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93 lines
2.2 KiB
93 lines
2.2 KiB
// SPDX-License-Identifier: GPL-2.0 |
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#include <linux/bitops.h> |
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#include <linux/fault-inject-usercopy.h> |
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#include <linux/instrumented.h> |
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#include <linux/uaccess.h> |
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/* out-of-line parts */ |
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#ifndef INLINE_COPY_FROM_USER |
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unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n) |
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{ |
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unsigned long res = n; |
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might_fault(); |
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if (!should_fail_usercopy() && likely(access_ok(from, n))) { |
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instrument_copy_from_user_before(to, from, n); |
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res = raw_copy_from_user(to, from, n); |
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instrument_copy_from_user_after(to, from, n, res); |
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} |
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if (unlikely(res)) |
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memset(to + (n - res), 0, res); |
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return res; |
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} |
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EXPORT_SYMBOL(_copy_from_user); |
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#endif |
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#ifndef INLINE_COPY_TO_USER |
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unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) |
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{ |
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might_fault(); |
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if (should_fail_usercopy()) |
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return n; |
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if (likely(access_ok(to, n))) { |
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instrument_copy_to_user(to, from, n); |
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n = raw_copy_to_user(to, from, n); |
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} |
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return n; |
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} |
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EXPORT_SYMBOL(_copy_to_user); |
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#endif |
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/** |
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* check_zeroed_user: check if a userspace buffer only contains zero bytes |
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* @from: Source address, in userspace. |
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* @size: Size of buffer. |
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* |
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* This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for |
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* userspace addresses (and is more efficient because we don't care where the |
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* first non-zero byte is). |
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* |
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* Returns: |
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* * 0: There were non-zero bytes present in the buffer. |
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* * 1: The buffer was full of zero bytes. |
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* * -EFAULT: access to userspace failed. |
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*/ |
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int check_zeroed_user(const void __user *from, size_t size) |
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{ |
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unsigned long val; |
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uintptr_t align = (uintptr_t) from % sizeof(unsigned long); |
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if (unlikely(size == 0)) |
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return 1; |
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from -= align; |
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size += align; |
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if (!user_read_access_begin(from, size)) |
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return -EFAULT; |
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unsafe_get_user(val, (unsigned long __user *) from, err_fault); |
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if (align) |
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val &= ~aligned_byte_mask(align); |
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while (size > sizeof(unsigned long)) { |
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if (unlikely(val)) |
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goto done; |
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from += sizeof(unsigned long); |
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size -= sizeof(unsigned long); |
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unsafe_get_user(val, (unsigned long __user *) from, err_fault); |
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} |
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if (size < sizeof(unsigned long)) |
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val &= aligned_byte_mask(size); |
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done: |
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user_read_access_end(); |
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return (val == 0); |
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err_fault: |
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user_read_access_end(); |
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return -EFAULT; |
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} |
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EXPORT_SYMBOL(check_zeroed_user);
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