// 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> bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,		size_t size){	return true;} #ifdef HAVE_GET_KERNEL_NOFAULT #define copy_from_kernel_nofault_loop(dst, src, len, type, err_label)	\	while (len >= sizeof(type)) {					\		__get_kernel_nofault(dst, src, type, err_label);		\		dst += sizeof(type);					\		src += sizeof(type);					\		len -= sizeof(type);					\	} long copy_from_kernel_nofault(void *dst, const void *src, size_t size){	if (!copy_from_kernel_nofault_allowed(src, size))		return -ERANGE; 	pagefault_disable();	copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);	copy_from_kernel_nofault_loop(dst, src, size, u32, Efault);	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);		\		dst += sizeof(type);					\		src += sizeof(type);					\		len -= sizeof(type);					\	} long copy_to_kernel_nofault(void *dst, const void *src, size_t size){	pagefault_disable();	copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);	copy_to_kernel_nofault_loop(dst, src, size, u32, Efault);	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[-1] = '\0';	return -EFAULT;}#else /* HAVE_GET_KERNEL_NOFAULT *//** * copy_from_kernel_nofault(): safely attempt to read from kernel-space * @dst: pointer to the buffer that shall take the data * @src: address to read from * @size: size of the data chunk * * Safely read from kernel address @src to the buffer at @dst.  If a kernel * fault happens, handle that and return -EFAULT.  If @src is not a valid kernel * address, return -ERANGE. * * We ensure that the copy_from_user is executed in atomic context so that * do_page_fault() doesn't attempt to take mmap_lock.  This makes * copy_from_kernel_nofault() suitable for use within regions where the caller * already holds mmap_lock, or other locks which nest inside mmap_lock. */long copy_from_kernel_nofault(void *dst, const void *src, size_t size){	long ret;	mm_segment_t old_fs = get_fs(); 	if (!copy_from_kernel_nofault_allowed(src, size))		return -ERANGE; 	set_fs(KERNEL_DS);	pagefault_disable();	ret = __copy_from_user_inatomic(dst, (__force const void __user *)src,			size);	pagefault_enable();	set_fs(old_fs); 	if (ret)		return -EFAULT;	return 0;}EXPORT_SYMBOL_GPL(copy_from_kernel_nofault); /** * copy_to_kernel_nofault(): safely attempt to write to a 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_kernel_nofault(void *dst, const void *src, size_t size){	long ret;	mm_segment_t old_fs = get_fs(); 	set_fs(KERNEL_DS);	pagefault_disable();	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);	pagefault_enable();	set_fs(old_fs); 	if (ret)		return -EFAULT;	return 0;} /** * strncpy_from_kernel_nofault: - Copy a NUL terminated string from unsafe *				 address. * @dst:   Destination address, in kernel space.  This buffer must be at *         least @count bytes long. * @unsafe_addr: Unsafe address. * @count: Maximum number of bytes to copy, including the trailing NUL. * * Copies a NUL-terminated string from unsafe 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 @unsafe_addr is not a valid kernel address, return * -ERANGE. * * 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_kernel_nofault(char *dst, const void *unsafe_addr, long count){	mm_segment_t old_fs = get_fs();	const void *src = unsafe_addr;	long ret; 	if (unlikely(count <= 0))		return 0;	if (!copy_from_kernel_nofault_allowed(unsafe_addr, count))		return -ERANGE; 	set_fs(KERNEL_DS);	pagefault_disable(); 	do {		ret = __get_user(*dst++, (const char __user __force *)src++);	} while (dst[-1] && ret == 0 && src - unsafe_addr < count); 	dst[-1] = '\0';	pagefault_enable();	set_fs(old_fs); 	return ret ? -EFAULT : src - unsafe_addr;}#endif /* HAVE_GET_KERNEL_NOFAULT */ /** * 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;	mm_segment_t old_fs = force_uaccess_begin(); 	if (access_ok(src, size)) {		pagefault_disable();		ret = __copy_from_user_inatomic(dst, src, size);		pagefault_enable();	}	force_uaccess_end(old_fs); 	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;	mm_segment_t old_fs = force_uaccess_begin(); 	if (access_ok(dst, size)) {		pagefault_disable();		ret = __copy_to_user_inatomic(dst, src, size);		pagefault_enable();	}	force_uaccess_end(old_fs); 	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){	mm_segment_t old_fs;	long ret; 	if (unlikely(count <= 0))		return 0; 	old_fs = force_uaccess_begin();	pagefault_disable();	ret = strncpy_from_user(dst, unsafe_addr, count);	pagefault_enable();	force_uaccess_end(old_fs); 	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){	mm_segment_t old_fs;	int ret; 	old_fs = force_uaccess_begin();	pagefault_disable();	ret = strnlen_user(unsafe_addr, count);	pagefault_enable();	force_uaccess_end(old_fs); 	return ret;}