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Linux/crypto/seqiv.c

  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                 SKCIPHER_REQUEST_ON_STACK(nreq, ctx->sknull);
 77 
 78                 skcipher_request_set_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 = kmalloc(ivsize, req->base.flags &
 93                                        CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL:
 94                                                                   GFP_ATOMIC);
 95                 if (!info)
 96                         return -ENOMEM;
 97 
 98                 memcpy(info, req->iv, ivsize);
 99                 compl = seqiv_aead_encrypt_complete;
100                 data = req;
101         }
102 
103         aead_request_set_callback(subreq, req->base.flags, compl, data);
104         aead_request_set_crypt(subreq, req->dst, req->dst,
105                                req->cryptlen - ivsize, info);
106         aead_request_set_ad(subreq, req->assoclen + ivsize);
107 
108         crypto_xor(info, ctx->salt, ivsize);
109         scatterwalk_map_and_copy(info, req->dst, req->assoclen, ivsize, 1);
110 
111         err = crypto_aead_encrypt(subreq);
112         if (unlikely(info != req->iv))
113                 seqiv_aead_encrypt_complete2(req, err);
114         return err;
115 }
116 
117 static int seqiv_aead_decrypt(struct aead_request *req)
118 {
119         struct crypto_aead *geniv = crypto_aead_reqtfm(req);
120         struct aead_geniv_ctx *ctx = crypto_aead_ctx(geniv);
121         struct aead_request *subreq = aead_request_ctx(req);
122         crypto_completion_t compl;
123         void *data;
124         unsigned int ivsize = 8;
125 
126         if (req->cryptlen < ivsize + crypto_aead_authsize(geniv))
127                 return -EINVAL;
128 
129         aead_request_set_tfm(subreq, ctx->child);
130 
131         compl = req->base.complete;
132         data = req->base.data;
133 
134         aead_request_set_callback(subreq, req->base.flags, compl, data);
135         aead_request_set_crypt(subreq, req->src, req->dst,
136                                req->cryptlen - ivsize, req->iv);
137         aead_request_set_ad(subreq, req->assoclen + ivsize);
138 
139         scatterwalk_map_and_copy(req->iv, req->src, req->assoclen, ivsize, 0);
140 
141         return crypto_aead_decrypt(subreq);
142 }
143 
144 static int seqiv_aead_create(struct crypto_template *tmpl, struct rtattr **tb)
145 {
146         struct aead_instance *inst;
147         struct crypto_aead_spawn *spawn;
148         struct aead_alg *alg;
149         int err;
150 
151         inst = aead_geniv_alloc(tmpl, tb, 0, 0);
152 
153         if (IS_ERR(inst))
154                 return PTR_ERR(inst);
155 
156         inst->alg.base.cra_alignmask |= __alignof__(u32) - 1;
157 
158         spawn = aead_instance_ctx(inst);
159         alg = crypto_spawn_aead_alg(spawn);
160 
161         err = -EINVAL;
162         if (inst->alg.ivsize != sizeof(u64))
163                 goto free_inst;
164 
165         inst->alg.encrypt = seqiv_aead_encrypt;
166         inst->alg.decrypt = seqiv_aead_decrypt;
167 
168         inst->alg.init = aead_init_geniv;
169         inst->alg.exit = aead_exit_geniv;
170 
171         inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx);
172         inst->alg.base.cra_ctxsize += inst->alg.ivsize;
173 
174         err = aead_register_instance(tmpl, inst);
175         if (err)
176                 goto free_inst;
177 
178 out:
179         return err;
180 
181 free_inst:
182         aead_geniv_free(inst);
183         goto out;
184 }
185 
186 static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb)
187 {
188         struct crypto_attr_type *algt;
189 
190         algt = crypto_get_attr_type(tb);
191         if (IS_ERR(algt))
192                 return PTR_ERR(algt);
193 
194         if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK)
195                 return -EINVAL;
196 
197         return seqiv_aead_create(tmpl, tb);
198 }
199 
200 static void seqiv_free(struct crypto_instance *inst)
201 {
202         aead_geniv_free(aead_instance(inst));
203 }
204 
205 static struct crypto_template seqiv_tmpl = {
206         .name = "seqiv",
207         .create = seqiv_create,
208         .free = seqiv_free,
209         .module = THIS_MODULE,
210 };
211 
212 static int __init seqiv_module_init(void)
213 {
214         return crypto_register_template(&seqiv_tmpl);
215 }
216 
217 static void __exit seqiv_module_exit(void)
218 {
219         crypto_unregister_template(&seqiv_tmpl);
220 }
221 
222 module_init(seqiv_module_init);
223 module_exit(seqiv_module_exit);
224 
225 MODULE_LICENSE("GPL");
226 MODULE_DESCRIPTION("Sequence Number IV Generator");
227 MODULE_ALIAS_CRYPTO("seqiv");
228 

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