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 modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); 73 } 74 75 #define segment_eq(a, b) ((a) == (b)) 76 77 /* We use 33-bit arithmetic here... */ 78 #define __range_ok(addr, size) ({ \ 79 unsigned long flag, roksum; \ 80 __chk_user_ptr(addr); \ 81 __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \ 82 : "=&r" (flag), "=&r" (roksum) \ 83 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ 84 : "cc"); \ 85 flag; }) 86 87 /* 88 * This is a type: either unsigned long, if the argument fits into 89 * that type, or otherwise unsigned long long. 90 */ 91 #define __inttype(x) \ 92 __typeof__(__builtin_choose_expr(sizeof(x) > sizeof(0UL), 0ULL, 0UL)) 93 94 /* 95 * Single-value transfer routines. They automatically use the right 96 * size if we just have the right pointer type. Note that the functions 97 * which read from user space (*get_*) need to take care not to leak 98 * kernel data even if the calling code is buggy and fails to check 99 * the return value. This means zeroing out the destination variable 100 * or buffer on error. Normally this is done out of line by the 101 * fixup code, but there are a few places where it intrudes on the 102 * main code path. When we only write to user space, there is no 103 * problem. 104 */ 105 extern int __get_user_1(void *); 106 extern int __get_user_2(void *); 107 extern int __get_user_4(void *); 108 extern int __get_user_32t_8(void *); 109 extern int __get_user_8(void *); 110 extern int __get_user_64t_1(void *); 111 extern int __get_user_64t_2(void *); 112 extern int __get_user_64t_4(void *); 113 114 #define __GUP_CLOBBER_1 "lr", "cc" 115 #ifdef CONFIG_CPU_USE_DOMAINS 116 #define __GUP_CLOBBER_2 "ip", "lr", "cc" 117 #else 118 #define __GUP_CLOBBER_2 "lr", "cc" 119 #endif 120 #define __GUP_CLOBBER_4 "lr", "cc" 121 #define __GUP_CLOBBER_32t_8 "lr", "cc" 122 #define __GUP_CLOBBER_8 "lr", "cc" 123 124 #define __get_user_x(__r2, __p, __e, __l, __s) \ 125 __asm__ __volatile__ ( \ 126 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 127 __asmeq("%3", "r1") \ 128 "bl __get_user_" #__s \ 129 : "=&r" (__e), "=r" (__r2) \ 130 : "0" (__p), "r" (__l) \ 131 : __GUP_CLOBBER_##__s) 132 133 /* narrowing a double-word get into a single 32bit word register: */ 134 #ifdef __ARMEB__ 135 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 136 __get_user_x(__r2, __p, __e, __l, 32t_8) 137 #else 138 #define __get_user_x_32t __get_user_x 139 #endif 140 141 /* 142 * storing result into proper least significant word of 64bit target var, 143 * different only for big endian case where 64 bit __r2 lsw is r3: 144 */ 145 #ifdef __ARMEB__ 146 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 147 __asm__ __volatile__ ( \ 148 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 149 __asmeq("%3", "r1") \ 150 "bl __get_user_64t_" #__s \ 151 : "=&r" (__e), "=r" (__r2) \ 152 : "0" (__p), "r" (__l) \ 153 : __GUP_CLOBBER_##__s) 154 #else 155 #define __get_user_x_64t __get_user_x 156 #endif 157 158 159 #define __get_user_check(x, p) \ 160 ({ \ 161 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 162 register typeof(*(p)) __user *__p asm("r0") = (p); \ 163 register __inttype(x) __r2 asm("r2"); \ 164 register unsigned long __l asm("r1") = __limit; \ 165 register int __e asm("r0"); \ 166 unsigned int __ua_flags = uaccess_save_and_enable(); \ 167 switch (sizeof(*(__p))) { \ 168 case 1: \ 169 if (sizeof((x)) >= 8) \ 170 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 171 else \ 172 __get_user_x(__r2, __p, __e, __l, 1); \ 173 break; \ 174 case 2: \ 175 if (sizeof((x)) >= 8) \ 176 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 177 else \ 178 __get_user_x(__r2, __p, __e, __l, 2); \ 179 break; \ 180 case 4: \ 181 if (sizeof((x)) >= 8) \ 182 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 183 else \ 184 __get_user_x(__r2, __p, __e, __l, 4); \ 185 break; \ 186 case 8: \ 187 if (sizeof((x)) < 8) \ 188 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 189 else \ 190 __get_user_x(__r2, __p, __e, __l, 8); \ 191 break; \ 192 default: __e = __get_user_bad(); break; \ 193 } \ 194 uaccess_restore(__ua_flags); \ 195 x = (typeof(*(p))) __r2; \ 196 __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 = current_thread_info()->addr_limit - 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 /* 230 * uClinux has only one addr space, so has simplified address limits. 