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 45struct exception_table_entry 46{ 47 unsigned long insn, fixup; 48}; 49 50extern 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 */ 58static 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 73static 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 */ 85extern int __get_user_bad(void); 86extern 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 99static 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#define __addr_ok(addr) ({ \ 108 unsigned long flag; \ 109 __asm__("cmp %2, %0; movlo %0, #0" \ 110 : "=&r" (flag) \ 111 : "0" (current_thread_info()->addr_limit), "r" (addr) \ 112 : "cc"); \ 113 (flag == 0); }) 114 115/* We use 33-bit arithmetic here... */ 116#define __range_ok(addr, size) ({ \ 117 unsigned long flag, roksum; \ 118 __chk_user_ptr(addr); \ 119 __asm__("adds %1, %2, %3; sbcccs %1, %1, %0; movcc %0, #0" \ 120 : "=&r" (flag), "=&r" (roksum) \ 121 : "r" (addr), "Ir" (size), "0" (current_thread_info()->addr_limit) \ 122 : "cc"); \ 123 flag; }) 124 125/* 126 * Single-value transfer routines. They automatically use the right 127 * size if we just have the right pointer type. Note that the functions 128 * which read from user space (*get_*) need to take care not to leak 129 * kernel data even if the calling code is buggy and fails to check 130 * the return value. This means zeroing out the destination variable 131 * or buffer on error. Normally this is done out of line by the 132 * fixup code, but there are a few places where it intrudes on the 133 * main code path. When we only write to user space, there is no 134 * problem. 135 */ 136extern int __get_user_1(void *); 137extern int __get_user_2(void *); 138extern int __get_user_4(void *); 139extern int __get_user_32t_8(void *); 140extern int __get_user_8(void *); 141extern int __get_user_64t_1(void *); 142extern int __get_user_64t_2(void *); 143extern int __get_user_64t_4(void *); 144 145#define __GUP_CLOBBER_1 "lr", "cc" 146#ifdef CONFIG_CPU_USE_DOMAINS 147#define __GUP_CLOBBER_2 "ip", "lr", "cc" 148#else 149#define __GUP_CLOBBER_2 "lr", "cc" 150#endif 151#define __GUP_CLOBBER_4 "lr", "cc" 152#define __GUP_CLOBBER_32t_8 "lr", "cc" 153#define __GUP_CLOBBER_8 "lr", "cc" 154 155#define __get_user_x(__r2, __p, __e, __l, __s) \ 156 __asm__ __volatile__ ( \ 157 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 158 __asmeq("%3", "r1") \ 159 "bl __get_user_" #__s \ 160 : "=&r" (__e), "=r" (__r2) \ 161 : "0" (__p), "r" (__l) \ 162 : __GUP_CLOBBER_##__s) 163 164/* narrowing a double-word get into a single 32bit word register: */ 165#ifdef __ARMEB__ 166#define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 167 __get_user_x(__r2, __p, __e, __l, 32t_8) 168#else 169#define __get_user_x_32t __get_user_x 170#endif 171 172/* 173 * storing result into proper least significant word of 64bit target var, 174 * different only for big endian case where 64 bit __r2 lsw is r3: 175 */ 176#ifdef __ARMEB__ 177#define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 178 __asm__ __volatile__ ( \ 179 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 180 __asmeq("%3", "r1") \ 181 "bl __get_user_64t_" #__s \ 182 : "=&r" (__e), "=r" (__r2) \ 183 : "0" (__p), "r" (__l) \ 184 : __GUP_CLOBBER_##__s) 185#else 186#define __get_user_x_64t __get_user_x 187#endif 188 189 190#define __get_user_check(x, p) \ 191 ({ \ 192 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 193 register const typeof(*(p)) __user *__p asm("r0") = (p);\ 194 register typeof(x) __r2 asm("r2"); \ 195 register unsigned long __l asm("r1") = __limit; \ 196 register int __e asm("r0"); \ 197 unsigned int __ua_flags = uaccess_save_and_enable(); \ 198 