1 /* SPDX-License-Identifier: GPL-2.0-only */ 2 /* 3 * Based on arch/arm/include/asm/uaccess.h 4 * 5 * Copyright (C) 2012 ARM Ltd. 6 */ 7 #ifndef __ASM_UACCESS_H 8 #define __ASM_UACCESS_H 9 10 #include <asm/alternative.h> 11 #include <asm/kernel-pgtable.h> 12 #include <asm/sysreg.h> 13 14 /* 15 * User space memory access functions 16 */ 17 #include <linux/bitops.h> 18 #include <linux/kasan-checks.h> 19 #include <linux/string.h> 20 21 #include <asm/asm-extable.h> 22 #include <asm/cpufeature.h> 23 #include <asm/mmu.h> 24 #include <asm/mte.h> 25 #include <asm/ptrace.h> 26 #include <asm/memory.h> 27 #include <asm/extable.h> 28 29 static inline int __access_ok(const void __user *ptr, unsigned long size); 30 31 /* 32 * Test whether a block of memory is a valid user space address. 33 * Returns 1 if the range is valid, 0 otherwise. 34 * 35 * This is equivalent to the following test: 36 * (u65)addr + (u65)size <= (u65)TASK_SIZE_MAX 37 */ 38 static inline int access_ok(const void __user *addr, unsigned long size) 39 { 40 /* 41 * Asynchronous I/O running in a kernel thread does not have the 42 * TIF_TAGGED_ADDR flag of the process owning the mm, so always untag 43 * the user address before checking. 44 */ 45 if (IS_ENABLED(CONFIG_ARM64_TAGGED_ADDR_ABI) && 46 (current->flags & PF_KTHREAD || test_thread_flag(TIF_TAGGED_ADDR))) 47 addr = untagged_addr(addr); 48 49 return likely(__access_ok(addr, size)); 50 } 51 #define access_ok access_ok 52 53 #include <asm-generic/access_ok.h> 54 55 /* 56 * User access enabling/disabling. 57 */ 58 #ifdef CONFIG_ARM64_SW_TTBR0_PAN 59 static inline void __uaccess_ttbr0_disable(void) 60 { 61 unsigned long flags, ttbr; 62 63 local_irq_save(flags); 64 ttbr = read_sysreg(ttbr1_el1); 65 ttbr &= ~TTBR_ASID_MASK; 66 /* reserved_pg_dir placed before swapper_pg_dir */ 67 write_sysreg(ttbr - RESERVED_SWAPPER_OFFSET, ttbr0_el1); 68 /* Set reserved ASID */ 69 write_sysreg(ttbr, ttbr1_el1); 70 isb(); 71 local_irq_restore(flags); 72 } 73 74 static inline void __uaccess_ttbr0_enable(void) 75 { 76 unsigned long flags, ttbr0, ttbr1; 77 78 /* 79 * Disable interrupts to avoid preemption between reading the 'ttbr0' 80 * variable and the MSR. A context switch could trigger an ASID 81 * roll-over and an update of 'ttbr0'. 82 */ 83 local_irq_save(flags); 84 ttbr0 = READ_ONCE(current_thread_info()->ttbr0); 85 86 /* Restore active ASID */ 87 ttbr1 = read_sysreg(ttbr1_el1); 88 ttbr1 &= ~TTBR_ASID_MASK; /* safety measure */ 89 ttbr1 |= ttbr0 & TTBR_ASID_MASK; 90 write_sysreg(ttbr1, ttbr1_el1); 91 92 /* Restore user page table */ 93 write_sysreg(ttbr0, ttbr0_el1); 94 isb(); 95 local_irq_restore(flags); 96 } 97 98 static inline bool uaccess_ttbr0_disable(void) 99 { 100 if (!system_uses_ttbr0_pan()) 101 return false; 102 __uaccess_ttbr0_disable(); 103 return true; 104 } 105 106 static inline bool uaccess_ttbr0_enable(void) 107 { 108 if (!system_uses_ttbr0_pan()) 109 return false; 110 __uaccess_ttbr0_enable(); 111 return true; 112 } 113 #else 114 static inline bool uaccess_ttbr0_disable(void) 115 { 116 return false; 117 } 118 119 static inline bool uaccess_ttbr0_enable(void) 120 { 121 return false; 122 } 123 #endif 124 125 static inline void __uaccess_disable_hw_pan(void) 126 { 127 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, 128 CONFIG_ARM64_PAN)); 129 } 130 131 static inline void __uaccess_enable_hw_pan(void) 132 { 133 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, 134 CONFIG_ARM64_PAN)); 135 } 136 137 static inline void uaccess_disable_privileged(void) 138 { 139 mte_disable_tco(); 140 141 if (uaccess_ttbr0_disable()) 142 return; 143 144 __uaccess_enable_hw_pan(); 145 } 146 147 static inline void uaccess_enable_privileged(void) 148 { 149 mte_enable_tco(); 150 151 if (uaccess_ttbr0_enable()) 152 return; 153 154 __uaccess_disable_hw_pan(); 155 } 156 157 /* 158 * Sanitize a uaccess pointer such that it cannot reach any kernel address. 