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 */ 25static __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 40static __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 */ 52extern int __get_user_bad(void); 53extern int __put_user_bad(void); 54 55/* 56 * Note that this is actually 0x1,0000,0000 57 */ 58#define KERNEL_DS 0x00000000 59 60#ifdef CONFIG_MMU 61 62#define USER_DS TASK_SIZE 63#define get_fs() (current_thread_info()->addr_limit) 64 65static inline void set_fs(mm_segment_t fs) 66{ 67 current_thread_info()->addr_limit = fs; 68 69 /* 70 * Prevent a mispredicted conditional call to set_fs from forwarding 71 * the wrong address limit to access_ok under speculation. 72 */ 73 dsb(nsh); 74 isb(); 75 76 modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); 77} 78 79#define uaccess_kernel() (get_fs() == KERNEL_DS) 80 81/* 82 * We use 33-bit arithmetic here. Success returns zero, failure returns 83 * addr_limit. We take advantage that addr_limit will be zero for KERNEL_DS, 84 * so this will always return success in that case. 85 */ 86#define __range_ok(addr, size) ({ \ 87 unsigned long flag, roksum; \ 88 __chk_user_ptr(addr); \ 89 __asm__(".syntax unified\n" \ 90 "adds %1, %2, %3; sbcscc %1, %1, %0; movcc %0, #0" \ 91 : "=&r" (flag), "=&r" (roksum) \ 92 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ 93 : "cc"); \ 94 flag; }) 95 96/* 97 * This is a type: either unsigned long, if the argument fits into 98 * that type, or otherwise unsigned long long. 99 */ 100#define __inttype(x) \ 101 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 102 103/* 104 * Sanitise a uaccess pointer such that it becomes NULL if addr+size 105 * is above the current addr_limit. 106 */ 107#define uaccess_mask_range_ptr(ptr, size) \ 108 ((__typeof__(ptr))__uaccess_mask_range_ptr(ptr, size)) 109static inline void __user *__uaccess_mask_range_ptr(const void __user *ptr, 110 size_t size) 111{ 112 void __user *safe_ptr = (void __user *)ptr; 113 unsigned long tmp; 114 115 asm volatile( 116 " .syntax unified\n" 117 " sub %1, %3, #1\n" 118 " subs %1, %1, %0\n" 119 " addhs %1, %1, #1\n" 120 " subshs %1, %1, %2\n" 121 " movlo %0, #0\n" 122 : "+r" (safe_ptr), "=&r" (tmp) 123 : "r" (size), "r" (current_thread_info()->addr_limit) 124 : "cc"); 125 126 csdb(); 127 return safe_ptr; 128} 129 130/* 131 * Single-value transfer routines. They automatically use the right 132 * size if we just have the right pointer type. Note that the functions 133 * which read from user space (*get_*) need to take care not to leak 134 * kernel data even if the calling code is buggy and fails to check 135 * the return value. This means zeroing out the destination variable 136 * or buffer on error. Normally this is done out of line by the 137 * fixup code, but there are a few places where it intrudes on the 138 * main code path. When we only write to user space, there is no 139 * problem. 140 */ 141extern int __get_user_1(void *); 142extern int __get_user_2(void *); 143extern int __get_user_4(void *); 144extern int __get_user_32t_8(void *); 145extern int __get_user_8(void *); 146extern int __get_user_64t_1(void *); 147extern int __get_user_64t_2(void *); 148extern int __get_user_64t_4(void *); 149 150#define __GUP_CLOBBER_1 "lr", "cc" 151#ifdef CONFIG_CPU_USE_DOMAINS 152#define __GUP_CLOBBER_2 "ip", "lr", "cc" 153#else 154#define __GUP_CLOBBER_2 "lr", "cc" 155#endif 156#define __GUP_CLOBBER_4 "lr", "cc" 157#define __GUP_CLOBBER_32t_8 "lr", "cc" 158#define __GUP_CLOBBER_8 "lr", "cc" 159 160#define __get_user_x(__r2, __p, __e, __l, __s) \ 161 __asm__ __volatile__ ( \ 162 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 163 __asmeq("%3", "r1") \ 164 "bl __get_user_" #__s \ 165 : "=&r" (__e), "=r" (__r2) \ 