1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/compiler.h> 3 #include <linux/errno.h> 4 #include <linux/export.h> 5 #include <linux/fault-inject-usercopy.h> 6 #include <linux/instrumented.h> 7 #include <linux/kernel.h> 8 #include <linux/nospec.h> 9 #include <linux/string.h> 10 #include <linux/uaccess.h> 11 #include <linux/wordpart.h> 12 13 /* out-of-line parts */ 14 15 #ifndef INLINE_COPY_FROM_USER 16 unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n) 17 { 18 unsigned long res = n; 19 might_fault(); 20 if (!should_fail_usercopy() && likely(access_ok(from, n))) { 21 /* 22 * Ensure that bad access_ok() speculation will not 23 * lead to nasty side effects *after* the copy is 24 * finished: 25 */ 26 barrier_nospec(); 27 instrument_copy_from_user_before(to, from, n); 28 res = raw_copy_from_user(to, from, n); 29 instrument_copy_from_user_after(to, from, n, res); 30 } 31 if (unlikely(res)) 32 memset(to + (n - res), 0, res); 33 return res; 34 } 35 EXPORT_SYMBOL(_copy_from_user); 36 #endif 37 38 #ifndef INLINE_COPY_TO_USER 39 unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n) 40 { 41 might_fault(); 42 if (should_fail_usercopy()) 43 return n; 44 if (likely(access_ok(to, n))) { 45 instrument_copy_to_user(to, from, n); 46 n = raw_copy_to_user(to, from, n); 47 } 48 return n; 49 } 50 EXPORT_SYMBOL(_copy_to_user); 51 #endif 52 53 /** 54 * check_zeroed_user: check if a userspace buffer only contains zero bytes 55 * @from: Source address, in userspace. 56 * @size: Size of buffer. 57 * 58 * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for 59 * userspace addresses (and is more efficient because we don't care where the 60 * first non-zero byte is). 61 * 62 * Returns: 63 * * 0: There were non-zero bytes present in the buffer. 64 * * 1: The buffer was full of zero bytes. 65 * * -EFAULT: access to userspace failed. 66 */ 67 int check_zeroed_user(const void __user *from, size_t size) 68 { 69 unsigned long val; 70 uintptr_t align = (uintptr_t) from % sizeof(unsigned long); 71 72 if (unlikely(size == 0)) 73 return 1; 74 75 from -= align; 76 size += align; 77 78 if (!user_read_access_begin(from, size)) 79 return -EFAULT; 80 81 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 82 if (align) 83 val &= ~aligned_byte_mask(align); 84 85 while (size > sizeof(unsigned long)) { 86 if (unlikely(val)) 87 goto done; 88 89 from += sizeof(unsigned long); 90 size -= sizeof(unsigned long); 91 92 unsafe_get_user(val, (unsigned long __user *) from, err_fault); 93 } 94 95 if (size < sizeof(unsigned long)) 96 val &= aligned_byte_mask(size); 97 98 done: 99 user_read_access_end(); 100 return (val == 0); 101 err_fault: 102 user_read_access_end(); 103 return -EFAULT; 104 } 105 EXPORT_SYMBOL(check_zeroed_user); 106