159 * 160 * Clearing bit 55 ensures the pointer cannot address any portion of the TTBR1 161 * address range (i.e. any kernel address), and either the pointer falls within 162 * the TTBR0 address range or must cause a fault. 163 */ 164 #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr) 165 static inline void __user *__uaccess_mask_ptr(const void __user *ptr) 166 { 167 void __user *safe_ptr; 168 169 asm volatile( 170 " bic %0, %1, %2\n" 171 : "=r" (safe_ptr) 172 : "r" (ptr), 173 "i" (BIT(55)) 174 ); 175 176 return safe_ptr; 177 } 178 179 /* 180 * The "__xxx" versions of the user access functions do not verify the address 181 * space - it must have been done previously with a separate "access_ok()" 182 * call. 183 * 184 * The "__xxx_error" versions set the third argument to -EFAULT if an error 185 * occurs, and leave it unchanged on success. 186 */ 187 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT 188 #define __get_mem_asm(load, reg, x, addr, label, type) \ 189 asm_goto_output( \ 190 "1: " load " " reg "0, [%1]\n" \ 191 _ASM_EXTABLE_##type##ACCESS(1b, %l2) \ 192 : "=r" (x) \ 193 : "r" (addr) : : label) 194 #else 195 #define __get_mem_asm(load, reg, x, addr, label, type) do { \ 196 int __gma_err = 0; \ 197 asm volatile( \ 198 "1: " load " " reg "1, [%2]\n" \ 199 "2:\n" \ 200 _ASM_EXTABLE_##type##ACCESS_ERR_ZERO(1b, 2b, %w0, %w1) \ 201 : "+r" (__gma_err), "=r" (x) \ 202 : "r" (addr)); \ 203 if (__gma_err) goto label; } while (0) 204 #endif 205 206 #define __raw_get_mem(ldr, x, ptr, label, type) \ 207 do { \ 208 unsigned long __gu_val; \ 209 switch (sizeof(*(ptr))) { \ 210 case 1: \ 211 __get_mem_asm(ldr "b", "%w", __gu_val, (ptr), label, type); \ 212 break; \ 213 case 2: \ 214 __get_mem_asm(ldr "h", "%w", __gu_val, (ptr), label, type); \ 215 break; \ 216 case 4: \ 217 __get_mem_asm(ldr, "%w", __gu_val, (ptr), label, type); \ 218 break; \ 219 case 8: \ 220 __get_mem_asm(ldr, "%x", __gu_val, (ptr), label, type); \ 221 break; \ 222 default: \ 223 BUILD_BUG(); \ 224 } \ 225 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 226 } while (0) 227 228 /* 229 * We must not call into the scheduler between uaccess_ttbr0_enable() and 230 * uaccess_ttbr0_disable(). As `x` and `ptr` could contain blocking functions, 231 * we must evaluate these outside of the critical section. 232 */ 233 #define __raw_get_user(x, ptr, label) \ 234 do { \ 235 __typeof__(*(ptr)) __user *__rgu_ptr = (ptr); \ 236 __typeof__(x) __rgu_val; \ 237 __chk_user_ptr(ptr); \ 238 do { \ 239 __label__ __rgu_failed; \ 240 uaccess_ttbr0_enable(); \ 241 __raw_get_mem("ldtr", __rgu_val, __rgu_ptr, __rgu_failed, U); \ 242 uaccess_ttbr0_disable(); \ 243 (x) = __rgu_val; \ 244 break; \ 245 __rgu_failed: \ 246 uaccess_ttbr0_disable(); \ 247 goto label; \ 248 } while (0); \ 249 } while (0) 250 251 #define __get_user_error(x, ptr, err) \ 252 do { \ 253 __label__ __gu_failed; \ 254 __typeof__(*(ptr)) __user *__p = (ptr); \ 255 might_fault(); \ 256 if (access_ok(__p, sizeof(*__p))) { \ 257 __p = uaccess_mask_ptr(__p); \ 258 __raw_get_user((x), __p, __gu_failed); \ 259 } else { \ 260 __gu_failed: \ 261 (x) = (__force __typeof__(x))0; (err) = -EFAULT; \ 262 } \ 263 } while (0) 264 265 #define __get_user(x, ptr) \ 266 ({ \ 267 int __gu_err = 0; \ 268 __get_user_error((x), (ptr), __gu_err); \ 269 __gu_err; \ 270 }) 271 272 #define get_user __get_user 273 274 /* 275 * We must not call into the scheduler between __mte_enable_tco_async() and 276 * __mte_disable_tco_async(). As `dst` and `src` may contain blocking 277 * functions, we must evaluate these outside of the critical section. 