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 * Return 1 if addr < current->addr_limit, 0 otherwise. 85 */ 86 #define __addr_ok(addr) \ 87 ({ \ 88 unsigned long flag; \ 89 asm("cmp %1, %0; cset %0, lo" \ 90 : "=&r" (flag) \ 91 : "r" (addr), "0" (current_thread_info()->addr_limit) \ 92 : "cc"); \ 93 flag; \ 94 }) 95 96 /* 97 * Test whether a block of memory is a valid user space address. 98 * Returns 1 if the range is valid, 0 otherwise. 99 * 100 * This is equivalent to the following test: 101 * (u65)addr + (u65)size <= current->addr_limit 102 * 103 * This needs 65-bit arithmetic. 104 */ 105 #define __range_ok(addr, size) \ 106 ({ \ 107 unsigned long flag, roksum; \ 108 __chk_user_ptr(addr); \ 109 asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ 110 : "=&r" (flag), "=&r" (roksum) \ 111 : "1" (addr), "Ir" (size), \ 112 "r" (current_thread_info()->addr_limit) \ 113 : "cc"); \ 114 flag; \ 115 }) 116 117 #define access_ok(type, addr, size) __range_ok(addr, size) 118 #define user_addr_max get_fs 119 120 #define _ASM_EXTABLE(from, to) \ 121 " .pushsection __ex_table, \"a\"\n" \ 122 " .align 3\n" \ 123 " .long (" #from " - .), (" #to " - .)\n" \ 124 " .popsection\n" 125 126 /* 127 * The "__xxx" versions of the user access functions do not verify the address 128 * space - it must have been done previously with a separate "access_ok()" 129 * call. 130 * 131 * The "__xxx_error" versions set the third argument to -EFAULT if an error 132 * occurs, and leave it unchanged on success. 133 */ 134 #define __get_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 135 asm volatile( \ 136 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 137 alt_instr " " reg "1, [%2]\n", feature) \ 138 "2:\n" \ 139 " .section .fixup, \"ax\"\n" \ 140 " .align 2\n" \ 141 "3: mov %w0, %3\n" \ 142 " mov %1, #0\n" \ 143 " b 2b\n" \ 144 " .previous\n" \ 145 _ASM_EXTABLE(1b, 3b) \ 146 : "+r" (err), "=&r" (x) \ 147 : "r" (addr), "i" (-EFAULT)) 148 149 #define __get_user_err(x, ptr, err) \ 150 do { \ 151 unsigned long __gu_val; \ 152 __chk_user_ptr(ptr); \ 153 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ 154 CONFIG_ARM64_PAN)); \ 155 switch (sizeof(*(ptr))) { \ 156 case 1: \ 157 __get_user_asm("ldrb", "ldtrb", "%w", __gu_val, (ptr), \ 158 (err), ARM64_HAS_UAO); \ 159 break; \ 160 case 2: \ 161 __get_user_asm("ldrh", "ldtrh", "%w", __gu_val, (ptr), \ 162 (err), ARM64_HAS_UAO); \ 163 break; \ 164 case 4: \ 165 __get_user_asm("ldr", "ldtr", "%w", __gu_val, (ptr), \ 166 (err), ARM64_HAS_UAO); \ 167 break; \ 168 case 8: \ 169 __get_user_asm("ldr", "ldtr", "%", __gu_val, (ptr), \ 170 (err), ARM64_HAS_UAO); \ 171 break; \ 172 default: \ 173 BUILD_BUG(); \ 174 } \ 175 (x) = (__force __typeof__(*(ptr)))__gu_val; \ 176 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ 177 CONFIG_ARM64_PAN)); \ 178 } while (0) 179 180 #define __get_user(x, ptr) \ 181 ({ \ 182 int __gu_err = 0; \ 183 __get_user_err((x), (ptr), __gu_err); \ 184 __gu_err; \ 185 }) 186 187 #define __get_user_error(x, ptr, err) \ 188 ({ \ 189 __get_user_err((x), (ptr), (err)); \ 190 (void)0; \ 191 }) 192 193 #define __get_user_unaligned __get_user 194 195 #define get_user(x, ptr) \ 196 ({ \ 197 __typeof__(*(ptr)) __user *__p = (ptr); \ 198 might_fault(); \ 199 access_ok(VERIFY_READ, __p, sizeof(*__p)) ? \ 200 __get_user((x), __p) : \ 201 ((x) = 0, -EFAULT); \ 202 }) 203 204 #define __put_user_asm(instr, alt_instr, reg, x, addr, err, feature) \ 205 