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/kernel.h> 12 #include <linux/string.h> 13 #include <asm/page.h> 14 #include <asm/domain.h> 15 #include <asm/unaligned.h> 16 #include <asm/unified.h> 17 #include <asm/compiler.h> 18 19 #include <asm/extable.h> 20 21 /* 22 * These two functions allow hooking accesses to userspace to increase 23 * system integrity by ensuring that the kernel can not inadvertantly 24 * perform such accesses (eg, via list poison values) which could then 25 * be exploited for priviledge escalation. 26 */ 27 static __always_inline unsigned int uaccess_save_and_enable(void) 28 { 29 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 30 unsigned int old_domain = get_domain(); 31 32 /* Set the current domain access to permit user accesses */ 33 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) | 34 domain_val(DOMAIN_USER, DOMAIN_CLIENT)); 35 36 return old_domain; 37 #else 38 return 0; 39 #endif 40 } 41 42 static __always_inline void uaccess_restore(unsigned int flags) 43 { 44 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 45 /* Restore the user access mask */ 46 set_domain(flags); 47 #endif 48 } 49 50 /* 51 * These two are intentionally not defined anywhere - if the kernel 52 * code generates any references to them, that's a bug. 53 */ 54 extern int __get_user_bad(void); 55 extern int __put_user_bad(void); 56 57 #ifdef CONFIG_MMU 58 59 /* 60 * This is a type: either unsigned long, if the argument fits into 61 * that type, or otherwise unsigned long long. 62 */ 63 #define __inttype(x) \ 64 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 65 66 /* 67 * Sanitise a uaccess pointer such that it becomes NULL if addr+size 68 * is above the current addr_limit. 69 */ 70 #define uaccess_mask_range_ptr(ptr, size) \ 71 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size)) 72 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, 73 size_t size) 74 { 75 void __user *safe_ptr = (void __user *)ptr; 76 unsigned long tmp; 77 78 asm volatile( 79 " .syntax unified\n" 80 " sub %1, %3, #1\n" 81 " subs %1, %1, %0\n" 82 " addhs %1, %1, #1\n" 83 " subshs %1, %1, %2\n" 84 " movlo %0, #0\n" 85 : "+r" (safe_ptr), "=&r" (tmp) 86 : "r" (size), "r" (TASK_SIZE) 87 : "cc"); 88 89 csdb(); 90 return safe_ptr; 91 } 92 93 /* 94 * Single-value transfer routines. They automatically use the right 95 * size if we just have the right pointer type. Note that the functions 96 * which read from user space (*get_*) need to take care not to leak 97 * kernel data even if the calling code is buggy and fails to check 98 * the return value. This means zeroing out the destination variable 99 * or buffer on error. Normally this is done out of line by the 100 * fixup code, but there are a few places where it intrudes on the 101 * main code path. When we only write to user space, there is no 102 * problem. 103 */ 104 extern int __get_user_1(void *); 105 extern int __get_user_2(void *); 106 extern int __get_user_4(void *); 107 extern int __get_user_32t_8(void *); 108 extern int __get_user_8(void *); 109 extern int __get_user_64t_1(void *); 110 extern int __get_user_64t_2(void *); 111 extern int __get_user_64t_4(void *); 112 113 #define __get_user_x(__r2, __p, __e, __l, __s) \ 114 __asm__ __volatile__ ( \ 115 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 116 __asmeq("%3", "r1") \ 117 "bl __get_user_" #__s \ 118 : "=&r" (__e), "=r" (__r2) \ 119 : "0" (__p), "r" (__l) \ 120 : "ip", "lr", "cc") 121 122 /* narrowing a double-word get into a single 32bit word register: */ 123 #ifdef __ARMEB__ 124 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 125 __get_user_x(__r2, __p, __e, __l, 32t_8) 126 #else 127 #define __get_user_x_32t __get_user_x 128 #endif 129 130 /* 131 * storing result into proper least significant word of 64bit target var, 132 * different only for big endian case where 64 bit __r2 lsw is r3: 133 */ 134 #ifdef __ARMEB__ 135 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 136 __asm__ __volatile__ ( \ 137 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 138 __asmeq("%3", "r1") \ 139 "bl __get_user_64t_" #__s \ 140 : "=&r" (__e), "=r" (__r2) \ 141 : "0" (__p), "r" (__l) \ 142 : "ip", "lr", "cc") 143 #else 144 #define __get_user_x_64t __get_user_x 145 #endif 146 147 148 #define __get_user_check(x, p) \ 149 ({ \ 150 unsigned long __limit = TASK_SIZE - 1; \ 151 register typeof(*(p)) __user *__p asm("r0") = (p); \ 152 register __inttype(x) __r2 asm("r2"); \ 153 register unsigned long __l asm("r1") = __limit; \ 154 register int __e asm("r0"); \ 155 unsigned int __ua_flags = uaccess_save_and_enable(); \ 156 int __tmp_e; \ 157 switch (sizeof(*(__p))) { \ 158 case 1: \ 159 if (sizeof((x)) >= 8) \ 160 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 161 else \ 162 __get_user_x(__r2, __p, __e, __l, 1); \ 163 break; \ 164 case 2: \ 165 if (sizeof((x)) >= 8) \ 166 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 167 else \ 168 __get_user_x(__r2, __p, __e, __l, 2); \ 169 break; \ 170 case 4: \ 171 if (sizeof((x)) >= 8) \ 172 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 173 else \ 174 __get_user_x(__r2, __p, __e, __l, 4); \ 175 break; \ 176 case 8: \ 177 if (sizeof((x)) < 8) \ 178 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 179 else \ 180 __get_user_x(__r2, __p, __e, __l, 8); \ 181 break; \ 182 default: __e = __get_user_bad(); break; \ 183 } \ 184 __tmp_e = __e; \ 185 uaccess_restore(__ua_flags); \ 186 x = (typeof(*(p))) __r2; \ 187 __tmp_e; \ 188 }) 189 190 #define get_user(x, p) \ 191 ({ \ 192 might_fault(); \ 193 __get_user_check(x, p); \ 194 }) 195 196 extern int __put_user_1(void *, unsigned int); 197 extern int __put_user_2(void *, unsigned int); 198 extern int __put_user_4(void *, unsigned int); 199 extern int __put_user_8(void *, unsigned long long); 200 201 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 202 ({ \ 203 unsigned long __limit = TASK_SIZE - 1; \ 204 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 205 register const void __user *__p asm("r0") = __ptr; \ 206 register unsigned long __l asm("r1") = __limit; \ 207 register int __e asm("r0"); \ 208 __asm__ __volatile__ ( \ 209 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 210 __asmeq("%3", "r1") \ 211 "bl __put_user_" #__s \ 212 : "=&r" (__e) \ 213 : "0" (__p), "r" (__r2), "r" (__l) \ 214 : "ip", "lr", "cc"); \ 215 __err = __e; \ 216 }) 217 218 #else /* CONFIG_MMU */ 219 220 #define get_user(x, p) __get_user(x, p) 221 #define __put_user_check __put_user_nocheck 222 223 #endif /* CONFIG_MMU */ 224 225 #include <asm-generic/access_ok.h> 226 227 #ifdef CONFIG_CPU_SPECTRE 228 /* 229 * When mitigating Spectre variant 1, it is not worth fixing the non- 230 * verifying accessors, because we need to add verification of the 231 * address space there. Force these to use the standard get_user() 232 * version instead. 233 */ 234 #define __get_user(x, ptr) get_user(x, ptr) 235 #else 236 237 /* 238 * The "__xxx" versions of the user access functions do not verify the 239 * address space - it must have been done previously with a separate 240 * "access_ok()" call. 241 * 242 * The "xxx_error" versions set the third argument to EFAULT if an 243 * error occurs, and leave it unchanged on success. Note that these 244 * versions are void (ie, don't return a value as such). 245 */ 246 #define __get_user(x, ptr) \ 247 ({ \ 248 long __gu_err = 0; \ 249 __get_user_err((x), (ptr), __gu_err, TUSER()); \ 250 __gu_err; \ 251 }) 252 253 #define __get_user_err(x, ptr, err, __t) \ 254 do { \ 255 unsigned long __gu_addr = (unsigned long)(ptr); \ 256 unsigned long __gu_val; \ 257 unsigned int __ua_flags; \ 258 __chk_user_ptr(ptr); \ 259 might_fault(); \ 260 __ua_flags = uaccess_save_and_enable(); \ 261 switch (sizeof(*(ptr))) { \ 262 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \ 263 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \ 264 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \ 265 default: (__gu_val) = __get_user_bad(); \ 266 } \ 267 uaccess_restore(__ua_flags); \ 268 (x) = (__typeof__(*(ptr)))__gu_val; \ 269 } while (0) 270 #endif 271 272 #define __get_user_asm(x, addr, err, instr) \ 273 __asm__ __volatile__( \ 274 "1: " instr " %1, [%2], #0\n" \ 275 "2:\n" \ 276 " .pushsection .text.fixup,\"ax\"\n" \ 277 " .align 2\n" \ 278 "3: mov %0, %3\n" \ 279 " mov %1, #0\n" \ 280 " b 2b\n" \ 281 " .popsection\n" \ 282 " .pushsection __ex_table,\"a\"\n" \ 283 " .align 3\n" \ 284 " .long 1b, 3b\n" \ 285 " .popsection" \ 286 : "+r" (err), "=&r" (x) \ 287 : "r" (addr), "i" (-EFAULT) \ 288 : "cc") 289 290 #define __get_user_asm_byte(x, addr, err, __t) \ 291 __get_user_asm(x, addr, err, "ldrb" __t) 292 293 #if __LINUX_ARM_ARCH__ >= 6 294 295 #define __get_user_asm_half(x, addr, err, __t) \ 296 __get_user_asm(x, addr, err, "ldrh" __t) 297 298 #else 299 300 #ifndef __ARMEB__ 301 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 302 ({ \ 303 unsigned long __b1, __b2; \ 304 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 305 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 306 (x) = __b1 | (__b2 << 8); \ 307 }) 308 #else 309 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 310 ({ \ 311 unsigned long __b1, __b2; \ 312 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 313 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 314 (x) = (__b1 << 8) | __b2; \ 315 }) 316 #endif 317 318 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 319 320 #define __get_user_asm_word(x, addr, err, __t) \ 321 __get_user_asm(x, addr, err, "ldr" __t) 322 323 #define __put_user_switch(x, ptr, __err, __fn) \ 324 do { \ 325 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 326 __typeof__(*(ptr)) __pu_val = (x); \ 327 unsigned int __ua_flags; \ 328 might_fault(); \ 329 __ua_flags = uaccess_save_and_enable(); \ 330 switch (sizeof(*(ptr))) { \ 331 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 332 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 333 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 334 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 335 default: __err = __put_user_bad(); break; \ 336 } \ 337 uaccess_restore(__ua_flags); \ 338 } while (0) 339 340 #define put_user(x, ptr) \ 341 ({ \ 342 int __pu_err = 0; \ 343 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 344 __pu_err; \ 345 }) 346 347 #ifdef CONFIG_CPU_SPECTRE 348 /* 349 * When mitigating Spectre variant 1.1, all accessors need to include 350 * verification of the address space. 351 */ 352 #define __put_user(x, ptr) put_user(x, ptr) 353 354 #else 355 #define __put_user(x, ptr) \ 356 ({ \ 357 long __pu_err = 0; \ 358 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 359 __pu_err; \ 360 }) 361 362 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 363 do { \ 364 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 365 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\ 366 } while (0) 367 368 #define __put_user_nocheck_1 __put_user_asm_byte 369 #define __put_user_nocheck_2 __put_user_asm_half 370 #define __put_user_nocheck_4 __put_user_asm_word 371 #define __put_user_nocheck_8 __put_user_asm_dword 372 373 #endif /* !CONFIG_CPU_SPECTRE */ 374 375 #define __put_user_asm(x, __pu_addr, err, instr) \ 376 __asm__ __volatile__( \ 377 "1: " instr " %1, [%2], #0\n" \ 378 "2:\n" \ 379 " .pushsection .text.fixup,\"ax\"\n" \ 380 " .align 2\n" \ 381 "3: mov %0, %3\n" \ 382 " b 2b\n" \ 383 " .popsection\n" \ 384 " .pushsection __ex_table,\"a\"\n" \ 385 " .align 3\n" \ 386 " .long 1b, 3b\n" \ 387 " .popsection" \ 388 : "+r" (err) \ 389 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 390 : "cc") 391 392 #define __put_user_asm_byte(x, __pu_addr, err, __t) \ 393 __put_user_asm(x, __pu_addr, err, "strb" __t) 394 395 #if __LINUX_ARM_ARCH__ >= 6 396 397 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 398 __put_user_asm(x, __pu_addr, err, "strh" __t) 399 400 #else 401 402 #ifndef __ARMEB__ 403 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 404 ({ \ 405 unsigned long __temp = (__force unsigned long)(x); \ 406 __put_user_asm_byte(__temp, __pu_addr, err, __t); \ 407 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\ 408 }) 409 #else 410 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 411 ({ \ 412 unsigned long __temp = (__force unsigned long)(x); \ 413 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \ 414 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \ 415 }) 416 #endif 417 418 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 419 420 #define __put_user_asm_word(x, __pu_addr, err, __t) \ 421 __put_user_asm(x, __pu_addr, err, "str" __t) 422 423 #ifndef __ARMEB__ 424 #define __reg_oper0 "%R2" 425 #define __reg_oper1 "%Q2" 426 #else 427 #define __reg_oper0 "%Q2" 428 #define __reg_oper1 "%R2" 429 #endif 430 431 #define __put_user_asm_dword(x, __pu_addr, err, __t) \ 432 __asm__ __volatile__( \ 433 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \ 434 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \ 435 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \ 