1 /* 2 * Based on arch/arm/include/asm/uaccess.h 3 * 4 * Copyright (C) 2012 ARM Ltd. 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 * 15 * You should have received a copy of the GNU General Public License 16 * along with this program. If not, see <http://www.gnu.org/licenses/>. 17 */ 18 #ifndef __ASM_UACCESS_H 19 #define __ASM_UACCESS_H 20 21 #include <asm/alternative.h> 22 #include <asm/kernel-pgtable.h> 23 #include <asm/sysreg.h> 24 25 /* 26 * User space memory access functions 27 */ 28 #include <linux/bitops.h> 29 #include <linux/kasan-checks.h> 30 #include <linux/string.h> 31 32 #include <asm/cpufeature.h> 33 #include <asm/ptrace.h> 34 #include <asm/memory.h> 35 #include <asm/compiler.h> 36 #include <asm/extable.h> 37 38 #define KERNEL_DS (-1UL) 39 #define get_ds() (KERNEL_DS) 40 41 #define USER_DS TASK_SIZE_64 42 #define get_fs() (current_thread_info()->addr_limit) 43 44 static inline void set_fs(mm_segment_t fs) 45 { 46 current_thread_info()->addr_limit = fs; 47 48 /* 49 * Enable/disable UAO so that copy_to_user() etc can access 50 * kernel memory with the unprivileged instructions. 51 */ 52 if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS) 53 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO)); 54 else 55 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO, 56 CONFIG_ARM64_UAO)); 57 } 58 59 #define segment_eq(a, b) ((a) == (b)) 60 61 /* 62 * Test whether a block of memory is a valid user space address. 63 * Returns 1 if the range is valid, 0 otherwise. 64 * 65 * This is equivalent to the following test: 66 * (u65)addr + (u65)size <= current->addr_limit 67 * 68 * This needs 65-bit arithmetic. 69 */ 70 #define __range_ok(addr, size) \ 71 ({ \ 72 unsigned long flag, roksum; \ 73 __chk_user_ptr(addr); \ 74 asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ 75 : "=&r" (flag), "=&r" (roksum) \ 76 : "1" (addr), "Ir" (size), \ 77 "r" (current_thread_info()->addr_limit) \ 78 : "cc"); \ 79 flag; \ 80 }) 81 82 /* 83 * When dealing with data aborts or instruction traps we may end up with 84 * a tagged userland pointer. Clear the tag to get a sane pointer to pass 85 * on to access_ok(), for instance. 86 */ 87 #define untagged_addr(addr) sign_extend64(addr, 55) 88 89 #define access_ok(type, addr, size) __range_ok(addr, size) 90 #define user_addr_max get_fs 91 92 #define _ASM_EXTABLE(from, to) \ 93 " .pushsection __ex_table, \"a\"\n" \ 94 " .align 3\n" \ 95 " .long (" #from " - .), (" #to " - .)\n" \ 96 " .popsection\n" 97 98 /* 99 * User access enabling/disabling. 100 */ 101 #ifdef CONFIG_ARM64_SW_TTBR0_PAN 102 static inline void __uaccess_ttbr0_disable(void) 103 { 104 unsigned long ttbr; 105 106 /* reserved_ttbr0 placed at the end of swapper_pg_dir */ 107 ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE; 108 write_sysreg(ttbr, ttbr0_el1); 109 isb(); 110 } 111 112 static inline void __uaccess_ttbr0_enable(void) 113 { 114 unsigned long flags; 115 116 /* 117 * Disable interrupts to avoid preemption between reading the 'ttbr0' 118 * variable and the MSR. A context switch could trigger an ASID 119 * roll-over and an update of 'ttbr0'. 120 */ 121 local_irq_save(flags); 122 write_sysreg(current_thread_info()->ttbr0, ttbr0_el1); 123 isb(); 124 local_irq_restore(flags); 125 } 126 127 static inline bool uaccess_ttbr0_disable(void) 128 { 129 if (!system_uses_ttbr0_pan()) 130 return false; 131 __uaccess_ttbr0_disable(); 132 return true; 133 } 134 135 static inline bool uaccess_ttbr0_enable(void) 136 { 137 if (!system_uses_ttbr0_pan()) 138 return false; 139 __uaccess_ttbr0_enable(); 140 return true; 141 } 142 #else 143 static inline bool uaccess_ttbr0_disable(void) 144 { 145 return false; 146 } 147 148 static inline bool uaccess_ttbr0_enable(void) 149 { 150 return false; 151 } 152 #endif 153 154 #define __uaccess_disable(alt) \ 155 do { \ 156 if (!uaccess_ttbr0_disable()) \ 157 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \ 158 CONFIG_ARM64_PAN)); \ 159 } while (0) 160 161 #define __uaccess_enable(alt) \ 162 do { \ 163 if (!uaccess_ttbr0_enable()) \ 164 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \ 165 CONFIG_ARM64_PAN)); \ 166 } while (0) 167 168 static inline void uaccess_disable(void) 169 { 170 __uaccess_disable(ARM64_HAS_PAN); 171 } 172 173 static inline void uaccess_enable(void) 174 { 175 __uaccess_enable(ARM64_HAS_PAN); 176 } 177 178 /* 179 * These functions are no-ops when UAO is present. 