166 : "0" (__p), "r" (__l) \ 167 : __GUP_CLOBBER_##__s) 168 169/* narrowing a double-word get into a single 32bit word register: */ 170#ifdef __ARMEB__ 171#define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 172 __get_user_x(__r2, __p, __e, __l, 32t_8) 173#else 174#define __get_user_x_32t __get_user_x 175#endif 176 177/* 178 * storing result into proper least significant word of 64bit target var, 179 * different only for big endian case where 64 bit __r2 lsw is r3: 180 */ 181#ifdef __ARMEB__ 182#define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 183 __asm__ __volatile__ ( \ 184 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 185 __asmeq("%3", "r1") \ 186 "bl __get_user_64t_" #__s \ 187 : "=&r" (__e), "=r" (__r2) \ 188 : "0" (__p), "r" (__l) \ 189 : __GUP_CLOBBER_##__s) 190#else 191#define __get_user_x_64t __get_user_x 192#endif 193 194 195#define __get_user_check(x, p) \ 196 ({ \ 197 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 198 register typeof(*(p)) __user *__p asm("r0") = (p); \ 199 register __inttype(x) __r2 asm("r2"); \ 200 register unsigned long __l asm("r1") = __limit; \ 201 register int __e asm("r0"); \ 202 unsigned int __ua_flags = uaccess_save_and_enable(); \ 203 int __tmp_e; \ 204 switch (sizeof(*(__p))) { \ 205 case 1: \ 206 if (sizeof((x)) >= 8) \ 207 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 208 else \ 209 __get_user_x(__r2, __p, __e, __l, 1); \ 210 break; \ 211 case 2: \ 212 if (sizeof((x)) >= 8) \ 213 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 214 else \ 215 __get_user_x(__r2, __p, __e, __l, 2); \ 216 break; \ 217 case 4: \ 218 if (sizeof((x)) >= 8) \ 219 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 220 else \ 221 __get_user_x(__r2, __p, __e, __l, 4); \ 222 break; \ 223 case 8: \ 224 if (sizeof((x)) < 8) \ 225 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 226 else \ 227 __get_user_x(__r2, __p, __e, __l, 8); \ 228 break; \ 229 default: __e = __get_user_bad(); break; \ 230 } \ 231 __tmp_e = __e; \ 232 uaccess_restore(__ua_flags); \ 233 x = (typeof(*(p))) __r2; \ 234 __tmp_e; \ 235 }) 236 237#define get_user(x, p) \ 238 ({ \ 239 might_fault(); \ 240 __get_user_check(x, p); \ 241 }) 242 243extern int __put_user_1(void *, unsigned int); 244extern int __put_user_2(void *, unsigned int); 245extern int __put_user_4(void *, unsigned int); 246extern int __put_user_8(void *, unsigned long long); 247 248#define __put_user_check(__pu_val, __ptr, __err, __s) \ 249 ({ \ 250 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 251 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 252 register const void __user *__p asm("r0") = __ptr; \ 253 register unsigned long __l asm("r1") = __limit; \ 254 register int __e asm("r0"); \ 255 __asm__ __volatile__ ( \ 256 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 257 __asmeq("%3", "r1") \ 258 "bl __put_user_" #__s \ 259 : "=&r" (__e) \ 260 : "0" (__p), "r" (__r2), "r" (__l) \ 261 : "ip", "lr", "cc"); \ 262 __err = __e; \ 263 }) 264 265#else /* CONFIG_MMU */ 266 267/* 268 * uClinux has only one addr space, so has simplified address limits. 269 */ 270#define USER_DS KERNEL_DS 271 272#define uaccess_kernel() (true) 273#define __addr_ok(addr) ((void)(addr), 1) 274#define __range_ok(addr, size) ((void)(addr), 0) 275#define get_fs() (KERNEL_DS) 276 277static inline void set_fs(mm_segment_t fs) 278{ 279} 280 281#define get_user(x, p) __get_user(x, p) 282#define __put_user_check __put_user_nocheck 283 284#endif /* CONFIG_MMU */ 285 286#define access_ok(addr, size) (__range_ok(addr, size) == 0) 287 288#define user_addr_max() \ 289 (uaccess_kernel() ? ~0UL : get_fs()) 290 291#ifdef CONFIG_CPU_SPECTRE 292/* 293 * When mitigating Spectre variant 1, it is not worth fixing the non- 294 * verifying accessors, because we need to add verification of the 295 * address space there. Force these to use the standard get_user() 296 * version instead. 