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 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 */