1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/bitops.h> 3 #include <linux/instrumented.h> 4 #include <linux/uaccess.h> 5 6 /* out-of-line parts */ 7 8 #ifndef INLINE_COPY_FROM_USER 9 unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n) 10 { 11 unsigned long res = n; 12 might_fault(); 13 if (likely(access_ok(from, n))) { 14 instrument_copy_from_user(to, from, n); 15 res = raw_copy_from_user(to, from, n); 16 } 17 if (unlikely(res)) 18 memset(to + (n - res), 0, res); 19 return res; 20 } 21 EXPORT_SYMBOL(_copy_from_user); 22 #endif 23 24 #ifndef INLINE_COPY_TO_USER 25 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) 26 { 27 might_fault(); 28 if (likely(access_ok(to, n))) { 29 instrument_copy_to_user(to, from, n); 30 n = raw_copy_to_user(to, from, n); 31 } 32 return n; 33 } 34 EXPORT_SYMBOL(_copy_to_user); 35 #endif 36 37 /** 38 * check_zeroed_user: check if a userspace buffer only contains zero bytes 39 * @from: Source address, in userspace. 40 * @size: Size of buffer. 41 * 42 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for 43 * userspace addresses (and is more efficient because we don't care where the 44 * first non-zero byte is). 45 * 46 * Returns: 47 * * 0: There were non-zero bytes present in the buffer. 48 * * 1: The buffer was full of zero bytes. 49 * * -EFAULT: access to userspace failed. 50 */ 51 int check_zeroed_user(const void __user *from, size_t size) 52 { 53 unsigned long val; 54 uintptr_t align = (uintptr_t) from % sizeof(unsigned long); 55 56 if (unlikely(size == 0)) 57 return 1; 58 59 from -= align; 60 size += align; 61 62 if (!user_read_access_begin(from, size)) 63 return -EFAULT; 64 65 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 66 if (align) 67 val &= ~aligned_byte_mask(align); 68 69 while (size > sizeof(unsigned long)) { 70 if (unlikely(val)) 71 goto done; 72 73 from += sizeof(unsigned long); 74 size -= sizeof(unsigned long); 75 76 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 77 } 78 79 if (size < sizeof(unsigned long)) 80 val &= aligned_byte_mask(size); 81 82 done: 83 user_read_access_end(); 84 return (val == 0); 85 err_fault: 86 user_read_access_end(); 87 return -EFAULT; 88 } 89 EXPORT_SYMBOL(check_zeroed_user); 90