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 __addr = (unsigned long)(addr); \ 73 unsigned long flag, roksum; \ 74 __chk_user_ptr(addr); \ 75 asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ 76 : "=&r" (flag), "=&r" (roksum) \ 77 : "1" (__addr), "Ir" (size), \ 78 "r" (current_thread_info()->addr_limit) \ 79 : "cc"); \ 80 flag; \ 81 }) 82 83 /* 84 * When dealing with data aborts, watchpoints, or instruction traps we may end 85 * up with a tagged userland pointer. Clear the tag to get a sane pointer to 86 * pass on to access_ok(), for instance. 87 */ 88 #define untagged_addr(addr) sign_extend64(addr, 55) 89 90 #define access_ok(type, addr, size) __range_ok(addr, size) 91 #define user_addr_max get_fs 92 93 #define _ASM_EXTABLE(from, to) \ 94 " .pushsection __ex_table, \"a\"\n" \ 95 " .align 3\n" \ 96 " .long (" #from " - .), (" #to " - .)\n" \ 97 " .popsection\n" 98 99 /* 100 * User access enabling/disabling. 101 */ 102 #ifdef CONFIG_ARM64_SW_TTBR0_PAN 103 static inline void __uaccess_ttbr0_disable(void) 104 { 105 unsigned long ttbr; 106 107 /* reserved_ttbr0 placed at the end of swapper_pg_dir */ 108 ttbr = read_sysreg(ttbr1_el1) + SWAPPER_DIR_SIZE; 109 write_sysreg(ttbr, ttbr0_el1); 110 isb(); 111 } 112 113 static inline void __uaccess_ttbr0_enable(void) 114 { 115 unsigned long flags; 116 117 /* 118 * Disable interrupts to avoid preemption between reading the 'ttbr0' 119 * variable and the MSR. A context switch could trigger an ASID 120 * roll-over and an update of 'ttbr0'. 121 */ 122 local_irq_save(flags); 123 write_sysreg(current_thread_info()->ttbr0, ttbr0_el1); 124 isb(); 125 local_irq_restore(flags); 126 } 127 128 static inline bool uaccess_ttbr0_disable(void) 129 { 130 if (!system_uses_ttbr0_pan()) 131 return false; 132 __uaccess_ttbr0_disable(); 133 return true; 134 } 135 136 static inline bool uaccess_ttbr0_enable(void) 137 { 138 if (!system_uses_ttbr0_pan()) 139 return false; 140 __uaccess_ttbr0_enable(); 141 return true; 142 } 143 #else 144 static inline bool uaccess_ttbr0_disable(void) 145 { 146 return false; 147 } 148 149 static inline bool uaccess_ttbr0_enable(void) 150 { 151 return false; 152 } 153 #endif 154 155 #define __uaccess_disable(alt) \ 156 do { \ 157 if (!uaccess_ttbr0_disable()) \ 158 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), alt, \ 159 CONFIG_ARM64_PAN)); \ 160 } while (0) 161 162 #define __uaccess_enable(alt) \ 163 do { \ 164 if (!uaccess_ttbr0_enable()) \ 165 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), alt, \ 166 CONFIG_ARM64_PAN)); \ 167 } while (0) 168 169 static inline void uaccess_disable(void) 170 { 171 __uaccess_disable(ARM64_HAS_PAN); 172 } 173 174 static inline void uaccess_enable(void) 175 { 176 __uaccess_enable(ARM64_HAS_PAN); 177 } 178 179 /* 180 * These functions are no-ops when UAO is present. 181 */ 182 static inline void uaccess_disable_not_uao(void) 183 { 184 __uaccess_disable(ARM64_ALT_PAN_NOT_UAO); 185 } 186 187 static inline void uaccess_enable_not_uao(void) 188 { 189 __uaccess_enable(ARM64_ALT_PAN_NOT_UAO); 190 } 191 192 /* 193 * The "__xxx" versions of the user access functions do not verify the address 194 * space - it must have been done previously with a separate "access_ok()" 195 * call. 196 * 197 * The "__xxx_error" versions set the third argument to -EFAULT if an error 198 * occurs, and leave it unchanged on success. 