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
26static void seqiv_free(struct crypto_instance *inst);
27
28static 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
42out:
43 kzfree(subreq->iv);
44}
45
46static 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
55static 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
116static 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
143static 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
170out:
171 return err;
172
173free_inst:
174 aead_geniv_free(inst);
175 goto out;
176}
177
178static 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
192static void seqiv_free(struct crypto_instance *inst)
193{
194 aead_geniv_free(aead_instance(inst));
195}
196
197static struct crypto_template seqiv_tmpl = {
198 .name = "seqiv",
199 .create = seqiv_create,
200 .free = seqiv_free,
201 .module = THIS_MODULE,
202};
203
204static int __init seqiv_module_init(void)
205{
206 return crypto_register_template(&seqiv_tmpl);
207}
208
209static void __exit seqiv_module_exit(void)
210{
211 crypto_unregister_template(&seqiv_tmpl);
212}
213
214module_init(seqiv_module_init);
215module_exit(seqiv_module_exit);
216
217MODULE_LICENSE("GPL");
218MODULE_DESCRIPTION("Sequence Number IV Generator");
219MODULE_ALIAS_CRYPTO("seqiv");
220