1 /* 2 * arch/arm/include/asm/uaccess.h 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 */ 8 #ifndef _ASMARM_UACCESS_H 9 #define _ASMARM_UACCESS_H 10 11 /* 12 * User space memory access functions 13 */ 14 #include <linux/string.h> 15 #include <asm/memory.h> 16 #include <asm/domain.h> 17 #include <asm/unified.h> 18 #include <asm/compiler.h> 19 20 #include <asm/extable.h> 21 22 /* 23 * These two functions allow hooking accesses to userspace to increase 24 * system integrity by ensuring that the kernel can not inadvertantly 25 * perform such accesses (eg, via list poison values) which could then 26 * be exploited for priviledge escalation. 27 */ 28 static inline unsigned int uaccess_save_and_enable(void) 29 { 30 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 31 unsigned int old_domain = get_domain(); 32 33 /* Set the current domain access to permit user accesses */ 34 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) | 35 domain_val(DOMAIN_USER, DOMAIN_CLIENT)); 36 37 return old_domain; 38 #else 39 return 0; 40 #endif 41 } 42 43 static inline void uaccess_restore(unsigned int flags) 44 { 45 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 46 /* Restore the user access mask */ 47 set_domain(flags); 48 #endif 49 } 50 51 /* 52 * These two are intentionally not defined anywhere - if the kernel 53 * code generates any references to them, that's a bug. 54 */ 55 extern int __get_user_bad(void); 56 extern int __put_user_bad(void); 57 58 /* 59 * Note that this is actually 0x1,0000,0000 60 */ 61 #define KERNEL_DS 0x00000000 62 #define get_ds() (KERNEL_DS) 63 64 #ifdef CONFIG_MMU 65 66 #define USER_DS TASK_SIZE 67 #define get_fs() (current_thread_info()->addr_limit) 68 69 static inline void set_fs(mm_segment_t fs) 70 { 71 current_thread_info()->addr_limit = fs; 72 73 /* 74 * Prevent a mispredicted conditional call to set_fs from forwarding 75 * the wrong address limit to access_ok under speculation. 76 */ 77 dsb(nsh); 78 isb(); 79 80 modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); 81 } 82 83 #define segment_eq(a, b) ((a) == (b)) 84 85 /* We use 33-bit arithmetic here... */ 86 #define __range_ok(addr, size) ({ \ 87 unsigned long flag, roksum; \ 88 __chk_user_ptr(addr); \ 89 __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \ 90 : "=&r" (flag), "=&r" (roksum) \ 91 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ 92 : "cc"); \ 93 flag; }) 94 95 /* 96 * This is a type: either unsigned long, if the argument fits into 97 * that type, or otherwise unsigned long long. 98 */ 99 #define __inttype(x) \ 100 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 101 102 /* 103 * Sanitise a uaccess pointer such that it becomes NULL if addr+size 104 * is above the current addr_limit. 105 */ 106 #define uaccess_mask_range_ptr(ptr, size) \ 107 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size)) 108 static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, 109 size_t size) 110 { 111 void __user *safe_ptr = (void __user *)ptr; 112 unsigned long tmp; 113 114 asm volatile( 115 " sub %1, %3, #1\n" 116 " subs %1, %1, %0\n" 117 " addhs %1, %1, #1\n" 118 " subhss %1, %1, %2\n" 119 " movlo %0, #0\n" 120 : "+r" (safe_ptr), "=&r" (tmp) 121 : "r" (size), "r" (current_thread_info()->addr_limit) 122 : "cc"); 123 124 csdb(); 125 return safe_ptr; 126 } 127 128 /* 129 * Single-value transfer routines. They automatically use the right 130 * size if we just have the right pointer type. Note that the functions 131 * which read from user space (*get_*) need to take care not to leak 132 * kernel data even if the calling code is buggy and fails to check 133 * the return value. This means zeroing out the destination variable 134 * or buffer on error. Normally this is done out of line by the 135 * fixup code, but there are a few places where it intrudes on the 136 * main code path. When we only write to user space, there is no 137 * problem. 