Herbert Xu | 806d183 | 2007-12-05 12:10:53 +1100 | [diff] [blame] | 1 | /* |
| 2 | * eseqiv: Encrypted Sequence Number IV Generator |
| 3 | * |
| 4 | * This generator generates an IV based on a sequence number by xoring it |
| 5 | * with a salt and then encrypting it with the same key as used to encrypt |
| 6 | * the plain text. This algorithm requires that the block size be equal |
| 7 | * to the IV size. It is mainly useful for CBC. |
| 8 | * |
| 9 | * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> |
| 10 | * |
| 11 | * This program is free software; you can redistribute it and/or modify it |
| 12 | * under the terms of the GNU General Public License as published by the Free |
| 13 | * Software Foundation; either version 2 of the License, or (at your option) |
| 14 | * any later version. |
| 15 | * |
| 16 | */ |
| 17 | |
| 18 | #include <crypto/internal/skcipher.h> |
| 19 | #include <crypto/scatterwalk.h> |
| 20 | #include <linux/err.h> |
| 21 | #include <linux/init.h> |
| 22 | #include <linux/kernel.h> |
| 23 | #include <linux/mm.h> |
| 24 | #include <linux/module.h> |
| 25 | #include <linux/random.h> |
| 26 | #include <linux/scatterlist.h> |
| 27 | #include <linux/spinlock.h> |
| 28 | #include <linux/string.h> |
| 29 | |
| 30 | struct eseqiv_request_ctx { |
| 31 | struct scatterlist src[2]; |
| 32 | struct scatterlist dst[2]; |
| 33 | char tail[]; |
| 34 | }; |
| 35 | |
| 36 | struct eseqiv_ctx { |
| 37 | spinlock_t lock; |
| 38 | unsigned int reqoff; |
| 39 | char salt[]; |
| 40 | }; |
| 41 | |
| 42 | static void eseqiv_complete2(struct skcipher_givcrypt_request *req) |
| 43 | { |
| 44 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); |
| 45 | struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req); |
| 46 | |
| 47 | memcpy(req->giv, PTR_ALIGN((u8 *)reqctx->tail, |
| 48 | crypto_ablkcipher_alignmask(geniv) + 1), |
| 49 | crypto_ablkcipher_ivsize(geniv)); |
| 50 | } |
| 51 | |
| 52 | static void eseqiv_complete(struct crypto_async_request *base, int err) |
| 53 | { |
| 54 | struct skcipher_givcrypt_request *req = base->data; |
| 55 | |
| 56 | if (err) |
| 57 | goto out; |
| 58 | |
| 59 | eseqiv_complete2(req); |
| 60 | |
| 61 | out: |
| 62 | skcipher_givcrypt_complete(req, err); |
| 63 | } |
| 64 | |
| 65 | static void eseqiv_chain(struct scatterlist *head, struct scatterlist *sg, |
| 66 | int chain) |
| 67 | { |
| 68 | if (chain) { |
| 69 | head->length += sg->length; |
| 70 | sg = scatterwalk_sg_next(sg); |
| 71 | } |
| 72 | |
| 73 | if (sg) |
| 74 | scatterwalk_sg_chain(head, 2, sg); |
| 75 | else |
| 76 | sg_mark_end(head); |
| 77 | } |
| 78 | |
| 79 | static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req) |
| 80 | { |
| 81 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); |
| 82 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); |
| 83 | struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req); |
| 84 | struct ablkcipher_request *subreq; |
| 85 | crypto_completion_t complete; |
| 86 | void *data; |
| 87 | struct scatterlist *osrc, *odst; |
| 88 | struct scatterlist *dst; |
| 89 | struct page *srcp; |
| 90 | struct page *dstp; |
| 91 | u8 *giv; |
| 92 | u8 *vsrc; |
| 93 | u8 *vdst; |
| 94 | __be64 seq; |
| 95 | unsigned int ivsize; |
| 96 | unsigned int len; |
| 97 | int err; |
| 98 | |
| 99 | subreq = (void *)(reqctx->tail + ctx->reqoff); |
| 100 | ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); |
| 101 | |
| 102 | giv = req->giv; |
| 103 | complete = req->creq.base.complete; |
| 104 | data = req->creq.base.data; |
| 105 | |
| 106 | osrc = req->creq.src; |
| 107 | odst = req->creq.dst; |
| 108 | srcp = sg_page(osrc); |
| 109 | dstp = sg_page(odst); |
| 110 | vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset; |
| 111 | vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset; |
| 112 | |
| 113 | ivsize = crypto_ablkcipher_ivsize(geniv); |
| 114 | |
| 115 | if (vsrc != giv + ivsize && vdst != giv + ivsize) { |
| 116 | giv = PTR_ALIGN((u8 *)reqctx->tail, |
| 117 | crypto_ablkcipher_alignmask(geniv) + 1); |
| 118 | complete = eseqiv_complete; |
| 119 | data = req; |
| 120 | } |
| 121 | |
| 122 | ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete, |
| 123 | data); |
| 124 | |
| 125 | sg_init_table(reqctx->src, 2); |
| 126 | sg_set_buf(reqctx->src, giv, ivsize); |
| 127 | eseqiv_chain(reqctx->src, osrc, vsrc == giv + ivsize); |
| 128 | |
| 129 | dst = reqctx->src; |
| 130 | if (osrc != odst) { |
| 131 | sg_init_table(reqctx->dst, 2); |
| 132 | sg_set_buf(reqctx->dst, giv, ivsize); |
| 133 | eseqiv_chain(reqctx->dst, odst, vdst == giv + ivsize); |
