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 * Single-value transfer routines. They automatically use the right 89 * size if we just have the right pointer type. Note that the functions 90 * which read from user space (*get_*) need to take care not to leak 91 * kernel data even if the calling code is buggy and fails to check 92 * the return value. This means zeroing out the destination variable 93 * or buffer on error. Normally this is done out of line by the 94 * fixup code, but there are a few places where it intrudes on the 95 * main code path. When we only write to user space, there is no 96 * problem. 97 */ 98 extern int __get_user_1(void *); 99 extern int __get_user_2(void *); 100 extern int __get_user_4(void *); 101 extern int __get_user_32t_8(void *); 102 extern int __get_user_8(void *); 103 extern int __get_user_64t_1(void *); 104 extern int __get_user_64t_2(void *); 105 extern int __get_user_64t_4(void *); 106 107 #define __GUP_CLOBBER_1 "lr", "cc" 108 #ifdef CONFIG_CPU_USE_DOMAINS 109 #define __GUP_CLOBBER_2 "ip", "lr", "cc" 110 #else 111 #define __GUP_CLOBBER_2 "lr", "cc" 112 #endif 113 #define __GUP_CLOBBER_4 "lr", "cc" 114 #define __GUP_CLOBBER_32t_8 "lr", "cc" 115 #define __GUP_CLOBBER_8 "lr", "cc" 116 117 #define __get_user_x(__r2, __p, __e, __l, __s) \ 118 __asm__ __volatile__ ( \ 119 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 120 __asmeq("%3", "r1") \ 121 "bl __get_user_" #__s \ 122 : "=&r" (__e), "=r" (__r2) \ 123 : "0" (__p), "r" (__l) \ 124 : __GUP_CLOBBER_##__s) 125 126 /* narrowing a double-word get into a single 32bit word register: */ 127 #ifdef __ARMEB__ 128 #define __get_user_x_32t(__r2, __p, __e, __l, __s) \ 129 __get_user_x(__r2, __p, __e, __l, 32t_8) 130 #else 131 #define __get_user_x_32t __get_user_x 132 #endif 133 134 /* 135 * storing result into proper least significant word of 64bit target var, 136 * different only for big endian case where 64 bit __r2 lsw is r3: 137 */ 138 #ifdef __ARMEB__ 139 #define __get_user_x_64t(__r2, __p, __e, __l, __s) \ 140 __asm__ __volatile__ ( \ 141 __asmeq("%0", "r0") __asmeq("%1", "r2") \ 142 __asmeq("%3", "r1") \ 143 "bl __get_user_64t_" #__s \ 144 : "=&r" (__e), "=r" (__r2) \ 145 : "0" (__p), "r" (__l) \ 146 : __GUP_CLOBBER_##__s) 147 #else 148 #define __get_user_x_64t __get_user_x 149 #endif 150 151 152 #define __get_user_check(x, p) \ 153 ({ \ 154 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 155 register const typeof(*(p)) __user *__p asm("r0") = (p);\ 156 register typeof(x) __r2 asm("r2"); \ 157 register unsigned long __l asm("r1") = __limit; \ 158 register int __e asm("r0"); \ 159 unsigned int __ua_flags = uaccess_save_and_enable(); \ 160 switch (sizeof(*(__p))) { \ 161 case 1: \ 162 if (sizeof((x)) >= 8) \ 163 __get_user_x_64t(__r2, __p, __e, __l, 1); \ 164 else \ 165 __get_user_x(__r2, __p, __e, __l, 1); \ 166 break; \ 167 case 2: \ 168 if (sizeof((x)) >= 8) \ 169 __get_user_x_64t(__r2, __p, __e, __l, 2); \ 170 else \ 171 __get_user_x(__r2, __p, __e, __l, 2); \ 172 break; \ 173 case 4: \ 174 if (sizeof((x)) >= 8) \ 175 __get_user_x_64t(__r2, __p, __e, __l, 4); \ 176 else \ 177 __get_user_x(__r2, __p, __e, __l, 4); \ 178 break; \ 179 case 8: \ 180 if (sizeof((x)) < 8) \ 181 __get_user_x_32t(__r2, __p, __e, __l, 4); \ 182 else \ 183 __get_user_x(__r2, __p, __e, __l, 8); \ 184 break; \ 185 default: __e = __get_user_bad(); break; \ 186 } \ 187 uaccess_restore(__ua_flags); \ 188 x = (typeof(*(p))) __r2; \ 189 __e; \ 190 }) 191 192 #define get_user(x, p) \ 193 ({ \ 194 might_fault(); \ 195 __get_user_check(x, p); \ 196 }) 197 198 extern int __put_user_1(void *, unsigned int); 199 extern int __put_user_2(void *, unsigned int); 200 extern int __put_user_4(void *, unsigned int); 201 extern int __put_user_8(void *, unsigned long long); 202 203 #define __put_user_check(__pu_val, __ptr, __err, __s) \ 204 ({ \ 205 unsigned long __limit = current_thread_info()->addr_limit - 1; \ 206 register typeof(__pu_val) __r2 asm("r2") = __pu_val; \ 207 register const void __user *__p asm("r0") = __ptr; \ 208 register unsigned long __l asm("r1") = __limit; \ 209 register int __e asm("r0"); \ 210 __asm__ __volatile__ ( \ 211 __asmeq("%0", "r0") __asmeq("%2", "r2") \ 212 __asmeq("%3", "r1") \ 213 "bl __put_user_" #__s \ 214 : "=&r" (__e) \ 215 : "0" (__p), "r" (__r2), "r" (__l) \ 216 : "ip", "lr", "cc"); \ 217 __err = __e; \ 218 }) 219 220 #else /* CONFIG_MMU */ 221 222 /* 223 * uClinux has only one addr space, so has simplified address limits. 224 */ 225 #define USER_DS KERNEL_DS 226 227 #define segment_eq(a, b) (1) 228 #define __addr_ok(addr) ((void)(addr), 1) 229 #define __range_ok(addr, size) ((void)(addr), 0) 230 #define get_fs() (KERNEL_DS) 231 232 static inline void set_fs(mm_segment_t fs) 233 { 234 } 235 236 #define get_user(x, p) __get_user(x, p) 237 #define __put_user_check __put_user_nocheck 238 239 #endif /* CONFIG_MMU */ 240 241 #define access_ok(type, addr, size) (__range_ok(addr, size) == 0) 242 243 #define user_addr_max() \ 244 (uaccess_kernel() ? ~0UL : get_fs()) 245 246 /* 247 * The "__xxx" versions of the user access functions do not verify the 248 * address space - it must have been done previously with a separate 249 * "access_ok()" call. 250 * 251 * The "xxx_error" versions set the third argument to EFAULT if an 252 * error occurs, and leave it unchanged on success. Note that these 253 * versions are void (ie, don't return a value as such). 254 */ 255 #define __get_user(x, ptr) \ 256 ({ \ 257 long __gu_err = 0; \ 258 __get_user_err((x), (ptr), __gu_err); \ 259 __gu_err; \ 260 }) 261 262 #define __get_user_error(x, ptr, err) \ 263 ({ \ 264 __get_user_err((x), (ptr), err); \ 265 (void) 0; \ 266 }) 267 268 #define __get_user_err(x, ptr, err) \ 269 do { \ 270 unsigned long __gu_addr = (unsigned long)(ptr); \ 271 unsigned long __gu_val; \ 272 unsigned int __ua_flags; \ 273 __chk_user_ptr(ptr); \ 274 might_fault(); \ 275 __ua_flags = uaccess_save_and_enable(); \ 276 switch (sizeof(*(ptr))) { \ 277 case 1: __get_user_asm_byte(__gu_val, __gu_addr, err); break; \ 278 case 2: __get_user_asm_half(__gu_val, __gu_addr, err); break; \ 279 case 4: __get_user_asm_word(__gu_val, __gu_addr, err); break; \ 280 default: (__gu_val) = __get_user_bad(); \ 281 } \ 282 uaccess_restore(__ua_flags); \ 283 (x) = (__typeof__(*(ptr)))__gu_val; \ 284 } while (0) 285 286 #define __get_user_asm(x, addr, err, instr) \ 287 __asm__ __volatile__( \ 288 "1: " TUSER(instr) " %1, [%2], #0\n" \ 289 "2:\n" \ 290 " .pushsection .text.fixup,\"ax\"\n" \ 291 " .align 2\n" \ 292 "3: mov %0, %3\n" \ 293 " mov %1, #0\n" \ 294 " b 2b\n" \ 295 " .popsection\n" \ 296 " .pushsection __ex_table,\"a\"\n" \ 297 " .align 3\n" \ 298 " .long 1b, 3b\n" \ 299 " .popsection" \ 300 : "+r" (err), "=&r" (x) \ 301 : "r" (addr), "i" (-EFAULT) \ 302 : "cc") 303 304 #define __get_user_asm_byte(x, addr, err) \ 305 __get_user_asm(x, addr, err, ldrb) 306 307 #ifndef __ARMEB__ 308 #define __get_user_asm_half(x, __gu_addr, err) \ 309 ({ \ 310 unsigned long __b1, __b2; \ 311 __get_user_asm_byte(__b1, __gu_addr, err); \ 312 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 313 (x) = __b1 | (__b2 << 8); \ 314 }) 315 #else 316 #define __get_user_asm_half(x, __gu_addr, err) \ 317 ({ \ 318 unsigned long __b1, __b2; \ 319 __get_user_asm_byte(__b1, __gu_addr, err); \ 320 __get_user_asm_byte(__b2, __gu_addr + 1, err); \ 321 (x) = (__b1 << 8) | __b2; \ 322 }) 323 #endif 324 325 #define __get_user_asm_word(x, addr, err) \ 326 __get_user_asm(x, addr, err, ldr) 327 328 329 #define __put_user_switch(x, ptr, __err, __fn) \ 330 do { \ 331 const __typeof__(*(ptr)) __user *__pu_ptr = (ptr); \ 332 __typeof__(*(ptr)) __pu_val = (x); \ 333 unsigned int __ua_flags; \ 334 might_fault(); \ 335 __ua_flags = uaccess_save_and_enable(); \ 336 switch (sizeof(*(ptr))) { \ 337 case 1: __fn(__pu_val, __pu_ptr, __err, 1); break; \ 338 case 2: __fn(__pu_val, __pu_ptr, __err, 2); break; \ 339 case 4: __fn(__pu_val, __pu_ptr, __err, 4); break; \ 340 case 8: __fn(__pu_val, __pu_ptr, __err, 8); break; \ 341 default: __err = __put_user_bad(); break; \ 342 } \ 343 uaccess_restore(__ua_flags); \ 344 } while (0) 345 346 #define put_user(x, ptr) \ 347 ({ \ 348 int __pu_err = 0; \ 349 __put_user_switch((x), (ptr), __pu_err, __put_user_check); \ 350 __pu_err; \ 351 }) 352 353 #define __put_user(x, ptr) \ 354 ({ \ 355 long __pu_err = 0; \ 356 __put_user_switch((x), (ptr), __pu_err, __put_user_nocheck); \ 357 __pu_err; \ 358 }) 359 360 #define __put_user_error(x, ptr, err) \ 361 ({ \ 362 __put_user_switch((x), (ptr), (err), __put_user_nocheck); \ 363 (void) 0; \ 364 }) 365 366 #define __put_user_nocheck(x, __pu_ptr, __err, __size) \ 367 do { \ 368 unsigned long __pu_addr = (unsigned long)__pu_ptr; \ 369 __put_user_nocheck_##__size(x, __pu_addr, __err); \ 370 } while (0) 371 372 #define __put_user_nocheck_1 __put_user_asm_byte 373 #define __put_user_nocheck_2 __put_user_asm_half 374 #define __put_user_nocheck_4 __put_user_asm_word 375 #define __put_user_nocheck_8 __put_user_asm_dword 376 377 #define __put_user_asm(x, __pu_addr, err, instr) \ 378 __asm__ __volatile__( \ 379 "1: " TUSER(instr) " %1, [%2], #0\n" \ 380 "2:\n" \ 381 " .pushsection .text.fixup,\"ax\"\n" \ 382 " .align 2\n" \ 383 "3: mov %0, %3\n" \ 384 " b 2b\n" \ 385 " .popsection\n" \ 386 " .pushsection __ex_table,\"a\"\n" \ 387 " .align 3\n" \ 388 " .long 1b, 3b\n" \ 389 " .popsection" \ 390 : "+r" (err) \ 391 : "r" (x), "r" (__pu_addr), "i" (-EFAULT) \ 392 : "cc") 393 394 #define __put_user_asm_byte(x, __pu_addr, err) \ 395 __put_user_asm(x, __pu_addr, err, strb) 396 397 #ifndef __ARMEB__ 398 #define __put_user_asm_half(x, __pu_addr, err) \ 399 ({ \ 400 unsigned long __temp = (__force unsigned long)(x); \ 401 __put_user_asm_byte(__temp, __pu_addr, err); \ 402 __put_user_asm_byte(__temp >> 8, __pu_addr + 1, err); \ 403 }) 404 #else 405 #define __put_user_asm_half(x, __pu_addr, err) \ 406 ({ \ 407 unsigned long __temp = (__force unsigned long)(x); \ 408 __put_user_asm_byte(__temp >> 8, __pu_addr, err); \ 409 __put_user_asm_byte(__temp, __pu_addr + 1, err); \ 410 }) 411 #endif 412 