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 #ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS 21 #include <asm-generic/uaccess-unaligned.h> 22 #else 23 #define __get_user_unaligned __get_user 24 #define __put_user_unaligned __put_user 25 #endif 26 27 /* 28 * The exception table consists of pairs of addresses: the first is the 29 * address of an instruction that is allowed to fault, and the second is 30 * the address at which the program should continue. No registers are 31 * modified, so it is entirely up to the continuation code to figure out 32 * what to do. 33 * 34 * All the routines below use bits of fixup code that are out of line 35 * with the main instruction path. This means when everything is well, 36 * we don't even have to jump over them. Further, they do not intrude 37 * on our cache or tlb entries. 38 */ 39 40 struct exception_table_entry 41 { 42 unsigned long insn, fixup; 43 }; 44 45 extern int fixup_exception(struct pt_regs *regs); 46 47 /* 48 * These two functions allow hooking accesses to userspace to increase 49 * system integrity by ensuring that the kernel can not inadvertantly 50 * perform such accesses (eg, via list poison values) which could then 51 * be exploited for priviledge escalation. 52 */ 53 static inline unsigned int uaccess_save_and_enable(void) 54 { 55 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 56 unsigned int old_domain = get_domain(); 57 58 /* Set the current domain access to permit user accesses */ 59 set_domain((old_domain & ~domain_mask(DOMAIN_USER)) | 60 domain_val(DOMAIN_USER, DOMAIN_CLIENT)); 61 62 return old_domain; 63 #else 64 return 0; 65 #endif 66 } 67 68 static inline void uaccess_restore(unsigned int flags) 69 { 70 #ifdef CONFIG_CPU_SW_DOMAIN_PAN 71 /* Restore the user access mask */ 72 set_domain(flags); 73 #endif 74 } 75 76 /* 77 * These two are intentionally not defined anywhere - if the kernel 78 * code generates any references to them, that's a bug. 79 */ 80 extern int __get_user_bad(void); 81 extern int __put_user_bad(void); 82 83 /* 84 * Note that this is actually 0x1,0000,0000 85 */ 86 #define KERNEL_DS 0x00000000 87 #define get_ds() (KERNEL_DS) 88 89 #ifdef CONFIG_MMU 90 91 #define USER_DS TASK_SIZE 92 #define get_fs() (current_thread_info()->addr_limit) 93 94 static inline void set_fs(mm_segment_t fs) 95 { 96 current_thread_info()->addr_limit = fs; 97 modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); 98 } 99 100 #define segment_eq(a, b) ((a) == (b)) 101 102 /* We use 33-bit arithmetic here... */ 103 #define __range_ok(addr, size) ({ \ 104 unsigned long flag, roksum; \ 105 __chk_user_ptr(addr); \ 106 __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \ 107 : "=&r" (flag), "=&r" (roksum) \ 108 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ 109 : "cc"); \ 110 flag; }) 111 112 /* 113 * Single-value transfer routines. They automatically use the right 114 * size if we just have the right pointer type. Note that the functions 115 * which read from user space (*get_*) need to take care not to leak 116 * kernel data even if the calling code is buggy and fails to check 117 * the return value. This means zeroing out the destination variable 118 * or buffer on error. Normally this is done out of line by the 119 * fixup code, but there are a few places where it intrudes on the 120 * main code path. When we only write to user space, there is no 121 * problem. 