blob: c7049231861f06f8339c3d3afa286b4a384b832d
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 |