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 __get_user_x(__r2, __p, __e, __l, __s) \ 113 __asm__ __volatile__ ( \ 114 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 115 __asmeq("%3", "r1") \ 116 "bl __get_user_" #__s \ 117 : "=&r" (__e), "=r" (__r2) \ 118 : "0" (__p), "r" (__l) \ 119 : "ip", "lr", "cc") 120 121 /* narrowing a double-word get into a single 32bit word register: */ 122 #ifdef __ARMEB__ 123 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 124 __get_user_x(__r2, __p, __e, __l, 32t_8) 125 #else 126 #define __get_user_x_32t __get_user_x 127 #endif 128 129 /* 130 * storing result into proper least significant word of 64bit target var, 131 * different only for big endian case where 64 bit __r2 lsw is r3: 132 */ 133 #ifdef __ARMEB__ 134 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 135 __asm__ __volatile__ ( \ 136 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 137 __asmeq("%3", "r1") \ 138 "bl __get_user_64t_" #__s \ 139 : "=&r" (__e), "=r" (__r2) \ 140 : "0" (__p), "r" (__l) \ 141 : "ip", "lr", "cc") 142 #else 143 #define __get_user_x_64t __get_user_x 144 #endif 145 146 147 #define __get_user_check(x, p) \ 148 ({ \ 149 unsigned long __limit = TASK_SIZE - 1; \ 150 register typeof(*(p)) __user *__p asm("r0") = (p); \ 151 register __inttype(x) __r2 asm("r2"); \ 152 register unsigned long __l asm("r1") = __limit; \ 153 register int __e asm("r0"); \ 154 unsigned int __ua_flags = uaccess_save_and_enable(); \ 155 int __tmp_e; \ 156 switch (sizeof(*(__p))) { \ 157 case 1: \ 158 if (sizeof((x)) >= 8) \ 159 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 160 else \ 161 __get_user_x(__r2, __p, __e, __l, 1); \ 162 break; \ 163 case 2: \ 164 if (sizeof((x)) >= 8) \ 165 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 166 else \ 167 __get_user_x(__r2, __p, __e, __l, 2); \ 168 break; \ 169 case 4: \ 170 if (sizeof((x)) >= 8) \ 171 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 172 else \ 173 __get_user_x(__r2, __p, __e, __l, 4); \ 174 break; \ 175 case 8: \ 176 if (sizeof((x)) < 8) \ 177 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 178 else \ 179 __get_user_x(__r2, __p, __e, __l, 8); \ 180 break; \ 181 default: __e = __get_user_bad(); break; \ 182 } \ 183 __tmp_e = __e; \ 184 uaccess_restore(__ua_flags); \ 185 x = (typeof(*(p))) __r2; \ 186 __tmp_e; \ 187 }) 188 189 #define get_user(x, p) \ 190 ({ \ 191 might_fault(); \ 192 __get_user_check(x, p); \ 193 }) 194 195 extern int __put_user_1(void *, unsigned int); 196 extern int __put_user_2(void *, unsigned int); 197 extern int __put_user_4(void *, unsigned int); 198 extern int __put_user_8(void *, unsigned long long); 199 200 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 201 ({ \ 202 unsigned long __limit = TASK_SIZE - 1; \ 203 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 204 register const void __user *__p asm("r0") = __ptr; \ 205 register unsigned long __l asm("r1") = __limit; \ 206 register int __e asm("r0"); \ 207 __asm__ __volatile__ ( \ 208 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 209 __asmeq("%3", "r1") \ 210 "bl __put_user_" #__s \ 211 : "=&r" (__e) \ 212 : "0" (__p), "r" (__r2), "r" (__l) \ 213 : "ip", "lr", "cc"); \ 214 __err = __e; \ 215 }) 216 217 #else /* CONFIG_MMU */ 218 219 #define get_user(x, p) __get_user(x, p) 220 #define __put_user_check __put_user_nocheck 221 222 #endif /* CONFIG_MMU */ 223 224 #include <asm-generic/access_ok.h> 225 226 #ifdef CONFIG_CPU_SPECTRE 227 /* 228 * When mitigating Spectre variant 1, it is not worth fixing the non- 229 * verifying accessors, because we need to add verification of the 230 * address space there. Force these to use the standard get_user() 231 * version instead. 