| 1 | |
| 2 | #include <linux/bitops.h>
|
| 3 | #include <linux/fault-inject-usercopy.h>
|
| 4 | #include <linux/instrumented.h>
|
| 5 | #include <linux/uaccess.h>
|
| 6 |
|
| 7 |
|
| 8 |
|
| 9 | #ifndef INLINE_COPY_FROM_USER
|
| 10 | unsigned 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 | }
|
| 22 | EXPORT_SYMBOL(_copy_from_user);
|
| 23 | #endif
|
| 24 |
|
| 25 | #ifndef INLINE_COPY_TO_USER
|
| 26 | unsigned 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 | }
|
| 37 | EXPORT_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 |
|
| 54 | int 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 |
|
| 85 | done:
|
| 86 | user_read_access_end();
|
| 87 | return (val == 0);
|
| 88 | err_fault:
|
| 89 | user_read_access_end();
|
| 90 | return -EFAULT;
|
| 91 | }
|
| 92 | EXPORT_SYMBOL(check_zeroed_user);
|