| 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 | #include <linux/nospec.h> |
| 7 | |
| 8 | /* out-of-line parts */ |
| 9 | |
| 10 | #ifndef INLINE_COPY_FROM_USER |
| 11 | unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n) |
| 12 | { |
| 13 | unsigned long res = n; |
| 14 | might_fault(); |
| 15 | if (!should_fail_usercopy() && likely(access_ok(from, n))) { |
| 16 | /* |
| 17 | * Ensure that bad access_ok() speculation will not |
| 18 | * lead to nasty side effects *after* the copy is |
| 19 | * finished: |
| 20 | */ |
| 21 | barrier_nospec(); |
| 22 | instrument_copy_from_user_before(to, from, n); |
| 23 | res = raw_copy_from_user(to, from, n); |
| 24 | instrument_copy_from_user_after(to, from, n, res); |
| 25 | } |
| 26 | if (unlikely(res)) |
| 27 | memset(to + (n - res), 0, res); |
| 28 | return res; |
| 29 | } |
| 30 | EXPORT_SYMBOL(_copy_from_user); |
| 31 | #endif |
| 32 | |
| 33 | #ifndef INLINE_COPY_TO_USER |
| 34 | unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) |
| 35 | { |
| 36 | might_fault(); |
| 37 | if (should_fail_usercopy()) |
| 38 | return n; |
| 39 | if (likely(access_ok(to, n))) { |
| 40 | instrument_copy_to_user(to, from, n); |
| 41 | n = raw_copy_to_user(to, from, n); |
| 42 | } |
| 43 | return n; |
| 44 | } |
| 45 | EXPORT_SYMBOL(_copy_to_user); |
| 46 | #endif |
| 47 | |
| 48 | /** |
| 49 | * check_zeroed_user: check if a userspace buffer only contains zero bytes |
| 50 | * @from: Source address, in userspace. |
| 51 | * @size: Size of buffer. |
| 52 | * |
| 53 | * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for |
| 54 | * userspace addresses (and is more efficient because we don't care where the |
| 55 | * first non-zero byte is). |
| 56 | * |
| 57 | * Returns: |
| 58 | * * 0: There were non-zero bytes present in the buffer. |
| 59 | * * 1: The buffer was full of zero bytes. |
| 60 | * * -EFAULT: access to userspace failed. |
| 61 | */ |
| 62 | int check_zeroed_user(const void __user *from, size_t size) |
| 63 | { |
| 64 | unsigned long val; |
| 65 | uintptr_t align = (uintptr_t) from % sizeof(unsigned long); |
| 66 | |
| 67 | if (unlikely(size == 0)) |
| 68 | return 1; |
| 69 | |
| 70 | from -= align; |
| 71 | size += align; |
| 72 | |
| 73 | if (!user_read_access_begin(from, size)) |
| 74 | return -EFAULT; |
| 75 | |
| 76 | unsafe_get_user(val, (unsigned long __user *) from, err_fault); |
| 77 | if (align) |
| 78 | val &= ~aligned_byte_mask(align); |
| 79 | |
| 80 | while (size > sizeof(unsigned long)) { |
| 81 | if (unlikely(val)) |
| 82 | goto done; |
| 83 | |
| 84 | from += sizeof(unsigned long); |
| 85 | size -= sizeof(unsigned long); |
| 86 | |
| 87 | unsafe_get_user(val, (unsigned long __user *) from, err_fault); |
| 88 | } |
| 89 | |
| 90 | if (size < sizeof(unsigned long)) |
| 91 | val &= aligned_byte_mask(size); |
| 92 | |
| 93 | done: |
| 94 | user_read_access_end(); |
| 95 | return (val == 0); |
| 96 | err_fault: |
| 97 | user_read_access_end(); |
| 98 | return -EFAULT; |
| 99 | } |
| 100 | EXPORT_SYMBOL(check_zeroed_user); |