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_before(to, from, n); 16 res = raw_copy_from_user(to, from, n); 17 instrument_copy_from_user_after(to, from, n, res); 18 } 19 if (unlikely(res)) 20 memset(to + (n - res), 0, res); 21 return res; 22 } 23 EXPORT_SYMBOL(_copy_from_user); 24 #endif 25 26 #ifndef INLINE_COPY_TO_USER 27 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) 28 { 29 might_fault(); 30 if (should_fail_usercopy()) 31 return n; 32 if (likely(access_ok(to, n))) { 33 instrument_copy_to_user(to, from, n); 34 n = raw_copy_to_user(to, from, n); 35 } 36 return n; 37 } 38 EXPORT_SYMBOL(_copy_to_user); 39 #endif 40 41 /** 42 * check_zeroed_user: check if a userspace buffer only contains zero bytes 43 * @from: Source address, in userspace. 44 * @size: Size of buffer. 45 * 46 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for 47 * userspace addresses (and is more efficient because we don't care where the 48 * first non-zero byte is). 49 * 50 * Returns: 51 * * 0: There were non-zero bytes present in the buffer. 52 * * 1: The buffer was full of zero bytes. 53 * * -EFAULT: access to userspace failed. 54 */ 55 int check_zeroed_user(const void __user *from, size_t size) 56 { 57 unsigned long val; 58 uintptr_t align = (uintptr_t) from % sizeof(unsigned long); 59 60 if (unlikely(size == 0)) 61 return 1; 62 63 from -= align; 64 size += align; 65 66 if (!user_read_access_begin(from, size)) 67 return -EFAULT; 68 69 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 70 if (align) 71 val &= ~aligned_byte_mask(align); 72 73 while (size > sizeof(unsigned long)) { 74 if (unlikely(val)) 75 goto done; 76 77 from += sizeof(unsigned long); 78 size -= sizeof(unsigned long); 79 80 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 81 } 82 83 if (size < sizeof(unsigned long)) 84 val &= aligned_byte_mask(size); 85 86 done: 87 user_read_access_end(); 88 return (val == 0); 89 err_fault: 90 user_read_access_end(); 91 return -EFAULT; 92 } 93 EXPORT_SYMBOL(check_zeroed_user); 94