122 */ 123 extern int __get_user_1(void *); 124 extern int __get_user_2(void *); 125 extern int __get_user_4(void *); 126 extern int __get_user_32t_8(void *); 127 extern int __get_user_8(void *); 128 extern int __get_user_64t_1(void *); 129 extern int __get_user_64t_2(void *); 130 extern int __get_user_64t_4(void *); 131 132 #define __GUP_CLOBBER_1 "lr", "cc" 133 #ifdef CONFIG_CPU_USE_DOMAINS 134 #define __GUP_CLOBBER_2 "ip", "lr", "cc" 135 #else 136 #define __GUP_CLOBBER_2 "lr", "cc" 137 #endif 138 #define __GUP_CLOBBER_4 "lr", "cc" 139 #define __GUP_CLOBBER_32t_8 "lr", "cc" 140 #define __GUP_CLOBBER_8 "lr", "cc" 141 142 #define __get_user_x(__r2, __p, __e, __l, __s) \ 143 __asm__ __volatile__ ( \ 144 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 145 __asmeq("%3", "r1") \ 146 "bl __get_user_" #__s \ 147 : "=&r" (__e), "=r" (__r2) \ 148 : "0" (__p), "r" (__l) \ 149 : __GUP_CLOBBER_##__s) 150 151 /* narrowing a double-word get into a single 32bit word register: */ 152 #ifdef __ARMEB__ 153 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 154 __get_user_x(__r2, __p, __e, __l, 32t_8) 155 #else 156 #define __get_user_x_32t __get_user_x 157 #endif 158 159 /* 160 * storing result into proper least significant word of 64bit target var, 161 * different only for big endian case where 64 bit __r2 lsw is r3: 162 */ 163 #ifdef __ARMEB__ 164 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 165 __asm__ __volatile__ ( \ 166 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 167 __asmeq("%3", "r1") \ 168 "bl __get_user_64t_" #__s \ 169 : "=&r" (__e), "=r" (__r2) \ 170 : "0" (__p), "r" (__l) \ 171 : __GUP_CLOBBER_##__s) 172 #else 173 #define __get_user_x_64t __get_user_x 174 #endif 175 176 177 #define __get_user_check(x, p) \ 178 ({ \ 179 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 180 register const typeof(*(p)) __user *__p asm("r0") = (p);\ 181 register typeof(x) __r2 asm("r2"); \ 182 register unsigned long __l asm("r1") = __limit; \ 183 register int __e asm("r0"); \ 184 unsigned int __ua_flags = uaccess_save_and_enable(); \ 185 switch (sizeof(*(__p))) { \ 186 case 1: \ 187 if (sizeof((x)) >= 8) \ 188 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 189 else \ 190 __get_user_x(__r2, __p, __e, __l, 1); \ 191 break; \ 192 case 2: \ 193 if (sizeof((x)) >= 8) \ 194 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 195 else \ 196 __get_user_x(__r2, __p, __e, __l, 2); \ 197 break; \ 198 case 4: \ 199 if (sizeof((x)) >= 8) \ 200 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 201 else \ 202 __get_user_x(__r2, __p, __e, __l, 4); \ 203 break; \ 204 case 8: \ 205 if (sizeof((x)) < 8) \ 206 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 207 else \ 208 __get_user_x(__r2, __p, __e, __l, 8); \ 209 break; \ 210 default: __e = __get_user_bad(); break; \ 211 } \ 212 uaccess_restore(__ua_flags); \ 213 x = (typeof(*(p))) __r2; \ 214 __e; \ 215 }) 216 217 #define get_user(x, p) \ 218 ({ \ 219 might_fault(); \ 220 __get_user_check(x, p); \ 221 }) 222 223 extern int __put_user_1(void *, unsigned int); 224 extern int __put_user_2(void *, unsigned int); 225 extern int __put_user_4(void *, unsigned int); 226 extern int __put_user_8(void *, unsigned long long); 227 228 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 229 ({ \ 230 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 231 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 232 register const void __user *__p asm("r0") = __ptr; \ 233 register unsigned long __l asm("r1") = __limit; \ 234 register int __e asm("r0"); \ 235 __asm__ __volatile__ ( \ 236 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 237 __asmeq("%3", "r1") \ 238 "bl __put_user_" #__s \ 239 : "=&r" (__e) \ 240 : "0" (__p), "r" (__r2), "r" (__l) \ 241 : "ip", "lr", "cc"); \ 242 __err = __e; \ 243 }) 244 245 #else /* CONFIG_MMU */ 246 247 /* 248 * uClinux has only one addr space, so has simplified address limits. 