184 строки
4.0 KiB
C
184 строки
4.0 KiB
C
/*
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* User address space access functions.
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*
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* Copyright 1997 Andi Kleen <ak@muc.de>
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* Copyright 1997 Linus Torvalds
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* Copyright 2002 Andi Kleen <ak@suse.de>
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*/
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#include <linux/module.h>
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#include <asm/uaccess.h>
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/*
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* Copy a null terminated string from userspace.
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*/
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#define __do_strncpy_from_user(dst,src,count,res) \
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do { \
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long __d0, __d1, __d2; \
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might_fault(); \
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__asm__ __volatile__( \
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" testq %1,%1\n" \
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" jz 2f\n" \
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"0: lodsb\n" \
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" stosb\n" \
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" testb %%al,%%al\n" \
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" jz 1f\n" \
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" decq %1\n" \
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" jnz 0b\n" \
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"1: subq %1,%0\n" \
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"2:\n" \
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".section .fixup,\"ax\"\n" \
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"3: movq %5,%0\n" \
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" jmp 2b\n" \
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".previous\n" \
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_ASM_EXTABLE(0b,3b) \
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: "=&r"(res), "=&c"(count), "=&a" (__d0), "=&S" (__d1), \
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"=&D" (__d2) \
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: "i"(-EFAULT), "0"(count), "1"(count), "3"(src), "4"(dst) \
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: "memory"); \
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} while (0)
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long
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__strncpy_from_user(char *dst, const char __user *src, long count)
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{
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long res;
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__do_strncpy_from_user(dst, src, count, res);
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return res;
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}
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EXPORT_SYMBOL(__strncpy_from_user);
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long
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strncpy_from_user(char *dst, const char __user *src, long count)
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{
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long res = -EFAULT;
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if (access_ok(VERIFY_READ, src, 1))
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return __strncpy_from_user(dst, src, count);
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return res;
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}
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EXPORT_SYMBOL(strncpy_from_user);
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/*
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* Zero Userspace
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*/
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unsigned long __clear_user(void __user *addr, unsigned long size)
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{
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long __d0;
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might_fault();
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/* no memory constraint because it doesn't change any memory gcc knows
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about */
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asm volatile(
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" testq %[size8],%[size8]\n"
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" jz 4f\n"
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"0: movq %[zero],(%[dst])\n"
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" addq %[eight],%[dst]\n"
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" decl %%ecx ; jnz 0b\n"
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"4: movq %[size1],%%rcx\n"
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" testl %%ecx,%%ecx\n"
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" jz 2f\n"
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"1: movb %b[zero],(%[dst])\n"
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" incq %[dst]\n"
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" decl %%ecx ; jnz 1b\n"
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"2:\n"
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".section .fixup,\"ax\"\n"
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"3: lea 0(%[size1],%[size8],8),%[size8]\n"
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" jmp 2b\n"
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".previous\n"
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_ASM_EXTABLE(0b,3b)
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_ASM_EXTABLE(1b,2b)
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: [size8] "=&c"(size), [dst] "=&D" (__d0)
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: [size1] "r"(size & 7), "[size8]" (size / 8), "[dst]"(addr),
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[zero] "r" (0UL), [eight] "r" (8UL));
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return size;
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}
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EXPORT_SYMBOL(__clear_user);
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unsigned long clear_user(void __user *to, unsigned long n)
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{
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if (access_ok(VERIFY_WRITE, to, n))
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return __clear_user(to, n);
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return n;
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}
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EXPORT_SYMBOL(clear_user);
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/*
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* Return the size of a string (including the ending 0)
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*
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* Return 0 on exception, a value greater than N if too long
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*/
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long __strnlen_user(const char __user *s, long n)
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{
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long res = 0;
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char c;
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while (1) {
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if (res>n)
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return n+1;
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if (__get_user(c, s))
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return 0;
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if (!c)
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return res+1;
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res++;
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s++;
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}
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}
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EXPORT_SYMBOL(__strnlen_user);
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long strnlen_user(const char __user *s, long n)
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{
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if (!access_ok(VERIFY_READ, s, 1))
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return 0;
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return __strnlen_user(s, n);
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}
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EXPORT_SYMBOL(strnlen_user);
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long strlen_user(const char __user *s)
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{
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long res = 0;
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char c;
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for (;;) {
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if (get_user(c, s))
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return 0;
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if (!c)
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return res+1;
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res++;
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s++;
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}
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}
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EXPORT_SYMBOL(strlen_user);
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unsigned long copy_in_user(void __user *to, const void __user *from, unsigned len)
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{
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if (access_ok(VERIFY_WRITE, to, len) && access_ok(VERIFY_READ, from, len)) {
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return copy_user_generic((__force void *)to, (__force void *)from, len);
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}
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return len;
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}
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EXPORT_SYMBOL(copy_in_user);
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/*
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* Try to copy last bytes and clear the rest if needed.
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* Since protection fault in copy_from/to_user is not a normal situation,
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* it is not necessary to optimize tail handling.
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*/
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unsigned long
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copy_user_handle_tail(char *to, char *from, unsigned len, unsigned zerorest)
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{
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char c;
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unsigned zero_len;
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for (; len; --len) {
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if (__get_user_nocheck(c, from++, sizeof(char)))
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break;
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if (__put_user_nocheck(c, to++, sizeof(char)))
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break;
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}
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for (c = 0, zero_len = len; zerorest && zero_len; --zero_len)
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if (__put_user_nocheck(c, to++, sizeof(char)))
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break;
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return len;
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}
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