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