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(dst: to, src: from, size: n); |
24 | instrument_copy_from_user_after(to, from, n, left: 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(dst: to, src: from, size: 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); |
101 | |