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