switch (sizeof(*(__p))) { \ 199 case 1: \ 200 if (sizeof((x)) >= 8) \ 201 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 202 else \ 203 __get_user_x(__r2, __p, __e, __l, 1); \ 204 break; \ 205 case 2: \ 206 if (sizeof((x)) >= 8) \ 207 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 208 else \ 209 __get_user_x(__r2, __p, __e, __l, 2); \ 210 break; \ 211 case 4: \ 212 if (sizeof((x)) >= 8) \ 213 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 214 else \ 215 __get_user_x(__r2, __p, __e, __l, 4); \ 216 break; \ 217 case 8: \ 218 if (sizeof((x)) < 8) \ 219 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 220 else \ 221 __get_user_x(__r2, __p, __e, __l, 8); \ 222 break; \ 223 default: __e = __get_user_bad(); break; \ 224 } \ 225 uaccess_restore(__ua_flags); \ 226 x = (typeof(*(p))) __r2; \ 227 __e; \ 228 }) 229 230#define get_user(x, p) \ 231 ({ \ 232 might_fault(); \ 233 __get_user_check(x, p); \ 234 }) 235 236extern int __put_user_1(void *, unsigned int); 237extern int __put_user_2(void *, unsigned int); 238extern int __put_user_4(void *, unsigned int); 239extern int __put_user_8(void *, unsigned long long); 240 241#define __put_user_x(__r2, __p, __e, __l, __s) \ 242 __asm__ __volatile__ ( \ 243 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 244 __asmeq("%3", "r1") \ 245 "bl __put_user_" #__s \ 246 : "=&r" (__e) \ 247 : "0" (__p), "r" (__r2), "r" (__l) \ 248 : "ip", "lr", "cc") 249 250#define __put_user_check(x, p) \ 251 ({ \ 252 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 253 const typeof(*(p)) __user *__tmp_p = (p); \ 254 register const typeof(*(p)) __r2 asm("r2") = (x); \ 255 register const typeof(*(p)) __user *__p asm("r0") = __tmp_p; \ 256 register unsigned long __l asm("r1") = __limit; \ 257 register int __e asm("r0"); \ 258 unsigned int __ua_flags = uaccess_save_and_enable(); \ 259 switch (sizeof(*(__p))) { \ 260 case 1: \ 261 __put_user_x(__r2, __p, __e, __l, 1); \ 262 break; \ 263 case 2: \ 264 __put_user_x(__r2, __p, __e, __l, 2); \ 265 break; \ 266 case 4: \ 267 __put_user_x(__r2, __p, __e, __l, 4); \ 268 break; \ 269 case 8: \ 270 __put_user_x(__r2, __p, __e, __l, 8); \ 271 break; \ 272 default: __e = __put_user_bad(); break; \ 273 } \ 274 uaccess_restore(__ua_flags); \ 275 __e; \ 276 }) 277 278#define put_user(x, p) \ 279 ({ \ 280 might_fault(); \ 281 __put_user_check(x, p); \ 282 }) 283 284#else /* CONFIG_MMU */ 285 286/* 287 * uClinux has only one addr space, so has simplified address limits. 288 */ 289#define USER_DS KERNEL_DS 290 291#define segment_eq(a, b) (1) 292#define __addr_ok(addr) ((void)(addr), 1) 293#define __range_ok(addr, size) ((void)(addr), 0) 294#define get_fs() (KERNEL_DS) 295 296static inline void set_fs(mm_segment_t fs) 297{ 298} 299 300#define get_user(x, p) __get_user(x, p) 301#define put_user(x, p) __put_user(x, p) 302 303#endif /* CONFIG_MMU */ 304 305#define access_ok(type, addr, size) (__range_ok(addr, size) == 0) 306 307#define user_addr_max() \ 308 (segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs()) 309 310/* 311 * The "__xxx" versions of the user access functions do not verify the 312 * address space - it must have been done previously with a separate 313 * "access_ok()" call. 314 * 315 * The "xxx_error" versions set the third argument to EFAULT if an 316 * error occurs, and leave it unchanged on success. Note that these 317 * versions are void (ie, don't return a value as such). 