm_byte(x, addr, err, __t) \ 300 __get_user_asm(x, addr, err, "ldrb" __t) 301 302 #if __LINUX_ARM_ARCH__ >= 6 303 304 #define __get_user_asm_half(x, addr, err, __t) \ 305 __get_user_asm(x, addr, err, "ldrh" __t) 306 307 #else 308 309 #ifndef __ARMEB__ 310 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 311 ({ \ 312 unsigned long __b1, __b2; \ 313 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 314 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 315 (x) = __b1 | (__b2 << 8); \ 316 }) 317 #else 318 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 319 ({ \ 320 unsigned long __b1, __b2; \ 321 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 322 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 323 (x) = (__b1 << 8) | __b2; \ 324 }) 325 #endif 326 327 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 328 329 #define __get_user_asm_word(x, addr, err, __t) \ 330 __get_user_asm(x, addr, err, "ldr" __t) 331 332 #define __put_user_switch(x, ptr, __err, __fn) \ 333 do { \ 334 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 335 __typeof__(*(ptr)) __pu_val = (x); \ 336 unsigned int __ua_flags; \ 337 might_fault(); \ 338 __ua_flags = uaccess_save_and_enable(); \ 339 switch (sizeof(*(ptr))) { \ 340 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 341 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 342 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 343 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 344 default: __err = __put_user_bad(); break; \ 345 } \ 346 uaccess_restore(__ua_flags); \ 347 } while (0) 348 349 #define put_user(x, ptr) \ 350 ({ \ 351 int __pu_err = 0; \ 352 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 353 __pu_err; \ 354 }) 355 356 #ifdef CONFIG_CPU_SPECTRE 357 /* 358 * When mitigating Spectre variant 1.1, all accessors need to include 359 * verification of the address space. 360 */ 361 #define __put_user(x, ptr) put_user(x, ptr) 362 363 #else 364 #define __put_user(x, ptr) \ 365 ({ \ 366 long __pu_err = 0; \ 367 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 368 __pu_err; \ 369 }) 370 371 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 372 do { \ 373 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 374 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\ 375 } while (0) 376 377 #define __put_user_nocheck_1 __put_user_asm_byte 378 #define __put_user_nocheck_2 __put_user_asm_half 379 #define __put_user_nocheck_4 __put_user_asm_word 380 #define __put_user_nocheck_8 __put_user_asm_dword 381 382 #endif /* !CONFIG_CPU_SPECTRE */ 383 384 #define __put_user_asm(x, __pu_addr, err, instr) \ 385 __asm__ __volatile__( \ 386 "1: " instr " %1, [%2], #0\n" \ 387 "2:\n" \ 388 " .pushsection .text.fixup,\"ax\"\n" \ 389 " .align 2\n" \ 390 "3: mov %0, %3\n" \ 391 " b 2b\n" \ 392 " .popsection\n" \ 393 " .pushsection __ex_table,\"a\"\n" \ 394 " .align 3\n" \ 395 " .long 1b, 3b\n" \ 396 " .popsection" \ 397 : "+r" (err) \ 398 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 399 : "cc") 400 401 #define __put_user_asm_byte(x, __pu_addr, err, __t) \ 402 __put_user_asm(x, __pu_addr, err, "strb" __t) 403 404 #if __LINUX_ARM_ARCH__ >= 6 405 406 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 407 __put_user_asm(x, __pu_addr, err, "strh" __t) 408 409 #else 410 411 #ifndef __ARMEB__ 412 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 413 ({ \ 414 unsigned long __temp = (__force unsigned long)(x); \ 415 __put_user_asm_byte(__temp, __pu_addr, err, __t); \ 416 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\ 417 }) 418 #else 419 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 420 ({ \ 421 unsigned long __temp = (__force unsigned long)(x); \ 422 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \ 423 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \ 424 }) 425 #endif 426 427 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 428 429 #define __put_user_asm_word(x, __pu_addr, err, __t) \ 430 __put_user_asm(x, __pu_addr, err, "str" __t) 431 432 #ifndef __ARMEB__ 433 #define __reg_oper0 "%R2" 434 #define __reg_oper1 "%Q2" 435 #else 436 #define __reg_oper0 "%Q2" 437 #define __reg_oper1 "%R2" 438 #endif 439 440 #define __put_user_asm_dword(x, __pu_addr, err, __t) \ 441 __asm__ __volatile__( \ 442 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \ 443 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \ 444 