297 */ 298#define __get_user(x, ptr) get_user(x, ptr) 299#else 300 301/* 302 * The "__xxx" versions of the user access functions do not verify the 303 * address space - it must have been done previously with a separate 304 * "access_ok()" call. 305 * 306 * The "xxx_error" versions set the third argument to EFAULT if an 307 * error occurs, and leave it unchanged on success. Note that these 308 * versions are void (ie, don't return a value as such). 309 */ 310#define __get_user(x, ptr) \ 311({ \ 312 long __gu_err = 0; \ 313 __get_user_err((x), (ptr), __gu_err); \ 314 __gu_err; \ 315}) 316 317#define __get_user_err(x, ptr, err) \ 318do { \ 319 unsigned long __gu_addr = (unsigned long)(ptr); \ 320 unsigned long __gu_val; \ 321 unsigned int __ua_flags; \ 322 __chk_user_ptr(ptr); \ 323 might_fault(); \ 324 __ua_flags = uaccess_save_and_enable(); \ 325 switch (sizeof(*(ptr))) { \ 326 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \ 327 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \ 328 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \ 329 default: (__gu_val) = __get_user_bad(); \ 330 } \ 331 uaccess_restore(__ua_flags); \ 332 (x) = (__typeof__(*(ptr)))__gu_val; \ 333} while (0) 334 335#define __get_user_asm(x, addr, err, instr) \ 336 __asm__ __volatile__( \ 337 "1: " TUSER(instr) " %1, [%2], #0\n" \ 338 "2:\n" \ 339 " .pushsection .text.fixup,\"ax\"\n" \ 340 " .align 2\n" \ 341 "3: mov %0, %3\n" \ 342 " mov %1, #0\n" \ 343 " b 2b\n" \ 344 " .popsection\n" \ 345 " ex_entry 1b, 3b\n" \ 346 : "+r" (err), "=&r" (x) \ 347 : "r" (addr), "i" (-EFAULT) \ 348 : "cc") 349 350#define __get_user_asm_byte(x, addr, err) \ 351 __get_user_asm(x, addr, err, ldrb) 352 353#if __LINUX_ARM_ARCH__ >= 6 354 355#define __get_user_asm_half(x, addr, err) \ 356 __get_user_asm(x, addr, err, ldrh) 357 358#else 359 360#ifndef __ARMEB__ 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 | (__b2 << 8); \ 367}) 368#else 369#define __get_user_asm_half(x, __gu_addr, err) \ 370({ \ 371 unsigned long __b1, __b2; \ 372 __get_user_asm_byte(__b1, __gu_addr, err); \ 373 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 374 (x) = (__b1 << 8) | __b2; \ 375}) 376#endif 377 378#endif /* __LINUX_ARM_ARCH__ >= 6 */ 379 380#define __get_user_asm_word(x, addr, err) \ 381 __get_user_asm(x, addr, err, ldr) 382#endif 383 384 385#define __put_user_switch(x, ptr, __err, __fn) \ 386 do { \ 387 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 388 __typeof__(*(ptr)) __pu_val = (x); \ 389 unsigned int __ua_flags; \ 390 might_fault(); \ 391 __ua_flags = uaccess_save_and_enable(); \ 392 switch (sizeof(*(ptr))) { \ 393 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 394 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 395 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 396 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 397 default: __err = __put_user_bad(); break; \ 398 } \ 399 uaccess_restore(__ua_flags); \ 400 } while (0) 401 402#define put_user(x, ptr) \ 403({ \ 404 int __pu_err = 0; \ 405 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 406 __pu_err; \ 407}) 408 409#ifdef CONFIG_CPU_SPECTRE 410/* 411 * When mitigating Spectre variant 1.1, all accessors need to include 412 * verification of the address space. 