436 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \ 437 "3:\n" \ 438 " .pushsection .text.fixup,\"ax\"\n" \ 439 " .align 2\n" \ 440 "4: mov %0, %3\n" \ 441 " b 3b\n" \ 442 " .popsection\n" \ 443 " .pushsection __ex_table,\"a\"\n" \ 444 " .align 3\n" \ 445 " .long 1b, 4b\n" \ 446 " .long 2b, 4b\n" \ 447 " .popsection" \ 448 : "+r" (err), "+r" (__pu_addr) \ 449 : "r" (x), "i" (-EFAULT) \ 450 : "cc") 451 452 #define __get_kernel_nofault(dst, src, type, err_label) \ 453 do { \ 454 const type *__pk_ptr = (src); \ 455 unsigned long __src = (unsigned long)(__pk_ptr); \ 456 type __val; \ 457 int __err = 0; \ 458 switch (sizeof(type)) { \ 459 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \ 460 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \ 461 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \ 462 case 8: { \ 463 u32 *__v32 = (u32*)&__val; \ 464 __get_user_asm_word(__v32[0], __src, __err, ""); \ 465 if (__err) \ 466 break; \ 467 __get_user_asm_word(__v32[1], __src+4, __err, ""); \ 468 break; \ 469 } \ 470 default: __err = __get_user_bad(); break; \ 471 } \ 472 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) \ 473 put_unaligned(__val, (type *)(dst)); \ 474 else \ 475 *(type *)(dst) = __val; /* aligned by caller */ \ 476 if (__err) \ 477 goto err_label; \ 478 } while (0) 479 480 #define __put_kernel_nofault(dst, src, type, err_label) \ 481 do { \ 482 const type *__pk_ptr = (dst); \ 483 unsigned long __dst = (unsigned long)__pk_ptr; \ 484 int __err = 0; \ 485 type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \ 486 ? get_unaligned((type *)(src)) \ 487 : *(type *)(src); /* aligned by caller */ \ 488 switch (sizeof(type)) { \ 489 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \ 490 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \ 491 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \ 492 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \ 493 default: __err = __put_user_bad(); break; \ 494 } \ 495 if (__err) \ 496 goto err_label; \ 497 } while (0) 498 499 #ifdef CONFIG_MMU 500 extern unsigned long __must_check 501 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 502 503 static inline unsigned long __must_check 504 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 505 { 506 unsigned int __ua_flags; 507 508 __ua_flags = uaccess_save_and_enable(); 509 n = arm_copy_from_user(to, from, n); 510 uaccess_restore(__ua_flags); 511 return n; 512 } 513 514 extern unsigned long __must_check 515 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 516 extern unsigned long __must_check 517 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 518 519 static inline unsigned long __must_check 520 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 521 { 522 #ifndef CONFIG_UACCESS_WITH_MEMCPY 523 unsigned int __ua_flags; 524 __ua_flags = uaccess_save_and_enable(); 525 n = arm_copy_to_user(to, from, n); 526 uaccess_restore(__ua_flags); 527 return n; 528 #else 529 return arm_copy_to_user(to, from, n); 530 #endif 531 } 532 533 extern unsigned long __must_check 534 arm_clear_user(void __user *addr, unsigned long n); 535 extern unsigned long __must_check 536 __clear_user_std(void __user *addr, unsigned long n); 537 538 static inline unsigned long __must_check 539 __clear_user(void __user *addr, unsigned long n) 540 { 541 unsigned int __ua_flags = uaccess_save_and_enable(); 542 n = arm_clear_user(addr, n); 543 uaccess_restore(__ua_flags); 544 return n; 545 } 546 547 #else 548 static inline unsigned long 549 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 550 { 551 memcpy(to, (const void __force *)from, n); 552 return 0; 553 } 554 static inline unsigned long 555 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 556 { 557 memcpy((void __force *)to, from, n); 558 return 0; 559 } 560 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 561 #endif 562 #define INLINE_COPY_TO_USER 563 #define INLINE_COPY_FROM_USER 564 565 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 566 { 567 if (access_ok(to, n)) 568 n = __clear_user(to, n); 569 return n; 570 } 571 572 /* These are from lib/ code, and use __get_user() and friends */ 573 extern long strncpy_from_user(char *dest, const char __user *src, long count); 574 575 extern __must_check long strnlen_user(const char __user *str, long n); 576 577 #endif /* _ASMARM_UACCESS_H */ 578