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0a270321 HX |
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/skcipher.h> | |
17 | #include <linux/err.h> | |
18 | #include <linux/init.h> | |
19 | #include <linux/kernel.h> | |
20 | #include <linux/module.h> | |
21 | #include <linux/random.h> | |
22 | #include <linux/spinlock.h> | |
23 | #include <linux/string.h> | |
24 | ||
25 | struct seqiv_ctx { | |
26 | spinlock_t lock; | |
27 | u8 salt[] __attribute__ ((aligned(__alignof__(u32)))); | |
28 | }; | |
29 | ||
30 | static void seqiv_complete2(struct skcipher_givcrypt_request *req, int err) | |
31 | { | |
32 | struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); | |
33 | struct crypto_ablkcipher *geniv; | |
34 | ||
35 | if (err == -EINPROGRESS) | |
36 | return; | |
37 | ||
38 | if (err) | |
39 | goto out; | |
40 | ||
41 | geniv = skcipher_givcrypt_reqtfm(req); | |
42 | memcpy(req->creq.info, subreq->info, crypto_ablkcipher_ivsize(geniv)); | |
43 | ||
44 | out: | |
45 | kfree(subreq->info); | |
46 | } | |
47 | ||
48 | static void seqiv_complete(struct crypto_async_request *base, int err) | |
49 | { | |
50 | struct skcipher_givcrypt_request *req = base->data; | |
51 | ||
52 | seqiv_complete2(req, err); | |
53 | skcipher_givcrypt_complete(req, err); | |
54 | } | |
55 | ||
56 | static int seqiv_givencrypt(struct skcipher_givcrypt_request *req) | |
57 | { | |
58 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); | |
59 | struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); | |
60 | struct ablkcipher_request *subreq = skcipher_givcrypt_reqctx(req); | |
61 | crypto_completion_t complete; | |
62 | void *data; | |
63 | u8 *info; | |
64 | __be64 seq; | |
65 | unsigned int ivsize; | |
66 | unsigned int len; | |
67 | int err; | |
68 | ||
69 | ablkcipher_request_set_tfm(subreq, skcipher_geniv_cipher(geniv)); | |
70 | ||
71 | complete = req->creq.base.complete; | |
72 | data = req->creq.base.data; | |
73 | info = req->creq.info; | |
74 | ||
75 | ivsize = crypto_ablkcipher_ivsize(geniv); | |
76 | ||
77 | if (unlikely(!IS_ALIGNED((unsigned long)info, | |
78 | crypto_ablkcipher_alignmask(geniv) + 1))) { | |
79 | info = kmalloc(ivsize, req->creq.base.flags & | |
80 | CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL: | |
81 | GFP_ATOMIC); | |
82 | if (!info) | |
83 | return -ENOMEM; | |
84 | ||
85 | complete = seqiv_complete; | |
86 | data = req; | |
87 | } | |
88 | ||
89 | ablkcipher_request_set_callback(subreq, req->creq.base.flags, complete, | |
90 | data); | |
91 | ablkcipher_request_set_crypt(subreq, req->creq.src, req->creq.dst, | |
92 | req->creq.nbytes, info); | |
93 | ||
94 | len = ivsize; | |
95 | if (ivsize > sizeof(u64)) { | |
96 | memset(info, 0, ivsize - sizeof(u64)); | |
97 | len = sizeof(u64); | |
98 | } | |
99 | seq = cpu_to_be64(req->seq); | |
100 | memcpy(info + ivsize - len, &seq, len); | |
101 | crypto_xor(info, ctx->salt, ivsize); | |
102 | ||
103 | memcpy(req->giv, info, ivsize); | |
104 | ||
105 | err = crypto_ablkcipher_encrypt(subreq); | |
106 | if (unlikely(info != req->creq.info)) | |
107 | seqiv_complete2(req, err); | |
108 | return err; | |
109 | } | |
110 | ||
111 | static int seqiv_givencrypt_first(struct skcipher_givcrypt_request *req) | |
112 | { | |
113 | struct crypto_ablkcipher *geniv = skcipher_givcrypt_reqtfm(req); | |
114 | struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); | |
115 | ||
116 | spin_lock_bh(&ctx->lock); | |
117 | if (crypto_ablkcipher_crt(geniv)->givencrypt != seqiv_givencrypt_first) | |
118 | goto unlock; | |
119 | ||
120 | crypto_ablkcipher_crt(geniv)->givencrypt = seqiv_givencrypt; | |
121 | get_random_bytes(ctx->salt, crypto_ablkcipher_ivsize(geniv)); | |
122 | ||
123 | unlock: | |
124 | spin_unlock_bh(&ctx->lock); | |
125 | ||
126 | return seqiv_givencrypt(req); | |
127 | } | |
128 | ||
129 | static int seqiv_init(struct crypto_tfm *tfm) | |
130 | { | |
131 | struct crypto_ablkcipher *geniv = __crypto_ablkcipher_cast(tfm); | |
132 | struct seqiv_ctx *ctx = crypto_ablkcipher_ctx(geniv); | |
133 | ||
134 | spin_lock_init(&ctx->lock); | |
135 | ||
136 | tfm->crt_ablkcipher.reqsize = sizeof(struct ablkcipher_request); | |
137 | ||
138 | return skcipher_geniv_init(tfm); | |
139 | } | |
140 | ||
141 | static struct crypto_template seqiv_tmpl; | |
142 | ||
143 | static struct crypto_instance *seqiv_alloc(struct rtattr **tb) | |
144 | { | |
145 | struct crypto_instance *inst; | |
146 | ||
147 | inst = skcipher_geniv_alloc(&seqiv_tmpl, tb, 0, 0); | |
148 | if (IS_ERR(inst)) | |
149 | goto out; | |
150 | ||
151 | inst->alg.cra_ablkcipher.givencrypt = seqiv_givencrypt_first; | |
152 | ||
153 | inst->alg.cra_init = seqiv_init; | |
154 | inst->alg.cra_exit = skcipher_geniv_exit; | |
155 | ||
156 | inst->alg.cra_alignmask |= __alignof__(u32) - 1; | |
157 | ||
158 | inst->alg.cra_ctxsize = sizeof(struct seqiv_ctx); | |
159 | inst->alg.cra_ctxsize += inst->alg.cra_ablkcipher.ivsize; | |
160 | ||
161 | out: | |
162 | return inst; | |
163 | } | |
164 | ||
165 | static struct crypto_template seqiv_tmpl = { | |
166 | .name = "seqiv", | |
167 | .alloc = seqiv_alloc, | |
168 | .free = skcipher_geniv_free, | |
169 | .module = THIS_MODULE, | |
170 | }; | |
171 | ||
172 | static int __init seqiv_module_init(void) | |
173 | { | |
174 | return crypto_register_template(&seqiv_tmpl); | |
175 | } | |
176 | ||
177 | static void __exit seqiv_module_exit(void) | |
178 | { | |
179 | crypto_unregister_template(&seqiv_tmpl); | |
180 | } | |
181 | ||
182 | module_init(seqiv_module_init); | |
183 | module_exit(seqiv_module_exit); | |
184 | ||
185 | MODULE_LICENSE("GPL"); | |
186 | MODULE_DESCRIPTION("Sequence Number IV Generator"); |