232 */ 233 #define __get_user(x, ptr) get_user(x, ptr) 234 #else 235 236 /* 237 * The "__xxx" versions of the user access functions do not verify the 238 * address space - it must have been done previously with a separate 239 * "access_ok()" call. 240 * 241 * The "xxx_error" versions set the third argument to EFAULT if an 242 * error occurs, and leave it unchanged on success. Note that these 243 * versions are void (ie, don't return a value as such). 244 */ 245 #define __get_user(x, ptr) \ 246 ({ \ 247 long __gu_err = 0; \ 248 __get_user_err((x), (ptr), __gu_err, TUSER()); \ 249 __gu_err; \ 250 }) 251 252 #define __get_user_err(x, ptr, err, __t) \ 253 do { \ 254 unsigned long __gu_addr = (unsigned long)(ptr); \ 255 unsigned long __gu_val; \ 256 unsigned int __ua_flags; \ 257 __chk_user_ptr(ptr); \ 258 might_fault(); \ 259 __ua_flags = uaccess_save_and_enable(); \ 260 switch (sizeof(*(ptr))) { \ 261 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err, __t); break; \ 262 case 2: __get_user_asm_half(__gu_val, __gu_addr, err, __t); break; \ 263 case 4: __get_user_asm_word(__gu_val, __gu_addr, err, __t); break; \ 264 default: (__gu_val) = __get_user_bad(); \ 265 } \ 266 uaccess_restore(__ua_flags); \ 267 (x) = (__typeof__(*(ptr)))__gu_val; \ 268 } while (0) 269 #endif 270 271 #define __get_user_asm(x, addr, err, instr) \ 272 __asm__ __volatile__( \ 273 "1: " instr " %1, [%2], #0\n" \ 274 "2:\n" \ 275 " .pushsection .text.fixup,\"ax\"\n" \ 276 " .align 2\n" \ 277 "3: mov %0, %3\n" \ 278 " mov %1, #0\n" \ 279 " b 2b\n" \ 280 " .popsection\n" \ 281 " .pushsection __ex_table,\"a\"\n" \ 282 " .align 3\n" \ 283 " .long 1b, 3b\n" \ 284 " .popsection" \ 285 : "+r" (err), "=&r" (x) \ 286 : "r" (addr), "i" (-EFAULT) \ 287 : "cc") 288 289 #define __get_user_asm_byte(x, addr, err, __t) \ 290 __get_user_asm(x, addr, err, "ldrb" __t) 291 292 #if __LINUX_ARM_ARCH__ >= 6 293 294 #define __get_user_asm_half(x, addr, err, __t) \ 295 __get_user_asm(x, addr, err, "ldrh" __t) 296 297 #else 298 299 #ifndef __ARMEB__ 300 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 301 ({ \ 302 unsigned long __b1, __b2; \ 303 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 304 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 305 (x) = __b1 | (__b2 << 8); \ 306 }) 307 #else 308 #define __get_user_asm_half(x, __gu_addr, err, __t) \ 309 ({ \ 310 unsigned long __b1, __b2; \ 311 __get_user_asm_byte(__b1, __gu_addr, err, __t); \ 312 __get_user_asm_byte(__b2, __gu_addr + 1, err, __t); \ 313 (x) = (__b1 << 8) | __b2; \ 314 }) 315 #endif 316 317 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 318 319 #define __get_user_asm_word(x, addr, err, __t) \ 320 __get_user_asm(x, addr, err, "ldr" __t) 321 322 #define __put_user_switch(x, ptr, __err, __fn) \ 323 do { \ 324 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 325 __typeof__(*(ptr)) __pu_val = (x); \ 326 unsigned int __ua_flags; \ 327 might_fault(); \ 328 __ua_flags = uaccess_save_and_enable(); \ 329 switch (sizeof(*(ptr))) { \ 330 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 331 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 332 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 333 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 334 default: __err = __put_user_bad(); break; \ 335 } \ 336 uaccess_restore(__ua_flags); \ 337 } while (0) 338 339 #define put_user(x, ptr) \ 340 ({ \ 341 int __pu_err = 0; \ 342 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 343 __pu_err; \ 344 }) 345 346 #ifdef CONFIG_CPU_SPECTRE 347 /* 348 * When mitigating Spectre variant 1.1, all accessors need to include 349 * verification of the address space. 