1 /* 2 * Cryptographic API. 3 * 4 * Cipher operations. 5 * 6 * Copyright (c) 2002 James Morris <jmorris@intercode.com.au> 7 * 2002 Adam J. Richter <adam@yggdrasil.com> 8 * 2004 Jean-Luc Cooke <jlcooke@certainkey.com> 9 * 10 * This program is free software; you can redistribute it and/or modify it 11 * under the terms of the GNU General Public License as published by the Free 12 * Software Foundation; either version 2 of the License, or (at your option) 13 * any later version. 14 * 15 */ 16 17 #include <crypto/scatterwalk.h> 18 #include <linux/kernel.h> 19 #include <linux/mm.h> 20 #include <linux/module.h> 21 #include <linux/pagemap.h> 22 #include <linux/highmem.h> 23 #include <linux/scatterlist.h> 24 25 static inline void memcpy_dir(void *buf, void *sgdata, size_t nbytes, int out) 26 { 27 void *src = out ? buf : sgdata; 28 void *dst = out ? sgdata : buf; 29 30 memcpy(dst, src, nbytes); 31 } 32 33 void scatterwalk_start(struct scatter_walk *walk, struct scatterlist *sg) 34 { 35 walk->sg = sg; 36 37 BUG_ON(!sg->length); 38 39 walk->offset = sg->offset; 40 } 41 EXPORT_SYMBOL_GPL(scatterwalk_start); 42 43 void *scatterwalk_map(struct scatter_walk *walk) 44 { 45 return kmap_atomic(scatterwalk_page(walk)) + 46 offset_in_page(walk->offset); 47 } 48 EXPORT_SYMBOL_GPL(scatterwalk_map); 49 50 static void scatterwalk_pagedone(struct scatter_walk *walk, int out, 51 unsigned int more) 52 { 53 if (out) { 54 struct page *page; 55 56 page = sg_page(walk->sg) + ((walk->offset - 1) >> PAGE_SHIFT); 57 /* Test ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE first as 58 * PageSlab cannot be optimised away per se due to 59 * use of volatile pointer. 60 */ 61 if (ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE && !PageSlab(page)) 62 flush_dcache_page(page); 63 } 64 65 if (more) { 66 walk->offset += PAGE_SIZE - 1; 67 walk->offset &= PAGE_MASK; 68 if (walk->offset >= walk->sg->offset + walk->sg->length) 69 scatterwalk_start(walk, sg_next(walk->sg)); 70 } 71 } 72 73 void scatterwalk_done(struct scatter_walk *walk, int out, int more) 74 { 75 if (!(scatterwalk_pagelen(walk) & (PAGE_SIZE - 1)) || !more) 76 scatterwalk_pagedone(walk, out, more); 77 } 78 EXPORT_SYMBOL_GPL(scatterwalk_done); 79 80 void scatterwalk_copychunks(void *buf, struct scatter_walk *walk, 81 size_t nbytes, int out) 82 { 83 for (;;) { 84 unsigned int len_this_page = scatterwalk_pagelen(walk); 85 u8 *vaddr; 86 87 if (len_this_page > nbytes) 88 len_this_page = nbytes; 89 90 vaddr = scatterwalk_map(walk); 91 memcpy_dir(buf, vaddr, len_this_page, out); 92 scatterwalk_unmap(vaddr); 93 94 scatterwalk_advance(walk, len_this_page); 95 96 if (nbytes == len_this_page) 97 break; 98 99 buf += len_this_page; 100 nbytes -= len_this_page; 101 102 scatterwalk_pagedone(walk, out, 1); 103 } 104 } 105 EXPORT_SYMBOL_GPL(scatterwalk_copychunks); 106 107 void scatterwalk_map_and_copy(void *buf, struct scatterlist *sg, 108 unsigned int start, unsigned int nbytes, int out) 109 { 110 struct scatter_walk walk; 111 struct scatterlist tmp[2]; 112 113 if (!nbytes) 114 return; 115 116 sg = scatterwalk_ffwd(tmp, sg, start); 117 118 if (sg_page(sg) == virt_to_page(buf) && 119 sg->offset == offset_in_page(buf)) 120 return; 121 122 scatterwalk_start(&walk, sg); 123 scatterwalk_copychunks(buf, &walk, nbytes, out); 124 scatterwalk_done(&walk, out, 0); 125 } 126 EXPORT_SYMBOL_GPL(scatterwalk_map_and_copy); 127 128 int scatterwalk_bytes_sglen(struct scatterlist *sg, int num_bytes) 129 { 130 int offset = 0, n = 0; 131 132 /* num_bytes is too small */ 133 if (num_bytes < sg->length) 134 return -1; 135 136 do { 137 offset += sg->length; 138 n++; 139 sg = sg_next(sg); 140 141 /* num_bytes is too large */ 142 if (unlikely(!sg && (num_bytes < offset))) 143 return -1; 144 } while (sg && (num_bytes > offset)); 145 146 return n; 147 } 148 EXPORT_SYMBOL_GPL(scatterwalk_bytes_sglen); 149 150 struct scatterlist *scatterwalk_ffwd(struct scatterlist dst[2], 151 struct scatterlist *src, 152 unsigned int len) 153 { 154 for (;;) { 155 if (!len) 156 return src; 157 158 if (src->length > len) 159 break; 160 161 len -= src->length; 162 src = sg_next(src); 163 } 164 165 sg_init_table(dst, 2); 166 sg_set_page(dst, sg_page(src), src->length - len, src->offset + len); 167 scatterwalk_crypto_chain(dst, sg_next(src), 0, 2); 168 169 return dst; 170 } 171 EXPORT_SYMBOL_GPL(scatterwalk_ffwd); 172