// SPDX-License-Identifier: GPL-2.0-only/* * Access kernel or user memory without faulting. */#include <linux/export.h>#include <linux/mm.h>#include <linux/uaccess.h>#include <asm/tlb.h> bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,		size_t size){	return true;} /* * The below only uses kmsan_check_memory() to ensure uninitialized kernel * memory isn't leaked. */#define copy_from_kernel_nofault_loop(dst, src, len, type, err_label)	\	while (len >= sizeof(type)) {					\		__get_kernel_nofault(dst, src, type, err_label);	\		kmsan_check_memory(src, sizeof(type));			\		dst += sizeof(type);					\		src += sizeof(type);					\		len -= sizeof(type);					\	} long copy_from_kernel_nofault(void *dst, const void *src, size_t size){	unsigned long align = 0; 	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))		align = (unsigned long)dst | (unsigned long)src; 	if (!copy_from_kernel_nofault_allowed(src, size))		return -ERANGE; 	pagefault_disable();	if (!(align & 7))		copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);	if (!(align & 3))		copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);	if (!(align & 1))		copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);	copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);	pagefault_enable();	return 0;Efault:	pagefault_enable();	return -EFAULT;}EXPORT_SYMBOL_GPL(copy_from_kernel_nofault); #define copy_to_kernel_nofault_loop(dst, src, len, type, err_label)	\	while (len >= sizeof(type)) {					\		__put_kernel_nofault(dst, src, type, err_label);	\		instrument_write(dst, sizeof(type));			\		dst += sizeof(type);					\		src += sizeof(type);					\		len -= sizeof(type);					\	} long copy_to_kernel_nofault(void *dst, const void *src, size_t size){	unsigned long align = 0; 	if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))		align = (unsigned long)dst | (unsigned long)src; 	pagefault_disable();	if (!(align & 7))		copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);	if (!(align & 3))		copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);	if (!(align & 1))		copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);	copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);	pagefault_enable();	return 0;Efault:	pagefault_enable();	return -EFAULT;} long strncpy_from_kernel_nofault(char *dst, const void *unsafe_addr, long count){	const void *src = unsafe_addr; 	if (unlikely(count <= 0))		return 0;	if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))		return -ERANGE; 	pagefault_disable();	do {		__get_kernel_nofault(dst, src, u8, Efault);		dst++;		src++;	} while (dst[-1] && src - unsafe_addr < count);	pagefault_enable(); 	dst[-1] = '\0';	return src - unsafe_addr;Efault:	pagefault_enable();	dst[0] = '\0';	return -EFAULT;} /** * copy_from_user_nofault(): safely attempt to read from a user-space location * @dst: pointer to the buffer that shall take the data * @src: address to read from. This must be a user address. * @size: size of the data chunk * * Safely read from user address @src to the buffer at @dst. If a kernel fault * happens, handle that and return -EFAULT. */long copy_from_user_nofault(void *dst, const void __user *src, size_t size){	long ret = -EFAULT; 	if (!__access_ok(src, size))		return ret; 	if (!nmi_uaccess_okay())		return ret; 	pagefault_disable();	ret = __copy_from_user_inatomic(dst, src, size);	pagefault_enable(); 	if (ret)		return -EFAULT;	return 0;}EXPORT_SYMBOL_GPL(copy_from_user_nofault); /** * copy_to_user_nofault(): safely attempt to write to a user-space location * @dst: address to write to * @src: pointer to the data that shall be written * @size: size of the data chunk * * Safely write to address @dst from the buffer at @src.  If a kernel fault * happens, handle that and return -EFAULT. */long copy_to_user_nofault(void __user *dst, const void *src, size_t size){	long ret = -EFAULT; 	if (access_ok(dst, size)) {		pagefault_disable();		ret = __copy_to_user_inatomic(dst, src, size);		pagefault_enable();	} 	if (ret)		return -EFAULT;	return 0;}EXPORT_SYMBOL_GPL(copy_to_user_nofault); /** * strncpy_from_user_nofault: - Copy a NUL terminated string from unsafe user *				address. * @dst:   Destination address, in kernel space.  This buffer must be at *         least @count bytes long. * @unsafe_addr: Unsafe user address. * @count: Maximum number of bytes to copy, including the trailing NUL. * * Copies a NUL-terminated string from unsafe user address to kernel buffer. * * On success, returns the length of the string INCLUDING the trailing NUL. * * If access fails, returns -EFAULT (some data may have been copied * and the trailing NUL added). * * If @count is smaller than the length of the string, copies @count-1 bytes, * sets the last byte of @dst buffer to NUL and returns @count. */long strncpy_from_user_nofault(char *dst, const void __user *unsafe_addr,			      long count){	long ret; 	if (unlikely(count <= 0))		return 0; 	pagefault_disable();	ret = strncpy_from_user(dst, unsafe_addr, count);	pagefault_enable(); 	if (ret >= count) {		ret = count;		dst[ret - 1] = '\0';	} else if (ret >= 0) {		ret++;	} 	return ret;} /** * strnlen_user_nofault: - Get the size of a user string INCLUDING final NUL. * @unsafe_addr: The string to measure. * @count: Maximum count (including NUL) * * Get the size of a NUL-terminated string in user space without pagefault. * * Returns the size of the string INCLUDING the terminating NUL. * * If the string is too long, returns a number larger than @count. User * has to check the return value against "> count". * On exception (or invalid count), returns 0. * * Unlike strnlen_user, this can be used from IRQ handler etc. because * it disables pagefaults. */long strnlen_user_nofault(const void __user *unsafe_addr, long count){	int ret; 	pagefault_disable();	ret = strnlen_user(unsafe_addr, count);	pagefault_enable(); 	return ret;} void __copy_overflow(int size, unsigned long count){	WARN(1, "Buffer overflow detected (%d < %lu)!\n", size, count);}EXPORT_SYMBOL(__copy_overflow);