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