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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 | spawn = aead_instance_ctx(inst); | |
157 | alg = crypto_spawn_aead_alg(spawn); | |
158 | ||
159 | err = -EINVAL; | |
160 | if (inst->alg.ivsize != sizeof(u64)) | |
161 | goto free_inst; | |
162 | ||
163 | inst->alg.encrypt = seqiv_aead_encrypt; | |
164 | inst->alg.decrypt = seqiv_aead_decrypt; | |
165 | ||
166 | inst->alg.init = aead_init_geniv; | |
167 | inst->alg.exit = aead_exit_geniv; | |
168 | ||
169 | inst->alg.base.cra_ctxsize = sizeof(struct aead_geniv_ctx); | |
170 | inst->alg.base.cra_ctxsize += inst->alg.ivsize; | |
171 | ||
172 | err = aead_register_instance(tmpl, inst); | |
173 | if (err) | |
174 | goto free_inst; | |
175 | ||
176 | out: | |
177 | return err; | |
178 | ||
179 | free_inst: | |
180 | aead_geniv_free(inst); | |
181 | goto out; | |
182 | } | |
183 | ||
184 | static int seqiv_create(struct crypto_template *tmpl, struct rtattr **tb) | |
185 | { | |
186 | struct crypto_attr_type *algt; | |
187 | ||
188 | algt = crypto_get_attr_type(tb); | |
189 | if (IS_ERR(algt)) | |
190 | return PTR_ERR(algt); | |
191 | ||
192 | if ((algt->type ^ CRYPTO_ALG_TYPE_AEAD) & CRYPTO_ALG_TYPE_MASK) | |
193 | return -EINVAL; | |
194 | ||
195 | return seqiv_aead_create(tmpl, tb); | |
196 | } | |
197 | ||
198 | static void seqiv_free(struct crypto_instance *inst) | |
199 | { | |
200 | aead_geniv_free(aead_instance(inst)); | |
201 | } | |
202 | ||
203 | static struct crypto_template seqiv_tmpl = { | |
204 | .name = "seqiv", | |
205 | .create = seqiv_create, | |
206 | .free = seqiv_free, | |
207 | .module = THIS_MODULE, | |
208 | }; | |
209 | ||
210 | static int __init seqiv_module_init(void) | |
211 | { | |
212 | return crypto_register_template(&seqiv_tmpl); | |
213 | } | |
214 | ||
215 | static void __exit seqiv_module_exit(void) | |
216 | { | |
217 | crypto_unregister_template(&seqiv_tmpl); | |
218 | } | |
219 | ||
220 | module_init(seqiv_module_init); | |
221 | module_exit(seqiv_module_exit); | |
222 | ||
223 | MODULE_LICENSE("GPL"); | |
224 | MODULE_DESCRIPTION("Sequence Number IV Generator"); | |
225 | MODULE_ALIAS_CRYPTO("seqiv"); |