// SPDX-License-Identifier: GPL-2.0-or-later /* * Cryptographic API. * * Cipher operations. * * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> * 2002 Adam J. Richter <adam@yggdrasil.com> * 2004 Jean-Luc Cooke <jlcooke@certainkey.com> */ #include <crypto/scatterwalk.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/scatterlist.h> static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) { void *src = out ? buf : sgdata; void *dst = out ? sgdata : buf; memcpy(dst, src, nbytes); } void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, size_t nbytes, int out) { for (;;) { unsigned int len_this_page = scatterwalk_pagelen(walk); u8 *vaddr; if (len_this_page > nbytes) len_this_page = nbytes; if (out != 2) { vaddr = scatterwalk_map(walk); memcpy_dir(buf, vaddr, len_this_page, out); scatterwalk_unmap(vaddr); } scatterwalk_advance(walk, len_this_page); if (nbytes == len_this_page) break; buf += len_this_page; nbytes -= len_this_page; scatterwalk_pagedone(walk, out & 1, 1); } } EXPORT_SYMBOL_GPL(scatterwalk_copychunks); void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, unsigned int start, unsigned int nbytes, int out) { struct scatter_walk walk; struct scatterlist tmp[2]; if (!nbytes) return; sg = scatterwalk_ffwd(tmp, sg, start); scatterwalk_start(&walk, sg); scatterwalk_copychunks(buf, &walk, nbytes, out); scatterwalk_done(&walk, out, 0); } EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], struct scatterlist *src, unsigned int len) { for (;;) { if (!len) return src; if (src->length > len) break; len -= src->length; src = sg_next(src); } sg_init_table(dst, 2); sg_set_page(dst, sg_page(src), src->length - len, src->offset + len); scatterwalk_crypto_chain(dst, sg_next(src), 2); return dst; } EXPORT_SYMBOL_GPL(scatterwalk_ffwd);