116 lines
2.8 KiB
C
116 lines
2.8 KiB
C
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/*
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* Cryptographic API.
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*
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* Cipher operations.
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*
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* Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
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* 2002 Adam J. Richter <adam@yggdrasil.com>
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* 2004 Jean-Luc Cooke <jlcooke@certainkey.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/highmem.h>
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#include <asm/bug.h>
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#include <asm/scatterlist.h>
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#include "internal.h"
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#include "scatterwalk.h"
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enum km_type crypto_km_types[] = {
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KM_USER0,
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KM_USER1,
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KM_SOFTIRQ0,
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KM_SOFTIRQ1,
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};
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static void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out)
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{
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if (out)
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memcpy(sgdata, buf, nbytes);
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else
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memcpy(buf, sgdata, nbytes);
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}
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void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg)
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{
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unsigned int rest_of_page;
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walk->sg = sg;
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walk->page = sg->page;
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walk->len_this_segment = sg->length;
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BUG_ON(!sg->length);
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rest_of_page = PAGE_CACHE_SIZE - (sg->offset & (PAGE_CACHE_SIZE - 1));
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walk->len_this_page = min(sg->length, rest_of_page);
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walk->offset = sg->offset;
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}
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void scatterwalk_map(struct scatter_walk *walk, int out)
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{
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walk->data = crypto_kmap(walk->page, out) + walk->offset;
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}
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static inline void scatterwalk_unmap(struct scatter_walk *walk, int out)
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{
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/* walk->data may be pointing the first byte of the next page;
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however, we know we transfered at least one byte. So,
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walk->data - 1 will be a virtual address in the mapped page. */
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crypto_kunmap(walk->data - 1, out);
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}
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static void scatterwalk_pagedone(struct scatter_walk *walk, int out,
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unsigned int more)
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{
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if (out)
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flush_dcache_page(walk->page);
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if (more) {
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walk->len_this_segment -= walk->len_this_page;
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if (walk->len_this_segment) {
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walk->page++;
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walk->len_this_page = min(walk->len_this_segment,
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(unsigned)PAGE_CACHE_SIZE);
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walk->offset = 0;
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}
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else
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scatterwalk_start(walk, sg_next(walk->sg));
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}
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}
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void scatterwalk_done(struct scatter_walk *walk, int out, int more)
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{
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scatterwalk_unmap(walk, out);
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if (walk->len_this_page == 0 || !more)
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scatterwalk_pagedone(walk, out, more);
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}
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/*
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* Do not call this unless the total length of all of the fragments
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* has been verified as multiple of the block size.
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*/
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int scatterwalk_copychunks(void *buf, struct scatter_walk *walk,
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size_t nbytes, int out)
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{
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do {
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memcpy_dir(buf, walk->data, walk->len_this_page, out);
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buf += walk->len_this_page;
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nbytes -= walk->len_this_page;
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scatterwalk_unmap(walk, out);
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scatterwalk_pagedone(walk, out, 1);
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scatterwalk_map(walk, out);
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} while (nbytes > walk->len_this_page);
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memcpy_dir(buf, walk->data, nbytes, out);
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return nbytes;
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}
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