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