413 */ 414#define __put_user(x, ptr) put_user(x, ptr) 415 416#else 417#define __put_user(x, ptr) \ 418({ \ 419 long __pu_err = 0; \ 420 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 421 __pu_err; \ 422}) 423 424#define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 425 do { \ 426 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 427 __put_user_nocheck_##__size(x, __pu_addr, __err); \ 428 } while (0) 429 430#define __put_user_nocheck_1 __put_user_asm_byte 431#define __put_user_nocheck_2 __put_user_asm_half 432#define __put_user_nocheck_4 __put_user_asm_word 433#define __put_user_nocheck_8 __put_user_asm_dword 434 435#define __put_user_asm(x, __pu_addr, err, instr) \ 436 __asm__ __volatile__( \ 437 "1: " TUSER(instr) " %1, [%2], #0\n" \ 438 "2:\n" \ 439 " .pushsection .text.fixup,\"ax\"\n" \ 440 " .align 2\n" \ 441 "3: mov %0, %3\n" \ 442 " b 2b\n" \ 443 " .popsection\n" \ 444 " ex_entry 1b, 3b\n" \ 445 : "+r" (err) \ 446 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 447 : "cc") 448 449#define __put_user_asm_byte(x, __pu_addr, err) \ 450 __put_user_asm(x, __pu_addr, err, strb) 451 452#if __LINUX_ARM_ARCH__ >= 6 453 454#define __put_user_asm_half(x, __pu_addr, err) \ 455 __put_user_asm(x, __pu_addr, err, strh) 456 457#else 458 459#ifndef __ARMEB__ 460#define __put_user_asm_half(x, __pu_addr, err) \ 461({ \ 462 unsigned long __temp = (__force unsigned long)(x); \ 463 __put_user_asm_byte(__temp, __pu_addr, err); \ 464 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \ 465}) 466#else 467#define __put_user_asm_half(x, __pu_addr, err) \ 468({ \ 469 unsigned long __temp = (__force unsigned long)(x); \ 470 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \ 471 __put_user_asm_byte(__temp, __pu_addr + 1, err); \ 472}) 473#endif 474 475#endif /* __LINUX_ARM_ARCH__ >= 6 */ 476 477#define __put_user_asm_word(x, __pu_addr, err) \ 478 __put_user_asm(x, __pu_addr, err, str) 479 480#ifndef __ARMEB__ 481#define __reg_oper0 "%R2" 482#define __reg_oper1 "%Q2" 483#else 484#define __reg_oper0 "%Q2" 485#define __reg_oper1 "%R2" 486#endif 487 488#define __put_user_asm_dword(x, __pu_addr, err) \ 489 __asm__ __volatile__( \ 490 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \ 491 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \ 492 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \ 493 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \ 494 "3:\n" \ 495 " .pushsection .text.fixup,\"ax\"\n" \ 496 " .align 2\n" \ 497 "4: mov %0, %3\n" \ 498 " b 3b\n" \ 499 " .popsection\n" \ 500 " ex_entry 1b, 4b\n" \ 501 " ex_entry 2b, 4b\n" \ 502 : "+r" (err), "+r" (__pu_addr) \ 503 : "r" (x), "i" (-EFAULT) \ 504 : "cc") 505 506#endif /* !CONFIG_CPU_SPECTRE */ 507 508#ifdef CONFIG_MMU 509extern unsigned long __must_check 510arm_copy_from_user(void *to, const void __user *from, unsigned long n); 511 512static inline unsigned long __must_check 513raw_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 523extern unsigned long __must_check 524arm_copy_to_user(void __user *to, const void *from, unsigned long n); 525extern unsigned long __must_check 526__copy_to_user_std(void __user *to, const void *from, unsigned long n); 527 528static inline unsigned long __must_check 529raw_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 542extern unsigned long __must_check 543arm_clear_user(void __user *addr, unsigned long n); 544extern unsigned long __must_check 545__clear_user_std(void __user *addr, unsigned long n); 546 547static 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 557static inline unsigned long 558raw_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} 563static inline unsigned long 564raw_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 574static 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 */ 582extern long strncpy_from_user(char *dest, const char __user *src, long count); 583 584extern __must_check long strnlen_user(const char __user *str, long n); 585 586#endif /* _ASMARM_UACCESS_H */ 587