1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/uaccess.h> 3 #include <linux/bitops.h> 4 5 /* out-of-line parts */ 6 7 #ifndef INLINE_COPY_FROM_USER 8 unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n) 9 { 10 unsigned long res = n; 11 might_fault(); 12 if (likely(access_ok(from, n))) { 13 kasan_check_write(to, n); 14 res = raw_copy_from_user(to, from, n); 15 } 16 if (unlikely(res)) 17 memset(to + (n - res), 0, res); 18 return res; 19 } 20 EXPORT_SYMBOL(_copy_from_user); 21 #endif 22 23 #ifndef INLINE_COPY_TO_USER 24 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) 25 { 26 might_fault(); 27 if (likely(access_ok(to, n))) { 28 kasan_check_read(from, n); 29 n = raw_copy_to_user(to, from, n); 30 } 31 return n; 32 } 33 EXPORT_SYMBOL(_copy_to_user); 34 #endif 35 36 /** 37 * check_zeroed_user: check if a userspace buffer only contains zero bytes 38 * @from: Source address, in userspace. 39 * @size: Size of buffer. 40 * 41 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for 42 * userspace addresses (and is more efficient because we don't care where the 43 * first non-zero byte is). 44 * 45 * Returns: 46 * * 0: There were non-zero bytes present in the buffer. 47 * * 1: The buffer was full of zero bytes. 48 * * -EFAULT: access to userspace failed. 49 */ 50 int check_zeroed_user(const void __user *from, size_t size) 51 { 52 unsigned long val; 53 uintptr_t align = (uintptr_t) from % sizeof(unsigned long); 54 55 if (unlikely(size == 0)) 56 return 1; 57 58 from -= align; 59 size += align; 60 61 if (!user_access_begin(from, size)) 62 return -EFAULT; 63 64 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 65 if (align) 66 val &= ~aligned_byte_mask(align); 67 68 while (size > sizeof(unsigned long)) { 69 if (unlikely(val)) 70 goto done; 71 72 from += sizeof(unsigned long); 73 size -= sizeof(unsigned long); 74 75 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 76 } 77 78 if (size < sizeof(unsigned long)) 79 val &= aligned_byte_mask(size); 80 81 done: 82 user_access_end(); 83 return (val == 0); 84 err_fault: 85 user_access_end(); 86 return -EFAULT; 87 } 88 EXPORT_SYMBOL(check_zeroed_user); 89