| 134 | |
| 135 | dst = reqctx->dst; |
| 136 | } |
| 137 | |
| 138 | ablkcipher_request_set_crypt(subreq, reqctx->src, dst, |
Herbert Xu | 46f8153 | 2008-04-29 21:57:01 +0800 | [diff] [blame] | 139 | req->creq.nbytes + ivsize, |
| 140 | req->creq.info); |
Herbert Xu | 806d183 | 2007-12-05 12:10:53 +1100 | [diff] [blame] | 141 | |
| 142 | memcpy(req->creq.info, ctx->salt, ivsize); |
| 143 | |
| 144 | len = ivsize; |
| 145 | if (ivsize > sizeof(u64)) { |
| 146 | memset(req->giv, 0, ivsize - sizeof(u64)); |
| 147 | len = sizeof(u64); |
| 148 | } |
| 149 | seq = cpu_to_be64(req->seq); |
| 150 | memcpy(req->giv + ivsize - len, &seq, len); |
| 151 | |
| 152 | err = crypto_ablkcipher_encrypt(subreq); |
| 153 | if (err) |
| 154 | goto out; |
| 155 | |
| 156 | eseqiv_complete2(req); |
| 157 | |
| 158 | out: |
| 159 | return err; |
| 160 | } |
| 161 | |
| 162 | static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req) |
| 163 | { |
| 164 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); |
| 165 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); |
| 166 | |
| 167 | spin_lock_bh(&ctx->lock); |
| 168 | if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first) |
| 169 | goto unlock; |
| 170 | |
| 171 | crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt; |
| 172 | get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv)); |
| 173 | |
| 174 | unlock: |
| 175 | spin_unlock_bh(&ctx->lock); |
| 176 | |
| 177 | return eseqiv_givencrypt(req); |
| 178 | } |
| 179 | |
| 180 | static int eseqiv_init(struct crypto_tfm *tfm) |
| 181 | { |
| 182 | struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); |
| 183 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); |
| 184 | unsigned long alignmask; |
| 185 | unsigned int reqsize; |
| 186 | |
| 187 | spin_lock_init(&ctx->lock); |
| 188 | |
| 189 | alignmask = crypto_tfm_ctx_alignment() - 1; |
| 190 | reqsize = sizeof(struct eseqiv_request_ctx); |
| 191 | |
| 192 | if (alignmask & reqsize) { |
| 193 | alignmask &= reqsize; |
| 194 | alignmask--; |
| 195 | } |
| 196 | |
| 197 | alignmask = ~alignmask; |
| 198 | alignmask &= crypto_ablkcipher_alignmask(geniv); |
| 199 | |
| 200 | reqsize += alignmask; |
| 201 | reqsize += crypto_ablkcipher_ivsize(geniv); |
| 202 | reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment()); |
| 203 | |
| 204 | ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx); |
| 205 | |
| 206 | tfm->crt_ablkcipher.reqsize = reqsize + |
| 207 | sizeof(struct ablkcipher_request); |
| 208 | |
| 209 | return skcipher_geniv_init(tfm); |
| 210 | } |
| 211 | |
| 212 | static struct crypto_template eseqiv_tmpl; |
| 213 | |
| 214 | static struct crypto_instance *eseqiv_alloc(struct rtattr **tb) |
| 215 | { |
| 216 | struct crypto_instance *inst; |
| 217 | int err; |
| 218 | |
| 219 | inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0); |
| 220 | if (IS_ERR(inst)) |
| 221 | goto out; |
| 222 | |
| 223 | err = -EINVAL; |
| 224 | if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize) |
| 225 | goto free_inst; |
| 226 | |
| 227 | inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first; |
| 228 | |
| 229 | inst->alg.cra_init = eseqiv_init; |
| 230 | inst->alg.cra_exit = skcipher_geniv_exit; |
| 231 | |
| 232 | inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx); |
| 233 | inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; |
| 234 | |
| 235 | out: |
| 236 | return inst; |
| 237 | |
| 238 | free_inst: |
| 239 | skcipher_geniv_free(inst); |
| 240 | inst = ERR_PTR(err); |
| 241 | goto out; |
| 242 | } |
| 243 | |
| 244 | static struct crypto_template eseqiv_tmpl = { |
| 245 | .name = "eseqiv", |
| 246 | .alloc = eseqiv_alloc, |
| 247 | .free = skcipher_geniv_free, |
| 248 | .module = THIS_MODULE, |
| 249 | }; |
| 250 | |
Herbert Xu | 5be5e66 | 2008-08-17 18:04:30 +1000 | [diff] [blame^] | 251 | static int __init eseqiv_module_init(void) |
Herbert Xu | 806d183 | 2007-12-05 12:10:53 +1100 | [diff] [blame] | 252 | { |
| 253 | return crypto_register_template(&eseqiv_tmpl); |
| 254 | } |
| 255 | |
Herbert Xu | 5be5e66 | 2008-08-17 18:04:30 +1000 | [diff] [blame^] | 256 | static void __exit eseqiv_module_exit(void) |
Herbert Xu | 806d183 | 2007-12-05 12:10:53 +1100 | [diff] [blame] | 257 | { |
| 258 | crypto_unregister_template(&eseqiv_tmpl); |
| 259 | } |
Herbert Xu | 5be5e66 | 2008-08-17 18:04:30 +1000 | [diff] [blame^] | 260 | |
| 261 | module_init(eseqiv_module_init); |
| 262 | module_exit(eseqiv_module_exit); |
| 263 | |
| 264 | MODULE_LICENSE("GPL"); |
| 265 | MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator"); |