350 */ 351 #define __put_user(x, ptr) put_user(x, ptr) 352 353 #else 354 #define __put_user(x, ptr) \ 355 ({ \ 356 long __pu_err = 0; \ 357 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 358 __pu_err; \ 359 }) 360 361 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 362 do { \ 363 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 364 __put_user_nocheck_##__size(x, __pu_addr, __err, TUSER());\ 365 } while (0) 366 367 #define __put_user_nocheck_1 __put_user_asm_byte 368 #define __put_user_nocheck_2 __put_user_asm_half 369 #define __put_user_nocheck_4 __put_user_asm_word 370 #define __put_user_nocheck_8 __put_user_asm_dword 371 372 #endif /* !CONFIG_CPU_SPECTRE */ 373 374 #define __put_user_asm(x, __pu_addr, err, instr) \ 375 __asm__ __volatile__( \ 376 "1: " instr " %1, [%2], #0\n" \ 377 "2:\n" \ 378 " .pushsection .text.fixup,\"ax\"\n" \ 379 " .align 2\n" \ 380 "3: mov %0, %3\n" \ 381 " b 2b\n" \ 382 " .popsection\n" \ 383 " .pushsection __ex_table,\"a\"\n" \ 384 " .align 3\n" \ 385 " .long 1b, 3b\n" \ 386 " .popsection" \ 387 : "+r" (err) \ 388 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 389 : "cc") 390 391 #define __put_user_asm_byte(x, __pu_addr, err, __t) \ 392 __put_user_asm(x, __pu_addr, err, "strb" __t) 393 394 #if __LINUX_ARM_ARCH__ >= 6 395 396 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 397 __put_user_asm(x, __pu_addr, err, "strh" __t) 398 399 #else 400 401 #ifndef __ARMEB__ 402 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 403 ({ \ 404 unsigned long __temp = (__force unsigned long)(x); \ 405 __put_user_asm_byte(__temp, __pu_addr, err, __t); \ 406 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err, __t);\ 407 }) 408 #else 409 #define __put_user_asm_half(x, __pu_addr, err, __t) \ 410 ({ \ 411 unsigned long __temp = (__force unsigned long)(x); \ 412 __put_user_asm_byte(__temp >> 8, __pu_addr, err, __t); \ 413 __put_user_asm_byte(__temp, __pu_addr + 1, err, __t); \ 414 }) 415 #endif 416 417 #endif /* __LINUX_ARM_ARCH__ >= 6 */ 418 419 #define __put_user_asm_word(x, __pu_addr, err, __t) \ 420 __put_user_asm(x, __pu_addr, err, "str" __t) 421 422 #ifndef __ARMEB__ 423 #define __reg_oper0 "%R2" 424 #define __reg_oper1 "%Q2" 425 #else 426 #define __reg_oper0 "%Q2" 427 #define __reg_oper1 "%R2" 428 #endif 429 430 #define __put_user_asm_dword(x, __pu_addr, err, __t) \ 431 __asm__ __volatile__( \ 432 ARM( "1: str" __t " " __reg_oper1 ", [%1], #4\n" ) \ 433 ARM( "2: str" __t " " __reg_oper0 ", [%1]\n" ) \ 434 THUMB( "1: str" __t " " __reg_oper1 ", [%1]\n" ) \ 435 THUMB( "2: str" __t " " __reg_oper0 ", [%1, #4]\n" ) \ 436 "3:\n" \ 437 " .pushsection .text.fixup,\"ax\"\n" \ 438 " .align 2\n" \ 439 "4: mov %0, %3\n" \ 440 " b 3b\n" \ 441 " .popsection\n" \ 442 " .pushsection __ex_table,\"a\"\n" \ 443 " .align 3\n" \ 444 " .long 1b, 4b\n" \ 445 " .long 2b, 4b\n" \ 446 " .popsection" \ 447 : "+r" (err), "+r" (__pu_addr) \ 448 : "r" (x), "i" (-EFAULT) \ 449 : "cc") 450 451 #define __get_kernel_nofault(dst, src, type, err_label) \ 452 do { \ 453 const type *__pk_ptr = (src); \ 454 unsigned long __src = (unsigned long)(__pk_ptr); \ 455 type __val; \ 456 int __err = 0; \ 457 switch (sizeof(type)) { \ 458 case 1: __get_user_asm_byte(__val, __src, __err, ""); break; \ 459 case 2: __get_user_asm_half(__val, __src, __err, ""); break; \ 460 case 4: __get_user_asm_word(__val, __src, __err, ""); break; \ 