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