413 #define __put_user_asm_word(x, __pu_addr, err) \ 414 __put_user_asm(x, __pu_addr, err, str) 415 416 #ifndef __ARMEB__ 417 #define __reg_oper0 "%R2" 418 #define __reg_oper1 "%Q2" 419 #else 420 #define __reg_oper0 "%Q2" 421 #define __reg_oper1 "%R2" 422 #endif 423 424 #define __put_user_asm_dword(x, __pu_addr, err) \ 425 __asm__ __volatile__( \ 426 ARM( "1: " TUSER(str) " " __reg_oper1 ", [%1], #4\n" ) \ 427 ARM( "2: " TUSER(str) " " __reg_oper0 ", [%1]\n" ) \ 428 THUMB( "1: " TUSER(str) " " __reg_oper1 ", [%1]\n" ) \ 429 THUMB( "2: " TUSER(str) " " __reg_oper0 ", [%1, #4]\n" ) \ 430 "3:\n" \ 431 " .pushsection .text.fixup,\"ax\"\n" \ 432 " .align 2\n" \ 433 "4: mov %0, %3\n" \ 434 " b 3b\n" \ 435 " .popsection\n" \ 436 " .pushsection __ex_table,\"a\"\n" \ 437 " .align 3\n" \ 438 " .long 1b, 4b\n" \ 439 " .long 2b, 4b\n" \ 440 " .popsection" \ 441 : "+r" (err), "+r" (__pu_addr) \ 442 : "r" (x), "i" (-EFAULT) \ 443 : "cc") 444 445 446 #ifdef CONFIG_MMU 447 extern unsigned long __must_check 448 arm_copy_from_user(void *to, const void __user *from, unsigned long n); 449 450 static inline unsigned long __must_check 451 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 452 { 453 unsigned int __ua_flags; 454 455 __ua_flags = uaccess_save_and_enable(); 456 n = arm_copy_from_user(to, from, n); 457 uaccess_restore(__ua_flags); 458 return n; 459 } 460 461 extern unsigned long __must_check 462 arm_copy_to_user(void __user *to, const void *from, unsigned long n); 463 extern unsigned long __must_check 464 __copy_to_user_std(void __user *to, const void *from, unsigned long n); 465 466 static inline unsigned long __must_check 467 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 468 { 469 #ifndef CONFIG_UACCESS_WITH_MEMCPY 470 unsigned int __ua_flags; 471 __ua_flags = uaccess_save_and_enable(); 472 n = arm_copy_to_user(to, from, n); 473 uaccess_restore(__ua_flags); 474 return n; 475 #else 476 return arm_copy_to_user(to, from, n); 477 #endif 478 } 479 480 extern unsigned long __must_check 481 arm_clear_user(void __user *addr, unsigned long n); 482 extern unsigned long __must_check 483 __clear_user_std(void __user *addr, unsigned long n); 484 485 static inline unsigned long __must_check 486 __clear_user(void __user *addr, unsigned long n) 487 { 488 unsigned int __ua_flags = uaccess_save_and_enable(); 489 n = arm_clear_user(addr, n); 490 uaccess_restore(__ua_flags); 491 return n; 492 } 493 494 #else 495 static inline unsigned long 496 raw_copy_from_user(void *to, const void __user *from, unsigned long n) 497 { 498 memcpy(to, (const void __force *)from, n); 499 return 0; 500 } 501 static inline unsigned long 502 raw_copy_to_user(void __user *to, const void *from, unsigned long n) 503 { 504 memcpy((void __force *)to, from, n); 505 return 0; 506 } 507 #define __clear_user(addr, n) (memset((void __force *)addr, 0, n), 0) 508 #endif 509 #define INLINE_COPY_TO_USER 510 #define INLINE_COPY_FROM_USER 511 512 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 513 { 514 if (access_ok(VERIFY_WRITE, to, n)) 515 n = __clear_user(to, n); 516 return n; 517 } 518 519 /* These are from lib/ code, and use __get_user() and friends */ 520 extern long strncpy_from_user(char *dest, const char __user *src, long count); 521 522 extern __must_check long strnlen_user(const char __user *str, long n); 523 524 #endif /* _ASMARM_UACCESS_H */ 525