461 case 8: { \ 462 u32 *__v32 = (u32*)&__val; \ 463 __get_user_asm_word(__v32[0], __src, __err, ""); \ 464 if (__err) \ 465 break; \ 466 __get_user_asm_word(__v32[1], __src+4, __err, ""); \ 467 break; \ 468 } \ 469 default: __err = __get_user_bad(); break; \ 470 } \ 471 if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) \ 472 put_unaligned(__val, (type *)(dst)); \ 473 else \ 474 *(type *)(dst) = __val; /* aligned by caller */ \ 475 if (__err) \ 476 goto err_label; \ 477 } while (0) 478 479 #define __put_kernel_nofault(dst, src, type, err_label) \ 480 do { \ 481 const type *__pk_ptr = (dst); \ 482 unsigned long __dst = (unsigned long)__pk_ptr; \ 483 int __err = 0; \ 484 type __val = IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) \ 485 ? get_unaligned((type *)(src)) \ 486 : *(type *)(src); /* aligned by caller */ \ 487 switch (sizeof(type)) { \ 488 case 1: __put_user_asm_byte(__val, __dst, __err, ""); break; \ 489 case 2: __put_user_asm_half(__val, __dst, __err, ""); break; \ 490 case 4: __put_user_asm_word(__val, __dst, __err, ""); break; \ 491 case 8: __put_user_asm_dword(__val, __dst, __err, ""); break; \ 492 default: __err = __put_user_bad(); break; \ 493 } \ 494 if (__err) \ 495 goto err_label; \ 496 } while (0) 497 498 #ifdef CONFIG_MMU 499 extern unsigned long __must_check 500 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 501 502 static inline unsigned long __must_check 503 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 504 { 505 unsigned int __ua_flags; 506 507 __ua_flags = uaccess_save_and_enable(); 508 n = arm_copy_from_user(to, from, n); 509 uaccess_restore(__ua_flags); 510 return n; 511 } 512 513 extern unsigned long __must_check 514 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 515 extern unsigned long __must_check 516 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 517 518 static inline unsigned long __must_check 519 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 520 { 521 #ifndef CONFIG_UACCESS_WITH_MEMCPY 522 unsigned int __ua_flags; 523 __ua_flags = uaccess_save_and_enable(); 524 n = arm_copy_to_user(to, from, n); 525 uaccess_restore(__ua_flags); 526 return n; 527 #else 528 return arm_copy_to_user(to, from, n); 529 #endif 530 } 531 532 extern unsigned long __must_check 533 arm_clear_user(void __user *addr, unsigned long n); 534 extern unsigned long __must_check 535 __clear_user_std(void __user *addr, unsigned long n); 536 537 static inline unsigned long __must_check 538 __clear_user(void __user *addr, unsigned long n) 539 { 540 unsigned int __ua_flags = uaccess_save_and_enable(); 541 n = arm_clear_user(addr, n); 542 uaccess_restore(__ua_flags); 543 return n; 544 } 545 546 #else 547 static inline unsigned long 548 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 549 { 550 memcpy(to, (const void __force *)from, n); 551 return 0; 552 } 553 static inline unsigned long 554 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 555 { 556 memcpy((void __force *)to, from, n); 557 return 0; 558 } 559 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 560 #endif 561 #define INLINE_COPY_TO_USER 562 #define INLINE_COPY_FROM_USER 563 564 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 565 { 566 if (access_ok(to, n)) 567 n = __clear_user(to, n); 568 return n; 569 } 570 571 /* These are from lib/ code, and use __get_user() and friends */ 572 extern long strncpy_from_user(char *dest, const char __user *src, long count); 573 574 extern __must_check long strnlen_user(const char __user *str, long n); 575 576 #endif /* _ASMARM_UACCESS_H */ 577