arch/arm64/include/asm/uaccess.h

   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 */