138 */ 139 extern int __get_user_1(void *); 140 extern int __get_user_2(void *); 141 extern int __get_user_4(void *); 142 extern int __get_user_32t_8(void *); 143 extern int __get_user_8(void *); 144 extern int __get_user_64t_1(void *); 145 extern int __get_user_64t_2(void *); 146 extern int __get_user_64t_4(void *); 147 148 #define __GUP_CLOBBER_1 "lr", "cc" 149 #ifdef CONFIG_CPU_USE_DOMAINS 150 #define __GUP_CLOBBER_2 "ip", "lr", "cc" 151 #else 152 #define __GUP_CLOBBER_2 "lr", "cc" 153 #endif 154 #define __GUP_CLOBBER_4 "lr", "cc" 155 #define __GUP_CLOBBER_32t_8 "lr", "cc" 156 #define __GUP_CLOBBER_8 "lr", "cc" 157 158 #define __get_user_x(__r2, __p, __e, __l, __s) \ 159 __asm__ __volatile__ ( \ 160 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 161 __asmeq("%3", "r1") \ 162 "bl __get_user_" #__s \ 163 : "=&r" (__e), "=r" (__r2) \ 164 : "0" (__p), "r" (__l) \ 165 : __GUP_CLOBBER_##__s) 166 167 /* narrowing a double-word get into a single 32bit word register: */ 168 #ifdef __ARMEB__ 169 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 170 __get_user_x(__r2, __p, __e, __l, 32t_8) 171 #else 172 #define __get_user_x_32t __get_user_x 173 #endif 174 175 /* 176 * storing result into proper least significant word of 64bit target var, 177 * different only for big endian case where 64 bit __r2 lsw is r3: 178 */ 179 #ifdef __ARMEB__ 180 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 181 __asm__ __volatile__ ( \ 182 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 183 __asmeq("%3", "r1") \ 184 "bl __get_user_64t_" #__s \ 185 : "=&r" (__e), "=r" (__r2) \ 186 : "0" (__p), "r" (__l) \ 187 : __GUP_CLOBBER_##__s) 188 #else 189 #define __get_user_x_64t __get_user_x 190 #endif 191 192 193 #define __get_user_check(x, p) \ 194 ({ \ 195 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 196 register typeof(*(p)) __user *__p asm("r0") = (p); \ 197 register __inttype(x) __r2 asm("r2"); \ 198 register unsigned long __l asm("r1") = __limit; \ 199 register int __e asm("r0"); \ 200 unsigned int __ua_flags = uaccess_save_and_enable(); \ 201 switch (sizeof(*(__p))) { \ 202 case 1: \ 203 if (sizeof((x)) >= 8) \ 204 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 205 else \ 206 __get_user_x(__r2, __p, __e, __l, 1); \ 207 break; \ 208 case 2: \ 209 if (sizeof((x)) >= 8) \ 210 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 211 else \ 212 __get_user_x(__r2, __p, __e, __l, 2); \ 213 break; \ 214 case 4: \ 215 if (sizeof((x)) >= 8) \ 216 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 217 else \ 218 __get_user_x(__r2, __p, __e, __l, 4); \ 219 break; \ 220 case 8: \ 221 if (sizeof((x)) < 8) \ 222 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 223 else \ 224 __get_user_x(__r2, __p, __e, __l, 8); \ 225 break; \ 226 default: __e = __get_user_bad(); break; \ 227 } \ 228 uaccess_restore(__ua_flags); \ 229 x = (typeof(*(p))) __r2; \ 230 __e; \ 231 }) 232 233 #define get_user(x, p) \ 234 ({ \ 235 might_fault(); \ 236 __get_user_check(x, p); \ 237 }) 238 239 extern int __put_user_1(void *, unsigned int); 240 extern int __put_user_2(void *, unsigned int); 241 extern int __put_user_4(void *, unsigned int); 242 extern int __put_user_8(void *, unsigned long long); 243 244 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 245 ({ \ 246 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 247 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 248 register const void __user *__p asm("r0") = __ptr; \ 249 register unsigned long __l asm("r1") = __limit; \ 250 register int __e asm("r0"); \ 251 __asm__ __volatile__ ( \ 252 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 253 __asmeq("%3", "r1") \ 254 "bl __put_user_" #__s \ 255 : "=&r" (__e) \ 256 : "0" (__p), "r" (__r2), "r" (__l) \ 257 : "ip", "lr", "cc"); \ 258 __err = __e; \ 259 }) 260 261 #else /* CONFIG_MMU */ 262 263 /* 264 * uClinux has only one addr space, so has simplified address limits. 265 */ 266 #define USER_DS KERNEL_DS 267 268 #define segment_eq(a, b) (1) 269 #define __addr_ok(addr) ((void)(addr), 1) 270 #define __range_ok(addr, size) ((void)(addr), 0) 271 #define get_fs() (KERNEL_DS) 272 273 static inline void set_fs(mm_segment_t fs) 274 { 275 } 276 277 #define get_user(x, p) __get_user(x, p) 278 #define __put_user_check __put_user_nocheck 279 280 #endif /* CONFIG_MMU */ 281 282 #define access_ok(type, addr, size) (__range_ok(addr, size) == 0) 283 284 #define user_addr_max() \ 285 (uaccess_kernel() ? ~0UL : get_fs()) 286 287 #ifdef CONFIG_CPU_SPECTRE 288 /* 289 * When mitigating Spectre variant 1, it is not worth fixing the non- 290 * verifying accessors, because we need to add verification of the 291 * address space there. Force these to use the standard get_user() 292 * version instead. 