Commit | Line | Data |
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806d183a HX |
1 | /* |
2 | * eseqiv: Encrypted Sequence Number IV Generator | |
3 | * | |
4 | * This generator generates an IV based on a sequence number by xoring it | |
5 | * with a salt and then encrypting it with the same key as used to encrypt | |
6 | * the plain text. This algorithm requires that the block size be equal | |
7 | * to the IV size. It is mainly useful for CBC. | |
8 | * | |
9 | * Copyright (c) 2007 Herbert Xu <herbert@gondor.apana.org.au> | |
10 | * | |
11 | * This program is free software; you can redistribute it and/or modify it | |
12 | * under the terms of the GNU General Public License as published by the Free | |
13 | * Software Foundation; either version 2 of the License, or (at your option) | |
14 | * any later version. | |
15 | * | |
16 | */ | |
17 | ||
18 | #include <crypto/internal/skcipher.h> | |
19 | #include <crypto/scatterwalk.h> | |
20 | #include <linux/err.h> | |
21 | #include <linux/init.h> | |
22 | #include <linux/kernel.h> | |
23 | #include <linux/mm.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/random.h> | |
26 | #include <linux/scatterlist.h> | |
27 | #include <linux/spinlock.h> | |
28 | #include <linux/string.h> | |
29 | ||
30 | struct eseqiv_request_ctx { | |
31 | struct scatterlist src[2]; | |
32 | struct scatterlist dst[2]; | |
33 | char tail[]; | |
34 | }; | |
35 | ||
36 | struct eseqiv_ctx { | |
37 | spinlock_t lock; | |
38 | unsigned int reqoff; | |
39 | char salt[]; | |
40 | }; | |
41 | ||
42 | static void eseqiv_complete2(struct skcipher_givcrypt_request *req) | |
43 | { | |
44 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); | |
45 | struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req); | |
46 | ||
47 | memcpy(req->giv, PTR_ALIGN((u8 *)reqctx->tail, | |
48 | crypto_ablkcipher_alignmask(geniv) + 1), | |
49 | crypto_ablkcipher_ivsize(geniv)); | |
50 | } | |
51 | ||
52 | static void eseqiv_complete(struct crypto_async_request *base, int err) | |
53 | { | |
54 | struct skcipher_givcrypt_request *req = base->data; | |
55 | ||
56 | if (err) | |
57 | goto out; | |
58 | ||
59 | eseqiv_complete2(req); | |
60 | ||
61 | out: | |
62 | skcipher_givcrypt_complete(req, err); | |
63 | } | |
64 | ||
65 | static void eseqiv_chain(struct scatterlist *head, struct scatterlist *sg, | |
66 | int chain) | |
67 | { | |
68 | if (chain) { | |
69 | head->length += sg->length; | |
70 | sg = scatterwalk_sg_next(sg); | |
71 | } | |
72 | ||
73 | if (sg) | |
74 | scatterwalk_sg_chain(head, 2, sg); | |
75 | else | |
76 | sg_mark_end(head); | |
77 | } | |
78 | ||
79 | static int eseqiv_givencrypt(struct skcipher_givcrypt_request *req) | |
80 | { | |
81 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); | |
82 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); | |
83 | struct eseqiv_request_ctx *reqctx = skcipher_givcrypt_reqctx(req); | |
84 | struct ablkcipher_request *subreq; | |
85 | crypto_completion_t complete; | |
86 | void *data; | |
87 | struct scatterlist *osrc, *odst; | |
88 | struct scatterlist *dst; | |
89 | struct page *srcp; | |
90 | struct page *dstp; | |
91 | u8 *giv; | |
92 | u8 *vsrc; | |
93 | u8 *vdst; | |
94 | __be64 seq; | |
95 | unsigned int ivsize; | |
96 | unsigned int len; | |
97 | int err; | |
98 | ||
99 | subreq = (void *)(reqctx->tail + ctx->reqoff); | |
100 | ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); | |
101 | ||
102 | giv = req->giv; | |
103 | complete = req->creq.base.complete; | |
104 | data = req->creq.base.data; | |
105 | ||
106 | osrc = req->creq.src; | |
107 | odst = req->creq.dst; | |
108 | srcp = sg_page(osrc); | |
109 | dstp = sg_page(odst); | |
110 | vsrc = PageHighMem(srcp) ? NULL : page_address(srcp) + osrc->offset; | |
111 | vdst = PageHighMem(dstp) ? NULL : page_address(dstp) + odst->offset; | |
112 | ||
113 | ivsize = crypto_ablkcipher_ivsize(geniv); | |
114 | ||
115 | if (vsrc != giv + ivsize && vdst != giv + ivsize) { | |
116 | giv = PTR_ALIGN((u8 *)reqctx->tail, | |
117 | crypto_ablkcipher_alignmask(geniv) + 1); | |
118 | complete = eseqiv_complete; | |
119 | data = req; | |
120 | } | |
121 | ||
122 | ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete, | |
123 | data); | |
124 | ||
125 | sg_init_table(reqctx->src, 2); | |