278 */ 279 #define __get_kernel_nofault(dst, src, type, err_label) \ 280 do { \ 281 __typeof__(dst) __gkn_dst = (dst); \ 282 __typeof__(src) __gkn_src = (src); \ 283 do { \ 284 __label__ __gkn_label; \ 285 \ 286 __mte_enable_tco_async(); \ 287 __raw_get_mem("ldr", *((type *)(__gkn_dst)), \ 288 (__force type *)(__gkn_src), __gkn_label, K); \ 289 __mte_disable_tco_async(); \ 290 break; \ 291 __gkn_label: \ 292 __mte_disable_tco_async(); \ 293 goto err_label; \ 294 } while (0); \ 295 } while (0) 296 297 #define __put_mem_asm(store, reg, x, addr, label, type) \ 298 asm goto( \ 299 "1: " store " " reg "0, [%1]\n" \ 300 "2:\n" \ 301 _ASM_EXTABLE_##type##ACCESS(1b, %l2) \ 302 : : "rZ" (x), "r" (addr) : : label) 303 304 #define __raw_put_mem(str, x, ptr, label, type) \ 305 do { \ 306 __typeof__(*(ptr)) __pu_val = (x); \ 307 switch (sizeof(*(ptr))) { \ 308 case 1: \ 309 __put_mem_asm(str "b", "%w", __pu_val, (ptr), label, type); \ 310 break; \ 311 case 2: \ 312 __put_mem_asm(str "h", "%w", __pu_val, (ptr), label, type); \ 313 break; \ 314 case 4: \ 315 __put_mem_asm(str, "%w", __pu_val, (ptr), label, type); \ 316 break; \ 317 case 8: \ 318 __put_mem_asm(str, "%x", __pu_val, (ptr), label, type); \ 319 break; \ 320 default: \ 321 BUILD_BUG(); \ 322 } \ 323 } while (0) 324 325 /* 326 * We must not call into the scheduler between uaccess_ttbr0_enable() and 327 * uaccess_ttbr0_disable(). As `x` and `ptr` could contain blocking functions, 328 * we must evaluate these outside of the critical section. 329 */ 330 #define __raw_put_user(x, ptr, label) \ 331 do { \ 332 __label__ __rpu_failed; \ 333 __typeof__(*(ptr)) __user *__rpu_ptr = (ptr); \ 334 __typeof__(*(ptr)) __rpu_val = (x); \ 335 __chk_user_ptr(__rpu_ptr); \ 336 \ 337 do { \ 338 uaccess_ttbr0_enable(); \ 339 __raw_put_mem("sttr", __rpu_val, __rpu_ptr, __rpu_failed, U); \ 340 uaccess_ttbr0_disable(); \ 341 break; \ 342 __rpu_failed: \ 343 uaccess_ttbr0_disable(); \ 344 goto label; \ 345 } while (0); \ 346 } while (0) 347 348 #define __put_user_error(x, ptr, err) \ 349 do { \ 350 __label__ __pu_failed; \ 351 __typeof__(*(ptr)) __user *__p = (ptr); \ 352 might_fault(); \ 353 if (access_ok(__p, sizeof(*__p))) { \ 354 __p = uaccess_mask_ptr(__p); \ 355 __raw_put_user((x), __p, __pu_failed); \ 356 } else { \ 357 __pu_failed: \ 358 (err) = -EFAULT; \ 359 } \ 360 } while (0) 361 362 #define __put_user(x, ptr) \ 363 ({ \ 364 int __pu_err = 0; \ 365 __put_user_error((x), (ptr), __pu_err); \ 366 __pu_err; \ 367 }) 368 369 #define put_user __put_user 370 371 /* 372 * We must not call into the scheduler between __mte_enable_tco_async() and 373 * __mte_disable_tco_async(). As `dst` and `src` may contain blocking 374 * functions, we must evaluate these outside of the critical section. 375 */ 376 #define __put_kernel_nofault(dst, src, type, err_label) \ 377 do { \ 378 __typeof__(dst) __pkn_dst = (dst); \ 379 __typeof__(src) __pkn_src = (src); \ 380 \ 381 do { \ 382 __label__ __pkn_err; \ 383 __mte_enable_tco_async(); \ 384 __raw_put_mem("str", *((type *)(__pkn_src)), \ 385 (__force type *)(__pkn_dst), __pkn_err, K); \ 386 __mte_disable_tco_async(); \ 387 break; \ 388 __pkn_err: \ 389 __mte_disable_tco_async(); \ 390 goto err_label; \ 391 } while (0); \ 392 } while(0) 393 394 extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); 395 #define