249 */ 250 #define USER_DS KERNEL_DS 251 252 #define segment_eq(a, b) (1) 253 #define __addr_ok(addr) ((void)(addr), 1) 254 #define __range_ok(addr, size) ((void)(addr), 0) 255 #define get_fs() (KERNEL_DS) 256 257 static inline void set_fs(mm_segment_t fs) 258 { 259 } 260 261 #define get_user(x, p) __get_user(x, p) 262 #define __put_user_check __put_user_nocheck 263 264 #endif /* CONFIG_MMU */ 265 266 #define access_ok(type, addr, size) (__range_ok(addr, size) == 0) 267 268 #define user_addr_max() \ 269 (uaccess_kernel() ? ~0UL : get_fs()) 270 271 /* 272 * The "__xxx" versions of the user access functions do not verify the 273 * address space - it must have been done previously with a separate 274 * "access_ok()" call. 275 * 276 * The "xxx_error" versions set the third argument to EFAULT if an 277 * error occurs, and leave it unchanged on success. Note that these 278 * versions are void (ie, don't return a value as such). 279 */ 280 #define __get_user(x, ptr) \ 281 ({ \ 282 long __gu_err = 0; \ 283 __get_user_err((x), (ptr), __gu_err); \ 284 __gu_err; \ 285 }) 286 287 #define __get_user_error(x, ptr, err) \ 288 ({ \ 289 __get_user_err((x), (ptr), err); \ 290 (void) 0; \ 291 }) 292 293 #define __get_user_err(x, ptr, err) \ 294 do { \ 295 unsigned long __gu_addr = (unsigned long)(ptr); \ 296 unsigned long __gu_val; \ 297 unsigned int __ua_flags; \ 298 __chk_user_ptr(ptr); \ 299 might_fault(); \ 300 __ua_flags = uaccess_save_and_enable(); \ 301 switch (sizeof(*(ptr))) { \ 302 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \ 303 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \ 304 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \ 305 default: (__gu_val) = __get_user_bad(); \ 306 } \ 307 uaccess_restore(__ua_flags); \ 308 (x) = (__typeof__(*(ptr)))__gu_val; \ 309 } while (0) 310 311 #define __get_user_asm(x, addr, err, instr) \ 312 __asm__ __volatile__( \ 313 "1: " TUSER(instr) " %1, [%2], #0\n" \ 314 "2:\n" \ 315 " .pushsection .text.fixup,\"ax\"\n" \ 316 " .align 2\n" \ 317 "3: mov %0, %3\n" \ 318 " mov %1, #0\n" \ 319 " b 2b\n" \ 320 " .popsection\n" \ 321 " .pushsection __ex_table,\"a\"\n" \ 322 " .align 3\n" \ 323 " .long 1b, 3b\n" \ 324 " .popsection" \ 325 : "+r" (err), "=&r" (x) \ 326 : "r" (addr), "i" (-EFAULT) \ 327 : "cc") 328 329 #define __get_user_asm_byte(x, addr, err) \ 330 __get_user_asm(x, addr, err, ldrb) 331 332 #ifndef __ARMEB__ 333 #define __get_user_asm_half(x, __gu_addr, err) \ 334 ({ \ 335 unsigned long __b1, __b2; \ 336 __get_user_asm_byte(__b1, __gu_addr, err); \ 337 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 338 (x) = __b1 | (__b2 << 8); \ 339 }) 340 #else 341 #define __get_user_asm_half(x, __gu_addr, err) \ 342 ({ \ 343 unsigned long __b1, __b2; \ 344 __get_user_asm_byte(__b1, __gu_addr, err); \ 345 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 346 (x) = (__b1 << 8) | __b2; \ 347 }) 348 #endif 349 350 #define __get_user_asm_word(x, addr, err) \ 351 __get_user_asm(x, addr, err, ldr) 352 353 354 #define __put_user_switch(x, ptr, __err, __fn) \ 355 do { \ 356 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 357 __typeof__(*(ptr)) __pu_val = (x); \ 358 unsigned int __ua_flags; \ 359 might_fault(); \ 360 __ua_flags = uaccess_save_and_enable(); \ 361 switch (sizeof(*(ptr))) { \ 362 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 363 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 364 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 365 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 366 default: __err = __put_user_bad(); break; \ 367 } \ 368 uaccess_restore(__ua_flags); \ 369 } while (0) 370 371 #define put_user(x, ptr) \ 372 ({ \ 373 int __pu_err = 0; \ 374 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 375 __pu_err; \ 376 }) 377 378 #define __put_user(x, ptr) \ 379 ({ \ 380 long __pu_err = 0; \ 381 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 382 __pu_err; \ 383 }) 384 385 #define __put_user_error(x, ptr, err) \ 386 ({ \ 387 __put_user_switch((x), (ptr), (err), __put_user_nocheck); \ 388 (void) 0; \ 389 }) 390 391 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 392 do { \ 393 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 394 __put_user_nocheck_##__size(x, __pu_addr, __err); \ 395 } while (0) 396 397 #define __put_user_nocheck_1 __put_user_asm_byte 398 #define __put_user_nocheck_2 __put_user_asm_half 399 #define __put_user_nocheck_4 __put_user_asm_word 400 #define __put_user_nocheck_8 __put_user_asm_dword 401 402 #define __put_user_asm(x, __pu_addr, err, instr) \ 403 __asm__ __volatile__( \ 404 "1: " TUSER(instr) " %1, [%2], #0\n" \ 405 "2:\n" \ 406 " .pushsection .text.fixup,\"ax\"\n" \ 407 " .align 2\n" \ 408 "3: mov %0, %3\n" \ 409 " b 2b\n" \ 410 " .popsection\n" \ 411 " .pushsection __ex_table,\"a\"\n" \ 412 " .align 3\n" \ 413 " .long 1b, 3b\n" \ 414 " .popsection" \ 415 : "+r" (err) \ 416 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 417 : "cc") 418 419 #define __put_user_asm_byte(x, __pu_addr, err) \ 420 __put_user_asm(x, __pu_addr, err, strb) 421 422 #ifndef __ARMEB__ 423 #define __put_user_asm_half(x, __pu_addr, err) \ 424 ({ \ 425 unsigned long __temp = (__force unsigned long)(x); \ 426 __put_user_asm_byte(__temp, __pu_addr, err); \ 427 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \ 428 }) 429 #else 430 #define __put_user_asm_half(x, __pu_addr, err) \ 431 ({ \ 432 unsigned long __temp = (__force unsigned long)(x); \ 433 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \ 434 __put_user_asm_byte(__temp, __pu_addr + 1, err); \ 435 }) 436 #endif 437 438 #define __put_user_asm_word(x, __pu_addr, err) \ 439 __put_user_asm(x, __pu_addr, err, str) 440 441 #ifndef __ARMEB__ 442 #define __reg_oper0 "%R2" 443 #define __reg_oper1 "%Q2" 444 #else 445 #define __reg_oper0 "%Q2" 446 #define __reg_oper1 "%R2" 447 #endif 448 449 #define __put_user_asm_dword(x, __pu_addr, err) \ 450 __asm__ __volatile__( \ 451 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \ 452 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \ 453 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \ 454 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \ 455 "3:\n" \ 456 " .pushsection .text.fixup,\"ax\"\n" \ 457 " .align 2\n" \ 458 "4: mov %0, %3\n" \ 459 " b 3b\n" \ 460 " .popsection\n" \ 461 " .pushsection __ex_table,\"a\"\n" \ 462 " .align 3\n" \ 463 " .long 1b, 4b\n" \ 464 " .long 2b, 4b\n" \ 465 " .popsection" \ 466 : "+r" (err), "+r" (__pu_addr) \ 467 : "r" (x), "i" (-EFAULT) \ 468 : "cc") 469 470 471 #ifdef CONFIG_MMU 472 extern unsigned long __must_check 473 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 474 475 static inline unsigned long __must_check 476 __arch_copy_from_user(void *to, const void __user *from, unsigned long n) 477 { 478 unsigned int __ua_flags; 479 480 __ua_flags = uaccess_save_and_enable(); 481 n = arm_copy_from_user(to, from, n); 482 uaccess_restore(__ua_flags); 483 return n; 484 } 485 486 extern unsigned long __must_check 487 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 488 extern unsigned long __must_check 489 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 490 491 static inline unsigned long __must_check 492 __arch_copy_to_user(void __user *to, const void *from, unsigned long n) 493 { 494 #ifndef CONFIG_UACCESS_WITH_MEMCPY 495 unsigned int __ua_flags; 496 __ua_flags = uaccess_save_and_enable(); 497 n = arm_copy_to_user(to, from, n); 498 uaccess_restore(__ua_flags); 499 return n; 500 #else 501 return arm_copy_to_user(to, from, n); 502 #endif 503 } 504 505 extern unsigned long __must_check 506 arm_clear_user(void __user *addr, unsigned long n); 507 extern unsigned long __must_check 508 __clear_user_std(void __user *addr, unsigned long n); 509 510 static inline unsigned long __must_check 511 __clear_user(void __user *addr, unsigned long n) 512 { 513 unsigned int __ua_flags = uaccess_save_and_enable(); 514 n = arm_clear_user(addr, n); 515 uaccess_restore(__ua_flags); 516 return n; 517 } 518 519 #else 520 #define __arch_copy_from_user(to, from, n) \ 521 (memcpy(to, (void __force *)from, n), 0) 522 #define __arch_copy_to_user(to, from, n) \ 523 (memcpy((void __force *)to, from, n), 0) 524 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 525 #endif 526 527 static inline unsigned long __must_check 528 __copy_from_user(void *to, const void __user *from, unsigned long n) 529 { 530 check_object_size(to, n, false); 531 return __arch_copy_from_user(to, from, n); 532 } 533 534 static inline unsigned long __must_check 535 copy_from_user(void *to, const void __user *from, unsigned long n) 536 { 537 unsigned long res = n; 538 539 check_object_size(to, n, false); 540 541 if (likely(access_ok(VERIFY_READ, from, n))) 542 res = __arch_copy_from_user(to, from, n); 543 if (unlikely(res)) 544 memset(to + (n - res), 0, res); 545 return res; 546 } 547 548 static inline unsigned long __must_check 549 __copy_to_user(void __user *to, const void *from, unsigned long n) 550 { 551 check_object_size(from, n, true); 552 553 return __arch_copy_to_user(to, from, n); 554 } 555 556 static inline unsigned long __must_check 557 copy_to_user(void __user *to, const void *from, unsigned long n) 558 { 559 check_object_size(from, n, true); 560 561 if (access_ok(VERIFY_WRITE, to, n)) 562 n = __arch_copy_to_user(to, from, n); 563 return n; 564 } 565 566 #define __copy_to_user_inatomic __copy_to_user 567 #define __copy_from_user_inatomic __copy_from_user 568 569 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 570 { 571 if (access_ok(VERIFY_WRITE, to, n)) 572 n = __clear_user(to, n); 573 return n; 574 } 575 576 /* These are from lib/ code, and use __get_user() and friends */ 577 extern long strncpy_from_user(char *dest, const char __user *src, long count); 578 579 extern __must_check long strlen_user(const char __user *str); 580 extern __must_check long strnlen_user(const char __user *str, long n); 581 582 #endif /* _ASMARM_UACCESS_H */ 583