180 */ 181 static inline void uaccess_disable_not_uao(void) 182 { 183 __uaccess_disable(ARM64_ALT_PAN_NOT_UAO); 184 } 185 186 static inline void uaccess_enable_not_uao(void) 187 { 188 __uaccess_enable(ARM64_ALT_PAN_NOT_UAO); 189 } 190 191 /* 192 * The "__xxx" versions of the user access functions do not verify the address 193 * space - it must have been done previously with a separate "access_ok()" 194 * call. 195 * 196 * The "__xxx_error" versions set the third argument to -EFAULT if an error 197 * occurs, and leave it unchanged on success. 198 */ 199 #define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 200 asm volatile( \ 201 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 202 alt_instr " " reg "1, [%2]\n", feature) \ 203 "2:\n" \ 204 " .section .fixup, \"ax\"\n" \ 205 " .align 2\n" \ 206 "3: mov %w0, %3\n" \ 207 " mov %1, #0\n" \ 208 " b 2b\n" \ 209 " .previous\n" \ 210 _ASM_EXTABLE(1b, 3b) \ 211 : "+r" (err), "=&r" (x) \ 212 : "r" (addr), "i" (-EFAULT)) 213 214 #define __get_user_err(x, ptr, err) \ 215 do { \ 216 unsigned long __gu_val; \ 217 __chk_user_ptr(ptr); \ 218 uaccess_enable_not_uao(); \ 219 switch (sizeof(*(ptr))) { \ 220 case 1: \ 221 __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ 222 (err), ARM64_HAS_UAO); \ 223 break; \ 224 case 2: \ 225 __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ 226 (err), ARM64_HAS_UAO); \ 227 break; \ 228 case 4: \ 229 __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ 230 (err), ARM64_HAS_UAO); \ 231 break; \ 232 case 8: \ 233 __get_user_asm("ldr", "ldtr", "%", __gu_val, (ptr), \ 234 (err), ARM64_HAS_UAO); \ 235 break; \ 236 default: \ 237 BUILD_BUG(); \ 238 } \ 239 uaccess_disable_not_uao(); \ 240 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 241 } while (0) 242 243 #define __get_user(x, ptr) \ 244 ({ \ 245 int __gu_err = 0; \ 246 __get_user_err((x), (ptr), __gu_err); \ 247 __gu_err; \ 248 }) 249 250 #define __get_user_error(x, ptr, err) \ 251 ({ \ 252 __get_user_err((x), (ptr), (err)); \ 253 (void)0; \ 254 }) 255 256 #define __get_user_unaligned __get_user 257 258 #define get_user(x, ptr) \ 259 ({ \ 260 __typeof__(*(ptr)) __user *__p = (ptr); \ 261 might_fault(); \ 262 access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ 263 __get_user((x), __p) : \ 264 ((x) = 0, -EFAULT); \ 265 }) 266 267 #define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 268 asm volatile( \ 269 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 270 alt_instr " " reg "1, [%2]\n", feature) \ 271 "2:\n" \ 272 " .section .fixup,\"ax\"\n" \ 273 " .align 2\n" \ 274 "3: mov %w0, %3\n" \ 275 " b 2b\n" \ 276 " .previous\n" \ 277 _ASM_EXTABLE(1b, 3b) \ 278 : "+r" (err) \ 279 : "r" (x), "r" (addr), "i" (-EFAULT)) 280 281 #define __put_user_err(x, ptr, err) \ 282 do { \ 283 __typeof__(*(ptr)) __pu_val = (x); \ 284 __chk_user_ptr(ptr); \ 285 uaccess_enable_not_uao(); \ 286 switch (sizeof(*(ptr))) { \ 287 case 1: \ 288 __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ 289 (err), ARM64_HAS_UAO); \ 290 break; \ 291 case 2: \ 292 __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ 293 (err), ARM64_HAS_UAO); \ 294 break; \ 295 case 4: \ 296 __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ 297 (err), ARM64_HAS_UAO); \ 298 break; \ 299 case 8: \ 300 __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ 301 (err), ARM64_HAS_UAO); \ 302 break; \ 303 default: \ 304 BUILD_BUG(); \ 305 } \ 306 uaccess_disable_not_uao(); \ 307 } while (0) 308 309 #define __put_user(x, ptr) \ 310 ({ \ 311 int __pu_err = 0; \ 312 __put_user_err((x), (ptr), __pu_err); \ 313 __pu_err; \ 314 }) 315 316 #define __put_user_error(x, ptr, err) \ 317 ({ \ 318 __put_user_err((x), (ptr), (err)); \ 319 (void)0; \ 320 }) 321 322 #define __put_user_unaligned __put_user 323 324 #define put_user(x, ptr) \ 325 ({ \ 326 __typeof__(*(ptr)) __user *__p = (ptr); \ 327 might_fault(); \ 328 access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ 329 __put_user((x), __p) : \ 330 -EFAULT; \ 331 }) 332 333 extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); 334 #define raw_copy_from_user __arch_copy_from_user 335 extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); 336 #define raw_copy_to_user __arch_copy_to_user 337 extern unsigned long __must_check raw_copy_in_user(void __user *to, const void __user *from, unsigned long n); 338 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 339 #define INLINE_COPY_TO_USER 340 #define INLINE_COPY_FROM_USER 341 342 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 343 { 344 if (access_ok(VERIFY_WRITE, to, n)) 345 n = __clear_user(to, n); 346 return n; 347 } 348 349 extern long strncpy_from_user(char *dest, const char __user *src, long count); 350 351 extern __must_check long strlen_user(const char __user *str); 352 extern __must_check long strnlen_user(const char __user *str, long n); 353 354 #endif /* __ASM_UACCESS_H */ 355