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