/* -*- linux-c -*- * Copy from user space functions * Copyright (C) 2005-2017 Red Hat Inc. * Copyright (C) 2005 Intel Corporation. * * This file is part of systemtap, and is free software. You can * redistribute it and/or modify it under the terms of the GNU General * Public License (GPL); either version 2, or (at your option) any * later version. */ #ifndef _STAPLINUX_COPY_C_ /* -*- linux-c -*- */ #define _STAPLINUX_COPY_C_ /** @file copy.c * @brief Functions to copy from user space. */ /** @addtogroup copy Functions to copy from user space. * Functions to copy from user space. * None of these functions will sleep (for example to allow pages * to be swapped in). It is possible (although rare) that the data * in user space will not present and these functions will return an error. * @{ */ /** Copy a NULL-terminated string from userspace. * On success, returns the length of the string (not including the trailing * NULL). * * If access to userspace fails, returns -EFAULT (some data may have been * copied). * @param dst Destination address, in kernel space. This buffer must be at * least count bytes long. * @param src Source address, in user space. * @param count Maximum number of bytes to copy, including the trailing NULL. * * If count is smaller than the length of the string, copies * count bytes and returns count. */ static long _stp_strncpy_from_user(char *dst, const char __user *src, long count) { return _stp_deref_string_nofault(dst, src, count, STP_USER_DS); } /** Copy a block of data from user space. * * If data could not be copied, this function will not modify the * destination. * * @param dst Destination address, in kernel space. * @param src Source address, in user space. * @param count Number of bytes to copy. * @return number of bytes that could not be copied. On success, * this will be zero. * */ /* XXX: see also kread/uread in loc2c-runtime.h */ static unsigned long _stp_copy_from_user(char *dst, const char __user *src, unsigned long count) { if (count) { stp_mm_segment_t oldfs; if (!stp_user_access_begin(VERIFY_READ, src, count, &oldfs, STP_USER_DS)) goto done; pagefault_disable(); if (!lookup_bad_addr(VERIFY_READ, (const unsigned long)src, count, STP_USER_DS)) count = __copy_from_user_inatomic(dst, src, count); else /* Notice that if we fail, we don't modify * the destination. In the failure case, we * can't trust 'count' to be reasonable. */ count = -EFAULT; pagefault_enable(); stp_user_access_end(oldfs); } done: return count; } /** @} */ #endif /* _STAPLINUX_COPY_C_ */