asm volatile( \ 206 "1:"ALTERNATIVE(instr " " reg "1, [%2]\n", \ 207 alt_instr " " reg "1, [%2]\n", feature) \ 208 "2:\n" \ 209 " .section .fixup,\"ax\"\n" \ 210 " .align 2\n" \ 211 "3: mov %w0, %3\n" \ 212 " b 2b\n" \ 213 " .previous\n" \ 214 _ASM_EXTABLE(1b, 3b) \ 215 : "+r" (err) \ 216 : "r" (x), "r" (addr), "i" (-EFAULT)) 217 218 #define __put_user_err(x, ptr, err) \ 219 do { \ 220 __typeof__(*(ptr)) __pu_val = (x); \ 221 __chk_user_ptr(ptr); \ 222 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_ALT_PAN_NOT_UAO,\ 223 CONFIG_ARM64_PAN)); \ 224 switch (sizeof(*(ptr))) { \ 225 case 1: \ 226 __put_user_asm("strb", "sttrb", "%w", __pu_val, (ptr), \ 227 (err), ARM64_HAS_UAO); \ 228 break; \ 229 case 2: \ 230 __put_user_asm("strh", "sttrh", "%w", __pu_val, (ptr), \ 231 (err), ARM64_HAS_UAO); \ 232 break; \ 233 case 4: \ 234 __put_user_asm("str", "sttr", "%w", __pu_val, (ptr), \ 235 (err), ARM64_HAS_UAO); \ 236 break; \ 237 case 8: \ 238 __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ 239 (err), ARM64_HAS_UAO); \ 240 break; \ 241 default: \ 242 BUILD_BUG(); \ 243 } \ 244 asm(ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_ALT_PAN_NOT_UAO,\ 245 CONFIG_ARM64_PAN)); \ 246 } while (0) 247 248 #define __put_user(x, ptr) \ 249 ({ \ 250 int __pu_err = 0; \ 251 __put_user_err((x), (ptr), __pu_err); \ 252 __pu_err; \ 253 }) 254 255 #define __put_user_error(x, ptr, err) \ 256 ({ \ 257 __put_user_err((x), (ptr), (err)); \ 258 (void)0; \ 259 }) 260 261 #define __put_user_unaligned __put_user 262 263 #define put_user(x, ptr) \ 264 ({ \ 265 __typeof__(*(ptr)) __user *__p = (ptr); \ 266 might_fault(); \ 267 access_ok(VERIFY_WRITE, __p, sizeof(*__p)) ? \ 268 __put_user((x), __p) : \ 269 -EFAULT; \ 270 }) 271 272 extern unsigned long __must_check __copy_from_user(void *to, const void __user *from, unsigned long n); 273 extern unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n); 274 extern unsigned long __must_check __copy_in_user(void __user *to, const void __user *from, unsigned long n); 275 extern unsigned long __must_check __clear_user(void __user *addr, unsigned long n); 276 277 static inline unsigned long __must_check copy_from_user(void *to, const void __user *from, unsigned long n) 278 { 279 if (access_ok(VERIFY_READ, from, n)) 280 n = __copy_from_user(to, from, n); 281 else /* security hole - plug it */ 282 memset(to, 0, n); 283 return n; 284 } 285 286 static inline unsigned long __must_check copy_to_user(void __user *to, const void *from, unsigned long n) 287 { 288 if (access_ok(VERIFY_WRITE, to, n)) 289 n = __copy_to_user(to, from, n); 290 return n; 291 } 292 293 static inline unsigned long __must_check copy_in_user(void __user *to, const void __user *from, unsigned long n) 294 { 295 if (access_ok(VERIFY_READ, from, n) && access_ok(VERIFY_WRITE, to, n)) 296 n = __copy_in_user(to, from, n); 297 return n; 298 } 299 300 #define __copy_to_user_inatomic __copy_to_user 301 #define __copy_from_user_inatomic __copy_from_user 302 303 static inline unsigned long __must_check clear_user(void __user *to, unsigned long n) 304 { 305 if (access_ok(VERIFY_WRITE, to, n)) 306 n = __clear_user(to, n); 307 return n; 308 } 309 310 extern long strncpy_from_user(char *dest, const char __user *src, long count); 311 312 extern __must_check long strlen_user(const char __user *str); 313 extern __must_check long strnlen_user(const char __user *str, long n); 314 315 #endif /* __ASM_UACCESS_H */ 316