1 /* 2 * User address space access functions. 3 * 4 * Copyright 1997 Andi Kleen <ak@muc.de> 5 * Copyright 1997 Linus Torvalds 6 * Copyright 2002 Andi Kleen <ak@suse.de> 7 */ 8 #include <linux/module.h> 9 #include <asm/uaccess.h> 10 11 /* 12 * Copy a null terminated string from userspace. 13 */ 14 15 #define __do_strncpy_from_user(dst,src,count,res) \ 16 do { \ 17 long __d0, __d1, __d2; \ 18 might_fault(); \ 19 __asm__ __volatile__( \ 20 " testq %1,%1\n" \ 21 " jz 2f\n" \ 22 "0: lodsb\n" \ 23 " stosb\n" \ 24 " testb %%al,%%al\n" \ 25 " jz 1f\n" \ 26 " decq %1\n" \ 27 " jnz 0b\n" \ 28 "1: subq %1,%0\n" \ 29 "2:\n" \ 30 ".section .fixup,\"ax\"\n" \ 31 "3: movq %5,%0\n" \ 32 " jmp 2b\n" \ 33 ".previous\n" \ 34 _ASM_EXTABLE(0b,3b) \ 35 : "=&r"(res), "=&c"(count), "=&a" (__d0), "=&S" (__d1), \ 36 "=&D" (__d2) \ 37 : "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \ 38 : "memory"); \ 39 } while (0) 40 41 long 42 __strncpy_from_user(char *dst, const char __user *src, long count) 43 { 44 long res; 45 __do_strncpy_from_user(dst, src, count, res); 46 return res; 47 } 48 EXPORT_SYMBOL(__strncpy_from_user); 49 50 long 51 strncpy_from_user(char *dst, const char __user *src, long count) 52 { 53 long res = -EFAULT; 54 if (access_ok(VERIFY_READ, src, 1)) 55 return __strncpy_from_user(dst, src, count); 56 return res; 57 } 58 EXPORT_SYMBOL(strncpy_from_user); 59 60 /* 61 * Zero Userspace 62 */ 63 64 unsigned long __clear_user(void __user *addr, unsigned long size) 65 { 66 long __d0; 67 might_fault(); 68 /* no memory constraint because it doesn't change any memory gcc knows 69 about */ 70 asm volatile( 71 " testq %[size8],%[size8]\n" 72 " jz 4f\n" 73 "0: movq %[zero],(%[dst])\n" 74 " addq %[eight],%[dst]\n" 75 " decl %%ecx ; jnz 0b\n" 76 "4: movq %[size1],%%rcx\n" 77 " testl %%ecx,%%ecx\n" 78 " jz 2f\n" 79 "1: movb %b[zero],(%[dst])\n" 80 " incq %[dst]\n" 81 " decl %%ecx ; jnz 1b\n" 82 "2:\n" 83 ".section .fixup,\"ax\"\n" 84 "3: lea 0(%[size1],%[size8],8),%[size8]\n" 85 " jmp 2b\n" 86 ".previous\n" 87 _ASM_EXTABLE(0b,3b) 88 _ASM_EXTABLE(1b,2b) 89 : [size8] "=&c"(size), [dst] "=&D" (__d0) 90 : [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr), 91 [zero] "r" (0UL), [eight] "r" (8UL)); 92 return size; 93 } 94 EXPORT_SYMBOL(__clear_user); 95 96 unsigned long clear_user(void __user *to, unsigned long n) 97 { 98 if (access_ok(VERIFY_WRITE, to, n)) 99 return __clear_user(to, n); 100 return n; 101 } 102 EXPORT_SYMBOL(clear_user); 103 104 /* 105 * Return the size of a string (including the ending 0) 106 * 107 * Return 0 on exception, a value greater than N if too long 108 */ 109 110 long __strnlen_user(const char __user *s, long n) 111 { 112 long res = 0; 113 char c; 114 115 while (1) { 116 if (res>n) 117 return n+1; 118 if (__get_user(c, s)) 119 return 0; 120 if (!c) 121 return res+1; 122 res++; 123 s++; 124 } 125 } 126 EXPORT_SYMBOL(__strnlen_user); 127 128 long strnlen_user(const char __user *s, long n) 129 { 130 if (!access_ok(VERIFY_READ, s, 1)) 131 return 0; 132 return __strnlen_user(s, n); 133 } 134 EXPORT_SYMBOL(strnlen_user); 135 136 long strlen_user(const char __user *s) 137 { 138 long res = 0; 139 char c; 140 141 for (;;) { 142 if (get_user(c, s)) 143 return 0; 144 if (!c) 145 return res+1; 146 res++; 147 s++; 148 } 149 } 150 EXPORT_SYMBOL(strlen_user); 151 152 unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len) 153 { 154 if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) { 155 return copy_user_generic((__force void *)to, (__force void *)from, len); 156 } 157 return len; 158 } 159 EXPORT_SYMBOL(copy_in_user); 160 161 /* 162 * Try to copy last bytes and clear the rest if needed. 163 * Since protection fault in copy_from/to_user is not a normal situation, 164 * it is not necessary to optimize tail handling. 165 */ 166 unsigned long 167 copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest) 168 { 169 char c; 170 unsigned zero_len; 171 172 for (; len; --len) { 173 if (__get_user_nocheck(c, from++, sizeof(char))) 174 break; 175 if (__put_user_nocheck(c, to++, sizeof(char))) 176 break; 177 } 178 179 for (c = 0, zero_len = len; zerorest && zero_len; --zero_len) 180 if (__put_user_nocheck(c, to++, sizeof(char))) 181 break; 182 return len; 183 } 184