/* * 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> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at your option) * any later version. * */ #include <crypto/scatterwalk.h> #include <linux/kernel.h> #include <linux/mm.h> #include <linux/module.h> #include <linux/pagemap.h> #include <linux/highmem.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_start(struct scatter_walk *walk, struct scatterlist *sg) { walk->sg = sg; BUG_ON(!sg->length); walk->offset = sg->offset; } EXPORT_SYMBOL_GPL(scatterwalk_start); void *scatterwalk_map(struct scatter_walk *walk) { return kmap_atomic(scatterwalk_page(walk)) + offset_in_page(walk->offset); } EXPORT_SYMBOL_GPL(scatterwalk_map); static void scatterwalk_pagedone(struct scatter_walk *walk, int out, unsigned int more) { if (out) { struct page *page; page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as * PageSlab cannot be optimised away per se due to * use of volatile pointer. */ if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page)) flush_dcache_page(page); } if (more) { walk->offset += PAGE_SIZE - 1; walk->offset &= PAGE_MASK; if (walk->offset >= walk->sg->offset + walk->sg->length) scatterwalk_start(walk, sg_next(walk->sg)); } } void scatterwalk_done(struct scatter_walk *walk, int out, int more) { if (!(scatterwalk_pagelen(walk) & (PAGE_SIZE - 1)) || !more) scatterwalk_pagedone(walk, out, more); } EXPORT_SYMBOL_GPL(scatterwalk_done); 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; 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); } } 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); if (sg_page(sg) == virt_to_page(buf) && sg->offset == offset_in_page(buf)) return; scatterwalk_start(&walk, sg); scatterwalk_copychunks(buf, &walk, nbytes, out); scatterwalk_done(&walk, out, 0); } EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes) { int offset = 0, n = 0; /* num_bytes is too small */ if (num_bytes < sg->length) return -1; do { offset += sg->length; n++; sg = sg_next(sg); /* num_bytes is too large */ if (unlikely(!sg && (num_bytes < offset))) return -1; } while (sg && (num_bytes > offset)); return n; } EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen); 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), 0, 2); return dst; } EXPORT_SYMBOL_GPL(scatterwalk_ffwd);