293 */ 294 #define __get_user(x, ptr) get_user(x, ptr) 295 #else 296 297 /* 298 * The "__xxx" versions of the user access functions do not verify the 299 * address space - it must have been done previously with a separate 300 * "access_ok()" call. 301 * 302 * The "xxx_error" versions set the third argument to EFAULT if an 303 * error occurs, and leave it unchanged on success. Note that these 304 * versions are void (ie, don't return a value as such). 305 */ 306 #define __get_user(x, ptr) \ 307 ({ \ 308 long __gu_err = 0; \ 309 __get_user_err((x), (ptr), __gu_err); \ 310 __gu_err; \ 311 }) 312 313 #define __get_user_err(x, ptr, err) \ 314 do { \ 315 unsigned long __gu_addr = (unsigned long)(ptr); \ 316 unsigned long __gu_val; \ 317 unsigned int __ua_flags; \ 318 __chk_user_ptr(ptr); \ 319 might_fault(); \ 320 __ua_flags = uaccess_save_and_enable(); \ 321 switch (sizeof(*(ptr))) { \ 322 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \ 323 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \ 324 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \ 325 default: (__gu_val) = __get_user_bad(); \ 326 } \ 327 uaccess_restore(__ua_flags); \ 328 (x) = (__typeof__(*(ptr)))__gu_val; \ 329 } while (0) 330 331 #define __get_user_asm(x, addr, err, instr) \ 332 __asm__ __volatile__( \ 333 "1: " TUSER(instr) " %1, [%2], #0\n" \ 334 "2:\n" \ 335 " .pushsection .text.fixup,\"ax\"\n" \ 336 " .align 2\n" \ 337 "3: mov %0, %3\n" \ 338 " mov %1, #0\n" \ 339 " b 2b\n" \ 340 " .popsection\n" \ 341 " .pushsection __ex_table,\"a\"\n" \ 342 " .align 3\n" \ 343 " .long 1b, 3b\n" \ 344 " .popsection" \ 345 : "+r" (err), "=&r" (x) \ 346 : "r" (addr), "i" (-EFAULT) \ 347 : "cc") 348 349 #define __get_user_asm_byte(x, addr, err) \ 350 __get_user_asm(x, addr, err, ldrb) 351 352 #ifndef __ARMEB__ 353 #define __get_user_asm_half(x, __gu_addr, err) \ 354 ({ \ 355 unsigned long __b1, __b2; \ 356 __get_user_asm_byte(__b1, __gu_addr, err); \ 357 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 358 (x) = __b1 | (__b2 << 8); \ 359 }) 360 #else 361 #define __get_user_asm_half(x, __gu_addr, err) \ 362 ({ \ 363 unsigned long __b1, __b2; \ 364 __get_user_asm_byte(__b1, __gu_addr, err); \ 365 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 366 (x) = (__b1 << 8) | __b2; \ 367 }) 368 #endif 369 370 #define __get_user_asm_word(x, addr, err) \ 371 __get_user_asm(x, addr, err, ldr) 372 #endif 373 374 375 #define __put_user_switch(x, ptr, __err, __fn) \ 376 do { \ 377 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 378 __typeof__(*(ptr)) __pu_val = (x); \ 379 unsigned int __ua_flags; \ 380 might_fault(); \ 381 __ua_flags = uaccess_save_and_enable(); \ 382 switch (sizeof(*(ptr))) { \ 383 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 384 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 385 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 386 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 387 default: __err = __put_user_bad(); break; \ 388 } \ 389 uaccess_restore(__ua_flags); \ 390 } while (0) 391 392 #define put_user(x, ptr) \ 393 ({ \ 394 int __pu_err = 0; \ 395 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 396 __pu_err; \ 397 }) 398 399 #ifdef CONFIG_CPU_SPECTRE 400 /* 401 * When mitigating Spectre variant 1.1, all accessors need to include 402 * verification of the address space. 403 */ 404 #define __put_user(x, ptr) put_user(x, ptr) 405 406 #else 407 #define __put_user(x, ptr) \ 408 ({ \ 409 long __pu_err = 0; \ 410 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 411 __pu_err; \ 412 }) 413 414 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 415 do { \ 416 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 417 __put_user_nocheck_##__size(x, __pu_addr, __err); \ 418 } while (0) 419 420 #define __put_user_nocheck_1 __put_user_asm_byte 421 #define __put_user_nocheck_2 __put_user_asm_half 422 #define __put_user_nocheck_4 __put_user_asm_word 423 #define __put_user_nocheck_8 __put_user_asm_dword 424 425 #define __put_user_asm(x, __pu_addr, err, instr) \ 426 __asm__ __volatile__( \ 427 "1: " TUSER(instr) " %1, [%2], #0\n" \ 428 "2:\n" \ 429 " .pushsection .text.fixup,\"ax\"\n" \ 430 " .align 2\n" \ 431 "3: mov %0, %3\n" \ 432 " b 2b\n" \ 433 " .popsection\n" \ 434 " .pushsection __ex_table,\"a\"\n" \ 435 " .align 3\n" \ 436 " .long 1b, 3b\n" \ 437 " .popsection" \ 438 : "+r" (err) \ 439 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 440 : "cc") 441 442 #define __put_user_asm_byte(x, __pu_addr, err) \ 443 __put_user_asm(x, __pu_addr, err, strb) 444 445 #ifndef __ARMEB__ 446 #define __put_user_asm_half(x, __pu_addr, err) \ 447 ({ \ 448 unsigned long __temp = (__force unsigned long)(x); \ 449 __put_user_asm_byte(__temp, __pu_addr, err); \ 450 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \ 451 }) 452 #else 453 #define __put_user_asm_half(x, __pu_addr, err) \ 454 ({ \ 455 unsigned long __temp = (__force unsigned long)(x); \ 456 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \ 457 __put_user_asm_byte(__temp, __pu_addr + 1, err); \ 458 }) 459 #endif 460 461 #define __put_user_asm_word(x, __pu_addr, err) \ 462 __put_user_asm(x, __pu_addr, err, str) 463 464 #ifndef __ARMEB__ 465 #define __reg_oper0 "%R2" 466 #define __reg_oper1 "%Q2" 467 #else 468 #define __reg_oper0 "%Q2" 469 #define __reg_oper1 "%R2" 470 #endif 471 472 #define __put_user_asm_dword(x, __pu_addr, err) \ 473 __asm__ __volatile__( \ 474 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \ 475 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \ 476 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \ 477 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \ 478 "3:\n" \ 479 " .pushsection .text.fixup,\"ax\"\n" \ 480 " .align 2\n" \ 481 "4: mov %0, %3\n" \ 482 " b 3b\n" \ 483 " .popsection\n" \ 484 " .pushsection __ex_table,\"a\"\n" \ 485 " .align 3\n" \ 486 " .long 1b, 4b\n" \ 487 " .long 2b, 4b\n" \ 488 " .popsection" \ 489 : "+r" (err), "+r" (__pu_addr) \ 490 : "r" (x), "i" (-EFAULT) \ 491 : "cc") 492 493 #endif /* !CONFIG_CPU_SPECTRE */ 494 495 #ifdef CONFIG_MMU 496 extern unsigned long __must_check 497 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 498 499 static inline unsigned long __must_check 500 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 501 { 502 unsigned int __ua_flags; 503 504 __ua_flags = uaccess_save_and_enable(); 505 n = arm_copy_from_user(to, from, n); 506 uaccess_restore(__ua_flags); 507 return n; 508 } 509 510 extern unsigned long __must_check 511 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 512 extern unsigned long __must_check 513 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 514 515 static inline unsigned long __must_check 516 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 517 { 518 #ifndef CONFIG_UACCESS_WITH_MEMCPY 519 unsigned int __ua_flags; 520 __ua_flags = uaccess_save_and_enable(); 521 n = arm_copy_to_user(to, from, n); 522 uaccess_restore(__ua_flags); 523 return n; 524 #else 525 return arm_copy_to_user(to, from, n); 526 #endif 527 } 528 529 extern unsigned long __must_check 530 arm_clear_user(void __user *addr, unsigned long n); 531 extern unsigned long __must_check 532 __clear_user_std(void __user *addr, unsigned long n); 533 534 static inline unsigned long __must_check 535 __clear_user(void __user *addr, unsigned long n) 536 { 537 unsigned int __ua_flags = uaccess_save_and_enable(); 538 n = arm_clear_user(addr, n); 539 uaccess_restore(__ua_flags); 540 return n; 541 } 542 543 #else 544 static inline unsigned long 545 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 546 { 547 memcpy(to, (const void __force *)from, n); 548 return 0; 549 } 550 static inline unsigned long 551 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 552 { 553 memcpy((void __force *)to, from, n); 554 return 0; 555 } 556 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 557 #endif 558 #define INLINE_COPY_TO_USER 559 #define INLINE_COPY_FROM_USER 560 561 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 562 { 563 if (access_ok(VERIFY_WRITE, to, n)) 564 n = __clear_user(to, n); 565 return n; 566 } 567 568 /* These are from lib/ code, and use __get_user() and friends */ 569 extern long strncpy_from_user(char *dest, const char __user *src, long count); 570 571 extern __must_check long strnlen_user(const char __user *str, long n); 572 573 #endif /* _ASMARM_UACCESS_H */ 574