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \ 445 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \ 446 "3:\n" \ 447 " .pushsection .text.fixup,\"ax\"\n" \ 448 " .align 2\n" \ 449 "4: mov %0, %3\n" \ 450 " b 3b\n" \ 451 " .popsection\n" \ 452 " .pushsection __ex_table,\"a\"\n" \ 453 " .align 3\n" \ 454 " .long 1b, 4b\n" \ 455 " .long 2b, 4b\n" \ 456 " .popsection" \ 457 : "+r" (err), "+r" (__pu_addr) \ 458 : "r" (x), "i" (-EFAULT) \ 459 : "cc") 460 461 #define __get_kernel_nofault(dst, src, type, err_label) \ 462 do { \ 463 const type *__pk_ptr = (src); \ 464 unsigned long __src = (unsigned long)(__pk_ptr); \ 465 type __val; \ 466 int __err = 0; \ 467 switch (sizeof(type)) { \ 468 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \ 469 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \ 470 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \ 471 case 8: { \ 472 u32 *__v32 = (u32*)&__val; \ 473 __get_user_asm_word(__v32[0], __src, __err, ""); \ 474 if (__err) \ 475 break; \ 476 __get_user_asm_word(__v32[1], __src+4, __err, ""); \ 477 break; \ 478 } \ 479 default: __err = __get_user_bad(); break; \ 480 } \ 481 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) \ 482 put_unaligned(__val, (type *)(dst)); \ 483 else \ 484 *(type *)(dst) = __val; /* aligned by caller */ \ 485 if (__err) \ 486 goto err_label; \ 487 } while (0) 488 489 #define __put_kernel_nofault(dst, src, type, err_label) \ 490 do { \ 491 const type *__pk_ptr = (dst); \ 492 unsigned long __dst = (unsigned long)__pk_ptr; \ 493 int __err = 0; \ 494 type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \ 495 ? get_unaligned((type *)(src)) \ 496 : *(type *)(src); /* aligned by caller */ \ 497 switch (sizeof(type)) { \ 498 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \ 499 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \ 500 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \ 501 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \ 502 default: __err = __put_user_bad(); break; \ 503 } \ 504 if (__err) \ 505 goto err_label; \ 506 } while (0) 507 508 #ifdef CONFIG_MMU 509 extern unsigned long __must_check 510 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 511 512 static inline unsigned long __must_check 513 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 514 { 515 unsigned int __ua_flags; 516 517 __ua_flags = uaccess_save_and_enable(); 518 n = arm_copy_from_user(to, from, n); 519 uaccess_restore(__ua_flags); 520 return n; 521 } 522 523 extern unsigned long __must_check 524 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 525 extern unsigned long __must_check 526 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 527 528 static inline unsigned long __must_check 529 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 530 { 531 #ifndef CONFIG_UACCESS_WITH_MEMCPY 532 unsigned int __ua_flags; 533 __ua_flags = uaccess_save_and_enable(); 534 n = arm_copy_to_user(to, from, n); 535 uaccess_restore(__ua_flags); 536 return n; 537 #else 538 return arm_copy_to_user(to, from, n); 539 #endif 540 } 541 542 extern unsigned long __must_check 543 arm_clear_user(void __user *addr, unsigned long n); 544 extern unsigned long __must_check 545 __clear_user_std(void __user *addr, unsigned long n); 546 547 static inline unsigned long __must_check 548 __clear_user(void __user *addr, unsigned long n) 549 { 550 unsigned int __ua_flags = uaccess_save_and_enable(); 551 n = arm_clear_user(addr, n); 552 uaccess_restore(__ua_flags); 553 return n; 554 } 555 556 #else 557 static inline unsigned long 558 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 559 { 560 memcpy(to, (const void __force *)from, n); 561 return 0; 562 } 563 static inline unsigned long 564 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 565 { 566 memcpy((void __force *)to, from, n); 567 return 0; 568 } 569 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 570 #endif 571 #define INLINE_COPY_TO_USER 572 #define INLINE_COPY_FROM_USER 573 574 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 575 { 576 if (access_ok(to, n)) 577 n = __clear_user(to, n); 578 return n; 579 } 580 581 /* These are from lib/ code, and use __get_user() and friends */ 582 extern long strncpy_from_user(char *dest, const char __user *src, long count); 583 584 extern __must_check long strnlen_user(const char __user *str, long n); 585 586 #endif /* _ASMARM_UACCESS_H */ 587