cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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usercopy.c (2239B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <linux/bitops.h>
      3#include <linux/fault-inject-usercopy.h>
      4#include <linux/instrumented.h>
      5#include <linux/uaccess.h>
      6
      7/* out-of-line parts */
      8
      9#ifndef INLINE_COPY_FROM_USER
     10unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
     11{
     12	unsigned long res = n;
     13	might_fault();
     14	if (!should_fail_usercopy() && likely(access_ok(from, n))) {
     15		instrument_copy_from_user(to, from, n);
     16		res = raw_copy_from_user(to, from, n);
     17	}
     18	if (unlikely(res))
     19		memset(to + (n - res), 0, res);
     20	return res;
     21}
     22EXPORT_SYMBOL(_copy_from_user);
     23#endif
     24
     25#ifndef INLINE_COPY_TO_USER
     26unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)
     27{
     28	might_fault();
     29	if (should_fail_usercopy())
     30		return n;
     31	if (likely(access_ok(to, n))) {
     32		instrument_copy_to_user(to, from, n);
     33		n = raw_copy_to_user(to, from, n);
     34	}
     35	return n;
     36}
     37EXPORT_SYMBOL(_copy_to_user);
     38#endif
     39
     40/**
     41 * check_zeroed_user: check if a userspace buffer only contains zero bytes
     42 * @from: Source address, in userspace.
     43 * @size: Size of buffer.
     44 *
     45 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
     46 * userspace addresses (and is more efficient because we don't care where the
     47 * first non-zero byte is).
     48 *
     49 * Returns:
     50 *  * 0: There were non-zero bytes present in the buffer.
     51 *  * 1: The buffer was full of zero bytes.
     52 *  * -EFAULT: access to userspace failed.
     53 */
     54int check_zeroed_user(const void __user *from, size_t size)
     55{
     56	unsigned long val;
     57	uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
     58
     59	if (unlikely(size == 0))
     60		return 1;
     61
     62	from -= align;
     63	size += align;
     64
     65	if (!user_read_access_begin(from, size))
     66		return -EFAULT;
     67
     68	unsafe_get_user(val, (unsigned long __user *) from, err_fault);
     69	if (align)
     70		val &= ~aligned_byte_mask(align);
     71
     72	while (size > sizeof(unsigned long)) {
     73		if (unlikely(val))
     74			goto done;
     75
     76		from += sizeof(unsigned long);
     77		size -= sizeof(unsigned long);
     78
     79		unsafe_get_user(val, (unsigned long __user *) from, err_fault);
     80	}
     81
     82	if (size < sizeof(unsigned long))
     83		val &= aligned_byte_mask(size);
     84
     85done:
     86	user_read_access_end();
     87	return (val == 0);
     88err_fault:
     89	user_read_access_end();
     90	return -EFAULT;
     91}
     92EXPORT_SYMBOL(check_zeroed_user);