126 | sg_set_buf(reqctx->src, giv, ivsize); | |
127 | eseqiv_chain(reqctx->src, osrc, vsrc == giv + ivsize); | |
128 | ||
129 | dst = reqctx->src; | |
130 | if (osrc != odst) { | |
131 | sg_init_table(reqctx->dst, 2); | |
132 | sg_set_buf(reqctx->dst, giv, ivsize); | |
133 | eseqiv_chain(reqctx->dst, odst, vdst == giv + ivsize); | |
134 | ||
135 | dst = reqctx->dst; | |
136 | } | |
137 | ||
138 | ablkcipher_request_set_crypt(subreq, reqctx->src, dst, | |
46f8153c HX |
139 | req->creq.nbytes + ivsize, |
140 | req->creq.info); | |
806d183a HX |
141 | |
142 | memcpy(req->creq.info, ctx->salt, ivsize); | |
143 | ||
144 | len = ivsize; | |
145 | if (ivsize > sizeof(u64)) { | |
146 | memset(req->giv, 0, ivsize - sizeof(u64)); | |
147 | len = sizeof(u64); | |
148 | } | |
149 | seq = cpu_to_be64(req->seq); | |
150 | memcpy(req->giv + ivsize - len, &seq, len); | |
151 | ||
152 | err = crypto_ablkcipher_encrypt(subreq); | |
153 | if (err) | |
154 | goto out; | |
155 | ||
156 | eseqiv_complete2(req); | |
157 | ||
158 | out: | |
159 | return err; | |
160 | } | |
161 | ||
162 | static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req) | |
163 | { | |
164 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); | |
165 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); | |
166 | ||
167 | spin_lock_bh(&ctx->lock); | |
168 | if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first) | |
169 | goto unlock; | |
170 | ||
171 | crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt; | |
172 | get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv)); | |
173 | ||
174 | unlock: | |
175 | spin_unlock_bh(&ctx->lock); | |
176 | ||
177 | return eseqiv_givencrypt(req); | |
178 | } | |
179 | ||
180 | static int eseqiv_init(struct crypto_tfm *tfm) | |
181 | { | |
182 | struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); | |
183 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); | |
184 | unsigned long alignmask; | |
185 | unsigned int reqsize; | |
186 | ||
187 | spin_lock_init(&ctx->lock); | |
188 | ||
189 | alignmask = crypto_tfm_ctx_alignment() - 1; | |
190 | reqsize = sizeof(struct eseqiv_request_ctx); | |
191 | ||
192 | if (alignmask & reqsize) { | |
193 | alignmask &= reqsize; | |
194 | alignmask--; | |
195 | } | |
196 | ||
197 | alignmask = ~alignmask; | |
198 | alignmask &= crypto_ablkcipher_alignmask(geniv); | |
199 | ||
200 | reqsize += alignmask; | |
201 | reqsize += crypto_ablkcipher_ivsize(geniv); | |
202 | reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment()); | |
203 | ||
204 | ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx); | |
205 | ||
206 | tfm->crt_ablkcipher.reqsize = reqsize + | |
207 | sizeof(struct ablkcipher_request); | |
208 | ||
209 | return skcipher_geniv_init(tfm); | |
210 | } | |
211 | ||
212 | static struct crypto_template eseqiv_tmpl; | |
213 | ||
214 | static struct crypto_instance *eseqiv_alloc(struct rtattr **tb) | |
215 | { | |
216 | struct crypto_instance *inst; | |
217 | int err; | |
218 | ||
219 | inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0); | |
220 | if (IS_ERR(inst)) | |
221 | goto out; | |
222 | ||
223 | err = -EINVAL; | |
224 | if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize) | |
225 | goto free_inst; | |
226 | ||
227 | inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first; | |
228 | ||
229 | inst->alg.cra_init = eseqiv_init; | |
230 | inst->alg.cra_exit = skcipher_geniv_exit; | |
231 | ||
232 | inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx); | |
233 | inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; | |
234 | ||
235 | out: | |
236 | return inst; | |
237 | ||
238 | free_inst: | |
239 | skcipher_geniv_free(inst); | |
240 | inst = ERR_PTR(err); | |
241 | goto out; | |
242 | } | |
243 | ||
244 | static struct crypto_template eseqiv_tmpl = { | |
245 | .name = "eseqiv", | |
246 | .alloc = eseqiv_alloc, | |
247 | .free = skcipher_geniv_free, | |
248 | .module = THIS_MODULE, | |
249 | }; | |
250 | ||
76fc60a2 | 251 | int __init eseqiv_module_init(void) |
806d183a HX |
252 | { |
253 | return crypto_register_template(&eseqiv_tmpl); | |
254 | } | |
255 | ||
76fc60a2 | 256 | void __exit eseqiv_module_exit(void) |
806d183a HX |
257 | { |
258 | crypto_unregister_template(&eseqiv_tmpl); | |
259 | } |