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/kasan-checks.h> 25 #include <linux/string.h> 26 #include <linux/thread_info.h> 27 28 #include <asm/alternative.h> 29 #include <asm/cpufeature.h> 30 #include <asm/ptrace.h> 31 #include <asm/sysreg.h> 32 #include <asm/errno.h> 33 #include <asm/memory.h> 34 #include <asm/compiler.h> 35 36 #define VERIFY_READ 0 37 #define VERIFY_WRITE 1 38 39 /* 40 * The exception table consists of pairs of relative offsets: the first 41 * is the relative offset to an instruction that is allowed to fault, 42 * and the second is the relative offset at which the program should 43 * continue. No registers are modified, so it is entirely up to the 44 * continuation code to figure out what to do. 45 * 46 * All the routines below use bits of fixup code that are out of line 47 * with the main instruction path. This means when everything is well, 48 * we don't even have to jump over them. Further, they do not intrude 49 * on our cache or tlb entries. 50 */ 51 52 struct exception_table_entry 53 { 54 int insn, fixup; 55 }; 56 57 #define ARCH_HAS_RELATIVE_EXTABLE 58 59 extern int fixup_exception(struct pt_regs *regs); 60 61 #define KERNEL_DS (-1UL) 62 #define get_ds() (KERNEL_DS) 63 64 #define USER_DS TASK_SIZE_64 65 #define get_fs() (current_thread_info()->addr_limit) 66 67 static inline void set_fs(mm_segment_t fs) 68 { 69 current_thread_info()->addr_limit = fs; 70 71 /* 72 * Enable/disable UAO so that copy_to_user() etc can access 73 * kernel memory with the unprivileged instructions. 74 */ 75 if (IS_ENABLED(CONFIG_ARM64_UAO) && fs == KERNEL_DS) 76 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO)); 77 else 78 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO, 79 CONFIG_ARM64_UAO)); 80 } 81 82 #define segment_eq(a, b) ((a) == (b)) 83 84 /* 85 * Test whether a block of memory is a valid user space address. 86 * Returns 1 if the range is valid, 0 otherwise. 87 * 88 * This is equivalent to the following test: 89 * (u65)addr + (u65)size <= current->addr_limit 90 * 91 * This needs 65-bit arithmetic. 92 */ 93 #define __range_ok(addr, size) \ 94 ({ \ 95 unsigned long flag, roksum; \ 96 __chk_user_ptr(addr); \ 97 asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ 98 : "=&r" (flag), "=&r" (roksum) \ 99 : "1" (addr), "Ir" (size), \ 100 "r" (current_thread_info()->addr_limit) \ 101 : "cc"); \ 102 flag; \ 103 }) 104 105 #define access_ok(type, addr, size) __range_ok(addr, size) 106 #define user_addr_max get_fs 107 108 #define _ASM_EXTABLE(from, to) \ 109 " .pushsection __ex_table, \"a\"\n" \ 110 " .align 3\n" \ 111 " .long (" #from " - .), (" #to " - .)\n" \ 112 " .popsection\n" 113 114 /* 115 * The "__xxx" versions of the user access functions do not verify the address 116 * space - it must have been done previously with a separate "access_ok()" 117 * call. 118 * 119 * The "__xxx_error" versions set the third argument to -EFAULT if an error 120 * occurs, and leave it unchanged on success. 121 */ 122 #define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 123 asm volatile( \ 124 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 125 alt_instr " " reg "1, [%2]\n", feature) \ 126 "2:\n" \ 127 " .section .fixup, \"ax\"\n" \ 128 " .align 2\n" \ 129 "3: mov %w0, %3\n" \ 130 " mov %1, #0\n" \ 131 " b 2b\n" \ 132 " .previous\n" \ 133 _ASM_EXTABLE(1b, 3b) \ 134 : "+r" (err), "=&r" (x) \ 135 : "r" (addr), "i" (-EFAULT)) 136 137 #define __get_user_err(x, ptr, err) \ 138 do { \ 139 unsigned long __gu_val; \ 140 __chk_user_ptr(ptr); \ 141 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ 142 CONFIG_ARM64_PAN)); \ 143 switch (sizeof(*(ptr))) { \ 144 case 1: \ 145 __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ 146 (err), ARM64_HAS_UAO); \ 147 break; \ 148 case 2: \ 149 __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ 150 (err), ARM64_HAS_UAO); \ 151 break; \ 152 case 4: \ 153 __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ 154 (err), ARM64_HAS_UAO); \ 155 break; \ 156 case 8: \ 157 __get_user_asm("ldr", "ldtr", "%", __gu_val, (ptr), \ 158 (err), ARM64_HAS_UAO); \ 159 break; \ 160 default: \ 161 BUILD_BUG(); \ 162 } \ 163 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 164 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ 165 CONFIG_ARM64_PAN)); \ 166 } while (0) 167 168 #define __get_user(x, ptr) \ 