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