raw_copy_from_user(to, from, n) \ 396 ({ \ 397 unsigned long __acfu_ret; \ 398 uaccess_ttbr0_enable(); \ 399 __acfu_ret = __arch_copy_from_user((to), \ 400 __uaccess_mask_ptr(from), (n)); \ 401 uaccess_ttbr0_disable(); \ 402 __acfu_ret; \ 403 }) 404 405 extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); 406 #define raw_copy_to_user(to, from, n) \ 407 ({ \ 408 unsigned long __actu_ret; \ 409 uaccess_ttbr0_enable(); \ 410 __actu_ret = __arch_copy_to_user(__uaccess_mask_ptr(to), \ 411 (from), (n)); \ 412 uaccess_ttbr0_disable(); \ 413 __actu_ret; \ 414 }) 415 416 static __must_check __always_inline bool user_access_begin(const void __user *ptr, size_t len) 417 { 418 if (unlikely(!access_ok(ptr,len))) 419 return 0; 420 uaccess_ttbr0_enable(); 421 return 1; 422 } 423 #define user_access_begin(a,b) user_access_begin(a,b) 424 #define user_access_end() uaccess_ttbr0_disable() 425 #define unsafe_put_user(x, ptr, label) \ 426 __raw_put_mem("sttr", x, uaccess_mask_ptr(ptr), label, U) 427 #define unsafe_get_user(x, ptr, label) \ 428 __raw_get_mem("ldtr", x, uaccess_mask_ptr(ptr), label, U) 429 430 /* 431 * KCSAN uses these to save and restore ttbr state. 432 * We do not support KCSAN with ARM64_SW_TTBR0_PAN, so 433 * they are no-ops. 434 */ 435 static inline unsigned long user_access_save(void) { return 0; } 436 static inline void user_access_restore(unsigned long enabled) { } 437 438 /* 439 * We want the unsafe accessors to always be inlined and use 440 * the error labels - thus the macro games. 441 */ 442 #define unsafe_copy_loop(dst, src, len, type, label) \ 443 while (len >= sizeof(type)) { \ 444 unsafe_put_user(*(type *)(src),(type __user *)(dst),label); \ 445 dst += sizeof(type); \ 446 src += sizeof(type); \ 447 len -= sizeof(type); \ 448 } 449 450 #define unsafe_copy_to_user(_dst,_src,_len,label) \ 451 do { \ 452 char __user *__ucu_dst = (_dst); \ 453 const char *__ucu_src = (_src); \ 454 size_t __ucu_len = (_len); \ 455 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u64, label); \ 456 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u32, label); \ 457 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u16, label); \ 458 unsafe_copy_loop(__ucu_dst, __ucu_src, __ucu_len, u8, label); \ 459 } while (0) 460 461 #define INLINE_COPY_TO_USER 462 #define INLINE_COPY_FROM_USER 463 464 extern unsigned long __must_check __arch_clear_user(void __user *to, unsigned long n); 465 static inline unsigned long __must_check __clear_user(void __user *to, unsigned long n) 466 { 467 if (access_ok(to, n)) { 468 uaccess_ttbr0_enable(); 469 n = __arch_clear_user(__uaccess_mask_ptr(to), n); 470 uaccess_ttbr0_disable(); 471 } 472 return n; 473 } 474 #define clear_user __clear_user 475 476 extern long strncpy_from_user(char *dest, const char __user *src, long count); 477 478 extern __must_check long strnlen_user(const char __user *str, long n); 479 480 #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE 481 extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n); 482 483 static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size) 484 { 485 kasan_check_write(dst, size); 486 return __copy_user_flushcache(dst, __uaccess_mask_ptr(src), size); 487 } 488 #endif 489 490 #ifdef CONFIG_ARCH_HAS_SUBPAGE_FAULTS 491 492 /* 493 * Return 0 on success, the number of bytes not probed otherwise. 494 */ 495 static inline size_t probe_subpage_writeable(const char __user *uaddr, 496 size_t size) 497 { 498 if (!system_supports_mte()) 499 return 0; 500 return mte_probe_user_range(uaddr, size); 501 } 502 503 #endif /* CONFIG_ARCH_HAS_SUBPAGE_FAULTS */ 504 505 #endif /* __ASM_UACCESS_H */ 506