169 ({ \ 170 int __gu_err = 0; \ 171 __get_user_err((x), (ptr), __gu_err); \ 172 __gu_err; \ 173 }) 174 175 #define __get_user_error(x, ptr, err) \ 176 ({ \ 177 __get_user_err((x), (ptr), (err)); \ 178 (void)0; \ 179 }) 180 181 #define __get_user_unaligned __get_user 182 183 #define get_user(x, ptr) \ 184 ({ \ 185 __typeof__(*(ptr)) __user *__p = (ptr); \ 186 might_fault(); \ 187 access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ 188 __get_user((x), __p) : \ 189 ((x) = 0, -EFAULT); \ 190 }) 191 192 #define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 193 asm volatile( \ 194 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 195 alt_instr " " reg "1, [%2]\n", feature) \ 196 "2:\n" \ 197 " .section .fixup,\"ax\"\n" \ 198 " .align 2\n" \ 199 "3: mov %w0, %3\n" \ 200 " b 2b\n" \ 201 " .previous\n" \ 202 _ASM_EXTABLE(1b, 3b) \ 203 : "+r" (err) \ 204 : "r" (x), "r" (addr), "i" (-EFAULT)) 205 206 #define __put_user_err(x, ptr, err) \ 207 do { \ 208 __typeof__(*(ptr)) __pu_val = (x); \ 209 __chk_user_ptr(ptr); \ 210 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ 211 CONFIG_ARM64_PAN)); \ 212 switch (sizeof(*(ptr))) { \ 213 case 1: \ 214 __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ 215 (err), ARM64_HAS_UAO); \ 216 break; \ 217 case 2: \ 218 __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ 219 (err), ARM64_HAS_UAO); \ 220 break; \ 221 case 4: \ 222 __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ 223 (err), ARM64_HAS_UAO); \ 224 break; \ 225 case 8: \ 226 __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ 227 (err), ARM64_HAS_UAO); \ 228 break; \ 229 default: \ 230 BUILD_BUG(); \ 231 } \ 232 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ 233 CONFIG_ARM64_PAN)); \ 234 } while (0) 235 236 #define __put_user(x, ptr) \ 237 ({ \ 238 int __pu_err = 0; \ 239 __put_user_err((x), (ptr), __pu_err); \ 240 __pu_err; \ 241 }) 242 243 #define __put_user_error(x, ptr, err) \ 244 ({ \ 245 __put_user_err((x), (ptr), (err)); \ 246 (void)0; \ 247 }) 248 249 #define __put_user_unaligned __put_user 250 251 #define put_user(x, ptr) \ 252 ({ \ 253 __typeof__(*(ptr)) __user *__p = (ptr); \ 254 might_fault(); \ 255 access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ 256 __put_user((x), __p) : \ 257 -EFAULT; \ 258 }) 259 260 extern unsigned long __must_check __arch_copy_from_user(void *to, const void __user *from, unsigned long n); 261 extern unsigned long __must_check __arch_copy_to_user(void __user *to, const void *from, unsigned long n); 262 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n); 263 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 264 265 static inline unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n) 266 { 267 kasan_check_write(to, n); 268 check_object_size(to, n, false); 269 return __arch_copy_from_user(to, from, n); 270 } 271 272 static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n) 273 { 274 kasan_check_read(from, n); 275 check_object_size(from, n, true); 276 return __arch_copy_to_user(to, from, n); 277 } 278 279 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) 280 { 281 kasan_check_write(to, n); 282 283 if (access_ok(VERIFY_READ, from, n)) { 284 check_object_size(to, n, false); 285 n = __arch_copy_from_user(to, from, n); 286 } else /* security hole - plug it */ 287 memset(to, 0, n); 288 return n; 289 } 290 291 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) 292 { 293 kasan_check_read(from, n); 294 295 if (access_ok(VERIFY_WRITE, to, n)) { 296 check_object_size(from, n, true); 297 n = __arch_copy_to_user(to, from, n); 298 } 299 return n; 300 } 301 302 static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n) 303 { 304 if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n)) 305 n = __copy_in_user(to, from, n); 306 return n; 307 } 308 309 #define __copy_to_user_inatomic __copy_to_user 310 #define __copy_from_user_inatomic __copy_from_user 311 312 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 313 { 314 if (access_ok(VERIFY_WRITE, to, n)) 315 n = __clear_user(to, n); 316 return n; 317 } 318 319 extern long strncpy_from_user(char *dest, const char __user *src, long count); 320 321 extern __must_check long strlen_user(const char __user *str); 322 extern __must_check long strnlen_user(const char __user *str, long n); 323 324 #endif /* __ASM_UACCESS_H */ 325