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 /* 22 * User space memory access functions 23 */ 24 #include <linux/bitops.h> 25 #include <linux/kasan-checks.h> 26 #include <linux/string.h> 27 #include <linux/thread_info.h> 28 29 #include <asm/alternative.h> 30 #include <asm/cpufeature.h> 31 #include <asm/ptrace.h> 32 #include <asm/sysreg.h> 33 #include <asm/errno.h> 34 #include <asm/memory.h> 35 #include <asm/compiler.h> 36 37 #define VERIFY_READ 0 38 #define VERIFY_WRITE 1 39 40 /* 41 * The exception table consists of pairs of relative offsets: the first 42 * is the relative offset to an instruction that is allowed to fault, 43 * and the second is the relative offset at which the program should 44 * continue. No registers are modified, so it is entirely up to the 45 * continuation code to figure out what to do. 46 * 47 * All the routines below use bits of fixup code that are out of line 48 * with the main instruction path. This means when everything is well, 49 * we don't even have to jump over them. Further, they do not intrude 50 * on our cache or tlb entries. 51 */ 52 53 struct exception_table_entry 54 { 55 int insn, fixup; 56 }; 57 58 #define ARCH_HAS_RELATIVE_EXTABLE 59 60 extern int fixup_exception(struct pt_regs *regs); 61 62 #define KERNEL_DS (-1UL) 63 #define get_ds() (KERNEL_DS) 64 65 #define USER_DS TASK_SIZE_64 66 #define get_fs() (current_thread_info()->addr_limit) 67 68 static inline void set_fs(mm_segment_t fs) 69 { 70 current_thread_info()->addr_limit = fs; 71 72 /* 73 * Enable/disable UAO so that copy_to_user() etc can access 74 * kernel memory with the unprivileged instructions. 75 */ 76 if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS) 77 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO)); 78 else 79 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO, 80 CONFIG_ARM64_UAO)); 81 } 82 83 #define segment_eq(a, b) ((a) == (b)) 84 85 /* 86 * Test whether a block of memory is a valid user space address. 87 * Returns 1 if the range is valid, 0 otherwise. 88 * 89 * This is equivalent to the following test: 90 * (u65)addr + (u65)size <= current->addr_limit 91 * 92 * This needs 65-bit arithmetic. 93 */ 94 #define __range_ok(addr, size) \ 95 ({ \ 96 unsigned long flag, roksum; \ 97 __chk_user_ptr(addr); \ 98 asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ 99 : "=&r" (flag), "=&r" (roksum) \ 100 : "1" (addr), "Ir" (size), \ 101 "r" (current_thread_info()->addr_limit) \ 102 : "cc"); \ 103 flag; \ 104 }) 105 106 /* 107 * When dealing with data aborts or instruction traps we may end up with 108 * a tagged userland pointer. Clear the tag to get a sane pointer to pass 109 * on to access_ok(), for instance. 110 */ 111 #define untagged_addr(addr) sign_extend64(addr, 55) 112 113 #define access_ok(type, addr, size) __range_ok(addr, size) 114 #define user_addr_max get_fs 115 116 #define _ASM_EXTABLE(from, to) \ 117 " .pushsection __ex_table, \"a\"\n" \ 118 " .align 3\n" \ 119 " .long (" #from " - .), (" #to " - .)\n" \ 120 " .popsection\n" 121 122 /* 123 * The "__xxx" versions of the user access functions do not verify the address 124 * space - it must have been done previously with a separate "access_ok()" 125 * call. 126 * 127 * The "__xxx_error" versions set the third argument to -EFAULT if an error 128 * occurs, and leave it unchanged on success. 129 */ 130 #define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 131 asm volatile( \ 132 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 133 alt_instr " " reg "1, [%2]\n", feature) \ 134 "2:\n" \ 135 " .section .fixup, \"ax\"\n" \ 136 " .align 2\n" \ 137 "3: mov %w0, %3\n" \ 138 " mov %1, #0\n" \ 139 " b 2b\n" \ 140 " .previous\n" \ 141 _ASM_EXTABLE(1b, 3b) \ 142 : "+r" (err), "=&r" (x) \ 143 : "r" (addr), "i" (-EFAULT)) 144 145 #define __get_user_err(x, ptr, err) \ 146 do { \ 147 unsigned long __gu_val; \ 148 __chk_user_ptr(ptr); \ 149 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ 150 CONFIG_ARM64_PAN)); \ 151 switch (sizeof(*(ptr))) { \ 152 case 1: \ 153 __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ 154 (err), ARM64_HAS_UAO); \ 155 break; \ 156 case 2: \ 157 __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ 158 (err), ARM64_HAS_UAO); \ 159 break; \ 160 case 4: \ 161 __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ 162 (err), ARM64_HAS_UAO); \ 163 break; \ 164 case 8: \ 165 __get_user_asm("ldr", "ldtr", "%", __gu_val, (ptr), \ 166 (err), ARM64_HAS_UAO); \ 167 break; \ 168 default: \ 169 BUILD_BUG(); \ 170 } \ 171 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 172 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ 173 CONFIG_ARM64_PAN)); \ 174 } while (0) 175 176 #define __get_user(x, ptr) \ 177 ({ \ 178 int __gu_err = 0; \ 179 __get_user_err((x), (ptr), __gu_err); \ 180 __gu_err; \ 181 }) 182 183 #define __get_user_error(x, ptr, err) \ 184 ({ \ 185 __get_user_err((x), (ptr), (err)); \ 186 (void)0; \ 187 }) 188 189 #define __get_user_unaligned __get_user 190 191 #define get_user(x, ptr) \ 192 ({ \ 193 __typeof__(*(ptr)) __user *__p = (ptr); \ 194 might_fault(); \ 195 access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ 196 __get_user((x), __p) : \ 197 ((x) = 0, -EFAULT); \ 198 }) 199 200 #define __put_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 " b 2b\n" \ 209 " .previous\n" \ 210 _ASM_EXTABLE(1b, 3b) \ 211 : "+r" (err) \ 212 : "r" (x), "r" (addr), "i" (-EFAULT)) 213 214 #define __put_user_err(x, ptr, err) \ 215 do { \ 216 __typeof__(*(ptr)) __pu_val = (x); \ 217 __chk_user_ptr(ptr); \ 218 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ 219 CONFIG_ARM64_PAN)); \ 220 switch (sizeof(*(ptr))) { \ 221 case 1: \ 222 __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ 223 (err), ARM64_HAS_UAO); \ 224 break; \ 225 case 2: \ 226 __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ 227 (err), ARM64_HAS_UAO); \ 228 break; \ 229 case 4: \ 230 __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ 231 (err), ARM64_HAS_UAO); \ 232 break; \ 233 case 8: \ 234 __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ 235 (err), ARM64_HAS_UAO); \ 236 break; \ 237 default: \ 238 BUILD_BUG(); \ 239 } \ 240 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ 241 CONFIG_ARM64_PAN)); \ 242 } while (0) 243 244 #define __put_user(x, ptr) \ 245 ({ \ 246 int __pu_err = 0; \ 247 __put_user_err((x), (ptr), __pu_err); \ 248 __pu_err; \ 249 }) 250 251 #define __put_user_error(x, ptr, err) \ 252 ({ \ 253 __put_user_err((x), (ptr), (err)); \ 254 (void)0; \ 255 }) 256 257 #define __put_user_unaligned __put_user 258 259 #define put_user(x, ptr) \ 260 ({ \ 261 __typeof__(*(ptr)) __user *__p = (ptr); \ 262 might_fault(); \ 263 access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ 264 __put_user((x), __p) : \ 265 -EFAULT; \ 266 }) 267 268 extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); 269 extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); 270 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n); 271 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 272 273 static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n) 274 { 275 kasan_check_write(to, n); 276 check_object_size(to, n, false); 277 return __arch_copy_from_user(to, from, n); 278 } 279 280 static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n) 281 { 282 kasan_check_read(from, n); 283 check_object_size(from, n, true); 284 return __arch_copy_to_user(to, from, n); 285 } 286 287 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) 288 { 289 unsigned long res = n; 290 kasan_check_write(to, n); 291 292 if (access_ok(VERIFY_READ, from, n)) { 293 check_object_size(to, n, false); 294 res = __arch_copy_from_user(to, from, n); 295 } 296 if (unlikely(res)) 297 memset(to + (n - res), 0, res); 298 return res; 299 } 300 301 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) 302 { 303 kasan_check_read(from, n); 304 305 if (access_ok(VERIFY_WRITE, to, n)) { 306 check_object_size(from, n, true); 307 n = __arch_copy_to_user(to, from, n); 308 } 309 return n; 310 } 311 312 static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n) 313 { 314 if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n)) 315 n = __copy_in_user(to, from, n); 316 return n; 317 } 318 319 #define __copy_to_user_inatomic __copy_to_user 320 #define __copy_from_user_inatomic __copy_from_user 321 322 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 323 { 324 if (access_ok(VERIFY_WRITE, to, n)) 325 n = __clear_user(to, n); 326 return n; 327 } 328 329 extern long strncpy_from_user(char *dest, const char __user *src, long count); 330 331 extern __must_check long strlen_user(const char __user *str); 332 extern __must_check long strnlen_user(const char __user *str, long n); 333 334 #endif /* __ASM_UACCESS_H */ 335