crypto: hash - Fix handling of sg entry that crosses page boundary
[linux-2.6.git] / crypto / ahash.c
1 /*
2  * Asynchronous Cryptographic Hash operations.
3  *
4  * This is the asynchronous version of hash.c with notification of
5  * completion via a callback.
6  *
7  * Copyright (c) 2008 Loc Ho <lho@amcc.com>
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/hash.h>
17 #include <crypto/scatterwalk.h>
18 #include <linux/err.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/sched.h>
22 #include <linux/slab.h>
23 #include <linux/seq_file.h>
24
25 #include "internal.h"
26
27 static int hash_walk_next(struct crypto_hash_walk *walk)
28 {
29         unsigned int alignmask = walk->alignmask;
30         unsigned int offset = walk->offset;
31         unsigned int nbytes = min(walk->entrylen,
32                                   ((unsigned int)(PAGE_SIZE)) - offset);
33
34         walk->data = crypto_kmap(walk->pg, 0);
35         walk->data += offset;
36
37         if (offset & alignmask)
38                 nbytes = alignmask + 1 - (offset & alignmask);
39
40         walk->entrylen -= nbytes;
41         return nbytes;
42 }
43
44 static int hash_walk_new_entry(struct crypto_hash_walk *walk)
45 {
46         struct scatterlist *sg;
47
48         sg = walk->sg;
49         walk->pg = sg_page(sg);
50         walk->offset = sg->offset;
51         walk->entrylen = sg->length;
52
53         if (walk->entrylen > walk->total)
54                 walk->entrylen = walk->total;
55         walk->total -= walk->entrylen;
56
57         return hash_walk_next(walk);
58 }
59
60 int crypto_hash_walk_done(struct crypto_hash_walk *walk, int err)
61 {
62         unsigned int alignmask = walk->alignmask;
63         unsigned int nbytes = walk->entrylen;
64
65         walk->data -= walk->offset;
66
67         if (nbytes && walk->offset & alignmask && !err) {
68                 walk->offset += alignmask - 1;
69                 walk->offset = ALIGN(walk->offset, alignmask + 1);
70                 walk->data += walk->offset;
71
72                 nbytes = min(nbytes,
73                              ((unsigned int)(PAGE_SIZE)) - walk->offset);
74                 walk->entrylen -= nbytes;
75
76                 return nbytes;
77         }
78
79         crypto_kunmap(walk->data, 0);
80         crypto_yield(walk->flags);
81
82         if (err)
83                 return err;
84
85         if (nbytes) {
86                 walk->offset = 0;
87                 walk->pg++;
88                 return hash_walk_next(walk);
89         }
90
91         if (!walk->total)
92                 return 0;
93
94         walk->sg = scatterwalk_sg_next(walk->sg);
95
96         return hash_walk_new_entry(walk);
97 }
98 EXPORT_SYMBOL_GPL(crypto_hash_walk_done);
99
100 int crypto_hash_walk_first(struct ahash_request *req,
101                            struct crypto_hash_walk *walk)
102 {
103         walk->total = req->nbytes;
104
105         if (!walk->total)
106                 return 0;
107
108         walk->alignmask = crypto_ahash_alignmask(crypto_ahash_reqtfm(req));
109         walk->sg = req->src;
110         walk->flags = req->base.flags;
111
112         return hash_walk_new_entry(walk);
113 }
114 EXPORT_SYMBOL_GPL(crypto_hash_walk_first);
115
116 int crypto_hash_walk_first_compat(struct hash_desc *hdesc,
117                                   struct crypto_hash_walk *walk,
118                                   struct scatterlist *sg, unsigned int len)
119 {
120         walk->total = len;
121
122         if (!walk->total)
123                 return 0;
124
125         walk->alignmask = crypto_hash_alignmask(hdesc->tfm);
126         walk->sg = sg;