231 */ 232 #define USER_DS KERNEL_DS 233 234 #define segment_eq(a, b) (1) 235 #define __addr_ok(addr) ((void)(addr), 1) 236 #define __range_ok(addr, size) ((void)(addr), 0) 237 #define get_fs() (KERNEL_DS) 238 239 static inline void set_fs(mm_segment_t fs) 240 { 241 } 242 243 #define get_user(x, p) __get_user(x, p) 244 #define __put_user_check __put_user_nocheck 245 246 #endif /* CONFIG_MMU */ 247 248 #define access_ok(type, addr, size) (__range_ok(addr, size) == 0) 249 250 #define user_addr_max() \ 251 (uaccess_kernel() ? ~0UL : get_fs()) 252 253 #ifdef CONFIG_CPU_SPECTRE 254 /* 255 * When mitigating Spectre variant 1, it is not worth fixing the non- 256 * verifying accessors, because we need to add verification of the 257 * address space there. Force these to use the standard get_user() 258 * version instead. 259 */ 260 #define __get_user(x, ptr) get_user(x, ptr) 261 #else 262 263 /* 264 * The "__xxx" versions of the user access functions do not verify the 265 * address space - it must have been done previously with a separate 266 * "access_ok()" call. 267 * 268 * The "xxx_error" versions set the third argument to EFAULT if an 269 * error occurs, and leave it unchanged on success. Note that these 270 * versions are void (ie, don't return a value as such). 271 */ 272 #define __get_user(x, ptr) \ 273 ({ \ 274 long __gu_err = 0; \ 275 __get_user_err((x), (ptr), __gu_err); \ 276 __gu_err; \ 277 }) 278 279 #define __get_user_err(x, ptr, err) \ 280 do { \ 281 unsigned long __gu_addr = (unsigned long)(ptr); \ 282 unsigned long __gu_val; \ 283 unsigned int __ua_flags; \ 284 __chk_user_ptr(ptr); \ 285 might_fault(); \ 286 __ua_flags = uaccess_save_and_enable(); \ 287 switch (sizeof(*(ptr))) { \ 288 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \ 289 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \ 290 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \ 291 default: (__gu_val) = __get_user_bad(); \ 292 } \ 293 uaccess_restore(__ua_flags); \ 294 (x) = (__typeof__(*(ptr)))__gu_val; \ 295 } while (0) 296 297 #define __get_user_asm(x, addr, err, instr) \ 298 __asm__ __volatile__( \ 299 "1: " TUSER(instr) " %1, [%2], #0\n" \ 300 "2:\n" \ 301 " .pushsection .text.fixup,\"ax\"\n" \ 302 " .align 2\n" \ 303 "3: mov %0, %3\n" \ 304 " mov %1, #0\n" \ 305 " b 2b\n" \ 306 " .popsection\n" \ 307 " .pushsection __ex_table,\"a\"\n" \ 308 " .align 3\n" \ 309 " .long 1b, 3b\n" \ 310 " .popsection" \ 311 : "+r" (err), "=&r" (x) \ 312 : "r" (addr), "i" (-EFAULT) \ 313 : "cc") 314 315 #define __get_user_asm_byte(x, addr, err) \ 316 __get_user_asm(x, addr, err, ldrb) 317 318 #ifndef __ARMEB__ 319 #define __get_user_asm_half(x, __gu_addr, err) \ 320 ({ \ 321 unsigned long __b1, __b2; \ 322 __get_user_asm_byte(__b1, __gu_addr, err); \ 323 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 324 (x) = __b1 | (__b2 << 8); \ 325 }) 326 #else 327 #define __get_user_asm_half(x, __gu_addr, err) \ 328 ({ \ 329 unsigned long __b1, __b2; \ 330 __get_user_asm_byte(__b1, __gu_addr, err); \ 331 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 332 (x) = (__b1 << 8) | __b2; \ 333 }) 334 #endif 335 336 #define __get_user_asm_word(x, addr, err) \ 337 __get_user_asm(x, addr, err, ldr) 338 #endif 339 340 341 #define __put_user_switch(x, ptr, __err, __fn) \ 342 do { \ 343 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 344 __typeof__(*(ptr)) __pu_val = (x); \ 345 unsigned int __ua_flags; \ 346 might_fault(); \ 347 __ua_flags = uaccess_save_and_enable(); \ 348 switch (sizeof(*(ptr))) { \ 349 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 350 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 351 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 352 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 353 default: __err = __put_user_bad(); break; \ 354 } \ 355 uaccess_restore(__ua_flags); \ 356 } while (0) 357 358 #define put_user(x, ptr) \ 359 ({ \ 360 int __pu_err = 0; \ 361 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 362 __pu_err; \ 363 }) 364 365 #define __put_user(x, ptr) \ 366 ({ \ 367 long __pu_err = 0; \ 368 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 369 __pu_err; \ 370 }) 371 372 #define __put_user_error(x, ptr, err) \ 373 ({ \ 374 __put_user_switch((x), (ptr), (err), __put_user_nocheck); \ 375 (void) 0; \ 376 }) 377 378 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 379 do { \ 380 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 381 __put_user_nocheck_##__size(x, __pu_addr, __err); \ 382 } while (0) 383 384 #define __put_user_nocheck_1 __put_user_asm_byte 385 #define __put_user_nocheck_2 __put_user_asm_half 386 #define __put_user_nocheck_4 __put_user_asm_word 387 #define __put_user_nocheck_8 __put_user_asm_dword 388 389 #define __put_user_asm(x, __pu_addr, err, instr) \ 390 __asm__ __volatile__( \ 391 "1: " TUSER(instr) " %1, [%2], #0\n" \ 392 "2:\n" \ 393 " .pushsection .text.fixup,\"ax\"\n" \ 394 " .align 2\n" \ 395 "3: mov %0, %3\n" \ 396 " b 2b\n" \ 397 " .popsection\n" \ 398 " .pushsection __ex_table,\"a\"\n" \ 399 " .align 3\n" \ 400 " .long 1b, 3b\n" \ 401 " .popsection" \ 402 : "+r" (err) \ 403 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 404 : "cc") 405 406 #define __put_user_asm_byte(x, __pu_addr, err) \ 407 __put_user_asm(x, __pu_addr, err, strb) 408 409 #ifndef __ARMEB__ 410 #define __put_user_asm_half(x, __pu_addr, err) \ 411 ({ \ 412 unsigned long __temp = (__force unsigned long)(x); \ 413 __put_user_asm_byte(__temp, __pu_addr, err); \ 414 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \ 415 }) 416 #else 417 #define __put_user_asm_half(x, __pu_addr, err) \ 418 ({ \ 419 unsigned long __temp = (__force unsigned long)(x); \ 420 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \ 421 __put_user_asm_byte(__temp, __pu_addr + 1, err); \ 422 }) 423 #endif 424 425 #define __put_user_asm_word(x, __pu_addr, err) \ 426 __put_user_asm(x, __pu_addr, err, str) 427 428 #ifndef __ARMEB__ 429 #define __reg_oper0 "%R2" 430 #define __reg_oper1 "%Q2" 431 #else 432 #define __reg_oper0 "%Q2" 433 #define __reg_oper1 "%R2" 434 #endif 435 436 #define __put_user_asm_dword(x, __pu_addr, err) \ 437 __asm__ __volatile__( \ 438 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \ 439 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \ 440 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \ 441 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \ 442 "3:\n" \ 443 " .pushsection .text.fixup,\"ax\"\n" \ 444 " .align 2\n" \ 445 "4: mov %0, %3\n" \ 446 " b 3b\n" \ 447 " .popsection\n" \ 448 " .pushsection __ex_table,\"a\"\n" \ 449 " .align 3\n" \ 450 " .long 1b, 4b\n" \ 451 " .long 2b, 4b\n" \ 452 " .popsection" \ 453 : "+r" (err), "+r" (__pu_addr) \ 454 : "r" (x), "i" (-EFAULT) \ 455 : "cc") 456 457 458 #ifdef CONFIG_MMU 459 extern unsigned long __must_check 460 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 461 462 static inline unsigned long __must_check 463 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 464 { 465 unsigned int __ua_flags; 466 467 __ua_flags = uaccess_save_and_enable(); 468 n = arm_copy_from_user(to, from, n); 469 uaccess_restore(__ua_flags); 470 return n; 471 } 472 473 extern unsigned long __must_check 474 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 475 extern unsigned long __must_check 476 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 477 478 static inline unsigned long __must_check 479 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 480 { 481 #ifndef CONFIG_UACCESS_WITH_MEMCPY 482 unsigned int __ua_flags; 483 __ua_flags = uaccess_save_and_enable(); 484 n = arm_copy_to_user(to, from, n); 485 uaccess_restore(__ua_flags); 486 return n; 487 #else 488 return arm_copy_to_user(to, from, n); 489 #endif 490 } 491 492 extern unsigned long __must_check 493 arm_clear_user(void __user *addr, unsigned long n); 494 extern unsigned long __must_check 495 __clear_user_std(void __user *addr, unsigned long n); 496 497 static inline unsigned long __must_check 498 __clear_user(void __user *addr, unsigned long n) 499 { 500 unsigned int __ua_flags = uaccess_save_and_enable(); 501 n = arm_clear_user(addr, n); 502 uaccess_restore(__ua_flags); 503 return n; 504 } 505 506 #else 507 static inline unsigned long 508 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 509 { 510 memcpy(to, (const void __force *)from, n); 511 return 0; 512 } 513 static inline unsigned long 514 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 515 { 516 memcpy((void __force *)to, from, n); 517 return 0; 518 } 519 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 520 #endif 521 #define INLINE_COPY_TO_USER 522 #define INLINE_COPY_FROM_USER 523 524 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 525 { 526 if (access_ok(VERIFY_WRITE, to, n)) 527 n = __clear_user(to, n); 528 return n; 529 } 530 531 /* These are from lib/ code, and use __get_user() and friends */ 532 extern long strncpy_from_user(char *dest, const char __user *src, long count); 533 534 extern __must_check long strnlen_user(const char __user *str, long n); 535 536 #endif /* _ASMARM_UACCESS_H */ 537