Root/
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/rng.h> |
20 | #include <crypto/scatterwalk.h> |
21 | #include <linux/err.h> |
22 | #include <linux/init.h> |
23 | #include <linux/kernel.h> |
24 | #include <linux/mm.h> |
25 | #include <linux/module.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, |
139 | req->creq.nbytes + ivsize, |
140 | req->creq.info); |
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 | if (giv != req->giv) |
157 | eseqiv_complete2(req); |
158 | |
159 | out: |
160 | return err; |
161 | } |
162 | |
163 | static int eseqiv_givencrypt_first(struct skcipher_givcrypt_request *req) |
164 | { |
165 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); |
166 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); |
167 | int err = 0; |
168 | |
169 | spin_lock_bh(&ctx->lock); |
170 | if (crypto_ablkcipher_crt(geniv)->givencrypt != eseqiv_givencrypt_first) |
171 | goto unlock; |
172 | |
173 | crypto_ablkcipher_crt(geniv)->givencrypt = eseqiv_givencrypt; |
174 | err = crypto_rng_get_bytes(crypto_default_rng, ctx->salt, |
175 | crypto_ablkcipher_ivsize(geniv)); |
176 | |
177 | unlock: |
178 | spin_unlock_bh(&ctx->lock); |
179 | |
180 | if (err) |
181 | return err; |
182 | |
183 | return eseqiv_givencrypt(req); |
184 | } |
185 | |
186 | static int eseqiv_init(struct crypto_tfm *tfm) |
187 | { |
188 | struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); |
189 | struct eseqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); |
190 | unsigned long alignmask; |
191 | unsigned int reqsize; |
192 | |
193 | spin_lock_init(&ctx->lock); |
194 | |
195 | alignmask = crypto_tfm_ctx_alignment() - 1; |
196 | reqsize = sizeof(struct eseqiv_request_ctx); |
197 | |
198 | if (alignmask & reqsize) { |
199 | alignmask &= reqsize; |
200 | alignmask--; |
201 | } |
202 | |
203 | alignmask = ~alignmask; |
204 | alignmask &= crypto_ablkcipher_alignmask(geniv); |
205 | |
206 | reqsize += alignmask; |
207 | reqsize += crypto_ablkcipher_ivsize(geniv); |
208 | reqsize = ALIGN(reqsize, crypto_tfm_ctx_alignment()); |
209 | |
210 | ctx->reqoff = reqsize - sizeof(struct eseqiv_request_ctx); |
211 | |
212 | tfm->crt_ablkcipher.reqsize = reqsize + |
213 | sizeof(struct ablkcipher_request); |
214 | |
215 | return skcipher_geniv_init(tfm); |
216 | } |
217 | |
218 | static struct crypto_template eseqiv_tmpl; |
219 | |
220 | static struct crypto_instance *eseqiv_alloc(struct rtattr **tb) |
221 | { |
222 | struct crypto_instance *inst; |
223 | int err; |
224 | |
225 | err = crypto_get_default_rng(); |
226 | if (err) |
227 | return ERR_PTR(err); |
228 | |
229 | inst = skcipher_geniv_alloc(&eseqiv_tmpl, tb, 0, 0); |
230 | if (IS_ERR(inst)) |
231 | goto put_rng; |
232 | |
233 | err = -EINVAL; |
234 | if (inst->alg.cra_ablkcipher.ivsize != inst->alg.cra_blocksize) |
235 | goto free_inst; |
236 | |
237 | inst->alg.cra_ablkcipher.givencrypt = eseqiv_givencrypt_first; |
238 | |
239 | inst->alg.cra_init = eseqiv_init; |
240 | inst->alg.cra_exit = skcipher_geniv_exit; |
241 | |
242 | inst->alg.cra_ctxsize = sizeof(struct eseqiv_ctx); |
243 | inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; |
244 | |
245 | out: |
246 | return inst; |
247 | |
248 | free_inst: |
249 | skcipher_geniv_free(inst); |
250 | inst = ERR_PTR(err); |
251 | put_rng: |
252 | crypto_put_default_rng(); |
253 | goto out; |
254 | } |
255 | |
256 | static void eseqiv_free(struct crypto_instance *inst) |
257 | { |
258 | skcipher_geniv_free(inst); |
259 | crypto_put_default_rng(); |
260 | } |
261 | |
262 | static struct crypto_template eseqiv_tmpl = { |
263 | .name = "eseqiv", |
264 | .alloc = eseqiv_alloc, |
265 | .free = eseqiv_free, |
266 | .module = THIS_MODULE, |
267 | }; |
268 | |
269 | static int __init eseqiv_module_init(void) |
270 | { |
271 | return crypto_register_template(&eseqiv_tmpl); |
272 | } |
273 | |
274 | static void __exit eseqiv_module_exit(void) |
275 | { |
276 | crypto_unregister_template(&eseqiv_tmpl); |
277 | } |
278 | |
279 | module_init(eseqiv_module_init); |
280 | module_exit(eseqiv_module_exit); |
281 | |
282 | MODULE_LICENSE("GPL"); |
283 | MODULE_DESCRIPTION("Encrypted Sequence Number IV Generator"); |
284 |
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