127         walk->flags = hdesc->flags;
128
129         return hash_walk_new_entry(walk);
130 }
131
132 static int ahash_setkey_unaligned(struct crypto_ahash *tfm, const u8 *key,
133                                 unsigned int keylen)
134 {
135         struct ahash_alg *ahash = crypto_ahash_alg(tfm);
136         unsigned long alignmask = crypto_ahash_alignmask(tfm);
137         int ret;
138         u8 *buffer, *alignbuffer;
139         unsigned long absize;
140
141         absize = keylen + alignmask;
142         buffer = kmalloc(absize, GFP_ATOMIC);
143         if (!buffer)
144                 return -ENOMEM;
145
146         alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
147         memcpy(alignbuffer, key, keylen);
148         ret = ahash->setkey(tfm, alignbuffer, keylen);
149         memset(alignbuffer, 0, keylen);
150         kfree(buffer);
151         return ret;
152 }
153
154 static int ahash_setkey(struct crypto_ahash *tfm, const u8 *key,
155                         unsigned int keylen)
156 {
157         struct ahash_alg *ahash = crypto_ahash_alg(tfm);
158         unsigned long alignmask = crypto_ahash_alignmask(tfm);
159
160         if ((unsigned long)key & alignmask)
161                 return ahash_setkey_unaligned(tfm, key, keylen);
162
163         return ahash->setkey(tfm, key, keylen);
164 }
165
166 static int ahash_nosetkey(struct crypto_ahash *tfm, const u8 *key,
167                           unsigned int keylen)
168 {
169         return -ENOSYS;
170 }
171
172 int crypto_ahash_import(struct ahash_request *req, const u8 *in)
173 {
174         struct crypto_ahash *tfm = crypto_ahash_reqtfm(req);
175         struct ahash_alg *alg = crypto_ahash_alg(tfm);
176
177         memcpy(ahash_request_ctx(req), in, crypto_ahash_reqsize(tfm));
178
179         if (alg->reinit)
180                 alg->reinit(req);
181
182         return 0;
183 }
184 EXPORT_SYMBOL_GPL(crypto_ahash_import);
185
186 static unsigned int crypto_ahash_ctxsize(struct crypto_alg *alg, u32 type,
187                                         u32 mask)
188 {
189         return alg->cra_ctxsize;
190 }
191
192 static int crypto_init_ahash_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
193 {
194         struct ahash_alg *alg = &tfm->__crt_alg->cra_ahash;
195         struct ahash_tfm *crt   = &tfm->crt_ahash;
196
197         if (alg->digestsize > PAGE_SIZE / 8)
198                 return -EINVAL;
199
200         crt->init = alg->init;
201         crt->update = alg->update;
202         crt->final  = alg->final;
203         crt->digest = alg->digest;
204         crt->setkey = alg->setkey ? ahash_setkey : ahash_nosetkey;
205         crt->digestsize = alg->digestsize;
206
207         return 0;
208 }
209
210 static void crypto_ahash_show(struct seq_file *m, struct crypto_alg *alg)
211         __attribute__ ((unused));
212 static void crypto_ahash_show(struct seq_file *m, struct crypto_alg *alg)
213 {
214         seq_printf(m, "type         : ahash\n");
215         seq_printf(m, "async        : %s\n", alg->cra_flags & CRYPTO_ALG_ASYNC ?
216                                              "yes" : "no");
217         seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
218         seq_printf(m, "digestsize   : %u\n", alg->cra_ahash.digestsize);
219 }
220
221 const struct crypto_type crypto_ahash_type = {
222         .ctxsize = crypto_ahash_ctxsize,
223         .init = crypto_init_ahash_ops,
224 #ifdef CONFIG_PROC_FS
225         .show = crypto_ahash_show,
226 #endif
227 };
228 EXPORT_SYMBOL_GPL(crypto_ahash_type);
229
230 MODULE_LICENSE("GPL");
231 MODULE_DESCRIPTION("Asynchronous cryptographic hash type");