/* * Access kernel memory without faulting. */ #include <linux/uaccess.h> #include <linux/module.h> #include <linux/mm.h> /** * probe_kernel_read(): safely attempt to read from a location * @dst: pointer to the buffer that shall take the data * @src: address to read from * @size: size of the data chunk * * Safely read from address @src to the buffer at @dst. If a kernel fault * happens, handle that and return -EFAULT. */ long probe_kernel_read(void *dst, void *src, size_t size) { long ret; mm_segment_t old_fs = get_fs(); set_fs(KERNEL_DS); pagefault_disable(); ret = __copy_from_user_inatomic(dst, (__force const void __user *)src, size); pagefault_enable(); set_fs(old_fs); return ret ? -EFAULT : 0; } EXPORT_SYMBOL_GPL(probe_kernel_read); /** * probe_kernel_write(): 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 notrace __weak probe_kernel_write(void *dst, 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); return ret ? -EFAULT : 0; } EXPORT_SYMBOL_GPL(probe_kernel_write);