1 /* 2 * seqiv: Sequence Number IV Generator 3 * 4 * This generator generates an IV based on a sequence number by xoring it 5 * with a salt. This algorithm is mainly useful for CTR and similar modes. 6 * 7 * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> 8 * 9 * This program is free software; you can redistribute it and/or modify it 10 * under the terms of the GNU General Public License as published by the Free 11 * Software Foundation; either version 2 of the License, or (at your option) 12 * any later version. 13 * 14 */ 15 16 #include <crypto/internal/geniv.h> 17 #include <crypto/scatterwalk.h> 18 #include <crypto/skcipher.h> 19 #include <linux/err.h> 20 #include <linux/init.h> 21 #include <linux/kernel.h> 22 #include <linux/module.h> 23 #include <linux/slab.h> 24 #include <linux/string.h> 25 26 static void seqiv_free(struct crypto_instance *inst); 27 28 static void seqiv_aead_encrypt_complete2(struct aead_request *req, int err) 29 { 30 struct aead_request *subreq = aead_request_ctx(req); 31 struct crypto_aead *geniv; 32 33 if (err == -EINPROGRESS) 34 return; 35 36 if (err) 37 goto out; 38 39 geniv = crypto_aead_reqtfm(req); 40 memcpy(req->iv, subreq->iv, crypto_aead_ivsize(geniv)); 41 42 out: 43 kzfree(subreq->iv); 44 } 45 46 static void seqiv_aead_encrypt_complete(struct crypto_async_request *base, 47 int err) 48 { 49 struct aead_request *req = base->data; 50 51 seqiv_aead_encrypt_complete2(req, err); 52 aead_request_complete(req, err); 53 } 54 55 static int seqiv_aead_encrypt(struct aead_request *req) 56 { 57 struct crypto_aead *geniv = crypto_aead_reqtfm(req); 58 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); 59 struct aead_request *subreq = aead_request_ctx(req); 60 crypto_completion_t compl; 61 void *data; 62 u8 *info; 63 unsigned int ivsize = 8; 64 int err; 65 66 if (req->cryptlen < ivsize) 67 return -EINVAL; 68 69 aead_request_set_tfm(subreq, ctx->child); 70 71 compl = req->base.complete; 72 data = req->base.data; 73 info = req->iv; 74 75 if (req->src != req->dst) { 76 SYNC_SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull); 77 78 skcipher_request_set_sync_tfm(nreq, ctx->sknull); 79 skcipher_request_set_callback(nreq, req->base.flags, 80 NULL, NULL); 81 skcipher_request_set_crypt(nreq, req->src, req->dst, 82 req->assoclen + req->cryptlen, 83 NULL); 84 85 err = crypto_skcipher_encrypt(nreq); 86 if (err) 87 return err; 88 } 89 90 if (unlikely(!IS_ALIGNED((unsigned long)info, 91 crypto_aead_alignmask(geniv) + 1))) { 92 info = kmemdup(req->iv, ivsize, req->base.flags & 93 CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL : 94 GFP_ATOMIC); 95 if (!info) 96 return -ENOMEM; 97 98 compl = seqiv_aead_encrypt_complete; 99 data = req; 100 } 101 102 aead_request_set_callback(subreq, req->base.flags, compl, data); 103 aead_request_set_crypt(subreq, req->dst, req->dst, 104 req->cryptlen - ivsize, info); 105 aead_request_set_ad(subreq, req->assoclen + ivsize); 106 107 crypto_xor(info, ctx->salt, ivsize); 108 scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1); 109 110 err = crypto_aead_encrypt(subreq); 111 if (unlikely(info != req->iv)) 112 seqiv_aead_encrypt_complete2(req, err); 113 return err; 114 } 115 116 static int seqiv_aead_decrypt(struct aead_request *req) 117 { 118 struct crypto_aead *geniv = crypto_aead_reqtfm(req); 119 struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv); 120 struct aead_request *subreq = aead_request_ctx(req); 121 crypto_completion_t compl; 122 void *data; 123 unsigned int ivsize = 8; 124 125 if (req->cryptlen < ivsize + crypto_aead_authsize(geniv)) 126 return -EINVAL; 127 128 aead_request_set_tfm(subreq, ctx->child); 129 130 compl = req->base.complete; 131 data = req->base.data; 132 133 aead_request_set_callback(subreq, req->base.flags, compl, data); 134 aead_request_set_crypt(subreq, req->src, req->dst, 135 req->cryptlen - ivsize, req->iv); 136 aead_request_set_ad(subreq, req->assoclen + ivsize); 137 138 scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0); 139 140 return crypto_aead_decrypt(subreq); 141 } 142 143 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb) 144 { 145 struct aead_instance *inst; 146 int err; 147 148 inst = aead_geniv_alloc(tmpl, tb, 0, 0); 149 150 if (IS_ERR(inst)) 151 return PTR_ERR(inst); 152 153 err = -EINVAL; 154 if (inst->alg.ivsize != sizeof(u64)) 155 goto free_inst; 156 157 inst->alg.encrypt = seqiv_aead_encrypt; 158 inst->alg.decrypt = seqiv_aead_decrypt; 159 160 inst->alg.init = aead_init_geniv; 161 inst->alg.exit = aead_exit_geniv; 162 163 inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx); 164 inst->alg.base.cra_ctxsize += inst->alg.ivsize; 165 166 err = aead_register_instance(tmpl, inst); 167 if (err) 168 goto free_inst; 169 170 out: 171 return err; 172 173 free_inst: 174 aead_geniv_free(inst); 175 goto out; 176 } 177 178 static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb) 179 { 180 struct crypto_attr_type *algt; 181 182 algt = crypto_get_attr_type(tb); 183 if (IS_ERR(algt)) 184 return PTR_ERR(algt); 185 186 if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) 187 return -EINVAL; 188 189 return seqiv_aead_create(tmpl, tb); 190 } 191 192 static void seqiv_free(struct crypto_instance *inst) 193 { 194 aead_geniv_free(aead_instance(inst)); 195 } 196 197 static struct crypto_template seqiv_tmpl = { 198 .name = "seqiv", 199 .create = seqiv_create, 200 .free = seqiv_free, 201 .module = THIS_MODULE, 202 }; 203 204 static int __init seqiv_module_init(void) 205 { 206 return crypto_register_template(&seqiv_tmpl); 207 } 208 209 static void __exit seqiv_module_exit(void) 210 { 211 crypto_unregister_template(&seqiv_tmpl); 212 } 213 214 subsys_initcall(seqiv_module_init); 215 module_exit(seqiv_module_exit); 216 217 MODULE_LICENSE("GPL"); 218 MODULE_DESCRIPTION("Sequence Number IV Generator"); 219 MODULE_ALIAS_CRYPTO("seqiv"); 220