103 lines
2.1 KiB
C
103 lines
2.1 KiB
C
/* uaccess.c: userspace access functions
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*
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* Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <asm/uaccess.h>
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/*****************************************************************************/
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/*
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* copy a null terminated string from userspace
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*/
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long strncpy_from_user(char *dst, const char __user *src, long count)
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{
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unsigned long max;
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char *p, ch;
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long err = -EFAULT;
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if (count < 0)
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BUG();
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p = dst;
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#ifndef CONFIG_MMU
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if ((unsigned long) src < memory_start)
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goto error;
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#endif
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if ((unsigned long) src >= get_addr_limit())
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goto error;
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max = get_addr_limit() - (unsigned long) src;
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if ((unsigned long) count > max) {
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memset(dst + max, 0, count - max);
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count = max;
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}
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err = 0;
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for (; count > 0; count--, p++, src++) {
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__get_user_asm(err, ch, src, "ub", "=r");
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if (err < 0)
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goto error;
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if (!ch)
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break;
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*p = ch;
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}
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err = p - dst; /* return length excluding NUL */
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error:
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if (count > 0)
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memset(p, 0, count); /* clear remainder of buffer [security] */
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return err;
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} /* end strncpy_from_user() */
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EXPORT_SYMBOL(strncpy_from_user);
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/*****************************************************************************/
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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 *src, long count)
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{
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const char __user *p;
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long err = 0;
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char ch;
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if (count < 0)
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BUG();
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#ifndef CONFIG_MMU
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if ((unsigned long) src < memory_start)
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return 0;
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#endif
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if ((unsigned long) src >= get_addr_limit())
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return 0;
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for (p = src; count > 0; count--, p++) {
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__get_user_asm(err, ch, p, "ub", "=r");
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if (err < 0)
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return 0;
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if (!ch)
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break;
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}
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return p - src + 1; /* return length including NUL */
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} /* end strnlen_user() */
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EXPORT_SYMBOL(strnlen_user);
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