318 */ 319#define __get_user(x, ptr) \ 320({ \ 321 long __gu_err = 0; \ 322 __get_user_err((x), (ptr), __gu_err); \ 323 __gu_err; \ 324}) 325 326#define __get_user_error(x, ptr, err) \ 327({ \ 328 __get_user_err((x), (ptr), err); \ 329 (void) 0; \ 330}) 331 332#define __get_user_err(x, ptr, err) \ 333do { \ 334 unsigned long __gu_addr = (unsigned long)(ptr); \ 335 unsigned long __gu_val; \ 336 unsigned int __ua_flags; \ 337 __chk_user_ptr(ptr); \ 338 might_fault(); \ 339 __ua_flags = uaccess_save_and_enable(); \ 340 switch (sizeof(*(ptr))) { \ 341 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \ 342 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \ 343 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \ 344 default: (__gu_val) = __get_user_bad(); \ 345 } \ 346 uaccess_restore(__ua_flags); \ 347 (x) = (__typeof__(*(ptr)))__gu_val; \ 348} while (0) 349 350#define __get_user_asm(x, addr, err, instr) \ 351 __asm__ __volatile__( \ 352 "1: " TUSER(instr) " %1, [%2], #0\n" \ 353 "2:\n" \ 354 " .pushsection .text.fixup,\"ax\"\n" \ 355 " .align 2\n" \ 356 "3: mov %0, %3\n" \ 357 " mov %1, #0\n" \ 358 " b 2b\n" \ 359 " .popsection\n" \ 360 " .pushsection __ex_table,\"a\"\n" \ 361 " .align 3\n" \ 362 " .long 1b, 3b\n" \ 363 " .popsection" \ 364 : "+r" (err), "=&r" (x) \ 365 : "r" (addr), "i" (-EFAULT) \ 366 : "cc") 367 368#define __get_user_asm_byte(x, addr, err) \ 369 __get_user_asm(x, addr, err, ldrb) 370 371#ifndef __ARMEB__ 372#define __get_user_asm_half(x, __gu_addr, err) \ 373({ \ 374 unsigned long __b1, __b2; \ 375 __get_user_asm_byte(__b1, __gu_addr, err); \ 376 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 377 (x) = __b1 | (__b2 << 8); \ 378}) 379#else 380#define __get_user_asm_half(x, __gu_addr, err) \ 381({ \ 382 unsigned long __b1, __b2; \ 383 __get_user_asm_byte(__b1, __gu_addr, err); \ 384 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 385 (x) = (__b1 << 8) | __b2; \ 386}) 387#endif 388 389#define __get_user_asm_word(x, addr, err) \ 390 __get_user_asm(x, addr, err, ldr) 391 392#define __put_user(x, ptr) \ 393({ \ 394 long __pu_err = 0; \ 395 __put_user_err((x), (ptr), __pu_err); \ 396 __pu_err; \ 397}) 398 399#define __put_user_error(x, ptr, err) \ 400({ \ 401 __put_user_err((x), (ptr), err); \ 402 (void) 0; \ 403}) 404 405#define __put_user_err(x, ptr, err) \ 406do { \ 407 unsigned long __pu_addr = (unsigned long)(ptr); \ 408 unsigned int __ua_flags; \ 409 __typeof__(*(ptr)) __pu_val = (x); \ 410 __chk_user_ptr(ptr); \ 411 might_fault(); \ 412 __ua_flags = uaccess_save_and_enable(); \ 413 switch (sizeof(*(ptr))) { \ 414 case 1: __put_user_asm_byte(__pu_val, __pu_addr, err); break; \ 415 case 2: __put_user_asm_half(__pu_val, __pu_addr, err); break; \ 416 case 4: __put_user_asm_word(__pu_val, __pu_addr, err); break; \ 417 case 8: __put_user_asm_dword(__pu_val, __pu_addr, err); break; \ 418 default: __put_user_bad(); \ 419 } \ 420 uaccess_restore(__ua_flags); \ 421} while (0) 422 423#define __put_user_asm(x, __pu_addr, err, instr) \ 424 __asm__ __volatile__( \ 425 "1: " TUSER(instr) " %1, [%2], #0\n" \ 426 "2:\n" \ 427 " .pushsection .text.fixup,\"ax\"\n" \ 428 " .align 2\n" \ 429 "3: mov %0, %3\n" \ 430 " b 2b\n" \ 431 " .popsection\n" \ 432 " .pushsection __ex_table,\"a\"\n" \ 433 " .align 3\n" \ 434 " .long 1b, 3b\n" \ 435 " .popsection" \ 436 : "+r" (err) \ 437 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 438 : "cc") 439 440#define __put_user_asm_byte(x, __pu_addr, err) \ 441 __put_user_asm(x, __pu_addr, err, strb) 442 443#ifndef __ARMEB__ 444#define __put_user_asm_half(x, __pu_addr, err) \ 445({ \ 446 unsigned long __temp = (__force unsigned long)(x); \ 447 __put_user_asm_byte(__temp, __pu_addr, err); \ 448 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \ 449}) 450#else 451#define __put_user_asm_half(x, __pu_addr, err) \ 452({ \ 453 unsigned long __temp = (__force unsigned long)(x); \ 454 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \ 455 __put_user_asm_byte(__temp, __pu_addr + 1, err); \ 456}) 457#endif 458 459#define __put_user_asm_word(x, __pu_addr, err) \ 460 __put_user_asm(x, __pu_addr, err, str) 461 462#ifndef __ARMEB__ 463#define __reg_oper0 "%R2" 464#define __reg_oper1 "%Q2" 465#else 466#define __reg_oper0 "%Q2" 467#define __reg_oper1 "%R2" 468#endif 469 470#define __put_user_asm_dword(x, __pu_addr, err) \ 471 __asm__ __volatile__( \ 472 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \ 473 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \ 474 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \ 475 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \ 476 "3:\n" \ 477 " .pushsection .text.fixup,\"ax\"\n" \ 478 " .align 2\n" \ 479 "4: mov %0, %3\n" \ 480 " b 3b\n" \ 481 " .popsection\n" \ 482 " .pushsection __ex_table,\"a\"\n" \ 483 " .align 3\n" \ 484 " .long 1b, 4b\n" \ 485 " .long 2b, 4b\n" \ 486 " .popsection" \ 487 : "+r" (err), "+r" (__pu_addr) \ 488 : "r" (x), "i" (-EFAULT) \ 489 : "cc") 490 491 492#ifdef CONFIG_MMU 493extern unsigned long __must_check 494arm_copy_from_user(void *to, const void __user *from, unsigned long n); 495 496static inline unsigned long __must_check 497__copy_from_user(void *to, const void __user *from, unsigned long n) 498{ 499 unsigned int __ua_flags = uaccess_save_and_enable(); 500 n = arm_copy_from_user(to, from, n); 501 uaccess_restore(__ua_flags); 502 return n; 503} 504 505extern unsigned long __must_check 506arm_copy_to_user(void __user *to, const void *from, unsigned long n); 507extern unsigned long __must_check 508__copy_to_user_std(void __user *to, const void *from, unsigned long n); 509 510static inline unsigned long __must_check 511__copy_to_user(void __user *to, const void *from, unsigned long n) 512{ 513#ifndef CONFIG_UACCESS_WITH_MEMCPY 514 unsigned int __ua_flags = uaccess_save_and_enable(); 515 n = arm_copy_to_user(to, from, n); 516 uaccess_restore(__ua_flags); 517 return n; 518#else 519 return arm_copy_to_user(to, from, n); 520#endif 521} 522 523extern unsigned long __must_check 524arm_clear_user(void __user *addr, unsigned long n); 525extern unsigned long __must_check 526__clear_user_std(void __user *addr, unsigned long n); 527 528static inline unsigned long __must_check 529__clear_user(void __user *addr, unsigned long n) 530{ 531 unsigned int __ua_flags = uaccess_save_and_enable(); 532 n = arm_clear_user(addr, n); 533 uaccess_restore(__ua_flags); 534 return n; 535} 536 537#else 538#define __copy_from_user(to, from, n) (memcpy(to, (void __force *)from, n), 0) 539#define __copy_to_user(to, from, n) (memcpy((void __force *)to, from, n), 0) 540#define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 541#endif 542 543static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) 544{ 545 if (access_ok(VERIFY_READ, from, n)) 546 n = __copy_from_user(to, from, n); 547 else /* security hole - plug it */ 548 memset(to, 0, n); 549 return n; 550} 551 552static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) 553{ 554 if (access_ok(VERIFY_WRITE, to, n)) 555 n = __copy_to_user(to, from, n); 556 return n; 557} 558 559#define __copy_to_user_inatomic __copy_to_user 560#define __copy_from_user_inatomic __copy_from_user 561 562static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 563{ 564 if (access_ok(VERIFY_WRITE, to, n)) 565 n = __clear_user(to, n); 566 return n; 567} 568 569/* These are from lib/ code, and use __get_user() and friends */ 570extern long strncpy_from_user(char *dest, const char __user *src, long count); 571 572extern __must_check long strlen_user(const char __user *str); 573extern __must_check long strnlen_user(const char __user *str, long n); 574 575#endif /* _ASMARM_UACCESS_H */ 576