| 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
| 2 | /* |
| 3 | * Cryptographic API. |
| 4 | * |
| 5 | * Cipher operations. |
| 6 | * |
| 7 | * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> |
| 8 | * 2002 Adam J. Richter <adam@yggdrasil.com> |
| 9 | * 2004 Jean-Luc Cooke <jlcooke@certainkey.com> |
| 10 | */ |
| 11 | |
| 12 | #include <crypto/scatterwalk.h> |
| 13 | #include <linux/kernel.h> |
| 14 | #include <linux/mm.h> |
| 15 | #include <linux/module.h> |
| 16 | #include <linux/scatterlist.h> |
| 17 | |
| 18 | static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) |
| 19 | { |
| 20 | void *src = out ? buf : sgdata; |
| 21 | void *dst = out ? sgdata : buf; |
| 22 | |
| 23 | memcpy(dst, src, nbytes); |
| 24 | } |
| 25 | |
| 26 | void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, |
| 27 | size_t nbytes, int out) |
| 28 | { |
| 29 | for (;;) { |
| 30 | unsigned int len_this_page = scatterwalk_pagelen(walk); |
| 31 | u8 *vaddr; |
| 32 | |
| 33 | if (len_this_page > nbytes) |
| 34 | len_this_page = nbytes; |
| 35 | |
| 36 | if (out != 2) { |
| 37 | vaddr = scatterwalk_map(walk); |
| 38 | memcpy_dir(buf, vaddr, len_this_page, out); |
| 39 | scatterwalk_unmap(vaddr); |
| 40 | } |
| 41 | |
| 42 | scatterwalk_advance(walk, len_this_page); |
| 43 | |
| 44 | if (nbytes == len_this_page) |
| 45 | break; |
| 46 | |
| 47 | buf += len_this_page; |
| 48 | nbytes -= len_this_page; |
| 49 | |
| 50 | scatterwalk_pagedone(walk, out & 1, 1); |
| 51 | } |
| 52 | } |
| 53 | EXPORT_SYMBOL_GPL(scatterwalk_copychunks); |
| 54 | |
| 55 | void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, |
| 56 | unsigned int start, unsigned int nbytes, int out) |
| 57 | { |
| 58 | struct scatter_walk walk; |
| 59 | struct scatterlist tmp[2]; |
| 60 | |
| 61 | if (!nbytes) |
| 62 | return; |
| 63 | |
| 64 | sg = scatterwalk_ffwd(tmp, sg, start); |
| 65 | |
| 66 | scatterwalk_start(&walk, sg); |
| 67 | scatterwalk_copychunks(buf, &walk, nbytes, out); |
| 68 | scatterwalk_done(&walk, out, 0); |
| 69 | } |
| 70 | EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); |
| 71 | |
| 72 | struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], |
| 73 | struct scatterlist *src, |
| 74 | unsigned int len) |
| 75 | { |
| 76 | for (;;) { |
| 77 | if (!len) |
| 78 | return src; |
| 79 | |
| 80 | if (src->length > len) |
| 81 | break; |
| 82 | |
| 83 | len -= src->length; |
| 84 | src = sg_next(src); |
| 85 | } |
| 86 | |
| 87 | sg_init_table(dst, 2); |
| 88 | sg_set_page(dst, sg_page(src), src->length - len, src->offset + len); |
| 89 | scatterwalk_crypto_chain(dst, sg_next(src), 2); |
| 90 | |
| 91 | return dst; |
| 92 | } |
| 93 | EXPORT_SYMBOL_GPL(scatterwalk_ffwd); |