[CRYPTO] Don't check for NULL before kfree()
[linux-2.6.git] / crypto / hmac.c
1 /*
2  * Cryptographic API.
3  *
4  * HMAC: Keyed-Hashing for Message Authentication (RFC2104).
5  *
6  * Copyright (c) 2002 James Morris <jmorris@intercode.com.au>
7  *
8  * The HMAC implementation is derived from USAGI.
9  * Copyright (c) 2002 Kazunori Miyazawa <miyazawa@linux-ipv6.org> / USAGI
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 #include <linux/crypto.h>
18 #include <linux/mm.h>
19 #include <linux/highmem.h>
20 #include <linux/slab.h>
21 #include <asm/scatterlist.h>
22 #include "internal.h"
23
24 static void hash_key(struct crypto_tfm *tfm, u8 *key, unsigned int keylen)
25 {
26         struct scatterlist tmp;
27         
28         tmp.page = virt_to_page(key);
29         tmp.offset = offset_in_page(key);
30         tmp.length = keylen;
31         crypto_digest_digest(tfm, &tmp, 1, key);
32                 
33 }
34
35 int crypto_alloc_hmac_block(struct crypto_tfm *tfm)
36 {
37         int ret = 0;
38
39         BUG_ON(!crypto_tfm_alg_blocksize(tfm));
40         
41         tfm->crt_digest.dit_hmac_block = kmalloc(crypto_tfm_alg_blocksize(tfm),
42                                                  GFP_KERNEL);
43         if (tfm->crt_digest.dit_hmac_block == NULL)
44                 ret = -ENOMEM;
45
46         return ret;
47                 
48 }
49
50 void crypto_free_hmac_block(struct crypto_tfm *tfm)
51 {
52         kfree(tfm->crt_digest.dit_hmac_block);
53 }
54
55 void crypto_hmac_init(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen)
56 {
57         unsigned int i;
58         struct scatterlist tmp;
59         char *ipad = tfm->crt_digest.dit_hmac_block;
60         
61         if (*keylen > crypto_tfm_alg_blocksize(tfm)) {
62                 hash_key(tfm, key, *keylen);
63                 *keylen = crypto_tfm_alg_digestsize(tfm);
64         }
65
66         memset(ipad, 0, crypto_tfm_alg_blocksize(tfm));
67         memcpy(ipad, key, *keylen);
68
69         for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++)
70                 ipad[i] ^= 0x36;
71
72         tmp.page = virt_to_page(ipad);
73         tmp.offset = offset_in_page(ipad);
74         tmp.length = crypto_tfm_alg_blocksize(tfm);
75         
76         crypto_digest_init(tfm);
77         crypto_digest_update(tfm, &tmp, 1);
78 }
79
80 void crypto_hmac_update(struct crypto_tfm *tfm,
81                         struct scatterlist *sg, unsigned int nsg)
82 {
83         crypto_digest_update(tfm, sg, nsg);
84 }
85
86 void crypto_hmac_final(struct crypto_tfm *tfm, u8 *key,
87                        unsigned int *keylen, u8 *out)
88 {
89         unsigned int i;
90         struct scatterlist tmp;
91         char *opad = tfm->crt_digest.dit_hmac_block;
92         
93         if (*keylen > crypto_tfm_alg_blocksize(tfm)) {
94                 hash_key(tfm, key, *keylen);
95                 *keylen = crypto_tfm_alg_digestsize(tfm);
96         }
97
98         crypto_digest_final(tfm, out);
99
100         memset(opad, 0, crypto_tfm_alg_blocksize(tfm));
101         memcpy(opad, key, *keylen);
102                 
103         for (i = 0; i < crypto_tfm_alg_blocksize(tfm); i++)
104                 opad[i] ^= 0x5c;
105
106         tmp.page = virt_to_page(opad);
107         tmp.offset = offset_in_page(opad);
108         tmp.length = crypto_tfm_alg_blocksize(tfm);
109
110         crypto_digest_init(tfm);
111         crypto_digest_update(tfm, &tmp, 1);
112         
113         tmp.page = virt_to_page(out);
114         tmp.offset = offset_in_page(out);
115         tmp.length = crypto_tfm_alg_digestsize(tfm);
116         
117         crypto_digest_update(tfm, &tmp, 1);
118         crypto_digest_final(tfm, out);
119 }
120
121 void crypto_hmac(struct crypto_tfm *tfm, u8 *key, unsigned int *keylen,
122                  struct scatterlist *sg, unsigned int nsg, u8 *out)
123 {
124         crypto_hmac_init(tfm, key, keylen);
125         crypto_hmac_update(tfm, sg, nsg);
126         crypto_hmac_final(tfm, key, keylen, out);
127 }
128
129 EXPORT_SYMBOL_GPL(crypto_hmac_init);
130 EXPORT_SYMBOL_GPL(crypto_hmac_update);
131 EXPORT_SYMBOL_GPL(crypto_hmac_final);
132 EXPORT_SYMBOL_GPL(crypto_hmac);
133