199 */ 200 #define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 201 asm volatile( \ 202 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 203 alt_instr " " reg "1, [%2]\n", feature) \ 204 "2:\n" \ 205 " .section .fixup, \"ax\"\n" \ 206 " .align 2\n" \ 207 "3: mov %w0, %3\n" \ 208 " mov %1, #0\n" \ 209 " b 2b\n" \ 210 " .previous\n" \ 211 _ASM_EXTABLE(1b, 3b) \ 212 : "+r" (err), "=&r" (x) \ 213 : "r" (addr), "i" (-EFAULT)) 214 215 #define __get_user_err(x, ptr, err) \ 216 do { \ 217 unsigned long __gu_val; \ 218 __chk_user_ptr(ptr); \ 219 uaccess_enable_not_uao(); \ 220 switch (sizeof(*(ptr))) { \ 221 case 1: \ 222 __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ 223 (err), ARM64_HAS_UAO); \ 224 break; \ 225 case 2: \ 226 __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ 227 (err), ARM64_HAS_UAO); \ 228 break; \ 229 case 4: \ 230 __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ 231 (err), ARM64_HAS_UAO); \ 232 break; \ 233 case 8: \ 234 __get_user_asm("ldr", "ldtr", "%x", __gu_val, (ptr), \ 235 (err), ARM64_HAS_UAO); \ 236 break; \ 237 default: \ 238 BUILD_BUG(); \ 239 } \ 240 uaccess_disable_not_uao(); \ 241 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 242 } while (0) 243 244 #define __get_user(x, ptr) \ 245 ({ \ 246 int __gu_err = 0; \ 247 __get_user_err((x), (ptr), __gu_err); \ 248 __gu_err; \ 249 }) 250 251 #define __get_user_error(x, ptr, err) \ 252 ({ \ 253 __get_user_err((x), (ptr), (err)); \ 254 (void)0; \ 255 }) 256 257 #define get_user(x, ptr) \ 258 ({ \ 259 __typeof__(*(ptr)) __user *__p = (ptr); \ 260 might_fault(); \ 261 access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ 262 __get_user((x), __p) : \ 263 ((x) = 0, -EFAULT); \ 264 }) 265 266 #define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 267 asm volatile( \ 268 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 269 alt_instr " " reg "1, [%2]\n", feature) \ 270 "2:\n" \ 271 " .section .fixup,\"ax\"\n" \ 272 " .align 2\n" \ 273 "3: mov %w0, %3\n" \ 274 " b 2b\n" \ 275 " .previous\n" \ 276 _ASM_EXTABLE(1b, 3b) \ 277 : "+r" (err) \ 278 : "r" (x), "r" (addr), "i" (-EFAULT)) 279 280 #define __put_user_err(x, ptr, err) \ 281 do { \ 282 __typeof__(*(ptr)) __pu_val = (x); \ 283 __chk_user_ptr(ptr); \ 284 uaccess_enable_not_uao(); \ 285 switch (sizeof(*(ptr))) { \ 286 case 1: \ 287 __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ 288 (err), ARM64_HAS_UAO); \ 289 break; \ 290 case 2: \ 291 __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ 292 (err), ARM64_HAS_UAO); \ 293 break; \ 294 case 4: \ 295 __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ 296 (err), ARM64_HAS_UAO); \ 297 break; \ 298 case 8: \ 299 __put_user_asm("str", "sttr", "%x", __pu_val, (ptr), \ 300 (err), ARM64_HAS_UAO); \ 301 break; \ 302 default: \ 303 BUILD_BUG(); \ 304 } \ 305 uaccess_disable_not_uao(); \ 306 } while (0) 307 308 #define __put_user(x, ptr) \ 309 ({ \ 310 int __pu_err = 0; \ 311 __put_user_err((x), (ptr), __pu_err); \ 312 __pu_err; \ 313 }) 314 315 #define __put_user_error(x, ptr, err) \ 316 ({ \ 317 __put_user_err((x), (ptr), (err)); \ 318 (void)0; \ 319 }) 320 321 #define put_user(x, ptr) \ 322 ({ \ 323 __typeof__(*(ptr)) __user *__p = (ptr); \ 324 might_fault(); \ 325 access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ 326 __put_user((x), __p) : \ 327 -EFAULT; \ 328 }) 329 330 extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); 331 #define raw_copy_from_user __arch_copy_from_user 332 extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); 333 #define raw_copy_to_user __arch_copy_to_user 334 extern unsigned long __must_check raw_copy_in_user(void __user *to, const void __user *from, unsigned long n); 335 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 336 #define INLINE_COPY_TO_USER 337 #define INLINE_COPY_FROM_USER 338 339 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 340 { 341 if (access_ok(VERIFY_WRITE, to, n)) 342 n = __clear_user(to, n); 343 return n; 344 } 345 346 extern long strncpy_from_user(char *dest, const char __user *src, long count); 347 348 extern __must_check long strnlen_user(const char __user *str, long n); 349 350 #endif /* __ASM_UACCESS_H */ 351