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authorHerbert Xu <herbert@gondor.apana.org.au>2007-11-30 05:38:37 -0500
committerHerbert Xu <herbert@gondor.apana.org.au>2008-01-10 16:16:48 -0500
commit0a270321dbf948963aeb0e8382fe17d2c2eb3771 (patch)
treebdb6c12f88bd02b62853ff6bf26bf9d4a736fdbd /crypto/seqiv.c
parent45d44eb56ad197cfccb8f84b5df64abff8b7cb96 (diff)
[CRYPTO] seqiv: Add Sequence Number IV Generator
This generator generates an IV based on a sequence number by xoring it with a salt. This algorithm is mainly useful for CTR and similar modes. This patch also sets it as the default IV generator for ctr. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto/seqiv.c')
-rw-r--r--crypto/seqiv.c186
1 files changed, 186 insertions, 0 deletions
diff --git a/crypto/seqiv.c b/crypto/seqiv.c
new file mode 100644
index 000000000000..9c2d80d77a0a
--- /dev/null
+++ b/crypto/seqiv.c
@@ -0,0 +1,186 @@
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
25struct seqiv_ctx {
26 spinlock_t lock;
27 u8 salt[] __attribute__ ((aligned(__alignof__(u32))));
28};
29
30static 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
44out:
45 kfree(subreq->info);
46}
47
48static 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
56static 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
111static 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
123unlock:
124 spin_unlock_bh(&ctx->lock);
125
126 return seqiv_givencrypt(req);
127}
128
129static 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
141static struct crypto_template seqiv_tmpl;
142
143static 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
161out:
162 return inst;
163}
164
165static struct crypto_template seqiv_tmpl = {
166 .name = "seqiv",
167 .alloc = seqiv_alloc,
168 .free = skcipher_geniv_free,
169 .module = THIS_MODULE,
170};
171
172static int __init seqiv_module_init(void)
173{
174 return crypto_register_template(&seqiv_tmpl);
175}
176
177static void __exit seqiv_module_exit(void)
178{
179 crypto_unregister_template(&seqiv_tmpl);
180}
181
182module_init(seqiv_module_init);
183module_exit(seqiv_module_exit);
184
185MODULE_LICENSE("GPL");
186MODULE_DESCRIPTION("Sequence Number IV Generator");