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